Articles

93 documents.
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Vila M., V. Giussani, L. Viure, E. Alechaga, E. Moyano, S. Hernández-Llamas, E. Berdalet
, Ed. L.A.O. Proença and G.M. Hallegraeff. ISBN: 978-87-990827-6-6 (BibTeX: vila.etal.2018)
Kudela R.M., R. Raine, G. Pitcher, P. Gentien, E. Berdalet, H. Enevoldsen, E. Urban.
In: Global Ecology and Oceanography of Harmful Algal Blooms., Ecological Studies - Analysis and Synthesis Series.. Ed. Glibert, P.M., Berdalet, E., Burfort, M., Pitcher, G.. Springer International Publishing AG, Switzerland. Chap. 3. 27-49. DOI: 10.1007/978-3-319-70069-4 ISBN: 978-3-319-70069-4 (BibTeX: kudela.etal.2018)
Ed. P.M. Glibert, E. Berdalet, M. Burfort, G. Pitcher, M. Zhou (Eds.). Springer International Publishing AG. 232, In: Ecological Studies - Analysis and Synthesis Series.. 461. ISBN: 978-3-319-70068-7 (BibTeX: .2018)
Berdalet E., R. Kudela, N. S. Banas, E. Bresnan, M. Burford, K. Davidson, C. J. Gobler, B. Karlson, P.-T. Lim, L. Mackenzie, M. Montresor, V. L. Trainer, G. Usup, K. Yin, H. Enevoldsen, E. Urban.
In: Global Ecology and Oceanography of Harmful Algal Blooms., Ecological Studies - Analysis and Synthesis Series.. Ed. Glibert, P.M., Berdalet, E., Burfort, M., Pitcher, G., M. Zhou. Springer International Publishing AG, Switzerland. Chap. 22. 425-447. DOI: 10.1007/978-3-319-70069-4 ISBN: 978-3-319-70069-4 (BibTeX: berdalet.etal.2018)
Glibert P.M., E. Berdalet, M. Burfort, G. Pitcher, M. Zhou
In: Global Ecology and Oceanography of Harmful Algal Blooms., Ecological Studies - Analysis and Synthesis Series.. Ed. Glibert, P.M., Berdalet, E., Burfort, M., Pitcher, G., M. Zhou. Springer International Publishing AG, Switzerland. Chap. 2. 9-25. DOI: 10.1007/978-3-319-70069-4 ISBN: 978-3-319-70069-4 (BibTeX: glibert.etal.2018a)
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Vassalli M., A. Penna, F. Sbrana, S. Casabianca, N. Gjeci, S. Capellacci, V. Asnaghi, E. Ottaviani, V. Giussani, L. Pugliese, C. Jauzein, R. Lemée, L. Açaf, M.A. Hachani, S. Turki, M. Abboud-Abi Saab, A. Fricke, L. Mangialajo, R. Bertolotto, C. Totti, S. Accoroni, E. Berdalet, M. Vila, M. Chiantore
Ecological Indicators, 85, 1092-1100. DOI: 10.1016/j.ecolind.2017.07.063 (BibTeX: vassalli.etal.2018)
Raine R., E. Berdalet, H. Yamazaki, I. Jenkinson, B. Reguera
In: Global Ecology and Oceanography of Harmful Algal Blooms., Ecological Studies - Analysis and Synthesis Series.. Ed. Glibert, P.M., Berdalet, E., Burfort, M., Pitcher, G.. Springer International Publishing AG, Switzerland. Chap. 9. 165-186. DOI: 10.1007/978-3-319-70069-4 ISBN: 978-3-319-70069-4 (BibTeX: raine.etal.2018)
Berdalet E., P. Tester
In: Global Ecology and Oceanography of Harmful Algal Blooms., Ecological Studies - Analysis and Synthesis Series.. Ed. Glibert, P.M., Berdalet, E., Burfort, M., Pitcher, G., M. Zhou. Springer International Publishing AG, Switzerland. Chap. 13. 261-286. DOI: 10.1007/978-3-319-70069-4 ISBN: 978-3-319-70069-4 (BibTeX: berdalet.tester.2018)
Glibert P.M., E. Berdalet, M. Burfort, G. Pitcher, M. Zhou
In: Global Ecology and Oceanography of Harmful Algal Blooms., Ecological Studies - Analysis and Synthesis Series.. Ed. Glibert, P.M., Berdalet, E., Burfort, M., Pitcher, G., M. Zhou. Springer International Publishing AG, Switzerland. Chap. 1. 3-7. DOI: 10.1007/978-3-319-70069-4 ISBN: 978-3-319-70069-4 (BibTeX: glibert.etal.2018)
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Friedman M.A., M. Fernandez, L.C. Backer, R.W. Dickey, J. Bernstein, K. Schrank, S. Kibler, W. Stephan, M.O. Gribble, P. Bienfang, R.E. Bowen, S. Degrasse, H.A. Flores Quintana, C.R. Loeffler , R. Weisman, D. Blythe, E. Berdalet, R. Ayyar, D. Clarkson-Townsend, K. Swajian, R. Benner, T. Brewer, L.E. Fleming
Marine Drugs, 15, 72, 1-41. DOI: 10.3390/md15030072 (BibTeX: friedman.etal.2017)
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Kudela R.M., E. Berdalet, H. Enevoldsen, G. Pitcher, R. Raine, E. Urban
Oceanography, 30, 1, 12-21. DOI: 10.5670/oceanog.2017.106 (BibTeX: kudela.etal.2017a)
Resum: Veure
In 2001, the first international research program focusing exclusively on harmful marine algae, GEOHAB (Global Ecology and Oceanography of Harmful Algal Blooms), was established by the HAB research community, under the sponsorship of the Intergovernmental Oceanographic Commission of UNESCO and the Scientific Committee on Oceanic Research. Its mission was to foster international cooperation to advance understanding of HAB dynamics and to improve our ability to predict them. The main efforts were focused on (1) the physiological, behavioral, and genetic characteristics of harmful microalgal species, and (2) the interactions between physical and other environmental conditions that promote the success of one group of species over another. GEOHAB was designed to study HABs with a view to integrating global data from comparable ecosystems. With an international, multidisciplinary, and comparative approach, GEOHAB advanced our understanding of the mechanisms underlying population dynamics of HABs within an ecological and oceanographic context and from an ecosystem perspective at the regional scale. GEOHAB encouraged combined experimental, observational, and modeling tools, using both existing and innovative technologies in a multidisciplinary approach, consistent with the multiple scales and oceanographic complexity of HAB phenomena. GEOHAB established the basis for continued international efforts now and into the future in order to better understand and predict the global complex phenomena of harmful algal blooms.
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Berdalet E., R. Kudela, E. Urban, H. Enevoldsen, N.S. Banas, E. Bresnan, M. Burford, K. Davidson, C.J. Gobler, B. Karlson, P. Teen Lim, L. Mackenzie, M. Montresor, V.L. Trainer, G. Usup, K. Yin
Oceanography, 30, 1, 70-81. DOI: 10.5670/oceanog.2017.111 (BibTeX: berdalet.etal.2017a)
Resum: Veure
From 1998 to 2013, the international community of scientists researching harmful algal blooms (HABs) in marine systems worked through the Intergovernmental Oceanographic Commission (IOC) of UNESCO and the Scientific Committee on Oceanic Research (SCOR) to better understand the ecological and oceanographic controls on these natural events that cause harm to humans and ecosystems. During this period, IOC and SCOR cosponsored the Global Ecology and Oceanography of Harmful Algal Blooms (GEOHAB) program to facilitate progress in HAB research, observations, and modeling. In 2016, building on the foundation provided by GEOHAB, IOC and SCOR launched a new HAB project design to extend research into freshwater systems and address several topics related to the effects of HABs on human society now and in a rapidly changing world.
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Berdalet E., P.A. Tester, M. Chinain, S. Fraga, R. Lemée, W. Litaker, A. Penna, G. Usup, M. Vila, A. Zingone
Oceanography, 30, 1, 36-45. DOI: 10.5670/oceanog.2017.108 (BibTeX: berdalet.etal.2017e)
Resum: Veure
Shallow, well-illuminated coastal waters from tropical to temperate latitudes are attractive environments for humans. Beaches and coral reefs have provided lodging and food to coastal communities for centuries. Unfortunately, tropical regions traditionally have been threatened by outbreaks of the toxic benthic dinoflagellate Gambierdiscus, which is associated with ciguatera fish poisoning. The ciguatoxins produced by Gambierdiscus bioaccumulate in reef fishes and are responsible for the most common algal toxin-related illnesses, globally affecting the greatest number of victims and often with significant long-term health effects. Recently, Gambierdiscus has been documented in subtropical and temperate latitudes. Blooms of another benthic and toxic dinoflagellate, Ostreopsis, have become more frequent and intense, especially in temperate waters. Ostreopsis produces palytoxins and analogues, and some outbreaks have been associated with massive benthic faunal damage and respiratory irritations in humans exposed to aerosols. The increased frequency of harmful events and the biogeographic extension of benthic microalgae incentivized the launch of the Global Ecology and Oceanography of Harmful Algal Blooms (GEOHAB) Core Research Project on “Benthic Harmful Algal Blooms” in 2010. This article summarizes the main scientific advances and gaps in related knowledge as well as advances the project has made toward managing and mitigating the impacts of benthic HABs on human illnesses and marine resource losses.
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Berdalet E., M. Montresor, B. Reguera, S. Roy, H. Yamazaki, A. Cembella, R. Raine
Oceanography, 30, 1, 46-57. DOI: 10.5670/oceanog.2017.109 (BibTeX: berdalet.etal.2017c)
Resum: Veure
Harmful algal blooms (HABs) are natural phenomena that result from the interplay of biological, chemical, physical, and sedimentary processes occurring at different temporal and spatial scales. This paper provides an integrated description of HAB dynamics occurring at the mesoscale (10–100 km, sensu Haury et al., 1978) in confined and semi-confined coastal environments and under stratified water column conditions in a diversity of habitats where HAB events occur. It also focuses on relevant aspects occurring at fine-scale and even smaller cellular scales that are critical to species interactions with their environments. Examples include the key role of life-history stages in the recurrence of HABs in certain embayments; the physical-biological interactions driving the formation, maintenance, and decline of thin layers of plankton, including harmful microalgae; the fascinating, but poorly understood, domain of small-scale chemical interactions between HAB species and components of the food web; the potential link between human activities and climate change; and the trends in HAB occurrence. Development of new observing and sampling technologies and of new modeling approaches has resulted in greater understanding of these phenomena. Two Core Research Projects initiated under the GEOHAB Implementation Strategy, “HABs in Fjords and Coastal Embayments” and “HABs in Stratified Systems,” are discussed and priorities for future research toward improving the management and mitigation of HAB impacts are outlined
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Berdalet E., D. Blasco, D. Vaqué
Scientia Marina, 80, S1, 11-14. DOI: 10.3989/scimar.04529.06A (BibTeX: berdalet.etal.2016c)
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Giussani V., E. Costa, D. Pecorino, E. Berdalet, G. De Giampaulis, M. Gentile, V. Fuentes, M. Vila, A. Penna, M. Chiantore, F. Garaventa, S. Lavorano, M. Faimali
Harmful Algae, 57, Part A, 49-58. DOI: 10.1016/j.hal.2016.05.005 (BibTeX: giussani.etal.2016a)
Resum: Veure
The frequency and geographic extension of microalgae and gelatinous zooplankton blooms seem to have been increasing worldwide over recent decades. In particular, the harmful dinoflagellate Ostreopsis cf. ovata and the Schyphozoan jellyfish Aurelia sp. are two of the most frequent and long lasting species forming blooms in the Mediterranean Sea. A kind of interaction among any of their life cycle stages (i.e. planula-polyp-ephyrae vs Ostreopsis cells) can likely occur, although in this area there are no data available on the co-occurrence of these species. The aim of this study was to investigate, for the first time, the potential noxious effect of O. cf. ovata on different life stages of Aurelia sp. (polyps and ephyrae), testing several concentrations of whole algal culture. Rsults of toxicity bioassay highlighted that ephyrae, but not polyps, are affected by this harmful dinoflagellate and comparisons among other model organisms show that Aurelia sp. ephyrae are the most sensitive model organism tested so far (EC50–24 h = 10.5 cells/mL). These findings suggest an interesting scenario on the interaction of these two bloom forming species in the natural marine environment.
Paraules clau: Ostreopsis, Aurelia sp., HABs, Jellyfish bloom, Polyps, Toxicology
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Vila M., R. Abós-Herràndiz, J. Isern-Fontanet, J. Àlvarez, E. Berdalet
Scientia Marina, 80, S1, 107-115. (BibTeX: vila.etal.2016)
Resum: Veure
Blooms of the benthic dinoflagellate Ostreopsis have been related to sporadic acute respiratory symptoms and general malaise in people exposed to marine aerosols on some Mediterranean beaches. However, the direct link between recurrent Ostreopsis blooms and health problems has not been clearly established. In order to establish and elucidate the connection, we conducted a joint ecology and epidemiology study in an Ostreopsis hot spot. Throughout the bloom, which extended from the end of June until the end of October 2013, 81% of the human cohort that we studied experienced at least one Ostreopsis-related symptom. Paradoxically, the time when the effects were greatest was during a short time window in early August. This corresponded to the transition from the exponential growth to the stationary phase of the bloom. Negligible symptoms were reported from August to mid-October, during the stationary period of the proliferation, when O. cf. ovata maintained high concentrations of epiphytic cells. No clear patterns in the landward wind component were noted during the time when health effects were greatest. Our main hypothesis is that the irritants present in the aerosol are produced during a particular physiological phase of the Ostreopsis cells during the bloom.
Paraules clau: Ostreopsis, epidemiology, Mediterranean, HAB, dinoflagellates, respiratory irritation, epidemiología, Mediterráneo, proliferaciones algales nocivas, dinoflagelados, irritaciones respiratorias
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Berdalet E., L.E. Fleming, R. Gowen, K. Davidson, P. Hess, L.C. Backer, S.K. Moore, P. Hoagland, H. Enevoldsen
Journal of the Marine Biological Association of the United Kingdom, 96, 1, 61-91. DOI: 10.1017/S0025315415001733 (BibTeX: berdalet.etal.2016a)
Resum: Veure
Microalgal blooms are a natural part of the seasonal cycle of photosynthetic organisms in marine ecosystems. They are key components of the structure and dynamics of the oceans and thus sustain the benefits that humans obtain from these aquatic environments. However, some microalgal blooms can cause harm to humans and other organisms. These harmful algal blooms (HABs) have direct impacts on human health and negative influences on human wellbeing, mainly through their consequences to coastal ecosystem services (fisheries, tourism and recreation) and other marine organisms and environments. HABs are natural phenomena, but these events can be favoured by anthropogenic pressures in coastal areas. Global warming and associated changes in the oceans could affect HAB occurrences and toxicity as well, although forecasting the possible trends is still speculative and requires intensive multidisciplinary research. At the beginning of the 21st century, with expanding human populations, particularly in coastal and developing countries, mitigating HABs impacts on human health and wellbeing is becoming a more pressing public health need. The available tools to address this global challenge include maintaining intensive, multidisciplinary and collaborative scientific research, and strengthening the coordination with stakeholders, policymakers and the general public. Here we provide an overview of different aspects of the HABs phenomena, an important element of the intrinsic links between oceans and human health and wellbeing.
Paraules clau: Harmful algal blooms, human health and wellbeing, marine biotoxins, ecosystem services
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Solé J., E. Berdalet, L. Arin, Ll. Cros, M. Delgado, A. Kuwata, C. Llebot, C. Marrasé
Scientia Marina, 80, S1, 33-38. DOI: 10.3989/scimar.04520.06D (BibTeX: sole.etal.2016e)
Resum: Veure
Plankton ecology has been the object of intense research and progress in the last few decades. This has been partly due to technological advances that have facilitated the multidisciplinary and high-resolution sampling of ecosystems and improved experimentation and analytical methodologies, and to sophisticated modelling. In addition, exceptional researchers have had the vision to integrate all these innovative tools to form a solid theoretical background in ecology. Here we provide an overview of the outstanding research work conducted by Professor Marta Estrada and her pioneering contribution to different areas of research in the last four decades. Her research in biological oceanography has mainly focussed on phytoplankton ecology, taxonomy and physiology, the functional structure of plankton communities, and physical and biological interactions in marine ecosystems. She has combined a variety of field and laboratory approaches and methodologies, from microscopy to satellite observations, including in-depth statistical data analysis and modelling. She has been a reference for scientists all over the world. Here, her contributions to plankton ecology are summarized by some of her students and closest collaborators, who had the privilege to share their science and everyday experiences with her.
Paraules clau: Phytoplankton ecology, taxonomy, functional structure of plankton communities, physical-biological interactions, ecología del fitoplancton, taxonomía, estructura funcional de las comunidades plantónicas, interacciones física-biología
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Jenkinson I.R., E. Berdalet, W.C. Chin, S. Herminghaus, S. Leterme, J.G. Mitchell, M. Orchard, R. Qiu, L. Seuront, P. Wang, T. Wyatt, L. Zhuo.
Marine and Freshwater Harmful Algae. Proceedings of the 16th International Conference on Harmful Algae, Wellington, New Zealand 27th-31st October 2014., . Ed. A. Lincoln MacKenzie. 171-174. ISBN: 978-87-990827-5-9 (BibTeX: jenkinson.etal.2015)
Resum: Veure
Have you ever wondered how algae stay so clean? Most flowering-plant leaves also stay clean. Under air, films of water and "dirt" are repelled. Repulsion forces the water into droplets that easily roll off because these leaves are covered in hydrophobic nanometre (nm) to micrometre (µm) sized grooves and pillars, producing superhydrophobicity (SH) at the surface. Similarly, most algal cells bear a glycocalyx of organic fibrils that give surface structure, and are often hydrophobic. Glycocalyxes serve many functions, but whether they produce SH is poorly known. SH coatings are being developed to prevent fouling of ships and aquaculture structures without using toxins, so this technology could help understand how algae defeat fouling. Glycocalyxes are composed of exopolymeric secretions (EPS), and algae sometimes make the water more viscous using this tightly and more loosely bound EPS. EPS is also sometimes sticky. SH cuticles on copepods may change ambient fluid microdynamics by allowing slip at their surfaces, and facilitate filter feeding. By managing ambient viscosity and surface properties including slipping and sticking, algae may have the tools to engineer ambient fluidics and stay clean and unfouled.
Paraules clau: Rheology, micro/nanoFluidics and bioFouling in the Oceans
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Romero-Kutzner V., T.T. Packard, E. Berdalet, S.O. Roy, J.P. Gagné, M. Gómez
Marine Ecology Progress Series, 519, 47-59. DOI: 10.3354/meps11062 (BibTeX: romerokutzner.etal.2015)
Resum: Veure
Respiratory metabolism was compared between 2 different physiological states of acetate- and pyruvate-grown cultures of Pseudomonas nautica and Vibrio natriegens. Here, we analyze 35 h and 520 h experiments in which time-courses of protein, pyruvate, acetate, respiratory CO2 production (RCO2), respiratory O2 consumption (RO2), isocitrate dehydrogenase (IDH) activity, and potential respiration (Φ) were measured. Respiratory quotients (RQs) were calculated as the ratio of the respiration rates (RCO2/RO2). Such RQs are widely used in ocean ecosystem models, in calculations of carbon flux, and in evaluations of the ocean’s metabolic balance. In all the cultures, the RQ tended to increase. In the case of P. nautica on acetate, the RQ rose nearly an order of magnitude from values below 1 during carbon-substrate sufficiency to values close to 10 during carbon-substrate deficiency. In all the cultures, the respiration rates during the growth period paralleled the biomass increase, but after the substrates were exhausted, the respiration rates fell. In contrast, through this same transition period, the IDH activity and the Φ remained relatively high for the first 10 h of carbon-substrate deprivation, and then, these enzyme activities fell slowly, along with the biomass, as the carbon-substrate deprivation continued. The nutritional state of the bacteria affected the RQ, rendering the RQ variable for physiological and ecological purposes. These results argue that ecosystem models, oceanographic calculations of carbon flux, and evaluations of the ocean’s metabolic balance that are influenced by bacterial metabolism need to be reconsidered in light of RQ variability.
Paraules clau: O2 consumption, CO2 production, Isocitrate dehydrogenase, IDH, Electron transport system, ETS, Potential respiration, Growth
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Raine R., E. Berdalet, M. McManus, H. Yamazaki (Guest Editors)
101, 1-254. (BibTeX: raine.etal.2014a)
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Berdalet E., S. Bernard, M.A. Burford, H. Enevoldsen, R.M. Kudela, R. Magnien, S. Roy, P.A. Tester, E. Urban, G. Usup
Resum: Veure
This report is based on contributions and discussions by the organizers and participants of the workshop, and the GEOHAB Scientific Steering Committee.
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Berdalet E., M.L. Artigas, C. Llebot, O.N. Ross, A.B. Hoyer, N.Z. Neszi, J. Piera, F. Rueda, M. Estrada
Harmful Algae 2012, Proceedings of the 15th International Conference on Harmful Algae, . Ed. H.G. Kim, B. Reguera, G.M. Hallegraeff, C.K. Lee, M.S. Han, J.K. Choi. International Society for the Study of Harmful Algae. 55-58. ISBN: 978-87-990827-4-2 (BibTeX: berdalet.etal.2014c)
Resum: Veure
Understanding the spatio-temporal variability of phytoplankton in aquaculture areas is necessary for the appropriate management of natural resources and the prevention of toxic outbreaks. With this objective, we combined synoptic cruises, time series of physical parameters, and modeling, to study the ecosystem of Alfacs Bay, an important shellfish and fish production area commonly affected by toxic outbreaks.Synoptic cruises performed during relevant harmful species proliferations, such as a Karlodinium spp. outbreak in 2007, showed the existence of a preferential phytoplankton accumulation area in the inner NE side of the Bay. We explored the role of nutrient supply (which takes place mainly through the irrigation channels discharging into the northern coast) and the hydrodynamic regime in explaining the observed phytoplankton distribution patterns. Based on a 3D hydrodynamic model combined with a particle-tracking module, we suggest that the phytoplankton confinement in that area could be fostered by the estuarine circulation dynamics taking place in the bay.
Paraules clau: Alfacs bay, NW Mediterranean, phytoplankton dynamics, estuarine circulation
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Raine R., E. Berdalet, M.A.McManus, H. Yamazaki.
101, 1-3. ISSN: 0967-0645 (BibTeX: raine.etal.2014)
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Berdalet E., M.A. McManus, O.N. Ross, H. Burchard, F.P. Chavez, J.S. Jaffe, I.R. Jenkinson, R. Kudela, I. Lips, U. Lips, A. Lucas, D. Rivas, M.C. Ruiz-de la Torre, J. Ryan, J.M. Sullivan, H. Yamazaki
Deep-Sea Research Part II: Topical Studies in Oceanography, 101, 4-20. DOI: 10.1016/j.dsr2.2013.09.042 (BibTeX: berdalet.etal.2014a)
Resum: Veure
The Global Ecology and Oceanography of Harmful Algal Blooms (GEOHAB) program of the Scientific Committee on Oceanic Research (SCOR) and the Intergovernmental Oceanographic Commission (IOC) of UNESCO, was created in 1999 to foster research on the ecological and oceanographic mechanisms underlying the population dynamics of harmful algal blooms (HABs). The ultimate goal of this research is to develop observational systems and models that will eventually enable the prediction of HABs and thereby minimize their impact on marine ecosystems, human health and economic activities. In August of 2012, a workshop was held under the umbrella of the GEOHAB program at the Monterey Bay Aquarium Research Institute (MBARI). The over arching goal of this workshop was to review the current understanding of the processes governing the structure and dynamics of HABs in stratified systems, and to identify how best to couple physical/chemical and biological measurements at appropriate spatial and temporal scales to quantify the dynamics of HABs in these systems, paying particular attention to thin layers. This contribution provides a review of recent progress in the field of HAB research in stratified systems including thin layers, and identifies the gaps in knowledge that our scientific community should strive to understand in the next decade.
Paraules clau: Harmful algal blooms; Thin layers; Phytoplankton detection methods; Modeling; Motility; Observational systems
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Artigas M.L., C. Llebot, O.N. Ross, N.Z. Neszi, V. Rodellas, J. Garcia-Orellana, P. Masqué, J. Piera, M. Estrada, E. Berdalet
Deep-Sea Research Part II: Topical Studies in Oceanography, 101, 180-192. DOI: 10.1016/j.dsr2.2014.01.006 (BibTeX: artigas.etal.2014)
Resum: Veure
Understanding the spatio-temporal variability of phytoplankton in aquaculture zones is necessary for the prevention and/or prediction of harmful algal bloom events. Synoptic cruises, time series analyses of physical and biological parameters, and 3D modeling were combined to investigate the variability of phytoplankton biomass in Alfacs Bay at basin scale. This microtidal estuary located in the NW Mediterranean is an important area of shellfish and finfish exploitation, which is regularly affected by toxic outbreaks. Observations showed the existence of a preferential phytoplankton accumulation area on the NE interior of the bay. This pattern can be observed throughout the year, and we show that it is directly linked to the physical forcing in the bay, in particular, the interplay between freshwater input and wind-induced turbulence. Both drivers affect the strength of the estuarine circulation, explaining nearly 75% of the variability in phytoplankton biomass. More cells are retained when stratification is weakened and the estuarine circulation reduced, while flushing rates are higher during times of increased stratification and stronger estuarine flow. This has been confirmed by using a 3D hydrodynamic model with Eulerian tracers. Nutrients, while important to support phytoplankton populations, have been found to play only a secondary role in explaining this variability at basin scale.
Paraules clau: Microtidal estuary; Phytoplankton variability; Alfacs Bay; Physical–biological interactions; Estuarine circulation; Meteorological forcing
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Simon F.X., E. Rudé, E. Berdalet, J. Llorens, S. Baig
Chemosphere, 91, 9, 1297–1303. DOI: 10.1016/j.chemosphere.2013.02.056 (BibTeX: simon.etal.2013)
Resum: Veure
Biofilters degrade a small fraction of the natural organic matter (NOM) contained in seawater which is the leading cause of biofouling in downstream processes. This work studies the effects of chemical additions on NOM biodegradation by biofilters. In this work, biofiltration of seawater with an empty bed contact time (EBCT) of 6 min and a hydraulic loading rate of 10 m h−1 reduces the biological oxygen demand (BOD7) by 8%, the dissolved organic carbon (DOC) by 6% and the UV absorbance at 254 nm (A254) by 7%. Different amounts of ammonium chloride are added to the seawater (up to twice the total dissolved nitrogen in untreated seawater) to study its possible effect on the removal of NOM by a pilot-scale biofilter. Seawater is amended with different amounts of easily biodegradable dissolved organic carbon (BDOC) supplied as sodium acetate (up to twice the DOC) for the same purpose. The results of this work reveal that the ammonium chloride additions do not significantly affect NOM removal and the sodium acetate is completely consumed by the biofiltration process. For both types of chemical additions, the BOD7, DOC and A254 in the outlet stream of the biofilter are similar to the values for the untreated control. These results indicate that this biofilter easily removes the BDOC from the seawater when the EBCT is not above 6 min. Furthermore, nitrogen does not limit the NOM biodegradation in seawater under these experimental conditions.
Paraules clau: Seawater; Biofiltration; Inorganic nitrogen; Biodegradable organic carbon
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McManus M.A., E. Berdalet, J. Ryan, H. Yamazaki, J.S. Jaffe, O.N. Ross, H. Burchard, F.P. Chavez (Eds.)
IOC and SCOR. In: Report. (BibTeX: mcmanus.etal.2013)
Resum: Veure
This report is based on contributions and discussions by the organizers and participants of the workshop
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GEOHAB, Ed. E. Berdalet, P. Tester, A. Zingone. 9, 1-64. Paris and Newark. (BibTeX: .2012b)
Resum: Veure
This report is based on contributions and discussions by participants of the GEOHAB open science meeting on habs in benthic systems and members of the geohab scientific steering committee.
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Zingone A., E. Berdalet, P. Bienfang, H. Enevoldsen, J. Evans, R. Kudela, P. Tester
Cryptogamie-algologie, 33, 2, 225-230. (BibTeX: zingone.etal.2012)
Resum: Veure
Harmful events caused by benthic microalgae have recently garnered a high level of attention in temperate areas, upon reports of Ostreopsis species causing fauna damage, food intoxication and respiratory illness. A resurgence of interest has also occurred in ciguatera fish poisoning (CFP), a syndrome associated with the consumption of reef fish contaminated by ciguatoxins produced by the dinoflagellate genus Gambierdiscus in tropical and subtropical areas. To foster research on events caused by benthic microalgae, the SCOR-IOC Global Ecology and Oceanography on Harmful Algal Blooms (GEOHAB) program started a Core Research Project on Benthic Harmful Algal Blooms (BHABs). During an Open Science Meeting (OSM) in 2010, scientists studying benthic and planktonic microalgae identified the main gaps of knowledge and the research, technology and infrastructure needs in the field of the ecology and oceanography of BHABs. The issues addressed during the OSM covered the state of taxonomy, sampling methods, biogeography, genetic diversity, ecology and ecophysiology of BHABs, along with the identification of research priorities and approaches to be taken in order to improve understanding and prediction of BHABs.
Paraules clau: Ecology / Gambierdiscus / GEOHAB / HABs / Harmful algae / Ostreopsis
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Aguiar-González B., T.T. Packard, E. Berdalet, S. Roy, M. Gómez
Journal of Experimental Marine Biology and Ecology, 412, 31, 1-12. DOI: 10.1016/j.jembe.2011.09.018 (BibTeX: aguiargonzalez.etal.2012)
Resum: Veure
Respiratory oxygen consumption is the result of a cell\'s biochemistry. It is caused by enzymatic activity of the respiratory electron transfer system (ETS). However, in spite of this understanding, respiration models continue to be based on allometric equations relating respiration to body size, body surface, or biomass. The Metabolic Theory of Ecology (MTE) is a current example. It is based on Kleiber\'s law relating respiration (R) and biomass (M) in the form, View the MathML source, where C is a constant, Ea is the Arrhenius activation energy, k is the Boltzmann constant for an atom or molecule, and T is the temperature in Kelvin. This law holds because biomass packages the ETS. In contrast, we bypass biomass and model respiration directly from its causal relationship with the ETS activity, R = f (ETS). We use a biochemical Enzyme Kinetic Model (EKM) of respiratory oxygen consumption based on the substrate control of the ETS. It postulates that the upper limit of R is set by the maximum velocity, Vmax, of complex I of the ETS and the temperature, and that the substrate availability, S, modulates R between zero and this upper limit. Kinetics of this thermal-substrate regulation is described by the Arrhenius and Michaelis–Menten equations. The EKM equation takes the form View the MathML source where Rg is the molar gas constant and K is the Michaelis–Menten constant. Here, we apply the EKM and the MTE to predict a respiration time-profile throughout the exponential, steady state, and nutrient-limited phases of the marine bacteria Pseudomonas nautica and Vibrio natriegens in acetate-based cultures. Both models were tested by comparing their output with the measured RO2 time-profile. The MTE predicted respiration accurately only in the exponential growth phase, but not during the nutrient limitation part of the stationary phase. In contrast, the EKM worked well throughout both physiological phases as long as the modeled substrates fall with the declining carbon source. Results support the theoretical bases of the EKM. We conclude that the EKM holds promise for predicting respiration at the different physiological states and time-scales important to microbiological studies.
Paraules clau: ETS; Modeling respiration; MTE; Oxygen consumption
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, Ed. D.J. McGillicuddy Jr., P.M. Glibert, E. Berdalet, C. Edwards, P. Franks, O. Ross (eds). 85. ISSN: 1538 182X (BibTeX: .2011b)
Resum: Veure
Based on contributions of the participants of the GEOHAB Modelling Workshop
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Ross O.N., R.J. Geider, E. Berdalet, M.L. Artigas, J. Piera
Marine Ecology Progress Series, 435, 13-31. DOI: 10.3354/meps09193 (BibTeX: ross.etal.2011b)
Resum: Veure
Reliable estimates of in situ phytoplankton growth rates are central to understanding the dynamics of aquatic ecosystems. A common approach for estimating in situ growth rates is to incubate natural phytoplankton assemblages in clear bottles at fixed depths or irradiance levels and measure the change in chlorophyll a (Chl) over the incubation period (typically 24 h). Using a modelling approach, we investigate the accuracy of these Chl-based methods focussing on 2 aspects: (1) in a freely mixing surface layer, the cells are typically not in balanced growth, and with photoacclimation, changes in Chl may yield different growth rates than changes in carbon; and (2) the in vitro methods neglect any vertical movement due to turbulence and its effect on the cells’ light history. The growth rates thus strongly depend on the incubation depth and are not necessarily representative of the depth-integrated in situ growth rate in the freely mixing surface layer. We employ an individual based turbulence and photosynthesis model, which also accounts for photoacclimation and photoinhibition, to show that the in vitro Chl-based growth rate can differ both from its carbon-based in vitro equivalent and from the in situ value by up to 100%, depending on turbulence intensity, optical depth of the mixing layer, and incubation depth within the layer. We make recommendations for choosing the best depth for single-depth incubations. Furthermore we demonstrate that, if incubation bottles are being oscillated up and down through the water column, these systematic errors can be significantly reduced. In the present study, we focus on Chl-based methods only, while productivity measurements using carbon-based techniques (e.g. 14C) are discussed in Ross et al. (2011; Mar Ecol Prog Ser 435:33–45).
Paraules clau: Chlorophyll · Photoacclimation · Photoinhibition · Lagrangian modelling · Individual based modelling · Turbulence · Surface mixing layer · Yo-yo technique
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Berdalet E., G. Llaveria, R. Simó
Harmful Algae, 11, 88-95. DOI: 10.1016/j.hal.2011.08.003 (BibTeX: berdalet.etal.2011)
Resum: Veure
Some marine dinoflagellates produce important amounts of dimethylsulfoniopropionate (DMSP), a common compatible solute, and its cleavage product dimethylsulfide (DMS), a climatically active trace gas. In the field, dinoflagellate proliferations appear to be favored by calm weather and water column stability; indeed, small-scale turbulence is a physical factor that directly affects ecophysiological aspects of this phytoplankton group, including toxin production. Here we report the effect of experimentally generated turbulence on DMSP production by a paralytic shellfish poisoning (PSP) toxin producing strain of Alexandrium minutum, a widespread bloomforming dinoflagellate species. With respect to still conditions, the populations exposed to turbulence grew at a slower growth rate and yielded low cell numbers turbulence. Concurrently, the cellular DMSP concentration increased by ca. 20% (from 0.22 ± 0.01 to 0.27 ± 0.03 fmol μm−3 on a cell volume basis) in the shaken cultures. DMSP was preferentially synthesized during the light period in both treatments. During the night, a slowdown of the division process caused DMSP accumulation in the cells exposed to shaking. The study suggests the existence of a tight link between the dynamics of DMSP concentration and other cell processes entrained by circadian rhythms in dinoflagellates. The observed effects of small-scale turbulence on the DMSP dynamics supports the suggested role of this compound as an overflow mechanism in metabolically unbalanced cells. Furthermore, considering all the effects on the physiology of A. minutum exposed to the same experimental setup, we propose a possible link between the DMSP and the PSP metabolisms.
Paraules clau: DMSP, dimethylsulfoniopropionate; DMS, dimethylsulfide; PSP, paralytic shellfish poisoning
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Yebra L., E. Berdalet, R. Almeda, V. Pérez, A. Calbet, E. Saiz
Journal of Experimental Marine Biology and Ecology, 406, 1-2, 87-94. DOI: 10.1016/j.jembe.2011.06.019 (BibTeX: yebra.etal.2011)
Resum: Veure
Despite the abundance of the marine copepod genus Oithona, little is known about its ecology and metabolism, especially regarding its early developmental stages. In this work, we combined two biochemical indices, already used in calanoid copepods, to estimate growth and fitness of Oithona davisae nauplii and copepodites: i) the specific aminoacyl-tRNA synthetases (spAARS) activity (proxy of protein synthesis rate) and ii) the RNA/DNA ratio (indicative of overall metabolic activity). We show here that the two analyses can be performed on the same organisms (samples), thus providing comparable and complementary information about the nauplii physiology. Our experiments provide a first insight into the variability of these parameters on O. davisae early developmental stages, showing that RNA/DNA ratio was more sensitive to starvation than the spAARS activity. A common relationship for nauplii and copepodites was observed between spAARS activity and somatic growth rates; however, RNA/DNA ratio relationships with both somatic growth rates and spAARS activity differed between the naupliar and copepodite stages. The study presented here contributes to the advancement of the study of small copepod nauplii physiology.
Paraules clau: AARS; Growth; Metabolism; Nauplii; Oithona davisae; RNA/DNA
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Karp-Boss L., E. Boss, H. Weller, J. Loftin, J. Albright. Traducción de: J. Ballabrera, E. Berdalet, M. Claret, E. García-Ladona, A. García-Olivares, A. López de Aretxabaleta, J. Salat, A. Turiel, Á. Viúdez
In: Oceanography, Vol. 22. Ed. Ellen Kappel and Vicky Cullen. The Oceanography Society. Chap. 3. 54 pp. (BibTeX: karpboss.etal.2010d)
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Berdalet E., O.N. Ross, J. Solé, M.L. Artigas, G. Llaveria, C. Llebot, R. Quesada, J. Piera, M. Estrada
, Ed. International Council for the Exploration of the Sea. N:02. ISBN: 978-87-7482-085-7 (BibTeX: berdalet.etal.2010a)
Resum: Veure
The mechanisms underlying the population dynamics of species causing Harmful Algal Blooms (HABs) are complex because they result from the interplay of a spectrum of physico-chemical and biological factors, to which the organisms respond with a variety of strategies. Still, it is not clear whether the responses of harmful species are different from other phytoplankters. In order to resolve some of these questions, we started a multidisciplinary study in 2007 in Alfacs Bay (Ebre Delta), an active aquaculture site in the NW Mediterranean that is exposed to recurrent HAB events. Through a series of meteorological and hydrographical observations combined with modelling exercises, we try to understand how the circulation in the Bay affects the retention, dispersion, and thus the net development of (harmful) phytoplankton populations. The small-scale characterization of the physical water column properties is performed using a highresolution acoustic Doppler current profiler and a SCAMP (temperature microstructure profiler to deliver information about turbulence). With this approach, we aim to explain the observed preferential vertical concentration of the target organisms (harmful or not). The field studies are complemented by physiological research in the laboratory which has already shown a particular sensitivity of dinoflagellates to small-scale turbulence. For hypothesis testing, we combine these field and laboratory observations with an individual based (Lagrangian) turbulence model. Here, we present some of our progress and highlight our future goals which includes the deployment of a real-time automated physico-optical observation system to provide a better understanding of the in situ biological (growth and grazing rate) dynamics of (harmful) phytoplankton.
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Llaveria G., E. Garcés, O.N. Ross, R.I. Figueroa, N. Sampedro, E. Berdalet
Marine Ecology Progress Series, 142, 45-56. DOI: 10.3354/meps08663 (BibTeX: llaveria.etal.2010)
Resum: Veure
Small-scale turbulence and parasite infection are 2 important factors that govern the dynamics and fate of phytoplankton populations. We experimentally investigated the influence of turbulent mixing on the infectivity of the parasite Parvilucifera sinerae to dinoflagellates. Natural phytoplankton communities were collected during 3 stages of a bloom event in Arenys de Mar Harbour (NW Mediterranean). The 15 to 60 µm size fraction was used as the inoculum and distributed into spherical flasks. Half of the recipients were exposed to turbulence while the rest were kept still. In the experiments, the dinoflagellate assemblage was mainly composed of Prorocentrum micans, Scrippsiella trochoidea and Alexandrium minutum. We observed a collapse of A. minutum and S. trochoidea populations in the unshaken flasks, which coincided with an increase in parasite infectivity. After a short exposure to turbulence, the development of the dinoflagellate populations slowed down and stabilised as expected. In the shaken treatments, the infectivity was lower and the decay in the host cells numbers was delayed compared to the still treatments. The degree of interference of the turbulence with infectivity varied among the experiments, due to differences in cell abundances and possibly their physiological state. Results from a numerical model suggest that turbulence could lead to a 25 to 30% decrease in the maximum infection rate, which could be due to host population dispersion and/or reduced host–parasite contact times. Turbulence may thus be effective in delaying the initial infection, but not in preventing it.
Paraules clau: Dinoflagellates · Infectivity · Parvilucifera sinerae · Parasite · Small-scale turbulence · Sporangia · Numerical model
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Llaveria G., R.I. Figueroa, E. Garcés, E. Berdalet
Journal of Phycology, 45, 5, 1106-1115. DOI: 10.1111/j.1529-8817.2009.00740.x (BibTeX: llaveria.etal.2009)
Resum: Veure
Decreased net population growth rates and cellular abundances have been observed in dinoflagellate species exposed to small-scale turbulence. Here, we investigated whether these effects were caused by alterations in the cell cycle and/or by cell mortality and, in turn, whether these two mechanisms depended on the duration of exposure to turbulence. The study was conducted on the toxic dinoflagellate Alexandrium minutum Halim, with the same experimental design and setup used in previous studies to allow direct comparison among results. A combination of microscopy and Coulter Counter measurements allowed us to detect cell mortality, based on the biovolume of broken cells and thecae. The turbulence applied during the exponential growth phase caused an immediate transitory arrest in the G2/M phase, but significant mortality did not occur. This finding suggests that high intensities of small-scale turbulence can alter the cell division, likely affecting the correct chromosome segregation during the dinomitosis. When shaking persisted for >4 d, mortality signals and presence of anomalously swollen cells appeared, hinting at the activation of mechanisms that induce programmed cell death. Our study suggests that the sensitivity of dinoflagellates to turbulence may drive these organisms to find the most favorable (calm) conditions to complete their division cycle.
Paraules clau: Alexandrium minutum; cell cycle; Coulter Counter; dinoflagellates; flow cytometry; G2/Mitosis; mortality; small-scale turbulence
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Llaveria G.,
PhD thesis. Director/es: . Elisa Berdalet i Andrés. (BibTeX: llaveria.2009)
Resum: Veure
Les proliferacions de dinoflagel·lades semblen estar relacionades sovint amb certa estabilitat de la columna d’aigua. Experiments de laboratori han mostrat que la turbulència de petita escala pot disminuir-ne la taxa de creixement i inhibir-ne la divisió cel·lular, juntament amb un augment de la mida i dels continguts d’ADN i ARN. L’objectiu de la present Tesis Doctoral fou explorar els efectes directes de la turbulència de petita escala en processos fisiològics relacionats amb el cicle cel·lular i de vida, i investigar els mecanismes pels quals aquest factor ambiental interfereix en la biologia de les dinoflagel·lades per contribuir així a la comprensió del desenvolupament de llurs proliferacions. Es va evidenciar que el cicle cel·lular de la dinoflagel·lada Alexandrium minutum es va aturar transitòriament en la fase G2/M. Les investigacions del possible mecanisme d’interferència per part de la turbulència varen considerar la hipòtesis d’una alteració del sistema microtubular implicat en la dinomitosi, la participació dels receptors de rianodina en la via de mecanotransducció activada per aquest estímul, i l’existència d’una expressió gènica diferencial. La turbulència va modular també la concentració cel·lular de toxines i de DMSP, la formació de cists d’ecdisi. i la infecció de l’endoparàsit Parvilucifera sinerae en dinoflagel·lades. La infectivitat va disminuir en condicions d’agitació i l’encistament asexual no va constituir un mecanisme útil per a la seva prevenció. També es va avaluar l’adequació de diversos sistemes experimentals per a generar turbulència en el laboratori. L’agitador orbital és el més idoni per a estudis fisiològics amb dinoflagel·lades, ja que tot el cultiu és exposat a la turbulència i les cèl·lules no se’n poden escapar. La present tesis doctoral conclou que les dinoflagel·lades prefereixen condicions de calma en la columna d’aigua, ja que la seva fisiologia és sensible a les situacions de mescla intensa.
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Guadayol Ò., F. Peters, C. Marrasé, J.M. Gasol, C. Roldán, E. Berdalet, R. Massana, A. Sabata
Marine Ecology Progress Series, 381, 139-155. DOI: 10.3354/meps07939 (BibTeX: guadayol.etal.2009)
Resum: Veure
In temperate coastal zones, episodic meteorological forcing can have a strong impact on the classical seasonal phytoplankton succession. Episodes of continental runoff and wind storms involve nutrient enrichment and turbulence, 2 factors that can promote primary production and alter the planktonic community species composition and size structure. We determined the joint influence of these 2 variables on the osmotrophic plankton of an oligotrophic NW Mediterranean open bay. We used an 8 yr long time series of monthly physical, chemical and biological water-column parameters, and we looked for correlations between these and several meteorological and physical high-frequency time series through cross-correlation analyses. Influence of river runoff in this particular location was found to be very important for phytoplankton dynamics, whereas no immediate response of bacterioplankton was detected. Resuspension events caused by waves had a secondary importance. Cross correlations allowed defining a sequence of responses to these types of forcing, from changes in water turbidity and salinity, to increases in phytoplankton and bacteria abundances through nutrient enrichments. The maximum response of the ecosystem in terms of chlorophyll a concentration lagged nutrient enrichment events by about 1 wk. A more detailed analysis was performed between June 2003 and June 2004, a period characterised by an intense drought in summer and by 6 strong meteorological events afterwards. The increase in the frequency of meteorological events during this period drove the system from heterotrophy to autotrophy. Our data stress the importance of episodic meteorological events in coastal planktonic communities.
Paraules clau: Episodic meteorological forcing · Coastal osmotrophic plankton · Waves · Terrestrial runoff · Sediment resuspension · Nutrients · Time series · NW Mediterranean
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Karlson B., R. Lopes, E. Berdalet, F. Chavez, S. Claus, K. Daly, S.A. Gaeta, C. Gallienne, J. Piera, S. Polat, O.N. Ross, N. Shams El Din, L. Valdes
, Ed. SCOR. 12. (BibTeX: karlson.etal.2009a)
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Guadayol Ò., C. Marrasé, F. Peters, E. Berdalet, C. Roldán, A. Sabata
Journal of Plankton Research, 31, 6, 583-600. DOI: 10.1093/plankt/fbp019 (BibTeX: guadayol.etal.2009b)
Resum: Veure
A year-long series of monthly experiments with laboratory enclosures were conducted with water from Blanes Bay (NW Mediterranean) to analyse the change in the short-time response of the osmotrophic planktonic community to simulated turbulence and nutrient input events. Both experimental factors triggered a relative increase of biomass in the enclosures, in terms of chlorophyll a, bacteria and particulate organic matter. Ratios of particulate organic nitrogen to phosphorus became lower in the water than in the sediment, although turbulence partially smoothed out this difference. Initial physico-chemical conditions significantly influenced the short-time responses to experimental forcing. The response to turbulence, in terms of chlorophyll a, was maximum in spring. The response to nutrient enrichment was found to be seasonal, and was correlated with photoperiod and temperature, and also in situ nitrate and silicate concentrations and Secchi depth, which are proxies of recent inputs of nutrients resulting from episodes of resuspension and river discharge. This study shows robust qualitative regularities in the response of the osmotrophic planktonic community to episodes of turbulence and nutrient enrichment, with quantitative variability throughout the year, depending mostly on the recent record of hydrodynamic forcing.
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, Ed. P. Gentien, B. Reguera, H. Yamazaki, L. Fernand, E. Berdalet, R. Raine (Eds.). 60. (BibTeX: .2008)
Resum: Veure
The Global Ecology and Oceanography of Harmful Algal Blooms (GEOHAB) programme was initiated in 1999 by the Scientific Committee on Oceanic Research (SCOR) and the Intergovernmental Oceanographic Commission (IOC) of UNESCO, to develop a research programme on the ecological and oceanographic mechanisms underlying the population dynamics of harmful algal blooms (HABs). The ultimate goal of this research is to allow the development of observation systems and models that will enable prediction of HABs, thereby reducing their impact on the health of humans and marine organisms, as well as their economic impact on society. The GEOHAB Implementation Plan (GEOHAB, 2003) specifies the formation of Core Research Projects (CRPs) related to four ecosystems types: upwelling systems, fjords and coastal embayments, eutrophic systems and stratified systems. These CRPs are initiated through small, focused open science meetings. The first Open Science Meeting (OSM)—HABs in Upwelling Systems, Lisbon, Portugal, 17–20 November 2003—focused on meso-scale hydrodynamic features (coastal upwelling zones). The second OSM— HABs in Fjords and Coastal Embayments, Viña del Mar, Chile, 26–30 April 2004—dealt with HAB events and their monitoring in semi-enclosed coastal systems, particularly non-eutrophied systems. The third OSM— HABs and Eutrophication, Maryland, USA, 7–10 March 2005—focused on high biomass HABs and their potential link with anthropogenic inputs. The fourth and last OSM—HABs in Stratified Systems, Paris, France, 5–8 December 2005—concentrated on small scale hydrographic features which may be encountered in any of the above mentioned environments. The present report outlines the justification and research priorities for the study of relationships between HABs and stratification, as well as some of the new approaches and advanced instrumentation that may be considered.
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Berdalet E., M. Estrada
In: Avances y tendencias en fitoplancton tóxico y biotoxinas : actas de la IX Reunión Ibérica sobre Fitoplancton Tóxico y Biotoxinas, Cartagena 7-10 de mayo de 2007., Ed. J. Gilabert. UPC. Universidad Politécnica de Cartagena. Chap. 1. 1-12. Cartagena. ISBN: 978-84-96997-06-6 (BibTeX: berdalet.estrada.2008)
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Thingstad T. F., H. Havskum, U.L. Zweifel, E.Berdalet, M.M. Sala, F. Peters, M. Alcaraz, R. Scharek, M. Perez, S. Jacquet, G.A.F. Flaten, J.R. Dolan, C. Marrasé, F. Rassoulzadegan, A. Hagstrøm, D. Vaulot
Journal of Marine Systems, 64, 1-4, 15-34. DOI: 10.1016/j.jmarsys.2006.02.009 (BibTeX: f.thingstad.etal.2007)
Resum: Veure
We compared an idealised mathematical model of the lower part of the pelagic food web to experimental data from a mesocosm experiment in which the supplies of mineral nutrients (nitrogen and phosphorous), bioavailable dissolved organic carbon (BDOC, as glucose), and silicate were manipulated. The central hypothesis of the experiment was that bacterial consumption of BDOC depends on whether the growth rate of heterotrophic bacteria is limited by organic-C or by mineral nutrients. In previous work, this hypothesis was examined qualitatively using a conceptual food web model. Here we explore the extent to which a “simplest possible” mathematical version of this conceptual model can reproduce the observed dynamics. The model combines algal bacterial competition for mineral nutrients (phosphorous) and accounts for alternative limitation of bacterial and diatom growth rates by organic carbon and by silicate, respectively. Due to a slower succession in the diatom copepod, compared to the flagellate ciliate link, silicate availability increases the magnitude and extends the duration of phytoplankton blooms induced by mineral nutrient addition. As a result, Si interferes negatively with bacterial consumption of BDOC consumption by increasing and prolonging algal bacterial competition for mineral nutrients. In order to reproduce the difference in primary production between Si and non-Si amended treatments, we had to assume a carbon overflow mechanism in diatom C-fixation. This model satisfactorily reproduced central features observed in the mesocosm experiment, including the dynamics of glucose consumption, algal, bacterial, and mesozooplankton biomass. While the parameter set chosen allows the model to reproduce the pattern seen in bacterial production, we were not able to find a single set of parameters that simultaneously reproduces both the level and the pattern observed for bacterial production. Profound changes in bacterial morphology and stoichiometry were reported in glucose-amended mesocosms. Our “simplest possible” model with one bacterial population with fixed stoichiometry cannot reproduce this, and we suggest that a more elaborate representation of the bacterial community is required for more accurate reproduction of bacterial production.
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Bolli L., G. Llaveria, E. Garcés, O. Guadayol, K. Van Lenning, F. Peters, E. Berdalet
Biogeosciences, 4, 4, 559-567. DOI: 10.5194/bg-4-559-2007 (BibTeX: bolli.etal.2007c)
Resum: Veure
Some dinoflagellate species have shown different physiological responses to certain turbulent conditions. Here we investigate how two levels of turbulent kinetic energy dissipation rates (ε = 0.4 and 27 cm² s−3) affect the PSP toxins and ecdysal cyst dynamics of two bloom forming species, Alexandrium minutum and A. catenella. The most striking responses were observed at the high ε generated by an orbital shaker. In the cultures of the two species shaken for more than 4 days, the cellular GTX(1+4) toxin contents were significantly lower than in the still control cultures. In A. minutum this trend was also observed in the C(1+2) toxin content. For the two species, inhibition of ecdysal cyst production occurred during the period of exposure of the cultures to stirring (4 or more days) at any time during their growth curve. Recovery of cyst abundances was always observed when turbulence stopped. When shaking persisted for more than 4 days, the net growth rate significantly decreased in A. minutum (from 0.25±0.01 day−1 to 0.19±0.02 day−1) and the final cell numbers were lower (ca. 55.4%) than in the still control cultures. In A. catenella, the net growth rate was not markedly modified by turbulence although under long exposure to shaking, the cultures entered earlier in the stationary phase and the final cell numbers were significantly lower (ca. 23%) than in the control flasks. The described responses were not observed in the experiments performed at the low turbulence intensities with an orbital grid system, where the population development was favoured. In those conditions, cells appeared to escape from the zone of the influence of the grids and concentrated in calmer thin layers either at the top or at the bottom of the containers. This ecophysiological study provides new evidences about the sensitivity to high levels of small-scale turbulence by two life cycle related processes, toxin production and encystment, in dinoflagellates. This can contribute to the understanding of the dynamics of those organisms in nature.
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Catalán I.A., E. Berdalet, M.P. Olivar, C. Roldán
Journal of Fish Biology, 70, 2, 391-405. DOI: 10.1111/j.1095-8649.2007.01307.x (BibTeX: catalan.etal.2007)
Resum: Veure
Six condition indices based on RNA, total soluble protein and two metabolic enzymes [lactate dehydrogenase (LDH) and citrate synthase (CS)] were analysed in muscle tissue of individual larvae, post-flexion reared sea bass Dicentrarchus labrax using DNA and total soluble protein as standards for size. In addition, the effect of 2 days of food deprivation on the cell proliferation rates was assessed. The RNA:DNA best reflected short-term changes in feeding conditions. If standardized by DNA content, LDH activity was a better indicator of condition than any other index but RNA:DNA. Further, the analysis of cell proliferation rates in muscle from 26 day-old larvae proved useful in distinguishing continuously fed larvae from individuals subjected to 2 days of fast.
Paraules clau: cell proliferation rates; condition; Dicentrarchus labrax larvae; metabolic enzymes; RNA:DNA
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Berdalet E., F. Peters, V. Lila Koumandou, C. Roldan, O. Guadayol, M. Estrada
Journal of Phycology, 43, 965-977. DOI: 10.1111/j.1529-8817.2007.00392.x (BibTeX: berdalet.etal.2007)
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Peters F., L. Arin, C. Marrasé, E. Berdalet, M.M. Sala
Journal of Marine Systems, 61, 134-148. (BibTeX: peters.etal.2006b)
Resum: Veure
The effect of turbulence on the nutrient flux towards osmotrophic cells is predicted to be size dependent. This should translate into growth. We experimentally followed and modelled the growth of two marine diatoms of different size (Thalassiosira pseudonana, 6 mu m in diameter and Coscinodiscus sp., ca. 109 mu m in diameter) under still water and turbulent conditions, using a shaker table. Experiments were done with phosphorus-limited cultures and lasted for ca. 5 days. Turbulence enhanced the growth of Coscinodiscus sp. in agreement with theory but not the growth of T pseudonana, which was actually slightly lower under turbulence. At the end of the experiments there were about 1.7 times as many. Coscinodiscus sp. cells in the turbulent treatment than in the still treatment, while for T pseudonana almost the same cell concentration was found in both conditions. In addition, the Coscinodiscus sp. cells growing under still conditions presented a higher specific alkaline phosphatase activity than those growing in turbulence which indicates a higher need for phosphorus in the still cultures. A simple dynamic model, based on Michaelis-Menten nutrient uptake kinetics, needed nearly no optimisation other than using observed initial conditions of phosphate and cell concentrations. The model showed how an increased nutrient flux towards the cells translates non-linearly into cell growth, most likely by affecting the half-saturation constant (K-M). However, since Coscinodiscus sp. experienced significant mortality and cells partially settled to the bottom of the containers, unequivocal support for the size-dependent effect of turbulence on nutrient uptake will require further experiments and more sophisticated modelling. The mechanisms to connect an increased nutrient flux towards cells with population growth and whether this process is size dependent are important in parameterizing the effects of turbulence on marine plankton in coupled physical-biological models. (c) 2006 Elsevier B.V. All rights reserved.
Paraules clau: diatom growth, half saturation constant, maximum uptake velocity, nutrient uptake, phosphorus affinity, size, turbulence
Effects of small-scale turbulence on the physiological functioning of marine microalgae (2006)
Berdalet E., M. Estrada
In: Algal, cultures, analogues of blooms and applications, Vol. 2. Ed. D.V.Subba Rao. Science Publishers. 459-500. Enfield (NH) USA. ISBN: 1-57808-394-X
Effects of Small-scale Turbulence on the Physiological Functioning of Marine Microalgae (2006)
Berdalet E., M. Estrada
In: Algal Cultures, Analogues of Blooms and Applications, Vol. 2. Ed. D.V. Subba Rao. Bedford Institute of Oceanography, Dartmouth, NS, Canada. Science Publishers. 1016. Enfield. ISBN: 978-1-57808-393-0
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Caldarone E.M., C.M. Clemmesen, E. Berdalet, T. J. Miller, A. Folkvord, G.J. Holt, M.P. Olivar, I.M. Suther
Limnology and Oceanography : Methods, 4, 153-163. DOI: 10.4319/lom.2006.4.153 (BibTeX: caldarone.etal.2006)
Resum: Veure
The ratio of tissue RNA to DNA (R/D) is a widely used index of recent growth and nutritional condition in larval and juvenile fish. To date, however, no standard technique for measuring nucleic acids has been adopted. Because methodological details can affect the estimate of R/D, researchers using different analytical protocols have been unable to compare ratios directly. Here, we report on the results of an international interlaboratory calibration of 4 spectrofluorometric protocols to quantify nucleic acids. Replicate sets of 5 tissue samples and 2 standards (common standards) were supplied to each of 5 researchers for analysis with their own methods and standards. Two approaches were evaluated for mitigating the observed differences in values: 1) the use of common nucleic acid standards and 2) standardizing to a common slope ratio (slope of DNA standard curve/slope of RNA standard curve or mDNA/mRNA). Adopting common standards slightly reduced the variability among protocols but did not overcome the problem. When tissue R/Ds were standardized based on a common mDNA/mRNA slope ratio, the variance attributed to analytical protocol decreased dramatically from 57.1% to 3.4%. We recommend that the ratio of the slopes of the standard curves be provided to facilitate intercomparability of R/D results among laboratories using different spectrofluorometric methods for the analysis of nucleic acids in fish.
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Catalán I.A., M.P. Olivar, I. Palomera, E. Berdalet
Marine Ecology Progress Series, 307, 219-231. DOI: 10.3354/meps307219 (BibTeX: catalan.etal.2006a)
Resum: Veure
Relationships between environmental factors and the growth and condition of pilchard Sardina pilchardus (Walbaum) larvae were studied in November 1998 in the northwestern Mediterranean(NWM). Long-term growth of fish was assessed using otolith analysis and condition was assessed through histological and biochemical (RNA/DNA) indices. These measurements were conducted on larvae belonging to 2 station groups (A and B) previously defined through principal component analysis (PCA) on 7 environmental variables. Correlations between individual condition indices and environmental values at place of capture were also performed. Condition in environmental group A was significantly higher than in group B as assessed by both histological indices and RNA/DNA. Long-term growth, however, did not differ significantly between groups except for the otolith diameter vs. standard length (SL) relationship. The stations conforming to environmental group A were characterised by environmental ranges that would form a favorable habitat for larval success, including surface temperatures <19°C, relatively low stratification (maximum Brunt Väissälä, B-V, <0.8 cycles h-1) and mean potential food abundance >4500 nauplii(N) m-3 or >5500 of other microzooplankters (T-N) m–3. Apart from the good agreement found between histological and RNA/DNA results, each approach offered different information: histological indices detected the largest portion of unfit larvae at size-ranges ≤8 mm, whereas RNA/DNA best discriminated large larvae. The results from this study support the view that links exist between mesoscale anomalies, spawning intensity and growth or condition of pilchard larvae in the NWM.
Paraules clau: Sardina pilchardus, Larvae, Environment, Condition, Growth, Northwestern Mediterranean
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Havskum H., P.J. Hansen, E. Berdalet
Limnology and Oceanography, 50, 5, 1543-1551. (BibTeX: havskum.etal.2005)
Resum: Veure
We investigatedth e effect of naturale vels of turbulenceo n the verticald istributiona nd net populationg rowth of the dinoflagellateC eratiumt riposa nd on the interactionw ith its predatort,h e mixotrophicd inoflagellatFe ragilidiums ubglobosumU. nialgalc ultureso f each species were exposedt o four kinetice nergyd issipationr ates,e : 0.0001, 0.01, 0.05, and 1 cm2s -3, generatedb y verticallyo scillatingg ridsi n 2-literc ylindricc ontainersA. utotrophic growtho f F. subglobosumw as not affectedb y any level of turbulenctee sted.I n contrasta, t s > 0.05 cm2s -3 (this value is generatedin the upper1 0 m of the ocean by a moderateg ale or at 0.5 m in depthb y a gentleb reeze),C . triposd ecreasedi ts net populationg rowth,a nd the verticald istributiono f the cells was affected.A t the highest turbulencele vel, C. triposs toppeds wimming,s ettled,a nd accumulateda t the bottom.M ixotrophicg rowtho f F. subglobosumw, hen fed C. tripos at high densities( i.e., >10 prey cells mL-1), was not affectedb y turbulence. However,a t low preyc ell densities( i.e., 5 to 8 C. triposc ells mL-'1)g, rowtha ndi ngestionr ateso f F. subglobosum were significantlyh ighera t the highestt urbulencele vel comparedto the ratesa t othert urbulencele vels and were close to the ratesm easureda t high preyc ell densities,p resumablby ecauses edimentatioonf C. triposc ells resulted in patchesw heret he cell densitiesw ere not food-limitingfo r F. subglobosum.
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Berdalet E., C. Roldán, M.P. Olivar, K. Lysnes
Scientia Marina, 69, 1, 1-16. (BibTeX: berdalet.etal.2005c)
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Berdalet E., C. Roldán, M.P. Olivar
Scientia Marina, 69, 1, 17-30. (BibTeX: berdalet.etal.2005b)
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Berdalet E., C. Roldán, M. Latasa, C. Marrasé, M. Vidal, M. Estrada, A. Malits, J. Salat, M. Emelianov, A. Sabatés
, Rapports et Proces-verbaux des Réunions. Com. Int. Explor. Sci. Mer Mediterranée, CIESM.. Ed. CIESM. CIESM. 37, 313. Montecarlo (Monaco). ISSN: 0373-434X (BibTeX: berdalet.etal.2004d)
Resum: Veure
We studied physico-chemical (temperature, salinity, inorganic nutrients) and biological (phytoplankton pigment composition, bacterial numbers, protein, DNA, RNA, and POM) characteristics of a hydrographically diverse area of the northern Catalan sea during the stratification period (June 2000). The sampled stations were affected by a) continental shelf (coastal waters), and b) low salinity surface waters from the Gulf of Lions influenced by the Rhone runoff (called Plume), carried by the shelf-slope Catalan current. We compared these areas with oceanic waters. The relative fertilising effect of the Plume for the plankton communities is discussed
Paraules clau: nutrients, pigments, plankton, Rhone plume
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Havskum H., L. Schlüter, R. Scharek, E. Berdalet, S. Jacquet
Marine Ecology Progress Series, 273, 31-42. DOI: 10.3354/meps273031 (BibTeX: havskum.etal.2004)
Resum: Veure
Phytoplankton pigments in samples taken from nutrient-enriched and non-enriched 3 m3 seawater enclosures were separated and quantified using high-performance liquid chromatography (HPLC). The enclosures were with and without inorganic (N, P, Si) and organic (glucose, C) nutrient enrichments, resulting in a variation of phytoplankton groups in time and space. The relative contribution of the major phytoplankton groups to the total chlorophyll a (i.e. chlorophyll a plus chlorophyllide a) was estimated by the CHEMTAX program. The results were compared to phytoplankton groups identified and quantified by light and epifluorescence microscopy. For the pigmented flagellate groups the results obtained by microscopy and pigment analyses using the CHEMTAX program showed similar trends. The picocyanobacteria were readily quantified by microscopy and the results were similar to those obtained by flow-cytometry, while the CHEMTAX program for the cyanobacteria revealed different trends. Microscopy and pigment analyses provided similar trends in diatom population development. Estimated diatom contributions to total phytoplankton biomass, however, were considerably higher when based on microscopy than when based on the CHEMTAX program, especially in Si-amended enclosures. Total chlorophyll a:carbon ratios for diatoms were at the lower end of a previously reported range between 1:27 and 1:67. For the pigmented flagellate groups the total chlorophyll a:carbon ratios were above that range. In routine monitoring of phytoplankton we recommend the use of the CHEMTAX program based on HPLC pigment analyses accompanied by a screening for the dominating species by microscopy, and by flow-cytometry for quantification of picocyanobacteria.
Paraules clau: HPLC pigment analyses · CHEMTAX program · Microscopy · Chlorophyllide a · Chlorophyll a:carbon ratios · Pigmented flagellates · Cyanobacteria · Diatoms
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Catalán I.A., M.P. Olivar, I. Palomera, E. Berdalet, C. Roldán, B. Aguilera
Rapports et Proces-verbaux des Réunions. Com. Int. Explor. Sci. Mer Mediterranée, CIESM., 37, 330. (BibTeX: catalan.etal.2004)
Resum: Veure
the long- and short-term growth of 3.5 to 16 mm standard length Sardina pilchardus larvae was compared between two cruises conducter in autumn and winter in the Catalan Sea (NW Mediterranean). Growth was significantly higher in November than February, as assenssed by muscle fibre recruitment and RNA/DNA ratios. Otolith age-length relationships suggested a similar trend. Sea temperature is regarded as a plausible explanatory factor for the differences in growth.
Paraules clau: Sardina pilchardus, larvae, growth, NW Mediterranean, temperature
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Estrada M., E. Berdalet, M. Vila, C. Marrasé
Aquatic Microbial Ecology, 32, 1, 61-71. DOI: 10.3354/ame032061 (BibTeX: estrada.etal.2003)
Resum: Veure
A microcosm experiment was carried out during early spring 1994 in order to investigate the effect of Si-sufficient but low N:P ratio or high N:P ratio nutrient inputs, added at different frequencies, on phytoplankton succession patterns. Eight Perspex cylinders were filled with 30 l of coastal water from Masnou (20 km north of Barcelona) and placed in a chamber at 17°C under a 12:12 h light:dark photoperiod. Four experimental conditions were randomly assigned to duplicate containers: low N:P ratio (N-deficient) or high N:P ratio (P-deficient) nutrient inputs (including sufficient Si in all cases), in combination with addition intervals of 2 or 6 d. Integrated chlorophyll a (chl a) concentrations in the P-deficient containers were significantly higher than in the N-deficient ones, presumably due to the faster recycling of P with respect to N, but differences between addition intervals were non-significant. All microcosms presented an initial bloom dominated by diatoms. In the post-bloom phase, after depletion of the nutrient in short supply, dinoflagellate abundances were higher and diatom abundances lower in the N-deficient than in the P-deficient microcosms. Within nutrient treatments, the qualitative composition of the phytoplankton assemblages was similar across frequencies and replicates. In contrast, characteristics, such as total phytoplankton biovolume or the abundance of dominant taxa, presented significant variability, presumably due to non-linear interactions, even within replicates. This finding suggests the importance of focussing on assemblages rather than on individual taxa when attempting to derive regularities concerning the response of phytoplankton to environmental factors.
Paraules clau: NW Mediterranean · Nitrogen · Phosphorus · Nutrient ratios · Chlorophyll a concentration · Phytoplankton biomass · Phytoplankton succession · Phytoplankton assemblages
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Havskum H., T.F. Thingstad, R. Scharek, F. Peters, E. Berdalet, M.M. Sala, M. Alcaraz, J.C. Bangsholt, U.L. Zweifel, A. Hagström, M. Perez, J.R. Dolan
Limnology and Oceanography, 48, 1, 129-140. (BibTeX: havskum.etal.2003)
Resum: Veure
The effects of organic and inorganic nutrient enrichments on algal-bacterial competition were investigated using mesocosms. Interactions were followed over 10 d in 12, 3-m3 seawater mesocosms in the Isefjord, Denmark. Two sets of four mesocosms were given the same daily addition of "phytoplankton nutrients" (phosphate and nitrate) but received different amounts of glucose, and one set was kept in excess with respect to silicate. Four additional mesocosms served as controls and received either no additions, silicate alone, or glucose alone. In the mesocosm set where no silicate was added, enrichment with phytoplankton nutrients and glucose led to a replacement of diatoms, not by other algae, but by heterotrophic bacteria, mainly bacteria > 2 /,m. In the mesocosm set where silicate was kept replete, diatoms competed successfully with bacteria for the uptake of mineral nutrients. Even in mesocosms enriched with high amounts of glucose, primary production increased throughout the experimental period, while bacterial production, after an initial increase, leveled off. In addition, turnover time of glucose increased in the silicate-replete mesocosm set, consistent with the idea that bacterial consumption was hampered by diatoms competing successfully for phosphate and nitrate. The size and shape of different algal and bacterial groups in relation to nutrient uptake and grazer avoidance are discussed. Both accumulation and consumption of dissolved organic carbon could depend on the structure of the microbial food web.
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Berdalet E.,
In: Pelagic ecology methodology, Ed. D. V. Subba Rao, P. N. Ganapati, Eugene Cecil LaFond, George F. Humphrey. CRC Press. Chap. 26. 271-290. ISBN: 9789058092663 (BibTeX: berdalet.2002)
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Anderson D.M., D.M. Kulis, B.A. Keafer, E. Berdalet
Journal of Phycology, 35, 4, 870-883. DOI: 10.1046/j.1529-8817.1999.3540870.x (BibTeX: anderson.etal.1999)
Resum: Veure
The toxic dinoflagellate Alexandrium fundyense Balech was grown under temperature- and nutrient-limited conditions, and changes in labeling intensity on intact cells were determined for two probe types: an oligonucleotide probe targeting rRNA and a monoclonal antibody (MAb) targeting a cell surface protein. In nutrient-replete batch culture, labeling with the rRNA probe was up to 400% brighter during exponential phase than during stationary phase, whereas MAb labeling did not change significantly with growth stage at the optimal growth temperature. In cultures grown at suboptimal, low temperatures, there was a significant difference between labeling intensity in stationary versus exponential phase for both probe types, with exponential cells labeling brighter with the rRNA probe and slightly weaker with the MAb. The decrease in rRNA probe labeling with increasing culture age was likely due to lower abundance of the target nucleic acid, as extracted RNA varied in a similar manner. With the MAb and the rRNA probes, slower growing cultures at low, nonoptimal temperature labeled 35% and 50% brighter than cells growing faster at warmer temperatures. Some differences in labeling intensity per cell disappeared when the data were normalized to surface area or volume, which indicated that the number of target antigens or rRNA molecules was relatively constant per unit area or volume, respectively. Slow growth accompanying phosphorus and nitrogen limitation resulted in up to a 400% decrease in labeling intensity with the rRNA probe compared to nutrient-replete levels, whereas the MAb labeling intensity increased by a maximum of 60%. With both probes, labeling was more intense under phosphorus limitation than under nitrogen limitation, and for all conditions tested, labeling intensity was from 600% to 3600% brighter with the MAb than with the rRNA probe. Thus, it is clear that significant levels of variability in labeling intensity can be expected with both probe types because of the influence of environmental conditions and growth stage on cellular biochemistry, cell size,rRNA levels, and the number or accessibility of cell surface proteins. Of the two probes tested, the rRNA probe was the most variable, suggesting that in automated, whole-cell assays, it can be used only in a semiquantitative manner. For manual counts, the human eye will likely accommodate the labeling differences. The MAb probe was less variable, and thus should be amenable to both manual and automated counts.
Paraules clau: Alexandrium; antibody; oligonucleotide; physiology; probe; rRNA
Doval M.D., F.F. Perez, E. Berdalet
Deep-Sea Research. Part I: Oceanographic Research Papers, 46, 3, 511-527. DOI: 10.1016/S0967-0637(98)00072-7 (BibTeX: doval.etal.1999)
Resum: Veure
The distribution of dissolved organic carbon (DOC) and nitrogen (DON) and particulate organic carbon (POC) and nitrogen (PON) was studied on a transect perpendicular to the Catalan coast in the NW Mediterranean in June 1995. The transect covered a hydrographically diverse zone, including coastal waters and two frontal structures (the Catalan and the Balear fronts). The cruise was conducted during the stratified period, characterized by inorganic nutrient depletion in the photic zone and a well established deep chlorophyll a maximum. DOC concentrations were measured using a high-temperature catalytic oxidation method, and DON was determined directly, with an update of the Kjeldahl method, after removal of inorganic nitrogen. The ranges of DOC and DON concentrations were 4495 μM-C and 2.86.2 μM-N. The particulate organic matter ranged between 0.9 and 14.9 μM-C and from 0.1 to 1.7 μM-N. The DOC : DON molar ratio averaged 15.50.4, and the mean POC : PON ratio was 8.60.6. The distribution of dissolved organic matter (DOM) was inverse to that of the salinity. The highest concentrations of DOM were found in coastal waters and in the stations affected by the Catalan front, located at the continental shelf break. It was estimated that recalcitrant DOM constituted 67% of the DOM pool in the upper 50 m. The data suggest that accumulation of DOC due to the decoupling of production and consumption may occur in the NW Mediterranean during stratification and that the organic matter exported from the photic layer is dominated by C-rich material
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Roy S.O., T.T. Packard, E. Berdalet, L. St-Amand
Aquatic Microbial Ecology, 17, 105-110. DOI: 10.3354/ame017105 (BibTeX: roy.etal.1999)
Resum: Veure
Physiological rates of CO2 production and O2 consumption, and the activities of isocitrate dehydrogenase (IDH) and the electron transfer system (ETS) were studied in the marine bacterium Pseudomonas nautica growing on acetate. In exponential growth, IDH and ETS activities were well coupled with CO2 production and O2 consumption rates, but in senescence they were uncoupled. Our results clearly show that under starvation conditions, IDH and ETS activities remained high even though their corresponding respiration rates dropped. The respiratory metabolism in the different physiological states of the acetate-grown cultures was compared with previous observations made in pyruvate-grown cultures. Time profiles of CO2 production and O2 consumption rates showed completely different respiratory fingerprints associated with the different carbon sources. Acetate-grown cultures showed an increase of respiratory quotients (RQ) in the senescence phase whereas in pyruvate-grown cultures it stayed close to 1.0. On both carbon sources, respiration to respiratory capacity ratios were constant in exponential phase and decreased to almost zero after carbon source exhaustion. Our results clearly show the impact of physiological state and carbon sources on bacterial respiration rates.
Paraules clau: CO2 production rates · O2 consumption rates · Isocitrate dehydrogenase · Respiratory electron transfer system · ETS · Marine bacterium
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Arin L., E.E. Berdalet, C. Marrasé, M. Estrada, N. Guixa-Boixereu, J. Dolan
Journal of Plankton Research, 21, 7, 1299-1316. DOI: 10.1093/plankt/21.7.1299 (BibTeX: arin.etal.1999)
Resum: Veure
Using microscopic and biochemical approaches, the relative contribution of the main groups of pelagic microorganisms (bacteria, heterotrophic nanoflagellates, phytoplankton and ciliates) and detritus (<150m) to total particulate protein and DNA was investigated at two stations of the Catalano-Balearic Sea (NW Mediterranean) during the stratified period. The two stations, one located in the shelf break front (S) and the other in the open sea, above the central divergence zone (D), were sampled twice in early summer 1993. Both of them showed a well-developed deep chlorophyll maximum (DCM). Maximum DNA concentrations were observed close to the DCM, while protein concentrations were fairly homogeneous from the surface to 60 m depth in all samplings. In general, the microorganism distribution showed maximum concentrations at or near the DCM depths. At both stations, bacteria were the most important contributors to living particulate DNA (22.5-32.6%), while phytoplankton and heterotrophic nanoflagellates were the main contributors to living particulate protein (3.8-24.4 and 2.9-29.1%, respectively). In addition, an important amount of detrital DNA and protein was estimated to occur at both stations. Detrital DNA accounted for 23.9-42.9% of the particulate DNA, while detrital protein represented from 63.5 to 84.7% of the particulate protein. Because both protein and DNA contain nitrogen and DNA is also a phosphorus source, these results indicate that heterotrophic organisms and detrital particles play an important role in the nitrogen and phosphorus cycles in the open sea waters of the NW Mediterranean.
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Estrada M., E. Berdalet
In: Physiological ecology of harmful algal blooms, Series G: Ecological Series. Vol. 41. Ed. D. M. Anderson, A.D. Cembella & G. M. Halleagraaf (eds.). 601-618. ISBN: 978-3540641179 (BibTeX: estrada.berdalet.1998)
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Saiz E., A. Calbet, A . Fara, E. Berdalet
Limnology and Oceanography, 43, 3, 465-470. (BibTeX: saiz.etal.1998)
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Berdalet E., D. Vaqué, L. Arín, M. Estrada, M. Alcaraz, J.A. Fernández
Polar Biology, 17, 1, 31-38. DOI: 10.1007/s003000050102 (BibTeX: berdalet.etal.1997)
Resum: Veure
 The relationships between hydrography and spatial distribution of several biochemical indicators of microplankton biomass (chlorophyll, protein and ATP) were studied in an area covering the eastern part of the Bransfield Strait and the northern part of the Weddell Sea, during Antarctic summer (January 1994). Four hydrographic zones were identified: (a) the northern part of the Bransfield Strait, covered by waters of Bellings- hausen Sea origin; (b) a Weddell Sea water mass that affected most of the study area; (c) the Weddell-Scotia Confluence waters, observed north of Elephant Island; and (d) waters influenced by ice melting, found towards the southeastern part of the sampled area. The highest values of biomass indicators (chlorophyll a, ATP and protein) were found in the zones affected by ice-melting processes and in waters from the Bellingshausen Sea. The lowest values of all biochemical parameters were found in the Weddell Sea and in the Weddell-Scotia Confluence waters. A high variability in the hydrographic structure and the distribution of biochemical indicators was observed. The degree of stabilization of the water column, the depth of the upper mixed layer and the grazing pressure of herbivorous zooplankton played a major role in the development, accumulation and spatial variability of microplankton biomass.
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Estrada M., E. Berdalet
Scientia Marina, 61, suppl.1, 125-140. (BibTeX: estrada.berdalet.1997)
Resum: Veure
This contribution reviews relationships between turbulence and marine phytoplankton ecology, ranging from the mesoscale to the smallest scales. Phytoplankton life-forms, considered to be survival strategies in a turbulent environment, are briefly presented. The importance of mesoscale hydrodynamics on phytoplankton distributions and organisms physiology and behaviour, are examined. Finally, direct effects of small scale turbulence on phytoplankton are considered.
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Packard T., E. Berdalet, D. Blasco, S.O. Roy, L. St-Amand, B. Lagacé, K. Lee, J.-P. Gagné
Aquatic Microbial Ecology, 11, 1, 11-19. DOI: 10.3354/ame011011 (BibTeX: packard.etal.1996a)
Resum: Veure
CO2 production in aerobic bacteria was modeled from the time- courses of the in vitro activity of isocitrate dehydrogenase (IDH), bacterial protein, and the concentration of the carbon source in the cultures. The model was based on the concept of bisubstrate control of the IDH reaction through out the exponential, steady-state, and senescent phases of the cultures. In the exponential phase, the measured rates of CO2 production and the in vitro IDH activity were closely coupled, but in the senes-cent phase, they became uncoupled. The in vitro IDH activity remained high even after the culture's carbon source was exhausted, while the CO2 production fell to low levels. Based on the hypothesis that this uncoupling was caused by internal substrate limitation, 2 mathematical models incorporating a bisubstrate enzyme kinetics algorithm were constructed and tested. The models predicted the rate of CO2 production throughout the different phases of the cultures with an r(2) greater than 0.84.
Fara A., Berdalet, L. Arin
Journal of Phycology, 32, 6, 1074-1083. DOI: 10.1111/j.0022-3646.1996.01074.x (BibTeX: fara.etal.1996)
Resum: Veure
A fluorometric technique, based on the combination of RNase and DNase incubation with the use of thiazole orange (RNase/DNase method), was investigated to determine DNA and RNA concentrations in marine plankton. Tests were performed to optimize both RNase and DNase assay conditions. The RNase assay should be conducted at 37° C for 20 min with 0.5 μg·mL−1 of DNase-free RNase. An incubation at 25° C for 20 min with 10 units ·mL-1 of RNase-free DNase were the optimal conditions required for DNA digestion by DNase. The detection limits in terms of minimum biomass for reliable measurements of DNA and RNA were 7.5 and 10 μg of protein · (mL assay)−1, respectively. RNA and DNA concentration were estimated in oligotrophic water samples using the RNase/DNase and other available methods (e.g. a double fluorochrome method). The different techniques provided similar DNA estimations. However, the RNase/DNase method provided the highest sensitivity and a low variability for the estimation of RNA.
Paraules clau: DNA quantification; fluorometric techniques; natural plankton; phytoplankton; RNA quantification; thiazole orange
Effect of different nutrient combinations on phytoplankton development in microcosms (1996)
Estrada M., E. Berdalet, C. Marrasé, L. Arin, M.L. Mclean
In: Harmful and Toxic Algal Blooms, Intergovernamental Oceanographic Commission of UNESCO. Ed. T. Yasumoto, Y. Oshima and Y. Fukuyo (eds). 297-300.
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Berdalet ., E., C. Marrasé, M. Estrada, L. Arin, M.Maclean
Journal of Plankton Research, 18, 9, 1627-1641. DOI: 10.1093/plankt/18.9.1627 (BibTeX: .etal.1996a)
Resum: Veure
Natural plankton communities from Masnou, a locality 20 km north of Barcelona (NW Mediterranean coast), were enclosed in 30 l microcosms to test the effect of different availability of nitrogen (N) and phosphorus (P) on the biomass of the main microplankton groups, and the biochemical composition (DNA, protein and chlorophyll concentration) of microbial communities. Immediately after enclosure in microcosms, three different nutrient enrichments were performed: N-deficient, P-deficient and nutrient-balanced. N and P deficiencies affected the structure and the biochemical composition of the microbial communities. Phytoplankton assemblages showed similar temporal patterns under the three nutrient treatments, although the relative contribution of the different groups was notably affected. The lowest DNA concentration was measured in the P-deficient treatment, suggesting that P availability imposes the limits on the DNA levels in the ecosystem. The availability of N in the P-deficient microcosms allowed relatively high synthesis of chlorophyll and protein until the end of the experiment. Significantly high chlorophyll: DNA and protein: DNA ratios characterized the P-deficient treatment (where N was available) compared to the N-deficient microcosms. From the results obtained, we suggest that the protein: DNA ratios may constitute a biochemical indicator of the P versus N availability in natural ecosystems.
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Packard T.T., E. Berdalet, D. Blasco, S.O. Roy, L. St-Amand, B. Lagacé, K. Lee, J.-P. Gagné
Journal of Plankton Research, 18, 10, 1819-1835. DOI: 10.1093/plankt/18.10.1819 (BibTeX: packard.etal.1996b)
Resum: Veure
The respiratory O2 consumption in aerobic bacterial cultures has been modeled from the time profiles of the in vitro activity of the respiratory electron transfer system (ETS), the bacterial protein and the concentration of the carbon source in the cultures. The model was based on the concept of bisubstrate kinetic control of the ETS throughout the exponential, steady-state and senescent phases of the cultures. In the exponential phase, the measured rates of O2 consumption and the in vitro ETS activity were closely coupled, but in the senescent phase, they were uncoupled. The in vitro ETS activity remained high even after the culture's carbon source was exhausted, while the O2 consumption fell to low levels. Based on the hypothesis that this uncoupling was caused by limitation of the intracellular ETS substrates (NADH and NADPH), a semi-empirical model incorporating a bisubstrate enzyme kinetics algorithm was formulated and fitted to the observations of the experiments. The model predicted the rate of O2 consumption throughout the different phases of the cultures with an r2 > 0.92 (n = 9, P < 0.001) using physiologically realistic Michaelis and dissociation constants. These results suggest that plankton respiration in the field could be assessed more accurately than before by measuring the intracellular ETS substrates (NADH and NADPH), in addition to ETS activity, in plankton.
Berdalet E., T. Packard, B. Lagacé, S. Roy, L. St-Amand, J.P. Gagné
Aquatic Microbial Ecology, 9, 3, 211-217. DOI: 10.3354/ame009211 (BibTeX: berdalet.etal.1995)
Resum: Veure
The respiratory metabolism of the marine bacterium Vibrio natriegens growing in batch cultures with acetate and pyruvate as carbon sources was studied. In particular, the relationship of the activity of the enzyme isocitrate dehydrogenase (IDH) to physiological CO2 production and O-2 consumption was examined. Gas measurements were performed by a new type of respirometer that combined O-2 detection by a Pb-O fuel cell and CO2 detection by infrared absorption. Two different respiratory patterns were observed. On pyruvate, CO2 production and O-2 consumption rates paralleled each other during the exponential and the stationary phases. On acetate, they did not. Growth based on acetate was characterized by a higher O-2 consumption, lower CO2 production, lower respiratory quotient and lower IDH activity than on pyruvate. In both culture media, the in vitro IDH activity remained elevated after the in vivo CO2 production had decreased when the carbon source was exhausted. The range of the respiratory quotient obtained in the acetate cultures suggests that the acetate is partitioned between the Krebs cycle and the glyoxylate bypass in the proportions of 1:4 to 1:2. In the pyruvate cultures, the range of the respiratory quotients indicates that, in the course of the different growth phases, the partitioning of the carbon source between the Krebs cycle and the anaplerotic pathways is variable.
Latasa M., E. Berdalet
Journal of Plankton Research, 16, 1, 83-94. DOI: 10.1093/plankt/16.1.83 (BibTeX: latasa.berdalet.1994)
Resum: Veure
The effect of nitrogen (N) and phosphorus (P) depletion on the cell volume and pigment composition of the marine dinoflagellate Heterocapsa sp. was studied. Cell size increased under both N or P starvation, but the change was faster when P was limiting. Quantitatively. N deficiency resulted in greater pigment loss than did P deficiency, thereby corroborating the relationship between pigment synthesis and N metabolism. It is suggested that the synthesis of pigments is primarily stopped at a transcriptional level (from DNA to RNA) under P limitation and at a translational level (from RNA to proteins) under N limitation. Almost all pigments underwent a parallel decrease during the stationary phase and no clear changes in pigment ratios were found. As an exception, a pigment identified as diatoxanthin accumulated in the algae when cell growth ceased. This occurred regardless of the growth-limiting nutrient and became more pronounced as cell deterioration progressed.
Berdalet E., M. Latasa, M. Estrada
Journal of Plankton Research, 16, 4, 303-316. DOI: 10.1093/plankt/16.4.303 (BibTeX: berdalet.etal.1994)
Resum: Veure
Changes in the protein, RNA and DNA content related to nitrogen (N) and phosphorus (P) starvation were studied in the marine dinoflagellate Heterocapsa sp. grown in batch cultures. In both cases of nutrient starvation, metabolic adaptations affected protein and RNA pools, while the DNA content per cell remained approximately constant. N starvation led to a parallel decrease in protein and RNA concentration which caused the protein/RNA ratios to remain constant. A dramatic decrease in the RNA content characterized the P-starved cultures, although protein synthesis continued. The ribosomal RNA content was lower than expected given the continuation of protein synthesis. It is suggested that protein/RNA ratios could be used as an indicator of P starvation, while protein/chlorophyll ratios would characterize N starvation
Effects of turbulence on several dinoflagellate species. (1993)
Berdalet E., M. Estrada
In: In Toxic Phytoplankton Blooms in the Sea edited by T. J. Smayda and Y. Shimizu, Ed. T. J. Smayda and Y. Shimizu. 734-737.
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Berdalet E., M. Estrada
Marine Biology, 117, 1, 163-170.. DOI: 10.1007/BF00346439 (BibTeX: berdalet.estrada.1993)
Resum: Veure
We explored the relationships between classical estimators of autotrophic biomass and primary production, such as chlorophyll a concentration and 14C-fixation rates, and biochemical indices based on DNA and RNA determinations, which have been proposed as indicators of physiological state in natural plankton populations. The measurements were made during two cruises across the Catalan Front, carried out in May 1989 and February 1990, corresponding respectively, to periods of stratification and moderate mixing. DNA and RNA concentrations (measured by a double-staining fluorimetric technique) were significantly correlated with chlorophyll a in February 1990, but not in May 1989, when a marked deep chlorophyll maximum was present. Significant positive correlations between RNA concentration and primary production and between RNA: DNA and primary production were found during both surveys, probably reflecting both higher RNA concentrations per cell and enhanced bacterial and microheterotrophic growth in high primary production situations. The results support the potential usefulness, in biological oceanography, of biochemical indicators based on DNA and RNA concentrations.
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Estrada M., C. Marrasé, M. Latasa, E. Berdalet, M. Delgado, T. Riera
Marine Ecology Progress Series, 92, 289-300. (BibTeX: estrada.etal.1993)
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Markager S., A.M. Jespersen, T.V Madsen, E. Berdalet, R. Weisburd
Hydrobiologia, 238, 1, 119-130.. DOI: 10.1007/BF00048780 (BibTeX: markager.etal.1992)
Resum: Veure
The dark respiration of a natural plankton community from an eutrophic lake was studied in a laboratory scale enclosure (LSE), exposed to illumination which simulated natural light conditions in the water column. The dark respiration was measured continuously for 2 hours in samples obtained from the LSE each hour for 26 hours. The relationships between dark respiration rates, carbohydrate concentrations and other parameters were investigated. The dark respiration rate showed an exponential decrease with time in the dark in all light period incubations with a time coefficient of 0.3 h–1. The decrease in respiration rate in the dark period was much slower, reaching an approximately constant level at the end of the night. The overall dark period decline in respiration rate also exhibited an exponential pattern, but with a much lower time coefficient (0.04 h –1) than for the light period incubations. A linear relationship was found between dark respiration rate and carbohydrate concentration at night time but no relationship was apparent during the day. A comparison between these data and data from the literature show that this pattern of dark respiration rate decrease with time in the dark may have some general applications for dense phytoplankton communities.
Paraules clau: phytoplankton - respiration - diel changes - carbohydrate
Berdalet E.,
Journal of Phycology, 28, 3, 267-272. DOI: 10.1111/j.0022-3646.1992.00267.x (BibTeX: berdalet.1992)
Resum: Veure
Laboratory experiments were conducted to study the effects of agitation on growth, cell division, and nucleic acid dynamics of the dinoflagellate Gymnodinium nelsonii Martin. When cultures were placed on an orbital shaker at 100 rpm, cell division was prevented, cellular volume increased up to 1.5 times that of the nonperturbed cells, the form and location of the cell nucleus were modified, and the RNA and DNA concentrations per cell increased up to 10 times those of the controls. When shaking was stopped after 10 days, cells divided immediately at about 2/3 of the division rate of the unshaken populations, and all the altered parameters were restored. If the agitation continued for more than 20 days, total cell death and disintegration occurred. Several cellular types differing in size and shape were observed in the control and shaken cultures. One possible hypothesis for these results is that failure of the cell to divide results from physical disturbance of the microtubule assemblage associated with chromosome separation during mitosis. My study suggests that small-scale oceanic turbulence of sufficient intensity may inhibit growth of individual dinoflagellate cells, but immediate development of the population may continue when calm weather follows the active mixing period.
Paraules clau: cell division; dinoflagellates; DNA; Gymnodinium nelsonii; Pyrrophyta; RNA; turbulence
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Kromkamp J., F. Schanz, M. Rijkeboer, E. Berdalet, B. Kim, H.J. Gons
Hydrobiologia, 238, 1, 111-118. DOI: 10.1007/BF00048779 (BibTeX: kromkamp.etal.1992)
Resum: Veure
The photosynthesis of plankton sampled from the eutrophic Lake Loosdrecht was studied in Laboratory Scale Enclosures (LSEs) with regard to the rate of mixing. First, two LSEs were operated at different mixing rates. No significant differences in photosynthetic performance were found, with the exception of a depressed photosynthesis in the afternoon in the LSE which had a low mixing rate. Secondly, when mixing was stopped, the phytoplankton which stayed in the dark due to the steep light gradient in the LSE responded by changing its maximal photosynthetic capacity. The results show that the filamentous cyanobacteria in the lake can respond rapidly to changes in the depth of the mixed layer by altering their photosynthetic performance.
Paraules clau: mixing regime - Laboratory Scale Enclosures - phytoplankton - photosynthesis
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Berdalet E., M. Latasa, M. Estrada
Hydrobiologia, 238, 1, 139-147. DOI: 10.1007/BF00048782 (BibTeX: berdalet.etal.1992)
Resum: Veure
The division cycle of two phytoplankton species, Olisthodiscus luteus and Heterocapsa sp. was studied in relation to a 12:12 light:dark cycle. Batch cultures in exponential phase were sampled every three hours during 48 hours. Cell number, cellular volume and DNA and RNA concentrations were measured. Microscopic observations of the nuclei of Heterocapsa sp. were also performed. In both species, cell division took place in the dark. In Heterocapsa sp., DNA and RNA showed a similar diel variability pattern, with synthesis starting at the end of the light period, previously to mitosis and cytokinesis. In O. luteus. Major RNA synthesis occurred during darkness, and DNA was produced almost continuously. Both species presented different values and diel rhythmicity on the RNA/DNA ratios.
Paraules clau: Heterocapsa - Olisthodiscus - RNA/DNA - cell cycle
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Latasa M., E. Berdalet, M. Estrada
Hydrobiologia, 238, 1, 149-157. DOI: 10.1007/BF00048783 (BibTeX: latasa.etal.1992)
Resum: Veure
Photosynthetic pigment composition was studied in batch cultures of Heterocapsa sp. and Olisthodiscus luteus growing exponentially in a 12:12 light:dark cycle. Both species divided in the dark. The synthesis of pigments was continuous for both species. However for chlorophyll c and peridinin, in Heterocapsa sp., and chlorophyll c and fucoxanthin, in O. luteus, (pigments belonging to light harvesting complexes) the synthesis was significantly higher during the light period. Concentrations per total cell volume (TCV) of chlorophyll a, chlorophyll c, peridinin and diadinoxanthin in Heterocapsa sp., and chlorophyll a, chlorophyll c, fucoxanthin and violaxanthin in O. luteus, showed a maximum at the onset of light and decreased during the light period. The values of the chlorophyll a:chlorophyll c, chlorophyll a:peridinin and chlorophyll a:fucoxanthin ratios are compared with data reported in the literature.
Paraules clau: Heterocapsa sp.; Olisthodiscus luteus - cycles - pigments - HPLC
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Berdalet Andrés E.,
PhD thesis. Director/es: M. Estrada i Miyares. Barcelona. (BibTeX: berdaletandres.1991b)
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Varela R., Grupo FRONTS (S. Agustí, P. Andreu, M. Alcaraz, J. Arístegui, E. Berdalet, J. Calderón, C. Castellón, A. Cruzado, M. Delgado, M. Estrada, X. Fusté, J. Gabarrou, M. Latasa, M. Manriquez, C. Marrasé, N. Martínez, R. Martínez, M. Masó, R. Massana, M. Palau, I. Palomera, T. Riera, V. Rodríguez, J. Ruíz, E. Saiz, J. Salat, J. Sanchez-Pardo
ISSN: 0210-0827 (BibTeX: varela.etal.1991h)
Resum: Veure
Las campañas FRONTS 1989,1990,1991 se desarrollaron dentro del marco del Proyecto FRONTS. Estudio de los efectos hidrodinámicos sobre la distribución y fisiología de las comunidades planctónicas en los frentes del Mar Catalán, subvencionado por la CYCYT (No.MAR88-0252). En particular, se trataba de analizar los efectos de inestabilidades intermitentes de mesoescala sobre la distribución del fitoplancton en un sistema frontal, y la influencia del frente costero catalán sobre la distribución espacio-temporal de las comunidades del zooplancton.
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Berdalet E., Q. Dortch
Marine Ecology Progress Series, 73, 295-305. DOI: 10.3354/meps073295 (BibTeX: berdalet.dortch.1991a)
Resum: Veure
The use of RNA: DNA ratios as a biochemical indicator is hampered by the lack of simple and reliable methods for routine work. The technique presented here approaches this problem by using 2 fluorochromes: Hoechst 33258, which specifically reacts ~ l t hDN A, and Thiazole Orange, which allows total nucleic acid estimation. Samples dre honlogenized in ~ris-Ca'+ buffer which is also used in the fluorometric analysis. Subsequently, these fluorochromes are added to different subsamples of the same nucleic arid extract. Several extraction and analysis techniques were tested and an optimized procedure is described The technique 1s simple and more sensitive than previously described methods for the determination of RNA and DNA In phytoplankton.
Andreu P., C. Marrase, E. Berdalet
Journal of Plankton Research, 11, 2, 185-192. DOI: 10.1093/plankt/11.2.185 (BibTeX: andreu.etal.1989)
Resum: Veure
Chaetognaths were identified and counted in 23 samples collected in the west Indian Ocean along a transect from the Gulf of Aden to the Cape of Good Hope, in February–March 1967. Although the hydrographic front located at 5°S does not seem to represent a barrier for the distribution of the majority of the species, some of them are in a preferential area south or north of the front. The principal component analysis indicates the locations where the more intense overlapping of species takes place. It is important to mention the occurrence of S.pseudoserratodentata in the proximity of Madagascar Island.
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Masó M., Grup PEPS (M. Alcaráz, P. Algarra, E. Berdalet, G. Ganzani, E. Carr, A. Castellón, A. Cruz, A. Cruzado, M. Delgado, O. Delgado, M. Estrada, S. Ferrer, J. Flos, J.M. Fortuño, X. Fusté, S. Mallo, M. Manríquez, R. Margalef, X. Modamio, T.T. Packard, M. Pagespetit, R. Ras, T. Riera, E. Saiz, J. Salat, F. Vallespinós, D. Vaqué, M. Zabala)
ISSN: 0210-0827 (BibTeX: maso.etal.1988e)
Resum: Veure
Todas las campañas se realizaron a bordo del B/O "García del Cid". Las tres campañas FRONTS (3-85, 6-85,11 -86) formaban parte del proyecto "Contribución de frentes hidrográficos costeros a la producción estival en el mar Catalán-Balear" (financiado por el CSIC y la ayuda nº PR84-0067 de la Comisión Asesora de Investigación Científica y Técnica). Las campañas PEP-86 y PEP-87 eran parte del proyecto "El máximo profundo de clorofila" (financiado por el CSIC y el Comité Conjunto Hispano-Norteamericano de cooperación Científica y Técnica, ayuda nº CCA8411054). Las fechas de las campañas se dan en la tabla 1 y las estaciones visitadas se muestran en las figuras 1 a 6. El presente volumen de Datos Informativos recoge los datos básicos obtenidos.