Articles de revues : « Planktonic ecosystem »

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Beaugrand, Grégory. « Monitoring pelagic ecosystems using plankton indicators ». ICES Journal of Marine Science 62, n^o 3 (1 janvier 2005) : 333–38. http://dx.doi.org/10.1016/j.icesjms.2005.01.002.

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Abstract Planktonic organisms are an important food resource of pelagic ecosystems, but they also serve as an integrator of hydroclimatic forcing. Four types of recently developed plankton indicator, based on the Continuous Plankton Recorder survey, are summarized here: indicators based on individual taxa; indicators based on functional attributes of the ecosystem (diversity); species assemblage indicators; and indicators of larval fish survival. All provide information on the state of a pelagic ecosystem, but have different limitations. Therefore, their combined application provides the most accurate diagnosis of ecosystem state. In most of the examples described, statistical analyses help to identify major spatial and temporal patterns, and may allow future ecosystem changes to be anticipated.

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Zhang, Meijing, Ruitong Jiang, Jianlin Zhang, Kejun Li, Jianheng Zhang, Liu Shao, Wenhui He et Peimin He. « The Impact of IMTA on the Spatial and Temporal Distribution of the Surface Planktonic Bacteria Community in the Surrounding Sea Area of Xiasanhengshan Island of the East China Sea ». Journal of Marine Science and Engineering 11, n^o 3 (23 février 2023) : 476. http://dx.doi.org/10.3390/jmse11030476.

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The growing world population has produced an increasing demand for seafood, and the aquaculture industry is under corresponding pressure to fill this demand. The offshore ecology and environment are under significant threat with the continuous expansion of the scale and intensity of aquaculture. Integrated multi-tropic aquaculture (IMTA) is a healthy and sustainable mariculture model based on ecosystem-level management, and has become popular in recent years. It is an effective way to cope with the significant changes in offshore ecosystems under multiple stressors. Phytoplankton bacteria are essential to maintaining the marine ecosystem’s balance and stability. Investigating the changes in the community structure of marine planktonic bacteria can elucidate the impact of mariculture on the marine ecological environment. This study took the fish-shell IMTA system with natural macroalgae nearby as the object, and monitored the plankton community’s structure in the system’s surface seawater for four quarters from July 2020 to April 2021. The space–time distribution characteristics and influencing factors of the plankton community in the surface water were examined. The results showed no significant difference between the planktonic bacterial communities at different sampling sites. There was also no significant difference in the α-diversity index. However, the dominant species and abundance of planktonic bacteria at the sampling sites differed significantly. Proteobacteria and Bacteroides were the dominant groups of planktonic bacteria. The results of the distance-based redundancy analysis demonstrated that chemical oxygen demand, chlorophyll a, and dissolved oxygen constituted the primary environmental factors affecting the planktonic bacterial community structures. The heatmap also showed that NH4+- N, temperature, and salinity levels were also related to certain planktonic bacteria. This study preliminarily identified the distribution of the surface bacterial plankton community and its response to changes in environmental factors in the sea area near Xiasanhengshan Island. The results provide a preliminary basis for assessing the health and stability of the IMTA system in open sea areas.

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D’Alelio, Domenico, Luca Russo, Gabriele Del Gaizo et Luigi Caputi. « Plankton under Pressure : How Water Conditions Alter the Phytoplankton–Zooplankton Link in Coastal Lagoons ». Water 14, n^o 6 (19 mars 2022) : 974. http://dx.doi.org/10.3390/w14060974.

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Transitional waters (TWs), such as coastal lagoons, are bodies of surface water at the transition between saline and freshwater domains. These environments play a vital role in guaranteeing ecosystem services, including provision of food, protection against meteorological events, as anthropogenic carbon sinks, and in filtering of pollutants. Due to the escalating overpopulation characterising coastlines worldwide, transitional systems are over-exploited, degraded, and reduced in their macroscopic features. However, information on the impact of anthropogenic pressures on planktonic organisms in these systems is still scanty and fragmented. Herein, we summarise the literature, with a special focus on coastal lagoons undergoing anthropogenic pressure. Specifically, we report on the implications of human impacts on the ecological state of plankton, i.e., a fundamental ecological component of aquatic ecosystems. Literature information indicates that human forces may alter ecosystem structures and functions in coastal lagoons, as in other TWs such as estuaries, hampering the phytoplankton–zooplankton link, i.e., the main trophic process occurring in those communities, and which sustains aquatic productivity. Changes in the dominance and lifestyle of key planktonic players, plus the invasion of ‘alien’ species, and consequent regime shifts, are among the most common outcomes of human disturbance.

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Schartau, Markus, Philip Wallhead, John Hemmings, Ulrike Löptien, Iris Kriest, Shubham Krishna, Ben A. Ward, Thomas Slawig et Andreas Oschlies. « Reviews and syntheses : parameter identification in marine planktonic ecosystem modelling ». Biogeosciences 14, n^o 6 (29 mars 2017) : 1647–701. http://dx.doi.org/10.5194/bg-14-1647-2017.

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Abstract. To describe the underlying processes involved in oceanic plankton dynamics is crucial for the determination of energy and mass flux through an ecosystem and for the estimation of biogeochemical element cycling. Many planktonic ecosystem models were developed to resolve major processes so that flux estimates can be derived from numerical simulations. These results depend on the type and number of parameterizations incorporated as model equations. Furthermore, the values assigned to respective parameters specify a model's solution. Representative model results are those that can explain data; therefore, data assimilation methods are utilized to yield optimal estimates of parameter values while fitting model results to match data. Central difficulties are (1) planktonic ecosystem models are imperfect and (2) data are often too sparse to constrain all model parameters. In this review we explore how problems in parameter identification are approached in marine planktonic ecosystem modelling. We provide background information about model uncertainties and estimation methods, and how these are considered for assessing misfits between observations and model results. We explain differences in evaluating uncertainties in parameter estimation, thereby also discussing issues of parameter identifiability. Aspects of model complexity are addressed and we describe how results from cross-validation studies provide much insight in this respect. Moreover, approaches are discussed that consider time- and space-dependent parameter values. We further discuss the use of dynamical/statistical emulator approaches, and we elucidate issues of parameter identification in global biogeochemical models. Our review discloses many facets of parameter identification, as we found many commonalities between the objectives of different approaches, but scientific insight differed between studies. To learn more from results of planktonic ecosystem models we recommend finding a good balance in the level of sophistication between mechanistic modelling and statistical data assimilation treatment for parameter estimation.

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Healey, Katherine, Adam H. Monahan et Debby Ianson. « Perturbation dynamics of a planktonic ecosystem ». Journal of Marine Research 67, n^o 5 (1 septembre 2009) : 637–66. http://dx.doi.org/10.1357/002224009791218841.

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Anufriieva, Elena, Elena Kolesnikova, Tatiana Revkova, Alexander Latushkin et Nickolai Shadrin. « Human-Induced Sharp Salinity Changes in the World’s Largest Hypersaline Lagoon Bay Sivash (Crimea) and Their Effects on the Ecosystem ». Water 14, n^o 3 (28 janvier 2022) : 403. http://dx.doi.org/10.3390/w14030403.

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Lakes and lagoons play an important role worldwide, and salinity fluctuations significantly affect their ecosystems. Bay Sivash, the world’s largest hypersaline water body, underwent a sharp change in salinity, induced by the closing of the North Crimean Canal. To monitor a shift in the ecosystem, a study was carried out from 2014 to 2020 at 15 sites of the lagoon. Since the closure of the canal, the average salinity increased from 22 g L−1 (2013) to 94 g L−1 (2020). Suspended solids and dissolved organic matter also increased. When salinity increased above 50 g L−1, the number of taxa significantly decreased; this was a negative linear relation. The increase in salinity significantly changed the structure of zooplankton and benthos. The most dramatic changes occurred with the salinity increase from 25 to 70 g L−1. Chironomidae larvae numbers began to increase greatly in the ecosystem of the bay, and since 2014, they have rapidly increased their contribution to the abundance of benthos and plankton. The concentration of benthic–planktonic species increased in plankton, in particular, in Harpacticoida and Chironomidae. At salinity above 80–90 g L−1, nauplii and adult brine shrimp appeared to become abundant in plankton and benthos. The transit of the ecosystem to a new alternative state occurred.

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Grigoratou, Maria, Fanny M. Monteiro, Daniela N. Schmidt, Jamie D. Wilson, Ben A. Ward et Andy Ridgwell. « A trait-based modelling approach to planktonic foraminifera ecology ». Biogeosciences 16, n^o 7 (10 avril 2019) : 1469–92. http://dx.doi.org/10.5194/bg-16-1469-2019.

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Abstract. Despite the important role of planktonic foraminifera in regulating the ocean carbonate production and their unrivalled value in reconstructing paleoenvironments, our knowledge on their ecology is limited. A variety of observational techniques such as plankton tows, sediment traps and experiments have contributed to our understanding of foraminifera ecology. But, fundamental questions around costs and benefits of calcification and the effect of nutrients, temperature and ecosystem structure on these organisms remain unanswered. To tackle these questions, we take a novel mechanistic approach to study planktonic foraminifera ecology based on trait theory. We develop a zero-dimensional (0-D) trait-based model to account for the biomass of prolocular (20 µm) and adult (160 µm) stages of non-spinose foraminifera species and investigate their potential interactions with phytoplankton and other zooplankton under different temperature and nutrient regimes. Building on the costs and benefits of calcification, we model two ecosystem structures to explore the effect of resource competition and temperature on planktonic foraminifera biomass. By constraining the model results with ocean biomass estimations of planktonic foraminifera, we estimate that the energetic cost of calcification could be about 10 %–50 % and 10 %–40 % for prolocular and adult stages respectively. Our result suggest that the shell provides protection against processes other than predation (e.g. pathogen invasion). We propose that the low standing biomass of planktonic foraminifera plays a key role in their survival from predation, along with their shell protection. Our model suggests a shift from temperature as a main regulator of foraminifera biomass in the early developmental stage to resource competition for adult biomass.

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Bueno, Marília, Samantha Fernandes Alberto, Renan de Carvalho, Tânia Marcia Costa, Áurea Maria Ciotti et Ronaldo Adriano Christofoletti. « Plankton in waters adjacent to the Laje de Santos state marine conservation park, Brazil : spatio-temporal distribution surveys ». Brazilian Journal of Oceanography 65, n^o 4 (décembre 2017) : 564–75. http://dx.doi.org/10.1590/s1679-87592017129006504.

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Abstract The coastal marine plankton plays a major role in ecosystem functioning by linking pelagic and benthonic environments through energy fluxes. Understanding the dynamic of planktonic organisms is also crucial for conservation and management purposes. Plankton was sampled at ten sites in the waters of the PEMLS and the adjacent area, on four different occasions through 2013 and 2015 in order to identify key planktonic groups and protocols for long-term monitoring. Ninety taxa of zooplanktonic organisms were found with holoplanktonic copepods and cladocerans dominating samples. Zooplankton biomass, mortality and taxonomic composition varied both in space and time. Surface chlorophyll-a concentrations varied spatio-temporally. A protocol for monitoring the plankton of the waters in and adjacent to the PEMLS is suggested based on biomass and mortality of zooplankton and biomass of phytoplankton using periodically in situ calibrated ocean color satellite imagery.

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Anderson, T. R., W. C. Gentleman et A. Yool. « EMPOWER-1.0 : an Efficient Model of Planktonic ecOsystems WrittEn in R ». Geoscientific Model Development 8, n^o 7 (24 juillet 2015) : 2231–62. http://dx.doi.org/10.5194/gmd-8-2231-2015.

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Abstract. Modelling marine ecosystems requires insight and judgement when it comes to deciding upon appropriate model structure, equations and parameterisation. Many processes are relatively poorly understood and tough decisions must be made as to how to mathematically simplify the real world. Here, we present an efficient plankton modelling testbed, EMPOWER-1.0 (Efficient Model of Planktonic ecOsystems WrittEn in R), coded in the freely available language R. The testbed uses simple two-layer "slab" physics whereby a seasonally varying mixed layer which contains the planktonic marine ecosystem is positioned above a deep layer that contains only nutrient. As such, EMPOWER-1.0 provides a readily available and easy to use tool for evaluating model structure, formulations and parameterisation. The code is transparent and modular such that modifications and changes to model formulation are easily implemented allowing users to investigate and familiarise themselves with the inner workings of their models. It can be used either for preliminary model testing to set the stage for further work, e.g. coupling the ecosystem model to 1-D or 3-D physics, or for undertaking front line research in its own right. EMPOWER-1.0 also serves as an ideal teaching tool. In order to demonstrate the utility of EMPOWER-1.0, we implemented a simple nutrient–phytoplankton–zooplankton–detritus (NPZD) ecosystem model and carried out both a parameter tuning exercise and structural sensitivity analysis. Parameter tuning was demonstrated for four contrasting ocean sites, focusing on station BIOTRANS in the North Atlantic (47° N, 20° W), highlighting both the utility of undertaking a planned sensitivity analysis for this purpose, yet also the subjectivity which nevertheless surrounds the choice of which parameters to tune. Structural sensitivity tests were then performed comparing different equations for calculating daily depth-integrated photosynthesis, as well as mortality terms for both phytoplankton and zooplankton. Regarding the calculation of daily photosynthesis, for example, results indicated that the model was relatively insensitive to the choice of photosynthesis–irradiance curve, but markedly sensitive to the method of calculating light attenuation in the water column. The work highlights the utility of EMPOWER-1.0 as a means of comprehending, diagnosing and formulating equations for the dynamics of marine ecosystems.

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Shyam, Radhey, Pramod Kumar et Smita Badola. « Seasonal variation in the planktonic diversity of Tumaria reservoir of Kashipur Uttarakhand India ». Environment Conservation Journal 21, n^o 3 (11 décembre 2020) : 119–25. http://dx.doi.org/10.36953/ecj.2020.21314.

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Plankton are the microscopic plants and animals found in any aquatic ecosystem. Phytoplankton are microscopic plants while zooplankton are microscopic animals. The present investigation was carried out to find out the planktonic diversity of the Tumaria reservoir during January-December 2018. To fulfill the objectives of the present study, samples were collected from Tumaria reservoir on monthly basis. The samples were analysed for various physicochemical parameters (temperature, transparency, TDS, TS, pH, DO and chloride) and planktonic diversity. During the present study phytoplankton and zooplankton were identified under the microscope with the help of standard photographs following standard reference materials. During course of study phytoplankton was observed were Chlorophyceae (50%) > Bacillariophyceae (37%) > Cyanophyceae (13%) while zooplankton observed were Rotifera (40%) > Protozoa (34%) > Cladocera (23%) > Copepod (3%). It was also found that plankton diversity was found higher during the winter months followed by summer and minimum during the monsoon months. Planktonic diversity observed during study was found strongly correlated with temp (r= -0.56) and transparency (r=0.95).

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Belmonte, Genuario, et Fernando Rubino. « POTENTIAL AND REALIZED DIVERSITY OF COASTAL PLANKTON : THE ROLE OF RESTING STAGES IN ECOSYSTEM FUNCTIONING ». Arquivos de Ciências do Mar 55, Especial (21 mars 2022) : 477–84. http://dx.doi.org/10.32360/acmar.v55iespecial.78207.

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Resting stages are the strategy for species to avoid the variability of environmental conditions. In coastal confined marine habitats, variability of conditions is higher than in the open sea, and bottoms accumulate plankton resting stages in the so-called “marine cyst banks”. The benthic-pelagic coupling generated by this bi-location of plankton, however, is not clearly evident for all the involved species. This result is due to the still scant knowledge of the life cycles and life histories of single species. The study of plankton dynamics from the benthos point of view is useful and informative and it increases the potential complexity of a planktonic community in a confined area. Keywords: plankton, life cycles, resting stages, cysts, benthic-pelagic coupling, resurrection ecology.

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Vaghela, Krishnakumar B., Devangee P. Shukla et Nayan K. Jain. « A Study of Phytoplankton and Zooplankton Diversity in the River Sabarmati, Gujarat, India ». Asian Journal of Environment & ; Ecology 22, n^o 4 (15 novembre 2023) : 28–38. http://dx.doi.org/10.9734/ajee/2023/v22i4505.

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Abiotic and biotic components are divided into two categories to describe the structural ecosystem. Aquatic plants and animals can find a suitable habitat in the river's water body. Planktons are an important component of the wetland ecology and may serve as a marker of altering water quality. Zooplankton mostly obtains its nutrition from phytoplankton, an ecosystem producer. Most fish larvae and other plankton-eating fishes feed primarily on zooplankton species. All aquatic ecosystems' dynamics revolve around primary productivity, which sustains various food chains and food webs. The overgrowth of macrophytes, pesticides from agricultural runoff, household garbage, sewage sludge, feces near rivers, bathing of domestic animals, washing of clothing and utensils, etc. have all put pressure on river ecosystems over the past many years. Most plants and animals struggle to survive in polluted environments, but those that can handle the stress of pollution on their own may be able to. These creatures can serve as pollution indicators, or more particularly, as bioindicators of the ecosystem's trophic condition. In this article, Sabarmati River's phytoplankton and zooplankton communities were evaluated at six different locations. The current investigations were researched from January 2017 to December 2019 over a period of around 3 years. Several published plankton manuals were used for plankton collection and identification. Aquatic flora analyzed here in two respects i.e., phytoplankton and aquatic vegetation or aquatic weeds. Phytoplankton were represented by four groups, viz. Bacilariophyceae, Chlorophyceae, Cyanophyceae, and Euglenophyceae. Diversity study reveals common planktonic forms present at different sites of sampling. In general, aquatic weeds like Hydrilla, Valesneria, Chara, Nymphea, Pistia, Typha etc. were commonly found in the study area. Protozoa, Cladocera, Copepoda and Rotifers are the main groups of zooplankton found in freshwater bodies. Six Molluscans and sixteen Arthropods were identified to be the most commonly occurring riparian fauna. The annual values of all zooplankton showed greater densities at site-1 and site-6 followed by other sites, respectively. When the data were analyzed for contribution of each phylum to the overall zooplankton densities, it was dominated by Protozoa and Arthropods throughout the study period. This was followed by Rotifera, Annelid and Nematoda, respectively. The percentile composition of protozoan fauna at six study sites suggested that on more than half of the sampling occasions their major contribution was recorded at sites 1, 2 and 6 followed by sites 5, 4 and 3, respectively.

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Woods, John. « Understanding the ecology of plankton ». European Review 7, n^o 3 (juillet 1999) : 371–84. http://dx.doi.org/10.1017/s1062798700004154.

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Plankton are microscopic organisms living in the sea. They are responsible for more than half of the biological production of our planet. They also influence global climate, fisheries and pollution. Understanding the ever-changing distribution of plankton in the ocean is one of the grand challenges of science. The scope of the problem has been well documented in the 20th century, and new research tools should greatly accelerate progress in the 21st century. A particularly promising tool is mathematical simulation of the ecosystem, in which the demographics of plankton populations are derived from the growth and behaviour of individual organisms, each responding to its immediate environment. These use new computer codes, based on the Lagrangian Ensemble method, which are at the leading edge of complexity simulation. When integrated on massively parallel computers they can simulate the individual histories of millions of plankters for several decades. These ‘virtual plankton ecosystems’ help us to understand the complex processes responsible for the ever-changing patterns of planktonic life in the ocean.

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Peters, F. « On some relationships between storms and plankton dynamics ». Advances in Geosciences 26 (30 juin 2010) : 33–38. http://dx.doi.org/10.5194/adgeo-26-33-2010.

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Abstract. The physico-chemical fields of the pelagic environment are constantly fluctuating at different spatial and temporal scales. Storms are extreme events of such fluctuations that cascade down to small scales to alter nutrient availability to microscopic algae or swimming and mating behaviour of motile plankton. Mediterranean storms sometimes are also responsible for the transport of micro and macronutrients from Saharan origin, albeit the significance for marine production is still under question. In coastal ecosystems, storms represent dissolved nutrient injections via run-off and resuspension that trigger planktonic succession events. Storms may also have a role in the development and mitigation of harmful algal blooms, events with economic and health consequences that are of growing societal concern. Based on laboratory experiments on the effects of turbulence on swimming behaviour and population growth of dinoflagellates, a conceptual sequence of events is proposed for bloom initiation. Overall, storms affect, directly or indirectly, the dynamics of plankton and hence ecosystem production and cannot be considered catastrophic or hazardous in this context. The full potential of such relationships will be evidenced once biological time series match the resolution and spatial coverage of meteorological and oceanic data. As the frequency and intensity of storms is subject to global change, future oceanic ecosystem production should be affected as well.

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MOHAN, Bala, Sheela PRIYADARSHINEE, Ramaswamy KALPANA et Periyakali Saravana BHAVAN. « IMPACT OF SEASONAL CHANGES IN FRESHWATER PHYTOPLANKTON AND ZOOPLANKTON BIODIVERSITY AT VALANKULAM LAKE, COIMBATORE DISTRICT, TAMIL NADU, INDIA ». Journal of Applied Life Sciences and Environment 55, n^o 3 (191) (27 février 2023) : 271–92. http://dx.doi.org/10.46909/alse-552063.

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The plankton communities are important source of food for the aquatic organisms, and if any undesirable changes in aquatic environment may affect plankton diversity and density. Therefore, assessment of planktonic communities in the freshwater ecosystems is essential because they serve as bio-indicators of water quality parameters. Hence, the present research was focused to evaluate the freshwater phytoplankton and zooplankton diversity and their abundance in Valankulam Lake (Lat. 10.59° N and Long. 76.57° E), at Coimbatore city, Tamil Nadu, India. Results from the study revealed that a total of 77 species of phytoplankton and zooplankton were recorded, under 37 families and 46 genera. In addition to that, a total of 43 phytoplankton species were recorded under 25 families and 30 genera, (which includes; 15 species of Cyanophyceae, 17 species of Chlorophyceae, 08 species of Bacillariophyceae, 03 species of Euglenophyceae). and a total of 34 species of zooplankton were recorded under 12 families and 17 genera, (which includes 13 species of Rotifera, 09 species of Cladocera, 08 species of Copepoda and 04 species of Ostracoda). The maximum plankton diversity was observed during the monsoon season and the minimum in the summer season. Results from study revealed the ecological status of the lake is categorized as moderately polluted due to the presence of municipal waste and industrial discharges into the lake water. Therefore, the assessment of planktonic communities in water bodies will be useful to monitor and maintain the water quality parameters and wealth of aquatic biota in the aquatic ecosystem.

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Axler, KE, S. Sponaugle, C. Briseño-Avena, F. Hernandez, SJ Warner, B. Dzwonkowski, SL Dykstra et RK Cowen. « Fine-scale larval fish distributions and predator-prey dynamics in a coastal river-dominated ecosystem ». Marine Ecology Progress Series 650 (17 septembre 2020) : 37–61. http://dx.doi.org/10.3354/meps13397.

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River plumes discharging into continental shelf waters have the potential to influence the distributions, predator-prey relationships, and thus survival of nearshore marine fish larvae, but few studies have been able to characterize the plume environment at sufficiently fine scales to resolve the underlying mechanisms. We used a high-resolution plankton imaging system and a sparse convolutional neural network to automate image classification of larval fishes, their planktonic prey (calanoid copepods), and gelatinous planktonic predators (ctenophores, hydromedusae, and siphonophores) over broad spatial scales (km) and multiple pulses of estuarine water exiting Mobile Bay (Alabama, USA) into the northern Gulf of Mexico from 9-11 April 2016. Fine-scale (1 m) plankton distributions were examined to analyze predator-prey relationships across 3 distinct plume regimes that varied by degree of wind-forcing and mixing rates. In calm wind conditions, the water column was highly stratified, and fish larvae and zooplankton were observed aggregating in a region of river plume-derived hydrodynamic convergence. As winds strengthened, the water column was subjected to downwelling and highly turbulent conditions, and there was decreasing spatial overlap between larval fishes and their zooplankton prey and predators. Our results indicate that high-discharge plume regimes characterized by strong wind-forcing and turbulence can rapidly shift the physical and trophic environments from favorable to unfavorable for fish larvae. Multiple pathways for both nearshore retention and advective dispersal of fish larvae were also identified. Documenting this variability is a first step toward understanding how high discharge events and physical forcing can affect fisheries production in river-dominated coastal ecosystems worldwide.

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De Laender, F., K. A. C. De Schamphelaere, C. R. Janssen et P. A. Vanrolleghem. « An ecosystem modelling approach for deriving water quality criteria ». Water Science and Technology 56, n^o 6 (1 septembre 2007) : 19–27. http://dx.doi.org/10.2166/wst.2007.582.

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Ecological effects of chemicals on ecosystems are the result of direct effects of the chemical, determined in single-species toxicity testing, and indirect effects due to ecological interactions between species. Current experimental methods to account for such interactions are expensive. Hence, mathematical models of ecosystems have been proposed as an alternative. The use of these models often requires extensive calibration, which hampers their use as a general tool in ecological effect assessments. Here we present a novel ecosystem modelling approach which assesses effects of chemicals on ecosystems by integrating single-species toxicity test results and ecological interactions, without the need for calibration on case-specific data. The methodology is validated by comparing predicted ecological effects of copper in a freshwater planktonic ecosystem with an experimental ecosystem data set. Two main effects reflected by this data set (a decrease of cladocerans and an increase of small phytoplankton) which were unpredictable from single-species toxicity test results alone, were predicted accurately by the developed model. Effects on populations which don't interact directly with other populations, were predicted equally well by single-species toxicity test results as by the ecosystem model. The small amount of required data and the high predictive capacity can make this ecosystem modelling approach an efficient tool in water quality criteria derivation for chemicals.

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Li, Yan, Jiahong Guo, Xiaomin Guo, Zhiqiang Hu et Yu Tian. « Plankton Detection with Adversarial Learning and a Densely Connected Deep Learning Model for Class Imbalanced Distribution ». Journal of Marine Science and Engineering 9, n^o 6 (8 juin 2021) : 636. http://dx.doi.org/10.3390/jmse9060636.

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Detecting and classifying the plankton in situ to analyze the population diversity and abundance is fundamental for the understanding of marine planktonic ecosystem. However, the features of plankton are subtle, and the distribution of different plankton taxa is extremely imbalanced in the real marine environment, both of which limit the detection and classification performance of them while implementing the advanced recognition models, especially for the rare taxa. In this paper, a novel plankton detection strategy is proposed combining with a cycle-consistent adversarial network and a densely connected YOLOV3 model, which not only solves the class imbalanced distribution problem of plankton by augmenting data volume for the rare taxa but also reduces the loss of the features in the plankton detection neural network. The mAP of the proposed plankton detection strategy achieved 97.21% and 97.14%, respectively, under two experimental datasets with a difference in the number of rare taxa, which demonstrated the superior performance of plankton detection comparing with other state-of-the-art models. Especially for the rare taxa, the detection accuracy for each rare taxa is improved by about 4.02% on average under the two experimental datasets. Furthermore, the proposed strategy may have the potential to be deployed into an autonomous underwater vehicle for mobile plankton ecosystem observation.

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Soler T., E., J. G. Del Rio et J. J. Diez. « STUDY ON THE VARIATIONS OF AN EUTROPHIC ECOSYSTEM FROM THE SPANISH MEDITERRANEAN LITTORAL : DATA TO HAVE IN MIN IN THE NUTRIENT DUMPING TO THE SEA ». Coastal Engineering Proceedings 1, n^o 21 (29 janvier 1988) : 194. http://dx.doi.org/10.9753/icce.v21.194.

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Cullera Bay is a neritic ecosystem placed on the Spanish Mediterranean Littoral largely influenced by the Jucar River, that brings about lower salinities than surrounding waters, and broad variations of its values. An extensive research, with 9 samplings throughout the year, was carried out, measuring both physical and chemical parameters, and the planktonic communities. The trophic status of the ecosystem, the spatial and temporal variations of the nutrients and the planktonic communities were studied, evaluating the influence of the river loads and the littoral dynamics. Some essential basis to allow a suitable emplacement of waste waters disposals along the Valencian littoral are set up in order to minimize the gradual eutrophication of this coast.

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Talas, Liisi, Normunds Stivrins, Siim Veski, Leho Tedersoo et Veljo Kisand. « Sedimentary Ancient DNA (sedaDNA) Reveals Fungal Diversity and Environmental Drivers of Community Changes throughout the Holocene in the Present Boreal Lake Lielais Svētiņu (Eastern Latvia) ». Microorganisms 9, n^o 4 (31 mars 2021) : 719. http://dx.doi.org/10.3390/microorganisms9040719.

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Fungi are ecologically important in several ecosystem processes, yet their community composition, ecophysiological roles, and responses to changing environmental factors in historical sediments are rarely studied. Here we explored ancient fungal DNA from lake Lielais Svētiņu sediment throughout the Holocene (10.5 kyr) using the ITS metabarcoding approach. Our data revealed diverse fungal taxa and smooth community changes during most of the Holocene with rapid changes occurring in the last few millennia. More precisely, plankton parasitic fungi became more diverse from the Late Holocene (2–4 kyr) which could be related to a shift towards a cooler climate. The Latest Holocene (~2 kyr) showed a distinct increase in the richness of plankton parasites, mycorrhizal, and plant pathogenic fungi which can be associated with an increased transfer rate of plant material into the lake and blooms of planktonic organisms influenced by increased, yet moderate, human impact. Thus, major community shifts in plankton parasites and mycorrhizal fungi could be utilized as potential paleo-variables that accompany host-substrate dynamics. Our work demonstrates that fungal aDNA with predicted ecophysiology and host specificity can be employed to reconstruct both aquatic and surrounding terrestrial ecosystems and to estimate the influence of environmental change.

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Chaessman, BC. « Estimates of ecosystem metabolism in the La Trobe River, Victoria ». Marine and Freshwater Research 36, n^o 6 (1985) : 873. http://dx.doi.org/10.1071/mf9850873.

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Diel oxygen-curve techniques were used to estimate gross primary productivity (PG), community respiration and net daily metabolism (NDM) for five reaches of the La Trobe River from headwaters to lowlands. All reaches were heterotrophic throughout the study (December 1980-November 1981) with NDM ranging from - 1 to -6 g O2 m-2. PG was consistently very low at the most upstream station and highest in the middle reaches of the river, where both benthic and planktonic contributions were important. At the most downstream station benthic productivity was negligible but planktonic productivity was appreciable in spring and autumn. PG in the river may be limited in the upper reaches by lack of light (due to shading by vegetation) and low levels of nutrients, and in the lower reaches by turbidity and increased depth.

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AZZALI, IRENE, ANDREW MOROZOV et EZIO VENTURINO. « EXPLORING THE ROLE OF VERTICAL HETEROGENEITY IN THE STABILIZATION OF PLANKTONIC ECOSYSTEMS UNDER EUTROPHICATION ». Journal of Biological Systems 25, n^o 04 (décembre 2017) : 715–41. http://dx.doi.org/10.1142/s0218339017400034.

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Understanding plankton dynamics in marine and lake ecosystems under eutrophication is currently a hot topic in the literature. Simple theoretical models predict appearance of large amplitude oscillations of species densities in nutrient-rich waters; however, such predictions do not always correspond to field observations. Recent models taking into account heterogeneity of the growth rate of phytoplankton and active food-searching behavior of zooplankton demonstrated that grazers can efficiently control phytoplankton densities at low values even for a high nutrient stock. In this paper, we extend the previous modeling findings on the role of fast-moving plankton grazers by exploring a more realistic case where the limiting nutrient is a dynamical variable. Thus, the growth of phytoplankton across the water column depends on both light attenuation and dynamical depletion of nutrients. We also consider a more realistic scenario of a depth-dependent vertical turbulent diffusion. Most of the previous results on stabilization of planktonic ecosystems still hold; however, some alternative mechanisms of bloom suppression can also be possible. In particular, we demonstrate that the foraging of zooplankton according to the ideal free distribution (IFD) of food (which was previously considered to be a crucial condition for stabilization) may be less stabilizing than random foraging of zooplankton. We also show that stable top-down control in the ecosystem would be highly dependent on values of vertical diffusion and on the nutrient concentration in deep layers.

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Gaykar, B., A. Supate et L. Bhosale. « Productivity of Estuarine ecosystem ». Indian Journal of Forestry 29, n^o 1 (1 mars 2006) : 15–19. http://dx.doi.org/10.54207/bsmps1000-2006-r77m71.

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Estuarine ecosystem plays an important role in primary productivity. Phytoplanktons and mangroves show major contribution to balance ecosystem, on which many primary consumers are dependent. Primary productivity was investigated of three different estuaries, viz. Bhatye, Kalbadevi and Are as representatives of West Coast of Maharashtra. Productivity of phytoplankton was quantified via light-dark bottle experiments while mangrove productivity was measured by litterfall. Planktonic net primary productivity was high in the month of December- January (values ranged from 0.009 to 0.450 gC/m3/h). In Sonneratia alba maximum litter was contributed by fruits whereas in Rhizophora, it is the leaf which had major contribution. Though area under mangroves is comparatively less along West Coast, the ecosystem is vital and supports large variety of animal life.

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SINGH, TARKESHWAR, et PUNYASLOKE BHADURY. « Description of a new marine planktonic cyanobacterial species Synechococcus moorigangaii (Order Chroococcales) from Sundarbans mangrove ecosystem ». Phytotaxa 393, n^o 3 (22 février 2019) : 263. http://dx.doi.org/10.11646/phytotaxa.393.3.3.

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The genus Synechococcus is widespread across marine environments globally including in coastal habitats. In this study, culture of a new isolate (CMS01) of Synechococcus has been established and described based on polyphasic taxonomy from the world’s largest mangrove ecosystem, Sundarbans. This planktonic photoautrotroph has been proposed as a new species Synechococcus moorigangaii sp. nov. belonging to the order Chroococcales. The cells representing this proposed new species are solitary and can also form chain comprising of 4–6 cells. The shape of cell is oval to cylindrical and length ranges from 1.2–3 µm while the width ranges from 0.8–2 µm. The distribution pattern of photosynthetic filaments was found to be from the periphery of cell. Based on robust phylogeny of 16S rRNA, in addition to functional genes such as psbA, ureC, rbcL, and cbbA (multi gene phylogeny), the proposed new species differed from closest described species of Synechococcus under order Chroococcales. The fatty acid analysis indicated the presence of C12 and C14 chain fatty acids exclusive to isolate CMS01. The new isolate can grow across a range of salinity and in presence of different nitrogen sources. It has the ability to fix atmospheric di-nitrogen into ammonium ion. This new isolate of Synechococcus spp. is the first marine planktonic cyanobacterium described from a mangrove ecosystem and characterized using polyphasic approaches. Based on 16S rRNA phylogeny, this proposed new species clustered with Synechococcus strains PCC 7117, PCC 73109, PCC 7002, PCC 7003, PCC 7376 and NKNG15041c belonging to the order Chroococcales. The new species Synechococcus moorigangaii sp. nov. can serve as a model organism to understand ecophysiology and adaptation of planktonic cyanobacterial communities in mangrove ecosystems.

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Labonite, Eunice Kenee ,., et Beatriz Belonias. « Community Structure of Planktonic Algae in Pagpanganan River, Baybay City, Leyte ». Science and Humanities Journal 10, n^o 1 (1 décembre 2013) : 54–82. http://dx.doi.org/10.47773/shj.1998.101.4.

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Planktonic algae are free-floating phytoplankton that abound in aquatic and marine environments. They are the primary producers of aquatic ecosystems thus their role in the ecosystem cannot be overemphasized. This study was conducted in three sites of Pagbanganan River to determine the abundance and diversity of planktonic algae. A total of 39 genera under divisions Bacillariophyta, Chlorophyta, Cyanophyta and Charophyta were recorded. The most abuntat and dominant group were the diatoms (Divion Bacillariophyta). Navicula, Nitzschia, Synedra, Melosira and Coconies were the most abundant genera. The upstream, midstream and downstream sites were highly similar in phytoplankton composition and abundance. Phytoplankton were more abundant and dominant but less diverse during the months of April, May and June compared to July, August and September. Temperature, dissolved oxygen and nitrate levels were within safe limits but phosphate was in excess. Abundace was positively correlated with current velocity but negatively correlated with nitrate level.

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Berezina, Nadezhda A., Piotr M. Terentjev, Elena M. Zubova, Sergey M. Tsurikov, Alexey A. Maximov et Andrey N. Sharov. « Seasonal Diet Changes and Trophic Links of Cold-Water Fish (Coregonus albula) within a Northern Lake Ecosystem ». Animals 14, n^o 3 (25 janvier 2024) : 394. http://dx.doi.org/10.3390/ani14030394.

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The seasonal feeding patterns of the cold-adapted fish, Coregonus albula, are poorly studied in high-latitude lakes but could provide insight for predicting the effects of global warming. We examined vendace’s diet composition, traced the carbon and nitrogen isotope ratios from producers to consumers in the food web, and estimated vendace’s trophic position in a subarctic lake (the White Sea basin). Results showed the vendace to be a typical euryphagous fish, but clear seasonal differences were found in the relative importance of plankton and benthos in the diet. The vendace consumed primarily benthic amphipods in the summer, planktonic cladocerans in the autumn, and copepods in the winter–spring (under ice); larvae of aquatic insects were the second-most important food items throughout the year. Because of the substantial proportion of fish embryos in its diet, the vendace had a trophic position similar to that of a predatory fish (perch). The Bayesian food source-mixing model revealed that the majority of vendace energy derives from planktonic copepods. The dominant Cyclops had the lowest carbon isotope values, suggesting a carbon-depleted diet typical for methanotrophic bacteria, as its probable food source was in a lake under ice. Understanding the feeding patterns of vendace provides information to better predict the potential biotic effects of environmental change on lake ecosystems.

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Franks, P. J. S. « Planktonic ecosystem models : perplexing parameterizations and a failure to fail ». Journal of Plankton Research 31, n^o 11 (12 août 2009) : 1299–306. http://dx.doi.org/10.1093/plankt/fbp069.

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Heath, M. « Size spectrum dynamics and the planktonic ecosystem of Loch Linnhe ». ICES Journal of Marine Science 52, n^o 3-4 (août 1995) : 627–42. http://dx.doi.org/10.1016/1054-3139(95)80077-8.

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Andersen, Valérie, Paul Nival et Roger P. Harris. « Modelling of a planktonic ecosystem in an enclosed water column ». Journal of the Marine Biological Association of the United Kingdom 67, n^o 2 (mai 1987) : 407–30. http://dx.doi.org/10.1017/s0025315400026709.

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The analysis of the complex trophic relations characteristic of plankton communities is much simpler in an isolated body of water than in the open sea. In fact, in the open sea physical processes make many biological phenomena difficult to recognize, and advection and turbulence generally make it impossible to sample repetitively the same population of organisms for long periods of time.

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Wang, Qiang, et Mu Mu. « Responses of the ocean planktonic ecosystem to finite-amplitude perturbations ». Journal of Geophysical Research : Oceans 119, n^o 12 (décembre 2014) : 8454–71. http://dx.doi.org/10.1002/2014jc010339.

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Holmgren, Noel M. A., Niclas Norrström, Robert Aps et Sakari Kuikka. « MSY-orientated management of Baltic Sea herring (Clupea harengus) during different ecosystem regimes ». ICES Journal of Marine Science 69, n^o 2 (12 janvier 2012) : 257–66. http://dx.doi.org/10.1093/icesjms/fsr202.

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Abstract Holmgren, N. M. A., Norrström, N., Aps, R., and Kuikka, S. 2012. MSY-orientated management of Baltic Sea herring (Clupea harengus) during different ecosystem regimes. – ICES Journal of Marine Science, 69: 257–266. The Baltic Sea ecosystem has undergone dramatic changes, so-called ecosystem regime shifts, during the past four decades. Baltic Sea herring (Clupea harengus) spawning-stock biomass has declined to a third, and weight-at-age has halved as a result of food shortages and competition with sprat (Sprattus sprattus). The management objective for the herring stock is currently in transition from precautionary to maximum sustainable yield (MSY). The main basin Baltic Sea herring was modelled under the current ecosystem regime and the effect of a recovery of the cod (Gadus morhua) stock and the availability of planktonic food to levels found in the early 1980s analysed. A target of FMSY = 0.16 for herring, which should decline to FMSY = 0.10 with recovery of the cod stock, is proposed. An increase in the availability of planktonic food is estimated to more than double the yield at FMSY = 0.27, overriding the negative effects of cod predation should there be a simultaneous increase in both cod and availability of planktonic food. The estimated net increase in yield is 40% at FMSY = 0.20. Functions are presented to calculate FMSY and to estimate the expected yield depending on the abundance of cod and food availability. Retrospective application of the functions is indicative of overfishing of herring in the 1990s and early 2000s, and a net loss in yield, with a landing value of some €440 million.

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Fraile, I., M. Schulz, S. Mulitza et M. Kucera. « Predicting the global distribution of planktonic foraminifera using a dynamic ecosystem model ». Biogeosciences 5, n^o 3 (2 juin 2008) : 891–911. http://dx.doi.org/10.5194/bg-5-891-2008.

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Abstract. We present a new planktonic foraminifera model developed for the global ocean mixed-layer. The main purpose of the model is to explore the response of planktonic foraminifera to different boundary conditions in the geological past, and to quantify the seasonal bias in foraminifera-based paleoceanographic proxy records. This model is forced with hydrographic data and with biological information taken from an ecosystem model to predict monthly concentrations of the most common planktonic foraminifera species used in paleoceanography: N. pachyderma (sinistral and dextral varieties), G. bulloides, G. ruber (white variety) and G. sacculifer. The sensitivity of each species with respect to temperature (optimal temperature and range of tolerance) is derived from previous sediment-trap studies. Overall, the spatial distribution patterns of most of the species are in agreement with core-top data. N. pachyderma (sin.) is limited to polar regions, N. pachyderma (dex.) and G. bulloides are the most common species in high productivity zones, while G. ruber and G. sacculifer are more abundant in tropical and subtropical oligotrophic waters. For N. pachyderma (sin) and N. pachyderma (dex.), the season of maximum production coincides with that observed in sediment-trap records. Model and sediment-trap data for G. ruber and G. sacculifer show, in general, lower concentrations and less seasonal variability at all sites. A sensitivity experiment suggest that, within the temperature-tolerance range of a species, food availability may be the main parameter controlling its abundance.

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Bhalla, Resham, et Balwinder Sekhon. « Seasonal physico-chemical characteristics assessment and primary production in the planktonic community of Godavari River water, Nashik (Maharashtra) ». Environment Conservation Journal 11, n^o 1&2 (18 juin 2010) : 41–45. http://dx.doi.org/10.36953/ecj.2010.1208.

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The physico-chemical characteristics influence the planktonic population whereas primary productivity depends upon the photosynthetic activity of phytoplankton. The productivity is nothing but the amount of organic matter produced by phytoplankton under a unit area of water surface thus influenced by physico-chemicals parameters. The present paper deals with seasonal variations (winter, summer, monsoon) of parameters like Temp, Turbidity, pH, Free CO2, DO, Nitrates, Phosphates, Planktonic community, along with primary production of Godavari river water at Nashik during November 2002 to October 2003. It was observed that the abiotic parameters are in direct correlation with the biota of an aquatic ecosystem. The planktonic community showed direct correlation with primary productivity i.e. maximum in the summer and minimum in the winter.

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Anderson, T. R., W. C. Gentleman et A. Yool. « EMPOWER-1.0 : an Efficient Model of Planktonic ecOsystems WrittEn in R ». Geoscientific Model Development Discussions 8, n^o 1 (5 janvier 2015) : 53–140. http://dx.doi.org/10.5194/gmdd-8-53-2015.

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Abstract. Modelling marine ecosystems requires insight and judgement when it comes to deciding upon appropriate model structure, equations and parameterisation. Many processes are relatively poorly understood and tough decisions must be made as to how to mathematically simplify the real world. Here, we present an efficient plankton modelling testbed, EMPOWER-1.0, coded in the freely available language R. The testbed uses simple two-layer "slab" physics whereby a seasonally varying mixed layer which contains the planktonic marine ecosystem is positioned above a deep layer that contains only nutrient. As such, EMPOWER-1.0 provides a readily available and easy to use tool for evaluating model structure, formulations and parameterisation. The code is transparent and modular such that modifications and changes to model formulation are easily implemented allowing users to investigate and familiarise themselves with the inner workings of their models. It can be used either for preliminary model testing to set the stage for further work, e.g., coupling the ecosystem model to 1-D or 3-D physics, or for undertaking front line research in its own right. EMPOWER-1.0 also serves as an ideal teaching tool. In order to demonstrate the utility of EMPOWER-1.0, we carried out both a parameter tuning exercise and structural sensitivity analysis. Parameter tuning was demonstrated for four contrasting ocean sites, focusing on Station India in the North Atlantic (60° N, 20° W), highlighting both the utility of undertaking a planned sensitivity analysis for this purpose, yet also the subjectivity which nevertheless surrounds the choice of which parameters to tune. Structural sensitivity tests were then performed comparing different equations for calculating daily depth-integrated photosynthesis, as well as mortality terms for both phytoplankton and zooplankton. Regarding the calculation of daily photosynthesis, for example, results indicated that the model was relatively insensitive to the choice of photosynthesis–irradiance curve, but markedly sensitive to the method of calculating light attenuation in the water column. The work highlights the utility of EMPOWER1.0, and simple models in general, as a means of comprehending, diagnosing and formulating equations for the dynamics of marine ecosystems.

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Hernández, Nancy, et Randi Guerrero-Ríos. « Ecosystem approach to semi-intensive cultivation of Penaeus vannamei ». Revista de la Facultad de Agronomía, Universidad del Zulia 40, Supplement (18 décembre 2023) : e2340Spl07. http://dx.doi.org/10.47280/revfacagron(luz).v40.supl.07.

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The ecosystem approach to semi-intensive culture of Penaeus vannamei is crucial for understanding and managing water quality and planktonic communities in aquaculture systems. This study focuses on analyzing the interrelationship between structural and functional elements, using phytoplankton and zooplankton as bioindicators of water quality and trophic conditions. The objective is to provide detailed information on the dynamics of these communities in culture systems, which will improve survival, feed conversion and shrimp production. A systematic review was carried out using specific keywords in relevant scientific databases, which made it possible to collect updated and relevant information on the topic. The discussion focuses on the importance of phytoplankton as a primary producer, its influence on water quality and its role in the diet of shrimp. Recommendations for maintaining a beneficial balance of phytoplankton communities in cropping systems are detailed. Furthermore, the role of zooplankton as a crucial link in the food chain is analyzed, providing recommendations on the desirable amount of zooplankton in semi-intensive farming. Strategies to address challenges related to primary productivity and food chains in culture ponds are also discussed. In conclusion, this study highlights the importance of the ecosystem approach in shrimp farming, underlining the need to understand and manage planktonic communities to achieve successful and sustainable aquaculture

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Zhang, Chang Ik, Anne Babcock Hollowed, Jae-Bong Lee et Do-Hoon Kim. « An IFRAME approach for assessing impacts of climate change on fisheries ». ICES Journal of Marine Science 68, n^o 6 (1 janvier 2011) : 1318–28. http://dx.doi.org/10.1093/icesjms/fsr073.

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Abstract Zhang, C. I., Hollowed, A. B., Lee, J-B., and Kim, D-H. 2011. An IFRAME approach for assessing impacts of climate change on fisheries. – ICES Journal of Marine Science, 68: 1318–1328. A new assessment framework is proposed for evaluating the performance of management strategies relative to the goals of an ecosystem approach to management (EAM) under different climate change scenarios. Earlier studies have demonstrated how global climate model simulations from the Intergovernmental Panel on Climate Change can be used to force regional ocean circulation models and forecast regional changes in bottom-up forcing. We extend this approach to assess the ecosystem impacts of resource use and climate change in marine ecosystems, by developing an Integrated Fisheries Risk Analysis Method for Ecosystems (IFRAME) framework. The IFRAME approach tracks climate change impacts on the flow of energy through the planktonic foodweb using NEMURO and projects the implications of these shifts in bottom-up forcing on the fisheries foodweb using Ecopath with Ecosim. Resource management scenarios are developed and incorporated into the projection framework by characterizing the action for changes in fishing mortality or availability of resources. An integrated suite of ecosystem status indicators are proposed to assess the performance of management scenarios relative to the goals of an EAM. These ecosystem status indicators track four key management objectives of the ecosystem: sustainability, biodiversity, habitat quantity, and quality and socio-economic status.

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Matveev, V. F., et L. K. Matveeva. « Seasonal succession and long-term stability of pelagic community in a productive reservoir ». Marine and Freshwater Research 56, n^o 8 (2005) : 1137. http://dx.doi.org/10.1071/mf04289.

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In Lake Hume, a reservoir located in an active agricultural zone of the Murray River catchment, Australia, time series for the abundances of phytoplankton and zooplankton taxa, monitored from 1991 through to 1996, were stationary (without trends), and plankton taxonomic composition did not change. This indicated ecosystem resilience to strong fluctuations in reservoir water level, and to other potential agricultural impacts, for example eutrophication and pollution. Although biological stressors such as introduced fish and invertebrate predators are known to affect planktonic communities and reduce biodiversity in lakes, high densities of planktivorous stages of alien European perch (Perca fluviatilis) and the presence of carp (Cyprinus carpio) did not translate into non-stationary time series or declining trends for plankton in Lake Hume. However, the seasonal successions observed in the reservoir in different years did not conform well to the Plankton Ecology Group (PEG) model. Significant deviations of the Lake Hume successional pattern from the PEG model included maxima for phytoplankton abundance being in winter and the presence of a clear water phase without large zooplankton grazers. The instability of the water level in Lake Hume probably causes the dynamics of most planktonic populations to be less predictable, but did not initiate the declining trends that have been observed in some other Australian reservoirs. Both the PEG model and the present study suggest that hydrology is one of the major drivers of seasonal succession.

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Hannisdal, Bjarte, Kristian Agasøster Haaga, Trond Reitan, David Diego et Lee Hsiang Liow. « Common species link global ecosystems to climate change : dynamical evidence in the planktonic fossil record ». Proceedings of the Royal Society B : Biological Sciences 284, n^o 1858 (12 juillet 2017) : 20170722. http://dx.doi.org/10.1098/rspb.2017.0722.

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Common species shape the world around us, and changes in their commonness signify large-scale shifts in ecosystem structure and function. However, our understanding of long-term ecosystem response to environmental forcing in the deep past is centred on species richness, neglecting the disproportional impact of common species. Here, we use common and widespread species of planktonic foraminifera in deep-sea sediments to track changes in observed global occupancy (proportion of sampled sites at which a species is present and observed) through the turbulent climatic history of the last 65 Myr. Our approach is sensitive to relative changes in global abundance of the species set and robust to factors that bias richness estimators. Using three independent methods for detecting causality, we show that the observed global occupancy of planktonic foraminifera has been dynamically coupled to past oceanographic changes captured in deep-ocean temperature reconstructions. The causal inference does not imply a direct mechanism, but is consistent with an indirect, time-delayed causal linkage. Given the strong quantitative evidence that a dynamical coupling exists, we hypothesize that mixotrophy (symbiont hosting) may be an ecological factor linking the global abundance of planktonic foraminifera to long-term climate changes via the relative extent of oligotrophic oceans.

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Santana, Claudeilton Severino de, Ralf Schwamborn, Sigrid Neumann-Leitão, Manuel de Jesus Flores Montes et Simone Maria de Albuquerque Lira. « Spatio-temporal variation of planktonic decapods along the leeward coast of the Fernando de Noronha archipelago, Brazil ». Brazilian Journal of Oceanography 66, n^o 1 (mars 2018) : 1–14. http://dx.doi.org/10.1590/s1679-87592018147206601.

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Abstract Tropical island environments are considered hotspots due to their high diversity, endemism and ecological importance. However, reports that discuss the composition and ecology of planktonic decapods in these environments are still very few. In order to ascertain the composition, abundance and spatial-temporal distribution of planktonic decapods, zooplankton samples were taken by means of sub-surface hauls with a standard plankton net of 300 µm mesh size. Sampling was carried out at five stations in the nearshore leeward area of the Fernando de Noronha archipelago, in July and December 2013 and June and November 2014. A total of 22 decapod taxa were recorded, among which the most abundant were Brachyura (zoeae), Clibanarius sp., Caridea and Callianassidae. Characteristic annual distribution and temporal tendencies were observed for the larvae of the hermit crab Clibanarius sp. and for the larvae of burrowing shrimps (Callianassidae). Some taxa showed differences between sampling stations. In general, higher abundances were observed in the southern (downstream) stations of the island (Baía dos Golfinhos and Cacimba do Padre), and lower abundances in the northernmost (upstream) station (Porto de Santo Antônio), indicating the existence of larval retention in the nearshore coastal zone of this oceanic island ecosystem.

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Madin, Laurence P., Stephen M. Bollens, Erich Horgan, Mari Butler, Jeffrey Runge, Barbara K. Sullivan, Grace Klein-Macphee et al. « Voracious planktonic hydroids : unexpected predatory impact on a coastal marine ecosystem ». Deep Sea Research Part II : Topical Studies in Oceanography 43, n^o 7-8 (1996) : 1823–29. http://dx.doi.org/10.1016/s0967-0645(96)00038-0.

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Barnett, Arthur M., et Andrew E. Jahn. « Pattern and persistence of a nearshore planktonic ecosystem off Southern California ». Continental Shelf Research 7, n^o 1 (janvier 1987) : 1–25. http://dx.doi.org/10.1016/0278-4343(87)90060-4.

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Laas, Peeter, Kelly Ugarelli, Rafael Travieso, Sandro Stumpf, Evelyn E. Gaiser, John S. Kominoski et Ulrich Stingl. « Water Column Microbial Communities Vary along Salinity Gradients in the Florida Coastal Everglades Wetlands ». Microorganisms 10, n^o 2 (20 janvier 2022) : 215. http://dx.doi.org/10.3390/microorganisms10020215.

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Planktonic microbial communities mediate many vital biogeochemical processes in wetland ecosystems, yet compared to other aquatic ecosystems, like oceans, lakes, rivers or estuaries, they remain relatively underexplored. Our study site, the Florida Everglades (USA)—a vast iconic wetland consisting of a slow-moving system of shallow rivers connecting freshwater marshes with coastal mangrove forests and seagrass meadows—is a highly threatened model ecosystem for studying salinity and nutrient gradients, as well as the effects of sea level rise and saltwater intrusion. This study provides the first high-resolution phylogenetic profiles of planktonic bacterial and eukaryotic microbial communities (using 16S and 18S rRNA gene amplicons) together with nutrient concentrations and environmental parameters at 14 sites along two transects covering two distinctly different drainages: the peat-based Shark River Slough (SRS) and marl-based Taylor Slough/Panhandle (TS/Ph). Both bacterial as well as eukaryotic community structures varied significantly along the salinity gradient. Although freshwater communities were relatively similar in both transects, bacterioplankton community composition at the ecotone (where freshwater and marine water mix) differed significantly. The most abundant taxa in the freshwater marshes include heterotrophic Polynucleobacter sp. and potentially phagotrophic cryptomonads of the genus Chilomonas, both of which could be key players in the transfer of detritus-based biomass to higher trophic levels.

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Holm, Henry C., Helen F. Fredricks, Shavonna M. Bent, Daniel P. Lowenstein, Justin E. Ossolinski, Kevin W. Becker, Winifred M. Johnson, Kharis Schrage et Benjamin A. S. Van Mooy. « Global ocean lipidomes show a universal relationship between temperature and lipid unsaturation ». Science 376, n^o 6600 (24 juin 2022) : 1487–91. http://dx.doi.org/10.1126/science.abn7455.

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Global-scale surveys of plankton communities using “omics” techniques have revolutionized our understanding of the ocean. Lipidomics has demonstrated the potential to add further essential insights on ocean ecosystem function but has yet to be applied on a global scale. We analyzed 930 lipid samples across the global ocean using a uniform high-resolution accurate-mass mass spectrometry analytical workflow, revealing previously unknown characteristics of ocean planktonic lipidomes. Focusing on 10 molecularly diverse glycerolipid classes, we identified 1151 distinct lipid species, finding that fatty acid unsaturation (i.e., number of carbon-carbon double bonds) is fundamentally constrained by temperature. We predict substantial declines in the essential fatty acid eicosapentaenoic acid over the next century, which are likely to have serious deleterious effects on economically critical fisheries.

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Mangolte, Inès, Marina Lévy, Clément Haëck et Mark D. Ohman. « Sub-frontal niches of plankton communities driven by transport and trophic interactions at ocean fronts ». Biogeosciences 20, n^o 15 (11 août 2023) : 3273–99. http://dx.doi.org/10.5194/bg-20-3273-2023.

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Abstract. Observations and theory have suggested that ocean fronts are ecological hotspots, associated with higher diversity and biomass across many trophic levels. The hypothesis that these hotspots are driven by frontal nutrient injections is seemingly supported by the frequent observation of opportunistic diatoms at fronts, but the behavior of the rest of the plankton community is largely unknown. Here we investigate the organization of planktonic communities across fronts by analyzing eight high-resolution transects in the California Current Ecosystem containing extensive data for 24 groups of bacteria, phytoplankton, and zooplankton. We find that a distinct frontal plankton community characterized by enhanced biomass of not only diatoms and copepods but many other groups of plankton such as chaetognaths, rhizarians, and appendicularians emerges over most fronts. Importantly, we find spatial variability at a finer scale (typically 1–5 km) than the width of the front itself (typically 10–30 km) with peaks of different plankton taxa at different locations across the width of a front. Our results suggest that multiple processes, including horizontal stirring and biotic interactions, are responsible for creating this fine-scale patchiness.

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Agusti, Susana, Lorena Vigoya et Carlos Manuel Duarte. « Annual plankton community metabolism in estuarine and coastal waters in Perth (Western Australia) ». PeerJ 6 (26 juin 2018) : e5081. http://dx.doi.org/10.7717/peerj.5081.

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The planktonic metabolic balance that is the balance between gross primary production (GPP) and community respiration (CR) was determined in Matilda Bay (estuarine) and Woodman Point (coastal) in Perth, Western Australia. The rates of net community production (NCP = GPP – CR) and the ratio between GPP and CR (P/R) were assessed to evaluate whether the metabolic balance in the two coastal locations tends to be net autotrophic (production exceeding community respiration) or net heterotrophic (respiration exceeding production). We also analyzed environmental variability by measuring temperature, salinity, and nutrients and chlorophyll a concentration. Samples were collected biweekly from March 2014 to March 2015. During the study period the metabolic rates were three times higher in Matilda Bay than in Woodman Point. The predominant metabolism was net autotrophic at both sites with P/R ratios >1 in the majority of the sampling dates. In Matilda Bay, the metabolic rates were negatively correlated with salinity denoting river dynamics influence, and positively with chlorophyll a. In Woodman Point only the GPP was positively correlated with chlorophyll a. The positive correlation between P/R ratio and GPP in Matilda Bay and the positive correlations between the metabolic rates and chlorophyll a suggest that factors controlling autotrophic processes are modulating the planktonic metabolic balance in the coastal marine ecosystem in Perth. Significant correlations were found between CR and GPP-standardized to chlorophyll a and water temperature. The net autotrophic metabolic balance indicates that in both ecosystems planktonic communities are acting as a sink of CO2 and as a source of organic matter and oxygen to the system and are able to export organic matter to other ecosystems.

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Amin, AKM Rohul, Md Rakibuzzaman Shah, Md Mahmood Alam, Imran Hoshan et Md Abu Zafar. « Study on the Present Status of Endangered Fishes and Productivity of Teesta River Closest to Barrage Region ». Research in Agriculture Livestock and Fisheries 7, n^o 3 (31 décembre 2020) : 577–89. http://dx.doi.org/10.3329/ralf.v7i3.51730.

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This study was conducted to monitor the present condition of endangered fishes and productivity of Teesta river closest to Teesta barrage situated in the Lalmonirhat district of Bangladesh. Water and sediment samples were collected twice in a month during the study period from six different (3 upstream and 3 downstream) sites with three replications for each. Required information about threatened fishes was collected from the sampling region associated fishermen and fish markets. The study disclosed over 50 threatened fish species in Teesta river including several threatened fishes namely Bagarius bagarius, Sisor rabdophorus etc. The commonly available endangered fishes were Macrognathus aculiatus, Mastacembelus armatus, Barilius tileo, Raiamas bola, Botia dario, B. lohachata etc. which are rarely available in nationwide. Planktonic flora and fauna determination revealed that comparatively higher density of plankton (n >11500 per liter) as well as more number of planktonic flora (>21 nos.) and fauna (>9 nos.) were monitored in the early monsoon and monsoon season (April-September) and comparatively lower planktonic density (n<10000 per liter) and less number were found in premonsoon season (January-February). The investigation of benthic fauna showed that the riverine ecosystem near to barrage contained 16 species of macro-benthos from different groups. Lastly, it can be noticed that it is very essential to take all effective necessary actions to provide good productivity and conserve the ichthyo diversity of Teesta river that will help to conserve the commonly available endangered and critically endangered fishes of Teesta river. Res. Agric., Livest. Fish.7(3): 577-589, December 2020

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Aquino, Eveline P., Gislayne C. P. Borges, Marcos Honorato-da-Silva, José Zanon O. Passavante et Maria G. G. S. Silva-Cunha. « Phytoplankton in a tropical estuary, Northeast Brazil : composition and life forms ». Check List 11, n^o 3 (21 avril 2015) : 1633. http://dx.doi.org/10.15560/11.3.1633.

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We aimed verify the composition of the phytoplankton community and this life forms that occur in the Capibaribe River estuary, Pernambuco, Brazil. This is a highly impacted ecosystem by anthropic activities. We collected samples of the phytoplankton community at three stations, during three months of each season: dry, from October to December 2010; rainy, from May to July 2011. We collected samples during the low and high tide, at the spring tide. We classified the species based on life forms. We identified 127 taxa, and the majority of species were freshwater planktonic form (FP; 30%), followed by marine oceanic planktonic (MOP; 25%), marine neritic tichoplanktonic (MNT; 22%) and planktonic (MNP; 19%,), and tichoplanktonic estuarine (TE; 3%) and freshwater (TF; 1%). The majority of species identified were diatoms, since it assumes the most variability of life forms, therefore enabling its presence in the different portions at the estuary.

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García-Comas, Carmen, Akash R. Sastri, Lin Ye, Chun-Yi Chang, Fan-Sian Lin, Min-Sian Su, Gwo-Ching Gong et Chih-hao Hsieh. « Prey size diversity hinders biomass trophic transfer and predator size diversity promotes it in planktonic communities ». Proceedings of the Royal Society B : Biological Sciences 283, n^o 1824 (10 février 2016) : 20152129. http://dx.doi.org/10.1098/rspb.2015.2129.

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Body size exerts multiple effects on plankton food-web interactions. However, the influence of size structure on trophic transfer remains poorly quantified in the field. Here, we examine how the size diversity of prey (nano-microplankton) and predators (mesozooplankton) influence trophic transfer efficiency (using biomass ratio as a proxy) in natural marine ecosystems. Our results support previous studies on single trophic levels: transfer efficiency decreases with increasing prey size diversity and is enhanced with greater predator size diversity. We further show that communities with low nano-microplankton size diversity and high mesozooplankton size diversity tend to occur in warmer environments with low nutrient concentrations, thus promoting trophic transfer to higher trophic levels in those conditions. Moreover, we reveal an interactive effect of predator and prey size diversities: the positive effect of predator size diversity becomes influential when prey size diversity is high. Mechanistically, the negative effect of prey size diversity on trophic transfer may be explained by unicellular size-based metabolic constraints as well as trade-offs between growth and predation avoidance with size, whereas increasing predator size diversity may enhance diet niche partitioning and thus promote trophic transfer. These findings provide insights into size-based theories of ecosystem functioning, with implications for ecosystem predictive models.

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Tsuchiya, K., A. Kohzu, VS Kuwahara, SiS Matsuzaki, M. Denda et K. Hirabayashi. « Differences in regulation of planktonic and epilithic biofilm bacterial production in the middle reaches of a temperate river ». Aquatic Microbial Ecology 87 (17 juin 2021) : 47–60. http://dx.doi.org/10.3354/ame01968.

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To clarify the governing factors of planktonic and epilithic bacterial production (BP) and to quantify their relative contributions to the carbon cycle, we investigated the seasonal variation and regulatory factors of planktonic and epilithic BP in the middle reaches of the Shinano River, Japan, ecosystem from February 2019 to May 2020. Sampling was conducted at 3 stations: upper stream riffle, upper stream pool, and lower stream riffle, where current velocity, water depth, and bed shear stress were distinct. Planktonic and biofilm BP ranged from 5.5 to 466 mgC m-3 d-1 and 2.9 to 132 mgC m-2 d-1, respectively, showing clear seasonal variation. Biofilm BP was higher in the upper stream riffle than at the other stations, where no spatial variation in planktonic BP was observed. Generalized linear models suggest that BP was primarily regulated by water temperature. Additionally, planktonic BP was significantly correlated with dissolved organic carbon, suggesting carbon limitation. Biofilm BP showed no evidence of resource limitation (nutrients and organic matter), but was significantly explained by current velocity and station. The results suggest that although seasonality is dominant in biofilm BP variation, spatial differences are significant within the seasonal variability. Moreover, current velocity and bottom shear stress related to local geomorphologies such as riffles and pools affect substrate supply rate and biofilm formation processes, regulating biofilm BP variation. This study demonstrated different regulatory factors of planktonic and biofilm BP in the middle reaches of a temperate river.

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de Santana, Erika Flávia Crispim, Amanda Lacerda Alves, André De Melo Santos, Maria Da Gloria G. S. Cunha, Carlos Daniel Perez et Paula Braga Gomes. « Trophic ecology of the zoanthidPalythoa caribaeorum(Cnidaria : Anthozoa) on tropical reefs ». Journal of the Marine Biological Association of the United Kingdom 95, n^o 2 (24 novembre 2014) : 301–9. http://dx.doi.org/10.1017/s0025315414001726.

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This study examined the trophic ecology of the zoanthidPalythoa caribaeorumin tropical reefs and evaluated its role in the energy flow in that ecosystem. Colonies of this species were sampled in the infralittoral zone of reefs in north-eastern Brazil in 2008. We calculated the richness, total abundance, relative abundance and frequency of occurrence of prey items. The biovolumes and weighted biovolumes of prey were calculated to characterize the most important food items in terms of their biomasses. To evaluate the selectivity, zoanthid and plankton samples were collected in 2010. Pennate diatoms were the most abundant and most frequent prey and, together with invertebrate eggs, constituted the most important food items in terms of their biomasses. There were no significant differences in abundance or richness among the different beaches studied, nor between the different seasons. The mean size of prey items within the polyps was significantly smaller than of the general plankton, indicating thatP. caribaeorumselected for (or limited) certain prey sizes. This species predominantly fed on diatoms, and did not take advantage of many other prey items abundant in the plankton. Our results indicate thatP. caribaeorumis suspensivorous and feeds principally on small phytoplankton. As this species is prey for benthic organisms such as polychaetes and nektonic organisms, our results indicate the importance of this zoanthid in tropical reef ecosystems as a primary consumer that serves as an energy transfer link between the planktonic environment and the nektonic and benthic spheres.

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