The Role of Zooplankton Grazing in the Maintenance of Phytoplankton Species Richness [microform] PDF Download

Author: Edward McCauley
Publisher: Université d'Ottawa = University of Ottawa, [198-?]
ISBN:
Category : Phytoplankton
Languages : en
Pages : 320

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Author: Edward McCauley
Publisher:
ISBN:
Category : Phytoplankton
Languages : en
Pages : 320

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Book Description

Author: Azma Hanim Ismail
Publisher:
ISBN:
Category : Freshwater phytoplankton
Languages : en
Pages : 401

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Book Description
An investigation of whether herbivorous zooplankton plays a major role in the maintenance of high phytoplankton species richness in freshwater bodies.

Author: Maria Alexandra Teodosio
Publisher: CRC Press
ISBN: 1351021818
Category : Nature
Languages : en
Pages : 292

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Book Description
This book aims at providing students and researchers an advanced integrative overview on zooplankton ecology, covering marine and freshwater organisms, from microscopic phagotrophic protists, to macro-jellyfishes and active fish larvae. The first book section addresses zooplanktonic organisms and processes, the second section is devoted to zooplankton spatial and temporal distribution patterns and trophic dynamics, and the final section is dedicated to emergent methodological approaches (e.g., omics). Book chapters include comprehensive synthesis, observational and manipulative studies, and sediment-based analysis, a vibrant imprint of benthic-pelagic coupling and ecosystem connectivity. Most chapters also address the impacts of anticipated environmental changes (e.g., warming, acidification).

Author: Rainer Kiko
Publisher: Frontiers Media SA
ISBN: 2889639827
Category : Science
Languages : en
Pages : 164

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This eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contact.

Author: Joseph C. Makarewicz
Publisher:
ISBN:
Category : Eutrophication
Languages : en
Pages : 280

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Author:
Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 88

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Author: Kevin Matthew Archibald
Publisher:
ISBN:
Category :
Languages : en
Pages : 135

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In this thesis, I explore two topics in plankton ecology with a combination of models and observations. First, I investigate the contribution of zooplankton diel vertical migration (DVM) to the vertical flux of carbon as part of the biological pump. I do this by constructing and analyzing a global model that includes DVM and is driven by satellite-based estimates of primary productivity. There has long been speculation about the significance of DVM to the biological pump, but quantitative estimates of its impact are rare. I estimate that DVM constitutes approximately 16% of the global carbon export flux associated with the biological pump and that the relative contribution of DVM is higher in subtropical latitudes. In later chapters, I build two nutrient-phytoplankton-zooplankton (NPZ) models with different levels of complexity to evaluate the role of nutrient supply and grazing in promoting phytoplankton diversity. Zooplankton switching plays a significant role in promoting diversity because it allows competing phytoplankton types to coexist in situations that would otherwise lead to competitive exclusion. When implemented in a size-structured NPZ model, stronger switching increases the evenness of the distribution of biomass between coexisting size classes, which is used as a proxy for taxonomic diversity. I also describe a particular characteristic of the Kill-the-Winner functional response (used in the NPZ models), which I have termed synergistic grazing. Synergistic grazing occurs when the grazing rate on one phytoplankton type increases as the biomass of an alternative phytoplankton type increases. This characteristic can result in unintuitive model dynamics. Finally, I describe patterns in phytoplankton community size structure in the shelfbreak region of the Northeast U.S. Shelf using high-resolution flow-cytometry measurements. I find that enhancement of phytoplankton biovolume at the shelfbreak front is common during the springtime, but these enhancement events are not associated with consistent changes in community size structure. I evaluate these results in the context of hypotheses generated based on my analysis of the NPZ models.

Author: Onur Karakuş
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Book Description
Marine zooplankton, i.e., heterotrophic marine plankton, serve as trophic links between primary producers and higher trophic levels, and as recyclers for nutrients and carbon in the pelagic ecosystem. In addition, they play a major role for the carbon export flux due to fecal pellet production and fragmentation of particles. They are distributed all over the ocean and constitute a large variety of organisms. Because of large uncertainties in the estimation of parameters and the forms of equations, zooplankton are often parameterized in strongly simplified forms in ocean biogeochemical models. Nowadays, however, increasing data availability from experiments and observations makes it possible to implement different zooplankton functional types in models. This thesis presents the implementation of new zooplankton functional types into an ocean biogeochemical model. Subsequently, the sensitivity of net primary production, carbon export and nutrients to the implementation of these new zooplankton functional types was analyzed. In my thesis, I use a global setup of the biogeochemical model Regulated Ocean Ecosystem Model (REcoM) coupled with the Finite Element Sea-Ice Ocean Model (FESOM). I implemented an explicit parametrization of micro-, meso-, and polar macrozooplankton based on process rates and biomass observations from the literature, as well as a representation of fast-sinking detritus. This extended version of REcoM was used to analyze the role of zooplankton for carbon export, nutrient recycling, and phytoplankton bloom phenology. In a second step, a new sinking routine that considers the roles of mineral ballasting and seawater viscosity on the particle sinking speed and the effect of oxygen on remineralization rates was added to the model. This set-up was used to assess the role of each factor (ballast minerals, seawater viscosity, and oxygen concentration) for the export and transfer efficiencies of carbon, i.e. the amount of particulate organic carbon that is exported across the euphotic depth and reaches the deep ocean. The implementation of the new zooplankton groups changes the carbon transfer efficiency and net primary production in the model. Publication I and III highlight the influence of zooplankton on the transfer efficiency of carbon. Publication I shows that the transfer efficiency of carbon reaches up to 50% due to the high biomass of polar macrozooplankton in the Southern Ocean. Similarly, it was illustrated in Publication III that the high mesozooplankton biomass increases the transfer efficiency of carbon to 80% in the Equatorial Pacific. In addition, the model results presented in Publication I and II show the stimulation of net primary production due to the fast recycling of nutrients. After the parametrization of three zooplankton functional types, the new state of the model leads to a 25% increase in annual mean net primary production. In addition to the effects on annual mean bulk fluxes, the more complex representation of zooplankton also affects the timing of phytoplankton blooms and biogeochemical fluxes. Zooplankton fecal pellets constitute an important share of sinking particulate organic carbon depending on the season in the Southern Ocean. In Publication I, it is shown that the typical shift from a dominance of phytodetrital aggregates in spring to zooplankton fecal pellets later in the year is now reasonably reproduced by the model after the implementation of polar macrozooplankton. Zooplankton grazing can play a decisive role in phytoplankton bloom phenology since it is a loss mechanism for phytoplankton. In Publication II, it is shown that the increased loss rates of phytoplankton due to stronger zooplankton grazing lead to the later start of the spring bloom. In addition, nutrient recycling by zooplankton prevents the fast exhaustion of nutrients by phytoplankton and consequently leads to a later end date of the bloom. In the end, the more complex parametrization of zooplankton provides a modeled phytoplankton bloom phenology closer to observations. The results also indicate that the explaining mechanism behind the bloom phenology changes. While the start of the spring bloom is explained better with the 'Critical Depth Hypothesis' in the low grazing scenario, the system aligns with the 'Dilution-Recoupling Hypothesis' in the high grazing loss simulation. Finally, the global spatial distribution of export and transfer efficiencies are analyzed in Publication III. In particular, I examined the impact of ballast minerals, seawater viscosity, and oxygen-dependent remineralization on export and transfer efficiencies. These three processes are often not considered in biogeochemical models. My results show that the global mean of export efficiency across the euphotic zone stays similar ( 13%) when the effects of mineral ballasting, seawater viscosity, and oxygen-dependent remineralization are added to the model. However, the global mean carbon transfer efficiency is more sensitive to these processes and varies between 25% and 32% in different simulations dependent on the representation of these processes. The magnitude of the effect of each process varies spatially. While the effect of ballast minerals can increase the transfer efficiency by a factor of nine in high latitudes and subtropical gyres, including oxygen-dependent remineralization can increase the transfer efficiency by 28% in low latitudes. The influence of seawater viscosity on the transfer efficiency is smaller compared to the other effects, and it increases the transfer efficiency 8% in subtropical gyres. The thesis highlights that the zooplankton compartment in biogeochemical models should not only be treated as a closure term, and zooplankton functional types should be implemented in the global ocean biogeochemical models by using available datasets from the literature. It further underscores that missing out process representations of mechanisms that underlie carbon export has considerable effects on estimated carbon transfer efficiencies in biogeochemical models. Thus, further attention should be paid on the representation of missing processes related to particle formation and sinking.

Author: George Kehayias
Publisher: Nova Science Publishers
ISBN: 9781629486802
Category : Marinbiologi
Languages : en
Pages : 0

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Book Description
Zooplankton organisms comprise very important elements of the structure and function of marine and freshwater ecosystems, not only as consumers of primary production, but also as food items for juvenile stages of several fish species. Moreover, its sensitivity to both man-made and natural changes makes zooplankton quite suitable for assessing alterations in the trophic dynamics and the ecological state of aquatic ecosystems related to changes in nutrient loading and climate. Multi-scale, spatial and temporal relationships between zooplankton variability and environmental heterogeneity are still not satisfactorily understood due to the complexity of the different aquatic ecosystems (considering both biotic and abiotic elements). Thus, the ambition of the present edition is to contribute to the understanding of the role of zooplankton by investigating ecological aspects such as the species diversity, their spatial distribution and seasonal dynamics in relation to the environmental influence in various aquatic ecosystems around the world. Topics discussed in this book include the understanding of the role of zooplankton in the transfer of pollutants through trophic food webs; plankton models to explain red tides; spatial patterns of trophy and zooplankton communities in a tropical urban reservoir; the zooplankton variation in five Greek lakes; the zooplankton community in a nuclear power station cooling reservoir; the spatio-temporal dynamics of cladocera and copepoda in the Danube River; the gelatinous zooplankton in the Namibian upwelling region; and the zooplankton community in relation to the environmental factors in a solar saltern.