Sources of Organic Matter for Reservoir Fish Production: A Trophic-Dynamics Analysis

Adams, S.M.; Kimmel, Bruce L.; Ploskey, Gene R.

doi:10.1139/f83-170

Cited by 75 publications

(45 citation statements)

References 11 publications

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“…We use a standard definition of trophic level (28,29), defined in terms of carbon and modified slightly to allow for mixotrophic nutrition. For a community of N plankton populations, the trophic level T i of population i is given by…”

Section: Methodsmentioning

confidence: 99%

Marine mixotrophy increases trophic transfer efficiency, mean organism size, and vertical carbon flux

Ward

Follows

2016

Proc. Natl. Acad. Sci. U.S.A.

266

275

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Mixotrophic plankton, which combine the uptake of inorganic resources and the ingestion of living prey, are ubiquitous in marine ecosystems, but their integrated biogeochemical impacts remain unclear. We address this issue by removing the strict distinction between phytoplankton and zooplankton from a global model of the marine plankton food web. This simplification allows the emergence of a realistic trophic network with increased fidelity to empirical estimates of plankton community structure and elemental stoichiometry, relative to a system in which autotrophy and heterotrophy are mutually exclusive. Mixotrophy enhances the transfer of biomass to larger sizes classes further up the food chain, leading to an approximately threefold increase in global mean organism size and an ∼35% increase in sinking carbon flux.arine ecosystems provide essential nutrition to more than half the world's population via fisheries (1) and mediate global cycles of climatically important elements including carbon (2). Current models of marine biogeochemical cycles assume that the plankton can be clearly divided into two mutually exclusive guilds: the autotrophic phytoplankton and the heterotrophic zooplankton. According to this view, phytoplankton are responsible for all photosynthetic carbon fixation, ultimately controlled by the supply and consumption of inorganic nutrients.There is clear evidence that such a strict dichotomy between producers and consumers does not reflect the true nature of marine microbial communities. Autotrophic and heterotrophic traits are not mutually exclusive, and a large and increasing number of plankton taxa have been shown to simultaneously exploit both inorganic resources and living prey (3). These mixotrophic plankton, found throughout the eukaryotic tree of life (4), and particularly in the 2-to 200-μm size range (5-7), can sustain photosynthesis even when chronically outcompeted for the most-limiting inorganic nutrient, in clear contrast to the way we typically describe and model marine systems (8).Although mixotrophy is known to be common throughout the global ocean (6, 7), its contribution to net community production is difficult to quantify, and its integrated impact on global biogeochemical cycles remains unknown. Numerical simulations provide a platform to address these questions, but to date, no global ocean models have resolved this important lifestyle. Here, we examine the global role of mixotrophy in a numerical "thought experiment," comparing two simulations of the marine plankton food web in the global ocean (9) that differ only in their representation of trophic strategy (Fig. 1). The traditional "two-guild" model encapsulates the default view of the marine ecosystem, with each of the 10 simulated size classes divided into separate phytoplankton and zooplankton populations. In the alternative "mixotrophy" model, this unrealistically strict distinction is not made, and each size class contains just one population that is capable of both inorganic resource uptake and predation, dependent ...

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Section: Methodsmentioning

confidence: 99%

Marine mixotrophy increases trophic transfer efficiency, mean organism size, and vertical carbon flux

Ward

Follows

2016

Proc. Natl. Acad. Sci. U.S.A.

266

275

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“…Furthermore, if trophic levels are defined as taking integer values only, the implied abrupt jumps in trophic level will make it difficult to track the dynamics of evolving food webs. Following Odum and Heald (1975) and Adams et al (1983), we define a morph's realvalued fractional trophic level as 1 plus the average trophic level of its prey. Denoting by t i the fractional trophic level of morph i = 0, .…”

Section: A2 Definition Of Trophic Levelsmentioning

confidence: 99%

Emergence and maintenance of biodiversity in an evolutionary food-web model

et al. 2010

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Ecological communities emerge as a consequence of gradual evolution, speciation, and immigration. In this study, we explore how these processes and the structure of the evolved food webs are affected by species-level properties. Using a model of biodiversity formation that is based on body size as the evolving trait and incorporates gradual evolution and adaptive radiation, we investigate how conditions for initial diversification relate to the eventual diversity of a food web. We also study how trophic interactions, interference competition, and energy availability affect a food web's maximum trophic level and contrast this with conditions for high diversity. We find that there is not always a positive relationship between conditions that promote initial diversification and eventual diversity, and that the most diverse food webs often do not have the highest trophic levels.

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“…Trophic position (s) was estimated with a method used frequently in the literature (Adams et al 1983;Post and Takimoto 2007;Vander Zanden and Rasmussen 1996):…”

Section: Samplingmentioning

confidence: 99%

Bythotrephes invasion elevates trophic position of zooplankton and fish: implications for contaminant biomagnification

2011

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We estimated the effects of Bythotrephes longimanus invasion on the trophic position (TP) of zooplankton communities and lake herring, Coregonus artedi. Temporal changes in lacustrine zooplankton communities following Bythotrephes invasion were contrasted with non-invaded reference lakes, and along with published information on zooplankton and herring diets, formed the basis of estimated changes in TP. The TP of zooplankton communities and lake herring increased significantly following the invasion of Bythotrephes, whereas TP in reference lakes decreased (zooplankton) or did not change significantly (lake herring) over a similar time frame. Elevated TP following Bythotrephes invasion was most prominent in lakes that also supported the glacial relict, Mysis diluvania, suggesting a possible synergistic interaction between these two species on zooplankton community composition. Our analysis indicated that elevated TPs of zooplankton communities and lake herring are not simply due to the presence of Bythotrephes, but rather reflect changes in the zooplankton community induced by Bythotrephes; namely, a major reduction in the proportion of herbivorous cladoceran biomass and a concomitant increase in the proportion of omnivorous and/or predatory copepod biomass in invaded lakes. We demonstrated that increases in TP of the magnitude reported here can lead to substantial increases in fish contaminant concentrations. In light of these results, we discuss potential mechanisms that may be responsible for the disconnect between empirical and theoretical evidence that mid-trophic level species invasions (e.g., Bythotrephes) elevate contaminant burdens of consumer species, and provide testable hypotheses to evaluate these mechanisms.

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Sources of Organic Matter for Reservoir Fish Production: A Trophic-Dynamics Analysis

Cited by 75 publications

References 11 publications

Marine mixotrophy increases trophic transfer efficiency, mean organism size, and vertical carbon flux

Marine mixotrophy increases trophic transfer efficiency, mean organism size, and vertical carbon flux

Emergence and maintenance of biodiversity in an evolutionary food-web model

Bythotrephes invasion elevates trophic position of zooplankton and fish: implications for contaminant biomagnification

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