Crustacean Zooplankton Food Web Structure in Lakes of Varying Acidity

1991 ◽  
Vol 48 (10) ◽  
pp. 1846-1852 ◽  
Author(s):  
Karl E. Havens
Keyword(s):  
Food Web ◽  
Energy Flow ◽  
Trophic Levels ◽  
Crustacean Zooplankton ◽  
Feeding Strategies ◽  
Food Web Structure ◽  
Acidic Lakes ◽  
The North ◽  
Water Ph ◽  
Adirondack Mountain

Crustacean zooplankton food web models were constructed for 25 softwater United States lakes of varying pH (4.7–7.2). Eight lakes on the North Mountain Plateau of Pennsylvania were sampled in 1987, and data from 17 Adirondack Mountain, NY, and White Mountain, NH, lakes were taken from Confer et al. (1983. Can. J. Fish. Aquat. Sci. 40: 36–42). In the most acidic lakes, the zooplankton food webs were simplified, with only two or three crustacean species; the highest pH lakes contained 6–10 species. Positive relationships were found between lake water pH and species richness, total number of predator–prey interactions, average number of interactions per species, and average generalization of predators. Inverse relationships were found between pH and both the degree of omnivory and cannibalism in the webs, perhaps reflecting the adaptiveness of those feeding strategies under circumstances where energy flow from adjacent trophic levels is reduced. Reduced energy flow may limit the number of trophic levels in the most acidic lakes. Lakes of pH < 5 had only two or three modal trophic levels, while lakes of pH > 5 had three, four, or five levels.

scholarly journals Understanding the structure and functioning of polar pelagic ecosystems to predict the impacts of change

2016 ◽  
Vol 283 (1844) ◽  
pp. 20161646 ◽  
Author(s):  
E. J. Murphy ◽  
R. D. Cavanagh ◽  
K. F. Drinkwater ◽  
S. M. Grant ◽  
J. J. Heymans ◽  
...  
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Energy Flow ◽  
Life Histories ◽  
Trophic Levels ◽  
Individual Species ◽  
Polar Regions ◽  
Ecosystem Structure ◽  
Food Web Structure ◽  
Pelagic Ecosystems

The determinants of the structure, functioning and resilience of pelagic ecosystems across most of the polar regions are not well known. Improved understanding is essential for assessing the value of biodiversity and predicting the effects of change (including in biodiversity) on these ecosystems and the services they maintain. Here we focus on the trophic interactions that underpin ecosystem structure, developing comparative analyses of how polar pelagic food webs vary in relation to the environment. We highlight that there is not a singular, generic Arctic or Antarctic pelagic food web, and, although there are characteristic pathways of energy flow dominated by a small number of species, alternative routes are important for maintaining energy transfer and resilience. These more complex routes cannot, however, provide the same rate of energy flow to highest trophic-level species. Food-web structure may be similar in different regions, but the individual species that dominate mid-trophic levels vary across polar regions. The characteristics (traits) of these species are also different and these differences influence a range of food-web processes. Low functional redundancy at key trophic levels makes these ecosystems particularly sensitive to change. To develop models for projecting responses of polar ecosystems to future environmental change, we propose a conceptual framework that links the life histories of pelagic species and the structure of polar food webs.

scholarly journals Mesoscale variations in the assemblage structure and trophodynamics of mesozooplankton communities of the Adriatic basin (Mediterranean Sea)

2021 ◽  
Author(s):  
Emanuela Fanelli ◽  
Samuele Menicucci ◽  
Sara Malavolti ◽  
Andrea De Felice ◽  
Iole Leonori
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Mediterranean Sea ◽  
Environmental Variables ◽  
Complex Structure ◽  
Assemblage Structure ◽  
Trophic Levels ◽  
Ecosystem Functions ◽  
Food Web Structure ◽  
Adriatic Basin

Abstract. Zooplankton are critical to the functioning of ocean food webs because of their utter abundance and vital ecosystem roles. Zooplankton communities are highly diverse and thus perform a variety of ecosystem functions, thus changes in their community or food web structure may provide evidence of ecosystem alteration. Assemblage structure and trophodynamics of mesozooplantkon communities were examined across the Adriatic basin, the northernmost and most productive basin of the Mediterranean Sea. Samples were collected in June–July 2019 along coast-offshore transects covering the whole western Adriatic side, consistently environmental variables were also recorded. Results showed a clear separation between samples from the northern-central Adriatic and the southern ones, with a further segregation, although less clear, of inshore vs. off-shore stations, the latter mostly dominated in the central and southern stations by gelatinous plankton. Such patterns were mainly driven by chlorophyll-a concentration (as a proxy of primary production) for northern-central stations, i.e. closer to the Po river input, and by temperature and salinity, for southern ones, with the DistLM model explaining 46 % of total variance. The analysis of stable isotopes of nitrogen and carbon allowed to identify a complex food web characterized by 3 trophic levels from herbivores to carnivores, passing through the mixed feeding behavior of omnivores, shifting from phytoplankton/detritus ingestion to microzooplankton. Trophic structure also spatially varied according to sub-area, with the northern-central sub-areas differing from each other and from the southern stations. Our results highlighted the importance of environmental variables as drivers of zooplanktonic communities and the complex structure of their food webs. Disentangling and considering such complexity is crucial to generate realistic predictions on the functioning of aquatic ecosystems, especially in high productive and, at the same time, overexploited area such as the Adriatic Sea.

Catchment land cover influences macroinvertebrate food‐web structure and energy flow pathways in mountain streams

2019 ◽  
Vol 64 (9) ◽  
pp. 1557-1571 ◽  
Author(s):  
Edurne Estévez ◽  
José Manuel Álvarez‐Martínez ◽  
Mario Álvarez‐Cabria ◽  
Christopher T. Robinson ◽  
Tom J. Battin ◽  
...  
Keyword(s):  
Land Cover ◽  
Food Web ◽  
Energy Flow ◽  
Mountain Streams ◽  
Food Web Structure ◽  
Web Structure ◽  
Flow Pathways

Decrease in diatom dominance at lower Si:N ratios alters plankton food webs

2020 ◽  
Vol 42 (4) ◽  
pp. 411-424
Author(s):  
Kriste Makareviciute-Fichtner ◽  
Birte Matthiessen ◽  
Heike K Lotze ◽  
Ulrich Sommer
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Phytoplankton Community ◽  
Plankton Community ◽  
Trophic Levels ◽  
Food Web Structure ◽  
Planktonic Food ◽  
Web Structure ◽  
Copepod Grazing ◽  
Important Food Source

Abstract Many coastal oceans experience not only increased loads of nutrients but also changes in the stoichiometry of nutrient supply. Excess supply of nitrogen and stable or decreased supply of silicon lower silicon to nitrogen (Si:N) ratios, which may decrease diatom proportion in phytoplankton. To examine how Si:N ratios affect plankton community composition and food web structure, we performed a mesocosm experiment where we manipulated Si:N ratios and copepod abundance in a Baltic Sea plankton community. In high Si:N treatments, diatoms dominated. Some of them were likely spared from grazing unexpectedly resulting in higher diatom biomass under high copepod grazing. With declining Si:N ratios, dinoflagellates became more abundant under low and picoplankton under high copepod grazing. This altered plankton food web structure: under high Si:N ratios, edible diatoms were directly accessible food for copepods, while under low Si:N ratios, microzooplankton and phago-mixotrophs (mixoplankton) were a more important food source for mesograzers. The response of copepods to changes in the phytoplankton community was complex and copepod density-dependent. We suggest that declining Si:N ratios favor microzoo- and mixoplankton leading to increased complexity of planktonic food webs. Consequences on higher trophic levels will, however, likely be moderated by edibility, nutritional value or toxicity of dominant phytoplankton species.

scholarly journals Food web structure variability in the surface layer, at a fixed station influenced by the North Western Mediterranean Current

Hydrobiologia ◽  
1996 ◽  
Vol 321 (2) ◽  
pp. 145-153 ◽  
Author(s):  
Urania Christaki ◽  
France Van Wambeke ◽  
Epaminondas D. Christou ◽  
Pascal Conan ◽  
Raymond Gaudy
Keyword(s):  
Surface Layer ◽  
Food Web ◽  
Western Mediterranean ◽  
Food Web Structure ◽  
The North ◽  
Web Structure ◽  
North Western ◽  
Fixed Station

An Inverse Model Analysis of Planktonic Food Webs in Experimental Lakes

1994 ◽  
Vol 51 (9) ◽  
pp. 2034-2044 ◽  
Author(s):  
Alain F. Vézina ◽  
Michael L. Pace
Keyword(s):  
Food Web ◽  
Heterotrophic Bacteria ◽  
Grazing Pressure ◽  
Inverse Methods ◽  
Trophic Levels ◽  
Microbial Food Web ◽  
Food Web Structure ◽  
Planktonic Food ◽  
Size Groups ◽  
The Impact

We used inverse methods to reconstruct carbon flows in experimental lakes where the fish community had been purposely altered. These analyses were applied to three years of data from a reference lake and two experimental lakes located in Gogebic County, Michigan. We reconstructed seasonally averaged flows among two size groups of phytoplankton, heterotrophic bacteria, microzooplankton, cladocerans, and copepods. The inverse analysis produced significantly different flow networks for the different lakes that agreed qualitatively with known chemical and biological differences between lakes and with other analyses of the impact of fish manipulations on food web structure and dynamics. The results pointed to alterations in grazing pressure on the phytoplankton that parallel changes in the size and abundance of cladocerans and copepods among lakes. Estimated flows through the microbial food web indicated low bacterial production efficiencies and small carbon transfers from the microbial food web to the larger zooplankton. This study demonstrates the use of inverse methods to identify and compare flow patterns across ecosystems and suggests that microbial flows are relatively insensitive to changes at the upper trophic levels.

Lake Michigan offshore ecosystem structure and food web changes from 1987 to 2008

2014 ◽  
Vol 71 (7) ◽  
pp. 1072-1086 ◽  
Author(s):  
Mark W. Rogers ◽  
David B. Bunnell ◽  
Charles P. Madenjian ◽  
David M. Warner
Keyword(s):  
Food Web ◽  
Functional Groups ◽  
Lake Michigan ◽  
Neogobius Melanostomus ◽  
Trophic Levels ◽  
Nutrient Concentrations ◽  
Ecosystem Structure ◽  
Bythotrephes Longimanus ◽  
Nutrient Inputs ◽  
Food Web Structure

Ecosystems undergo dynamic changes owing to species invasions, fisheries management decisions, landscape modifications, and nutrient inputs. At Lake Michigan, new invaders (e.g., dreissenid mussels (Dreissena spp.), spiny water flea (Bythotrephes longimanus), round goby (Neogobius melanostomus)) have proliferated and altered energy transfer pathways, while nutrient concentrations and stocking rates to support fisheries have changed. We developed an ecosystem model to describe food web structure in 1987 and ran simulations through 2008 to evaluate changes in biomass of functional groups, predator consumption, and effects of recently invading species. Keystone functional groups from 1987 were identified as Mysis, burbot (Lota lota), phytoplankton, alewife (Alosa pseudoharengus), nonpredatory cladocerans, and Chinook salmon (Oncorhynchus tshawytscha). Simulations predicted biomass reductions across all trophic levels and predicted biomasses fit observed trends for most functional groups. The effects of invasive species (e.g., dreissenid grazing) increased across simulation years, but were difficult to disentangle from other changes (e.g., declining offshore nutrient concentrations). In total, our model effectively represented recent changes to the Lake Michigan ecosystem and provides an ecosystem-based tool for exploring future resource management scenarios.

Is pelagic top-down control in lakes augmented by benthic energy pathways?

2005 ◽  
Vol 62 (6) ◽  
pp. 1422-1431 ◽  
Author(s):  
M Jake Vander Zanden ◽  
Timothy E Essington ◽  
Yvonne Vadeboncoeur
Keyword(s):  
Food Web ◽  
Energy Flow ◽  
Standing Stock ◽  
Fold Increase ◽  
Trophic Dynamics ◽  
Prey Fish ◽  
Top Down ◽  
Food Web Structure ◽  
Contrast Analysis ◽  
Dynamic Perspective

Modern food web studies are typically conducted from a trophic dynamic perspective that focuses on combined roles of top-down and bottom-up forces in regulating food web structure. Recognition of spatial food web subsidies in diverse ecosystems highlights the importance of energy flow as a foundation for understanding trophic dynamics. Here, we consider how different energy flow configurations might affect trophic dynamics in north-temperate lakes. A literature review revealed that littoral piscivores exert top-down control on prey fishes. In contrast, analysis of littoral predator diets indicated extensive omnivory and heavy reliance on zoobenthic prey. We explored this uncoupling between trophic dynamics (piscivores regulate prey fish) and energy flow (zoobenthos in piscivore diets) using a biomass dynamic model. This model compared top-down impacts of a piscivore on prey fishes under two scenarios: consumption of prey fish only and consumption of prey fish plus zoobenthos. The model predicted that elimination of zoobenthivory leads to a 50% reduction in piscivore standing stock and concomitant 2.5-fold increase in prey fish abundance (i.e., zoobenthivory plays a key role in mediating pelagic top-down control). These results highlight the role of benthic–pelagic linkages in regulating trophic dynamics and underscore the value of whole-ecosystem approaches to the study of food webs.

scholarly journals Benthic biodiversity and food web structure in the European sector of the Arctic Ocean during spring time

2018 ◽  
Author(s):  
Barbara Oleszczuk ◽  
Katarzyna Grzelak ◽  
Monika Kędra
Keyword(s):  
Sea Ice ◽  
Food Web ◽  
Barents Sea ◽  
Benthic Communities ◽  
Trophic Levels ◽  
The Arctic ◽  
Feeding Guild ◽  
Food Web Structure ◽  
Web Structure ◽  
Ice Conditions

Arctic marine ecosystems are currently facing sea ice decrease. Changes in the sea ice cover will influence the Organic Matter (OM) fluxes to the bottom and thus benthic communities. We aimed to examine meio- and macrobenthic biodiversity and community structure, and food web, with use of stable isotopes of carbon (δ13C) and nitrogen (δ15N), in relation to depth, sea ice type, and bloom stage. Benthic samples were collected in Svalbard area during spring time in 2015 and 2016 along with samples of particulate and sediment OM. Svalbard fjords, Storfjorden, Barents Sea shelf, continental slope, and Nansen Basin were characterized by different environmental settings including various sea ice conditions, bloom stage, sediment OM and particulate OM in bottom water. The highest biodiversity and biomass were found at the shelf and slope stations where intensive bloom was observed and was related to higher concentrations of fresh, high-quality OM. Low benthic infaunal diversity, abundance, and biomass were noted in fjords and deep stations where quality and quantity of OM was markedly lower. Deposit feeders were the only feeding guild sampled in the deep stations while at other stations 3-4 trophic levels were found.

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