Regional ecosystem variability drives the relative importance of bottom-up and top-down factors for zooplankton size spectra

2007 ◽  
Vol 64 (3) ◽  
pp. 516-529 ◽  
Author(s):  
Kerri Finlay ◽  
Beatrix E Beisner ◽  
Alain Patoine ◽  
Bernadette Pinel-Alloul
Keyword(s):  
Pareto Distribution ◽  
Size Structure ◽  
Fish Predation ◽  
Top Down ◽  
Lake Productivity ◽  
Size Spectra ◽  
Bottom Up ◽  
Zooplankton Size ◽  
Fish Species Composition ◽  
Zooplankton Communities

The relative effects of top-down and bottom-up drivers of zooplankton size structure were examined in three limnologically diverse regions of Quebec, Canada. Lake productivity drove biomass of small-sized zooplankton (300–1000 µm) in the Eastern Townships and Laurentian regions, which have high total phosphorus gradients, but was not significant in the low-productivity region, Gouin. Fish species composition was found to affect biomass of large-sized (>1000 µm) zooplankton and was the primary factor affecting zooplankton size structure in the low productivity region. When size structure of the zooplankton communities were described as normalized biomass size spectra, only bottom-up factors were significant, as increasing productivity resulted in higher curve peaks and increased parabola curvature. No factors were significantly related to any parameter of the Pareto distribution to describe size spectra. Overall, bottom-up forces were stronger drivers of zooplankton size structure, particularly in regions with wide ranges in lake trophy, while fish predation was more important in regions with low productivity variability.

scholarly journals Top-down and bottom-up effects on zooplankton size distribution in a deep stratified lake

2021 ◽  
Author(s):  
Lisa-Marie Braun ◽  
Sandra Brucet ◽  
Thomas Mehner
Keyword(s):  
Size Distribution ◽  
Chlorophyll A ◽  
Total Phosphorus ◽  
Size Spectrum ◽  
Small Contribution ◽  
Size Distributions ◽  
Top Down ◽  
Size Spectra ◽  
Bottom Up ◽  
Zooplankton Size

AbstractTrophic interactions in the pelagic area of lakes and the opposing effects of fish feeding (top-down) and phytoplankton biomass (bottom-up) on zooplankton communities are central topics in limnology. We hypothesized that zooplankton size distributions should be a more sensitive approach to disentangle top-down and bottom-up effects than the commonly measured zooplankton biomass. We examined zooplankton size distributions from 148 samples collected during summer months in the upper and lower pelagic layers of a deep mesotrophic lake among 13 years of sampling. Top-down effects, namely fish size and biomass, and bottom-up effects, including water temperature and total phosphorus and chlorophyll a concentrations, were considered. To add robustness to our analyses, we expressed the zooplankton size distributions as size spectra based on log-binning, as continuous size spectra and by the size diversity, a measure that has been developed to mimic taxonomic diversity indices. Among numerous regressions tested, significant top-down or bottom-up effects could rarely been detected. Our results indicate that the overall zooplankton size distribution was not significantly affected by fish predation and lake productivity measured as total phosphorus or chlorophyll a concentration. However, we found negative correlations between fish biomass and the preferred zooplankton prey, including Bosmina longirostris, Daphnia cucullata and nauplii in the upper depth layer. However, due to their small body size, low biomass and therefore relative small contribution to the zooplankton size distribution, predation on preferred zooplankton species did not translate into a statistically significant modification of the entire size spectrum. Consequently, the size spectrum seems to be relatively robust against predation effects, but might reflect the lake-wide energy availability and transfer efficiency in the food web.

Trophic Relationships in Freshwater Pelagic Ecosystems

1986 ◽  
Vol 43 (8) ◽  
pp. 1571-1581 ◽  
Author(s):  
Donald J. McQueen ◽  
John R. Post ◽  
Edward L. Mills
Keyword(s):  
Food Web ◽  
Trophic Status ◽  
Size Structure ◽  
Trophic Relationships ◽  
Top Down ◽  
Eutrophic Lakes ◽  
Bottom Up ◽  
Coefficients Of Variation ◽  
Step Down ◽  
Pelagic Ecosystems

Relative impacts of bottom-up (producer controlled) and top-down (consumer controlled) forces on the biomass and size structure of five major components of freshwater pelagic systems (piscivores, planktivores, zooplankton, phytoplankton, and total phosphorus availability) were estimated. Predictions that emerge are (1) maximum biomass at each trophic level is controlled from below (bottom-up) by nutrient availability, (2) this bottom-up regulation is strongest at the bottom of the food web (i.e. phosphorus → phytoplankton) and weakens by a factor of 2 with each succeeding step up the food web, (3) as energy moves up a food web, the predictability of bottom-up interactions decreases, (4) near the top of the food web, top-down (predator mediated) interactions are strong and have low coefficients of variation, but weaken with every step down the food web, (5) variability around the bottom-up regressions can always be explained by top-down forces, and (6) interplay between top-down and bottom-up effects changes with the trophic status of lakes. In eutrophic lakes, top-down effects are strong for piscivore → zooplankton, weaker for planktivore → zooplankton, and have little impact for zooplankton → phytoplankton. For oligotrophic lakes, the model predicts that top-down effects are not strongly buffered, so that zooplankton → phytoplankton interactions are significant.

scholarly journals A review of bottom-up vs. top-down control of sponges on Caribbean fore-reefs: what’s old, what’s new, and future directions

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4343 ◽  
Author(s):  
Joseph R. Pawlik ◽  
Tse-Lynn Loh ◽  
Steven E. McMurray
Keyword(s):  
Community Structure ◽  
Past Research ◽  
Fish Predation ◽  
Sponge Species ◽  
Top Down ◽  
Bottom Up ◽  
Fore Reef ◽  
The Past ◽  
The Impact ◽  
Hawksbill Turtles

Interest in the ecology of sponges on coral reefs has grown in recent years with mounting evidence that sponges are becoming dominant members of reef communities, particularly in the Caribbean. New estimates of water column processing by sponge pumping activities combined with discoveries related to carbon and nutrient cycling have led to novel hypotheses about the role of sponges in reef ecosystem function. Among these developments, a debate has emerged about the relative effects of bottom-up (food availability) and top-down (predation) control on the community of sponges on Caribbean fore-reefs. In this review, we evaluate the impact of the latest findings on the debate, as well as provide new insights based on older citations. Recent studies that employed different research methods have demonstrated that dissolved organic carbon (DOC) and detritus are the principal sources of food for a growing list of sponge species, challenging the idea that the relative availability of living picoplankton is the sole proxy for sponge growth or abundance. New reports have confirmed earlier findings that reef macroalgae release labile DOC available for sponge nutrition. Evidence for top-down control of sponge community structure by fish predation is further supported by gut content studies and historical population estimates of hawksbill turtles, which likely had a much greater impact on relative sponge abundances on Caribbean reefs of the past. Implicit to investigations designed to address the bottom-up vs. top-down debate are appropriate studies of Caribbean fore-reef environments, where benthic communities are relatively homogeneous and terrestrial influences and abiotic effects are minimized. One recent study designed to test both aspects of the debate did so using experiments conducted entirely in shallow lagoonal habitats dominated by mangroves and seagrass beds. The top-down results from this study are reinterpreted as supporting past research demonstrating predator preferences for sponge species that are abundant in these lagoonal habitats, but grazed away in fore-reef habitats. We conclude that sponge communities on Caribbean fore-reefs of the past and present are largely structured by predation, and offer new directions for research, such as determining the environmental conditions under which sponges may be food-limited (e.g., deep sea, lagoonal habitats) and monitoring changes in sponge community structure as populations of hawksbill turtles rebound.

scholarly journals Climate-induced changes in bottom-up and top-down processes independently alter a marine ecosystem

2012 ◽  
Vol 367 (1605) ◽  
pp. 2962-2970 ◽  
Author(s):  
Malte Jochum ◽  
Florian D. Schneider ◽  
Tasman P. Crowe ◽  
Ulrich Brose ◽  
Eoin J. O'Gorman
Keyword(s):  
Body Size ◽  
Body Mass ◽  
Nutrient Enrichment ◽  
Size Structure ◽  
Marine Ecosystem ◽  
Shore Crab ◽  
Top Predator ◽  
Top Down ◽  
Microalgal Biomass ◽  
Bottom Up

Climate change has complex structural impacts on coastal ecosystems. Global warming is linked to a widespread decline in body size, whereas increased flood frequency can amplify nutrient enrichment through enhanced run-off. Altered population body-size structure represents a disruption in top-down control, whereas eutrophication embodies a change in bottom-up forcing. These processes are typically studied in isolation and little is known about their potential interactive effects. Here, we present the results of an in situ experiment examining the combined effects of top-down and bottom-up forces on the structure of a coastal marine community. Reduced average body mass of the top predator (the shore crab, Carcinus maenas ) and nutrient enrichment combined additively to alter mean community body mass. Nutrient enrichment increased species richness and overall density of organisms. Reduced top-predator body mass increased community biomass. Additionally, we found evidence for an allometrically induced trophic cascade. Here, the reduction in top-predator body mass enabled greater biomass of intermediate fish predators within the mesocosms. This, in turn, suppressed key micrograzers, which led to an overall increase in microalgal biomass. This response highlights the possibility for climate-induced trophic cascades, driven by altered size structure of populations, rather than species extinction.

scholarly journals Response of Zooplankton Size Structure to Multiple Stressors in Urban Lakes

Water ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2305
Author(s):  
Reliana Lumban Toruan ◽  
Liah X. Coggins ◽  
Anas Ghadouani
Keyword(s):  
Body Size ◽  
Environmental Variables ◽  
Size Structure ◽  
Negative Slope ◽  
Total Biomass ◽  
Size Spectra ◽  
Urban Lakes ◽  
Chl A ◽  
Zooplankton Size ◽  
Density And Biomass

Urban lakes are important environmental assets that contribute significant ecosystem services in urbanised areas around the world. Consequently, urban lakes are more exposed to anthropogenic pressures. Zooplankton communities play a central role in lake processes and, as such, are very sensitive to the impacts of human activities both through in-lake and catchment processes. Understanding their ecological function in urban lakes and how they respond to urbanisation is essential for environmental sustainability. In this study, we investigated the reliability of zooplankton size structure as indicators of anthropogenic stressors in urban lakes. We examined the relationship between environmental variables and zooplankton community size spectra derived as mean body size, density, and biomass. Our study showed that the overall mean body size was within the small size group ranged from 416 to 735 µm equivalent spherical diameter (ESD). Despite no significant difference in total zooplankton density between lakes, there was variability in the total density of the five different size classes. Total biomass was characterised by a significant proportion of size >750 µm. As the specific parameter of normalised biomass size spectra (NBSS), the slopes of the NBSS varied from moderate (−0.83 to −1.04) for a community with higher biomass of the larger size zooplankton to steeper slopes (from −1.15 to −1.49) for a community with higher biomass of smaller size. The environmental variables, represented by total phosphorus (TP) and chlorophyll a (chl-a), had a strong effect on zooplankton biomass and NBSS, where TP and chl-a were significantly correlated with the increase of total biomass and corresponded well with a less negative slope. Our results indicated that the community metric was sensitive to nutrient input and that size-based metrics have the potential to serve as key indicators for the management of urban lakes.

scholarly journals The Impact of Fish Predation and Cyanobacteria on Zooplankton Size Structure in 96 Subtropical Lakes

PLoS ONE ◽  
2013 ◽  
Vol 8 (10) ◽  
pp. e76378 ◽  
Author(s):  
Jing Zhang ◽  
Ping Xie ◽  
Min Tao ◽  
Longgen Guo ◽  
Jun Chen ◽  
...  
Keyword(s):  
Size Structure ◽  
Fish Predation ◽  
Subtropical Lakes ◽  
Zooplankton Size ◽  
The Impact

scholarly journals Density-dependent effects as key drivers of intraspecific size structure of six abundant fish species in lakes across Europe

2016 ◽  
Vol 73 (4) ◽  
pp. 519-534 ◽  
Author(s):  
Ignasi Arranz ◽  
Thomas Mehner ◽  
Lluís Benejam ◽  
Christine Argillier ◽  
Kerstin Holmgren ◽  
...  
Keyword(s):  
Body Size ◽  
Density Dependence ◽  
Fish Species ◽  
Size Structure ◽  
Catch Per Unit Effort ◽  
Lake Productivity ◽  
Size Spectra ◽  
Fish Size ◽  
Density Dependent ◽  
Size Diversity

We studied fish size structure by using mean size, size diversity, and the slope of linear size spectra of six common European fish species along large-scale environmental gradients. We further analyzed the response of these three size metrics to environmental variables and to density-dependent effects, i.e., relative estimates of abundance (catch per unit effort, CPUE). We found differences in the strength of main predictors of size structure between the six species, but the direction of the response was relatively similar and consistent for most of the size metrics. Mean body size was negatively related to temperature for perch (Perca fluviatilis), roach (Rutilus rutilus), and ruffe (Gymnocephalus cernuus). Lake productivity (expressed as total phosphorus concentration) and lake depth were also predictors of size structure for four of six species. Moreover, we found a strong density dependence of size structure for all species, resulting in lower mean body size and size diversity and steeper size spectra slopes when density dependence increases. This suggests that density dependence is a key driver of fish size structure.

scholarly journals Abundance and size structure of planktonic protist communities in a Neotropical floodplain: effects of top-down and bottom-up controls

2017 ◽  
Vol 29 (0) ◽  
Author(s):  
Bianca Ramos de Meira ◽  
Fernando Miranda Lansac-Tôha ◽  
Bianca Trevizan Segovia ◽  
Felipe Rafael de Oliveira ◽  
Paulo Roberto Bressan Buosi ◽  
...  
Keyword(s):  
Heterotrophic Bacteria ◽  
Size Structure ◽  
Information Criterion ◽  
Heterotrophic Flagellates ◽  
Control Mechanisms ◽  
Linear Regression Models ◽  
Top Down ◽  
Bottom Up ◽  
Upper Paraná River Floodplain ◽  
Predation Effects

Abstract: Aim: We aimed to assess the influence of bottom-up and top-down control mechanisms on the abundance and size structure of protist communities (heterotrophic flagellates and ciliates). We formulated the following hypothesis: bottom-up control mechanisms, related to the availability of resources in the environment, are responsible for structuring the abundance of these communities, whereas top-down control mechanisms, related to predation effects, determine the size pattern of these organisms. Methods Samples for planktonic organisms were taken in 20 shallow lakes belonging to the upper Paraná River floodplain. We evaluated linear regression models to select the best model which predicts the patterns observed according to Akaike Information Criterion. Results The best models selected to explain the abundance of heterotrophic flagellates included negative relations with picophytoplankton abundance and positive with rotifers abundance, while for their size structure, negative relationships were found with heterotrophic bacteria, ciliates and rotifers biovolumes. In relation to the ciliates, their abundances were positively related to the rotifers and picophytoplankton abundances and negatively with the heterotrophic bacteria abundance. On the other hand, for the size structure, the best models selected strong negative relations with the microcrustaceans biovolumes, in addition to relations with the different fractions of the phytoplankton. Conclusion For both flagellates and ciliates, their abundance is being mainly regulated by a bottom up control mechanism, whereas for the size structure the results showed that both food resources and predators were important, indicating that bottom-up and top-down mechanisms act simultaneously in determining the size of these microorganisms.

scholarly journals Spring-time zooplankton size structure over the continental shelf of the Bay of Biscay

2013 ◽  
Vol 10 (6) ◽  
pp. 2207-2254 ◽  
Author(s):  
P. Vandromme ◽  
E. Nogueira ◽  
M. Huret ◽  
Á Lopez-Urrutia ◽  
G. González-Nuevo González ◽  
...  
Keyword(s):  
Size Structure ◽  
Mesh Size ◽  
Trophic Levels ◽  
Equivalent Diameter ◽  
Special Focus ◽  
Bay Of Biscay ◽  
Data Set ◽  
Size Spectra ◽  
Explanatory Variables ◽  
Zooplankton Size

Abstract. Linking lower to higher trophic levels requires a special focus on the pivotal role played by mid-trophic levels, i.e. the zooplankton. One of the most relevant information on zooplankton in term of fluxes of matter lies in its size structure. We present here an extensive dataset of size measurements covering part of the western European shelf and slope, from the Galician coast to the Ushant front, during springs from 2005 to 2012. Zooplankton size spectra were estimated using both measurements carried out in situ by the Laser-Optical Plankton Counter (LOPC, 816 records) and WP2 net (200 μm mesh size) samples scanned following the ZooScan methodology and image analysis (a total of 89 samples were analyzed). The LOPC counts and sizes all particles in the range 100 to 2000 μm of spherical equivalent diameter (ESD) whereas the WP2/ZooScan allows the counting, sizing and identification of zooplankton from ~400 μm ESD. The difference between the LOPC (all particles) and the WP2/ZooScan (zooplankton only) is assumed to provide the size distribution of non-living particles whose descriptors are further related to a set of explanatory variables (including physical, biological and geographic descriptors). A statistical correction based on these explanatory variables is then applied to LOPC measurements to removed the part due to non-living particles and estimate zooplankton size spectra. This extensive data set provides a new look at regional and inter-annual variability of the pelagic ecosystem of the Bay of Biscay.

scholarly journals Bottom-up and top-down effects of temperature on body growth, population size spectra and yield in a size-structured food web

2021 ◽  
Author(s):  
Max Lindmark ◽  
Asta Audzijonyte ◽  
Julia Blanchard ◽  
Anna Gårdmark
Keyword(s):  
Food Web ◽  
Growth Rates ◽  
Temperature Effects ◽  
Size Structure ◽  
Metabolic Effects ◽  
Young Fish ◽  
Top Down ◽  
Bottom Up ◽  
Effects Of Temperature ◽  
Size At Age

AbstractResolving the combined effect of climate warming and exploitation in a food web context is key for predicting future biomass production, size-structure, and potential yields of marine fishes. Previous studies based on mechanistic size-based food web models have found that bottom-up processes are important drivers of size-structure and fisheries yield in changing climates. However, we know less about the joint effects of ‘bottom-up’ and ‘top-down’ effects of temperature: how do temperature effects propagate from individual-level physiology through food webs and alter the size-structure of exploited species in a community? Here we assess how a species-resolved size-based food web is affected by warming through both these pathways, and by exploitation. We parameterize a dynamic size spectrum food web model inspired by the offshore Baltic Sea food web, and investigate how individual growth rates, size-structure, relative abundances of species and yields are affected by warming. The magnitude of warming is based on projections by the regional coupled model system RCA4-NEMO and the RCP 8.5 emission scenario, and we evaluate different scenarios of temperature dependence on fish physiology and resource productivity. When accounting for temperature-effects on physiology in addition to on basal productivity, projected size-at-age in 2050 increases on average for all fish species, mainly for young fish, compared to scenarios without warming. In contrast, size-at-age decreases when temperature affects resource dynamics only, and the decline is largest for young fish. Faster growth rates due to warming, however, do not always translate to larger yields, as lower resource carrying capacities with increasing temperature tend to result in declines in the abundance of larger fish and hence spawning stock biomass – the part of the population exposed to fishing. These results show that to understand how global warming impacts the size structure of fish communities, both direct metabolic effects and indirect effects of temperature via basal resources must be accounted for.

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