scholarly journals Systematic variation in food web body-size structure linked to external subsidies

2021 ◽  
Vol 17 (3) ◽  
Author(s):  
Daniel M. Perkins ◽  
Isabelle Durance ◽  
Michelle Jackson ◽  
J. Iwan Jones ◽  
Rasmus B. Lauridsen ◽  
...  
Keyword(s):  
Food Webs ◽  
Size Structure ◽  
General Assumption ◽  
Community Size ◽  
Metabolic Scaling ◽  
Terrestrial Invertebrates ◽  
Natural Systems ◽  
Size Classes ◽  
Linear Relationships ◽  
The Web

The relationship between body mass (M) and size class abundance (N) depicts patterns of community structure and energy flow through food webs. While the general assumption is that M and N scale linearly (on log–log axes), nonlinearity is regularly observed in natural systems, and is theorized to be driven by nonlinear scaling of trophic level (TL) with M resulting in the rapid transfer of energy to consumers in certain size classes. We tested this hypothesis with data from 31 stream food webs. We predicted that allochthonous subsidies higher in the web results in nonlinear M–TL relationships and systematic abundance peaks in macroinvertebrate and fish size classes (latter containing salmonids), that exploit terrestrial plant material and terrestrial invertebrates, respectively. Indeed, both M–N and M–TL significantly deviated from linear relationships and the observed curvature in M–TL scaling was inversely related to that observed in M–N relationships. Systemic peaks in M–N, and troughs in M–TL occurred in size classes dominated by generalist invertebrates, and brown trout. Our study reveals how allochthonous resources entering high in the web systematically shape community size structure and demonstrates the relevance of a generalized metabolic scaling model for understanding patterns of energy transfer in energetically ‘open’ food webs.

scholarly journals Trophic roles determine coral reef fish community size structure

2016 ◽  
Vol 73 (4) ◽  
pp. 496-505 ◽  
Author(s):  
James P.W. Robinson ◽  
Julia K. Baum
Keyword(s):  
Body Size ◽  
Coral Reef ◽  
Food Webs ◽  
Reef Fish ◽  
Coral Reef Fish ◽  
Census Data ◽  
Size Structure ◽  
Trophic Position ◽  
Great Promise ◽  
Metabolic Scaling

Relationships between abundance – body size and trophic position – body size can reveal size structuring in food webs and test ecological theory. Although there is considerable evidence of size structuring in temperate aquatic food webs, little is known about the structure of tropical coral reef food webs. Here, we use underwater visual-census data and nitrogen stable isotope analysis to test if coral reef fish communities (i) are size structured and (ii) follow metabolic scaling rules. After examining individuals from over 160 species spanning four orders of magnitude in body size, we show that abundance scaled negatively with body size and, as predicted, individuals sharing energy through predation (carnivorous fishes) scaled more steeply than those individuals sharing a common energy source (herbivorous fishes). Estimated size spectra were, however, shallower than predicted by metabolic theory. Trophic position scaled positively with body size across species and across individuals, providing novel evidence of size structuring in a diverse tropical food web. Size-based approaches hold great promise for integrating the complexities of food webs into simple quantitative measures, thus providing new insights into the structure and function of aquatic ecosystems.

Size Structure of the Plankton Community Along the Trophic Gradient of Lake Memphremagog

1983 ◽  
Vol 40 (10) ◽  
pp. 1770-1778 ◽  
Author(s):  
Robert Henry Peters
Keyword(s):  
Trophic State ◽  
Size Structure ◽  
Geometric Mean ◽  
Mesh Size ◽  
Particulate Phosphorus ◽  
Phosphorus Concentration ◽  
Community Size ◽  
Millipore Filter ◽  
Size Classes ◽  
Filter Size

The size distribution of epilimnetic plankton at four sites of differing trophic state was examined from May 1977 to May 1978 to examine the applicability to lakes of Sheldon's hypothesis that logarithmically ordered size classes contain approximately constant concentrations of biomass. The plankton was sized by serial filtration through a series of screens of mesh size 102, 75, 55, 35, 20, and 10 μm and a 0.45-μm Millipore filter. Biomass in each fraction was measured as particulate phosphorus concentration. I tested the hypothesis by examining the fit of regressions of particulate P concentration in each sequential fraction against the logarithm of the geometric mean of the meshes used to delimit that fraction. Sheldon's hypothesis leads one to expect a linear relationship. In most cases this was found but exceptions were common, and some size classes contained significantly more or less P than the linear model (Sheldon's hypothesis) would suggest. Comparison of the amount of P in the size classes I studied with previous estimates of the biomass of zooplankton and fish suggest that larger organisms may also fit the relation. The slope and intercept of these regressions between biomass and filter size increase with lake trophic state. This may allow an approximate prediction of community size structure in other lakes based on measured or predicted concentrations of total phosphorus.

scholarly journals Quantifying heterogeneous responses of fish community size structure using novel combined statistical techniques

2016 ◽  
Vol 22 (5) ◽  
pp. 1755-1768 ◽  
Author(s):  
Abigail M. Marshall ◽  
Grant R. Bigg ◽  
Sonja M. van Leeuwen ◽  
John K. Pinnegar ◽  
Hua-Liang Wei ◽  
...  
Keyword(s):  
Fish Community ◽  
Size Structure ◽  
Statistical Techniques ◽  
Community Size

scholarly journals Redundancy in metrics describing the composition, structure, and functioning of the North Sea demersal fish community

2012 ◽  
Vol 69 (1) ◽  
pp. 8-22 ◽  
Author(s):  
Simon P. R. Greenstreet ◽  
Helen M. Fraser ◽  
Stuart I. Rogers ◽  
Verena M. Trenkel ◽  
Stephen D. Simpson ◽  
...  
Keyword(s):  
North Sea ◽  
Fish Community ◽  
Size Structure ◽  
Demersal Fish ◽  
Community Size ◽  
The North ◽  
Management Objectives ◽  
The North Sea ◽  
Composition Structure ◽  
And Function

Abstract Greenstreet, S. P. R., Fraser, H. M., Rogers, S. I., Trenkel, V. M., Simpson, S. D., and Pinnegar, J. K. 2012. Redundancy in metrics describing the composition, structure, and functioning of the North Sea demersal fish community. – ICES Journal of Marine Science, 69: 8–22. Broader ecosystem management objectives for North Sea demersal fish currently focus on restoring community size structure. However, most policy drivers explicitly concentrate on restoring and conserving biodiversity, and it has not yet been established that simply restoring demersal fish size composition will be sufficient to reverse declines in biodiversity and ensure a generally healthy community. If different aspects of community composition, structure, and function vary independently, then to monitor all aspects of community general health will require application of a suite of metrics. This assumes low redundancy among the metrics used in any such suite and implies that addressing biodiversity issues specifically will require explicit management objectives for particular biodiversity metrics. This issue of metric redundancy is addressed, and 15 metrics covering five main attributes of community composition, structure, and function are applied to groundfish survey data. Factor analysis suggested a new interpretation of the metric information and indicated that a minimum suite of seven metrics was necessary to ensure that all changes in the general health of the North Sea demersal fish community were monitored properly. Covariance among size-based and species-diversity metrics was low, implying that restoration of community size structure would not necessarily reverse declines in species diversity.

scholarly journals SIZE STRUCTURE OF PHYTOPOPULATIONS AND ITS QUANTITATIVE EVALUATION

2016 ◽  
Vol 1 ◽  
pp. 9-15
Author(s):  
Victoria Skliar ◽  
Maryna Sherstuk
Keyword(s):  
Pinus Sylvestris ◽  
Quantitative Evaluation ◽  
Size Structure ◽  
Size Classes ◽  
Ledum Palustre ◽  
Forest Phytocenoses ◽  
Index Index ◽  
High Level ◽  
Original Approach

There was elucidated the original approach to the evaluation of phytopopulation size structure. For its characteristics it was offered to use the special index - index diversity of size structure (ІDSS). There are presented methods and algorithm of its determination. There was demonstrated that index diversity of size structure can be used at populational studies of species that belong to the different living forms. Especially phanerophytes (Pinus sylvestris) and hamephytes (Ledum palustre). As to Pinus sylvestris and Ledum palustre with help of index diversity of size structure was objectively proved that its cohorts and ontogenetic groups that growth in composition of forest phytocenoses typical for Ukrainian Polissya are not characterized with high level diversity of size structure. The value of index diversity of size structure is mainly less than 20 %. In phytopopulation the specific and phytocenotic peculiarity is demonstrated by diversity of size structure and also by representation of plants of certain size classes.

Effect of phytoplankton community size structure on remote-sensing reflectance and chlorophyll a products

2020 ◽  
Vol 211 ◽  
pp. 103400 ◽  
Author(s):  
Monika Soja-Woźniak ◽  
Leonardo Laiolo ◽  
Mark E. Baird ◽  
Richard Matear ◽  
Lesley Clementson ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Chlorophyll A ◽  
Phytoplankton Community ◽  
Size Structure ◽  
Community Size ◽  
Remote Sensing Reflectance

Global patterns in phytoplankton biomass and community size structure in relation to macronutrients in the open ocean

2018 ◽  
Vol 63 (3) ◽  
pp. 1298-1312 ◽  
Author(s):  
Erik Askov Mousing ◽  
Katherine Richardson ◽  
Marianne Ellegaard
Keyword(s):  
Phytoplankton Biomass ◽  
Size Structure ◽  
Open Ocean ◽  
Community Size ◽  
Global Patterns

scholarly journals Linking community size structure and ecosystem functioning using metabolic theory

2012 ◽  
Vol 367 (1605) ◽  
pp. 2998-3007 ◽  
Author(s):  
Gabriel Yvon-Durocher ◽  
Andrew P. Allen
Keyword(s):  
Ecosystem Functioning ◽  
Size Structure ◽  
Ecosystem Respiration ◽  
Gross Primary Production ◽  
Research Question ◽  
Biogeochemical Cycles ◽  
Ecosystem Functions ◽  
Central Research ◽  
Metabolic Theory ◽  
Community Size

Understanding how biogeochemical cycles relate to the structure of ecological communities is a central research question in ecology. Here we approach this problem by focusing on body size, which is an easily measured species trait that has a pervasive influence on multiple aspects of community structure and ecosystem functioning. We test the predictions of a model derived from metabolic theory using data on ecosystem metabolism and community size structure. These data were collected as part of an aquatic mesocosm experiment that was designed to simulate future environmental warming. Our analyses demonstrate significant linkages between community size structure and ecosystem functioning, and the effects of warming on these links. Specifically, we show that carbon fluxes were significantly influenced by seasonal variation in temperature, and yielded activation energies remarkably similar to those predicted based on the temperature dependencies of individual-level photosynthesis and respiration. We also show that community size structure significantly influenced fluxes of ecosystem respiration and gross primary production, particularly at the annual time-scale. Assessing size structure and the factors that control it, both empirically and theoretically, therefore promises to aid in understanding links between individual organisms and biogeochemical cycles, and in predicting the responses of key ecosystem functions to future environmental change.

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