A new look at the Lake Superior biomass size spectrum

2014 ◽  
Vol 71 (9) ◽  
pp. 1324-1333 ◽  
Author(s):  
Peder M. Yurista ◽  
Daniel L. Yule ◽  
Matt Balge ◽  
Jon D. VanAlstine ◽  
Jo A. Thompson ◽  
...  
Keyword(s):  
Size Structure ◽  
Lake Superior ◽  
Size Spectrum ◽  
Prey Fish ◽  
Size Spectra ◽  
Predator Prey ◽  
Multiple Sampling ◽  
Acoustic Surveys ◽  
Pelagic Prey ◽  
Polynomial Regressions

We synthesized data from multiple sampling programs and years to describe the Lake Superior pelagic biomass size structure. Data consisted of Coulter counts for phytoplankton, optical plankton counts for zooplankton, and acoustic surveys for pelagic prey fish. The size spectrum was stable across two time periods separated by 5 years. The primary scaling or overall slope of the normalized biomass size spectra for the combined years was −1.113, consistent with a previous estimate for Lake Superior (−1.10). Periodic dome structures within the overall biomass size structure were fit to polynomial regressions based on the observed sub-domes within the classical taxonomic positions (algae, zooplankton, and fish). This interpretation of periodic dome delineation was aligned more closely with predator–prey size relationships that exist within the zooplankton (herbivorous, predacious) and fish (planktivorous, piscivorous) taxonomic positions. Domes were spaced approximately every 3.78 log10 units along the axis and with a decreasing peak magnitude of −4.1 log10 units. The relative position of the algal and herbivorous zooplankton domes predicted well the subsequent biomass domes for larger predatory zooplankton and planktivorous prey fish.

scholarly journals Effects of fish predation on density and size spectra of prey fish communities in lakes

2016 ◽  
Vol 73 (4) ◽  
pp. 506-518 ◽  
Author(s):  
Thomas Mehner ◽  
Caroline Keeling ◽  
Matthias Emmrich ◽  
Kerstin Holmgren ◽  
Christine Argillier ◽  
...  
Keyword(s):  
Size Structure ◽  
Prey Size ◽  
Fish Communities ◽  
Fish Predation ◽  
Prey Fish ◽  
Benthivorous Fish ◽  
Size Spectra ◽  
Predator Prey ◽  
Piscivorous Fish ◽  
Predation Effects

Planktivorous and benthivorous fish have been documented to influence the density and size structure of their prey communities in lakes. We hypothesized that piscivorous fish modify their prey fish communities in the same way and sought to find evidence for such predation effects from a comparison across 356 lakes located in nine European ecoregions. We categorized individual fish as being piscivore, nonpiscivore, or prey of piscivores, depending on species and individual size. We calculated piscivore, nonpiscivore, and piscivore prey densities, respectively, and fit linear abundance size spectra (SS) on lake-specific piscivore, nonpiscivore, and piscivore-prey size distributions. Multiple linear regressions were calculated to quantify the effect of piscivore density and SS slopes on nonpiscivore and piscivore-prey densities and SS slopes by accounting for potentially confounding factors arising from lake morphometry, productivity, and local air temperature. Piscivore density correlated positively with piscivore-prey density but was uncorrelated with density of nonpiscivores. Across a subset of 76 lakes for which SS slopes of piscivores were statistically significant, SS slopes of piscivores were uncorrelated with SS slopes of either nonpiscivores or piscivore prey. However, densities of piscivores, nonpiscivores, or piscivore prey were a significant negative predictor of SS slopes of the respective groups. Our analyses suggest that direct predation effects by piscivorous fish on density and size structure of prey fish communities are weak in European lakes, likely caused by low predator–prey size ratios and the resulting size refuges for prey fish. In contrast, competition may substantially contribute to between-lake variability in fish density and size.

Shifts in plankton size spectra modulate growth and coexistence of anchovy and sardine in upwelling systems

2016 ◽  
Vol 73 (4) ◽  
pp. 611-621 ◽  
Author(s):  
T. Mariella Canales ◽  
Richard Law ◽  
Julia L. Blanchard
Keyword(s):  
Size Structure ◽  
Prey Availability ◽  
Empirical Work ◽  
Size Composition ◽  
Size Spectrum ◽  
Small Particles ◽  
Size Spectra ◽  
Factors Influencing ◽  
Spectrum Model ◽  
Model Scenarios

Fluctuations in the abundance of anchovy (Engraulis spp.) and sardine (Sardinops sagax) are widespread in marine ecosystems, but the causes still remain uncertain. Differences between the planktonic prey availability, selectivity, and predation between anchovy and sardine have been suggested as factors influencing their dynamics. Using a dynamical multispecies size-spectrum model, we explore the consequences of changes in plankton size composition, together with intraguild predation and cannibalism, on the coexistence of these species. The shift towards smaller plankton has led to a reduction in the growth rate of both species. The effect was more deleterious on anchovy growth because it is unable to filter small particles. In model scenarios that included the effects of cannibalism and predation, anchovy typically collapsed under conditions favouring smaller sized plankton. The two species coexisted under conditions of larger sized plankton, although strong predation in conjunction with weak cannibalism led to the loss of sardine. The model provides new testable predictions for the consequences of plankton size structure on anchovy and sardine fluctuations. Further empirical work is needed to test these predictions in the context of climate change.

Comparison and utility of different size-based metrics of fish communities for detecting fishery impacts

2006 ◽  
Vol 63 (4) ◽  
pp. 810-820 ◽  
Author(s):  
Daniel E Duplisea ◽  
Martin Castonguay
Keyword(s):  
Standing Stock ◽  
Fish Communities ◽  
Ecosystem Approach ◽  
Size Spectrum ◽  
Size Spectra ◽  
Predator Prey ◽  
Similar Information ◽  
Chance Events ◽  
Length Frequency Analysis ◽  
Scientific Survey

The use of fish community indicators based on size spectra has become popular in the development of an ecosystem approach to fisheries. Size spectrum theory arose from basic ecological work on energy flow, predator–prey interactions, and biomass standing stock and was later applied to fish communities as length–frequency analysis. A multitude of size spectrum indicators have resulted, but it is not clear if they all present similar information. Here we develop a simple framework describing what four size spectra indicators suggest about fish communities, their likely response to fisheries exploitation, their ecological interpretation, and some of their biases. We examined indicators for scientific survey data from six exploited North Atlantic fish communities for the information that they reveal about each community. Each indicator revealed different information and had different biases. Combining indicators for the most impacted system (owing to fisheries and environmental change), the eastern Scotian Shelf, revealed a pattern analogous to Holling's ecological cycle of exploitation, conservation, release, and reorganisation. If this analogy is generally valid, then it suggests that collapsed fish communities are more susceptible to chance events, and recovery is not directly reversible and may not be recoverable (to previous known state) at all if the system moves to an alternative cycle.

scholarly journals Fish life history dynamics: shifts in prey size structure evoke shifts in predator maturation traits

2016 ◽  
Vol 73 (4) ◽  
pp. 693-708 ◽  
Author(s):  
Brian J. Shuter ◽  
Henrique C. Giacomini ◽  
Derrick de Kerckhove ◽  
Kris Vascotto
Keyword(s):  
Life History ◽  
Lake Trout ◽  
Size Structure ◽  
Prey Size ◽  
Empirical Support ◽  
Growth Efficiency ◽  
Size Ratio ◽  
Size Spectrum ◽  
Lower Growth ◽  
Predator Prey

A bioenergetic framework is developed to predict optimal life history responses to environmentally driven changes in the rate of energy production by a predator. This framework is used to predict the responses of age at maturation, size at maturation, and asymptotic size to changes in the predator–prey size ratio. Predators feeding on relatively smaller prey (i.e., having larger predator–prey size ratios) have lower growth efficiency and are predicted as a consequence to mature earlier, at smaller sizes, and reach smaller asymptotic sizes. This prediction was tested using a 78-year time series (1936–2013) of data from a natural population of lake trout (Salvelinus namaycush) in Lake Opeongo, Algonquin Park, Ontario, Canada. A large decrease in the predator–prey size ratio for this population occurred over the period 1950–1965 when a preferred prey (cisco, Coregonus artedii) was introduced to the lake. This decrease was followed by ∼20 years of constancy in the size ratio and then 25 years of progressive increase. Lake trout life history responded plastically during both periods and consistently with our predictions. Extensive analysis of available data provided little empirical support for alternative explanations for the observed changes in lake trout size and maturity (e.g., changes in cisco and (or) lake trout density and harvest rates). The framework developed here derives plastic life history changes from fixed developmental thresholds that are based on the scaling of net production with body size and can be used to predict the shape of maturation reaction norms for the major shifts in community structure that are compactly summarized by changes in size spectrum parameters.

Size-based approaches to aquatic ecosystems and fisheries science: a symposium in honour of Rob Peters

2016 ◽  
Vol 73 (4) ◽  
pp. 471-476 ◽  
Author(s):  
Henrique C. Giacomini ◽  
Brian J. Shuter ◽  
Julia K. Baum
Keyword(s):  
Community Structure ◽  
Body Size ◽  
Empirical Studies ◽  
Ecosystem Dynamics ◽  
Future Research ◽  
Size Spectrum ◽  
Ecological Change ◽  
Size Spectra ◽  
Predator Prey ◽  
Fisheries Science

This special issue honours Rob Peters’ outstanding contributions to the field of aquatic ecology. It focuses on the size spectrum approach — in which individual organisms, rather than species, are the most basic biological unit — and highlights applications of this approach to fisheries management. The 21 papers in this issue cover three subject areas: (i) the use of size spectra to characterize variation in community structure, (ii) the development of size-based models of ecosystem dynamics to address fisheries questions, and (iii) applications of size-based theory to examine the consequences of variation in predator–prey size relationships, body size – trophic level relationships, and body size – life history relationships. The empirical studies herein demonstrate the utility of size spectra as indicators of population or community structure and for detecting impacts associated with environmental change. Future research focused on refining size-based sampling methods, standardizing metrics and analytical methods, understanding model sensitivity to the underlying assumptions, and comparative studies across ecosystems will enhance our ability to reliably interpret changes in size spectrum characteristics, thus facilitating their use as indicators of ecological change.

Size Spectrum Theory

2019 ◽  
pp. 15-37
Author(s):  
Ken H. Andersen
Keyword(s):  
Body Size ◽  
Power Law ◽  
Clearance Rate ◽  
Size Structure ◽  
Prey Size ◽  
Marine Ecosystem ◽  
Size Spectrum ◽  
Predator Prey ◽  
Predation Mortality ◽  
Size Preference

This chapter follows the size-structure of the entire marine ecosystem. It shows how the Sheldon spectrum emerges from predator–prey interactions and the limitations that physics and physiology place on individual organisms. How predator–prey interactions and physiological limitations scale with body size are the central assumptions in size spectrum theory. To that end, this chapter first defines body size and size spectrum. Next, it shows how central aspects of individual physiology scale with size: metabolism, clearance rate, and prey size preference. On that basis, it is possible to derive a power-law representation of the size spectrum by considering a balance between the needs of an organism (its metabolism) and the encountered prey, which is determined by the spectrum, the clearance rate, and the size preference. Lastly, the chapter uses the solution of the size spectrum to derive the expected size scaling of predation mortality.

Consequences of prey fish community dynamics on lake trout (Salvelinus namaycush) foraging efficiency in Lake Superior

1998 ◽  
Vol 55 (5) ◽  
pp. 1273-1284 ◽  
Author(s):  
Doran M Mason ◽  
Timothy B Johnson ◽  
James F Kitchell
Keyword(s):  
Fish Community ◽  
Community Dynamics ◽  
Lake Trout ◽  
Size Structure ◽  
Lake Superior ◽  
Salvelinus Namaycush ◽  
Foraging Efficiency ◽  
Prey Fish ◽  
Rainbow Smelt ◽  
Lake Herring

We used a size-structured model, indexed by age, that combines bioenergetics and foraging theory to evaluate the effects of prey fish community structure (species dominance, size structure, and density) on the diet and net foraging efficiency of lake trout (Salvelinus namaycush) in Lake Superior. Prey size structure was important for young lake trout but decreased in importance for older lake trout, especially with increasing prey density. The model predicted that rainbow smelt (Osmerus mordax) should dominate the diet of young lake trout due to the size-dependent capture limitations of larger prey. In contrast, lake herring (Coregonus artedi) should dominate the diet of oldest lake trout owing to a higher net energy return than rainbow smelt. Model results are consistent with age-specific diet and size-at-age of lake trout during the last 40 years. Diets of intermediate-sized lake trout do not reflect the recent resurgence of lake herring populations. Absence of a dietary switch is probably due to higher capture probability for rainbow smelt. Lake trout growth and production will likely be highest with a mixed prey species assemblage of young rainbow smelt and older lake herring.

Copepods size structure in various phases of a cold-core eddy - Normalised Abundance Size Spectra (NASS) approach.

2020 ◽  
Vol 206 ◽  
pp. 104197
Author(s):  
L. Jagadeesan ◽  
T.N.R. Srinivas ◽  
A. Surendra ◽  
G. Sampath Kumar ◽  
M.P Aswindev ◽  
...  
Keyword(s):  
Size Structure ◽  
Size Spectra ◽  
Cold Core

Using an individual-based model of fish assemblages to study the response of size spectra to changes in fishing

2004 ◽  
Vol 61 (3) ◽  
pp. 414-431 ◽  
Author(s):  
Yunne-Jai Shin ◽  
Philippe Cury
Keyword(s):  
Fish Assemblages ◽  
Prey Availability ◽  
Empirical Studies ◽  
Marine Ecosystem ◽  
Predatory Fish ◽  
Size Spectrum ◽  
Individual Based Model ◽  
Size Spectra ◽  
Predation Mortality ◽  
Body Shapes

For most fish species, strong environmental constraints imposed by living in an aquatic medium have produced converging streamlined body forms without prehensile appendices. This similarity in body shapes highlights a common predation constraint: a predatory fish must have a jaw large enough to swallow its prey. Fish diets may then reflect local prey availability and predator–prey size ratios. Based on this size-based opportunistic predation process, the multispecies individual-based model OSMOSE (Object-oriented Simulator of Marine ecOSystem Exploitation) is used to investigate to what extent the size distribution of fish communities can contribute to better our understanding of the functioning of marine food webs and the ecosystem effects of fishing. Strong similarity in shape is found between simulated size spectra and those described in empirical studies. The existence of a curvature towards small size classes is discussed in the light of the size-based predation hypothesis, which implies that smaller fish may undergo higher predation mortality. Applying linear and quadratic regressions to the simulated size spectra allows the detection of variations in fishing pressure and the proposal of different ways to quantify them. In particular, it is shown that the slope of the size spectrum decreases quasilinearly with fishing mortality and that the curvature could help to detect ecosystem overexploitation.

scholarly journals Broadening of Cloud Droplet Size Spectra by Stochastic Condensation: Effects of Mean Updraft Velocity and CCN Activation

2018 ◽  
Vol 75 (2) ◽  
pp. 451-467 ◽  
Author(s):  
Gaetano Sardina ◽  
Stéphane Poulain ◽  
Luca Brandt ◽  
Rodrigo Caballero
Keyword(s):  
Chemical Composition ◽  
Droplet Size ◽  
Isotropic Turbulence ◽  
Cloud Condensation Nuclei ◽  
Collision Probability ◽  
Droplet Radius ◽  
Droplet Growth ◽  
Size Spectrum ◽  
Similar Reduction ◽  
Size Spectra

Abstract The authors study the condensational growth of cloud droplets in homogeneous isotropic turbulence by means of a large-eddy simulation (LES) approach. The authors investigate the role of a mean updraft velocity and of the chemical composition of the cloud condensation nuclei (CCN) on droplet growth. The results show that a mean constant updraft velocity superimposed onto a turbulent field reduces the broadening of the droplet size spectra induced by the turbulent fluctuations alone. Extending the authors’ previous results regarding stochastic condensation, the authors introduce a new theoretical estimation of the droplet size spectrum broadening that accounts for this updraft velocity effect. A similar reduction of the spectra broadening is observed when the droplets reach their critical size, which depends on the chemical composition of CCN. The analysis of the square of the droplet radius distribution, proportional to the droplet surface, shows that for large particles the distribution is purely Gaussian, while it becomes strongly non-Gaussian for smaller particles, with the left tail characterized by a peak around the haze activation radius. This kind of distribution can significantly affect the later stages of the droplet growth involving turbulent collisions, since the collision probability kernel depends on the droplet size, implying the need for new specific closure models to capture this effect.

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