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.

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.

Using food web model results to inform stock assessment estimates of mortality and production for ecosystem-based fisheries management

2010 ◽  
Vol 67 (9) ◽  
pp. 1490-1506 ◽  
Author(s):  
Sarah K. Gaichas ◽  
Kerim Y. Aydin ◽  
Robert C. Francis
Keyword(s):  
Food Web ◽  
Fisheries Management ◽  
Prey Availability ◽  
Stock Assessment ◽  
Marine Ecosystem ◽  
Single Species ◽  
Balance Model ◽  
Fishing Mortality ◽  
Important Species ◽  
Predation Mortality

Examining food web relationships for commercially important species enhances fisheries management by identifying sources of variability in mortality and production that are not included in standard single-species stock assessments. We use a static mass-balance model to evaluate relationships between species in a large marine ecosystem, the coastal Gulf of Alaska, USA. We focus on food web relationships for four case-study species: Pacific halibut ( Hippoglossus stenolepis ), longnose skate ( Raja rhina ), walleye pollock ( Theragra chalcogramma ), and squids (order Teuthoidea). For each, we present the species’ position within the food web, evaluate fishing mortality relative to predation mortality, and evaluate diet compositions. We find that high trophic level (TL) species, whether commercially valuable (halibut) or incidentally caught (skates), have mortality patterns consistent with single-species assessment assumptions, where fishing mortality dominates natural mortality. However, assessments for commercially valuable (pollock) or incidentally caught (squids) mid-TL species can be enhanced by including food web derived predation information because fishing mortality is small compared with high and variable predation mortality. Finally, we outline food web relationships that suggest how production of species may change with diet composition or prey availability.

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.

scholarly journals Relationships between water transparency and abundance of Cynodontidae species in the Bananal floodplain, Mato Grosso, Brazil

2009 ◽  
Vol 7 (2) ◽  
pp. 251-256 ◽  
Author(s):  
Cesar Enrique de Melo ◽  
Jane Dilvana Lima ◽  
Eliete Francisca da Silva
Keyword(s):  
Fish Assemblages ◽  
Water Transparency ◽  
Predatory Fish ◽  
Mato Grosso ◽  
Central Brazil ◽  
Fish Group ◽  
Species Specific ◽  
Abundance And Distribution ◽  
Number Of Individuals ◽  
Habitat Affinities

The Cerrado in the Central Brazil is currently one of the most threatened ecosystems in the world. As a result, the aquatic habitats in this biome also undergo great impacts. Alterations related to land-use change increase sediment loadings in rivers, streams and lakes, resulting in sedimentation and decrease in water transparency. Water transparency determines underwater visibility conditions, and as a consequence fish assemblages respond to spatial and temporal changes in this variable. This work aimed to examine the influence of transparency on the abundance and distribution of Cynodontidae species, a visually oriented predatory fish group. Fish sampling was conducted in 15 sites located between Mortes and Araguaia rivers in the Bananal floodplain, Mato Grosso State. Regression analysis between relative abundance of Cynodontidae (in number of individuals and biomass) and water transparency showed a positive and highly significant correlation, indicating that this group shows species-specific habitat affinities for clearer waters. These results suggest that the increase in water turbidity in this region can affect the patterns of abundance and distribution of the Cynodontidae species, as well as other visually oriented fishes.

scholarly journals Risk Assessment for Key Socio-Economic and Ecological Species in a Sub-Arctic Marine Ecosystem Under Combined Ocean Acidification and Warming

Ecosystems ◽  
2021 ◽  
Author(s):  
Maartje Oostdijk ◽  
Erla Sturludóttir ◽  
Maria J. Santos
Keyword(s):  
Ocean Acidification ◽  
Atlantic Cod ◽  
Marine Ecosystem ◽  
Keystone Species ◽  
Ecosystem Model ◽  
The Arctic ◽  
Predatory Fish ◽  
Important Species ◽  
Cascading Effects ◽  
Icelandic Waters

AbstractThe Arctic may be particularly vulnerable to the consequences of both ocean acidification (OA) and global warming, given the faster pace of these processes in comparison with global average speeds. Here, we use the Atlantis ecosystem model to assess how the trophic network of marine fishes and invertebrates in the Icelandic waters is responding to the combined pressures of OA and warming. We develop an approach where we first identify species by their economic (catch value), social (number of participants in fisheries), or ecological (keystone species) importance. We then use literature-determined ranges of sensitivity to OA and warming for different species and functional groups in the Icelandic waters to parametrize model runs for different scenarios of warming and OA. We found divergent species responses to warming and acidification levels; (mainly) planktonic groups and forage fish benefited while (mainly) benthic groups and predatory fish decreased under warming and acidification scenarios. Assuming conservative harvest rates for the largest catch-value species, Atlantic cod, we see that the population is projected to remain stable under even the harshest acidification and warming scenario. Further, for the scenarios where the model projects reductions in biomass of Atlantic cod, other species in the ecosystem increase, likely due to a reduction in competition and predation. These results highlight the interdependencies of multiple global change drivers and their cascading effects on trophic organization, and the continued high abundance of an important species from a socio-economic perspective in the Icelandic fisheries.

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.

scholarly journals Catch-per-unit-effort and size spectra of lake fish assemblages reflect underlying patterns in ecological conditions and anthropogenic activities across regional and local scales

2016 ◽  
Vol 73 (4) ◽  
pp. 535-546 ◽  
Author(s):  
Cindy Chu ◽  
Nigel P. Lester ◽  
Henrique C. Giacomini ◽  
Brian J. Shuter ◽  
Donald A. Jackson
Keyword(s):  
Body Size ◽  
Fish Assemblages ◽  
Anthropogenic Activities ◽  
Ecological Indicators ◽  
Size Spectrum ◽  
Catch Per Unit Effort ◽  
Ecological Processes ◽  
Boosted Regression Tree ◽  
Unit Effort ◽  
Lake Fish

Across broad geographic scales, ecological indicators for fish assemblages should represent causal ecological processes, be sensitive enough to show patterns across the landscape, and reflect underlying biotic or abiotic conditions that influence those patterns. We assessed the responses of commonly applied ecological indicators for lake fish assemblages (mean body size, catch-per-unit-effort (CPUE), and normalized length size spectrum (NLSS) slope) to regional (climate, water chemistry, and watershed stress due to human activities) and local (lake morphometry, water quality, and angling pressure) ecological and anthropogenic variables. The indicators were estimated using fish assemblage catch data acquired via a standardized gillnetting protocol implemented within 693 lakes in Ontario, Canada. To our knowledge, our study is the first size-based or catch-based indicator evaluation to include detailed observations of angling pressure on hundreds of inland lakes. Boosted regression tree models showed that CPUE of large-bodied organisms and NLSS slope best described underlying patterns in the regional and local variables. Models developed with a mix of regional and local variables performed better than models developed with regional or local variables alone. The relative influences of the variables and responses varied among indicators, but in general, ecological variables had greater influence on the indicators than anthropogenic variables. These results emphasize the complex and multiscaled nature of factors and ecological processes affecting body size, habitat-community production, and trophic dynamics in lake fish assemblages.

A functional size-spectrum model of the global marine ecosystem that resolves zooplankton composition

2020 ◽  
Vol 435 ◽  
pp. 109265
Author(s):  
Ryan F. Heneghan ◽  
Jason D. Everett ◽  
Patrick Sykes ◽  
Sonia D. Batten ◽  
Martin Edwards ◽  
...  
Keyword(s):  
Marine Ecosystem ◽  
Size Spectrum ◽  
Spectrum Model ◽  
Functional Size

Species body size distribution patterns of marine benthic macrofauna assemblages from contrasting sediment types

1999 ◽  
Vol 79 (5) ◽  
pp. 793-801 ◽  
Author(s):  
David M. Parry ◽  
Michael A. Kendall ◽  
Ashley A. Rowden ◽  
Stephen Widdicombe
Keyword(s):  
Body Size ◽  
Size Distribution ◽  
Species Turnover ◽  
Distribution Patterns ◽  
Benthic Macrofauna ◽  
Size Spectrum ◽  
Size Spectra ◽  
Β Diversity ◽  
Sediment Types ◽  
Geometric Size

Species body size spectra have been constructed for macrofauna assemblages from four sites with contrasting sediment granulometry and heterogeneity in and around Plymouth Sound. The number of species and species turnover (β diversity) were higher on coarse sediment. While the fauna were distinct between sites, the median geometric size-class was conservative (class 14; 0.153–0.305 mg dry blotted weight). Only one site had significantly lower heterogeneity within the species size spectrum, yet this was the most heterogeneous sediment. As such, we were unable to reject the null hypothesis that species body size distribution patterns are conservative despite differences in sediment granulometry and heterogeneity.

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