Climate change alters fish community size-structure, requiring adaptive policy targets

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.

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Potential impacts of climate change on Northeast Pacific marine foodwebs and fisheries

ICES Journal of Marine Science ◽

10.1093/icesjms/fsr043 ◽

2011 ◽

Vol 68 (6) ◽

pp. 1217-1229 ◽

Cited By ~ 103

Author(s):

C. H. Ainsworth ◽

J. F. Samhouri ◽

D. S. Busch ◽

W. W. L. Cheung ◽

J. Dunne ◽

...

Keyword(s):

Climate Change ◽

Functional Groups ◽

Size Structure ◽

Zooplankton Community ◽

Cumulative Effects ◽

Total Biomass ◽

Community Size ◽

Climate Effects ◽

Northeast Pacific ◽

Impacts Of Climate Change

Abstract Ainsworth, C. H., Samhouri, J. F., Busch, D. S., Cheung, W. W. L., Dunne, J., and Okey, T. A. 2011. Potential impacts of climate change on Northeast Pacific marine foodwebs and fisheries. – ICES Journal of Marine Science, 68: 1217–1229. Although there has been considerable research on the impacts of individual changes in water temperature, carbonate chemistry, and other variables on species, cumulative impacts of these effects have rarely been studied. Here, we simulate changes in (i) primary productivity, (ii) species range shifts, (iii) zooplankton community size structure, (iv) ocean acidification, and (v) ocean deoxygenation both individually and together using five Ecopath with Ecosim models of the northeast Pacific Ocean. We used a standardized method to represent climate effects that relied on time-series forcing functions: annual multipliers of species productivity. We focused on changes in fisheries landings, biomass, and ecosystem characteristics (diversity and trophic indices). Fisheries landings generally declined in response to cumulative effects and often to a greater degree than would have been predicted based on individual climate effects, indicating possible synergies. Total biomass of fished and unfished functional groups displayed a decline, though unfished groups were affected less negatively. Some functional groups (e.g. pelagic and demersal invertebrates) were predicted to respond favourably under cumulative effects in some regions. The challenge of predicting climate change impacts must be met if we are to adapt and manage rapidly changing marine ecosystems in the 21st century.

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Novel communities from climate change

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2012.0238 ◽

2012 ◽

Vol 367 (1605) ◽

pp. 2913-2922 ◽

Cited By ~ 106

Author(s):

Miguel Lurgi ◽

Bernat C. López ◽

José M. Montoya

Keyword(s):

Climate Change ◽

Species Interactions ◽

Community Dynamics ◽

Size Structure ◽

Species Traits ◽

Ecological Specialization ◽

Community Size ◽

Interacting Species ◽

Distribution Ranges ◽

Body Sizes

Climate change is generating novel communities composed of new combinations of species. These result from different degrees of species adaptations to changing biotic and abiotic conditions, and from differential range shifts of species. To determine whether the responses of organisms are determined by particular species traits and how species interactions and community dynamics are likely to be disrupted is a challenge. Here, we focus on two key traits: body size and ecological specialization. We present theoretical expectations and empirical evidence on how climate change affects these traits within communities. We then explore how these traits predispose species to shift or expand their distribution ranges, and associated changes on community size structure, food web organization and dynamics. We identify three major broad changes: (i) Shift in the distribution of body sizes towards smaller sizes, (ii) dominance of generalized interactions and the loss of specialized interactions, and (iii) changes in the balance of strong and weak interaction strengths in the short term. We finally identify two major uncertainties: (i) whether large-bodied species tend to preferentially shift their ranges more than small-bodied ones, and (ii) how interaction strengths will change in the long term and in the case of newly interacting species.

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Climate change impacts on body size and food web structure on mountain ecosystems

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2012.0239 ◽

2012 ◽

Vol 367 (1605) ◽

pp. 3050-3057 ◽

Cited By ~ 45

Author(s):

Miguel Lurgi ◽

Bernat C. López ◽

José M. Montoya

Keyword(s):

Climate Change ◽

Food Web ◽

Size Structure ◽

Trophic Position ◽

Climate Change Impacts ◽

Taxonomic Composition ◽

Climatic Conditions ◽

Community Size ◽

Food Web Structure ◽

Elevation Range

The current distribution of climatic conditions will be rearranged on the globe. To survive, species will have to keep pace with climates as they move. Mountains are among the most affected regions owing to both climate and land-use change. Here, we explore the effects of climate change in the vertebrate food web of the Pyrenees. We investigate elevation range expansions between two time-periods illustrative of warming conditions, to assess: (i) the taxonomic composition of range expanders; (ii) changes in food web properties such as the distribution of links per species and community size-structure; and (iii) what are the specific traits of range expanders that set them apart from the other species in the community—in particular, body mass, diet generalism, vulnerability and trophic position within the food web. We found an upward expansion of species at all elevations, which was not even for all taxonomic groups and trophic positions. At low and intermediate elevations, predator : prey mass ratios were significantly reduced. Expanders were larger, had fewer predators and were, in general, more specialists. Our study shows that elevation range expansions as climate warms have important and predictable impacts on the structure and size distribution of food webs across space.

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Fish community size structure of small lakes: the role of lake size, biodiversity and disturbance

Journal of Freshwater Ecology ◽

10.1080/02705060.2015.1030787 ◽

2015 ◽

Vol 30 (4) ◽

pp. 557-568 ◽

Cited By ~ 2

Author(s):

Thomas A. Clement ◽

Brent A. Murry ◽

Donald G. Uzarski

Keyword(s):

Fish Community ◽

Size Structure ◽

Small Lakes ◽

Community Size ◽

Lake Size

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Modelling recovery of Celtic Sea demersal fish community size-structure

Fisheries Research ◽

10.1016/j.fishres.2012.12.010 ◽

2013 ◽

Vol 140 ◽

pp. 91-95 ◽

Cited By ~ 13

Author(s):

Samuel Shephard ◽

Tak Fung ◽

Axel G. Rossberg ◽

Keith D. Farnsworth ◽

David G. Reid ◽

...

Keyword(s):

Fish Community ◽

Size Structure ◽

Demersal Fish ◽

Community Size ◽

Celtic Sea

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Fishing degrades size structure of coral reef fish communities

10.7287/peerj.preprints.2118 ◽

2016 ◽

Author(s):

James PW Robinson ◽

Ivor D Williams ◽

Andrew M Edwards ◽

Jana McPherson ◽

Lauren Yeager ◽

...

Keyword(s):

Coral Reef ◽

Reef Fish ◽

Fish Community ◽

Size Structure ◽

Fish Communities ◽

Fish Biomass ◽

Community Size ◽

Size Spectra ◽

Coral Reef Ecosystems ◽

Total Fish

Fishing pressure on coral reef ecosystems has been frequently linked to reductions of large fishes and reef fish biomass. Associated impacts on overall community structure are, however, less clear. In size-structured aquatic ecosystems, fishing impacts are commonly quantified using size spectra, which describe the distribution of individual body sizes within a community. We examined the size spectra of coral reef fish communities at 38 US-affiliated Pacific islands, spanning from near pristine to highly human populated. Reef fish community size spectra slopes ‘steepened’ steadily with increasing human population and proximity to market due to a reduction in the relative biomass of large fishes and an increase in the dominance of small fishes. In contrast, total fish community biomass was substantially lower on inhabited islands than uninhabited ones, regardless of human population density. Comparing the relationship between size spectra and reef fish biomass, we found that on populated islands size spectra steepened linearly with declining biomass, whereas on uninhabited islands size spectra and biomass were unrelated. Size spectra slopes also were steeper in regions of low sea surface temperature but were insensitive to variation in other environmental and geomorphic covariates. In contrast, reef fish biomass was highly sensitive to biophysical conditions, being influenced by oceanic productivity, sea surface temperature, island type, and habitat complexity. Our results suggest that community size structure is more robust than total fish biomass to increasing human presence and that size spectra are reliable indicators of exploitation impacts across regions of different fish community compositions, environmental drivers, and fisheries types. Size-based approaches that link directly to functional properties of fish communities, and are relatively insensitive to abiotic variation across biogeographic regions, offer great potential for developing our understanding of fishing impacts in coral reef ecosystems.

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Fishing degrades size structure of coral reef fish communities

10.7287/peerj.preprints.2118v1 ◽

2016 ◽

Author(s):

James PW Robinson ◽

Ivor D Williams ◽

Andrew M Edwards ◽

Jana McPherson ◽

Lauren Yeager ◽

...

Keyword(s):

Coral Reef ◽

Reef Fish ◽

Fish Community ◽

Size Structure ◽

Fish Communities ◽

Fish Biomass ◽

Community Size ◽

Size Spectra ◽

Coral Reef Ecosystems ◽

Total Fish

Fishing pressure on coral reef ecosystems has been frequently linked to reductions of large fishes and reef fish biomass. Associated impacts on overall community structure are, however, less clear. In size-structured aquatic ecosystems, fishing impacts are commonly quantified using size spectra, which describe the distribution of individual body sizes within a community. We examined the size spectra of coral reef fish communities at 38 US-affiliated Pacific islands, spanning from near pristine to highly human populated. Reef fish community size spectra slopes ‘steepened’ steadily with increasing human population and proximity to market due to a reduction in the relative biomass of large fishes and an increase in the dominance of small fishes. In contrast, total fish community biomass was substantially lower on inhabited islands than uninhabited ones, regardless of human population density. Comparing the relationship between size spectra and reef fish biomass, we found that on populated islands size spectra steepened linearly with declining biomass, whereas on uninhabited islands size spectra and biomass were unrelated. Size spectra slopes also were steeper in regions of low sea surface temperature but were insensitive to variation in other environmental and geomorphic covariates. In contrast, reef fish biomass was highly sensitive to biophysical conditions, being influenced by oceanic productivity, sea surface temperature, island type, and habitat complexity. Our results suggest that community size structure is more robust than total fish biomass to increasing human presence and that size spectra are reliable indicators of exploitation impacts across regions of different fish community compositions, environmental drivers, and fisheries types. Size-based approaches that link directly to functional properties of fish communities, and are relatively insensitive to abiotic variation across biogeographic regions, offer great potential for developing our understanding of fishing impacts in coral reef ecosystems.

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Fishing and environment drive spatial heterogeneity in Celtic Sea fish community size structure

ICES Journal of Marine Science ◽

10.1093/icesjms/fsr137 ◽

2011 ◽

Vol 68 (10) ◽

pp. 2106-2113 ◽

Cited By ~ 11

Author(s):

Samuel Shephard ◽

Hans D. Gerritsen ◽

Michel J. Kaiser ◽

Holly S. Truszkowska ◽

David G. Reid

Keyword(s):

Spatial Heterogeneity ◽

Fish Community ◽

Size Structure ◽

Fishing Effort ◽

Trawl Survey ◽

Weak Effect ◽

Community Size ◽

Negative Effect ◽

Celtic Sea ◽

Sea Fish

Abstract Shephard, S., Gerritsen, H. D., Kaiser, M. J., Truszkowska, H. S., and Reid, D. G. 2011. Fishing and environment drive spatial heterogeneity in Celtic Sea fish community size structure. – ICES Journal of Marine Science, 68: 2106–2113. The Large Fish Indicator (LFI) is a univariate size-based indicator of fish community state that has been selected to support the OSPAR fish community Ecological Quality Objective (EcoQO). To operate this EcoQO, a survey-based LFI for each OSPAR region needs to be developed. However, fish communities in these regions are spatially heterogeneous, and there is evidence of within-region spatial variation in the LFI that could confound an overall indicator series. For Celtic Sea trawl-survey sites, spline correlograms indicate positive spatial autocorrelation at a similar range (∼40 km) for the LFI and for fishing effort (h year−1) from vessel monitoring systems. Statistical models reveal a strong negative effect on annual LFI by site of fishing effort within a radius of 40 km. There was a weak effect of fishing within 20 km and no effect at 10 km. LFI also varied significantly with substratum and with local fish community composition identified by a resemblance matrix derived from the survey data. Finally, there was a weak effect of survey year on LFI. Spatial stratification of LFI calculations may be necessary when developing size-based indicators for OSPAR or Marine Strategy Framework Directive regions.

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