The effects of trawling and primary production on size-structured food webs in seabed ecosystems

Understanding how different drivers shape relationships between abundance and body mass (size spectra) is important for understanding trophic and competitive interactions in food webs and for predicting the effects of human pressures. Here, we sample seabed communities from small polychaetes (<0.001 g) to large fish (>1 kg) in the Celtic Sea and the western English Channel to examine how bottom trawling and primary production affect their size spectra and to compare these with predictions from a model that couples predator and detritivore communities. Size spectra were not well approximated by linear fits because of truncation of the size spectra of detritivores. Low primary production resulted in lower abundance of benthic fauna. Bottom trawling reduced the abundance of predators and large detritivores but allowed small detritivores to increase in abundance. These empirical size spectra were partly consistent with predictions from the size spectra model, showing that understanding the structuring of benthic communities requires a consideration of both size and functional group. The findings highlight the need for an ecosystem approach to understanding the effects of exploitation and climate change on marine ecosystems.

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The Southern Ocean benthic fauna and climate change: a historical perspective

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.1992.0150 ◽

1992 ◽

Vol 338 (1285) ◽

pp. 299-309 ◽

Cited By ~ 143

Keyword(s):

Global Warming ◽

Southern Ocean ◽

Environmental Change ◽

Benthic Communities ◽

Benthic Fauna ◽

Marine Fauna ◽

Short Term Change ◽

Term Change ◽

Continental Ice Sheets

Environmental change is the norm and it is likely that, particularly on the geological timescale, the temperature regime experienced by marine organisms has never been stable. These temperature changes vary in timescale from daily, through seasonal variations, to long-term environmental change over tens of millions of years. Whereas physiological work can give information on how individual organisms may react phenotypically to short-term change, the way benthic communities react to long-term change can only be studied from the fossil record. The present benthic marine fauna of the Southern Ocean is rich and diverse, consisting of a mixture of taxa with differing evolutionary histories and biogeographical affinities, suggesting that at no time in the Cenozoic did continental ice sheets extend sufficiently to eradicate all shallow-water faunas around Antarctica at the same time. Nevertheless, certain features do suggest the operation of vicariant processes, and climatic cycles affecting distributional ranges and ice-sheet extension may both have enhanced speciation processes. The overall cooling of southern high-latitude seas since the mid-Eocene has been neither smooth nor steady. Intermittent periods of global warming and the influence of Milankovitch cyclicity is likely to have led to regular pulses of migration in and out of Antarctica. The resultant diversity pump may explain in part the high species richness of some marine taxa in the Southern Ocean. It is difficult to suggest how the existing fauna will react to present global warming. Although it is certain the fauna will change, as all faunas have done throughout evolutionary time, we cannot predict with confidence how it will do so.

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A stochastic, Lagrangian model of sinking biogenic aggregates in the ocean (SLAMS 1.0): model formulation, validation and sensitivity

Geoscientific Model Development ◽

10.5194/gmd-9-1455-2016 ◽

2016 ◽

Vol 9 (4) ◽

pp. 1455-1476 ◽

Cited By ~ 18

Author(s):

Tinna Jokulsdottir ◽

David Archer

Keyword(s):

Primary Production ◽

Degradation Kinetics ◽

Mechanistic Model ◽

Euphotic Zone ◽

Lagrangian Model ◽

Zooplankton Grazing ◽

Aggregate Model ◽

Size Spectra ◽

Sea Floor ◽

Individual Particles

Abstract. We present a new mechanistic model, stochastic, Lagrangian aggregate model of sinking particles (SLAMS) for the biological pump in the ocean, which tracks the evolution of individual particles as they aggregate, disaggregate, sink, and are altered by chemical and biological processes. SLAMS considers the impacts of ballasting by mineral phases, binding of aggregates by transparent exopolymer particles (TEP), zooplankton grazing and the fractal geometry (porosity) of the aggregates. Parameterizations for age-dependent organic carbon (orgC) degradation kinetics, and disaggregation driven by zooplankton grazing and TEP degradation, are motivated by observed particle fluxes and size spectra throughout the water column. The model is able to explain observed variations in orgC export efficiency and rain ratio from the euphotic zone and to the sea floor as driven by sea surface temperature and the primary production rate and seasonality of primary production. The model provides a new mechanistic framework with which to predict future changes on the flux attenuation of orgC in response to climate change forcing.

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Role of microhabitats in food webs of benthic communities in a mangrove forest

Marine Ecology Progress Series ◽

10.3354/meps340055 ◽

2007 ◽

Vol 340 ◽

pp. 55-62 ◽

Cited By ~ 35

Author(s):

K Kon ◽

H Kurokura ◽

K Hayashizaki

Keyword(s):

Food Webs ◽

Mangrove Forest ◽

Benthic Communities

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Light availability in the coastal ocean: impact on the distribution of benthic photosynthetic organisms and contribution to primary production

Biogeosciences Discussions ◽

10.5194/bgd-3-895-2006 ◽

2006 ◽

Vol 3 (4) ◽

pp. 895-959 ◽

Cited By ~ 32

Author(s):

J.-P. Gattuso ◽

B. Gentili ◽

C. M. Duarte ◽

J. A. Kleypas ◽

J. J. Middelburg ◽

...

Keyword(s):

Primary Production ◽

Surface Area ◽

Coastal Zone ◽

Benthic Communities ◽

Light Availability ◽

Coastal Ocean ◽

Shelf Area ◽

Primary Producers ◽

Benthic Primary Production ◽

Photosynthetic Organisms

Abstract. One of the major features of the coastal zone is that part of its sea floor receives a significant amount of sunlight and can therefore sustain benthic primary production by seagrasses, macroalgae, microphytobenthos and corals. However, the contribution of benthic communities to the primary production of the global coastal ocean is not known, partly because the surface area where benthic primary production can proceed is poorly quantified. Here, we use a new analysis of satellite (SeaWiFS) data collected between 1998 and 2003 to estimate, for the first time at a nearly global scale, the irradiance reaching the bottom of the coastal ocean. The following cumulative functions provide the percentage of the surface of the coastal zone receiving an irradiance greater than Ez: PaNon-polar=28.80−16.69 log10(Ez)+0.84 log102(Ez)+0.83 log103(Ez) PaArctic=16.01−15.67 log10(Ez)+2.03 log102(Ez)+1.00 log103(Ez) Data on the constraint of light availability on the major benthic primary producers and net primary production are reviewed. Some photosynthetic organisms can grow deeper than the nominal bottom limit of the coastal ocean (200 m). The minimum irradiance required varies from 0.4 to 5.1 mol photons m−2 d−1 depending on the group considered. The daily compensation irradiance of benthic communities ranges from 0.24 to 4.4 mol photons m−2 d−1. Data on benthic irradiance and light requirements are combined to estimate the surface area of the coastal ocean where (1) light does not limit the distribution of primary producers and (2) net community production (NCP, the balance between gross primary production and respiration) is positive. Positive benthic NCP can occur over 37% of the global shelf area. The limitations of this approach, related to the spatial resolution of the satellite data, the parameterization used to convert reflectance data to irradiance, and the relatively limited biological information available, are discussed.

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Evidence for benthic-pelagic food web coupling and carbon export from California margin bamboo coral archives

Biogeosciences Discussions ◽

10.5194/bgd-11-2595-2014 ◽

2014 ◽

Vol 11 (2) ◽

pp. 2595-2621 ◽

Cited By ~ 1

Author(s):

T. M. Hill ◽

C. R. Myrvold ◽

H. J. Spero ◽

T. P. Guilderson

Keyword(s):

Primary Production ◽

Deep Sea ◽

Benthic Communities ◽

California Current ◽

Strong Relationship ◽

Nitrogen Isotope ◽

Carbon Export ◽

Carbon And Nitrogen ◽

Pelagic Food Webs

Abstract. Deep-sea bamboo corals (order Gorgonacea, family Isididae) are known to record changes in water mass chemistry over decades to centuries. These corals are composed of a two-part skeleton of calcite internodes segmented by gorgonin organic nodes. We examine the spatial variability of bamboo coral organic node 13C/12C and 15N/14N from thirteen bamboo coral specimens sampled along the California margin (37–32° N; 792 to 2136 m depth). Radiocarbon analyses of the organic nodes show the presence of the anthropogenic bomb spike, indicating the corals utilize a surface-derived food source (pre-bomb D14C values of ∼ −100‰, post-bomb values to 82‰). Carbon and nitrogen isotope data from the organic nodes (13C = −15.9‰ to −19.2‰ 15N = 13.8‰ to 19.4‰) suggest selective feeding on surface-derived organic matter or zooplankton. A strong relationship between coral 15N and habitat depth indicate a potential archive of changing carbon export, with decreased 15N values reflecting reduced microbial degradation (increased carbon flux) at shallower depths. Using four multi-centennial length coral records, we interpret long-term 15N stability in the California Current. Organic node 13C values record differences in carbon isotope fractionation dictated by nearshore vs. offshore primary production. These findings imply strong coupling between primary production, pelagic food webs, and deep-sea benthic communities.

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Sensitivity of ecosystem functioning to changes in trophic structure, functional group composition and species diversity in belowground food webs

Ecological Research ◽

10.1046/j.1440-1703.2002.00480.x ◽

2002 ◽

Vol 17 (2) ◽

pp. 207-215 ◽

Cited By ~ 45

Author(s):

Heikki Setälä

Keyword(s):

Species Diversity ◽

Food Webs ◽

Ecosystem Functioning ◽

Trophic Structure ◽

Functional Group ◽

Group Composition

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Evaluating impacts of bottom trawling and hypoxia on benthic communities at the local, habitat, and regional scale using a modelling approach

ICES Journal of Marine Science ◽

10.1093/icesjms/fsz219 ◽

2019 ◽

Vol 77 (1) ◽

pp. 278-289 ◽

Cited By ~ 1

Author(s):

P D van Denderen ◽

S G Bolam ◽

R Friedland ◽

J G Hiddink ◽

K Norén ◽

...

Keyword(s):

Baltic Sea ◽

Spatial Scales ◽

Benthic Communities ◽

Regional Scale ◽

The Baltic Sea ◽

Benthic Habitats ◽

Bottom Trawling ◽

Management Actions ◽

The Baltic ◽

Local Habitat

Abstract Bottom trawling disturbance and hypoxia are affecting marine benthic habitats worldwide. We present an approach to predict their effects on benthic communities, and use the approach to estimate the state, the biomass relative to carrying capacity, of the Baltic Sea at the local, habitat, and regional scale. Responses to both pressures are expected to depend on the longevity of fauna, which is predicted from benthic data from 1558 locations. We find that communities in low-salinity regions mostly consist of short-lived species, which are, in our model, more resilient than those of the saline areas. The model predicts that in 14% of the Baltic Sea region benthic biomass is reduced by at least 50%, whereas an additional 8% of the region has reductions of 10–50%. The effects of hypoxia occur over larger spatial scales and lead to a low state of especially deep habitats. The approach is based on a simple characterization of the benthic community, which comes with high uncertainty, but allows for the identification of benthic habitats that are at greatest risk and prioritization of management actions at the regional scale. This information supports the development of sustainable approaches to manage impact of human activities on benthic ecosystems.

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Benthic communities in an estuary with periodic deoxygenation

Marine and Freshwater Research ◽

10.1071/mf9810227 ◽

1981 ◽

Vol 32 (2) ◽

pp. 227 ◽

Cited By ~ 25

Author(s):

SF Rainer ◽

RC Fitzhardinge

Keyword(s):

New South ◽

Benthic Communities ◽

Benthic Fauna ◽

Common Species ◽

Central Basin ◽

Deep Basin ◽

South Wales ◽

The Relationship ◽

Range Of Values ◽

Zostera Capricorni

The relationship between spatial patterns in the physical environment and patterns in community and trophic structure in the benthic fauna was investigated in an estuary with periodic deoxygenation of the near- bottom water. Six sites were sampled between intertidal mangroves and an 8 m deep basin of Port Hacking, N.S.W. A total of 163 species was collected, ranging from 11 to 94 at each site. Both frequency and biomass were least in the central basin and highest in a bed of the seagrass Zostera capricorni Aschers. The abundances at these sites encompass the range of values previously recorded for estuaries on the east coast of Australia. The dominant species differed from those reported from other New South Wales estuaries, although the same species were usually present. The distribution of common species was limited by fluctuations in dissolved oxygen levels, but not obviously so by sediment differences or short-term fluctuations in water temperature or salinity. Frequency-based diversity and evenness values were similar to those from other estuarine areas. Biomass-based values were lower at most sites than frequency-based values. Patterns of diversity and evenness could not be simply interpreted as indicators of environmental harshness in the community.

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

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f05-261 ◽

2006 ◽

Vol 63 (4) ◽

pp. 810-820 ◽

Cited By ~ 11

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, predatorprey interactions, and biomass standing stock and was later applied to fish communities as lengthfrequency 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.

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