Using large benthic macrofauna to refine and improve ecological indicators of bottom trawling disturbance

McLaverty, Ciarán; Eigaard, Ole Ritzau; Gislason, Henrik; Bastardie, François; Brooks, Mollie Elizabeth; Jönsson, Patrik; Lehmann, Andreas; Dinesen, Grete E.

doi:10.1016/j.ecolind.2019.105811

Cited by 29 publications

(21 citation statements)

References 72 publications

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“…Generalised linear mixed models (GLMMs) were used to model 3 community indicators: density, biomass, and functional richness, chosen based on their sensitivity to trawling disturbance in Danish waters (McLaverty et al 2020). Density and biomass were calculated as the total number and biomass of individuals in a sample, respectively.…”

Section: Univariate Analysis: Community Indicatorsmentioning

confidence: 99%

High-resolution fisheries data reveal effects of bivalve dredging on benthic communities in stressed coastal systems

McLaverty

Eigaard

Dinesen

et al. 2020

Mar. Ecol. Prog. Ser.

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Commercial dredging for blue mussels (Mytilus edulis) and oysters (Ostrea edulis, Crassostrea gigas) constitute the main bivalve fisheries in Denmark. These activities predominantly take place in Limfjorden, a large microtidal sound, and in the Inner Danish waters. Both areas are shallow, estuarine, receive high nutrient inputs from agriculture, and are of nature conservation interest (Natura 2000 sites), thus presenting challenges for an ecosystem approach to fisheries management. Using high-resolution fisheries data (~10 m), we investigated the effects of bivalve dredging on benthic communities at both local (Natura 2000 site) and regional (fishery-wide) scales. Regionally, our results showed that dredging intensity correlated with shifts in species composition and reduced community biomass. We were, however, unable to detect an effect of dredging on community density, trait richness, and trait composition. These metrics were significantly related to other environmental drivers, such as sediment organic content (negative) and mussel bed biomass (positive). At the local scale, the observed relationships between dredging, biomass, and species composition varied significantly. This occurred as dredging impacts were greater in areas that contained suitable reference conditions and experienced relatively low levels of disturbance. By contrast, communities which experienced high nutrient loading, regular anoxic events, and high natural variability were relatively unaffected by dredging. Our results therefore highlight the importance of spatial scales in fishing impact estimations. Furthermore, we demonstrate how targeted sampling, high-resolution fisheries data, and suitable reference areas can be used to detect fishery effects in coastal areas that are highly stressed by eutrophication.

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Section: Univariate Analysis: Community Indicatorsmentioning

confidence: 99%

High-resolution fisheries data reveal effects of bivalve dredging on benthic communities in stressed coastal systems

McLaverty

Eigaard

Dinesen

et al. 2020

Mar. Ecol. Prog. Ser.

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“…McLaverty et al [55] drew attention to the interest of using large (>4 mm) instead of small (1-4 mm) macrofauna to detect bottom trawling. Indeed, they found that stronger relationships exist between trawling intensity and large rather than small macrofauna response, and they argued that small macrofauna are typically characterized by high density, diversity, and population growth rates, and their relative resilience to trawling may mask the response of the more sensitive macrofauna [55]. This is probably also the case in the work of Dannheim [31], who failed to highlight the consequences of trawling on infauna communities.…”

Section: Performance Of the Indices And Ecological Considerationmentioning

confidence: 99%

“…TDI did not perform well, but only a few observations could be taken into account as a consequence of the poor match between the dataset and the functional trait table [16]. Further, this can also be related to the masking effect of resilient and high-density species ( [55] see below). Here, the decrease in species richness is so important [35] that all indices that take it or the loss of species into account (GPBI, M-AMBI) can detect the hypoxia events compared to those that do not (TDI).…”

Section: Performance Of the Indices And Ecological Considerationmentioning

confidence: 99%

A General-Purpose Biotic Index to Measure Changes in Benthic Habitat Quality across Several Pressure Gradients

Labrune

Gauthier

Conde

et al. 2021

JMSE

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Realistic assessments of the ecological status of benthic habitats, as requested by European directives such as the Water Framework Directive and the European Marine Strategy Framework Directive, require biotic indices capable of detecting anthropogenic impact without having preliminary knowledge of the occurring pressures. In this context, a new general-purpose biotic index (GPBI) based on the deviation of benthic macrofauna community composition and structure from a valid reference (i.e., good ecological status) is proposed. GPBI is based on the assumption that as a site becomes impacted by a pressure, the most sensitive species are the first to disappear, and that stronger impacts lead to more important losses. Thus, it explicitly uses the within-species loss of individuals in the tested station in comparison to one or several reference stations as the basis of ecological status assessment. In this study, GPBI is successfully used in four case studies considering the impact of diversified pressures on benthic fauna: (1) maerl extraction in the northern Bay of Biscay, (2–3) dredging and trawling in the North Sea, and (4) hypoxic events at the seafloor in the Gullmarfjord. Our results show that GPBI was able to efficiently detect the impact of the different physical disturbances as well as that of hypoxia and that it performs better than commonly used pressure-specific indices (M-AMBI and TDI). Signal detection theory was used to propose a sound good/moderate ecological quality status boundary, and recommendations for future monitoring are also provided based on the reported performance of GPBI.

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“…The sampling efficiency differs when catching various components of the communities, including for the catching of animals from different size groups. (McLaverty et al 2020) and gears that sample bigger animals will catch a more significant fraction of long-lived fauna. The integration of other sampling gears will capture other components of the benthic community and likely strengthen the overall assessment.…”

Section: Management Scenarios and Seafloor Statusmentioning

confidence: 99%

Reducing fisheries impacts on the seafloor: A bio-economic evaluation of policy strategies for improving sustainability in the Baltic Sea

et al. 2020

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Using large benthic macrofauna to refine and improve ecological indicators of bottom trawling disturbance

Cited by 29 publications

References 72 publications

High-resolution fisheries data reveal effects of bivalve dredging on benthic communities in stressed coastal systems

High-resolution fisheries data reveal effects of bivalve dredging on benthic communities in stressed coastal systems

A General-Purpose Biotic Index to Measure Changes in Benthic Habitat Quality across Several Pressure Gradients

Reducing fisheries impacts on the seafloor: A bio-economic evaluation of policy strategies for improving sustainability in the Baltic Sea

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