The European Water Framework Directive will have instituted the concept of Ecological Quality Status (EQS) as a way to assess the biological quality of water masses. The EQS will be based mainly upon ...the composition of the different biological compartments in the ecosystem specially the benthos as compared to certain reference sites. Such management tools are already well established for freshwater (i.e. biotic indices), but not for coastal and estuarine (i.e. transitional) waters. In the framework of the Seine-Aval programme a workshop on benthic indicators was organized at Wimereux (France) in June 2005. The aim of this workshop and this paper is (1) to present the experiences of the Seine Aval researchers, and the French scientific approaches to benthic indicators, with those international experiences and approaches that have been published or are under development; and (2) to examine the existing benthic tools and their possible use in the characterization of the state of estuarine ecosystems. The debate during the workshop and the numerous recently published on the WFD are discussed in term of the implementation of the WFD in transitional water bodies using benthic indicators and indices. Some proposals for the future underline the needs to re-examine and adapt the different index thresholds, to take into account physical disturbances, to inventory the existing conditions vs reference conditions and to be as pragmatic as possible in using the WFD in transitional waters.
•This paper reviews the use of benthic indices based on the P/A ratio.•BOPA/BO2A indices are used in 23 countries.•BOPA/BO2A indices are used to detect a large variety of human pressures.•Comparisons ...with other benthic indices are biased due to unsatisfied application.
Benthic indices based on the Polychaetes/Amphipods (P/A) ratio have been proposed to assess the environmental quality status of ecosystems in estuarine and coastal waters. Although the methods used to calculate these indices (essentially BOPA and BO2A) have been revised over the past two decades, the underlying approach corresponds to the contrasted responses of two benthic invertebrate groups to pollution, with polychaetes as tolerant/opportunistic species and amphipods as sensitive taxa. The Polychaetes/Amphipods ratio has been tested for monitoring major changes in benthic communities in response to a wide variety of different human pressures in estuarine and coastal environments (oil spills, urban sewage outfalls, enrichment in organic matter, etc.) and is used in 23 countries mainly in Europe, but also in Africa, Asia, Oceania and South America. This paper reviews the use of the P/A ratio (79 documents) in relation to a large panel of human activities, in transitional (estuaries and lagoons) and coastal waters. In some studies, BOPA and BO2A indices based on P/A ratios were selected in certain regions of Spain and Gibraltar to assess the quality of water bodies according to the Water Framework Directive. Moreover, most of these studies do not meet the necessary conditions for application of the indices. As a result, comparisons between P/A ratios and other benthic indices are inappropriate when assessing ecological quality status, which therefore reinforces the need to apply P/A ratios with precaution.
An updated checklist for 2022 of amphipods from the English Channel (La Manche) is given for eight geographical zones. This revision brings the inventory of 1999 up to date with recent data from the ...Normano-Breton Gulf and other studies focused on non-indigenous fauna, as well as recent data from benthic and suprabenthic studies, mainly in the eastern part of the English Channel (EC). The total number of species in the entire EC is 269. The number of species is much higher in the western basin (WEC) than it is in the eastern basin (EEC) or in the central part of the EC. The amphipod species listed here are distributed between the eight zones as follows: French WEC: 201 species; English WEC: 194; Normano-Breton Gulf: 224; Bay of Seine: 172; Wight: 97; French EEC: 149; English EEC: 64; and Central EC: 61. Of these species, 180 are present in both basins of the EC, while 78 are present only in the western basin and 11 are present only in the eastern basin. The low number of amphipods (<100) recorded in three of the eight zones is probably due to the lack of observations in these parts of the EC. Among the 269 amphipod species recorded with confidence in the EC, 24 are new to the EC since 1999, 12 are non-indigenous species, and 44 are observed only in one of the eight zones, mainly in the three zones of the western basin of the EC.
With about 8000 marine benthic species, the amphipod crustaceans form one of the richest animal groups of the worldwide Ocean. They have colonized a wide range of soft- and hard-bottom natural and ...artificial habitats extending from the intertidal to hadal zones. Moreover, they show a broad size spectrum, with numerous giant species exceeding 20 cm in length and some species smaller than 2 mm. When biofouling artificial hard surfaces, some tube-building species can form very dense populations comprising up to 100,000 individuals per square meter. Amphipods are important prey for fish and mammals. Along with cephalopod juveniles, they are also included in the trophic diet of shorebirds that consume amphipods mostly during the low tide on tidal flats. They display diel migration, which reinforces the predation by demersal fish in the suprabenthic zone just above the sea bed, as well as by pelagic fish in the water column. Despite their importance in terms of biodiversity and trophic transfer, no general overview is available on the role of benthic amphipods in marine ecosystem food webs. Various methods, including laboratory and field experiments, as well as the analysis of stomach contents and DNA extraction, have been used to identify the prey/predator trophic links. Based on an extensive literature review, this study discusses the role of marine benthic amphipods as potential food for higher trophic levels in natural and artificial hard-bottom communities created via the construction of offshore wind farms.
•BACI approach apply before Offshore Wind Farm (OWF) construction.•Dieppe Le Tréport OWF site includes three different sedimentary habitats.•Annelids were the most abundant group in the three ...habitats followed by Arthropods and Molluscs.•Biomasses are among the highest recorded, reflecting the area importance o as a biomass hotspot in the English Channel.
Offshore Wind Farms (OWFs) in the English Channel and along the coast of Normandy (France) will be installed on coarse sediments, which cover about 80% of the seabed of the English Channel. A BACI (Before After Control Impact) approach has been recommended by the French State for each of these OWFs. This provides the opportunity to acquire macrofauna data and assess the Ecological Quality Status in areas that are poorly sampled. In the case of the Dieppe-Le Tréport (DLT) OWF, for that, a sampling strategy was developed in 2014–2016 to establish a ‘Before’ state for the sediment and macrofauna. Results highlight that the DLT OWF project site includes three different sediment type: sandy Gravel (sG), gravelly Sand (gS) and medium Sand (mS). Taxonomic Richness and abundances are dominated by Annelids in all three habitats, followed by Arthropods and Molluscs. In terms of biomass, Molluscs (bivalves) are predominant in sG and gS, while Echinoderms and Polychaetes along with bivalves represent a high fraction of the biomass in mS. Surface Deposit Feeders are the most important group in terms of abundance, while Filter feeders largely dominate the biomass. The benthic indices based on abundances reveal a high Ecological Quality Status for the three sediment types. However, due to the predominant contribution of the bivalve Glycymeris glycymeris to the biomass, the habitat quality appears to vary from moderate to bad. In comparison with other similar habitats, the Taxonomic Richness and Abundances of coarse sediments and medium sand are in the same order of magnitude as other sites. However, the biomasses are among the highest so far recorded, reflecting the importance of this area as a hotspot of biomass in the English Channel.
•Dispersal of amphipod Ampelisca during their diel migration in the water column is simulated.•ICHTHYOP larval dispersal model is coupled with the hydrodynamic model CROCO.•Tidal currents and winds ...serve to Ampelisca dispersal considered as passive particles.•The dispersion concerns the fine sand community (6 km²) population of the Bay of Morlaix.•Pelagic presence of Ampelisca along the night appear to be excessively dispersive.
The aim of this study is to analyse and model the dispersal of Ampelisca, a benthic genus of amphipod crustaceans, in the fine sand community of the Bay of Morlaix (western English Channel), during their nocturnal migration in the water column. Based on sampling of the suprabenthos (in the water column adjacent to the bottom) and surface plankton on 17 June 1994, Dauvin and Zouhiri (1996) studied the vertical distribution of Ampelisca during a spring swarming reproductive period. Statistical modelling techniques and specific numerical models were combined to simulate the effects of tidal currents, wind direction and speed on Ampelisca dispersal. As an illustration to constant pluriannual seasonal pattern, the dispersion of Ampelisca individuals considered as passive particles was studied at two reproductive periods, on a short night (17th-18th June 1994) during a neap tide, and on long night (7th-8th September 1994) during a spring tide. These models are used to investigate whether Ampelisca can be dispersed beyond the fine sand community in the immediate area of their small-scale benthic habitat (only 6 km²) during their diel vertical migration. According to the results, the speed and direction of currents will determine the trajectory of Ampelisca and the degree of dispersal outside their benthic habitat during a nighttime pelagic sortie. These simulations, particularly during spring tides, are incompatible with population stability, as they appear to be excessively dispersive. Short-term dispersal simulations for twenty minutes in the plankton allow the optimal return of individuals to the fine sand benthic habitats. We hypothesize there is an adaptative advantage for Ampelisca over time to short diel migrations. However, we currently do not know whether each individual makes a single migration, or several migrations in the water column during a night.
Anthropogenic activities including coastal industries, urbanization, extensive agriculture and aquaculture as well as their cumulative impacts represent major sources of perturbation of marine ...coastal systems. Macrobenthic communities are useful ecological indicators for monitoring the health status of marine environments (or polluted environments). The present study reports, for the first time, the response of benthic macrofauna sampled during two years survey (2015–2016) to multiple anthropogenic pressures on the coastal zone south of Sfax (Tunisia). A total of 12 stations were monitored seasonally at locations downstream from the main potential sources of disturbance. 106 macrobenthos taxa, belonging to six animal phyla and 70 families, were identified with a dominance of polychaetes (42%), crustaceans (35%) and molluscs (18%). We used an ANOVA test and cluster analysis to identify spatial gradient linked to environmental and anthropogenic factors, including depth, sedimentary texture and anthropogenic activities (i.e. phosphogypsum discharges).The macrofauna present lowest species number and abundance on stations undergoing anthropogenic inputs, which are extremely polluted by heavy metals (Cd, Cu, F and N) and excess of organic matter. Univariate parameters reveal a general trend of increasing species diversity with increasing distance from the pollution source. The polluted stations are strongly dominated by carnivores, and selective deposit feeders, and more closely linked to the availability of trophic resources than to anthropogenic constraints. The seasonal changes in macrobenthic abundance, diversity indices and community structure are mainly linked to the biological cycle (e.g. recruitment events) of the dominant species. Biotic indices (AMBI and BO2A) classified the coastal zone south of Sfax as moderate and good ecological status. This study suggests that initiating a long-term monitoring programme would improve our understanding of the temporal changes of macrobenthic communities of this ecosystem, contributing to the assessment of effective management and conservation measures in this disturbed area.
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•Coastal zone south of Sfax (Tunisia) is subject to intensive anthropogenic pressures.•Macrofauna community is poorly diversified at shallowest stations undergoing to anthropogenic pressures.•Three macrobenthic assemblages are identified in the coastal zone linked to environmental and anthropogenic factors.•Using the biotic indices, the coastal zone of Sfax can be classified as moderate to good ecological status.
The structure, diversity, spatial and seasonal distributions of amphipod assemblages associated with intertidal Zostera (Zosterella) noltei meadows were studied around the Kneiss Islands (central ...Mediterranean Sea). This site represents a site of international interest in terms of its ornithological diversity (Important Bird Area, Ramsar Site and SPAMI). The amphipod fauna was sampled at 32 stations in spring 2014. A total of 6,482 individuals belonging to 78 species and 22 families were identified; among these taxa, Lysianassa ceratina is new for the Tunisian amphipod inventory, whereas 25 species are identified for the first time in the Gulf of Gabès. The dominant species are Cymadusa filosa, Microdeutopus gryllotalpa, Gammarus insensibilis, Dexamine spiniventris, Monocorophium insidiosum, Elasmopus rapax, Melita palmata and Leucothoe incisa. Four amphipod assemblages are identified using MDS analysis. The distribution of amphipod assemblages is linked to several environmental factors, such as sediment type, organic matter content and distance from the shore, which is itself associated with a clear inshore–offshore gradient. Seasonal variations of the amphipod assemblage patterns at eight stations, sampled between April 2014 and January 2015, show a maximum abundance and diversity during summer and autumn, with a minimum in winter. These seasonal fluctuations may be related to many factors such as variations of climatic factors (e.g. temperature, salinity), the growth and production rates of Zostera noltei meadows and seasonal patterns in the life cycle of dominant species.
Marine renewable energy developments (MREDs) are rapidly expanding in size and number as society strives to maintain electricity generation whilst simultaneously reducing climate-change linked CO2 ...emissions. MREDs are part of an ongoing large-scale modification of coastal waters that also includes activities such as commercial fishing, shipping, aggregate extraction, aquaculture, dredging, spoil-dumping and oil and gas exploitation. It is increasingly accepted that developments, of any kind, should only proceed if they are ecologically sustainable and will not reduce current or future delivery of ecosystem services. The benthos underpins crucial marine ecosystem services yet, in relation to MREDs, is currently poorly monitored: current monitoring programmes are extensive and costly yet provide little useful data in relation to ecosystem-scale-related changes, a situation called ‘data-rich, information-poor’ (DRIP). MRED –benthic interactions may cause changes that are of a sufficient scale to change ecosystem services provision, particularly in terms of fisheries and biodiversity and, via trophic linkages, change the distribution of fish, birds and mammals. The production of DRIPy data should be eliminated and the resources used instead to address relevant questions that are logically bounded in time and space. Efforts should target identifying metrics of change that can be linked to ecosystem function or service provision, particularly where those metrics show strongly non-linear effects in relation to the stressor. Future monitoring should also be designed to contribute towards predictive ecosystem models and be sufficiently robust and understandable to facilitate transparent, auditable and timely decision-making.
•Ecopath models before/after an offshore wind farm were built.•Possible reef effect would increase total system biomass by 55%.•Bivalves build-up would lead to a food web dominated by ...detritivory.•Benthos and keystone fish biomass increases attracted apex predators.
As part of the energy transition, the French government is planning the construction of three offshore wind farms in Normandy (Bay of Seine and eastern part of the English Channel, north-western France) in the next years. These offshore wind farms will be integrated into an ecosystem already facing multiple anthropogenic disturbances such as maritime transport, fisheries, oyster and mussel farming, and sediment dredging. Currently no integrated, ecosystem-based study on the effects of the construction and exploitation of offshore wind farms exists, where biological approaches generally focused on the conservation of some valuable species or groups of species. Complementary trophic web modelling tools were applied to the Bay of Seine ecosystem (to the 50km2 area covered by the wind farm) to analyse the potential impacts of benthos and fish aggregation caused by the introduction of additional hard substrates from the piles and the turbine scour protections. An Ecopath ecosystem model composed of 37 compartments, from phytoplankton to seabirds, was built to describe the situation “before” the construction of the wind farm. Then, an Ecosim projection over 30 years was performed after increasing the biomass of targeted benthic and fish compartments. Ecological Network Analysis (ENA) indices were calculated for the two periods, “before” and “after”, to compare network functioning and the overall structural properties of the food web. Our main results showed (1) that the total ecosystem activity, the overall system omnivory (proportion of generalist feeders), and the recycling increased after the construction of the wind farm; (2) that higher trophic levels such as piscivorous fish species, marine mammals, and seabirds responded positively to the aggregation of biomass on piles and turbine scour protections; and (3) a change in keystone groups after the construction towards more structuring and dominant compartments. Nonetheless, these changes could be considered as limited impacts of the wind farm installation on this coastal trophic web structure and functioning.
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