Diversity and community structure of epibenthic invertebrates and fish in the North Sea

Abstract

The structure of North Sea benthic invertebrate and fish communities is an important indicator of anthropogenic and environmental impacts. Although North Sea fish stocks are monitored regularly, benthic fauna are not. Here, we report the results of a survey carried out in 2000, in which five nations sampled the epibenthic and fish fauna at 270 stations throughout the North Sea. The aim of the survey was to investigate the diversity and community structure of epibenthic and fish communities and to identify relationships with environmental factors, including the frequency of commercial otter and beam trawling disturbance. Epibenthic species diversity was lower in the southern North Sea than in central and northern areas. Fish, conversely, were more diverse in the south. The 50 m, 100 m and 200 m depth contours broadly defined the boundaries of benthic and fish communities. The abundance of epibenthos of the southern North Sea was dominated by free-living species, whilst north of the 50 m contour sessile species prevailed. A hybrid area, with sessile species typical of the north and free-living species characteristic of the south, was found off the Norfolk and Flamborough coast stretching towards the Dogger Bank. Large-scale hydrodynamic phenomena were most likely to be responsible for the main divisions between communities, especially the boundary between mixed and stratified water masses. However, bottom temperature, sediment parameters and beam trawling were closely correlated with species richness and diversity, as well as community patterns, and may modify regional species composition. Our study shows that effective large-scale sampling of benthic communities can be conducted during existing fisheries surveys. Since annual fisheries surveys are conducted throughout the northeast Atlantic shelf seas, concurrent benthic surveys would allow benthic sampling on unprecedented spatial and temporal scales. The samples would help to monitor the environmental impacts of trawling disturbance, climate change, pollution and other natural and anthropogenic factors

Fish Community Structure of Sandha River: A Link Analysis towards Fisheries Management and Conservation

“…In the feedback, three majors groups were formed of which the first group observed as dominating characters where the second group had less dominating behavior and some of them season dependent and third group recognized as mostly season dependent and some of them were alien species. The findings of the present study were more or less similar to other studies [45][46][47][48].…”

Benthos and demersal fish habitats in the German Exclusive Economic Zone (EEZ) of the North Sea

“…This seems to be true also for the German EEZ, because Rachor and Nehmer (2003) found similar patterns to those described by Salzwedel et al (1985) in the 1980s and Hagmeier (1925) in 1920s, indicating that no considerable and permanent changes of infauna community structure occurred over a period of almost 80 years. This might be partly explained by the comparatively stable sediment distribution in the EEZ, which is a more important habitat characteristic for benthic infauna than for other faunal components (Callaway et al 2002;Schratzberger et al 2006). Otherwise, it is reasonable that the general community structure of fish, epifauna and infauna characterizing the habitats coast, Oysterground and Ducks Bill remained rather stable over time since abiotic habitat characteristics such as different strength in seasonality of, for example, temperature have a larger influence on the general community structure than, for example, gradual warming of the water column due to climate change.…”

“…Most of these studies have identified the 50-m depth contour in the North Sea as a conspicuous boundary separating fish, epifauna and infauna communities since it closely matches the boundary between mixed and stratified waters and is, thus, related to abrupt changes in the abiotic environment. Additionally, epifauna and infauna diversity was found to be lower in the southern North Sea than in central and northern parts, while conversely fish diversity was highest near the major inflows of Atlantic water masses in the North Sea (Fair Isle, East Shetland and English Channel) (Callaway et al 2002;Reiss et al 2010).…”

“…Since the beginning of such investigations, effort increased to analyse spatial community structure of fish (Greenstreet and Hall 1996;Ehrich et al 2009), benthic infauna (Duineveld et al 1991;Heip et al 1992;Künitzer et al 1992;Kröncke et al 2011) and benthic epifauna (Frauenheim et al 1989;Jennings et al 1999;Zühlke et al 2001) on a North Sea wide scale. However, similarities and the interrelationships in community structure between these faunal components were only recently studied, for example by Callaway et al (2002) and Reiss et al (2010). Most of these studies have identified the 50-m depth contour in the North Sea as a conspicuous boundary separating fish, epifauna and infauna communities since it closely matches the boundary between mixed and stratified waters and is, thus, related to abrupt changes in the abiotic environment.…”

“…Additionally, the spatial resolution of large-scale studies was often not sufficient to meet national management requirements. Callaway et al (2002), for instance, only defined two epifauna communities and one fish community by analysing approximately 10 stations in the area of the German EEZ. Reiss et al (2010) found three epifauna and two fish communities based on 25 stations.…”