Long-term studies of macrozoobenthos in intertidal and shallow subtidal habitats near the island of Norderney (East Frisian coast, Germany)

Dörjes, Jürgen; Michaelis, H.; Rhode, Birgit

doi:10.1007/978-94-009-4049-9_20

Cited by 22 publications

(32 citation statements)

References 15 publications

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“…But these changes were based mainly on a highly successful recruitment of echinoderms in 1996, which is known to be patchy (Ò lafsson et al 1994;Thie´baut et al 1998), and not by a decrease in abundance or number of species. Highly successful recruitment after cold winters was found for several benthic species (Do¨rjes et al 1986;Beukema et al 2001;Kro¨ncke et al 2001;Strasser et al 2003). However, since most benthic species disperse via pelagic larvae, local recruitment is often decoupled from local reproduction (Bosselmann 1991;Caley et al 1996;Eckert 2003).…”

Section: Community Structurementioning

confidence: 99%

“…In the Dutch Wadden Sea the effect of the cold winter 1978/1979 was more evident in the lower than at the higher tidal flats (Beukema 1990). In the benthic community at Norderney (East Frisian Wadden Sea) the sublitoral was found more affected by the severe winter of 1978/1979 than the littoral (Do¨rjes et al 1986). In the German Bight Schroeder (2003) found that the sublitoral macrofauna was more affected by the cold winter 1995/1996 at an offshore station in the Oyster Ground than at the nearshore stations.…”

Section: Introductionmentioning

confidence: 99%

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Cold winter effects on benthic macrofauna communities in near- and offshore regions of the North Sea

2006

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In order to investigate the effect of severe winters on the long-term variability of benthic macrofauna communities four stations from the inner German Bight towards the Dogger Bank (North Sea) were sampled in March 1990 and from May 1995 to 2002. The stations were chosen to reflect a gradient in the hydrographic regime, temperature and organic matter supply. We initially hypothesized that the effect of severe winters on benthic communities will be more pronounced in the offshore more stable environment than in the nearshore regions. Our results clearly showed the opposite pattern. The benthic communities at the nearshore stations in the German Bight changed dramatically in species abundance and community structure after the severe winter 1995/1996. But the community structure in the German Bight returned to the previous stage within 2 years. In contrast, the offshore stations in the Oyster Ground and at the Dogger Bank remained rather unaffected by the severe winter and changed gradually during the study period. The results are discussed concerning the ecological importance of severe winters for benthic communities and the utility of our results for interpreting long-term changes.

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Section: Community Structurementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Cold winter effects on benthic macrofauna communities in near- and offshore regions of the North Sea

2006

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“…Benthic species in the shallow inner German Bight live in a very dynamic environment, characterised by large seasonal and annual temperature variations, storms and tidal currents that lead to sediment erosion and relocations (Dyer et al 1983;Dörjes et al 1986;Becker et al 1992;Kröncke et al 2001). Moreover, rare events such as extremely cold winters (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, rare events such as extremely cold winters (e.g. Ziegelmeier 1964;Dörjes et al 1986;Kröncke et al 1998;Armonies et al 2001) and anoxia (Niermann et al 1990;Duineveld et al 1991;Beukema 1992) affect significantly recruitment and survival of species. Further, benthic communities were changed by several anthropogenic impacts such as fishing disturbance, pollution, eutrophication and invasions by immigrant species, i.e., species that are intentionally or unintentionally introduced by human activity (e.g.…”

Section: Introductionmentioning

confidence: 99%

The fate of an immigrant: Ensis directus in the eastern German Bight

Dannheim

Rumohr

2011

Helgol Mar Res

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We studied Ensis directus in the subtidal (7-16 m depth) of the eastern German Bight. The jackknife clam that invaded in the German Bight in 1978 has all characteristics of a successful immigrant: Ensis directus has a high reproductive capacity (juveniles, July 2001: Amrumbank 1,914 m -2 , Eiderstedt/Vogelsand: 11,638 m -2 ), short generation times and growths rapidly: maximum growth rates were higher than in former studies (mean: 3 mm month -1 , 2nd year: up to 14 mm month -1 ). Ensis directus uses natural mechanisms for rapid dispersal, occurs gregariously and exhibits a wide environmental tolerance. However, optimal growth and population-structure annual gaps might be influenced by reduced salinity: at Vogelsand (transition area of Elbe river), maximum growth was lower (164 mm) than at the Eiderstedt site (outer range of Elbe river, L ? = 174 mm). Mass mortalities of the clams are probably caused by washout (video inspections), low winter temperature and strong storms. Ensis directus immigrated into the community finding its own habitat on mobile sands with strong tidal currents. Recent studies on E. directus found that the species neither suppresses native species nor takes over the position of an established one which backs up our study findings over rather short time scales. On the contrary, E. directus seems to favour the settlement of some deposit feeders. Dense clam mats might stabilise the sediment and function as a sediment-trap for organic matter. Ensis directus has neither become a nuisance to other species nor developed according to the 'boom-and-bust' theory. The fate of the immigrant E. directus rather is a story of a successful trans-ocean invasion which still holds on 23 years after the first findings in the outer elbe estuary off Vogelsand.

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“…Marine worms are not threatened or protected and some species are already used as bioindicators, such as the coastal lugworm Arenicola marina (Hannam et al, 2008). Arenicola marina are abundant and can be easily sampled at low cost, and it has been found that it can stand for as much as 20-30% of the total infauna biomass in sandy beaches (Dörjes et al, 1986). A. marina is not commercially important, but they are ecologically important organisms in benthic food webs and they be used as a biomarker for the Nordic area since there are indications that they may ingest plastic particles in the coastal areas from the Nordic area (preliminary data from Haave, 2016).…”

Section: Invertebratesmentioning

confidence: 99%