The distribution of 0‐group flatfish in relation to abiotic factors on the tidal flats in the brackish Dollard (Ems Estuary, Wadden Sea)

Abstract

The distribution of 0‐group flatfish was investigated in 1992 in the Dollard (Ems–Dollard estuary, Wadden Sea). 0‐Group plaice, flounder and sole were not evenly distributed over the sampled locations. The spatial distribution pattern of 0‐group flatfish in the Dollard changed during the investigation period. In the first week of sole presence, when the mean length of sole was 24–30 mm, salinity correlated significantly with sole density. The distribution of juvenile sole larger than 40 mm total length was affected by the elevation of the location: 0‐group sole was restricted to the sampled site with the lowest elevation. The distribution of 0‐group plaice was related to sediment: no juvenile plaice were caught at locations with more than 10% mud fraction in the sediment. The distribution of 0‐group flounder was also correlated with sediment. Later in the year, salinity correlated negatively with the distribution of 0‐group flounder. The influence of sediment composition is probably indirect and linked to the abundance of preferred food items, such as Corophium volutator. Abiotic conditions were suitable to 0‐group plaice, flounder and sole.

Sediment selection in juvenile plaice and its behavioural basis

“…The actual particle size varies between locations. Juvenile plaice avoided areas where the sediment has >10% of particles <16 m in the Ems estuary, Wadden Sea (Jager et al, 1993) and are most abundant where the sediment has a grain size of c. 140 m elsewhere in the Wadden Sea (Zijlstra, 1972). On the east coast of Scotland, 0-group plaice abundance correlates with median grain size over the range 200-400 m (Poxton & Nasir, 1985).…”

“…Flatfish (Pleuronectiformes) are uniquely adapted for a benthic lifestyle and substratum type is a major factor in determining their distribution (Burke et al, 1991;Rogers, 1991;Jager et al, 1993;Gibson, 1994Gibson, , 1997Wennhage & Pihl, 1994;Norcross et al, 1995;Abookire & Norcross, 1998;Mueter & Norcross, 1999). Their ability to select particular substrata has been tested in experiments where individuals are given a choice of sediments, the null hypothesis being that no preference is shown for any one sediment.…”

Feeding ecology and growth of age 0 yearPlatichthys flesus(L.) in a vegetated and a bare sand habitat in a nutrient rich fjord

“…Similar to many other flatfish species, juvenile flounder utilize shallow coastal areas as nursery grounds during their first few years (Gibson, 1994; Raffaelli & Hawkins, 1996). During this period juvenile flounder diets indicate a broad flexibility in prey choice as they include a wide variety of benthic invertebrates such as crustaceans, polychaetes and shelled prey such as bivalves and gastropods (Bregnballe, 1961; De Vlas, 1979; Summers 1980; Pihl, 1982; Kostrzewska‐Szlakowska & Szlakowski, 1990; Jager et al ., 1993; Aarnio et al ., 1996; Muus & Nielsen, 1998). This suggests that flounder are opportunistic feeders capable of adapting their feeding preferences to the prey assemblages of their environment.…”

Ecology of the whiskered sole in the Sado Estuary, Portugal

“…Low densities were recorded in autumn and winter and an increase in abundance in spring and summer was noticed. Similar abundance variation patterns have been reported for several Soleidae species, namely S. solea and S. senegalensis , that usually use estuaries as nursery areas (Marchand, 1988; Dorel et al ., 1991; Jager et al ., 1993; Cabral & Costa, 1999). The density values reported for these species for the winter period ( c .…”