The Scheldt Informationcenter: an information platform for the estuary of the River Scheldt

The Scheldt InformationCenter acts as an information platform for the estuary of the River Scheldt. This center is active in both Flanders and The Netherlands. Its area of interest concerns the tide-related part of the River Scheldt, information about the estuary area at the disposal of everybody interested in thesubject.Additionally, the institute acts as a contact point. The Scheldt InformationCenter contributes also in popularising less accessible reports and publications and has therefore an interface function between the public authorities, the scientific community and the public at large. Coordinating Scheldt-related projects is another task of the institute. In all activities, the different functions of the estuary, safety, policy and management are central issues.By informing everybody about the River Scheldt, the institute hopes to enlarge the involvement and public awareness of this estuary, a river so important for Sealand (NL) as well as Flanders (B)

Tidal and diurnal periodicity in macrocrustaceans and demersal fish of an exposed sandy beach, with special emphasis on juvenile plaice <i>Pleuronectes platessa</i>

Macrocrustaceans and juvenile demersal fish were sampled in spring of 1997 in the surf zone of an exposed sandy beach on the Belgian coast. Three consecutive 24 h cycles were sampled to investigate tidal, diurnal and semi-lunar distribution patterns within the epibenthic community. Multivariate statistical techniques and 3-way ANOVA were used to evaluate the effects of the environmental variables measured. The most important variable correlated with the variation in epibenthic catch density was the state of the tide (ebb and flood), but light intensity (day and night) was also important. The individual catch density of several species differed significantly over the three 24 h cycles. Despite the strong turbulent conditions of the site studied, clear tidal (e.g. the brown shrimp Crangon crangon, juvenile plaice Pleuronectes platessa) and diurnal (e.g. juvenile sole Solea solea and clupeids, caught mainly during the night/day respectively) periodicities of many macrocrustacean and demersal fish species were observed. Nevertheless, the extremely turbulent conditions of the surf zone possibly affect the behaviour of many species (e.g. juvenile brown shrimp are not able to bury themselves as the water retreats). To investigate whether the high dynamics of the surf zone suppress the ability of juvenile plaice to actively search for food, stomach contents were analysed. Also, the interaction with potential prey was investigated: the hyperbenthic fauna was sampled simultaneously and macrobenthic data were available from the literature. Clearly, the Belgian sandy beaches are used as a feeding ground by I-group plaice. An opportunistic utilisation of available food resources is suggested. I-group plaice migrate high up the beach during the flood tide to profit from the rich macrobenthic intertidal area, while the 0-group feeds mainly on the most abundant hyperand macrobenthic organisms from somewhat deeper water. The presence of the 0-group in the intertidal area is possibly linked to refuge for predators or influenced by the strong surf zone currents