IMIS

The influence of tidal, neap, spring and day night cycles on the feeding behaviour of the common goby Pomatoschistus microps was investigated in a creek of a salt marsh in the brackish zone of the Westerschelde estuary. Effects of tidal cycles were assessed using samples taken on 16, 17 and 19 August 1994. A stow net was used for collecting the samples. Sampling was conducted over several tidal phases. On each occasion sampling started when water began to flood the creek. After slack water the net was turned around to sample the ebb current. The net was hauled every one hour. It was observed that most of Pomatoschistus microps entered the creek during the first hour of the tidal cycle and left the creek during the last two hours of ebb. Feeding activity was highly influenced by tidal stimuli (tidal cycle and neap-spring tides). There was no significant difference between the feeding activity of fish caught during day time and at night and neap and spring tides had an influence on the feeding pattern of fish. The amphipod Corophium volutator was the most important prey. This amphipod had a high contribution to the diet both in terms of numbers and biomass. The mysid Mesopodopsis slabberi was also important. Neomysis integer, Nereis diversicolor and Crangon crangon were taken infrequently but due to their high biomass, contributed significantly to the total diet. Calanoid copepods were eaten very frequently but were unimportant in terms of biomass.