A. Cattrijsse et al., NURSERY FUNCTION OF AN ESTUARINE TIDAL MARSH FOR THE BROWN SHRIMP CRANGON-CRANGON, Journal of sea research, 38(1-2), 1997, pp. 109-121
The brown shrimp Crangon crangon migrates into the brackish part of th
e Westerschelde estuary (southwest Netherlands) shortly after metamorp
hosis and uses the tidal marsh habitat as a nursery until reaching a t
otal length of about 15 mm. The importance of the marsh as a nursery w
as evaluated by estimating foraging activity, predation mortality and
residence time. In early postlarval stages, C. crangon utilised the in
tertidal creeks of an estuarine tidal marsh from (March-April) until l
ate autumn (October-November). Postlarval shrimp leaving the marsh wit
h the ebb tide always had significantly more food in their stomachs th
an shrimp entering the marsh with the incoming flood water. Predation
upon the shrimp population was relatively low during most months, but
it increased between August and October when common gobies, Pomatoschi
stus microps, were present in high densities. There was also predation
by the small seabass Dicentrarchus labrax. The marsh creeks function
both as foraging areas and as predation refuge. Depending on temperatu
re, postlarval shrimp stayed in the marsh for a period of two to three
weeks. Quantitatively, the value of the marsh as a nursery area had c
hanged drastically during a second year of sampling, illustrating high
natural year-to-year variability. However, the seasonal pattern remai
ned. Recruitment to the subtidal adult population represents an export
of animals from the marsh to the estuary. This export is negligible i
n terms of biomass (as compared to the total biomass of the estuarine
population) but it may be important in terms of numbers of individuals
.