A. Cattrijsse et al., NEKTON COMMUNITIES OF AN INTERTIDAL CREEK OF A EUROPEAN ESTUARINE BRACKISH MARSH, Marine ecology. Progress series, 109(2-3), 1994, pp. 195-208
The utilization of an estuarine brackish marsh in the Westerschelde es
tuary (southwest Netherlands) by fish and crustaceans visiting the int
ertidal creeks at rising tides was investigated over an 18 mo period.
Samples were collected every month over a tidal cycle. A stow net pass
ively fished the nekton migrating in and out of the marsh habitat. Sim
ultaneous measurements of current speed and waterheight allowed for qu
antification of the catches. Multivariate clustering and ordination te
chniques were applied to assess temporal changes in the nekton assembl
age. A total of 68 fish and crustacean species were caught but only 38
were regular visitors of the marsh creek. The marsh nekton community
proved to have a very stable character. Only 40% of the observed varia
nce could be explained. The seasonal appearance of juvenile stages of
fish and crustaceans was found to differentiate between spring and sum
mer-autumn communities. The environmental variables measured (i.e. tem
perature, salinity, oxygen concentration and detritus standing stock)
did not correlate well with the observed changes in community structur
e. The mysid shrimp Neomysis integer dominated the community, both in
density and biomass, during most of the year. Early postlarval flounde
r Pleuronectes flesus characterized the spring nekton assemblage. Earl
y postlarval brown shrimp Crangon crangon was abundant from spring thr
ough autumn. In late summer juveniles of seabass Dicentrarchus labrax,
common goby Pomatoschistus microps and shore crab Carcinus maenas wer
e typical members of the marsh creek nekton. The hyperbenthic fauna of
the marsh was comparable to the hyperbenthos found in the adjacent su
btidal parts of the Westerschelde estuary while the epifauna of both a
reas differed substantially. It is argued that the marsh under study i
s a nursery ground for only a small number of estuarine inhabitants: C
. crangon, P. flesus, C. maenas, P. microps, D. labrax and possibly 2
mullet species. Adult flounder, adult and juvenile common goby, juveni
le seabass and the early postlarval brown shrimp all use the creeks as
feeding ground, mainly preying upon the creek infauna and mysids. Giv
en the high abundance of hyperbenthic mysid shrimp in the marsh and th
eir presumed role in detritus-based food chains, we believe marsh stud
ies should not refrain from considering this component of the nekton.
This is the first study reporting on the nekton use of a European mars
h. The need for similar research in other European marshes is stressed
.