5.3 Settlement and Dispersal of Macrofauna
135
5.3.3
Development of Spatial and Temporal Patterns by Initial Settlement
and Secondary Dispersal
Initial settlement of benthic macrofauna is mainly determined by two factors: (I)
active substrate selection and (2) hydrodynamics (Butman 1987). According to this
author both factors may co-occur in the same species but function on different
spatial scales. Thus, for soft sediments such as those investigated in ELA W A T
(Groninger Plate and Swinnplate, see Figs. 3.1.3 and 3.1.4) the place of initial
settlement results from a combined effect of species specific behaviour and local
hydrodynamics.
The benthic assemblages in the sandt1ats of the Groninger Plate were dominated
by polychaetes. For most polychaete species, general data on settlement, recruitment and secondary dispersal are sparse or completely lacking.
Table 5.3.1 Objectives of the investigations carried out from 1994-96 for the studied species.
The location of the sampling stations is given in Fig. 3.1.2
1994
1995
1996
Period of
beginning of April
end of April until the
end of April until
investigation
until middle of Sepmiddle of August,
middle of September,
tember
one additional samone additional sampling in December
piing each in January
and March
Lanice consmall and large-scale
settlement experieffects of the ice
chilega
distribution of initial
ments
winter
settlers
comparison of two
adult habitats
Heteromastus
large scale distribution large scale distribution
{iliformis
of initial settlers
of initial settlers
Scoloplos
initial settlement,
armiger
small scale variability
Macoma
year class strength of
initial settlement.
initial settlement,
halthica
initial settlement,
secondary dispersal,
secondary dispersal,
secondary dispersal,
2-4 stations
2-4 stations
2-5 stations
Ensis amerisecondary dispersal,
initial settlement,
initial settlement,
canus
2-5 stations
secondary dispersal,
secondary dispersal,
2-4 stations
2-4 stations
Cerasloderma
initial settlement,
initial settlement,
edule
secondary dispersal,
secondary dispersal,
2-4 stations
2-4 stations
Mya arenaria
initial settlement,
initial settlement,
secondary dispersal,
secondary dispersal,
2-4 stations
2-4 stations