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and non-patch samples respectively (Figure 8.1(iv)). They were practically absent
from both sample types during the following August.
The numbers of C. edule dramatically rose in P. elegans patches during August 1998
to very high densities of 114 ± 11.5 per core (Figure 8.1(v)). This is far greater than
the numbers in patches the same time the previous year (16.7 ± 1.5 per core)
suggesting that the spat-fall of 1998 and/or juvenile survival was possibly higher than
the previous year. A similar trend was shown by M. balthica, whose densities within
P. elegans patches rose from 2.67 ± 0.88 per core in August 1997 to 18.5 ± 1.4 per
core in August 1998 (Figure 8.1(vi)).
Corophium volutator was found almost exclusively in P. elegans patches, with mean
densities between 5-6 per core from April to December 1997, but was totally absent in
August 1998. Oligochaetes were present in relatively low numbers from April to
August 1997, but peaked in abundance in non-patch samples (6.0 ± 2.25 per core) in
December 1997. Although present in August 1998, oligochaetes were not sufficiently
abundant for statistical analysis.
These results suggest that for the majority of the most abundant taxa, significantly
higher densities were attained in P. elegans patches than outside patches, at least at
certain times of the year. For example, significantly higher densities of C. capitata
(April, 1997; Figure 8.1(iv)); C. edule (April and August, 1997 and August 1998;
Figure 8.1(v)); M. balthica (December 1997 and August 1998; Figure 8.1(vi)); and C.
volutator (April to December 1997; Figure 8.1(vii)) were found in P. elegans patches
compared to outside patches. Furthermore, this pattern was also shown by the
meiofauna. Although not counted, harpacticoid copepods and nematodes were much
more abundant on the 212[tm sieve fractions from patches compared with those from
non-patch samples.
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