The British Isles
Nemertini
Oligochaeta
Polychaeta
Crustacea
Gastropoda
Lamellibranchia
Others
o
_.~.J
2
4
6
8
- I
__
J
10
Annual mean biomass (gm- 2 dry weight)
243
27
Fig. 8.6. Annual mean biomass (g m- 2 dry weight) of the various taxa from site 1 (no
algal cover, open bar) and site 2 (dense algal cover, shaded area) in Langstone Harbour,
south coast of England. Note that molluscs contribute most of the biomass at both sites;
bivalves (Lamellibranchia) are major contributors in open muds, whereas epibenthic
Gastropoda dominate the algal site (primarily Hydrobia ulvae). (After Nicholls et aI.
1981)
infauna such as Peloscolex benedini, Capitella capitata, Arenicola marina, Nereis diversicolor and epifauna such as Hydrobia ulvae and Littorina littorea (Goodwillie et al. 1970, unpubl.; Perkins and Abbott 1972;
Fahy et al. 1975; Anonymous 1976a; Soulsby et al. 1978;
Montgomery and Soulsby 1980; Nicholls et al. 1981; Soulsby et al. 1982;
Hull 1987; Jeffreyet al. 1992; den Hartog 1994; Figs. 8.5,8.6). The numbers of epifauna, and in particular Hydrobia, associated with the algal
mats are reported to be particularly high, quite significantly increasing
the faunal biomass at many of the sites (Anonymous 1976a; Montgomery
and Soulsby 1980; Soulsby et al. 1982; Montgomery et al. 1985; Fig. 8.6).
Nicholls et al. (1981), for example, found that 89% of the invertebrate
biomass on weed-covered areas comprised epifauna whereas 71 % of the
biomass on weed-free sites comprised infauna. They also found a tendency for bivalves to dominate open mudflats whereas gastropoda
(notably Hydrobia) dominated weed-covered areas (Fig. 8.6). It has been
suggested that this increase in both algal and faunal biomass can provide
an important food source for birds such as brent geese (Montgomery
and Soulsby 1980; Soulsby et al. 1982; Montgomery et al. 1985; Jeffrey
et al. 1992), However, Tubbs (1977) and Tubbs and Tubbs (1983)
concluded that the algal mats are generally detrimental to bird populations with some species avoiding areas with high algal cover (see also
Raffaelli et al. 1989).
Nemertini
Oligochaeta
Polychaeta
Crustacea
Gastropoda
Lamellibranchia
Others
o
_.~.J
2
4
6
8
- I
__
J
10
Annual mean biomass (gm- 2 dry weight)
243
27
Fig. 8.6. Annual mean biomass (g m- 2 dry weight) of the various taxa from site 1 (no
algal cover, open bar) and site 2 (dense algal cover, shaded area) in Langstone Harbour,
south coast of England. Note that molluscs contribute most of the biomass at both sites;
bivalves (Lamellibranchia) are major contributors in open muds, whereas epibenthic
Gastropoda dominate the algal site (primarily Hydrobia ulvae). (After Nicholls et aI.
1981)
infauna such as Peloscolex benedini, Capitella capitata, Arenicola marina, Nereis diversicolor and epifauna such as Hydrobia ulvae and Littorina littorea (Goodwillie et al. 1970, unpubl.; Perkins and Abbott 1972;
Fahy et al. 1975; Anonymous 1976a; Soulsby et al. 1978;
Montgomery and Soulsby 1980; Nicholls et al. 1981; Soulsby et al. 1982;
Hull 1987; Jeffreyet al. 1992; den Hartog 1994; Figs. 8.5,8.6). The numbers of epifauna, and in particular Hydrobia, associated with the algal
mats are reported to be particularly high, quite significantly increasing
the faunal biomass at many of the sites (Anonymous 1976a; Montgomery
and Soulsby 1980; Soulsby et al. 1982; Montgomery et al. 1985; Fig. 8.6).
Nicholls et al. (1981), for example, found that 89% of the invertebrate
biomass on weed-covered areas comprised epifauna whereas 71 % of the
biomass on weed-free sites comprised infauna. They also found a tendency for bivalves to dominate open mudflats whereas gastropoda
(notably Hydrobia) dominated weed-covered areas (Fig. 8.6). It has been
suggested that this increase in both algal and faunal biomass can provide
an important food source for birds such as brent geese (Montgomery
and Soulsby 1980; Soulsby et al. 1982; Montgomery et al. 1985; Jeffrey
et al. 1992), However, Tubbs (1977) and Tubbs and Tubbs (1983)
concluded that the algal mats are generally detrimental to bird populations with some species avoiding areas with high algal cover (see also
Raffaelli et al. 1989).