The sensitivity of S. spinulosa to man induced change was
summarised in a recent report (Holt et al., 1997a). This section draws heavily on that
Berghahn & Vorberg (1993) have suggested that Sabellaria spinulosa
in its absence is a good indicator of fishing intensity in the Wadden Sea.
Subtidal S. spinulosa reefs are reported to have been lost due to physical damage
in at least five areas of the north east Atlantic. In the Waddensee, Riesen & Reise
(1982) reported that extensive subtidal S. spinulosa reefs were lost from the
Lister Ley, island of Sylt, between 1924 and 1982; they reported that local shrimp
fishermen claimed to have deliberately destroyed them with "heavy gear" as they
were in the way of the shrimp trawling. Reise & Schubert (1987) reported similar
losses from the Norderau area, and attributed them to similar causes. Shrimp trawling
still occurs in these areas and the S. spinulosa have not reappeared, but have
effectively been replaced by mussel Mytilus edulis communities and assemblages of
sand dwelling amphipods (Reise & Schubert, 1987). The mussels are also exploited.
Dorjes (1992) reported complete loss by 1987 of almost two km2 of Sabellaria
spinulosa reef in Jade Bay, North Sea, the distribution of which had been described by
Schuster (1952, ref not seen), and suggested that this was probably as a result of
In Morecambe Bay fisheries for pink shrimp Pandalus montagui
have been implicated in the loss of subtidal Sabellaria spinulosa reefs in the
approach channels to the Bay (Mistakidis, 1956; Taylor & Parker, 1993). EU LIFE funded
surveys in appropriate areas during May 1998, using grabs, small beam trawls and anchor
dredges, as well as interview with local divers, found no evidence of Sabellaria
spinulosa, although there were numerous pink shrimp, and some subtidal S. alveolata
were found adjacent to known intertidal reefs (Fletcher, pers. comm.).
Warren & Sheldon (1967), discussing the pink shrimp fishery of the
Thames Estuary and the Wash, reported that "it has been the accepted practice among
commercial fishermen to search with a small hand dredge for the polychaete worm Sabellaria
spinulosa and then trawl for shrimp in areas where this was found." Warren (1973)
reported "In recent years ross (Sabellaria spinulosa) has been found only in
small clumps in the Wash where the bottom is predominantly sandy, particularly towards the
offshore end of the fishery. No reefs of ross are known to exist."
Graham (1955) assumed that trawling would damage Sabellaria
spinulosa reefs but did not back this up with any direct evidence. He also assumed
that recovery would be rapid as the worms were effectively annual.
Rees & Dare (1993), using a four point numerical scale of
assessment of "risk of extinctions through natural and anthropogenic factors"
for a number of benthic species, considered that the risk for S. spinulosa from
trawl/dredge effects was high, scoring the maximum 4.
Clearly it is certain that at least in the short term Sabellaria
spinulosa reefs would suffer severe direct damage by extensive aggregate dredging
activities, and that aggregate extraction is very likely to occur in areas where S.
spinulosa is found, as expected from the distribution and habitat requirements of the
species. This has been noticed in practice by English Nature and others (e.g. various
licensed dredging areas, Gilliland pers. comm.; East Anglia, Attrill pers. comm.). The
extent of important Sabellaria reef structures, and speed of recovery from this
damage, are presently unknown. Compared to fishing impacts, gravel extraction is likely to
be more limited in extent, more controlled, and less likely to continue for very long time
periods, so that although direct damage would obviously be severe, recovery from adjacent
undamaged areas seems more likely. The likelihood of damage due to sediment plumes in
areas adjacent to gravel extraction is presently less clear, since there is no knowledge
of the effects of differing particle sizes upon Sabellaria, for example, although
it would be surprising if damage was other than very localised given the preference for
somewhat turbid waters.
Sabellaria spinulosa appears to be generally tolerant of changes in
water quality. Hoare & Hiscock (1974) investigated the distribution of marine
organisms around the outfall from a bromide extraction plant in North Wales. The effluent
had a pH of 4 and among other contaminants contained free halogens. Species richness and
diversity was markedly reduced within 150 m of the outfall both intertidally and
subtidally, with red algae, Antedon bifida and Helcion pellicidum being
particularly sensitive. However, S. spinulosa was found closer to the outfall than
any other organism, and was found in larger numbers at intermediate distances than further
away. Hoare & Hiscock (1974) also reported that other workers had described S.
spinulosa as a pollution indicator but unfortunately did not give relevant references.
Furthermore, in a report on surveys of Dublin Bay in relation to sewage
discharge and dumping, Walker & Rees (1980) reported that "In the dumping area
and in the south-east of the bay downtide of the dump site, where depths are greater, the
faunas resembled the Nucula/Sabellaria [spinulosa] community of Caspers. As
well as having pollution indicator species, this latter community generally had greater
faunal densities and diversities than elsewhere in the bay (except low diversities at the
dump sites in 1971). Apart from a possible effect of depth, this suggests that the dumping
was having an enriching rather than a degrading effect, although the probable sediment
change since 1874 may imply a change in community type".
S. spinulosa was relatively unaffected by an outfall containing
free halogens (see 3. Water Quality, above).
The only other information found was the following work on oil
dispersants. Larvae of Sabellaria spinulosa were killed after several weeks in a 1
ppm concentration of an oil dispersant (detergent BP1002) while larvae in uncontaminated
control experiments all survived (Wilson, 1968a). A 2.5 ppm concentration killed the
larvae within a day or two. Since the toxicity of detergents varies enormously and no
other species were tested, it is not known whether this represents a strong sensitivity to
such chemicals on the part of S. spinulosa or not. Further experiments using
heavier concentrations suggested that detergent adsorbed onto the sand particles forming
the tubes of S. spinulosa and caused the death of larvae settling onto them, but
that the effects lasted only a few days (Wilson, 1968c). No studies on the effects of oil
or oil and detergent mixes were found, nor on more modern detergents.
Overall S. spinulosa seems unlikely to show any special
sensitivity to chemical contaminants.