Existing Monitoring Programmes
Given the lack of knowledge about true Sabellaria spinulosa
reefs (as opposed to annually forming thin crusts) one pressing priority is for detection
of their whereabouts and extent. In this regard, therefore, it is necessary to concentrate
on those beds found recently in the mouth of the Wash, in order to gain experience in
identifying and mapping them, as well as to satisfy monitoring requirements. Traditional
destructive sampling methods are of little use, and remote methods will need to be used.
However, recent experience has suggested that neither RoxAnnÔ
nor sidescan survey alone is as useful for mapping the extent of beds as might be expected
(Foster-Smith, pers. comm.). Sidescan was particularly disappointing as it failed to
distinguish clearly between Sabellaria spinulosa reef and nearby patchy hard
bottoms. RoxAnnÔ showed some potential for identifying likely
areas of Sabellaria spinulosa and for confirming suspected boundaries, but
groundtruthing, probably by a combination of video and diving, would be essential. ROV is
to be preferred over towed video, which will probably be damaging to the reefs, unless it
can be demonstrated that the damage incurred is likely to be negligible. The latter is
likely either if it can be demonstrated that recovery is rapid, or that the reef area is
very extensive and the areas damaged very small.
Information on recruitment to the beds would be important.
Unfortunately, given the strong stimulation to settle by adult S. spinulosa, and
the lack of settlement in its absence, settlement plates may be of little use. Unless
settlement plates can be shown to be worthwhile, recruitment would best be monitored by
investigating samples of reef. George & Warwick (1985) had little difficulty in
distinguishing early year classes in grab samples. Grab samples, unfortunately, are likely
to be very unreliable and damaging in the true reef areas and diver-obtained samples may
be required. A programme would need to be devised which would identify inter-annual
variation in recruitment.
Detailed methods for monitoring of the associated epifaunal community
can only be prepared once we have a clearer idea of what it is and how it functions.
However, much useful information on the large epifauna can probably be gained using diver
recording surveys for detailed areas and video recordings to study distribution of the
more conspicuous species over wider areas.
Existing Monitoring Programmes
The majority of licenses awarded for aggregate extraction contain
conditions. These include monitoring requirements although until recently these were
restricted to physical parameters. It is anticipated that biological monitoring associated
with a number of dredging operations will contribute to an understanding of the ecology
and monitoring of Sabellaria spinulosa (P. Gilliland, pers. comm.). Inclusion of
analysis of recruitment and population structure on a seasonal and interannual basis could
substantially increase the knowledge gained from such work.