Distribution

Recruitment

Associated Communities

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.

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.

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