| Remarks |
Abstract:
The biology of Echinus esculentus was investigated at various depths throughout a four-year period, using a permanent array of transect lines. Although numbers of urchins declined during the study period, the pattern of vertical distribution remained very stable. At a depth of 15 m, which is the lower boundary of the Laminaria zone, the density of Echinus reached 4 m−2, but both within and below the Laminaria forest the numbers fell abruptly to < 1 m−2. The evidence suggests that settlement is most successful at 15 m, where habitat structure and water movements combine to give optimal conditions. Elsewhere silting or unsuitable habitat is limiting. Growth rates were comparable to results obtained elsewhere in the British Isles. |