Observations on an aggregation of the starfish Asterias rubens L. in Morecambe Bay,Lancashire, England

Summary

In the summer of 1976 a narrow, band-shaped aggregation of the starfish Asterias rubens occurred on widespread subtidal beds of Mytilus edulis in Morecambe Bay, Lancashire. Distribution of starfish along the band, which was moving towards the intertidal, was patchy and greatest densities occurred at the leading edge of the aggregation. In dense patches less than 50% of the starfish were actively feeding. The size distribution of the starfish was unimodal. Potential factors leading to the irregular summer season aggregations of A. rubens associated with superabundant food such as mussels are discussed. Observations on the scavenging whelk Buccinum undatum in the starfish aggregation are compared with observations from an area where there were fewer starfish.