|Kelp, sea urchins and predators: a review of strong interactions in rocky subtidal systems of eastern Canada, 1970-1980|
Mann, K.H. (1982). Kelp, sea urchins and predators: a review of strong interactions in rocky subtidal systems of eastern Canada, 1970-1980. Neth. J. Sea Res. 16: 414-423
In: Netherlands Journal of Sea Research. Netherlands Institute for Sea Research (NIOZ): Groningen; Den Burg. ISSN 0077-7579, more
Abundance of the sea urchin Strongylocentrotus droebachiensis increased following reduced predation pressure, and dense kelp (Laminaria and Agarum) beds were overgrazed and destroyed along more than 500 km of coastline in Nova Scotia, Canada. During the same period of time, lobster stocks in this area were reduced to about 10% of their former level. Whilst direct evidence is lacking, indirect evidence suggests very strongly that the population explosion of urchins was triggered by a reduction of lobster stocks below a critical level, and that subsequent destruction of kelp beds caused increased lobster mortality through loss of cover, and reduced production in the food chain supporting the lobsters. The whole comprises a positive feedback leading to further decreases in lobster stocks and the present, low-productivity configuration of urchin-dominated barren grounds.