Effects of A Toxic Bloom of Chrysochromulina Polylepis on the Common Dog-Whelk, Nucella Lapillus on the Swedish West Coast

• Published in: Journal of the Marine Biological Association of the United Kingdom
• Main Author: Robertson, Annika
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 1991
• Subjects: Aquatic Science; Dog whelk; Nucella lapillus
• Online Access: http://dx.doi.org/10.1017/s0025315400053157; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0025315400053157

A massive toxic bloom of Chrysochromulina polylepis occurred along the Swedish west coast in May and June 1988 with severe effects on most biota in shallow marine habitats. In the present study, the effects on the common dog-whelk, Nucella lapillus was investigated in the archipelago at the mouth of the Gullmar Fjord. Mortality varied throughout the archipelago, with extinction of populations in the inner parts and survivors found only on the outermost islands. Even on these sites, mortality could be as high as 98­99%. Extensive samples of survivors and dead animals were divided into five age groups dependent on size and wear of the shell. The cohort consisting of 3­4 year old individuals suffered the lowest mortality, while mortality was almost total in younger and older cohorts. In each age group, except the oldest, survivors were significantly larger than the dead. The number of egg capsules laid per female in 1988 seemed normal, but about half of the capsules were empty. The number of young per capsule was significantly lower in 1988 compared to 1989, but the young were significantly bigger.