Skip to main content Accessibility help

Algal-induced dislodgement as a cause of bivalve mortality on some Scottish beaches

  • A. D. Ansell (a1), L. Robb (a1) and H. T. Powell (a1)


During July 1984, large numbers of the sandy beach bivalve Donax vittatus (da Costa) were found either stranded in the intertidal, or washing to and fro in the surf on beaches at Dornoch, on the east coast of Scotland. The affected bivalves all carried large growths of several species of algae. The normal burrowing and recovery responses of the bivalves were unable to overcome the increased drag resulting from these epizoic algal colonies so that wave action caused dislodgement from the sand and eventually, stranding and death from dehydration. The resulting mortality affected mainly older individuals in the population; younger individuals had very small or no attached algae and were not dislodged.

The algal growths were complex and showed three stages in their development: primary settlements formed generally short tufts or mats attached to the posterior tip of die shell; secondary ‘dominant’ species were also attached to die shell but formed larger growths; tertiary species were attached as epiphytes to the primary and secondary growths. At least eight species of algae were involved. Juvenile mussels (Mytilus edulis L.) were also present in many cases attached to the weed, adding further to die drag.

During 1985, at Dornoch, secondary and tertiary algal species developed progressively from overwintering primary settlements, but the size of die algal colonies which developed was generally smaller dian in 1984 and diere was apparently little dislodgement and mortality.

Donax vittatus populations on other beaches in die Moray Firdi, and on most other Scottish beaches examined, had fewer individuals with attached algae, and diose affected carried only relatively small colonies which did not prevent normal burrowing. Complex algal colonies, showing even greater species diversity than those of Dornoch were, however, found on D. vittatus on beaches in South Harris, Outer Hebrides, during September 1984.



Hide All
Ansell, A. D., 1983. The biology of the genus Donax. In Sandy Beaches as Ecosystems (ed. McLachlan, A. and Erasmus, T.), pp. 607635. The Hague: Dr W. Junk Publishers.
Coe, W. R., 1955. Ecology of the bean clam Donax gouldi on the coast of Southern California. Ecology, 36, 512514.
Harris, J. E., 1943. Anti-fouling investigations, Section C in First Report of the Marine Corrosion Sub-Committee of the Corrosion Committee. Journal of the Iron and Steel Institute, no. 1, 405420.
Loesch, H. C., 1957. Studies of the ecology of two species of Donax on Mustang Island, Texas. Publications of the Institute of Marine Science, University of Texas, 4, 201227.
Mckay, D. W., 1972. Mass mortality of Donax vittatus (da Costa) at Sandend Bay, Banffshire. Conchologist's Newsletter, no. 43, 284285.
Nair, N. B. & Ansell, A. D., 1968. Characteristics of penetration of the substratum by some marine bivalve molluscs. Proceedings of the Malacological Society of London, 38, 179197.
Orton, J. H., 1929. Severe environmental mortality among Abra (= Syndesmya) alba, Donax vittatus and other organisms of the Lancashire coast. Nature, London, 124, 911.
South, G. R. & Tittley, I., 1986. A Checklist and Distributional Index of the Benthic Marine Algae of the North Atlantic Ocean. St Andrews (Canada) and London: Huntsman Marine Laboratory and British Museum (Natural History).
Stanley, S. M., 1970. Relation of shell form to life habits of the Bivalvia (Mollusca). Memoirs. Geological Society of America, no. 125, 296 pp.
Trueman, E. R., 1967. Activity and heart rate of bivalve molluscs in their natural habitat. Nature, London, 214, 832833.
Trueman, E. R. & Ansell, A. D., 1969. The mechanisms of burrowing into soft substrata by marine animals. Oceanography and Marine Biology, an Annual Review, 7, 315366.
Witman, J. D. & Suchanek, T. H., 1984. Mussels in flow: drag and dislodgement by epizoans. Marine Ecology - Progress Series, 16, 259268.


Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed