A preliminary study on the effects of oyster culturing structures on birds in a sheltered Irish estuary
This study investigated the species composition, numbers and behaviour of birds in an intertidal oyster culture area in Cork Harbour. These data were compared to a nearby area free of aquaculture within the same estuary in March 1999. Species which occurred in the aquaculture free area were also observed in the trestle-area. The most abundant species were oystercatcher Haematopus ostralegus, redshank Tringa totanus, dunlin Calidris alpina, curlew Numenius arquata, black-headed gull Larus ridibundus and common gull Larus canus. Oystercatcher, curlew, black-headed gull and common gull occurred in significantly lower numbers in the trestle area, while for redshank and dunlin the differences were not significant. The percentage of birds feeding did not differ between the two areas. Oystercatcher, redshank, dunlin and curlew mostly fed in both areas. In contrast, black-headed gull and common gull generally did not feed, but surveyed the area. Whether the trestles were covered by oyster bags or not did not have any effect on the number of birds except for the dunlin. Dunlin were significantly more frequent beneath the trestles with bags compared with those without bags. In general, the percentage of birds feeding did not differ between areas. Interspecies differences occurred with regard to the position occupied by birds at the trestles. Oystercatcher, redshank and curlew spent more time underneath the trestles. Dunlin, black-headed gulls and common gulls did not differ in numbers underneath or on top of the trestles. These preliminary observations at a single time period give some insight as to the potential interactions between shellfish aquaculture and intertidal birds.
Key wordsshellfish aquaculture trestles birds feeding behaviour oysters estuary Ireland
Unable to display preview. Download preview PDF.
- Brosius, G. & F. Brosius, 1995. Base System and Professional Statistics. Thomson, Bonn, 1002.Google Scholar
- De Grave, S., Moore, S. J. Burnell, G. 1998. Changes in benthic macrofauna associated with intertidal oyster, Crassostrea gigas (Thunberg) culture. J. Shellfish Res. 17: 1137–1142.Google Scholar
- Gibbons, D. W., Reid, J. B., Chapman, R. A. 1993. The new atlas of breeding birds in Britain and Ireland: 1988–1991. T & A. D. Poyser, London.Google Scholar
- Hutchinson, CD. 1989. Birds in Ireland. T. & A.D. Poyser Ltd., Calton, Staffordshire, UKGoogle Scholar
- Kaiser, M. J., Laing, I., Utting, S. D., Burnell, G. M. 1998. Environmental impacts of bivalve mariculture. J. Shellfish Res. 17: 59–66.Google Scholar
- Martin, P. & P. Bateson, 1986. Measuring Behaviour. Cambridge University Press, Cambridge: 1200.Google Scholar
- Nugues, M. M., Kaiser, M. J., Spencer, B. E. & Edwards, D. B. 1996. Benthic community changes associated with intertidal oyster cultivation. Aquacult. Res. 27: 913–924.Google Scholar
- Shepherd, R. (1993) Ireland’s Wetland Wealth. The Irish Wildbird Conservancy. Dublin, Ireland.Google Scholar
- Smiddy, P., O’ Halloran, J., Coveney, J. A. Leonard, P. G. Shorten, M. 1995. Winter waterfowl populations of Cork Harbour: an update. Irish Birds 5: 285–294.Google Scholar
- Yates, M.G., Goss-Custard, J. D., McGrorty, S., Lakhani, K. H., Le V. Dit Durell, S. E. A., Clarke, R. T., Wispin, W. E., Moy, I., Zates, T., Plant, R. A., Frost, A. J. 1993. Sediment characteristics, invertebrate densities and shorebird densities on the inner banks of the Wash. J. appl. Ecol. 30: 599–614.CrossRefGoogle Scholar