A. Minchin et D. Minchin, DISPERSAL OF TBT FROM A FISHING PORT DETERMINED USING THE DOGWHELK NUCELLA-LAPILLUS AS AN INDICATOR, Environmental technology, 18(12), 1997, pp. 1225-1234
Ireland was the first country to introduce a legislative ban in April
1987 on the usage of organotin antifouling paints, this included tri-b
utyl-tin (TBT). Vessels under 25 metres were not permitted to use thes
e substances because of harmful effects to shallow water sea inlets. T
he ban prevented use of organotins on most fishing vessels and pleasur
e craft. TBT causes a condition, imposer, resulting in sexual impairme
nt in neogastropods. This condition was examined in the dogwhelk Nucel
la lapillus at 66 stations in Bantry Bay, SW Ireland, to determine dis
persal from source from the main input areas. Highest imposer levels w
ere recorded in the harbour of the fishing port Castletownbearhaven. H
igh levels of TBT in sediments and use of TBT antifouling paints by th
e fishing fleet have resulted in reductions of dogwhelk abundance at t
he harbour entrance. Nearby, dogwhelks had high levels of imposer, whi
ch declined with distance from source. The lower frequency of imposer
observed elsewhere within Bantry Bay may be due to residual flow of wa
ter through the Bay and periodic exchanges with shelf water from an ar
ea of upwelling off the bay entrance. A gradual recovery of the area w
ould be expected if the ban on TBT usage were applied to vessels of le
ss than 50m.