Buccinum undatum L. in the North Sea, state of whelks and imposex phenomena

• Published in: Marine environmental research 1995, Vol.39 (1), p.354-355
• Main Authors: Ten Hallers-Tjabbes, Cato C., Boon, Jan P.
• Format: Article
• Language: English
• ISSN: 0141-1136; 1879-0291
• DOI: 10.1016/0141-1136(95)98403-Y

During the Integrated North Sea Programme (Microcontaminants (INP-MICON, September-October 1991, May-June 1992)) the state of the whelk, Buccinum undatum L. was investigated. B. undatum is a predatory gastropod that mainly preys on bivalves. The animal lives in and on top of the sediment, is relatively long-lived and lives in a confined area, which becomes more confined as the eggs, deposited on hard-substrate objects on the sea floor, hatch into young snails. Distribution of whelks at the investigated locations and phenomena of imposex were used as indicators of the state of the whelk. Whelks were also collected for neurosensory experiments that are now in a pilot stage. No live whelks could be caught at the stations close to shore. At most of these locations many empty and hermit-inhabited whelks were caught, indicating that live whelks had dwelled here in the past, an observation that is supported by data from earlier inventories. Live whelks, when caught, were more abundant at the Northern stations and at the Western most stations in the central North Sea than at stations closer to shore. Imposex phenomena did occur in some female whelks, which showed tiny or somewhat bigger penis homologues. At some Northern most stations no imposex phenomena occurred. At the other Northern stations the phenomena were smaller and the incidence was lower than in the central and southern North Sea. The highest rates of imposex in the central and southern North Sea coincided with the vicinity of shipping lanes. The imposex rates were higher in the more densely shipped routes than in the less busy north-south deep water route. The station "Brucey's Garden" a supposed reference area in the northern North Sea, that showed somewhat elevated incidence of imposex, appeared to be situated in a relatively more intensely used shipping area than the Dogger Bank, where only one minor imposex phenomenon was found. The levels of tributyltin (TBT) and its metabolites, dibutyltin (DBT), and monobutyltin (MBT), were measured in whelks from the first leg of the cruise. TBT was not detectable, but DBT and MBT were, albeit at low levels. At the only station where all females showed imposex, DBT and MBT levels were twice as high as in the other stations where DBT and MBT were detectable. Metabolization of TBT in Buccinum undatum may differ from that in Nucella lapillus, the snail in which imposex was clearly related to elevated levels of TBT in animals and environment. Laboratory experiment