Experimental assessment of oyster transfers as a vector for macroalgal introductions

Type Article
Date 2007-06
Language English
Author(s) Mineur Frederic1, Belsher Thomas2, Johnson Mark P.1, Maggs Christine A.1, Verlaque Marc3
Affiliation(s) 1 : Queens Univ Belfast, Sch Biol Sci, Belfast BT9 7BL, Antrim, North Ireland.
2 : IFREMER, F-34203 Sete, France.
3 : Univ Aix Marseille 2, COM, DIMAR, UMR 6540, F-13288 Marseille, France.
Source Biological Conservation (0006-3207) (Elsevier), 2007-06 , Vol. 137 , N. 2 , P. 237-247
DOI 10.1016/j.biocon.2007.02.001
WOS© Times Cited 49
Keyword(s) Elimination treatments, Transport, Marine macrophytes, Thau Lagoon, Shells, Crassostrea gigas, Biological invasions
Abstract Introduction of non-indigenous species can alter marine communities and ecosystems. In shellfish farming, transfer of livestock, especially oysters, is a common practice and potentially constitutes a pathway for non-indigenous introductions. Many species of seaweeds are believed to have been accidentally introduced in association with these transfers, but there is little direct evidence.
We experimentally simulated the transfer of oysters from the Thau Lagoon (France). These transfers involved increasing periods of aerial emersion and additional brine and hot water treatments. The brine and hot water treatments were evaluated as a means of reducing the probability of algal introductions with oyster transfers. Shells were cultured for 40 days in experimental tanks to identify the macroalgae likely to be introduced with any oyster transfer.
A total of 57 macroalgal taxa, including 16 taxa not indigenous to the Thau Lagoon, were recorded across all treatments and experiments. The abundance of some species increased in several cases following aerial emersion. Elimination treatments (immersion in brine or hot water) significantly reduced algal diversity, with hot water treatments resulting in no species or only tubular Ulva spp. present.
The results support the hypothesis that oyster transfers are effective as primary and secondary vectors of macroalgal introductions. Relatively simple changes to the transfer practice (particularly hot water treatments) are suggested as a means of reducing the risk of non-indigenous algal introductions.
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