DISTRIBUTION AND HABITAT PREFERENCES OF THE INTRODUCED MUMMICHOG FUNDULUS-HETEROCLITUS (LINNEAUS) IN SOUTH-WESTERN SPAIN

The distribution and apparent habitat preference of the common mummich og (Fundulus heteroclitus) in south-western Spain were examined during summer-autumn 1996. This introduced species was more or less continuo usly distributed along the Atlantic coast of Spain, being more abundan t in sites near the coastline (usually <10 km inland), mainly in four extensive marshes. The species preferred marsh-related mesohabitats, s uch as salt lagoons, saltmarsh fish ponds and marsh channels, both nat ural and man-modified. Fundulus heteroclitus was mostly found at salin ities >25. It was the most frequently captured fish species, occurring at 81 of the 272 sites sampled; their frequency of occurrence was alm ost twice that of the second ranked species (Gambusia holbrooki). Howe ver, in over 80% of cases, F. heteroclitus was found alone or with onl y one sympatric fish species, which usually belonged to a group compos ed of Gobius niger, mugilids, Anguilla anguilla, Blennius sp., Lebias ibera, Pomatoschistus sp. and Dicentrarchus labrax. Finally, the origi n and dispersal of mummichog in the Iberian peninsula and the potentia l effects of this species on native fish populations is discussed. (C) 1998 Academic Press Limited.