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Table 1. Preliminary checklist of macro algal species recorded on loggerhead turtles in the western Mediterranean Sea. The study which first documented the species is given.

It has been proposed that the western Mediterranean Sea contains loggerhead turtles from two discrete nesting populations: 1) the southeastern USA/Gulf of Mexico and 2) the eastern and central Mediterranean Sea (Margaritoulis 1982; Márquez 1990). Genetic (Bowen et al. 1993; Laurent et al. 1993), tagging-recapture (Bolten et al. 1992; Manzella et al. 1988) and fisheries-based studies (Camiñas 1992; 1995; Camiñas & Serna 1995) have probed the dual origin of these loggerhead turtles.

The area surrounding the Balearic Islands is considered an important loggerhead feeding area, particularly during spring and summertime (Camiñas 1997). The Spanish longline fleet incidentally captures large numbers of loggerhead turtles, and during 1998-2002 the Spanish Institute of Oceanography (IEO) conducted an onboard observer programme of this fishery. Complementary to this activity, a study of the loggerhead epibiotic algae was undertaken. During the onboard period a total 131 samples of algae were obtained and preserved from the 676 loggerhead turtles captured. The incidence of algae on the loggerhead was 64 % in 1999 and 69.1 % in 2000. The analysis of the total 131 samples is underway.

Our study compliments three previous studies in the region (Báez et al. 2001; Frazier et al. 1985, Gramentz 1988). The epizoic macroalgae growing on loggerhead turtle in the western Mediterranean Sea are shown in Table 1. The algae we found growing on loggerhead turtles were small and filamentous (Báez et al. 2001). To date only 5 species and 2 taxa (these only to level of genus) have been recorded on Mediterranean loggerheads. This is in contrast to 33 species and 4 taxa described in Abel Sentíes et al. (1999) for the loggerhead from the western Atlantic Ocean. These are the first records of Seirospora sphaerospora and Ectocarpus fasciculatus growing on loggerhead turtles.

The implications of the presence of Polysiphonia carettia on the biogeography of loggerhead turtles in the Northern Hemisphere has been discussed in Báez et al. (2001). The authors investigated the possibility of using Polysiphonia carettia as a biological marker to distinguish the loggerheads that come from the Atlantic Ocean to those coming from the eastern Mediterranean Sea. Additional studies on Polysiphonia distribution are underway to test this hypothesis.

Acknowledgements: We are grateful for the constructive review of two anonymous referees.

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