How different is Mediterranean Caulerpa taxifolia (Caulerpales: Chlorophyta) to other populations of the species?

Abstract

The green macroalgal species Caulerpa taxifolia is indigenous to tropical/subtropical Australia, ranging as far south as 28° and 29° 15′ S on the Australian mainland east and west coasts, respectively. The origin of disjunct populations of the species, discovered in 2000 on the Australian mainland east coast at localities to 35°S remains unknown, variously attributed to introduced exotic strains or range extensions from other eastern Australian populations. Some naturally occurring Australian populations of C. taxifolia are similar to Mediterranean C. taxifolia. In Australia, large broad forms of the species, which have been known in the region since 1860, grow luxuriantly in sheltered seagrass meadows, with some of these populations tolerating minimum surface seawater temperatures in winter of 12.5 to 14.5°C. Accordingly, the contention that the Mediterranean has been invaded by a genetically-modified, large, cold-adapted strain of C. taxifolia may be incorrect. It is crucial that genetic markers (DNA fingerprinting, microsatellites) sensitive at the population level are used to accurately determine the genetic relatedness of C. taxifolia populations.