Expansion of the macroalga Caulerpa racemosa and changes in softbottom macrofaunal assemblages in Moni Bay, Cyprus

The recent expansion of the Red Sea macroalga Caulerpa racemosa and its impact on the diversity and abundance of macrobenthos were examined and compared in the summers of 1992 and 1997, in Moni Bay, Cyprus. The phytobenthic community of the bay in 1992 was dominated by the seagrass Posidonia oceanica while, in 1997, the Lessepsian migrant C. racemosa became the most dominant, forming extensive mars. Changes in the vegetation system in Moni Bay have caused significant compositional changes in macrofaunal assemblages. A total of 178 individuals of 62 species are recorded. The composition of the macrofauna in 1992 was dominated by gastropods (44 %), crustaceans (22 %), bivalves (17 %), polychaetes (11 %) and echinoderms (6 %). In 1997, the gastropods and crustaceans had decreased to 13 % and 16 % respectively, while, polychaetes had increased to 38 % becoming the mast dominant taxon. Bivalves and echinoderms also increased to 22 % and 11 %, respectively, in 1997. The proliferative growth of C. racemosa imposed successional changes on the macrofaunal assemblages in Moni Bay, Cyprus, between 1992 and 1997. It remains to be tested whether the expansion of C. racemosa is related to the increase of water temperature associated with global warming or nutrient inputs or with the differences in the life history characteristics of this migrant vs. native algal species.L'expansion récente de la macroalgue de mer Rouge Caulerpa racemosa et son impact sur la diversité et l'abondance du macrobenthos ont été comparés dans la baie de Moni, à Chypre, entre les étés 1992 et 1997. La communauté phytobenthique de la baie était dominée en 1992 par l'algue Posidonia oceanica, alors qu'en 1997, l'immigrant lessepsien C. racemosa dominait, formant de vastes prairies. Les changements de végétation dans la baie de Moni ont entraîné des modifications significatives dans la composition de la macrofaune. Au total, 178 individus de 62 espèces ont été examinés. La composition de la macrofaune était dominée en 1992 par les gastéropodes (44 %), les crustacés (22 %), les bivalves (17 %), les polychètes (11 %) et les échinodermes (6 %). En 1997, les gastéropodes et les crustacés étaient réduits à 13 et 16 % respectivement, tandis que le polychètes devenaient le taxon dominant (38 %) ; les bivalves et les échinodermes progressaient également jusqu'à 22 et 11 % respectivement. La croissance proliférante de C. racemosa a provoqué une série de changements dans la macrofaune de la baie de Moni entre 1992 et 1997. Il reste à établir si l'expansion de C. racemosa est due à l'élévation de la température de l'eau associée au réchauffement global, à l'apport des nutriments, ou aux différences entre les caractéristiques de l'évolution de cet immigrant et celles des espèces algales indigènes

Molecular resolution of marine turtle stock composition in fishery bycatch: A case study in the Mediterranean

Based on an extensive sampling regime from both nesting populations and bycatch, frequency analyses of mitochondrial (mt) DNA control region haplotypes in the Mediterranean were used to assess the genetic structure and stock composition of the loggerhead sea turtle, Caretta caretta, in different marine fisheries. The analyses show the following. (i) In drifting longline fisheries working in Mediterranean pelagic habitats 53-55% of turtles caught originated from the Mediterranean stock; (ii) In bottom-trawl fisheries all turtle bycatch is derived from this regional stock; (iii) This regional stock contribution to fishery bycatch suggests that the population size of the Mediterranean loggerhead nesting population is significantly larger than previously thought. This is consistent with a recent holistic estimate based on the discovery of a large rookery in Libya. (iv) Present impact of fishery-related mortality on the Mediterranean nesting population is probably incompatible with its long-term conservation. Sea turtle conservation regulations are urgently needed for the Mediterranean fisheries. (v) The significant divergence of mtDNA haplotype frequencies of the Turkish loggerhead colonies define this nesting population as a particularly important management unit. Large immature and adult stages from this management unit seem to be harvested predominantly by Egyptian fisheries. (vi) Combined with other data, our findings suggest that all the nesting populations in the Mediterranean should be considered as management units sharing immature pelagic habitats throughout the Mediterranean (and possibly the eastern Atlantic), with distinct and more localized benthic feeding habitats in the eastern basin used by large immatures and adults. (vii) Between the strict oceanic pelagic and the benthic stages, immature turtles appear to live through an intermediate neritic stage, in which they switch between pelagic and benthic foods