Factors promoting marine invasions: A chemoecological approach

Abstract

The Mediterranean Sea is losing its biological distinctiveness, and the same phenomenon is occurring in other seas. It gives urgency to a better understanding of the factors that affect marine biological invasions. A chemoecological approach is proposed here to define biotic conditions that promote biological invasions in terms of enemy escape and resource opportunities. Research has focused on the secondary metabolite composition of three exotic sea slugs found in Greece that have most probably entered the Mediterranean basin by Lessepsian migration, an exchange that contributes significantly to Mediterranean biodiversity. We have found toxic compounds with significant activity as feeding deterrents both in the cephalaspidean Haminoea cyanomarginata and in the nudibranch Melibe viridis. These findings led us to propose aposematism in the former and dietary autonomy in producing defensive metabolites in the latter case, as predisposing factors to the migration. In the third mollusk investigated, the anaspidean Syphonota geographica, the topic of marine invasions has been approached through a study of its feeding biology. The identification of the same compounds from both the viscera of each individual, separately analyzed, and their food, the seagrass Halophila stipulacea, implies a dietary dependency. The survival of S. geographica in the Mediterranean seems to be related to the presence of H. stipulacea. The initial invasion of this exotic pest would seem to have paved the way for the subsequent invasion of a trophic specialist that takes advantage of niche opportunities.Lessepsian migration ͉ defense ͉ Opisthobranchia ͉ resource opportunities

Biofouling on artificial substrata in Muscat waters

“…Interestingly, invasive tunicate C. intestinalis was not recorded in this part of the world (Therriault and Herborg 2008). Invasive species decrease biodiversity of indigenes communities and have serious impacts on fisheries and aquaculture (Mollo et al 2008). Most of invasive species spread by ballast waters or by biofouling on ship hulls (Gollasch 2002).…”

Biogeographical homogeneity in the eastern Mediterranean Sea - I: the opisthobranchs (Mollusca: Gastropoda) from Lebanon

“…Unfortunately, not much information is available on biotic factors determining the ability of the alien opisthobranch species to invade new regions. According to Mollo et al (2008), who studied three well known and established Mediterranean invaders (Haminoea cyanomarginata, S. geographica and Melibe viridis), selective dietary requirements (to obtain protective chemicals) may act as limiting factors to the migration of alien opisthobranch species, while the non-selective nature of their feeding habits, related to the ability to biosynthesise de novo defensive metabolites, represents a predisposing factor for colonizing new environments. This strongly suggests that only the most 'efficient' species may be able to invade, and this would also explain the low number of confirmed alien opisthobranchs recorded in the Mediterranean Sea (~ 30) relative to the total number of ca.…”

Carbon self‐utilization may assist Caulerpa taxifolia invasion

“…(Box et al 2009;Casu et al 2009), this can be associated with physiological effects, suggesting that ingestion is incidental in some cases (Box et al 2009). Some species (e.g., sea slugs) have mechanisms to avoid effects of, and even exploit, algal toxins (Mollo et al 2008), but colonization by these species may represent a change in community assemblage following Caulerpa spp. invasion.…”