Stefanos Kalogirou

Diversity, structure and function of fish assemblages associated with Posidonia oceanica beds in an area of the eastern Mediterranean Sea and the role of non-indigenous species

Temporal and spatial variation in density, biomass and body size of littoral fish species associated with nearshore Posidonia oceanica meadows was studied over an annual cycle in an area of the eastern Mediterranean Sea. A total of 109,350 littoral fishes were collected, belonging to 34 families and 88 species. Density of fishes peaked during the summer due to high numbers of juveniles. Season was a significant factor determining density, although number of species and biomass did not show any obvious seasonal pattern. Throughout the study, schooling planktivorous fish species such as the picarel Spicara smaris, the bogue Boops boops and the damselfish Chromis chromis were dominant, both in terms of density (80%) and biomass (70%). Temporal variation in density and body size of fishes was used to assess the seasonal and ontogenetic habitat use of each species, with their affinity to seagrass assessed by comparing their respective distribution on sand. Four functional guilds were created (juvenile migrants, seagrass residents, seasonal migrants and occasional visitors) to describe the habitat use of P. oceanica meadows by each species. Several species associated with P. oceanica meadows used this habitat mainly as juveniles during summer, although many others were present concurrently as adults and as juveniles. Among the species encountered, 11 were non-indigenous of Indo-Pacific origin, of which three used seagrasses mainly as juveniles and four as residents. The non-indigenous silverstripe blaasop Lagocephalus sceleratus ranked among the 10 most dominant species in terms of biomass (2%) and was classified as a seagrass resident.

Feeding ecology of indigenous and non-indigenous fish species within the family Sphyraenidae.

The feeding ecology of two common indigenous (Sphyraena viridensis and Sphyraena sphyraena) and one abundant non-indigenous sphyraenid species, Sphyraena chrysotaenia, of Indo-Pacific Ocean origin, was investigated in an area of the eastern Mediterranean Sea. The stomach contents of 738 individuals of varying size, collected during the period December 2008 to August 2009, were examined. The dietary analyses revealed that all three species were specialized piscivores with a diet consisting of >90% fish, both by number and mass. Concurrent sampling of the fish assemblage made it possible to calculate selectivity as well as diet breadth and overlap of these strict piscivores. Even though several prey species were found in the stomachs of the three predators examined, selectivity towards Atherina boyeri was highly significant. For all species examined, >70% of the diet by mass was made up by three indigenous species of commercial value: Spicara smaris, Boops boops and A. boyeri. Diet breadth and size of prey increased with increasing body size for all predators. With increased body size, the diet overlap between indigenous and non-indigenous species decreased. This could be attributed to increased diet breadth and the specific life-history characteristics of indigenous species developing into larger individuals. During winter, the condition factor of the non-indigenous species was significantly lower than that of the indigenous, indicating that winter conditions in the Mediterranean Sea may limit its further expansion north and westward. With this study, the gap in knowledge of the feeding preferences of the most abundant piscivorous species found in coastal areas of the study region is filled. Additionally, the results indicate that non-indigenous species familial affiliation to indigenous ones does not facilitate invasion success.

The Ongoing Shift of Mediterranean Coastal Fish Assemblages and the Spread of Non-Indigenous Species

© 2012 Kalogirou et al., licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Ongoing Shift of Mediterranean Coastal Fish Assemblages and the Spread of Non-Indigenous Species

Genetics reveal the identity and origin of the lionfish invasion in the Mediterranean Sea

Following aquarium releases, invasive lionfishes have colonized large areas of the Caribbean and western Atlantic, resulting in an immense ecological damage. The early stages of that invasion are poorly known. Indeed, a lag of time between the introduction and detection often preclude genetic characterization of that crucial phase. With elevated awareness, the recent invasion of Pterois miles was quickly detected in the Mediterranean Sea. We hereby show that the very first individuals establishing populations in the Mediterranean Sea display haplotypes that nest within the large genetic diversity of Red Sea individuals, thus indicating an invasion via the Suez Canal. We also show that only two haplotypes are detected in the Mediterranean Sea, suggesting that few individuals may have been involved in the invasion. Thus, we conclude that the Mediterranean invasion is the result of a movement of individuals from the Red Sea, rather than from other means, and that low genetic diversity does not seem to have a negative effect on the success and spread of lionfish into the Mediterranean Sea.

First evidence of ingested plastics by a high commercial shrimp species (Plesionika narval) in the eastern Mediterranean

This study provides the first evidence of nylon filament occurrence in the stomach of an economically important target shrimp species in the Mediterranean Sea, Plesionika narval (Fabricius, 1787). Samples were collected monthly from November 2014 to October 2015 from shallow (10-30 m) and deeper waters (150-170 m). The occurrence of plastics in the stomachs of the Narwal shrimp was 5.93% and identified as Nylon by FT-IR analysis. Higher percentages of ingested plastics were found in females from shallower depths and in males from deeper waters. The maximum number of plastics was recorded in January and March, possibly related to the higher feeding intensity of females prior to their reproduction period. A total of 10.3% of females and 4.8% of males with ingested plastics had almost empty stomachs. The presence of plastics in the stomach of P. narval is an evidence of passive ingestion which in this study related to fishing activities.

Participatory management in a high value small-scale fishery in the Mediterranean Sea

the Mediterranean Sea Christos D. Maravelias*, Paraskevas Vasilakopoulos, and Stefanos Kalogirou Institute of Marine Biological Resources and Inland Waters, Hellenic Centre for Marine Research, 46.7 km Athens-Sounio Ave., Anavyssos 19013, Greece Unit D.02 Water and Marine Resources, European Commission, Joint Research Centre, Directorate D—Sustainable Resources, Via Enrico Fermi 2749, 21027 Ispra, VA, Italy Institute of Marine Biological Resources and Inland Waters, Hellenic Centre for Marine Research, Hydrobiological Station of Rhodes, Cos street 1, Rhodes 85100, Greece *Corrresponding author: tel: þ306938951252; fax: þ302109811713; e-mail: cmaravel1@gmail.com.

Africa-Arabia Connections and Geo-Archaeological Exploration in the Southern Red Sea: Preliminary Results and Wider Significance

We report on a preliminary exploration of the submerged landscapes in the Saudi Arabian sector of the southern Red Sea aboard the Hellenic Centre for Marine Research (HCMR) Research Vessel, AEGAEO, in May–June 2013. The survey sampled areas of the continental shelf down to the shelf margin at ~130 m depth in the vicinity of the Farasan Islands and combined high resolution acoustic techniques with sediment coring to reconstruct features of the now-submerged landscape of potential archaeological significance, including geological structure, topography, palaeoenvironment, and sea-level change. The region is currently of wide interest and significance: to archaeologists because it is currently regarded as one of the primary pathways of dispersal for early human populations expanding out of Africa during the Pleistocene, in which the extensive but now-submerged shelf region may have played a key role; and to marine geoscientists because the Red Sea offers unusual opportunities as a ‘laboratory’ for investigating Pleistocene sea-level change. Preliminary results indicate that the submerged landscape was characterised by a complex topography with fault-bounded valleys and deep basins, some of which may have hosted, at least intermittently, fresh water during periods of lowered sea level.