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

Abstract

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.

New Mediterranean Biodiversity Records (June 2012)

“…The Mediterranean parrotfish (Sparisoma cretense L. 1758) is more common in the south and eastern parts of the Mediterranean Sea and its typical distribution range has been historically dictated by the February 15°C surface isotherm barrier. In Greece, it is incidentally caught in rocky shores up to 50 m depth mainly in the Dodecanese (Petrakis & Papaconstantinou, 1990;Kalogirou et al, 2010;Kalogirou et al, 2012), in the Kyklades islands (Stergiou et al, 2002) and in Kriti (Katsanevakis & Thessalou-Legaki, 2009). Up to now there has been no record of it from the Ionian Sea.…”

Ecological characteristics of the invasive pufferfish Lagocephalus sceleratus (Gmelin, 1789) in the eastern Mediterranean Sea – a case study from Rhodes

“…The mesh size of the gear decreases from the outer end of the wing towards the centre with the sequence 500, 180, 32-34, 12, and 11 mm, with minimum mesh size of 5-8 mm at its cod-end. For further details, see Kalogirou et al (2010Kalogirou et al ( , 2012. Three samples using the seine were taken randomly at each location and sampling occasion.…”

“…The social impacts are obvious due to toxicity but the ecological impacts can only be supported with quantitative data. In the study area (Rhodes), L. sceleratus has become well established since its first record in 2005 (Corsini et al, 2006), but its ecology has only been touched recently (Kalogirou et al, 2010;Minos et al, 2010;Aydin, 2011;Kalogirou et al, 2012).…”

Morphological Studies on the Gills of Puffer Fish (Lagocephalus sceleratus, Gmelin, 1789)

“…More importantly, L. sceleratus is considered to be a serious hazard to consumers since it contains a strong marine toxin called tetrodotoxin (TTX), which can be lethal to humans. Another important negative impact of L. sceleratus is related to complaints from local fishers that have become frequent in Egypt, Lebanon, Cyprus, Turkey and Greece where the destruction of nets due to attacks by L. sceleratus that can easily cut lines and nets using its strong teeth (Kalogirou et al, 2010). Also, it attacks fishes caught in nets and lines of fishers leading to reduction of local stocks of squids and octopus through predation (Nader et al, 2012).…”