Sermin Açik

Spatio-temporal distributions of zoobenthos in Mersin Bay (Levantine Sea, eastern Mediterranean) and the importance of alien species in benthic communities

Abstract Spatio-temporal variations of soft-bottom zoobenthic communites in Mersin Bay were examined at seven stations between February and October 2009. A total of 337 species were encountered, of which Polychaeta had the highest number of species (136 species), and Mollusca possessed the highest number of individuals (65% of total specimens) and biomass (59% of total biomass). The highest benthos density (max. 9760 ind. m−2) and biomass (max. 133 g m−2) were found at shallow-water stations, whereas the highest diversity index values were calculated at the deepest station. The molluscs Cerithidium diplax, Corbula gibba and Bittium reticulatum dominated the area. Changes of zoobenthic communities were spatial rather than temporal and were strongly correlated with depth and the sediment structures. A total of 40 alien species were found in the area, of which 15 species were possibly transported to the area by ships and the others were Lessepsian migrants. The most domiant alien species in the area were C. diplax, Finella pupoides, Notomastus mossambicus and Amphiodia obtecta. Alien species formed dense populations at shallow water stations, and accounted for 12% of total number of species and 31% of total number of individuals in the area. The community parameters estimated for alien species significantly differed among stations but not among sampling periods. The main factors negatively affecting the number of alien species and individuals were depth, the clay percentage and total organic carbon concentration in sediment. The number of native species and individuals in the area show moderate positive correlations with those of aliens.

Annelids (Polychaeta and Oligochaeta) from the Sea of Marmara, with descriptions of five new species

This paper deals with annelids (Oligochaeta and Polychaeta) collected in the Sea of Marmara between 2006 and 2010 at depths from 0 to 66 m. A total of five oligochaete and 198 polychaete species were found. Five polychaete species, namely Prosphaerosyllis marmarae sp. nov., Levinsenia demiri sp. nov., Levinsenia kosswigi sp. nov., Levinsenia marmarensis sp. nov. and Levinsenia tribranchiata sp. nov. are new to science, and five oligochaete and 84 polychaete species are new to the fauna of the Sea of Marmara. A list of species found in the region and their maximum densities are presented at depth intervals. The present material includes six alien polychaete species, Paraprionospio coora, Polydora cornuta, Prionospio (Minuspio) pulchra, Pseudopolydora paucibranchiata, Chaetozone corona and Metasychis gotoi, of which the latter four species were new records for the region.

Macrobenthic fauna associated with the invasive alien species Brachidontes pharaonis (Mollusca: Bivalvia) in the Levantine Sea (Turkey)

The invasive alien mytilid species, Brachidontes pharaonis , forms a biogenic habitat in the mediolittoral and upper-infralittoral zones of the Levantine Sea, hosting a number of alien and native species. Examinations of samples taken from dense, continuous mussel beds at seven stations along the coast of northern Levantine Sea yielded 187 macro-benthic invertebrate species belonging to 11 taxonomic groups. Polychaeta accounted for 46% and 37% of the total number of species and individuals, respectively. The top three dominant species in the mussel beds were Stenothoe gallensis, Spirobranchus kraussi and Mytilaster minimus . The species with the highest frequency values on the mussel beds were Pseudonereis anomala, Phascolosoma stephensoni and Elasmopus pocillimanus . The highest density and biomass of the associated fauna were estimated as 42,550 ind m −2 and 1503 wwt g m −2 , respectively. The species number in samples varied between 14 and 47 species. The environmental variables best explaining variations in zoobenthic community structures were salinity, dissolved oxygen and total inorganic nitrogen in the water column. The biotic indices, TUBI and ALEX, classified the ecological status of one or two stations as moderate or poor, based on the relative abundances of ecological and zoogeographic groups, respectively. A total of 21 alien species were found to be associated with the mussel bed, of which Syllis ergeni is being newly considered as a new established alien species for the Mediterranean Sea. The maximum density of associated alien species was calculated as 30,300 ind m −2 . The alien species assemblages were greatly affected by salinity and total inorganic nitrogen.