Marine biodiversity patterns off Alexandria area, southeastern Mediterranean Sea, Egypt.

The biological marine system in the Mediterranean Sea off Alexandria, Egypt, was investigated to recognise its biodiversity and the relations among "ichthyofauna, invertebrates, and benthic" cover including biota and flora, as well as seabed bathymetry during 2017 using a multi-seasonal surveys by the commercial bottom trawler. Moreover, zooplanktonic community from the water column was also collected to support the picture of the biodiversity in the investigated area. The identified species were 94 fishes, 64 invertebrates, 6 benthic flora, and 304 zooplanktonic species. The ichthyofauna included 5 Chondrichthyes species (5.3% of the fish species), while Osteichthyes fishes were 89 species (94.7%) belonging to 48 families and 72 genera. The most abundant family was Sparidae (13 species). The highest abundance of fishes occurred in the summer (68 fish species 72.34%), while the lowest abundance occurred in the spring (49 species, 52.13%). Regarding the demersal and benthic biota, the most abundant phylum was Mollusca (31 species) and represented by three classes (Bivalvia, Cephalopoda, and Gastropoda). Gastropoda was the most abundant class (18 species), while the lowest Phyla was Chordata (1 species of Ascidians) and Annelida (1 species). The number of lessepsian fish species were 17 (18.1%) of the total number of species caught by the bottom trawl net. In addition, this work provided new records Aulopareia unicolor (F): Gobiidae) for the area for first time and considered the second time in Egypt. The benthic flora was represented by 6 species belonging to three phyla (Tracheophyta, Chlorophyta, and Rhodophyta). Sea grasses were represented by three species (Posidonia oceanica, Cymodocea nodosa, and Halophila stipulacea). The highest abundance of benthic species occurred in the summer (53 species with 75.7%), while the lowest one was in autumn (27 species, 38.6%). Geologically, the fishing ground constituted of hard rocks to very fine silt. The eastern part of the study area includes terrigenous Nile sediment origin, while the western side has biocalcareous sediment with shell fragments richness, coastal limestone ridges origin. The continental shelf, which runs along the study area, is portrayed by a 200-m contour line. In the water column, zooplanktonic community was represented by 304 taxa, belonging to 12 phyla, 6 phyla (Arthropoda, Tintinnida, Chordata "fish eggs and larvae", Cnidaria, Foraminifera, and Radiozoa) were dominant. Copepods were the dominant group (71.59%); its annual average abundance was 1271 ind./m3. Its most diversified season was the winter (175 No/m3.) and its average abundance was 1892.9 ind./m3. However, in spring, 118 species were recorded presenting the highest average abundance (2419.4 ind./m3). The lowest diversified season was summer (85 organisms) with density of 1150 ind./m3. The present work offers updated data regarding the marine biodiversity in Egypt, enriches the gaps in the bibliography in the Eastern Mediterranean, and gives preliminary list of species and biodiversity of bottom trawl combined with the interaction with other biosystems and features of fishing ground. These data could be used to monitor evaluate the impact of bottom trawl on the fisheries habitats and changing in ecosystems. Also, it could be used as constructive step to manage or protect such area in combination with other. It is recommended to fulfil the need for more and detailed studies in all areas by different gears to cover the gaps in marine biodiversity data.

Comparing genetic markers efficiencies for discrimination between two commercially important holothuroids in the Mediterranean Sea, Holothuria polii and Holothuria sanctori.

Sea cucumber (bche-de-mer, Echinodermata: Holothuroidea) is one of the top internationally traded seafood varieties. Besides its direct nutritional benefits, it is continuously used in the traditional medicine in different areas and cultures in the world. This world-wide interest triggered various issues related to stocks declining and risks of species extinction. For these reasons, the current study was designed to provide molecular tools for accurate discrimination between two sea cucumber species that prevail the Mediterranean of these echinoderms in Egypt, that are Holothuria polii and H. sanctori. The power of three gene markers, i.e., 16S rDNA, 28S rDNA, and Histone H3 in achieving accurate DNA-based identification, as well as elucidating clear phylogenetic and genetic diversity differences between those two species was assessed. Among the three genes, 16S rDNA showed the highest potentials as genetic and phylogenetic species discrimination marker. Both 28S rDNA and H3 exhibited the least number of holothuroid reference sequences in the GenBank database. For genetic diversity within each species population, 16S rDNA exhibited the best potentials, followed by H3. 28S rDNA showed no genetic polymorphism at all. Moreover, the collective data of both H3 and 16S rDNA suggested a possible role of asexual reproduction behavior in H. sanctori in the reduction of genetic diversity, as a possible response to overfishing. Hence, the current research can recommend the simultaneous application of both 16S rDNA and H3 as accurate markers for genetic discrimination among H. polii, H. sanctori and other different holothuroid species.

Spatiotemporal expression pattern of gonad-stimulating substance-like peptide of the sea cucumber, Apostichopus japonicus.

The spatiotemporal expression pattern of gonad-stimulating substance-like peptide-containing polypeptide (GSSLP) in the sea cucumber Apostichopus japonicus was examined using immunochemistry. The GSSLP was detected in the gonads from shortly before the empirical breeding season (May and June) to July. On the basis of immunoblotting analysis, GSSLP showed considerable polymorphism among the organs examined in this study, particularly in the gonads, in which the polymorphism was associated with N-glycosylation and the formation of intra-molecular disulfide bonds. In the ovary, GSSLP was expressed from March to June and corresponded to two bands at 113 and 100 kDa under reducing conditions. In July, only the larger band weakly remained. In testis, GSSLP was detected first in April as two bands of 245 and 190 kDa under reducing conditions. The number of bands increased to five in June but decreased to three smeared bands in July. In the radial nerve and circumoral nerve ring, GSSLP corresponded to a single peptide of 170 kDa with little N-glycosylation and its expression level hardly changed throughout a year with no correlation with the breeding season. GSSLP was detected mainly in the morula cells in all the organs examined. In addition, GSSLP was detected in the follicle cells of the ovary and, for a brief period, in the jelly space, but never in the ooplasm. In testis, the morula cells were localized close to the invaginated inner epithelium, but never in the male gametes. In July animals, gonadal morula cells were rarely observed.