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Five marine sponges were collected from six stations from the Levantine Basin in the vicinity of Alexandria city, Egypt (Spongia sp., Cinachyrella sp., Ciocalypta penicillus, Axinella verrucosa, and Plakortis simplex).The antibacterial activities against seven pathogenic bacteria; Aeromonas hydrophila, Staphylococcus aureus ATCC 6538, Pseudomonas aeruginosa ATCC 8739, Vibrio damsela, Bacillus cereus, Streptococcus faecalis and Escherichia coli, were done. The results showed that the acetone extract of Spongia sp. had a broad spectrum and was the most effective against A. hydrophila (AU= 32.1). It was followed by ethanol extract (AU= 25.5). Ciocalypta penicillus and A. verrucosa showed higher antibacterial activity against E. coli, where AUs were 17.4, 17.4 and 16.0 for ethanol, acetone, and methanol extracts, respectively. All extracts treated by trypsin and boiling, completely lost their bioactivities except in some cases, the bioactivities decreased to low levels. The ethanol extract of C. penicillus lost about 64.4% of AU against E. coli. Also, the methanol extract of A. verrucosa lost about 56.4% of AU against E. coli. The GC-MS patterns confirmed that several substances could be easily affected by proteases and temperature, such as fatty acids and their derivatives. Steroids (digoxigenin) and terpenoids (?-Carotene betulin, astaxanthin, and rhodopsin) were also estimated to be among these extracts.

In this study we investigated the phylogenetics of two sea urchin species, Arbacia lixula and Paracentrotus lividus from the Mediterranean Sea. Specimens were collected from the east coast of Alexandria City, Egypt. Pigmentation examination showed four sympatric color morphotypes (black, purple, reddish brown, and olive green). Mitochondrial DNA was extracted from specimens and mitochondrial cytochrome oxidase subunit I (COI) and 16S ribosomal RNA (16S) were sequenced. The results showed that all black specimens constituted the species A . lixula . All other colors belonged to P . lividus , with no apparent differentiation between color morphotypes. Moreover, P . lividus showed high haplotype diversity (COI; H = 0.9500 and 16S; H = 0.8580) and low values of nucleotide diversity (COI; π = 0.0075 and 16S; π = 0.0049), indicating a high degree of polymorphism within this species. This study represents the first attempt at DNA barcoding of echinoid species in the southeast Mediterranean off the Egyptian coast, and will provide a base for future phylogenetic analyses.

This study is concerned with the variability in abundance, size composition and benthic assemblages of two echinoid species, the common sea urchin Paracentrotus lividus (Lamarck, 1816) and black urchin Arbacia lixula (Linnaeus, 1758) in the Southeastern Mediterranean (SEM) along the coast of Alexandria, Egypt. Four seasonal trips were made during the years 2014–2015 covering 55 km of the shore with depths ranging between 3 and 9 m. The sea urchin species composition, density and size structure and distribution were compared. The associated macrobenthic invertebrates with prominent presence and biomass were observed as well as other benthic fauna and flora associations. The present results showed that P. lividus was the dominant echinoid spatially and temporally. A. lixula showed frequent occurrence in Sidi Bishr and Sidi Gaber stations in the spring season. The most dominant size class was the medium to large-sized classes for P. lividus and large-sized classes for A. lixula. The commercial size for the edible P. lividus represented 33% of the sampled population. Furthermore, the most dominant macrobenthic assemblages beside the echinoid population were primarily oysters, sea cucumbers, and mussels. Beside these, assemblage of seaweeds (red, green, brown and crustose algae), Porifera, Cnidaria, Crustacea, other Echinodermata, Bivalvia, Gastropoda, Tunicata, Bryozoa and Annelida were found. The present study shows that the investigated area represents stable habitats for the echinoid population with rich and diversified algal assemblages as well as other potential food resources.

For many years the sea urchin (Echinodermata: Echinoidea) diversity and habitat in the Mediterranean Levantine basin lacked complementary data despite the critical role they have as keystone species to any marine ecosystem. As the first step of the present study two stations were selected along the Alexandria coast for investigation. These two stations are the Miami area and the Abou Qir Bay. Around 200 individuals were collected monthly from each station from April 2012 till April 2013 using Scuba diving. A comparison between the two stations was done that included a comparison between the inhabiting sea urchin community and the present associated macrobenthic fauna and flora. The results showed a great similarity between the two stations in relation to the sea urchin species present in these two areas as well as the surrounding habitat. This study aims to combine the morphology tool and the molecular tool along with data gathered from the habitat of the sea urchin present in these two stations to clear uncertainties in species identification of the sea urchin community found off the coast of Alexandria. The results showed four apparent morphologically different sea urchin specimens. To ensure our findings DNA extraction and Polymerase Chain Reaction (PCR) methods were used where the amplified 16S mitochondrial DNA products from all four sea urchin groups showed four sets of bands with different sizes which suggest that these four groups of sea urchins might be of four different species. Furthermore, the morphological characters along with the resulting DNA bands cleared uncertainties about two species the Paracentrotus lividus (Lamarck, 1816) and the Arbacia lixula (Linnaeus, 1758). The other two sea urchins that were thought to be Psammechinus microtuberculatus (Blainville, 1825) and Sphaerechinus granularis (Lamarck, 1816), remained unclear in identification and this requires further biological and genetic studies.