Galeus melastomus is the most common Pentanchidae in the Mediterranean Sea. A scavenger and opportunistic feeder, and despite the wide distribution, little is known about its feeding habits in Italian waters. The main purpose of this study was to investigate the diet of the blackmouth catshark by analysing the stomach contents. The specimens analysed were obtained from five populations of the Tyrrhenian and of the Ionian Seas, collected from a depth between 40 and 700 m. A total of 259 stomachs were analysed. The stomach contents were grouped into macro-categories and identified to the lowest taxonomic level possible. Crustaceans such as Parapenaeus longirostris, the Cephalopods Heteroteuthis dispar and Onychoteuthis banksii, and Osteichthyes, mostly Myctophidae, were identified. Plastic debris was also found among the stomach contents and classified according to its colour and shape. Osteichthyes represent the most abundant item (44%), above all the Myctophidae family, except for the catshark population from Tuscany, in which the most frequent species were Cephalopods, such as Abralia veranyi and Heteroteuthis dispar. Differences in the plastic debris contents were also observed between the Tuscany population and other populations. These could be explained as a probable consequence of the different depths at which the blackmouth catshark populations were sampled.
The pearl oyster Pinctada imbricata radiata (Leach, 1814), from the Pacific Ocean, was one of the first species to reach via Suez the Mediterranean, colonizing the eastern basin and recently spreading to the western. The species showed to be able to adapt to a wide range of climatic, hydrological, and ecological conditions. Since 2000 it reached the Strait of Messina, where is now infesting the transitional waters of the oriented natural reserve “Laguna di Capo Peloro.” Due to such resistance and adaptation ability, various assays were performed. Haemocyte morpho‐functional aspects were evaluated in haemolymph samples fixed with 1% and 2% glutaraldehyde for optical and electron microscopy (TEM). The following assays were carried out: cell characterization using several dyes, detection of intra‐ and extracellular lipids, the capability of phagocytosis using the yeast Saccharomyces cerevisiae and to produce superoxide anion (O2−). Detection of several enzymes, such as acid and alkaline phosphatase, arylsulfatase, chloro‐acetylesterase and β‐glucuronidase was also assessed. Cell count was demonstrated to be abundant with a mean of 8.263 × 106 mm2 ± 0.935 × 106 (SD). Two main cell populations were noticed: granulocytes and hyalocytes, both competent for phagocytosis, to produce O2−, and characterized by lipids. Based on the granule analysis, enzymatic activity was also demonstrated. The observations under TEM confirmed all the results obtained. This study supports the hypothesis that P. imbricata radiata can be usefully employed as a model organism in environmental biomonitoring. Moreover, since the species represent potential threats to native species and ecosystems, further insights into its biological adaptations in invaded ecosystems are recommended.
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