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On 14th October 2021, a single specimen of Sargocentron caudimaculatum was captured in the locality of Cape Bon, Eastern Tunisia, by a local fisher using gillnets at 60 m depth, on rocky bottom. This observation represents the first record of this species in the Mediterranean Sea. General information on the squirrelfishes and the importance of molecular tools for the proper identification of morphologically challenging non-indigenous organisms were raised and discussed.

Epifaunal communities associated with the fan shell Pinna nobilis Linnaeus, 1758 along the Tunisian coastline were investigated. Both univariate and multivariate analysis were done at different spatial scales within five populations located at different localities, three from northern and two from eastern Tunisia. The size of Pinna did not appear as the main factor affecting the structure of the associated biota, which seemed to be more influenced by (a) marine-lagoon and (b) biogeographic gradients. Patterns of similarity of sessile sclerobionts and motile epifauna were clearly different. The former assemblage best replied to lagoon-sea gradient and to locality, with three real clusters at 40%, whereas the latter assemblage scattered widely in a non-metrical MDS plane, with two real clusters only at 20% similarity. The spatial turnover of motile species was ten times higher than that of sessile species at a small spatial scale, being less affected by Pinna size, and three times higher though invariant at a large geographic scale. On the other hand, β-diversity of sessile species appeared to be more influenced by latitudinal (climatic) gradient at a large scale, being higher in the northern than in the eastern communities. Analysis of taxonomic (dis)similarity of the whole community detected these two sources of environmental (lagoon-sea gradient) and biogeographic (lati-longitudinal gradient) variation, although each phylum showed its peculiar pattern. In terms of Dajoz’s constancy index the majority of associated communities were dominated by rare species, and within the majority of epifaunal assemblages, the most abundant sessile epizoobiont was a bivalve mollusc. The sessile epifauna was dominated by active filterers, which led to a possible existence of trophic competition between the host and the sedentary epizoites, since both basibionts and sclerobionts occupy the same trophic niche. The fan shell played an important ecological role, providing new hard substrate to colonise, increasing the spatial heterogeneity for the surrounding soft-bottom communities, and contributing to the overall increase of the local biotope complexity level.

The Australian spotted scyphomedusaPhyllorhiza punctatawas recorded for the first time in Tunisian waters in August 2012, in the lagoon of Bizerte (Tunisia). Metaephyrae and juveniles occurred simultaneously in August 2012. The occurrence of adult medusae was detected from September to November 2012, and from August to October 2013. This is the second record of a reproducing population ofP. punctatain the Mediterranean Sea. The low abundance of mesozooplankton in summer and autumn 2012 coincides temporally with the highest density ofP. punctatarecorded in the lagoon, suggesting that predation by this alien jellyfish may have been a limiting factor for the mesozooplankton abundance on site. [ABSTRACT FROM PUBLISHER]

Cymbula nigra is the largest limpet in the Mediterranean. It has been listed since 1993, as an 'endangered species'. Its historical range in the Mediterranean includes the southern Spanish, the Moroccan and the Algerian coasts. Recent observations have confirmed its proliferation in southern Spain and its progression along the European and North African Mediterranean coasts. Field surveys carried out along the Tunisian coasts during winter 2011 revealed the presence of this species in the Gulf of Tunis and the Cap Bon. The finding of C. nigra represents a range extension possibly enhanced by the current global warming, as it is a 'warm-water species'. The absence of records in previous surveys to the same sampling sites (2006-2007), together with the small sizes recorded in 2011, confirms the recent installation of the species. The limpet was recorded in areas spared of pollution, characterized by a predominant influence of the Atlantic current, and also showed a preference for steep cliffs exposed to strong waves. This is the first population study of this endangered gastropod outside of its original range of distribution. The determination of the ecological characteristics of newly colonized habitats might serve as a starting point for the establishment of appropriate recommendations for its conservation. [ABSTRACT FROM AUTHOR]

The present study aims to explain the breeding strategies adopted by the dolphinfish Coryphaena hippurus Linnaeus, 1758, on the basis of biometric data combined to the study of microscopic ovarian and testicular structures, made on samples accumulated over two years, and a periodic and regular monitoring of landings. The dolphinfish is a gonochoric species, whose oocyte development is of asynchronous type, since in period of reproduction the ovarian structure is quadrimodal with the simultaneous presence of all types of oocytes: primary, previtellogenic, vitellogenic and ova. Confirmed by the evolution of the gonadosomatic index and the ovarian biometrics, this observation allows to conclude that this species reproduces in Tunisian waters and is characterized by repeated and spread spawning from May to September [ABSTRACT FROM AUTHOR]

Abstract: This study attempt to quantify and identify skeletal deformities in natural populations of Aphanius fasciatus collected from the Tunisian coast and tends to found a possible relationship between these anomalies and several types of pollutants presents in the environment. Fish were collected from one reference area (S1: coast of Luza) and three polluted areas (S2: industrialized coast of Sfax, S3: coast of Khniss and S4: Hamdoun’Oued). Various patterns of skeletal deformities were diagnosed using double staining technics, and the levels of heavy metals (Cd, Cu and Zn), various polycyclic aromatic hydrocarbons (PAHs) and estrogenic compounds were determined in water and sediment from different sites. Spatio-temporal variation of the spinal deformities frequencies in A. fasciatus show that high incidence of spinal anomalies has been recorded in population collected from S2 in comparison to three other ones. Morphological results indicated that skeletal deformities of adult A. fasciatus were grouped into 13 categories that described abnormalities on spines, vertebrae, arcs and mandibles. A total of 1025 abnormalities were quantified. The results of chemical analysis showed that the levels of heavy metals and PAHs were significantly higher in S2 than in S1, S3 and S4. High level of estrogenic activity was observed only in S4. A possible correlation between environmental exposures to a mixture of pollutants in coastal waters in S2 and spinal deformities in A. fasciatus was suggested. [Copyright &y& Elsevier]

Abstract: A microsporidian of the genus Spraguea was found parasitizing the nervous tissues of Lophius piscatorius collected from various localities in the Mediterranean coastal areas of Tunisia. The tissue localization, the infection focus aspect and sporal dimorphism are characteristics of Spraguea lophii species. Molecular data based on partial sequence of SSUrRNA encoding gene shows few nucleotide polymorphisms, compared to all described Spraguea isolates. Molecular karyotype obtained on pulsed field gel electrophoresis (1D-PFGE) shows a profile with 14 stained bands in the range of 230–880kbp and a genome size estimated to 6.700kbp. The rare cutter endonuclease MluI KARD 2-D-PFGE fingerprint shows an extensive chromosome length polymorphism, but the number of chromosome is unchanged and consists of 15 different molecules. The extensive chromosome length polymorphism is associated to a reduced number of genetic events. [Copyright &y& Elsevier]

To investigate the possible influence of the Siculo-Tunisian Strait on the genetic structure of white seabream Diplodus sargus, 13 polymorphic allozyme loci and a fragment of the cytochrome b mito-chondrial DNA were analysed. Allozyme data indicated a moderate but significant differentiation between some north-eastern (Bizerta, Ghar El Melh Lagoon and Mahdia) and southern (Gabes Gulf and El Biban Lagoon) samples. This heterogeneity was also highlighted after removing PGM* and PGI-1* loci which may be under selection. These results can be explained by the chaotic genetic patchiness hypothesis. In contrast, the mtDNA data indicated genetic homogeneity among localities showing the absence of structure in white seabream populations across the Siculo-Tunisian Strait. Historical demography of this species suggests that it has undergone a recent population expansion as a consequence of a bottleneck event during the Pleistocene glaciations. [ABSTRACT FROM AUTHOR]

Geographic and temporal genetic variation of allele frequencies at 21 isozyme loci were examined in two populations of common Pandora, Pagellus erythrinus (Linnaeus, 1758, Sparidae). Fishes were sampled from Western and Eastern Mediterranean basins off Tunisian coasts over one year at the beginning of each season. Analysis of genetic diversity showed a low level of heterozygosity for all populations (average He=0.052). Fixation indices reflected a significant departure from Hardy_Weinberg equilibrium with heterozygote deficiencies, slight spatial differentiation between both sampling localities (FST=0.003, P=0.017) and temporal genetic stability at seasonal and annual scales. Annual genetic variation was evaluated over a five-year period estimated indirectly from fish otoliths. Comparison of genetic diversity between year classes of both locations showed an increase of the He values concurrent with age, supporting the hypothesis of the high variance in individual reproductive success. Finally, our results suggest that the effective population size of Pagellus erythrinus is large and genetic drift is weak but variable, especially between successive adult year classes for both sampling locations. [ABSTRACT FROM AUTHOR]