Serenella Cabiddu

Diet and feeding habits of two skate species, Raja brachyura and Raja miraletus (Chondrichthyes, Rajidae) in Sardinian waters (central‐western Mediterranean)

The diet and inter‐ and intraspecific interactions of two shallow‐water skates, Raja brachyura and R. miraletus, caught at depths between 30 and 162 m during trawl surveys carried out in 2005 and 2006 in the seas surrounding Sardinia (central‐western Mediterranean), were analysed. The low values of Levin and Shannon indexes (Bi = 0.37 and 0.42, respectively, for the former, and H′ = 1.31 and 1.62, respectively, for the latter) showed that these two species are specialized predators. An ontogenetic analysis of the diets of three size groups showed that they adopted similar trophic habits. Young R. brachyura specimens (Bi = 0.27; H′ = 1.05) feed mainly on Crustacea (% IRI = 74) (mainly Mysidiacea and Amphipoda Gammaridea), which were replaced in the diet of medium‐large specimens principally by Osteichthyes (mainly Gymnammodytes cicerelus). Multidimensional scaling analysis indicated a high level of intraspecific competition between medium and large individuals. In R. miraletus, Crustacea represented the main prey in all size groups (% IRI = 99.5, 99.6, and 88, respectively). Amphipoda Gammaridea were the predominant prey for small individuals, and were replaced in medium and large specimens by decapods. Low levels of interspecific competition were generally found.

Abnormal rostrum in Polycheles typhlops Heller, 1862 (Decapoda: Polychelidae) from the Central Western Mediterranean

Abstract Anomalies of the number of rostral spines have been recorded in blind lobsters, Polycheles typhlops, caught in Sardinian waters (Central Western Mediterranean). The abnormal specimens, 66 out a total of 789 individuals analysed, showed all the morphometric characteristics of P. typhlops except for the unusual presence of two rostral spines instead of the canonical one. The analysis of partial nucleotide sequences of the mitochondrial cytochrome oxidase subunit I gene (COI) showed that the individuals with two spines were not genetically different from the normal specimens of P. typhlops, while both were quite dissimilar from the other Mediterranean species, P. sculptus. Our results suggest the need of an update of the morphological classification guides for this family combined with a wider genetic study.

Gonad development of the deep-sea lobster Polycheles typhlops (Decapoda: Polichelidae) from the Central Western Mediterranean

Abstract In this paper, we report data related to the reproductive biology of a cosmopolitan mesobathyal lobster, Polycheles typhlops (Decapoda: Polychelidae), caught in the Sardinian waters between 400 and 1400 m of depth. Macroscopic and microscopic analyses were performed on 1104 females and 895 males. The observation on the gonads leads us to conclude that there are seven and four stages of development for the females and for males, respectively. Monthly variations of the percentage distribution related to various stages of development of the ovary and the presence of ovigerous females indicated that the species does not seem to follow a marked seasonal reproductive model, with a long main period for egg hatching that seems to occur between spring and autumn.

Larval Helminth Parasites of Fishes and Shellfishes from Santa Gilla Lagoon (Sardinia, Western Mediterranean), and Their Use as Bioecological Indicators

Qualitative and quantitative data of the larval stages of 30 helminth species infecting fish and shellfish in the Santa Gilla lagoon (southern Sardinia, western Mediterranean Sea) were collected and analysed to determine their usefulness as biological and ecological indicators. Parasitological data were collected from 2001 to 2011 from 12 fish species, from the families Anguillidae, Atherinidae, Cyprinodontidae, Gobiidae, Moronidae, Mugilidae, Soleidae and Sparidae and from bivalve molluscs of the families Cardiidae, Mytilidae and Veneridae. Digenean metacercariae dominated the larval parasitofauna; nevertheless, the most abundant parasite species was a nematode, i.e. the third-stage larvae of the anisakid Contracaecum rudolphii. Based on their life cycle, the species detected were divided into autogenic or allogenic parasites, which have fishes and birds/mammals as their definitive hosts, respectively. Data on the prevalence, intensity and abundance of infections and the parasitic diversity in each host species were combined with previous knowledge on the life history of the parasites detected, to build a model food web based on the different trophic relations, especially predator–prey interactions between hosts marked by the transmission of parasites. The results will contribute to the knowledge of species diversity and to the evaluation of general environmental changes occurring in brackish Mediterranean ecosystems. In combination with other analytic tools in a multidisciplinary approach, this will enable us to better understand the functioning of other Mediterranean brackish waters that are comparable to the Santa Gilla lagoon.

Gonad Development and Reproduction in the Monoecious Species Chlorophthalmus Agassizi (Actinopterygii: Aulopiformes: Chlorophthalmidae) from the Sardinian Waters (Central-Western Mediterranean)

The shortnose greeneye, Chlorophthalmus agassizi Bonaparte, 1840, is a circumglobal species found in temperate and tropical regions. This species is distributed in the Western Atlantic from Canada to northern South America, in the Eastern Atlantic from Spain to Senegal, and in the Mediterranean Sea (Bini 1970, Robins and Ray 1986, Scott and Scott 1988). Young stages are pelagic, living near the surface, while the adults are demersal, near the mud and clay bottoms, at the 50 to 1000 m depth range, mainly between 350 and 450 m (Fischer et al. 1987). C. agassizi lives between 150 m and 700 m in the Italian seas (Relini et al. 1999). Recently, it has been caught between 70 m to 1163 m in the South Sardinian waters (Follesa et al. 2010). The knowledge of the biology of C. agassizi is poor out of the Mediterranean Sea. Mead (1959) observed an adult specimen captured in the Gulf of Mexico indicating that this species is monoecious and the gonad appears in the form of a combined gonad (ovotestis), with neither component mature. In the Mediterranean, although in some areas, such as the Sardinian and Sicilian seas, it is among the most abundant commercial fish (Cau and Mura 1978, Relini et al. 1999, Follesa et al. 2004b) few studies have been carried out. These studies are mainly related to distribution, population structure, life strategies (Anastasopoulou et al. 2006, D’Onghia et al. 2006) and diet in the Ionian Sea, the Aegean Sea, and Sardinian waters (Kabasakal 1999, Cabiddu et al. 2005, Anastasopoulou and Kapiris 2007). In Sardinian seas, some aspects of the reproductive biology of C. agassizi, based only on histological criteria, such as the identification of oocyte and male sex cells were studied by Follesa et al. (2004a). ACTA ICHTHYOLOGICA ET PISCATORIA (2010) 40 (2): 167–177 DOI: 10.3750/AIP2010.40.2.10

First record of the alien polychaete Naineris setosa (Scolecida; Orbiniidae) in Tyrrhenian Sea (Western Mediterranean)

During a survey in Santa Gilla, a Tyrrhenian lagoon located in southern Sardinia, several specimens of the alien polychaete Naineris setosa were found. 1) A brief description of the specimens is presented; they possess the rounded prostomium and the crenulated capillary chaetae typical of the genus, but they are characterized by the absolute lacking of uncini or subuluncini in thoracic neuropodia, which is unique trait within Naineris; 2) some environmental characteristics of the collection site are measured; 3) the description and the distribution of the specimens are also provided.

Sediments distribution of trace metals in a coastal lagoon (Southern Sardinia, Mediterranean Sea): assessment of contamination and ecological risk

ABSTRACT Coastal lagoons are subject to several sources of contaminations. To shade light on the contamination level of the Santa Gilla lagoon (Tyrrhenian Sea) we investigated the spatial distribution of Cr, Ni, Pb, Zn and Hg in sediments and their correlation with grain size and organic matter contents. Moreover, sediment contamination levels and the ecological risk associated with metal concentration were assessed using different abiotic indicators. The lagoon is characterised by low levels of contamination, with exceptions for Pb and Hg, whose distribution reflects the position of an old chlor-alkali plant and that of an airport. These results indicate that the restoration put in place 30 years ago have not reached the expected target and that the presence of the airport deserves further attention. In the outer section of the lagoon, where clam fishery occurs, we observed low levels of contamination suggesting that such artisanal fishery could somehow help mobilising metals. We conclude that the area exposed to Hg pollution, though tentatively restored, still suffers of a potential risk of ecosystem deterioration. We pinpoint that further investigations on the mobility, bioavailability and toxicity of metals are needed to finally address the actual impairment of the Santa Gilla lagoon.

The Effect of Season on the Metabolic Profile of the European Clam Ruditapes decussatus as Studied by 1H-NMR Spectroscopy

In this study, the metabolome of Ruditapes decussatus, an economically and ecologically important marine bivalve species widely distributed in the Mediterranean region, was characterized by using proton Nuclear Magnetic Resonance (1H-NMR) spectroscopy. Significant seasonal variations in the content of carbohydrates and free amino acids were observed. The relative amounts of alanine and glycine were found to exhibit the same seasonal pattern as the temperature and salinity at the harvesting site. Several putative sex-specific biomarkers were also discovered. Substantial differences were found for alanine and glycine, whose relative amounts were higher in males, while acetoacetate, choline and phosphocholine were more abundant in female clams. These findings reveal novel insights into the baseline metabolism of the European clam and represent a step forward towards a comprehensive metabolic characterization of the species. Besides providing a holistic view on the prominent nutritional components, the characterization of the metabolome of this bivalve represents an important prerequisite for elucidating the underlying metabolic pathways behind the environment-organism interactions.

Morphological variation among geographic populations of the rare finless eels Apterichtus anguiformis and Apterichtus caecus (Anguilliformes: Ophichthidae)

Abstract Morphological analysis of recently collected specimens of the slender finless eel Apterichtus anguiformis (26 specimens) and the European finless eel Apterichtus caecus (14 specimens) in waters off the coast of Sardinia (central-western Mediterranean) confirmed their distinction from each other. Analysis also revealed a pronounced difference in mouth length in A. anguiformis from Sardinian waters when compared to the holotype and published data. To clarify their taxonomic status, morphological characteristics of the finless eels were analysed using morphometric and meristic characters. The morphometric differences between species were mainly related to the position of the anus and to cranial-related characters. Variation in meristic traits revealed differences in the number of operculum and pre-anal pores as well as the number of total vertebrae. Finally, we were able to capture specimens of these rare species using experimental trawl fishing gear, in which the entire cod-end was covered with a fine mesh net size of 8 mm; this sampling approach would be a good sampling method for further studies.

Ovary development in the deep-sea shrimp Acanthephyra eximia Smith, 1884 in Sardinian waters

We report data regarding the gonad development in females of Acanthephyra eximia Smith, 1884. Specimens were caught during experimental surveys carried out in Sardinian waters between 500 and 1880 m. We employed for our analysis of the ovary development both macroscopic observation and histologic analysis. According to the macroscopic observations, carried out on 491 specimens, six developmental stages of the ovaries were identified. These were validated by histologic analysis, performed on a sample of 10 specimens per stage, that allow us to describe different cell types. A table whith both macroscopic and histologic stages of the female gonad of A. eximia are briefly summarized.