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

Differential feeding rates of native and alien predators on the invasive Asian date mussel Arcuatula senhousia (Benson in cantor, 1842) in a Mediterranean coastal lagoon

The alien Asian date mussel Arcuatula senhousia inhabits several coastal environments worldwide. This species can form dense mats where individuals attach through byssus threads, thus altering the structure, functioning and biodiversity of the native communities. We investigated the feeding preference of different predators on this alien species in a Mediterranean coastal lagoon. To do this, a mesocosm experiment was conducted using two crab species (the Mediterranean green crab Carcinus aestuarii) and the Say mud crab Dyspanopeus sayi, and one gastropod, the banded dye-murex Hexaplex trunculus as predators of A. senhousia with or without byssus mats. Our data suggest that C. aestuarii is a more effective predator against A. senhousia than D. sayi, and that H. trunculus is almost ineffective. A possible implication of this result is the potential use of the native crab C. aestuarii for limit the formation of the byssus mats, thus mitigating their potential negative effects on the native communities

Biology, ecology and management perspectives of overexploited deposit-feeders sea cucumbers, with focus on Holothuria tubulosa (Gmelin, 1788)

The increasing harvesting of low trophic level organisms is raising concern about the possible consequences on the ecosystem functioning. In particular, the continuous demand of sea cucumbers from the international market led to the overexploitation of either traditionally harvested or new target species, including the Mediterranean ones. Sea cucumbers are mostly deposit feeders able to consume sedimentary organic matter and, thus, are ideal candidate for the remediation of eutrophicated sediments, like those beneath aquaculture projects. Breeding and restocking of overexploited sea cucumbers populations are well-established prac-tices for Indo-Pacific species like Holothuria scabra and Apostichopus japonicus. Some attempts have also been made for the Mediterranean species Holothuria tubulosa, but, so far, the adaptation of protocols used for other species has presented several is-sues. We here summarize narratively the available information about sea cucumbers rearing protocols with the aim of identifying their major flaws and gaps of knowledge and fostering research about new triggers for spawning and feasible protocols to reduce the high mortality of post-settlers

Organic matter ingestion and assimilation rates by the sea cucumber Holothuria (Holothuria) tubulosa (Gmelin, 1788) at different temperatures and potential effects on benthic trophic status

We investigated the effects of different temperature anomalies (up to +12 °C) on the biochemical features of sediments offered to specimens of the sea cucumber Holothuria (Holothuria) tubulosa (Gmelin, 1788) and of its feces. We also estimated ingestion and assimilation rates of different classes of organic compounds after the different treatments. The exposure to temperature anomalies influenced the metabolism and organic matter assimilation efficiency of H. tubulosa. Counterintuitively, our results would suggest that H. tubulosa, irrespectively of temperature, might not be the best option for removing excess organic matter from eutrophicated sediments, though having consequences on the organic matter nutritional quality. Since oceans’ temperature is projected to further increase by 2100 along with frequency, intensity and duration of marine heatwaves, H. tubulosa will most likely experience a potential contraction of its distribution areal, with cascading consequences on benthic trophic webs dynamics

Chemosensitivity in the Sea Urchin Paracentrotus lividus (Echinodermata: Echinoidea) to Food-Related Compounds: An Innovative Behavioral Bioassay

Like other animals, echinoderms rely on chemical senses to detect and localize food resources. Here, we evaluate the chemical sensitivity of the sea urchin Paracentrotus lividus to a number of stimuli possibly related to food, such as a few sugars, compared to the blue-green algae Spirulina (Arthrospira platensis). To do this we developed a simple, innovative method based on the recording of “urchinograms” estimating the movements of spines, pedicellariae, tube feet, and eventually of the whole sea urchin, in response to chemicals, while keeping both the whole animal and the stimulus in their natural environment, underwater. Our results show that Spirulina is a highly stimulating compound for the sea urchin, by acting in a dose-dependent manner. The animals resulted also sensitive, even if to a lesser extent, to some sugars, such as the monosaccharide glucose, but not to its isomer fructose, while among disaccharides, they sensed cellobiose, but not sucrose or trehalose. From an applied point of view, any insight into the chemical sensitivity of sea urchins toward potential food-related compounds may lead to the discovery of key chemicals that would help improve the efficiency and reduce the costs of dietary substrates for optimization of intensive rearing strategies. Although this method has been developed for P. lividus, it will be suitable to evaluate the chemical sensitivity of other echinoderms and other marine invertebrates characterized by low mobility

Effects of different culture media on growth, composition, quality and palatability of the green algae Ulva sp. cultivated in cylindrical photobioreactors

Ulva spp. are valuable seaweeds with recognized commercial applications, including food, feed, and ecosystem services. Ensuring a sustainable and consistent supply of biomass with desirable profiles aligned with intended uses is fundamental for the successful applications of this seaweed. In this study, the growth rate, morphology, physiology, and composition of Ulva sp. produced by propagation in indoor cylindrical photobioreactors using four different culture media (lagoon water - LW, lagoon water enriched with Guillard medium (LF), with sea urchin wastewater - LU, and cow digestate - LD) was assessed; moreover, the nutrient uptake potential of the species was evaluated. The palatability and attractivity of the produced biomass towards the sea urchin Paracentrotus lividus were investigated. It was found that the media influenced all the parameters examined, the LF biomass weight was double compared to the other treatments and showed a slightly higher absorbance. Colorimetric analyses reported a significant darker color in Ulva sp. grown under enriched media. Ulva sp. showed higher nutrient removal potential in LF. The lipid content did not vary (2–3 % dry weight, DW), while the protein content ranged from 21 % in LF to 6–9 % in the other treatments. Carbohydrates and fiber content were significantly lower in LF (16 % and 30 %) compared to the other treatments, 27–34 %, and 41–48 %, respectively. Pigment content significantly varied, being higher in biomass grown in LF and LU. Sea urchins showed preferences for biomass grown under LU, followed by LD. This study shows how different nutrient sources affect the biochemical composition, growth, quality, and palatability of Ulva sp. When cultivated under the synthetic enriched media (LF) the species exhibits characteristics better suitable for human consumption, although requiring a higher economic investment for production, while biomass derived from wastewater nutrients (LD, LU) confirms potential applications of the seaweed as valuable feed and for bioremediation services

New insights upon the reproductive biology of the sea cucumber Holothuria tubulosa (Echinodermata, Holothuroidea) in the Mediterranean: Implications for management and domestication

Holothuria tubulosa is one of the most common sea cucumber species inhabiting the Mediterranean Sea. Due to its commercial interest for the international market, it has been harvested without proper management causing the overexploitation of its stocks. Inadequate management is also caused by lack of information on basic biology and ecology not allowing the estimating of the species vulnerability and resilience to growing anthropogenic pressures. In this paper, we have investigated basic life-history traits of H. tubulosa (population structure and reproductive cycle) in a population of Central-Western Mediterranean (Sardinia, Italy). A macroscopic maturity scale for both sexes was defined through an instrumental colorimetric analysis of the gonads and the ramification level of the gonad’s tubules, subsequently confirmed by histological analysis. The seasonal trend of the Gonado Somatic Index, the changes in color of the gonads and tubules ramification indicated that the spawning period of H. tubulosa was concentrated in summer with a peak in late August, closely related to the increase in water temperature. A synchronous development of the gonads, with a unique and short reproductive event during the year, was also detected. In conclusion, this study provides new evidence on the biological and ecological features of H. tubulosa, essential data for developing a scientifically-based stock assessment as well as conservative management at a local scale. Finally, we provided basic information for the domestication of broodstock in a conservative hatchery

Distribution of spawning and nursery grounds for deep–water red shrimps in the central western Mediterranean Sea

The presence of spawning and nursery grounds of Aristeids in the central western Mediterranean Sea were investigated using fishery-independent data (trawl surveys, 1994–2012). Spatial distributions were generated for mature animals and recruits, for both spring/summer and autumn data, using an inverse distance-weighted deterministic interpolation. The persistence index was used to identify stable spawning and nursery grounds in the Sardinian slope region for Aristaeomorpha foliacea and Aristeus antennatus. Areas of aggregation for recruits and mature females appear to be connected with important physical habitat features. The analysis also suggests a seasonal bathymetric distribution for nursery areas. The recruits of A. foliacea are located in the upper part of the continental slope (377-450 m) in spring/summer and reach greater depths (468-628 m) in autumn. For A. antennatus, for which nursery areas only emerge in autumn, there is presumably an opposite ontogenic migration, from deep sea to upper slope, during the summer (575-681 m). The results also indicate a partial overlap between the nursery and spawning grounds of both species. In this particular area, local environmental conditions such as upwelling events or the presence of canyons and seamounts seem to play an important role in their distribution. This study also generated relevant information on the spatial and temporal distribution of seasonal or persistent aggregations of spawners and recruits, providing scientific elements to suggest the protection of these important resources

A non‑lethal method to assess element content in the endangered Pinna nobilis

The fan shell Pinna nobilis is the largest bivalve endemic to the Mediterranean and is actually a strongly endangered species. Due to the biological, ecological, and historical relevance of this species, the research of a non-lethal method to relate the element content in organism’s tissues and environment can provide information potentially useful to evaluate environmental pollution and organism physiological status. In this study, a screening on element concentration in the animal growing environment (seawater and sediments) and in four soft tissues (hepatopancreas, gills, mantle, and muscle), and two acellular tissues (calcite shell layer, and byssus) was performed. The comparison among these results was used to assess whether the no-lethal acellular tissue element concentration can be used to reveal the element presence in the environment and soft tissues. Elements, such as B, Ag, As, Mn, Mo, Pb, or Se, showed a possible relationship between their presence in the byssus and soft tissues. In the byssus Cr, Sb, Sn, and V have shown to be mostly related to the environment, more than the soft tissues, and might be used to draw a historical record of the exposure of the organism. The element concentration in the calcite shell layer did not relate with environmental element concentrations. Essential elements, like Cu, Fe, Ni, and Zn, were present in calcite shell layer and byssus and are likely related to their biological activity in the organism. The research also gave an overview on the presence of pollution and on the preferential intake route of the element. In summary, this study, performed on a limited number of specimens of this protected species, indicated that element concentration in the byssus can be applied as non-lethal method to monitor this endangered species and its interaction with the elements in the growing environment