• Quetglas A.Valls M., Capezzuto F., Casciaro L., Cuccu D., González M., Ikica Z., Krstulovi? Šifner S., Lauria V., Lefkaditou E., Peristeraki P., Piccinetti C., Vidoris P., Keller S., 2019. Long-term spatiotemporal dynamics of cephalopod assemblages in the Mediterranean Sea. In Mediterranean demersal resources and ecosystems: 25 years of MEDITS trawl surveys. M.T. Spedicato, G. Tserpes, B. Mérigot and E. Massutí (eds). Sci. Mar. 83S1: 000-000.

ABSTRACT: The Mediterranean Sea shows a trend of increasing temperature and decreasing productivity from the western to the eastern basin. In this work we investigate whether this trend is reflected in the cephalopod assemblages found throughout the Mediterranean. Data obtained with bottom trawl surveys carried out during the last 22 years by EU Mediterranean countries were used. In addition to analysing spatial differences in cephalopod assemblages, we also analysed putative temporal changes during the last two decades. For this purpose, the basin was spatially divided into bioregions, the trawling grounds were subdivided into depth strata, and the dataset was split into two time series of 11 years each. All analyses were done using PRIMER software. The species richness did not vary with the longitudinal gradient, though in most bioregions it showed a mild decrease with depth before plummeting in the deepest waters. Cluster analysis revealed four different bathymetric assemblages in all bioregions. Despite the contrasting conditions between basins and the claims of biodiversity loss, our study revealed that spatial and temporal differences during the last two decades were restricted to changes in the relative abundance of species from a common pool of species inhabiting the whole Mediterranean.

Keywords: monitoring, bottom trawling, biodiversity, biogeography, dominant species, continental shelf, continental slope

  • Hidalgo M., Ligas A., Bellido J.M., Bitetto I., Carbonara P., Carlucci R., Guijarro B., Jadaud A., Lembo J., Manfredi C., Esteban A., Garofalo G., Ikica Z., García C., Gil de Sola L., Kavadas S., Maina I., Sion L., Vittori S., Vrgoc N. Size-dependent survival of European hake juveniles in the Mediterranean Sea. In Mediterranean demersal resources and ecosystems: 25 years of MEDITS trawl surveys. M.T. Spedicato, G. Tserpes, B. Mérigot and E. Massutí (eds). Sci. Mar. 83S1: 000-000.

ABSTRACT: Most studies on European hake focus on the recruitment process and nursery areas, whereas the information is comparatively limited on the ecology of the juvenile stage (ca. second year of life)—the one most exploited by the Mediterranean trawl fisheries. Using information of the MEDITS programme, we provide a spatial and temporal assessment of the influence of body size and growth on hake survival from recruits (age 0) to juveniles (age 1), along with the impact of surface temperature and chlorophyll variability. At a biogeographic scale, size-dependent survival is supported, with areas with higher mean length of recruits and juveniles yielding higher survival. A similar pattern was observed at interannual level in some western Mediterranean areas, also mediated by a density-dependent effect on growth. However, the most recurrent inter-annual pattern was a negative effect of size on survival, which could be attributed to potential ontogenetic changes in catchability and underrepresentation of intra-annual recruitment pulses that are seasonally inaccessible to the MEDITS survey. Results also evidence that survival in the Alboran and Adriatic seas is dependent on the primary production variability, and that Corsica and Sardinia could be potential feeding grounds receiving juveniles from neighbouring areas. The present study reveals the importance of size- and growth-dependent survival in the juvenile stage of European hake in the Mediterranean Sea.

Keywords: juvenile survival, european hake, Mediterranean Sea, size dependence.

ABSTRACT: Crustaceans suffer from diseases that can alter their survival and ecology with additional economic consequences for fisheries and aquaculture. Many parasites have been described from crustaceans and with the advent of novel technologies such as next generation sequencing, the discovery of novel parasites has become increasingly efficient. Molecular techniques are beginning to surpass more conventional tools for parasite discovery, but they typically do not provide information on pathology. Histopathology remains one of the least expensive methods for parasite discovery and allows for both detection of parasites and descriptions of the pathology they cause. When used in concert with modern molecular and electron microscopy techniques, the approach is powerful; however, there are few informational tools for the interpretation of histological slides from crustaceans. Those available do not provide comprehensive images of all organs and early works were limited to lower resolution than currently available. More recent texts provide in-depth details of infection in histological section, but few provide images of healthy material or describe a baseline from which to compare. Here, we provide a series of image plates derived from histologically processed tissues from three palinurid lobsters: Panulirus argus, Palinurus elephas and Panulirus guttatus. Histology from these lobsters shows high visual similarity in all tissue types. We provide a histological atlas of healthy tissue that can be used as a baseline resource for pathobiologists working on these common species (and related crustaceans) and we discuss how disease may result in visual aberrations to these tissues.

Keywords: Histology, Panulirus, Pathology, Parasite, Disease .

  • George Tserpes, Enric Massutí, Fabio Fiorentino, Maria Teresa Facchini, Claudio Viva, Angélique Jadaud, Aleksandar Joksimovic, Paola Pesci, Corrado Piccinetti, Letizia Sion, Ioannis Thasitis, Nedo Vrgoc. Distribution and spatio-temporal biomass trends of red mullets across the Mediterranean. In "Mediterranean demersal resources and ecosystems: 25 years of MEDITS trawl surveys. M.T. Spedicato, G. Tserpes, B. Mérigot and E. Massutí (eds). Scientia Marina 83S1
    December 2019, 000-000, Barcelona (Spain). ISSN-L: 0214-8358.

ABSTRACT: The present work examines the spatio-temporal biomass trends of Mullus barbatus and Mullus surmuletus in the Mediterranean Sea through the analysis of a time series of data coming from the Mediterranean International Trawl Surveys (MEDITS), accomplished annually from 1994 to 2015. The biomass of both species showed clear declining trends below 150 to 200 m depth, which were steeper in the case of M. barbatus. Increases in temporal biomass trends were observed for M. barbatus from 2008 onward in most geographic sub-areas (GSAs), while stability was mostly observed for M. surmuletus. For both species, dynamic factor analysis revealed similarities among neighbouring GSAs and the subsequent cluster analysis identified two major GSA groups corresponding to the eastern and western basins of the Mediterranean. Overall, the results suggested that the combined effects of fishing and environmental conditions determine species abundance variations, but the relative importance of each component may vary among areas.

Keywords: red mullet; striped red mullet; distribution; trends; Mediterranean.

ABSTRACT: The holothurian Parastichopus tremulus, a species only know from the north-eastern Atlantic, is reported for the first time from the Mediterranean Sea. Five individuals of the species were collected in the vicinity of the Seco de los Olivos sea mount in May 2017 from a bottom trawl sample carried out during the MEDITS trawl survey. Scanning Electron Microscope images of body wall ossicles are supplied to support species identification. Connectivity between Atlantic and Mediterranean populations of P. tremulus is suggested due to the existence of a nearby Atlantic population in the Gulf of Cádiz and the documented presence of abundant holothuroid larvae in the anticyclonic gyre which originates in the Atlantic current entering the Mediterranean, near the Strait of Gibraltar.

Keywords: echinoderm; stichopodidae; atlantic inflow; taxonomy; morphological examination.