Maria Flavia Gravina

Depth-size distribution pattern of Parapenaeus longirostris (Lucas, 1846) (Decapoda) in the central Mediterranean Sea

ABSTRACT The bathymetric distribution pattern of the rose shrimp Parapenaeus longirostris (Lucas, 1846) was analyzed in order to understand the life cycle and migratory behavior, and to construct the growth curve. Five research cruises were carried out in the central Mediterranean Sea (Latium, Italy). Parapenaeus longirostris was captured between 100-m and 508-m isobaths and the highest abundances were observed mainly between 150-m and 350-m isobaths. Recruitment of new generations to the epibenthos essentially occurred between 100-m and 180-m isobaths during the summer. A multivariate ordination method (factorial analysis of correspondence) was used to describe the relationship between the length of the shrimp and the depth. The benthic fraction of the population appeared to be linked to a migratory movement from the middle shelf towards the continental slope. By estimating the parameters of the Von Bertalanffy equation, it was found that the growth of males appeared slower than that of females. The life span of each generation time was about two years.

Polychaetes of an artificial reef in the central mediterranean sea

The development of a polychaete community over five years on a man-made reef was analyzed. The reef was composed of 280 concrete blocks (2 × 2 × 2 m) and located in the Tyrrhenian Sea (Italy) 1.5 miles offshore and 12–14 m deep. Sixty-three species were collected—serpulids, nereids and cirratulids being the most abundant families. Ordination by Principal Components Analysis (PCA) technique showed three main stages in the colonization process: a pioneer phase, when mainly serpulids (Pomatoceros triqueter, P. lamarckii, Hydroides pseuduncinata) occurred; a second phase, characterized by mussel (Mytilus galloprovincialis) dominance and a more differentiated community structure with a lot of new species especially recurring on hard bottom (Serpula concharum, H. dianthus, Ceratonereis costae); and a third phase, with an alteration of the substratum through soft deposits and the polychaete community characterized by also the occurrence of soft bottom species (Heteromastus filiformis, Polydora ciliata, Dorvillea rubrovittata). From the trophic point of view, the structure of the community changed from dominance by filter feeders (97%) to a more differentiated situation with abundant detritic feeders (c. 20%). The rates of immigration and extinction and the colonization curve showed that an actual stable steady-state was not reached.

Biodiversity of transitional waters: species composition and comparative analysis of hard bottom communities from the south-eastern Italian coast

Numerous studies have focused on the soft bottom macrozoobenthos from Mediterranean transitional environments, pointing out a correlation between the variation in environmental parameters and changes occurring in benthic communities. Less attention has been paid to the study of hard bottom organisms settling on both natural and artificial substrates usually present within the basins and often constituting peculiar communities. The ecological role of such communities is remarkable, since they often reach high values of species richness and include bioconstructor organisms able to build true reefs. These reefs can strongly impact the environment, improving biodiversity through the increase of spatial heterogeneity. The present work aims to supplement new faunistic data on five lagoon systems of the south-eastern Italian coast, integrating the still fragmentary knowledge of their macrozoobenthos through the study of hard substrate communities. Sampling was performed on hard substrates colonized by complex benthic communities. The assemblages recorded were then compared in the light of the study sites’ main ecological traits. Our data highlighted the occurrence of a rich benthic macrofauna, with 100 taxa found. This markedly increases the value of species richness reported in the literature for the macrozoobenthos of the study sites. In particular, the species list provided for the Ugento Basins was the first ever compiled for this site. In spite of their geographical proximity, the investigated sites, according to their diverse environmental conditions, showed substantial differences as regards their respective macrozoobenthic communities.

Mediterranean Bioconstructions Along the Italian Coast

Marine bioconstructions are biodiversity-rich, three-dimensional biogenic structures, regulating key ecological functions of benthic ecosystems worldwide. Tropical coral reefs are outstanding for their beauty, diversity and complexity, but analogous types of bioconstructions are also present in temperate seas. The main bioconstructions in the Mediterranean Sea are represented by coralligenous formations, vermetid reefs, deep-sea cold-water corals, Lithophyllum byssoides trottoirs, coral banks formed by the shallow-water corals Cladocora caespitosa or Astroides calycularis, and sabellariid or serpulid worm reefs. Bioconstructions change the morphological and chemicophysical features of primary substrates and create new habitats for a large variety of organisms, playing pivotal roles in ecosystem functioning. In spite of their importance, Mediterranean bioconstructions have not received the same attention that tropical coral reefs have, and the knowledge of their biology, ecology and distribution is still fragmentary. All existing data about the spatial distribution of Italian bioconstructions have been collected, together with information about their growth patterns, dynamics and connectivity. The degradation of these habitats as a consequence of anthropogenic pressures (pollution, organic enrichment, fishery, coastal development, direct physical disturbance), climate change and the spread of invasive species was also investigated. The study of bioconstructions requires a holistic approach leading to a better understanding of their ecology and the application of more insightful management and conservation measures at basin scale, within ecologically coherent units based on connectivity: the cells of ecosystem functioning.