Abstract. The distribution of the macrobenthic community, in relation to various physical and chemical characteristics of the sediment, was studied along the coast of Southern Tuscany (Central Tyrrhenian) in an area under the influence of the Ombrone River outflow. The zonation of the benthos was found to be primarily under the control of a gradient of water movement, as is reflected by variations in the sediment structure from the coast to the open sea. This correlation is somehow influenced by secondary gradients such as the degree of mixing of the sediment and the deposition of terrigenous materials along the river plume.
SUMMARY The systematic position of the Gnathostenetroidea is revised with reference to the other superfamilies of Asellote isopods. An attempt is made to reconstruct the evolution of the sub-order Asellota. The role of the Gnathostenetroidea as a link between Stenetroidea and Janiroidea is emphasized, while the hypothesis that they may have given rise to Stenasellidae or to Asellidae is rejected. The taxonomic position of fresh-water subterranean genera is discussed. These genera, Protojanira Barnard and Protojaniroides n.gen., are placed into new family Protonjaniridae n.fam. The marine genera, Gnathostenetroides Amar, Caecostenetroides Fresi & Schiecke and Maresiella Fresi & Scipione, are grouped into a second family, the Gnathostenetroidae n.fam.
Abstract. The vertical zonation of the hydroid fauna associated with Posidonia oceanica leaves in three different localities of the central Mediterranean reveals the presence of two distinct communities. This depth‐related zonation shows patterns that are independent on the geographic area.
The towed undulating vehicle (TUV), named SARAGO, was used for two fine-scale surveys between the Italian and the Sardinian coasts during the Astraea 2 cruise (6–7 and 26–27 September 1995), studying the deep chlorophyll maximum distribution. SARAGO sections identify a sub-surface doming with higher chlorophyll a and primary production concentrations in the upwelling area of a cyclonic gyre region, detected by sea-surface temperature images. In the first section, the cyclone presents a double doming, in density and salinity, with shallower and concentrated patches of chlorophyll a for about 2 miles. Twenty days later, the second section shows that the gyre changes shape and extension, showing a single doming with higher primary production and chlorophyll a concentrations, distributed over a large area of about 40 nautical miles. SARAGO allows analysis of this high-variability phenomenon (cyclonic gyre) and allows concentrated patches (2 nm) to be identified, thus proving the importance of TUVs in the study of mesoscale processes.
Abstract Two species of Polychaetes new to the Mediterranean fauna are reported: Lumbrinereis inflata (Moore, 1911) and Streblosoma hesslei Day, 1955. L. inflata is morphologically and ecologically compared to the closely allied L. coccinea. Morphological and ecological information is given also on S. hesslei.
