The Bay of Málaga is located in a high biodiversity and productivity area that harbours a wide variety of commercial species exploited by different fishing fleets. Benthic and demersal fauna from circalittoral soft bottoms have been studied using a benthic dredge (BD) (8 sampling stations) and an otter trawl (OT) (8 sampling stations on a seasonal basis). Some sediment and water column variables, as well as the trawling activity, have also been studied and used for analysing their linkage with the fauna. A total of 287 species have been found in these bottoms and fish, molluscs and crustaceans represented the most diverse and abundant faunistic groups. A new record of the decapod Hippolyte leptometrae for Spanish waters is also included in this study. Some multivariate analyses using BD samples indicated the presence of three assemblages, but these seem to represent different facies of a single benthic community due to the absence of acute sediment changes and significant differences in the fauna. OT samples only displayed differences related to seasons but not to sediment types or depth. These seasonal differences seem to be linked to biological and ecological features of both dominant and/or commercial species. Mud and organic matter contents (%OM) in sediment, as well as the temperature, were the main variables linked to the spatial distribution of the benthic community identified with BD, whereas medium and coarse sand as well as gravel contents were the main variables linked to the changes of the epibenthic and demersal assemblage resulting from OT samples. The information of this study is of importance for improving the knowledge on the biodiversity of circalittoral soft bottoms of the Mediterranean and Alboran Sea as well as for the potential creation of a Marine Fisheries Reserve in the Bay of Málaga.

Megabenthic soft bottom communities of trawlable grounds have been studied since the first few decades of the last century, thanks to trawl fishing technologies. Despite providing an extensive amount of presence data, trawling cannot be considered reliable from a quantitative point of view, frequently giving only weak information about sessile species density, large and small-scale distribution and main habitat features. The recent development of visual technologies on remotely operated vehicles (ROVs) can give a more accurate approach for the study of mega-epibenthic communities. The present study reports the application of both ROV imaging and trawling approaches for the study of a large aggregation (i.e. field) of the red sea pen Pennatula rubra in the Ionian Sea. Density, biomass and population structure were studied in the same population of P. rubra. The density assessed by ROV was significantly higher than that estimated with a three-year series of trawling surveys. Trawling gear efficiency in the removal of P. rubra was low overall. Incidental mortality can be very high due to damage to those specimens that encounter the trawl net but are not directly captured. However, sampling of several colonies by trawling was necessary to establish biometric correlations to estimates of size and biomass from ROV imaging. Trawling catch abundance/biomass data could be useful to identify areas of higher concentration of sea pens, while ROV imaging can be used to monitor these fields in a non-destructive manner that would be consistent with protection measures.

The composition and structure of sublittoral faunal assemblages inhabiting soft bottoms (15–72 m depth) within the Marine Protected Area ‘Acantilados y Fondos Marinos de Calahonda-Castell de Ferro’ in southern Spain (North Alboran Sea, Mediterranean) have been studied in relation to sediment and water column variables. Three assemblages were identified and corresponded to mixed bottom, unstable bottom and coastal detritic bottom assemblages, based on Pérès & Picard's (1964) benthic classification. A total of 14,318 individuals were collected and 218 species identified, molluscs being the best represented group (141 species). Species richness displayed significant differences with depth and transect, with the highest values observed in the medium to very fine sand and muddy bottoms with bioclasts located at the shallowest sampling stations. The presence of some rare and poorly known invertebrates that are scarce in other areas of the Mediterranean Sea is remarkable, such as the crustacean decapods Bythocaris cosmetops and Pagurus mbizi, Atlantic species with no records in the Mediterranean Sea, and the bathyal molluscs Poromya granulata and Alvania testae, collected at shallow depths. The spatial distribution of faunal assemblages was mainly related to depth and percentage of gravel and clay according to the canonical correspondence analysis. The geographic location of the area, the heterogeneity of soft bottoms and the presence of upwellings in the area may favour the high biodiversity found in the studied soft bottoms. This study increases the scarce knowledge of the circalittoral fauna of sedimentary habitats of the Alboran Sea, providing a baseline for the management of this interesting SCI and for the EU Marine Strategy Framework Directive.

This paper presents an inventory of the species of molluscs collected on the continental shelf and upper slopes (70–500 m depth) on the Pacific side of Colombia. In 2002, 39 trawl samples were taken on soft bottoms by the RV ARC ‘Malpelo’. Thirty-eight species of bivalves were collected, comprising living animals and dead collected shells. Information on abundance, Colombian distribution and depth range is provided. Thirty-four species represent the first records for the Colombian Pacific, significantly increasing the number of shelf and slope species known in the region.

An inventory of the main epibiont organisms on living specimens, on empty shells and on pagurized shells of Fusitriton magellanicus collected in Zygochlamys patagonica fishing grounds off Argentina is provided here. Additionally, considering that the presence of the thick, hairy periostracum could be an inhibitor of boring and encrusting species, we analyse the presence of a periostracum in living F. magellanicus in relation to the presence of epibionts. More than 70% of all shells bore encrusting organisms (of at least 30 taxa) but only a small proportion of shells was heavily fouled, the majority of living, empty and pagurized shells being lightly or moderately fouled. Polychaetes were the most common epibiont group (present on more than 60% of shells) while sponges and ascidians were responsible for the majority of the heavily fouled living gastropods. In general, specimens had a moderate level of encrustation and, simultaneously, a low or medium coating of periostracum. Hairy gastropods (only 14% of the sampled specimens) had few or no epibionts. A relationship between the size of the shell and the level of encrustation was only found in living gastropods. Fusitriton magellanicus is the second species in importance (after the Patagonian scallop) for the provision of a hard settlement substrate in the shelf-break frontal area of the Argentine Sea.

The trophic composition of macrobenthic communities in intertidal and subtidal soft-bottoms of the Ensenada de San Simón (north-western Spain) was found to be related to a number of environmental variables. Distribution and abundance of trophic groups have been studied, to provide essential baseline information for monitoring the area, after its designation as a Natura 2000 Special Conservation Zone. Analyses of trophic data showed a numerical predominance of the herbivores in the inner part of the inlet, while sites at the oceanic-influenced area were numerically dominated by surface-deposit feeders. These dominances were mainly due to Hydrobia ulvae in the intertidal area and to polychaetes at the subtidal one. Both univariate and multivariate statistical analyses showed that the sediment composition (organic matter and silt–clay contents) and temperature of the bottom water influenced the benthic macrofauna and were correlated with their trophic composition, abundance and distribution.

Fish stocks found on lagoon bottoms and near reefs are characterized by a high diversity and heterogeneous habitat which make stock estimation difficult. In particular, it is necessary to combine several methods in order to evaluate the major components of these stocks. The present study aimed at estimating reef fish stocks in the Northern Province of New Caledonia, a region where they represent a major target for the local fishermen. These estimates were based on experimental fishing with handlines and bottom longlines. Handlines were used to assess the stocks near reefs, and longlines for those in areas away from reefs and on lagoon soft bottoms. Handline stations (363) were sampled in three different regions (west, north and east lagoons) and three biotopes (nearshore, middle lagoon and barrier reef). A total of 104 species were caught, the major families being Lethrinidae, Lutjanidae and Serranidae. Species composition and catch per unit of effort (CPUE) varied among regions and biotopes. In particular, the north zone showed characteristics of an unexploited area with very high yields. An increase in CPUE and fish size from the coast towards the barrier reef and with increasing depth was observed in all regions. Correlations between CPUE from handlines and the numerical density and biomass estimates from underwater visual censuses (UVC) performed on nearby reefs were significant. A total of 206 longline stations were sampled in the west and east regions. A total of 80 species were caught, the major families being the same as those caught in stations with handlines with the addition of Carangidae. The CPUE of longlines was significantly correlated with numerical density and biomass estimates made by UVC along the longlines. Stock estimates based on the correlations between CPUE from handlines or longlines and UVC estimates indicate that 90 % of the lagoon stock were found on soft bottoms and near reefs. Reefs, despite biomasses that were five times larger than soft-bottom and near-reef areas, made only a small contribution to total stock. The ratio between density and CPUE was highest for the lowest densities, thus indicating that fishing efficiency increased with density. Comparison of handline catch performed around reefs and UVC data from nearby reefs suggests that there were bold relationships between the fish assemblages of these two biotopes.