The composition, taxonomic structure and distribution patterns of bathyal benthic fauna of the northern Mid-Atlantic Ridge between the Azores and the southern tip of the Reykjanes Ridge were studied from specimens collected on the ‘G.O. Sars MAR–ECO’ expedition in July 2004. Material was obtained from 16 Campelen 1800 trawls taken north of the Azores (42°N) and in two areas around the Charlie-Gibbs Fracture Zone (CGFZ) (51°N and 53°N) at depths 1237–3527 m. A total of 192 species were recorded. Overall the MAR–ECO benthic fauna was dominated by echinoderms (49.5% of the total species sampled), sponges (18.2%) and anthozoans (16.7%). Between-station species similarity was analysed using non-metric multidimensional scaling. Our analysis revealed differences between stations from the CGFZ and the Azorean regions. Stations from the Azores formed one cluster whereas stations from the CGFZ separated into two groups related to depth: stations from depths 1263 m to 1916 m and those from 2350 m to 3512 m. The taxonomic structure of the bathyal fauna was also different in the Azores than in the CGFZ areas. At the CGFZ, taxa with the highest percentage of species present were different above and below the 2000 m bathymetric contour, in contrast close to the Azores taxa with the highest percentage of species were the same shallower and deeper than 2000 m. Our results point at turnover in benthic bathyal fauna between the Charlie-Gibbs Fracture Zone and the Azores, which could be related to the presence of the Sub-Polar Front.

Karyotypes for several East Pacific Rise hydrothermal vent invertebrates are described here for the first time: the vestimentiferans Riftia pachyptila and Oasisia alvinae, the alvinellid polychaetes Alvinella pompejana, A. caudata and Paralvinella grasslei, the polynoid polychaetes Branchinotogluma grasslei and Branchipolynoe symmytilida, the serpulid Laminatubus alvini and the mytilid bivalve Bathymodiolus thermophilus. For comparative purposes, the karyotype of the Atlantic vent mussel Bathymodiolus azoricus is also described here for the first time. Each species has its own unique chromosomal characteristics which can be interpreted both in terms of group characteristics and species divergence. From comparisons with published results on other vent species and closely-related coastal species, we identified a positive correlation between chromosome number variation and molecular divergence at two ribosomal ribonucleic acid gene loci (the 18S and 28S rRNA). Whilst the patterns of chromosome divergence we found were generally within the ranges previously reported for these taxonomic groupings, there was an apparent inconsistency in the case of Branchipolynoe symmytilida (EPR) and Branchipolynoe seepensis (MAR), which show a greater degree of divergence at the chromosome level compared with other members of the same genus. Moreover, polychaetes as a whole showed greater variation in the number and structural divergence of chromosomes compared to Mytilids (structural information only). Our findings highlight the great potential for chromosome analysis in future taxonomic and evolutionary studies of the deep-sea vent fauna.

International efforts are currently being made to establish networks of marine protected areas (MPAs) for the purposes of conservation of marine biodiversity. One of the primary objectives of MPA networks is to achieve representation of all marine biological diversity. Since we do not know the extent of biological diversity nor its distribution and function, we use surrogates to represent biological diversity. At a broad scale, measures of the physical environment are used, however at a fine scale biological assemblages have been shown to provide better representation of known biological diversity. While there are well known descriptions of assemblages for shallow water environments, few such descriptions of deep-sea benthic assemblages have been attempted. This paper provides descriptions of deep-sea epibenthic megafaunal assemblages based on a broad-scale video and stills image survey of the upper bathyal (200–1000 m) regions of the Rockall Trough and eastern Faroe–Shetland Channel. One thousand nine hundred and eighty-seven images were analysed from 139 video transects sampled from Dangaard and Explorer Canyons, Rosemary Bank Seamount, Hatton Bank, Wyville-Thomson Ridge, and the continental slope west and north-west of Shetland. Quantitative data obtained were analysed using cluster analysis and SIMPER analysis in Primer V.6 to identify benthic assemblages and their characterizing species. Thirty-one epibenthic megafaunal assemblages are defined by their characterizing species, and their distribution in terms of site, depth, temperature and substratum type. These 31 ‘biotopes’ provide consistent units for use in biological mapping efforts and assessments of representativeness in MPA network design. To facilitate the incorporation of these biotopes into existing deep-sea classification systems the biotopes have been assigned to broad substratum types. This is consistent with the use of substratum as a surrogate in many existing systems.

An ex-Royal Navy frigate, HMS ‘Scylla’, was placed on the seabed in Whitsand Bay, south Cornwall on 27 March 2004. After five years, the reef supported a mature steel wreck community. The colonization of the reef showed wide fluctuations in species abundance in the first two years but, by 2006, most species that dominated or characterized the reef after five years had settled. Significant colonization events included settlement of barnacles, tubeworms and hydroids within a month and remarkably high settlements of the sea urchin Psammechinus miliaris and the queen scallop Aequipecten opercularis in the first year together with starfish Asterias rubens, solitary sea squirts and ephemeral algae. The plumose anemone Metridium senile, a characteristic species of wrecks, arrived in late summer 2004 but the widely distributed dead man's fingers Alcyonium digitatum was not observed until spring 2005. Wrasse were slow to colonize the reef but were established in small numbers by the end of 2007. Sea fans, Eunicella verrucosa, were first observed in August 2007. The species count for the reef stood at 263 taxa by the end of March 2009. The inside of the reef remained poorly colonized even after five years. Areas coated with tributyltin (TBT) antifouling paint only had colonization where the paint had flaked-off or on non-toxic paint markings, but with some indication that colonization may be occurring by a very few species especially near to non-TBT areas. Many species characteristic of natural reefs had not settled and neither do they occur on older wrecks including branching axinellid sponges, some cushion sponges and the yellow cluster anemone Parazoanthus axinellae. The artificial reef developed a community that was distinctly different to nearby natural rock reefs and such artificial structures should not be considered as a replacement for damaged or destroyed natural habitats.

Size-based analyses of marine animals are increasingly used to improve understanding of community structure and function. However, the resources required to record individual body weights for benthic animals, where the number of individuals can reach several thousand in a square metre, are often prohibitive. Here we present morphometric (length–weight) relationships for 216 benthic species from the North Sea to permit weight estimation from length measurements. These relationships were calculated using data collected over two years from 283 stations. For ten abundant and widely dispersed species we tested for significant spatial and temporal differences in morphometric relationships. Some were found, but the magnitude of differences was small in relation to the size-ranges of animals that are usually present and we recommend that the regression relationships given here, based on pooled data, are appropriate for most types of population and community analyses. Our hope is that the availability of these morphometric relationships will encourage the more frequent application of size-based analyses to benthic survey data, and so enhance understanding of the ecology of the benthic/demersal component of marine ecosystems and food webs.

This paper develops models of the initial impact of marine aggregate extraction on a benthic assemblage. We predict the effect of dredging on species numbers and abundance assuming spatial randomness of individuals. We extend the model to allow for spatial clustering of individuals using a Matern process. Data from a controlled field experiment are used to develop a framework for estimating species reduction. This involves modelling the spatial pattern of individuals before dredging using a Matern process, the impact of dredging at an individual level, and the probability that a species is not seen in a post-dredging survey. The framework was used to estimate that, of the 41 species that were seen in a pre-dredging survey but not in a post-dredging survey, between 0 and 14 were eliminated (with 95% likelihood) rather than escaped detection. The most likely number eliminated was 4.

Sandy bottoms, with local patches of rocks, dominate the southern Baltic Sea coast. These rock patches create three-dimensional habitats with additional niches that can support diverse assemblages of organisms. In this study we investigated macrofaunal assemblages associated with the boulder field in the brackish Gulf of Gdansk. Of the 30 recorded taxa three animal species (Mytilus trossulus, Balanus improvisus and Electra crustulenta) together with five species of algae were directly attached to rocks. These engineering organisms provided habitats for a further 22 taxa. Among the fauna directly associated with rocks, barnacles (76%) were the most abundant while among indirectly associated biota, oligochaetes were the dominant group (45%). Rock size and algal biomass explained most variance in macrofaunal structure of the assemblages investigated. There were statistical differences in assemblage structure between two separate localities within the rocky patch, despite environmental homogeneity (salinity, water temperature and structure of sea bottom). These differences in assemblage structure were mostly due to differences in dominance of particular species rather than in species composition. Our results show that rocky patches in an otherwise soft sediment habitat provide additional living space for macrofauna leading to an increase in local biodiversity and organismal abundance.

During two sampling campaigns carried out in August 1998 and November 2002, 232 cumaeans from eight species belonging to the families Bodotriidae and Nannastacidae were collected. This paper presents the first ecological data on a shallow water tropical cumacean assemblage from the Persian Gulf, where 50% of the existing species were recently described as new for the science. Neither the environmental conditions (except for the sediment organic content) nor the cumacean assemblage descriptors differed between the two sampling periods. However, two different species dominated in each period (i.e. Eocuma travancoricum and Heterocuma inerme in 1998 and 2002, respectively) and the MDS analysis revealed differences in the assemblage composition between periods, particularly for the deepest sampling stations. An increasing density together with the increase in gravel content, and a decreasing density together with the increasing silt content characterized the distribution pattern of both the whole cumacean assemblages and the two dominant species, the latter being also positively correlated with the mean grain size and negatively correlated with depth and organic matter (E. travancoricum) and with depth (H. inerme).

The present study was undertaken in order to analyse whether macrobenthic communities can or not be used in monitoring programmes of the environmental quality of fish ponds. Functional community analysis and biotic metrics were analysed aiming at the assessment of their effectiveness in discriminating potential impacts of fish production in these systems. The macrofaunal patterns in earthen fish ponds of the Ria Formosa lagoon showed to be influenced by the input of fish food during the production cycle and by changes in abiotic parameters caused by seasonality and fish production. Polychaetes were generally dominant considering the number of taxa and abundance. The trophic functional analysis of the benthic communities showed that the deposit-feeding functional group dominated in both areas of the ponds but within water entrance areas there was an increase of suspension-feeding, carnivory and herbivory feeding modes. The presence of less trophically mixed communities within feeding areas may be related to the relative high disturbance levels of these areas. From the biotic indicators that show a differential response to organic input in fish earthen ponds, the abundance of Capitella spp. as well as the diversity (Shannon–Wiener and Margalef species richness), evenness (Pielou) and AMBI indices seem to be the best indicators to be used in monitoring studies in similar systems. Managers should pay particular attention when Capitella spp. taxa are observed within the feeding areas. Nevertheless, manipulative experiments are needed in order to test the dominance levels of Capitella spp. and the values of those indices that are of concern.

We studied the summer spatial distribution of the copepod community in both the neritic and oceanic areas of the Gulf of Gabès (Tunisia, eastern Mediterranean Sea) coupled with environmental factors. Copepods were the most abundant zooplankton throughout the sampling period, contributing 78% of the total zooplankton. A total of 14 copepod families were identified in all stations, with an overwhelming abundance of Acartiidae and Oithonidae (39.05 and 39.09% of total abundance, respectively). Abundance of Acartia clausi and chlorophyll-a concentrations were negatively correlated with salinity, suggesting that this species probably escaped the high coastal salinity (38 psu). Significant correlation determined between A. clausi and tintinnids at 50 m isobaths indicates that these planktonic ciliates probably served as a substantial food link towards higher trophic levels of this area. Conversely, Oithona nana which was well adapted to high chlorophyll-a concentrations and high salinity along the coast, showed significant correlations with Dictyochophyceae, Dinophyceae, Bacillariophyceae and Euglenophyceae, suggesting that this small copepod was capable of feeding on a wide selection of phytoplankton preys.

In order to investigate the intensity and variability of fouling recruitment on artificial hard substrates, three sites were chosen in the First Inlet of the Mar Piccolo of Taranto (Southern Italy, Ionian Sea). Taxa richness and percentage coverage were examined in three different sampling times within each site. Differences were tested both by univariate and multivariate statistical analysis (ANOVA, SIMPER and MDS). The results show that each site seems to be characterized by its own structural make-up over the whole period of observation, underlying the presence of large-scale variability. By contrast, variability on a smaller scale within each site (replicates) appeared less marked, both in space and time. A set of a quite stable group of species characterized each site. Differences between sites were maintained over time with a difference in community evolution although with a tendency towards a higher similarity in species composition along the time.

Greater understanding of patterns of distributions of organisms and their causal mechanisms are required if the consequences of climatic change are to be fully realized. Associations between topographic features of the environment and distributions of organisms are frequently assumed to be a consequence of provision or modification of local conditions by those features. Such assumptions are rarely supported empirically and there is increasing evidence that topographic features do not always influence variables in the way we might anticipate. Thus, data about how features of habitat influence environmental conditions, including availability of food, are likely to be useful for understanding how and why organisms are found where they are. Such data are few and rigorous descriptions about what defines particular features of habitat are seldom provided or are simplistic. For hard substrata in aquatic environments, crevices are often prominent features with which many species associate. Crevices have frequently been assumed, but not demonstrated, to ameliorate conditions by increasing humidity, moderating (usually reducing) temperatures and by decreasing forces from wave-impacts and water-flow. This study provided clear definitions and tests of various hypotheses about how crevices altered the local environment. The main predictions were that crevices would be cooler, more humid, more sheltered from water-movement and support more micro-algae than areas away from crevices. Manipulative experiments using artificial habitats and measurements on natural rocky shores were carried out on multiple shores over two years to understand how crevices affected local conditions. Crevices were indeed cooler, more humid, supported more micro-algae and more sheltered from water-flow than open areas nearby, but conditions did not always vary in ways that were expected. Effects were often complex, with factors such as season, height on the shore and tidal conditions interacting to influence how crevices affect environmental conditions. Without this detailed information, assumptions about the reasons animals associate with features of habitat cannot be tested.

This study constitutes a preliminary assessment of the abundance and species richness of sponges living on the brown seaweed Sargassum spp. from the southern Gulf of California (Mexico). The diversity and abundance of sponges associated with Sargassum was investigated from November 2006 to November 2007. In addition, it was examined whether temporal variations in the abundance of associations were influenced by changes in size and density of Sargassum as well as environmental factors such as water temperature and salinity. Twelve sponge species (4 Haplosclerida, 3 Poecilosclerida, 4 Dictyoceratida and 1 Clathrinida) were found growing epiphytically on the lower portions of Sargassum plants and the most frequent species were Callyspongia californica and Haliclona turquoisia (38% and 27%, respectively). The abundance of associations showed significant temporal and spatial variations, being higher from June to November (post Sargassum growth period), at depths from 0.5–2.5 m. The number of sponge species m−2 (both epiphytic and non-epiphytic) inside the seaweed bed was 4.8 species m−2, while outside it, the absence of hard substrate for attachment severely restricted the number of sponges. These results suggest that Sargassum provide substratum and habitat for the sponge community from this region, and that their seasonal growth patterns may influence the abundance and diversity of the associations.

Sponges are rare in extreme environments, and very little is known about their adaptations to such settings. Evidence from two species in a marine-derived midwater stratified crater lake on Satonda Island (Sumbawa, Indonesia) suggests their production of gemmules (resting bodies), a rare trait in marine sponges but common in freshwater forms, may be a survival mechanism in the lake's harsh environment. With its epilimnion hydrochemistry—characterized by changing alkalinity, salinity, and O2 levels over the region's wet and dry seasons—the lake sustains only a few marine macroscopic organisms, among them the suberitid sponges Protosuberites lacustris comb. nov. and Suberites sp. (Hadromerida: Suberitida). Both species belong to the same group as sponges reported from other marine-derived lakes with strongly varying and extreme environmental (especially chemical) parameters. The morphological characters, taxonomic position, ecological adaptations, environmental conditions, and biota associated with the sponges in this ecologically unique site are presented here.