In this study, we analyse spatial patterns of macrobenthic communities of the Río de la Plata system, and assess the species turnover or beta diversity and its relationship with environmental gradients. Macrobenthic samples and physico-chemical parameters were collected from 20 sampling sites along a transect of 560 km, including the freshwater (FW), estuarine (ES) and marine (MA) sectors. Three main assemblages corresponding to the above mentioned sectors were defined with multivariate analysis (cluster, MDS). In total 134 taxa were recorded, 81 in MA, 33 in FW and 38 in ES, represented mainly by polychaete, mollusc and crustacean species. Depth, salinity and %clay showed the strongest correlation with the observed faunal patterns (ρw=0.62; BIO-ENV analysis). Beta diversity varied between dominant taxonomic groups and was positively correlated with changes in salinity. The high variability in the composition of assemblages was reflected in beta diversity, reaching its highest values at the boundaries between the defined sectors. This study suggests that beta diversity represents a useful tool to define ecological boundaries for benthic communities in the Río de la Plata.

Ecological studies of diversity at different spatial scales are important for our understanding of community processes. Here the patterns in the invertebrate fauna associated with the turf-forming red alga, Corallina officinalis, with increasing tide pool depth and in pools of different surface area and at different tidal heights are presented for two similar shores in north Wales. Corallina turf supports a diverse assemblage of invertebrates achieving high densities of individuals which makes an important contribution to local biodiversity. Overall 123 different taxa were identified with the most dominant species being the polychaete Spirorbis corallinae and small individuals of the mussel Mytilus edulis. There are significant differences in the invertebrate assemblage at different depths in tide pools and higher diversity and richness at shallower depths nearer the edge of pools where the alga is shorter and more compact than at deeper depths. Pool size and tidal height were also clearly important in structuring the assemblage where there were significant differences in diversity, richness and assemblage pattern, although these differences were not consistent between shores. Some measures of habitat complexity, such as algal volume, correlate well with species richness, though occasionally diversity is negatively correlated with the number of holdfasts. Variations in physical conditions afforded by different depths and in tide pools of different size at different tidal heights at the scales measured clearly play an important role in structuring both the complexity of habitat and its associated assemblage

In the Mar Piccolo of Taranto (southern Italy, Mediterranean Sea), an enclosed basin with lagoonal features, Acanthophora nayadiformis is one of the major components of the free-living seaweed community to which the related attached population does not contribute consistently. Loose thalli of A. nayadiformis exhibit morphological features very different from those of the attached specimens and possess a peculiar vegetative cycle including an overwintering phase. Free-living morphs are characterized by monopodial stoloniferous growth; in contrast, both determinate and indeterminate branching as well as the typical ramisympodial growth pattern of the species are lacking. In autumn, free-living thalli fragment giving rise to stolon pieces which undergo deep structural changes in their sub-apical parts including both storage of floridean starch and extensive cortical thickening. Soon afterwards the uncorticated parts decay, whilst the modified fragments are able to overwinter and give rise to new fronds during next spring.

Exploration of the New England and Corner Rise Seamounts produced four new species of chrysogorgiid octocorals with the spiral iridogorgiid growth form. Three species are described as new in the genus Iridogorgia and one is described in the new genus Rhodaniridogorgia. Both genera have representatives in the Atlantic and Pacific Oceans. Iridogorgia magnispiralis sp. nov., is one of the largest octocorals encountered in the deep sea and seems to be widespread in the Atlantic.

This is the first study on coral diseases in the Wakatobi Marine National Park (WMNP), south-east Sulawesi. It aimed to provide baseline knowledge of coral disease prevalence and coral health in this remote region. Results indicate a low disease prevalence of 0.57% with only two known diseases occurring within the sampling unit, white syndrome (0.42%) and tumours (0.15%). They affected 15 taxonomic groups from a total of 32 taxonomic groups. The presence of black-band disease (BBD), skeletal eroding band (SEB) disease and Porites ulcerative white spot disease (PUWSD) was identified outside the study area. A large number of corals were affected by previously undescribed conditions (9.7% of colonies). The impact of lesions named as green spot, green band, pigmented spot, and flatworm infestation is not known and represents an important area for future studies.

This study analyses the possible relationships between body size and length of cnidae from different tissues of the sea anemone Oulactis muscosa. We describe the cnidom, providing new qualitative and quantitative data. Our description adds spirocysts for tentacles and acrorhagi, and is more precise about the ranges and types of basitrichs, microbasic b-mastigophores, and holotrichs. We distinguish two types of holotrichs in the acrorhagi, and differentiate between microbasic b-mastigophores and basitrichs in the actinopharynx and mesenterial filaments. A relationship between cnida length and body weight was not demonstrated. The results are based on a complete account of cnida types from all tissues, and considering the great number of capsules measured (5400) and the modern statistical tools employed, we think that a normal distribution of cnida lengths is uncommon, perhaps refuted. This finding is very important when a quantitative analysis of cnidae is necessary and an adequate statistical tool must be used. We have shown that generalized linear models are an alternative and therefore analyses can be done with parametric methods despite the non-normal distribution of cnida size. The use of these statistical tools should be generalized since appropriate package for analyses (like the R package) are available from the web and the obtained results are robust and powerful.

Tubiclavoides striatum, a new species of an athecate hydroid, was found on mud volcanoes, inactive carbonate chimneys, and cold-water coral stands in the Gulf of Cadiz (south-western Iberian Peninsula, Atlantic Ocean). The new family Tubiclavoididae and the new genus Tubiclavoides are proposed to accommodate the new species. The new hydroid is characterized by scattered filiform tentacles, sporosacs developing among the tentacles and hydrocauli covered with striated perisarc, often subdivided into imbricating cones. A full description and illustrations are provided, as well as some notes on the ecology and distribution of the new species.

A commensal relationship is described between the polyclad flatworm Paraprostatum echinolittorinae Faubel & Sluys gen. et sp. nov. and gastropod molluscs living on the Pacific coast of central America. Although the worms are relatively large in comparison with their hosts, the latter sustained no apparent damage. Considering the fact that the molluscs live in the upper eulittoral zone and littoral fringe of the shore, it is unlikely that the polyclads could survive for long outside the hosts. Diagnostic characters for the new genus and species are a long penial stylet joined to the proximal vesicle and absence of Lang's vesicle. It is pointed out that Aprostatum clippertoni Bock, 1913 and A. longipenis (Kato, 1943) have been incorrectly transferred to the genus Euplana Girard, 1893 and that Discoplana malagensis Doignon, Artois & Deheyn, 2003 should be transferred to the genus Ilyella Faubel, 1983.

Based on specimens collected in the Mediterranean and Red Sea coasts of Israel, the first lessepsian flatworm (Boninia neotethydis sp. nov.) is described. The genus Boninia includes cotylean polyclads characterized by the presence of multiple accessory (prostatoid) organs. The three species described are distributed in the western Pacific (B. mirabilis) and in the Caribbean (B. antillarum and B. divae). The new species differ from congenerics in the number and arrangement of the prostatoid organs, and in the number of marginal eyes. Specimens of the new species feed on mussels, and their possible effects on Mediterranean mussel cultures should be monitored.

Platynereis dumerilii is an emerging model system for both comparative developmental biology and ecotoxicology. As such it would be extremely valuable to be able to map the location of genes and markers in its genome, in order to understand how the genome changes or has changed, either due to chemical and environmental insults or during evolution. Here we report the adaptation of the technique of chromosomal fluorescence in situ hybridization (FISH) to P. dumerilii for the localization of single-copy genes. Also the duplicated ribosomal gene cluster of this annelid is more reliably revealed with FISH than with the previous technique of silver staining. This duplicated ribosomal cluster correlates with polymorphisms in the internal transcribed spacer (ITS) regions, which has implications for the use of these regions in phylogenetic or population biology work.

The examination of rock and stone samples collected at 0.2–3 m in Mersin Bay (Levantine coast of Turkey) revealed the presence of 14 specimens belonging to a new species of Syllidae (Polychaeta), Trypanosyllis sanmartini. The species is mainly characterized by having dark reddish-brown dorsal cirri, pale yellowish body colour, weakly bidentate falcigers, long and filiform dorsal cirri, long proventricle and pharynx, and a trepan with ten large teeth (without a pharyngeal mid-dorsal tooth). The posterior-most segments of the holotype and five paratypes had a cluster of stolons. The morphology and reproductive features of the species are explained and discussed.

The aerobic and anaerobic metabolism of Paraprionospio pinnata were estimated under laboratory conditions. Paraprionospio pinnata is a widely distributed, often dominant polychaete inhabiting sublittoral sediments on the continental shelf off central Chile, where there is a pronounced oxygen minimum zone (OMZ). The aerobic respiration rates ranged from 0.25 to 1.28 ml O2 h-1 g-1 dry weight. Paraprionospio pinnata displayed oxyconformity between 30 mm Hg (4 kPa) and 104 mm Hg (14 kPa) of oxygen tension levels (pO2) under laboratory conditions. We found that P. pinnata is an aerobic oxygen conformer and is able to endure very low oxygen conditions. High anaerobic activity of alanopine dehydrogenase (5.74 ±1.20 μmol NADH min-1 g-1 wet weight) and strombine dehydrogenase (8.82 ±4.04 μmol NADH min-1 g-1 wet weight) were observed. The ratio between the calculated aerobic respiration rates and the electron transfer system activity were 0.28 and 0.12 for normoxic and hypoxic conditions, respectively. Based on the observed respiration rates and the average densities of P. pinnata in the study site, we estimated the population carbon flux via aerobic respiration to be about 32 mg C m-2 d-1 in spring and 80 mg C m-2 d-1 in winter. Paraprionospio pinnata would be using, then, about 8.6% of the total downward flux of organic carbon to the seabed and contributing between 18 and 44% of the total sediment community oxygen consumption.

Chauvinelia contains two abyssal species, C. biscayensis, and C. arctica. Because of the lack of some relevant details in the original descriptions, they are redescribed, the generic diagnosis is emended, and a key to separate them is included. Flabelliseta incrusta and Helmetophorus rankini, the type and only species for these genera are redescribed; they lack annulated or multi-articulated capillaries, their chaetae have a detachable cortex carrying successive rows of tiny spines, and they share several features with Chauvinelia. Therefore Flabelliseta, and Helmetophorus, currently regarded as members of Flabelligeridae de Saint-Joseph, 1894, are transferred to the Acrocirridae Banse, 1969. Consequently the family diagnosis is emended to include simple capillary neurochaetae, and a key for all acrocirrid genera is also included.

Egg development time and hatching success were determined for the oncaeid copepod, Triconia canadensis, from the mesopelagic zone of the western subarctic Pacific. The egg development time was estimated to be 74.7–84.5 days at in situ temperature (3°C), which is much longer than those reported previously on the other oncaeid copepods even if the differences in experimental temperatures are taken into account. The egg hatching success varied between 50 and 100%, with a grand mean of 88%. The newly hatched nauplii of T. canadensis were elongate ellipsoid in shape, and had many large-sized lipid droplets in their body. Possible adaptive significance of apparent longer egg developmment time of T. canadensis is discussed in the light of their life cycle strategy.

Wedding shrimps, Spongicoloides koehleri, spend the adult phase of their life cycle within the cavity of a hexactinellid sponge. Although there is little light at the depths at which the sponges are found, the shrimps do not use the highly sensitive reflecting superposition optics commonly found in other shrimp-like decapods. Instead they have apposition eyes which are virtually free of shielding pigment. It is proposed that this is due to the paedomorphic retention of the larval optics through the process of neoteny.

Many warm-water (Lusitanian) species reach their limits in the central English Channel, failing to penetrate to the North Sea. We re-surveyed the eastern limits of the Lusitanian intertidal barnacles Chthamalus montagui and C. stellatus, from 1994 to 2004, a decade of exceptionally high sea temperatures, and found range extensions on both sides of the Channel compared to the 1950s and 1970s. Annual recruitment of Chthamalus on the English coast was monitored. There was a consistent gradient of low recruitment to the east of Portland Bill, with significant reductions coinciding with prominent headlands. Highest recruitment occurred during the warmest years. Cluster analysis showed a high degree of similarity of annual recruitment within coastal cells suggesting that local processes are also important. In 1999 we compared recruitment in the other common intertidal barnacles, the boreal Semibalanus balanoides and the non-native Elminius modestus, with Chthamalus spp. All species showed low recruitment between Selsey Bill and Portland Bill, suggesting habitat limitations and/or hydrographic mechanisms. Annual recruitment of Chthamalus at existing limits on the Isle of Wight was positively correlated with the number of days of westerly and south-westerly winds during the summer, coinciding with the pelagic larval phase. A ‘pulse’ of high Chthamalus recruitment on the Isle of Wight, measured during the summer of 2000, reversed population decline. Only a higher frequency of such pulses will maintain populations at existing limits and increase the rate of range extension towards the North Sea. Such extension will be limited by lack of hard substrata, but proliferation of coastal defence schemes in recent years is increasing suitable habitat for barnacles.

Mysids are common and abundant organisms in estuaries and coastal waters, where they have a central role in the functioning of food webs. The Río de la Plata (RdlP) is a major estuary that affects biogeographic patterns of marine coastal organisms in the south-west Atlantic, but studies of the plankton in the RdlP are scarce. Knowledge of the mysid fauna in particular is very limited with a single species (likely alien, Neomysis americana), traditionally known to inhabit this 38,000 km2 estuary, and a second one, Mysidopsis tortonesei, only recently reported. The purpose of this paper is to contribute with the knowledge of the mysid fauna of this ecosystem by exploring the spatial distribution and in situ salinity preferences of N. americana and M. tortonesei in the mixohaline region of the RdlP during austral autumn, 2001. Both species showed clear and contrasting haline affinities that resulted in an almost perfect spatial segregation within the study area. Neomysis americana occurred preferentially in oligo- and meso-haline conditions (range <1 to 33.37, but most abundant at salinities <28), while M. tortonesei occurred at salinities >28. Temperature range was quite narrow and it was unlikely that it affected mysid distribution in the estuary. Temporal variability in observed patterns, as well as the role of biological interactions in shaping spatial distribution of N. americana and M. tortonesei within the estuary are subjects that deserve further attention in future studies.

Successful management of fishery resources is dependent on understanding the exploited species' reproductive potential, which, in turn, requires spatially relevant estimates of the size at maturity and the size–fecundity relationship. This information is used by fisheries managers to implement regional maturity-based legal landings sizes and seasonal fishery closures aimed at protecting the spawning stock and maintaining the reproductive output of the fished population at a sustainable level, despite exploitation. Crab fisheries in particular depend on such information, which is often limited, even in long-established fisheries. To address this issue, size–fecundity relationships were obtained for two commercially exploited crabs in waters around the Shetland Islands (60°N 01°W). These species were Cancer pagurus and Necora puber. A statistically significant positive size–fecundity relationship was found for C. pagurus which describes a mean reproduction potential ranging from ~0.78 million eggs in females of 129 mm carapace width (CW) to ~2.4 million eggs in females of 212 mm CW. The positive size–fecundity relationship found for N. puber was not statistically significant, but describes a mean reproduction potential ranging from ~0.16 million eggs in females of 56 mm CW to ~0.19 million eggs in females of 96 mm CW. Morphometric assessments of reproductive capacity in C. pagurus support the notion that positive size–fecundity relationships are attributable to the combined capacities of specific morphological features, each of which contributes to a female's spawning output ability. Statistically significant positive linear relationships were found between the natural logarithms of crab size (CW) and pleopod capacity, sperm plug mass, spermathecae capacity and gonad capacity. Respectively, these structures are crucial for successful egg attachment and incubation, sperm retention and protection, sperm storage and oogenesis.

We compared the reproductive behaviours of two protandric simultaneous hermaphroditic species (Lysmata amboinensis and L. boggessi) that belong to two groups of Lysmata shrimp with different morphology, geographical distribution, and density. Lysmata amboinensis occurs in tropical waters at low population densities, and L. boggessi is found in aggregation in sub-tropical and temperate areas. Reproductive behaviour of L. boggessi under two densities and L. amboinensis in different habitats were compared. Results show that L. amboinensis was much less active during mating than L. boggessi. Male shrimp of L. amboinensis did not display obvious pre-copulation behaviour. They also took significantly longer to transfer spermatophores and lay eggs after mating than L. boggessi shrimp did. For L. boggessi, moulting time of female shrimp, copulation time and the interval between moulting and mating were significantly shorter when three male shrimp were present than when only one male shrimp was present. Our study suggests that the reproductive behavioural differences in the two shrimp species are possibly the results of density-dependent effect.

Porcelain crabs live in dense aggregations under boulders in the intertidal zone of northern Chile. A quantitative approach was performed to examine the distribution patterns of dominant species and to correlate it with emersion and temperature under the boulders. The study involved six tidal levels across the intertidal with six replicates each, totalling 36 samples of 0.09 m2. From the seven species found, Petrolisthes granulosus, P. violaceus and Allopetrolisthes angulosus took in 49.06%, 25.20% and 25.51% respectively, of the total number of individuals collected (N=10,631). The distribution patterns showed P. granulosus dominating in the upper levels (up to 73% of emersion and 22°C), P. granulosus and P. violaceus coexisting in the middle levels (48% of emersion and 21.6°C), and A. angulosus dominating in the lower levels (below 20% of emersion and 17.8°C). Size distribution for P. granulosus declined at its limit levels of distribution, the same tendency appeared at the upper limits of P. violaceus and A. angulosus. Temperature and emersion gradients strongly affected the species richness, abundance and mean size of the species across the intertidal, thus clearly influencing the occurrence and distribution patterns of the species studied. The ability of the upper-middle shore species to tolerate high levels of temperature and emersion is suggested to explain their distribution patterns. Size distribution differences might have been caused by biological interactions as intra and interspecific competition. A foregut content analysis revealed trophic differences among the dominant species, a result that could be related to the distribution.