Comparative studies were conducted on intertidal algal and faunal communities associated with Sargassum muticum and native algae on the Isle of Cumbrae, Scotland. Significant differences were detected in the structure and composition of the communities. The abundance of the dominant native algae Dictyota dichotoma was found to be reduced in areas dominated by S. muticum and displacement through competition for substrate or light is inferred. Elevated faunal abundances were associated with S. muticum and evidence indicates that increased detrital input may be a possible contributory factor. Differences in faunal community composition were most pronounced in the sessile epifauna below the S. muticum canopy. Faunal communities associated with S. muticum were less heterogeneous in composition than those associated with native algae at equivalent shore positions. Some of the compositional differences may be coincidental and attributable to factors favouring the establishment of S. muticum rather than to the direct influence of the S. muticum canopy.

The distribution and abundance of intertidal organisms can be affected by short-term events, such as rain. We compared the effects of rain on intertidal mobile invertebrates in four common microhabitats with differing amounts of shelter (namely beds of oysters, coralline turf, bare patches and crevices) on sea walls in Sydney Harbour. There was an effect of rain on some, but not all taxa, although this was not consistent between locations or times. Effects of rain were observed for some species of gastropods and crustaceans, but not for polychaetes. Manipulative experiments using artificial rain indicated that rain, without the presence of run-off and independent of potential temporal confounding from differences in weather conditions, has a negative effect on abundances of amphipods in coralline turf. Pulse responses by mobile organisms to short-term rain events should be considered when designing experiments looking at temporal variability and processes responsible for observed patterns of distribution of marine organisms.

Here we report the first direct underwater observations of extensive human-caused impacts on two remote seamounts in the Corner Rise complex (north-western Atlantic). This note documents evidence of anthropogenic damage on the summits of Kükenthal peak (on Corner Seamount) and Yakutat Seamount, likely resulting from a limited Russian fishery from the mid-1970s to the mid-1990s, highlighting how bottom trawling can have long-term detrimental effects on deep-water benthic fauna.

Marine invertebrate larvae represent a transitory, but nonetheless important component of planktonic communities. Assessing their contribution to plankton diversity has been hindered by numerous methodological difficulties, notably at the identification step. For many sessile invertebrates, planktonic larvae also play a crucial role, as they are their sole dispersal vectors. Understanding connectivity patterns among marine populations is fundamental for managing coastal ecosystems and their associated resources. Indirect approaches, relying on population genetics models, have widely contributed to elucidate population structure and gene flow patterns, but show, in some cases, conflicting results with larval dispersal potential. In an attempt to facilitate surveys of larval distributions and abundances, an in situ hybridization on whole larvae method was tested over a range of marine invertebrate larvae collected from environmental plankton samples. Ribosomal RNA-targeted oligonucleotide probes were used for hybridization, followed by a colorimetric reaction allowing signal detection at the light microscope. Promising results were obtained, showing an unambiguous positive hybridization signal with a eukaryotic (positive) probe, but no signal with a negative probe. Using species-specific probes, the method could be applied to resolve key current questions in marine ecology, addressing both wide and fine scales.

The morphology and infraciliature of a new marine ciliate, Tachysoma multinucleata sp. nov., collected from the Jawol Island near Incheon, Korea, were investigated using live observation and protargol impregnation. The new species is characterized by: size in vivo about 65×25 μm, body oval to ellipsoid. Three frontal, one buccal, four frontoventral, three ventral and two pretransverse cirri. Fifteen to 22 left and 13–21 right marginal cirri and about 21–27 adoral membranelles. Cortical granules fine and yellowish, arranged around cirri and dorsal cilia. Usually 12–26 macronuclear nodules. Three dorsal kineties. Marine habitat.

The effects of the exposure of two tintinnids (Favella taraikaensis and Eutintinnus sp.) to the toxic dinoflagellate Alexandrium tamarense were studied, using the non-toxic dinoflagellate Scrippsiella trochoidea as a control. The tintinnid F. taraikaensis showed backward swimming and cellular lysis after a few minutes in the presence of the toxic dinoflagellate A. tamarense in high concentration (280–700 cells ml-1). At low concentrations of A. tamarense (30–120 cells ml-1) no swimming alterations were observed, but cellular lysis occurred after 48 hours. No changes in the swimming patterns were observed when Eutintinnus sp. was exposed to either toxic dinoflagellates or cell-free filtrate, or when F. taraikaensis was exposed to cell-free filtrate. However, both tintinnids suffered cellular lysis after 48 hours of exposure. Favella taraikaensis and Eutintinnus sp. remained healthy after preying on the non-toxic S. trochoidea for 48 hours. In selectivity experiments, F. taraikaensis avoided cells of the toxic dinoflagellates during the dark phase. Our results suggest that tintinnids could play a regulatory role when the toxic blooms are initiating and the toxic cell concentrations remain still low in the northern Patagonian gulfs of Argentina. Since tintinnids are affected by substances released by A. tamarense, predation on dinoflagellates would not occur during the peak of the bloom.

The aim of the present study was to update the existing knowledge of benthic hydroids from Svalbard waters. The material for the study was collected at several locations in the Svalbard region. The list of hydropolyps from the investigated area includes about 100 species. A total of 42 taxa was noted in the present study, 18 of which were reported for the first time in this area. One species is likely new to science. The analyses address the zoogeographical status of the species and the diversity of microhabitats. Arctic-boreal species were the main component of the hydroid assemblage, and eight types of substrata were colonized by the hydroids. Their highest biodiversity occurred on algae and bryozoans. Biological studies and faunal records used to monitor the Arctic region are of increasing importance in light of climate change and its influence on benthic community structure.

The distributions of the pennatulid anthozoans (sea pens) Virgularia mirabilis, Pennatula phosphorea and Funiculina quadrangularis in Scottish waters have previously only been extensively documented in sea lochs, by the Marine Nature Conservation Review (MNCR) surveys. Funiculina quadrangularis in particular was thought to be restricted to the deep basins of sea lochs and is classified as a nationally uncommon species. Sea pens are characterizing species in seven biotopes found in Scottish waters and are protected under the ‘Mud in Deep Water Habitat Action Plan’ of the UK Biodiversity Action Plan (UKBAP) and are also recorded in several Special Areas of Conservation. The present study has extended the existing information available on sea pens in Scottish waters. The distribution and abundance of the three sea pen species were mapped using GIS (Geographical Information System) by utilizing data from Nephrops norvegicus stock assessment video surveys carried out by Fisheries Research Services (FRS) Marine Laboratory. Distribution was shown to be aggregated for all species. Funiculina quadrangularis was present in areas outside the sea lochs, such as the South Minch and the outer mouths of most sea lochs. This study demonstrates that analysis of video footage derived from Nephrops stock assessment surveys can significantly extend our knowledge of sea pen distribution and population density. Future management of Nephrops stocks can be expected to consider impacts of fishing on non-commercial species such as sea pens as a part of the ‘ecosystem approach’ to management.

Two new species of rotifers belonging to the Dicranophoridae are described from marine psammon collected at a depth of 30–40 m in the Mediterranean near the island of Elba, Italy. Myersinella uncodonta sp. nov. is characterized by two colourless eyespots; single, incurved acute apical rami teeth; two needle-shaped, slightly incurved elongate unci; manubria with forked head and crutched cauda; outer margin of rami angular postero-laterally. Myersinella longiforceps sp. nov. is characterized by two large red eyespots; a pair of extremely elongated, gouge-shaped apical rami teeth; two short, needle-shaped unci; manubria with forked head and double-crutched cauda; outer margin of rami rounded laterally, tapering towards fulcrum. This is the first report of the genus Myersinella from marine environments.

Geographical information system analysis was applied to assist in the re-identification of records of Chaetozone setosa from the north-east Atlantic. Previously this species was considered to have a world-wide distribution. The aim of this study is to clarify and illustrate the distribution patterns associated with sediment and water characteristics of C. setosa and other Chaetozone species.

A behavioural assay based on a ‘homosexual’ response in males has revealed that female Harmothoe imbricata release a substance that induces pair formation. Extracts from unfertilized spawned oocytes (diameter approximately 120 μm), but not sub-mature oocytes (90 μm diameter) removed directly from the coelomic cavity, have significant pair formation-inducing activity in comparison to the control. Preliminary results indicate that the substance is stable under standard purification techniques and larger than 10 kDa, as well as being heat and trypsin insensitive.

A new species of Synelmis (Annelida: Polychaeta: Pilargidae), Synelmis urgorrii sp. nov., is described from the continental slope off north-western Spain. The new species is characterized by having antennae, peristomial cirri and parapodial cirri cirriform, lateral antennae located in the proximal third of the prostomium, notospines starting on chaetigers 7–11, well-developed neuropodial lobe and asymmetrical furcate chaetae, those of anterior chaetigers distinctly spinulated.

Intra- and interspecific variation in a 658 bp long part of the cytochrome c oxidase subunit 1 (COI) gene of the mitochondrial genome, i.e. a suggested ‘DNA barcode’, was assessed in four north-west European species of the marine tubificid genus Tubificoides: T. benedii, T. amplivasatus, T. heterochaetus and T. kozloffi. Within species mean genetic distance was from 0.10% (T. amplivasatus) to 0.14% (T. benedii), between species from 19.3% to 22.9%. For T. benedii and T. amplivasatus, material collected in two separate areas, The Sound between Denmark and Sweden, and the Koster area about 330 km to the north along the Swedish west coast, showed a geographically random distribution of COI haplotypes, suggesting that each of these two species forms a continuous population in southern Scandinavia. We conclude that the COI gene is suitable as a barcode marker for the secure identification of these species, at least within the area investigated. Tubificoides heterochaetus is reported for the first time from Denmark.

One hundred and four specimens of Branchiomma luctuosum (Grube, 1870), a sabellid polychaete, were submitted to different anaesthetization and fixation procedures: a control group with living animals, immediate fixation with formaldehyde 4% (FO), ethanol 100% (AE) or ethanol 70% (ET), and anaesthetization with magnesium chloride (MC), refrigeration (RE), menthol crystals (ME) or freshwater (FW). Twenty-three morphometric variables of the body were measured and analysed with size-free multivariate statistics. The first three canonical variables explained 80% of the variation, being significantly correlated with 19 measured variables, mainly those related to the shape of the body setigers. Besides morphometric variables, some morphological characters commonly used in polychaete taxonomy also presented variation among fixation procedures, such as the release of parapodial elements and the integument. Among the procedures tested, AE, ET and FW were the best in approximating the shape of living specimens. Specimens submitted to FO and RE had shorter, wider, and thicker bodies, whereas those submitted to MC and ME were more elongated, narrower, flatter, and had wider pygidia than living specimens. Lengths of branchial crown, setiger 1 and pygidium seem to be the most informative morphometric characters for taxonomic purposes since they did not present deformation due to fixation procedures.

Four new species of cheilostome Bryozoa from the hippothoid genus Antarctothoa (formerly subgenus Antarctothoa, Moyano 1987) are described. Antarctothoa bougainvillei (d'Orbigny) and Antarctothoa dictyota (Hayward) are re-described from material collected from Patagonia and South Georgia respectively.

The ecology and biogeography of meiofauna at deep-sea hydrothermal vents have historically received less attention than those of mega- and macrofauna. This study examines the composition of major meiofaunal taxa in beds of the mussel Bathymodiolus thermophilus at hydrothermal vents on the northern and southern East Pacific Rise (EPR) and presents the first comparison of species assemblages of the dominant taxon, the nematodes, among sites spanning 27 degrees of latitude. Meiofaunal samples were collected by submersible from three mussel beds at 9°N on the EPR and four mussel beds between 17 and 18°S in 1999. Estimated ages of the mussel beds at the time of sampling range from 4 to >20 years, enabling investigation of the influence of mussel bed age on meiofaunal assemblages. Overall, the meiofauna of the mussel beds was dominated by nematodes, with copepods constituting the second most abundant meiofaunal group. There was variation in the ratio of nematodes to copepods between sites, however, with copepods more abundant than nematodes in the youngest mussel beds. Apart from polychaete larvae, other meiofaunal groups were generally present at very low abundance (<1%) in the samples and restricted in diversity to gastropod larvae, acari, foraminifera, ostracoda and turbellaria. Seventeen nematode species from 14 genera and 11 families were found in the samples, with no evidence of endemicity to hydrothermal vents at the generic level. Four genera present were not previously recorded at hydrothermal vents. Nematode species richness, species:genus ratios and abundances were low compared with other deep-sea habitats, though the ecological relevance of comparisons with soft-sediment benthos is discussed. Nematode assemblages exhibited high dominance by a few species, with one species of Thalassomonhystera most abundant at five of the seven vent sites. Multivariate analysis of nematode assemblages reveals similarities among sites that do not match geographical proximity. The youngest mussel beds were most similar to each other and exhibited lower species richness than other sites, consistent with colonization of mussel bed habitat by nematodes over time. Similarity in the composition of nematode assemblages among sites separated by ~3000 km indicates that they lie within a single biogeographic province, consistent with that proposed for mussel bed macrofauna. At a generic level, samples exhibited some overlap with nematode assemblages at vents elsewhere on the EPR, on the Mid Atlantic Ridge and in the North Fiji Basin.

This article is a review of the genus Richtersia (Nematoda: Selachinematidae) with a key to species, genus diagnosis and lists of valid species. Two new Richtersia species from the Golfo San José and Golfo San Matías, Chubut province of Argentina are described: Richtersia bicornis sp. nov. is characterized by having two thorn structures after cuticular collar, and in total 32–40 longitudinal rows of spines arranged in eight groups in cervical region and precloacal spines similar in shape. Richtersia argentinae sp. nov. is characterized by the number of longitudinal rows of spines, amphid size and the precloacal spines configuration.

Seasonality of the reproductive cycle for Necora puber was determined using three biological indicators: extruding sperm plugs (mating period), extrusion of eggs (spawning period) and presence of empty egg capsules (hatching period). Sperm plugs were found only in recently moulted females, indicating that mating coincides with moulting periods. Necora puber mating indicators were observed during the summer months and into autumn; spawning was observed year-round but peaked in the summer; hatching was observed throughout the summer into late autumn. Size at maturity was assessed using a variety of reproductive and morphometric criteria; estimates from reproductive criteria are generally larger than those from morphometric criteria and these differences are often indicative of ‘functional’ vs ‘behavioural’ maturity. Size at maturity estimates for N. puber in Shetland ranged from 40.0–49.9 mm CW in males and 51.8–59.5 mm CW in females; sizes at functional maturity were larger than sizes derived from morphometric indicators.

Lysmata wurdemanni is a protandric-simultaneous hermaphroditic shrimp. Individuals reproduce as males first and late in life as simultaneous hermaphrodites. I examined whether sex allocation (resources devoted to ova vs sperm) varies with group size in shrimps that have just matured as hermaphrodites. Focal males were reared with different numbers of hermaphrodites (1, 2, 5 or 10). Sperm stored in the ejaculatory ducts and eggs brooded underneath the abdomen were retrieved and weighted immediately after focal shrimps matured as hermaphrodites. Hermaphrodites should invest more into sperm with increasing group size to cope with more intense sperm competition. The proportion of focal shrimps that lost their first clutch of eggs after maturing as hermaphrodites increased with group size. This suggests male gender preferences by hermaphrodites experiencing large group sizes. No differences in sex allocation among group sizes were recorded for shrimps that did not lose their first clutch of eggs. Thus, group size does not affect sex allocation in terms of ova and sperm mass. This lack of phenotypic plasticity might be explained if sperm competition is not important in L. wurdemanni. It should not pay in terms of fitness for shrimps to produce and inseminate female-role hermaphrodites with large amounts of sperm when full paternity is assured in the absence of multi-male mating. In agreement with this idea, a second experiment demonstrated that female-role hermaphrodites invariably mated only once with a single other shrimp.

The activity rhythm of the cold seep shrimp Alvinocaris stactophila from the Gulf of Mexico slope (650 m depth) was investigated in the laboratory in relation to an artificial 12 h light-dark regime. Animals were sampled with a submersible and transferred into individual aquaria where their activity was monitored for 5 d by taking digital video snapshots every 30 s. An observer analysed the footage by counting the number of times an animal crossed two perpendicular lines drawn on a PC screen per 30 min interval. Resulting time series were represented over consecutive days and the waveform analysis was used to precisely assess the phase (i.e. the peak timing) and its limits (i.e. onset and offset) in relation to light ON and OFF. The majority (73%) of animals showed a marked nocturnal pattern of activity with number of movements close to zero during the photophase. Waveform analysis showed that the behavioural transition from activity to inactivity after light ON occurred within approximately 1 h. Considering the general lack of knowledge on the regulation of activity rhythms of crustaceans from subtidal areas, the present data provide a new insight on the role played by light in the regulation of animal activity rhythm in deep-water environments such as those of the cold seeps in the Gulf of Mexico.