The quantum yield and photosynthetic parameters of phytoplankton and sea ice microalgal communities were assessed from the Arctic Ocean and fjords of northern Svalbard. The phytoplankton community in Fram Strait was dominated by Phaeocystis while on Norskebanken it was dominated by diatoms. The quantum yield showed maximum values of 0·64 at 20–40 m below the surface and were consistent with nutrient replete waters elsewhere.

Sea ice infiltration communities were widespread and dominated by Phaeocystis. This is the first record of an Arctic infiltration ice community. Quantum yields were relatively low (0·247). Bottom ice communities, which were dominated by Nitzschia frigida, were extremely restricted and had moderate quantum yields (0·427). Communities growing on multiyear ice had quantum yields of only 0·126. All ice communities were well adapted to their light environment.

Since the incursions of the introduced green macroalgae Codium fragile ssp. tomentosoides and ssp. atlanticum on European shores, the abundance and distribution of the native congeners C. tomentosum and C. vermilara have come under closer scrutiny. Hypotheses regarding the reported declines in the native(s) are largely speculative due to the paucity of quantitative information on the natives, the cryptic nature of the invaders and the unknown processes regulating Codium assemblages. As part of a field-based Codium study on north-eastern Atlantic shores, our surveys on Guernsey shores, Channel Islands, in September 2002 have revealed two unexpected and noteworthy results: (1) thriving populations of C. tomentosum are quite abundant on mid to low littoral shores; and (2) in marked contrast, sparse populations of C. fragile ssp. tomentosoides are restricted primarily to upper mid-littoral rock pools. Native Codium has not been displaced or eliminated from the southern end of the British Isles.

Subtidal macroalgal assemblages differed among islands within the Recherche Archipelago, Western Australia, with respect to species biomass. To investigate whether macroalgal populations were maintained locally, settlement plates were moored in 10 to 15 m depths at a reef sampled for macroalgal diversity, and 20, 50, 100, and 500 m away from the reef. Plates were retrieved after eight months and assemblage differences were compared with distance from the sampled reef. Macroalgal richness decreased with distance from an island assemblage and molluscan richness increased. At 500 m away, the number of algal recruits was negligible and the number of bivalves was relatively high.

This study investigated the synchrony of frond dynamics among patches of the intertidal seaweed Mazzaella parksii (=M. cornucopiae; Rhodophyta: Gigartinales) at local spatial scale. At Prasiola Point (Pacific coast of Canada), the mean synchrony of the seasonal changes in frond density among seven permanent, 100-cm2 quadrats was significant (mean Pearson's r=0·73, with 0·65–0·81 as 95% confidence limits) between 1993 and 1995. This indicates that predicting seasonal trends for non-monitored patches at local spatial scale can be done relatively well based on observations on a limited number of quadrats. The identification of the spatial scales at which seaweed populations covary synchronously will permit minimizing sampling effort while retaining the ability to make valid predictions for non-monitored sites.

Changes in O2 concentration were measured during in situ incubation of whole, young Laminaria hyperborea and used to evaluate primary production and respiration over a 3-y period (1995–1998). The exudation of dissolved organic carbon (DOC) during incubation was also measured. Total carbohydrates and polyphenols in the exudates and the regional seawater were determined and fractionated into low molecular weight (LMW) and high molecular weight (HMW) species.  Net production rates varied significantly, being highest during the growth phase (March), while respiration rates did not vary significantly. The exudation rates correlated with the plant strategy of growth and production in which high requirements for growth led to a lower proportion of fixed carbon being exuded. More fixed carbon was exuded during the non-growth phase. The annual exudation of DOC is estimated to be ∼26% of fixed carbon and amounts to ∼1·29 kgC m−2 y−1. The annual amount of carbon retained by the kelp (the difference between fixed and exuded carbon), assumed to contribute to growth, corresponds to a biomass increase of 3·0 kgC m−2 y−1, a value similar to those reported using direct measurements of biomass increase in the region.  Carbohydrate concentrations in the exudates were lower during March than in other months, in accordance with the plant growth strategy. Phenols, on the other hand, which are assumed to function as predator deterrent, showed no significant variations in the exudate. The fraction is dominated by carbohydrates while phenols occurred mainly in the LMW fractions.

The occurrence of morpho-chronological variations was demonstrated in three Australian species of phanerogams, Posidonia australis, Posidonia coriacea and Posidonia sinuosa, which are found living around Rottnest Island (Western Australia). Three chronological parameters were identified: the thickness of dead sheaths, the internodal distance and the regular presence of floral stalk remains. The foliar primary production for these three species, as estimated using the lepidochronology method, is very high since values of 1374, 1811 and 678 mg dw shoot−1 y−1 were recorded, respectively. Rhizome production values range from 70·6 and 376·7 mg dw shoot−1 y−1 for Posidonia coriacea and Posidonia australis respectively. The results obtained are very encouraging and confirm that these morpho-chronological variations are particularly well developed for the genus Posidonia.

We evaluated experimentally whether distance between patches of the brown alga Sargassum stenophyllum relative to the source of colonizers influenced colonization patterns by (1) mobile epifauna and (2) gammarid amphipods with distinct life habits. Amphipods were the dominant group, commonly dispersing to patches up to 8 m distant from the algal bed, with low densities of other faunal groups. Assemblage structure of both faunal groups and gammarid amphipods on defaunated algae generally converged to that of controls during the experiments in less than eight days. Gammarid amphipods were dominated by tube-dwellers, but free-living nestlers also colonized the available substrate, and both reached control densities during the study. The same pattern was observed for representative species within each group. Colonization rates were related to faunal densities on the algal bed for most groups, suggesting that mobile organisms disperse more to new habitat patches in high density conditions. Thus, species with direct development can rapidly establish new aggregations at favourable sites, and contribute to small-scale heterogeneity in faunal distribution.

Caprella spp. (Crustacea: Amphipoda) inhabiting the Sargassum algal community in Otsuchi Bay near unpopulated areas of northern Japan, were collected from 1994 to 2001 and subjected to analysis of butyltin (BT) concentrations. The period from 1994 to 2001 corresponds to four to 11 years after legislation limiting the use of tributyltin (TBT) on small boats and aquaculture facilities was passed in Japan. Butyltin compounds including TBT, dibutyltin (DBT) and monobutyltin (MBT) were detected in all samples of Caprella spp., although the three BTs were not detected in seawater samples collected from the same area between 1997 and 1999. The concentration of total BTs (BTs=MBT+DBT+TBT) in Caprella spp. significantly decreased from 84 ng BTs/g wet wt in 1994 to 7·4 ng/g wet wt in 2001. The concentrations of BTs in Caprella spp., which have a high bioconcentration factor for TBT, are thought to reflect the average concentrations of BTs in the surrounding seawater in the previous few months. The half-life of BTs and TBT in Caprella spp. was 2·38 years and 2·07 years, respectively, which are less than half of that of TBT in seawater based on the national survey of The Ministry of the Environment, Japan. Illegal usage of TBT near the studied area may have decreased due to monitoring of BTs.

Conqueria laevis gen. and sp. nov., a new monothalamous agglutinated foraminiferan, is described from core samples collected in the abyssal western Weddell Sea. The species is characterized by a very elongate, almost cylindrical test that usually follows a more or less curved course and has a single terminal aperture located at the end of a short neck. The wall has a very smooth outer surface and is composed of tiny (<5 μm) agglutinated particles. Very similar and presumably congeneric morphotypes occur at northern hemisphere sites, including Arctic fjords around Svalbard and the Porcupine Abyssal Plain. Molecular phylogenetic analyses, based on small subunit rRNA gene sequences, indicate that the new Weddell Sea species forms an independent lineage branching among monothalamous foraminiferans as a sister group to the clade of Psammophaga.

A species of the genus Amorphinopsis is described for the first time for the Atlantic Ocean. The new species was described based on the study of 25 specimens, collected in the area of the São Sebastião Channel and its environs (northern sector of São Paulo State coastline) and in the Cabo Frio region (Rio de Janeiro State). The form is massive cushion-shaped, lobate, occasionally encrusting. The megascleres are styles [160–260 (N=20)/5–10 (N=10) μm; length/thickness] and oxeas [150–900 (N=100)/5–18 (N=20) μm]. Amorphinopsis atlantica sp. nov. differs from the other species of Amorphinopsis by its colour, dark-greyish-green with or without yellow tinges on the exposed surface, and the smaller size of its oxeas. Amorphinopsis excavans is the closest species to the Brazilian material, but can still be set apart by a series of smaller traits, such as oxeas and styles never overlapping (the smaller oxea is always larger than the larger style).

The identification of most soft-bodied hexacorals requires morphological and histological examinations of preserved specimens and experience for correct interpretation of the observed features. Poorly preserved or damaged material resulting from improper sampling complicates identification. In many cases the characteristics of the preserved specimens alone do not lead to satisfying results. Living specimens, however, exhibit numerous characteristics which would often allow identification, even in the field. However, most of these characteristics get lost during preservation. Modern techniques and advances in sampling methods allow the acquisition and preservation of a lot of information on the living animal and its habitat.

Using Chilean sea anemone species, it is demonstrated how the work with specimens in situ and in vivo can help with identification and reveal important morphological–taxonomical, biological, and ecological information. Whenever possible, this information should be part of species descriptions and should be used to create detailed, reliable, tabular identification keys for the laboratory and field. The examples illustrate the urgent need for modern, comparable re-descriptions. In most parts the protocol also applies to other soft-bodied hexacorals.

The discovery of the association between the sponge Desmapsamma anchorata (Demospongiae: Poecilosclerida: Desmacididae) and the octocoral Carijoa riisei (Cnidaria: Alcyonacea: Clavularidae) on an Indonesian reef enlarges the widespread dispersion of these Atlantic species in the Indo-Pacific area. The species involved and their morphological adaptations resulting from the association are described. When covered by the sponge, C. riisei develops an irregular branching pattern and a dense nematocyst layer where the ectoderm comes in contact with the sponge tissue. The finding of fertile colonies suggests that the Indonesian population of C. riisei is self-sustaining.

Distichopora robusta, the first shallow-water stylasterid coral from the tropical eastern Pacific, is described from the west coast of Panama. The new species is distinguished from all species of Distichopora described thus far by having robust branches and poorly defined pore rows.

The integration of molecular and morphological approaches has produced substantial progress in understanding the higher classification of most major invertebrate groups. The striking exception to this is the Polychaeta. Neither the membership nor the higher classification of this group has been robustly established. Major inconsistencies exist between the only comprehensive cladistic analysis of Polychaeta using morphological data and the DNA sequence studies covering all or part of the taxon.

We have compiled a dataset of available nearly complete 18S ribosomal DNA sequences and collected an additional 22 sequences (20 Polychaeta in 19 taxa, one Myzostomida and one Phoronida) to obtain more comprehensive coverage of polychaete diversity for this gene. Analyses of the data do not resolve all inconsistencies among current hypotheses of polychaete phylogeny. They do support the recognition (in whole or part) of some clades such as the Eunicida, Phyllodocida and Terebellida that have been proposed on morphological grounds. Our analyses contradict the Canalipalpata and the Scolecida. Although the polychaete sister-group to the Clitellata is not clearly resolved in our analyses, the clitellates are always recovered as a derived clade within the Polychaeta. Increased taxon sampling is required to elucidate further the phylogeny of the Polychaeta.

A phylogenetic analysis of the polychaete clade Terebelliformia (Terebellida) was undertaken in order to test monophyly of families and subfamilies and to determine their affinities. Parsimony analyses of 41 terebelliform species with outgroup Owenia fusiformis and 46 morphological characters yielded 106–144 most parsimonious trees with length 250, consistency index=0·432, retention index=0·659 and rescaled consistency index=0·285. Monophyly was indicated for Alvinellidae, Ampharetidae, Terebellidae and Trichobranchidae and the terebellid subfamily Polycirrinae. Monophyly of Terebellidae is supported by the presence of a ridge-like tentacular membrane. Monophyly of Polycirrinae is supported by the loss of branchiae, trilobed upper lip, pinnate secondary notochaetae and ventro-lateral pads. Recognition of Polycirrinae renders taxa in the other terebellid subfamilies—Terebellinae and Thelepodinae—paraphyletic. Our results do not support previous classifications that placed Trichobranchidae as a subfamily of Terebellidae; rather it should be considered equal in rank with Alvinellidae, Ampharetidae, Terebellidae and Pectinariidae. The following relationships were obtained: (Trichobranchidae ((Alvinellidae, Ampharetidae) (Pectinariidae, Terebellidae))). This is the first time a Pectinariidae–Terebellidae sister group relationship has been found; it is supported by the synapomorphic presence of ventral glandular shields.

To assess the phylogenetic interrelationships of Trichobranchinae (Polychaeta: Terebellidae), we present the results of a cladistic analysis based on morphological characters coded as contingent. We also present an alternate way to number anterior segments, based on a reinterpretation of prostomial and peristomial morphologies in different genera. The ingroup terminals included 28 species, and the outgroup included one species of Ampharetidae and four species belonging to other subfamilies of Terebellidae. The monophyly of Trichobranchinae is clearly supported by the presence of long shafted uncini in thoracic neuropodia and by the absence of ventral shields. Species of Terebellides share lamellate branchiae, uncini with a long and narrow manubrium without denticles and uncini with a long and sharp main fang in the eighth segment. Species of Octobranchus share subquadrate branchiae on segments 3, 4 and 5, notopodia first present from segment 4, and uncini with a long shafted manubrium first present from segment 6. The autapormophy for Unobranchus is the presence of a single filiform branchia on segment 3. Artacamella falls into one of the Trichobranchus clades and is treated as a junior synonym of the latter.

The intraspecific variation in the number and distribution of paragnaths in ten populations of Nereis (Neanthes) virens collected throughout its range was examined. Significant differences among populations are found in the total number of paragnaths and in each paragnath group. The unweighted pair-group method using arithmetic averages cluster analysis revealed three distinct clusters separating Canadian populations, Europe/USA populations and the Japanese population, suggesting the implication of either restricted gene flow, selection on paragnath patterns or phenotypic plasticity. Comparison with a previous genetic study suggests that morphological variants represent ecotypes of the single, widely distributed N. virens species.

The growth of the Ficopomatus enigmaticus reefs was measured throughout a coastal lagoon at different temporal and spatial scales (over 24 years, annually and monthly throughout the coastal lagoon). The results show that reef cover increased in the last 24 years, and many neighbouring reefs have coalesced into large platforms. Growth rate varies spatially and temporally. Small reefs grow faster than large ones. Ficopomatus enigmaticus polychaetes living in higher salinity areas show a lower biomass than those living in brackish water areas, and the same pattern was observed for the inter-ring distance measured on the tubes. The results also show that important environmental variables, including salinity, nutrient availability and environmental energy (measured as current speed and depth) may be the most important factors affecting the growth and spread of the reefs.

A new species of sphaerodorid (Polychaeta: Sphaerodoridae), Sphaerodoropsisgarciaalvarezi sp. nov., is described from specimens collected on sandy bottoms off the Galician coast (Spain, north-east Atlantic). This species is characterized by having two pairs of digitiform lateral antennae, 13 dorsal macrotubercles per segment in mid-body setigers arranged in two transverse rows, five dorsal microtubercles per segment arranged in five longitudinal rows, six ventral papillae per segment arranged in six longitudinal rows, digitiform presetal lobes and ventral cirri, and composite setae with spinulation on blade and distal end of shaft. Complementary observations to original descriptions are also provided for closely related species Sphaerodoropsis bisphaeroserialis and Sphaerodoropsisarctowskyensis upon examination of type series.

Antropora commandorica sp. nov. is described from the Commander Islands (Bering Sea). This species is unique within the bryozoan genus Antropora in its sub-Arctic distribution; all other known species are distributed in tropical and sub-tropical waters. This species is also most often found as an epibiont of gastropod shells, some with an associated pagurid crab. Whilst this is not unknown in other species of the genus Antropora, A. commandorica appears to use these substrata almost exclusively.