The patterns of distribution, abundance and reproduction of the Indo-Pacific barnacle Balanus amphitrite were surveyed at Costa do Sol mangrove, Maputo Bay, southern Mozambique using stratified sampling design. Balanus amphitrite exhibited a spatial variation in which high numbers of individuals colonized the upper stratum in comparison to the lower stratum. Seasonal abundance of B. amphitrite was greater in the upper stratum and declined in June and September. In contrast, very high densities of individuals were recorded in winter in the lower stratum. Gonad cycle showed continuous trend and release of embryos mainly took place in winter (May–July). There was a strong quadratic effect of temperature on breeding activity of B. amphitrite, with females continuing to brood at lower temperatures. Egg numbers increased linearly with female size. The success of the reproductive activity may be synchronized within the species, enhancing the establishment and colonization of B. amphitrite in the study area.

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.

Previous studies on the ultrastructure of barnacle cypris larvae suggest that cypris morphology, especially the antennules which play a key role in selecting the final substratum for settlement, may show variations between species existing in different habitats. In the present study, the cypris morphology of the barnacle Fistulobalanus (Balanus) albicostatus, which predominantly lives on trunks of mangrove trees was investigated using scanning electron microscopy and compared with that of species from other habitats that have already been described. The antennular segments II and III of F. albicostatus each bear one post-axial seta. The third segment consists of an attachment disc surrounded by a thin cuticular velum and the fourth segment exhibits four sub-terminal setae and five terminal setae. The morphology of the cypris antennules of F. albicostatus is similar to other balanomorph barnacles which inhabit hard shores, revealing that the antennular morphology does not have diagnostic variations between species from the different intertidal habitats. The morphology of the caudal rami (used in the evaluation of the substratum microtopography), however, appears to vary among barnacles living on different substrata.

Deuterium oxide was used to measure isotope dilution space 11 times in seven free living, adult, male Atlantic walruses (Odobenus rosmarus rosmarus) (930–1597 kg) in north-east Greenland in the month of August 2000 and August 2001. Telemetry instruments, which were attached to the animals as part of a long term study, provided data on activity levels. Equilibration of the intravenously injected isotope was complete after 2–3 h. The application of a general correction factor developed for all pinniped species allowed the estimation of total body water content as 56.8% (range: 36.6–73.3%) of total body mass (TBM). Water turnover averaged 44.5 g kg-1 d-1. For one animal it was possible to estimate water influx to 4.8 g kg-1 d-1 and water efflux to 21.8 g kg-1 d-1. The estimates of body fat and body protein averaged respectively 24.7% and 18.4% of TBM. Similarly, for an ‘average’ walrus with a TBM of 1300 kg body ash was calculated to average 26 kg and body gross energy to 18,300 MJ. The assessment of body fat by isotope dilution did not differ significantly from the estimates of blubber content obtained from the dissection of walruses in the wild.

Early descriptions for species of Aka were poor in detail, and the only spicule type that occurs in this genus does not vary much between species, which led to taxonomic confusion. Moreover, the type specimens of five species of Aka are lost, causing considerable problems. Mediterranean specimens of Aka were identified as Aka labyrinthica (Hancock, 1849) by Topsent (1900), even though this species was originally described from the Indo-Pacific. All following publications on Mediterranean Aka accepted Topsent's decision. We assessed this problem with new samples from the Ionian Sea. Our material consisted of only one specimen of Aka, and we had to rely mainly on spicule characters for comparison with other species. We developed a system for species recognition solely based on spicular characters and biometry, involving a combination of the parameters oxea length, width, tip form and angle of curvature. This approach was surprisingly accurate. Forming ratios of the above parameters was less helpful, but can sometimes provide additional information. We identified our sample as Aka infesta (Johnson, 1899), and describe it as a minute-fistulate species with large, multicamerate erosion traces and stout, smooth oxeas. Our data further imply that A. labyrinthica sensu Hancock has not yet been found in the Mediterranean. Aka labyrinthica sensu Topsent is a collection of different species not including A. labyrinthica sensu Hancock.

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.

In this study we present results on epibionts on Zygochlamys patagonica from material collected during monitoring cruises in different areas in the Argentine Sea. We update the checklist of epibionts increasing the number of taxa from 19 to 41 and considering two species closely associated with the shells. The demosponge Iophon proximum was the most frequent and abundant epibiont (% presence and coverage). Polydora sp. was registered as a parasite of Z. patagonica in shells from the Beagle Channel, but it did not infest scallops from the commercial beds. Zygochlamys patagonica shells constitute conspicuous hard substrate available for the settlement of sessile organisms. This fact leads to an increased benthic richness in the continental soft-bottom areas of the Argentine Sea, where scallop beds are located.

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.

The present study describes the reproductive cycle and population structure of the intertidal crab Petrolisthes laevigatus, an abundant inhabitant of the upper rocky intertidal zone, as well as the relationship between seasonal patterns in the release of its planktonic larvae and recruiting. A total of 22900 individuals was collected along the coast of southern Chile between May 2001 and March 2003.The structure and density of the adult population (males and females) was relatively constant throughout the study period, although seasonal variations were observed in these two parameters of the benthic population (males, females, juveniles and megalopae), principally due to the incorporation of new individuals (recruitment) into the intertidal zone. Petrolisthes laevigatus presented a prolonged reproductive period. Females with initial eggs were present from the end of summer through to the middle of the following summer (11 months) and the breeding season lasted seven months (from August to February), as reflected in the six months of intertidal settlement (October–March).The interannual patterns and variations observed in the settlement along the southern Chilean coastline were related to the patterns in the abundance of potential released planktonic larvae. Petrolisthes laevigatus, unlike most temperate species, has a broad reproductive and settlement period in the south of Chile, which allows a highly stable structure and population abundance in this intertidal zone.

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.

The minke whale (Balaenoptera acutorostrata) is a widespread, opportunistic species showing spatial and seasonal variations in diet according to local availability of prey. Although previous research has been conducted on the foraging strategies of this small rorqual whale, in terms of prey aggregation and assimilation, relatively little has been published on the foraging association of this species with coastal seabirds. Over the past five years, minke whales occurring along the outer coastline of the southern Moray Firth in north-east Scotland during the summer and autumn months have been recorded foraging in the presence of seabirds, such as kittiwakes (Rissa tridactyla), herring gulls (Larus argentatus), guillemots (Uria aalge) and shearwaters, which form dense feeding rafts at the water's surface. The formation of bird rafts notably occurs independently of the presence of B. acutorostrata, believed instead to be the successive result of prey concentrated at the surface by predatory schooling fish from below rather than by activities of the whales themselves. In this area of the North Sea, schooling mackerel (Scomber scombrus) constitute the most significant component of the summer fish biomass and are believed to perform the role of compacting targeted sandeel (Ammodytes spp.) prey into concentrated bait balls almost exclusively. The resulting ball of prey is consequently available to the foraging whale, which can be seen opportunistically utilizing successive bird rafts rather than expending unnecessary energy corralling the Ammodytes prey by traditional, active entrapment methods. The role of the mackerel in increasing both the rate and density of sandeel ball formation (as indicated by the presence and activity of associated bird rafts) is therefore thought to be very significant in this inshore Scottish location. Changes in oceanographic variables such as water temperature have been directly correlated with the migration of S. scombrus. The observed inter-annual variability in B. acutorostrata distribution in the outer Moray Firth may subsequently be related to the respective distribution and abundance of these migratory, pelagic fish species.

This paper focuses on Aka species boring coral of the East Pacific Ocean and the Caribbean Sea (Mexico). The new species Aka cryptica sp. nov. is described from Mexican Pacific coral reefs, which constitutes the first time that a species of the genus Aka is reported from the East Pacific Ocean. The new species lives cryptically boring coral species of the genus Pocillopora. It is characterized by the small size of their papillae (from 1 to 4.5 mm high and from 0.8 to 1.8 mm in diameter), and oxeas (from 67 to 120 μm), and their exposed parts blend in well with background colours which tend to be overlooked during benthic marine surveys. In addition, Aka coralliphaga and Aka brevitubulata from Mexican Caribbean coral reefs are redescribed. The latter species is reported for the first time in Mexico.

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.

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.

Phorbas is a common genus with cosmopolitan distribution. A new species of sponge, Phorbas megasigma sp. nov. (Porifera: Poecilosclerida: Hymedesmiidae) is described from material collected during the third Spanish expedition on the study of the Antarctic benthos, ‘Bentart 03’. Phorbas megasigma is closely related to P. nexus but differs in the possession of arcuate chelae and very big sigmata as microscleres.

To characterize temporal patterns of humpback group structure around Abrolhos Archipelago, Brazil, seven years (1998–2004) of data obtained from July through November were analysed. During one-hour scans, observers determined group composition within 9.3 km around a land-based station. A total of 930 scans, comprising 4288 groups were analysed. Seven group categories were identified and their frequencies were 14.6% of 1AD (lone whale), 25.2% of DYAD (two adult whales), 7.3% of TRIO (three adult whales), 5.2 of TRIO+ (more than three adults), 24.9% of MOC (mother and calf), 19.6% of MOCE (mother, calf and one escort), and 3.1% of MOCE+ (mother, calf and more than one escort). Proportions of whale-group categories did not change between morning and afternoon, nor among years. However, as the season progressed, groups with calves increased while groups without calves decreased. This progression may be explained by the segregated migration patterns of humpback whales and also by changes in the social status of individuals. The Abrolhos Reef provides protection from the prevailing winds, which may explain the higher proportion of groups with calves in the area.

The aim of this study is to analyse the co-occurrence of the encrusting sponge Iophon proximum and other sessile organisms on the shells of the Patagonian scallop, Psychrochlamys patagonica, and the relationship between scallop size and the presence of this sponge. Scallops were collected from four beds distributed along the 100-m depth isobath on the continental shelf off Argentina (south-western Atlantic). Statistically significant avoidance was observed between I. proximum and all other groups of sessile invertebrates. Co-occurrence of bryozoans, foraminiferans, folliculinid ciliates, hydrozoans, octocorals and spirorbid, serpulid and sabellarid polychaetes on valves not monopolized by I. proximum produced significant clumping, which, however, almost ceased to occur when only valves without this sponge were analysed. In Patagonian beds, valves monopolized by I. proximum were significantly smaller than those in which the sponge was absent (valve height, mean ±SE, with I. proximum: 54.1 ±1.74 mm, without I. proximum: 60.4 ±0.62 mm). This is the first study to report a significantly smaller size in sponge-covered scallops compared to those without sponges.

Waves breaking on rocky shorelines impart large forces on intertidal organisms, sometimes dislodging individuals. Dislodged individuals may be deposited in habitats that have a greater risk of predation or that prevent return to preferred regions on the shore. Thus, dislodgement is often assumed to be lethal. We experimentally dislodged Littorina keenae snails from high in the intertidal zone to test the likelihood of survival. Under a variety of wave conditions, we measured return rates to the high shore of 54–90%, so in this species, dislodgement is not equal to death. Snails showed a strong preference for returning to the approximate tidal height from which they were dislodged, but we found no evidence of widespread homing behaviour back to the original site of dislodgement.

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.

The main functional characteristics of haemocytes from the common periwinkle Littorina littorea (phagocytic ability, acid phosphatase activity, cytotoxic properties and generation of reactive oxygen intermediates) were investigated. The blood cells of L. littorea demonstrated phagocytic activity for zymozan particles in both plasma and seawater. However, the level of phagocytosis in plasma was higher than in seawater, suggesting the presence of some soluble factors with opsonizing activity for yeast cell walls in the snail haemolymph. Acid phosphatase was detected in haemocytes following phagocytosis of zymosan. Zymosan particles as well as soluble inducers of respiratory burst (mannan, phorbol-myristate acetate, lipopolysaccharide from Escherichia coli) were shown to trigger superoxide anion production in L. littorea blood cells as evidenced by nitroblue tetrazolium (NBT) reduction. Haemocytes exposed simultaneously to both inducer and the superoxide scavenger enzyme—superoxide dismutase demonstrated a lower ability to reduce nitrobluetetrazolium. Periwinkle blood cells showed plasma-independent cytotoxic activity for human erythrocytes which may be due to the release of superoxide intermediates into the extracellular environment. These results, together with previously obtained data, suggest that haemocytes are the main effectors in the internal defence system of L. littorea, with humoral factors playing an accessory role in recognition and elimination of pathogens.