The Aleutian margin is a dynamic environment underlying a productive coastal ocean and subject to frequent tectonic disturbance. In July 2004, we used over 500 individual bottom images from towed camera transects to investigate patterns of epibenthic megafaunal density and community composition on the contiguous Aleutian margin (53°N 163°W) at depths of 2000 m, 3200 m and 4200 m. We also examined the influence of vertical isolation on the megafaunal assemblage across a topographic rise at 3200 m, located 30 km from the main margin and elevated 800 m above the surrounding seafloor. In comparison to previous reports from bathyal and abyssal depths, megafaunal densities along the Aleutian margin were remarkably high, averaging 5.38±0.43 (mean±1 standard error), 0.32±0.02 to 0.43±0.03 and 0.27±0.01 individuals m−2 at 2000 m, 3200 m and 4200 m, respectively. Diversity at 2000 m was elevated by 15–30% over the deeper sites (3200–4200 m) depending on the metric, while evenness was depressed by ~10%. Levels of richness and evenness were similar among the three deeper sites. Echinoderms were the most abundant phylum at each depth; ophiuroids accounted for 89% of individuals in photographs at 2000 m, echinoids were dominant at 3200 m (39%), and holothurians dominated at 4200 m (47%). We observed a 26% reduction in megafaunal density across the summit of the topographic rise relative to that documented on the continental slope at the same depth. However, the two communities at 3200 m were very similar in composition. Together, these data support the modified ‘archibenthal zone of transition’ framework for slope community patterns with distinct communities along the middle and lower slope (the upper slope was not evaluated here). This study fills a geographical gap by providing baseline information for a relatively pristine, high-latitude, deep-sea benthic ecosystem. As pressures grow for drilling, fishing and mining on high-latitude margins, such data can serve as a reference point for much-needed studies on the ecology, long-term dynamics, and anthropogenically induced change of these habitats.

The spatial variation in abundance and composition of subtidal meiobenthos communities was studied in two Portuguese estuaries under distinct degrees of anthropogenic pressure. Samples were collected from 20 sampling stations along both estuarine gradients from freshwater (<0.5) to euhaline areas (>30). Of these stations 11 were located in the Mondego estuary, a system exposed to high anthropogenic stress, and 9 in the Mira estuary, a naturally stressed system located inside the Natural Park ‘Costa Vicentina’ (south-western coast of Portugal).

Total meiobenthos density was higher in the Mira estuary and in both estuaries the community was dominated by nematodes. Among the twelve taxa identified in the Mira estuary, Harpacticoid copepods and Polychaeta were the second and the third most abundant groups respectively. In the Mondego estuary, Polychaeta was the second while Harpacticoid copepods was the third most abundant group in the thirteen total taxa recorded.

Estuarine gradients of salinity, particles size and water nutrients were clearly detected in both estuaries and there was significant spatial heterogeneity in abundance and composition of the subtidal meiobenthos communities along these environmental gradients. Accordingly, three distinct sections were identified in both estuaries: (i) freshwater sections, where total density, and density of nematodes and Harpacticoid copepods reached minimum values; (ii) oligohaline and mesohaline sections, where the total density was low and diversity was poor; and (iii) polyhaline and euhaline sections, where both total density and diversity reached the highest values.

The similar spatial distribution of meiobenthos assemblages in both estuaries suggests that natural stressors may be the major factors controlling the physicochemical conditions that determine meiobenthos community patterns. The mesoscale variability of subtidal meiobenthos density and composition within estuaries (in the order of kilometres) seems to be more important than the variability between estuaries (at the scale of hundreds of kilometres), a common feature in intertidal systems. From the management point of view, these results, based on higher taxa resolution, represent an obvious constraint to the applicability of ecological quality evaluation tools.

Predation has long been recognized as an important biological force driving community patterns in intertidal rocky shores throughout the world. Little is known, however, about the role of predation by mobile marine predators in shaping intertidal prey populations in Portuguese rocky shores. The abundance and population structure of crabs were assessed during nocturnal low-tides on two rocky shores to characterize potential predator species. To assess the effect of predation on intertidal species including limpets, barnacles and mussels, predator exclusion experiments using full cage, partial cage and no cage treatments, were set up for two months on two shores on the central Portuguese coast. Pachygrapsus marmoratus (Fabricius) and Eriphia verrucosa (Forsskål) were the most abundant crabs. Results from predator exclusion experiments suggested that predators do not exert a significant control on abundance of limpets, mussels or barnacles on the midshore during the experimental period. Despite the fact that these crabs are known to feed on the analysed prey, several factors may account for the observed absence of impact on prey abundance and these are discussed.

Interannual variability of the primary production in the middle Adriatic Sea for the period 1961–2002 was examined and correlated to the various atmospheric and oceanographic parameters. The sequential t-test analysis of regime shift (STARS) method and locally-weighted scatter plot smoothing (LOWESS) method were applied to the primary production, revealing the new regime with significantly different mean productivity ranging from 1980–1996. Moreover, this period with the highest primary production, consists of the two distinguished sub-periods: periods of increasing (1980–1986) and decreasing (1987–1996) primary production. Whereas in the first period the ecosystem was under the influence of warmer and nutrient richer Levantine Intermediate Water (LIW) intrusions into the Adriatic, in the second period, which started with a cold winter in 1987, the Eastern Mediterranean Transient (EMT) occurred. The EMT established a new circulation regime which prevented the LIW intrusions in the Adriatic, causing its reduced productivity. Reduced LIW inflow in the Adriatic was evidenced in the lower than normal sea temperature, salinity and oxygen concentrations below the thermocline depth. Precipitation and wind regime also arose as important local factors for the primary production variability. Our analysis connected the shifts in primary production with hemispheric and regional scale climate variations, and supports the hypothesis that atmospheric variability can trigger the ecosystem changes.

The spatial and temporal variations of the microphytoplankton communities were examined during four oceanographic cruises conducted between July 2005 and March 2007 aboard the RV ‘Hannibal’. Water thermal stratification started in May–June, and a thermocline established at 20 m depth, but ranged between 25 m during July and more than 30 m during September. The high concentrations of chlorophyll-a were observed during the May–June semi-mixed conditions and were mainly correlated with the concentrations of phosphate, suggesting a potential limitation by this nutrient. The Bacillariophyceae were dominant in the coastal samples, whereas they declined in the offshore area, most likely due to silicate shortage. Cyanobacteriae developed over semi-mixed conditions and at the thermocline depth. Relatively constant abundance of dinoflagellates was observed during the sampling periods from the coast to the offshore area, mainly explained by the high diversity species of this group. The results suggest that some phytoplankton taxa are generally adapted to specific hydrological conditions, whereas the dinoflagellates did not seem to follow this trend. Our findings have important biogeochemical implications in relationship with the export fluxes of the particulate matter throughout the water column.

Biological invasions can alter the biodiversity of native communities generating an ecological impact that in many cases is irreversible. In 2001, Undaria pinnatifida invaded Macrocystis pyrifera kelp in Cracker Bay (42°56′S, 64°27′W; Northern Patagonia, Argentina). The possible impact of that invasion was evaluated in March 2004 with a study of population and morphological parameters of both kelp species and their associated holdfast biodiversity. Three nearby areas of spatial distribution of the kelps were differentiated, one dominated by M. pyrifera (M), an intermediate area characterized by M. pyrifera and U. pinnatifida (M+U), and another dominated by U. pinnatifida (U). In each area, sporophytes in nine quadrats of 1 m2 were collected. The density and biomass m−2, the height of the sporophytes and the size of the holdfast of  M. pyrifera did not diminish in the presence of  U. pinnatifida. The richness, abundance and diversity of the flora associated with the holdfast of both kelps were similar, whereas these parameters were higher in the case of the fauna associated to M. pyrifera than U. pinnatifida Results obtained in this work suggest that, at this invasion stage, there is no evidence of interspecific competition. Nevertheless, since density and diversity of the fauna associated with the holdfast is different, we expect community changes if the U. pinnatifida invasion continues to expand.

The spatio-temporal distribution of the soft bottom dwelling shrimp Nematopalaemon schmitti and the effect of environmental conditions (sediment characteristics, temperature, salinity and dissolved oxygen) on its abundance were studied at Ubatuba Bay, south-eastern coast of Brazil. Surveys were conducted monthly from September 1995 to August 1996. Each sampling set comprised eight different transects distributed within the bay. Comparisons of CPUE of shrimp among sampling stations demonstrated that the abundance of N. schmitti was the greatest during winter, when average water temperature within the bay was considerably lower than during the rest of the year. Most shrimps (more than 95%) were collected at a single transect located at the northernmost side of the bay, demonstrating the extremely patchy distribution of this species. A multiple regression analysis using data only from this northernmost transect indicated that temperature was the most relevant factor affecting the abundance of N. schmitti during the year.

The identification of key resource users and patterns of depletion alongside ecological data are presented for a small-scale traditional invertebrate fishery in south-western Madagascar. Men, women and children undertake the fishery in the Anakao region at different phases of the tide and for different purposes. Invertebrate harvest data from June to September 2000 estimated that more than 34 taxa were caught and were dominated by holothurians destined for export and molluscs for local consumption. Crustacea formed a small component of the fishery despite a high diversity and abundance of many potentially edible species. Although there was slight spatial variation in number of species caught and their relative importance to the fishery, Chicoreus ramosus, Fasciolaria trapezium and Octopus vulgaris were generally most heavily targeted and were amongst the most abundant in the catch. There were several indications of over-exploitation of invertebrate stocks, including the absence of many large bodied species, low abundance of high yield species, greater catch effort needed for high yield taxa, and higher diversity of targeted species (including many low yield taxa) at sites of higher human habitation.

Distribution of fur seals Arctocephalus australis has been studied in October 2007 on the western, southern and eastern Falkland shelves during the survey of spawning grounds of the red cod, Salilota australis. Fur seals presence/absence, numbers and sex were recorded at every oceanographic station. Animals were found foraging on the shelf edge south-west of the islands, in a productive zone with quasi-stationary eddies at a periphery of upwelling. It was also the zone of maximum abundance of lobster-krill, Munida spp.—an important food source of fur seals and aggregations of both red cod and blue whiting, Micromesistius australis. No fur seals were found in waters of the relative cold and saline Falkland Current as well as in the relatively warm, fresh and oxygen-rich waters of Argentine Drift. It allows supposing that position and extension of the foraging grounds are caused by oceanographic features determining distribution of prey species.

Biometric relationships were recorded for 2431 male and female Panulirus echinatus sampled at Tamandaré coastal reefs, Pernambuco, Brazil. The following body measurements were taken: carapace length and width, abdomen length and width, total length, third and fifth pereiopod length, cephalothorax–abdomen and total weight. Twelve relationships were studied to compare the biometric characteristics of males and females. Eleven of them showed difference between the sexes. Comparing sexes with the same carapace length, males have a heavier cephalothorax and longer third and fifth pereiopods than females, whereas females are longer, wider, and have a heavier abdomen than males. For genders with the same total length, males are heavier and have a longer carapace than females, while females have a larger abdomen. For genders with the same abdomen length, males have a heavier abdomen than females. The relationships TWg/TL and AWg/AL showed positive allometric growth for the males. All other relationships involving weight, presented negative allometric growth for both sexes.

The larval and post-larval behaviour, growth, colour, and morphology of the brown box crab (Lopholithodes foraminatus) are described for the first time based on laboratory reared animals. A detailed morphological description is provided for 4 zoeal stages, the glaucothoe, and the first crab instar. Selected morphological changes over the remainder of the first year of development are also described. Data are presented on larval growth at 11°C and on zoeal stage durations at approximately 8°C, 12°C and 16°C. While the 4 zoeal stages are planktotrophic, the glaucothoe does not feed; a life history character that has been termed ‘secondary lecithotrophy’. Growth of L. foraminatus larvae and post-larvae is generally similar to that of other North Pacific lithodids with planktotrophic zoeae. Zoeal stage durations decrease with increasing temperature. This relationship levels off at approximately 16°C, a higher temperature than in lithodid species from colder regions. Carapace morphology is suggested as a diagnostic character of larval and post-larval stages of Lopholithodes foraminatus. Secondary lecithotrophy may be widespread or even universal among lithodids and also occurs in pagurid hermit crabs. If the family Lithodidae is indeed nested within the Paguridae, as suggested by recent phylogenetic hypotheses based on molecular evidence, secondary lecithotrophy may be plesiomorphic in lithodids.

Size-at-maturity, often used by fisheries managers to specify reference points, was estimated for Cancer edwardsii, the most intensely exploited brachyuran crab in Chile, using morphometric data and observation of the gonadal cycle. Sampling was conducted in Chiloé Island, the principal landing region. Several morphometric measurements of secondary sexual characters were recorded for both sexes. Their size-dependence was investigated in search of ontogenetic allometric changes. Six stages of maturity were established for females, and four for males, on the basis of macroscopic and histological observation of the reproductive system, allowing distinction between adults and juveniles. Females and males, on average, attained full development of secondary sexual characters at 106 and 118 mm carapace width (CW) respectively. The CW at which 50% of females and males have gonads of adult appearance was around 101 mm. Current minimum legal size is 120 mm CW, seemingly high enough for conservation purposes. This management control, however, is unlikely to provide effective protection due to the high proportion of crab of sub-legal size in the landings. Traps with escape vents could be introduced in this fishery in order to ensure its sustainability.

Solen dactylus is a razor clam distributed throughout the coast of the northern Persian Gulf. Study on biology of razor clams in this area is important for an essential management where these clams are overfished without any control. This study provides the first estimate of growth rate and an interpretation of the reproductive cycle of S. dactylus on the coast of the Persian Gulf (Bandar Abbas). In this study, 945 razor clams were collected from April 2007 to March 2008 along two transects of Golshahr coast in Bandar Abbas. Von Bertalanffy growth parameters for transects 1 and 2 ranged from 101–108 mm for asymptotic length (L∞), 0.27–0.28 year−1 for growth constant (k), and −0.99–0.94 for age at length zero (t0), respectively. Gonads were stained with haematoxylin and eosin and gametogenic stages were based on seven stages: (Stage 0) sexual rest; (Stage I) proliferation of gonad and start of gametogenesis; (Stage II) advanced gametogenesis; (Stage IIIA) ripeness; (Stage IIIB) start of spawning; (Stage IIIC) restoration; and (Stage IV) emission. The result showed that S. dactylus is a gonochoric clam and both males and females demonstrated synchronism in gonadal development. The gametogenic cycle began in late August and ended in late February. After several minor spawnings, plus a major one in January, the razor clams entered to the sexual rest stage in March.

Research vessel survey data collected by Fisheries and Oceans Canada in the southern Gulf of St Lawrence (1971–2002) and Cabot Strait (1994–1997) were analysed to determine if Enchelyopus cimbrius the fourbeard rockling, distributed itself with larger individuals occurring in deeper water. A positive size–depth relationship was first observed for the European plaice, Pleuronectes platessa in the North Sea and has been reported for other fish. Positive relationships were found between the total length of E. cimbrius and depths where it occurred in this study. However, the biological relationship was not significant since the linear regression slopes were very weak, explaining less than approximately five per cent of the variance observed. Data were analysed further to determine the water depth, temperature and salinity ranges where the fourbeard rockling was most abundant. Enchelyopus cimbrius occurred throughout the depth-ranges sampled with highest catches occurring at 25–50 m (southern Gulf of St Lawrence) and deeper than 200 m (southern Gulf of St Lawrence and Cabot Strait). Low catches at intermediate depths (~50–100 m) in the southern Gulf of St Lawrence may have been due to the lack of suitable mud substrate and colder bottom temperatures in the Magdalen Shallows, a large central region of the southern Gulf. Enchelyopus cimbrius was mostly caught at relatively narrow temperature and salinity ranges of 4–6°C and 34–34.9 ppt in both regions, and only occurred in areas with a mud substratum, predominantly in the eastern Northumberland Strait, Baie des Chaleurs and in the deeper water of the Cape Breton Trough, Laurentian Channel and Cabot Strait. Enchelyopus cimbrius was caught throughout the day and night, contradicting a previous study that characterized it as being nocturnal in shallow coastal waters off Newfoundland.

The banded guitarfish, Zapteryx exasperata, is a common species in the artisanal elasmobranch fisheries in the Gulf of California. Fishery-derived specimens were examined to determine critical aspects of the reproductive biology of this poorly known group of rays. Two functional testes and ovaries were found in males and females respectively. Median size at maturity (L50%) for males was 64 cm total length (TL) and for females 69 cm TL. Average length of gravid females was 78.8±3.8 cm TL. Histological analysis showed no evidence of sperm storage in the oviducal gland. Gestation was estimated to occur over a five to six month period (February–July) and was concurrent with vitellogenesis. Mean uterine fecundity was estimated as 7 (range 2–13, SD. = 3). The sex-ratio of embryos was 1:1. The reproductive cycle for Z. exasperata from the Gulf of California was estimated to last one year with parturition, ovulation and copulation occurring during the summer months. Differences found in the reproductive cycle of Z. exasperata between the Gulf of California and the west coast of Baja California could have implications in the future management plans for this fishery in the Gulf of California.

A new species of Leucosoleniidae, Leucosolenia microspinata sp. nov., from the southern Tyrrhenian Sea (Porto Vecchio pond, Marinello Marine Reserve, Messina) is here described. The species consists of a dense reticulation of ascon tubes having a colour ranging from white-cream to light-brown. Its spiculation consists of diactines sometimes serrated or microspined, not separable into size-classes, triactines of four types and tetractines with microspined apical actine. The comparison with other Mediterranean Leucosolenia is reported.

Two new species of Poecilosclerida Crella (Crella) aurantiaca sp. nov. (Crellidae) and Mycale (Aegogropila) denticulata sp. nov. (Mycalidae) are described on the basis of material collected during the XX Italian Expedition (2004–2005) in Antarctica. Crella (Crella) aurantiaca sp. nov. is based on presence of acanthostyles of two size-categories. Mycale (Aegogropila) denticulata sp. nov. is characterized by the presence of palmate anisochelae and styles.

Cymbastela sodwaniensis sp. nov. (order Halichondrida: family Axinellidae) is described from the subtropical waters of Sodwana Bay on the north-east coast of South Africa. The genus was previously unknown from southern Africa or the western and eastern parts of the Indian Ocean. This record represents the westernmost extent of this predominantly Indo-Pacific to Australasian genus. This new species record brings the number of Cymbastela species described to a total of nine.

The sponge genus Strongylodesma is reviewed and redefined, and now accommodates eight closely related species. The type species of Strongylodesma Lévi is redescribed and an additional two new species are described from the Indo-Pacific: S. novaecaledoniae sp. nov. and S. tongaensis sp. nov. Several specimens previously identified as species of Batzella (Poecilosclerida: Chondropsidae) have been re-assigned to Strongylodesma, as the new species S. purpureus sp. nov. and S. nigra sp. nov. With the description here of new species from the Pacific Ocean and Caribbean Atlantic, the biogeographical distribution of Strongylodesma now appears to be generally tropical with a subtropical South African component, whereas previously it was only known from South Africa. Although species of Strongylodesma have not previously been recorded from the intermediate locations (Western Indian Ocean, South-east Asia, central west Pacific, and New Zealand), re-evaluation here will facilitate more readily the recognition of taxa in these intermediate regions, if they exist, in the future. The species are not widespread, except perhaps along the south-east coast of South Africa, and where they occur they are not abundant. Species occur over a wide depth range, from the intertidal in Tsitsikamma, South Africa, to 140 m in the Caribbean.

The aim of this study was to characterize new microsatellite loci in the razor clam Ensis arcuatus (Bivalvia: Pharidae) and examine the temporal genetic variability of a natural bed in Cies Islands (Galicia, north-western Spain) exploited by apnoea divers and affected by the ‘Prestige’ oil tanker spill in November 2002. In this work, we characterized four polymorphic microsatellites using an alternative approach that relies on the amplification and sequencing of ISSR markers. Observed heterozygosities ranged from 0.1053–0.6800 and number of alleles from 4–19. Linkage equilibrium was observed in all loci and two of them showed significant deviations from Hardy–Weinberg equilibrium. Estimators of FST between samples were low (<0.05) and not different from zero with a confidence level of 5%. We did not detect a clear decreasing tendency in genetic diversity although we found a significant change in allelic frequencies among samples (P = 0.0024) after the ‘Prestige’ oil spill. We propose that both phenomena could be related to a high variance in genetic success and/or a movement of adults or larvae from different source populations.