It is widely assumed that optimal timing of larval release is of major importance to offspring survival, but the extent to which environmental factors entrain synchronous reproductive rhythms in natural populations is not well known. We sampled the broods of ovigerous females of the common shore crab Pachygrapsus transversus at both sheltered and exposed rocky shores interspersed along a 50-km coastline, during four different periods, to better assess inter-population differences of larval release timing and to test for the effect of wave action. Shore-specific patterns were consistent through time. Maximum release fell within 1 day around syzygies on all shores, which matched dates of maximum tidal amplitude. Within this very narrow range, populations at exposed shores anticipated hatching compared to those at sheltered areas, possibly due to mechanical stimulation by wave action. Average departures from syzygial release ranged consistently among shores from 2.4 to 3.3 days, but in this case we found no evidence for the effect of wave exposure. Therefore, processes varying at the scale of a few kilometres affect the precision of semilunar timing and may produce differences in the survival of recently hatched larvae. Understanding the underlying mechanisms causing departures from presumed optimal release timing is thus important for a more comprehensive evaluation of reproductive success of invertebrate populations.

The temporal and spatial variability in population dynamics of the European crab Carcinus maenas (L.) was studied between June 2003 and September 2007 in the Mondego estuary. An extreme climate event (extreme drought) occurred in 2004 and 2005 with a low freshwater flow discharge into the estuary, leading to an increase in salinity. Juveniles' recruitment was continuous throughout each year with a high proportion of young recruits being recorded in the spring of 2005. The proportion of green crabs clearly increased from the mouth to the upstream areas and the proportion of crabs actually in moult followed the same pattern. Parasitization by the endoparasitic barnacle, Sacculina carcini was observed, principally at the mouth of the estuary. The C. maenas population showed a regular size–frequency distribution and structure for both sexes during the study. Secondary production (P) of C. maenas estimated for the 4-year study period was different between years though, P/B ratios were similar during the whole study period. During the drought period, catches of the crab recruits were higher, particularly in the spring, probably due to the increase in salinity, which emphasizes the importance of these extreme events in controlling the abundances of coastal populations.

The relative growth and population structure of the terebellid Nicolea uspiana were investigated in the intertidal zone of a rocky shore on the south-east coast of Brazil, from May 2006 to May 2007. Eight hundred and forty-seven individuals of N. uspiana were analysed: 391 males, 163 females, and 293 immatures. Although significant differences in some morphometric parameters were found, there was no sexual dimorphism between males and females. There were differences in total length, width of segment 5, and length of the notopodial region between matures and immatures. The negative allometry of the total length in relation to five other parameters showed that this feature is a good measure for estimating the individual size, which was then used in the analysis of population structure. This population of N. uspiana showed a bimodal size–frequency distribution, with immature and mature individuals found during the entire year. This pattern indicates continuous reproduction, with each cohort growing for at least three to four months and being responsible for two consecutive settlement peaks.

Pinna nobilis is an endemic bivalve of the Mediterranean Sea. In the last decades P. nobilis populations have declined drastically due to increasing anthropogenic pressure and it has been declared a protected species since 1992. Despite the need for conservation, knowledge of the ecology and monitoring of the main populations of P. nobilis are limited. This study considered a population living within a Posidonia oceanica meadow in the Gulf of Oristano (western Mediterranean, Italy). The study area, about 150 hectares, part of which is included within a Marine Protected Area and a Site of Community Importance, was subdivided in 3 sub-areas. The percentage cover of different habitat types (P. oceanica, dead matte and sand) in each sub-area was measured and meadow features (substrate coverage, matte compactness and shoot density) characterized. The hypotheses of differences in density, percentage of dead individuals, population structure, shell burial level and orientation of P. nobilis, were investigated according to sub-areas and to habitat type. The spatial distribution was patchy, and the habitat type resulted a key factor in determining both density and distribution. A strong edge effect was demonstrated: more than half of the observed individuals colonized the P. oceanica border. Matte compactness and shoot density were found to affect the density and distribution of P. nobilis. Shell burial level and percentage of dead individuals varied with sub-areas and habitat types. Size distribution was bimodal and common shell orientation was observed in two sub-areas. These results contribute to increase the knowledge of population ecology of this species and to provide useful information for implementing conservation policies.

The Atlanto-Mediterranean holothurian Holothuria tubulosa is among the conspicuous benthic invertebrates in the shallow sublittoral zone. It is an edible species, harvested at the Aegean Sea and utilized as fishing bait. Considering the lack of information for the Aegean populations, a one-year survey, based on monthly or semimonthly samples, was carried out focusing on population structure, allometric relationships and reproductive status of H. tubulosa stocks in Pagasitikos Gulf. Population density varied around 9.93 individuals/100 m2. This value was rather low compared with other studied Mediterranean populations of the species, possibly due to the scarcity of seagrass meadows in the area studied. All measured biometric characters showed high plasticity, and all the examined morphometric relationships followed negative allometry indicating a change to the shape of the animal's body as it grows. Holothurians’ length was a moderate predictor of biomass since r values reached 60%; in contrast a very strong relation was observed between drained and gutted weight. Size–frequency distribution analysis was unimodal with the exception of spring where a second mode of larger sized individuals appeared. The gonadosomatic index showed a single spawning season per year, in late summer; accordingly the reproductive cycle of the species showed a clear annual pattern which was highly correlated with the seasonal variations of temperature.

Ecological information on the polychaete community may improve habitat descriptions and distribution models of commercially important species that are polychaete-feeders. This study reports on the first new observations in nearly three decades on the polychaete assemblages in the south-eastern Bering Sea. This information was used in an exploratory assessment of the association between polychaete assemblages and environmental variables that define the benthic habitat. The spatial association between polychaete assemblages and groundfish predators was also explored for insight into whether prey assemblages influence predator distribution. Canonical correspondence analysis indicates that surficial sediment is the most important factor in organizing polychaete assemblages, over other common environmental variables such as depth and temperature. Co-correspondence analysis of the distributions of groundfish species and polychaete families does not indicate that predators are associated with specific prey families. Families that are most frequent in stomach contents of some of the fish in the analysis, mainly Maldanidae and Nephtyidae, are widely distributed across the Bering Sea shelf in diverse sediment types, as are the principal polychaete-feeders in the eastern Bering Sea such as Alaska plaice (Pleuronectes quadrituberculatus) and northern rock sole (Lepidopsetta polyxystra).

In 1998, in coincidence with high sea surface temperatures, Maldivian reef corals were severely affected by mass mortality following bleaching. Tabular Acropora corals, formerly abundant in shallow water, were nearly exterminated. Recovery started soon, and in 2004 Maldivian reefs appeared rich in tabular Acropora colonies again, especially at some sites. This study aimed at determining the degree of spatial variability of tabular Acropora abundance and size among reef typologies (ocean versus lagoon reefs) and depth zones (4–6, 10–12 and 16–18 m) 6 years after the mass mortality event. A total of 192 tabular Acropora colonies (Ø > 16 cm) were counted and measured in six sites. Their abundance differed between reef typologies and according to depth zones, with the highest values in deep lagoon reefs. Colony mean size differed only among depth zones, the largest colonies (up to 105 cm) being found in shallow reefs. Assuming a radial extension rate of 10 cm · yr−1, colonies larger than 65 cm can be interpreted as the survivors of the mass mortality of 1998; conversely, they may represent the result of enhanced growth rates in uncrowded situations as those characterizing the coral reefs of the Maldives in 2004.

Benthic polychaetes in the largest intertidal mudflat of Hong Kong were analysed for potentially stressed environmental conditions from pollution. Over a two-year period, a total of 14 species were recorded with the species diversity (H′(log2)) ranged from 0.54 to 2.4. The community was dominated by two large polychaetes (Neanthes glandicincta and Potamilla acuminata) and a number of small pollution tolerant species (Tharyx, Capitella capitata and Prionospio cirrifera). It was also characterized by both temporal and spatial variations in terms of abundance and species composition with the lowest species number observed at onshore Station B in August and the highest at offshore Station D in February. Two distinct polychaete communities were formed along the intertidal towards subtidal mudflat, particularly the assemblage at onshore Station B showing a significant difference from those at the other three stations (P < 0.05, N = 32). Results of the abundance–biomass comparison (ABC) indicated a typical impacted community at the whole study area, especially at Station B which was close to the Shenzhen River mouth and mangrove forest. The total organic carbon had a significant positive effect on the abundance of Capitella capitata (P = 0.037, N = 8) while sedimentary compositions were statistically related to the abundance of Potamilla acuminata, Tharyx and total abundance of polychaetes (P < 0.05, N = 8). In conclusion, both the polluted Shenzhen River and nearby mangrove may be responsible for the decline in species richness and diversity as well as changes in community structure. Polychaetes can be used as the appropriate indicators in habitat ecological condition assessment instead of the whole benthic community.

The aim of this study is to characterize the different macrozoobenthos communities in Mar del Plata waters (south-western Atlantic) on the basis of their abundance and habitat, and to determine how sediment characteristics, like the grain-size composition, affect macrobenthic community structure. Multivariate techniques indicated that benthic communities and sediments in the surveyed area were included into the following five well-defined groups: (1) a medium sand assemblage dominated by the bivalve Crassinella marplatensis and Diplodonta patagonica, the echinoderm Encope emarginata, the tanaidacean Bacescapseudes sp. and the polychaete Armandia loboi; (2) a medium to very fine sand assemblage dominated by ostracods, the tanaidacean Bacescapseudes sp., amphipods and polychaetes of the family Nephtyidae; (3) a fine to very fine sand assemblage dominated by the tanaidacean Bacescapseudes sp.; (4) a silt and fine sand assemblage dominated by polychaetes particularly Scolelepis sp. and individuals of the family Nephtyidae; and (5) a fine sand assemblage dominated by amphipods and the tanaidacean Bacescapseudes sp. These results revealed the patchy distribution of macrobenthic assemblages as a result of sediment characteristics and serve as baseline information for this area strongly subjected to trawling perturbations.

Settlement of the fouling community is generally influenced by the physical, chemical and biological properties of the settling surface. The colour of the substratum may also exert an influence on larval settlement. In the present study, the influence of surface colour on the recruitment of fouling communities was investigated by suspending acrylic panels (red, green, blue, white and yellow) in coastal waters. Results showed that the colour of the substratum plays an important role in the recruitment of sessile species. Recruitment was comparatively high on red and blue coloured surfaces. Barnacle and tubeworm recruitment showed significant variation (Tukey test, P < 0.05) between different coloured surfaces. The significant conclusion of this study is that the colour of the artificial substrata should be taken into consideration when interpreting results from short-term biofouling studies.

The burrow morphology of the mud shrimp Upogebia yokoyai was investigated on a tidal flat in the Nanakita River mouth in north-eastern Japan using in situ resin casting. A total of 26 burrow casts were recovered, including those of 16 large shrimps and 10 small shrimps. Burrows of large shrimp were relatively simple and Y-shaped with depth exceeding 1.2 m. Although burrow diameter was related to shrimp size, correlation with other burrow measurements was low. Three large casts were connected to others via a narrow horizontal portion potentially reflecting mating behaviour of the shrimp. Burrows of small shrimp were more complex than those of the other upogebiids and were connected to large burrows. In 6.7% of cases, bopyrid isopods were present in the branchial chamber. Three species of gobies were found in the burrows. These data show that burrows of U. yokoyai serve not only as a recruitment site for conspecific shrimp, but also as habitat for other animals in the tidal flat.

During a parasitological survey of the brown mussel Perna perna from highly productive culture fields in the southern sector of Brazil, monstrilloid copepods were discovered in the mantle of this mytilid bivalve. Numerous specimens of endoparasitic copepods were found within nodules in the mantle of the host; they belong to an undetermined species of Monstrilla. Monstrilloid copepods were known to be endoparasitic in polychaetes and in one species of prosobranch mollusc only; their occurrence as parasites of bivalve molluscs has not been previously documented. This is also the first record of these crustaceans infecting commercial molluscs. The prevalence of Monstrilla sp. infecting the brown mussel was 25.6%. At the histological level, it was observed that the larvae induced a strong haemocytic infiltration resulting from the complete larval encapsulation within the host mantle. The effect of this monstrilloid in the cultured populations of P. perna deserves further study.

Odontocymbiola magellanica is a neogastropod very common in Patagonian shallow waters. It feeds exclusively on molluscs inhabiting the same benthic community. Field studies showed that prey preferences are live gastropods (54%) and bivalves (46%). When no living prey are available they change their trophic behaviour to carrion or cannibalism. Feeding mechanisms observations showed that prey are not asphyxiated by the snail's foot as suggested before for the Volutidae family; they are narcotized by saliva introduced in a cavity made by the foot where prey are immobilized. Saliva is produced by the salivary (SG) and accessory salivary glands (AG) and has a pH around 10, relaxing prey muscles, which are consumed alive. Secretions from AG and aqueous extracts of SG and AG were mainly composed of proteins and glycoproteins, though SDS-PAGE gels revealed that salivary proteins were richer in higher molecular weight bands. Fractionation of secretions from AG on Bio-Gel P-100 yielded only one peak. SDS-PAGE showed that it consisted of only one band (MW 51.3 kDa). Microanalysis of cations showed a higher concentration of calcium and magnesium in the accessory salivary gland. Hypotheses of function of different glands are given in relation to feeding behaviour and anatomy of O. magellanica.

This study confirms the diet and determines the trophic position of the bentfin devil ray (Mobula thurstoni) and spinetail devil ray (Mobula japanica) in the south-west Gulf of California. There has been an active fishery in the area for these filter-feeding elasmobranchs, which are highly susceptible to exploitation due to low fecundity and long lifespan. However, information on their basic biology is scarce. δ13C and δ15N values of devil rays and zooplankton (sorted according to trophic level: herbivores, carnivores and omnivores) were determined over a period of 11 months, to allow for isotopic temporal variations in isotopic signals at the base of the food web. On the basis of fractionation factors we determined that bentfin and spinetail devil rays fed mainly on Nyctiphanes simplex, the most abundant euphausiid in neritic waters of the Gulf of California. The trophic positions obtained for the devil rays correspond to second level consumers.

Stomach contents of 893 blue shark (Prionace glauca) caught off Ensenada, Todos Santos Bay, Baja California, from 1995 to 1997 were analysed. 614 had identifiable food remains. A large variety of pelagic cephalopods occurred in 55.5% of all stomachs and accounted for 46.2% of all prey and 84% by estimated weight of stomach contents. The most abundant (17%) and frequent (32%) was Histioteuthis heteropsis and the most important by estimated weight (22%) was ‘Gonatus californiensis’. Argonauta spp. and Vampyroteuthis infernalis were also abundant prey. A pair of beaks of giant squid Architeuthis sp. constitutes the first record for Mexican waters. Feeding habits and the probability of scavenging on mesopelagic cephalopods is discussed. The single most abundant prey was the pelagic, red crab Pleuroncodes planipes (41.7%). Other prey included teleost fish, amniotes and floating items. Diet varied greatly between months with no clear seasonal pattern. Tiny diet differences due to shark size or sex were inconclusive. A thorough review of studies on blue sharks stomach contents analysis is given. Blue shark feed on a large variety of passive pelagic prey, mainly mesopelagic cephalopods, that could be preyed upon as well as scavenged. Depletion of this predator due to overfishing may be leading to unknown cascading top-down effects in the mesopelagic realm.

Common sole, Solea solea and Senegalese sole, S. senegalensis, were collected between January 2003 and June 2005 from commercial fishing vessels operating with gill-nets and bottom trawls along the Portuguese coast, to examine diet, age and growth and reproduction. Soles fed mainly on crustaceans, polychaetes and bivalves. Feeding activity was highest in summer, for males and for the largest individuals. Significant differences were found between the proportion of prey items according to season, sex and size-class. Common sole presented a wider dietary breadth compared to Senegalese sole. Dietary overlap between the two species was higher for the winter period and for females. Age of soles was determined from sagittae otoliths readings. The length of fish analysed varied between 187 mm and 462 mm (oldest fish 9 years), for S. solea, and between 199 mm and 472 mm (oldest fish 8 years), for S. senegalensis. The von Bertalanffy growth equation coefficients differed between sexes. For both species, the asymptotic length L∞ and growth coefficient k obtained for females were higher compared to those estimated for males. The highest values of the gonadosomatic index were obtained for the winter period, when the highest proportion of individuals at spawning stage was recorded.

The Galapagos Islands are among the most important nesting areas for the green sea turtle, Chelonia mydas, in the eastern Pacific Ocean. In addition, the coastal waters of this oceanic archipelago host many important feeding areas for this species, although little is known about green turtle feeding ecology at these sites. The goal of this study was to identify and quantify the most important items in the diet of the green turtle at the foraging grounds of Bahia Elizabeth, Caleta Derek and Punta Nuñez. Our analysis was based on 65 oesophageal samples from turtles captured in 2006 and 2007. We compared spatial and seasonal composition of diet using non-metric multidimensional scaling analysis (MDS) and analysis of similarity (ANOSIM). Green turtle diet was composed mainly of the algae species Ulva lactuca, Polysiphonia sp., Hypnea sp. and Dictyota sp., and the red mangrove Rhizophora mangle. Turtles also consumed animal matter, mainly cnidarians, albeit to a lesser extent. Content of turtle diets was different among feeding grounds and seasons. The ANOSIM showed that diet composition can differ between foraging grounds using presence/absence of diet items. Even though U. lactuca was the most abundant algae consumed in both seasons, changes in species richness of algae were found between both sampling events, with diet during the warm season more varied than the cold season (χ2 = 16.84, df = 6; P < 0.05).

The reproductive systems of 39 male and 54 female Bathyraja albomaculata were assessed microscopically and compared with macroscopic maturity index values assigned by scientific observers. Inconsistencies were limited to ‘developing’ maturity stages in both sexes, but such discrepancies were attributed to different factors depending on sex. Furthermore, while spermatozoa were observed in the oviducal gland of females, they do not appear to accommodate long-term sperm storage in this species.

Metabolism and growth rate of the hard clam, Mercenaria mercenaria, were investigated in a population invasive to Southampton Water, southern England. An individual metabolic model expressed as a function of soft tissue dry mass was fitted to data of 18 individuals (log (VO2) = −1.952 + 0.543 • log (DM); F1,16 = 201.18, P < 0.001, r2 = 0.926). A von Bertalanffy growth function was fitted to 227 size-at-age data pairs of 18 individuals (Ht = 80.13 • (1 − e−0.149 • (t−0.542)); r2 = 0.927). Individual age-specific somatic production was calculated, demonstrating increase with age to a maximum of 3.88 kJ y−1 at ten years old followed by decrease, and individual age-specific annual respiration was calculated, demonstrating asymptotic increase with age to 231.37 kJ y−1 at 30 years old. Results found here lie within the physiological tolerances reported across the biogeographical range, suggesting that the species' biogeographical limitation in the UK to Southampton Water results from ecological rather than physiological factors.

Microphytobenthos need photoadaptive strategies to survive the highly dynamic light environment in which they reside. Xanthophyll pigments can provide photoprotection by cycling electrons between epoxide and de-epoxide forms, dissipating excess light energy as heat. This study examined the xanthophyll cycle in microphytobenthos on a tidally exposed substrate at Browns River, Tasmania. Fv/Fm decreased from 0.52±0.01 to 0.47±0.01 at noon in surface samples and a decrease in the diadinoxanthin:chlorophyll-a ratio from 0.022±0.003 to 0.015±0.005 also suggests that the microphytobenthos was under physiological stress at noon. The results indicate that the cells exposed to light at the surface migrated deeper into the sediments and replenished the epoxide form of their xanthophylls. The results suggest that micrphytobenthos utilizes both behavioural and physiological strategies to survive in the dynamic intertidal environment.