We examined habitat, population size-structure, colour dimorphism, reproductive behaviour, arm loss and the relation between arm regeneration to pyloric caeca indices in populations at Whitford Rock (WR) and Port Beach (PB) in January 2009. The sediment was fine sand at WR and a mix of larger particles at PB. Individuals at PB were predominantly orange and more uniform in colour than those at WR, which were predominantly grey. Body size and pyloric caeca index of individuals at WR were greater than those of individuals at PB, indicating the nutritional condition was better at WR. This suggests the quantity or quality of food at WR was better. Organic matter of the pyloric caeca and body wall of intact and regenerating individuals at both sites were similar, indicating loss of an arm did not affect gross proximate composition of the organs. Sea stars with regenerating arms made up 5.4 and 8.4 % of the populations observed. Despite the very small size of the gonads, some individuals were in the pseudocopulatory position, indicating this behaviour occurs even when gametes are not present. In every case observed, the male of the pseudocopulating pair was situated above the female. Given the abundance of this species in nearshore habitats dominated by sediment, it is likely to be ecologically important. However much of the biology and ecology of the species, even its diet, remain unknown. This together with its unusual mode of reproductive behaviour involving pseudocopulation, which is only known from two other species of asteroids, underscore the need for more research on Archaster angulatus.

We examined the population dynamics and life history characters of the boreal larvacean Oikopleura vanhoeffeni in Conception Bay over two years and determined its role in secondary production. Based on the analysis of age structure inferred from statolith diameter, the generation time was approximately one year. Recruitment of new cohorts and maximum population growth rate occurred in the spring. Somatic growth rate was 0.017 d−1 from the year 2001 to 2002 and 0.043 d−1 from 2002 to 2003, with an acceleration in growth rate during April in response to the spring diatom bloom despite the coldest water temperatures. The annual production rate (i.e. somatic + house production) of 8.7 g C m−2 y−1 in 2001/2, and 3.8 g C m−2 y−1 in 2002/3, represented 2.9–6.7% of primary production and 37–87% of estimated mesozooplankton production, suggesting that O. vanhoeffeni is a major secondary producer in Conception Bay. Individuals matured at seasonally variable body size throughout the year and potential fecundity peaked as the individuals matured at their largest body size during the spring bloom, most likely resulting in maximum egg production and population growth rates at that time of year. Thus, a seasonal pulse of food is a major driving force that regulates the variation in life history characters and population dynamics of the boreal O. vanhoeffeni.

Seven populations of Holothuria polii were sampled from the eastern and western Mediterranean coastal waters of Tunisia and screened electrophoretically for genetic variation at 11 allozyme loci. Six among the seven polymorphic loci were out of Hardy–Weinberg equilibrium (HWE) in at least one population. In the same way, the multilocus test showed deviation from HWE in all populations. These populations showed heterozygote deficiency. Genetic variability was relatively low. The number of alleles per locus ranged from 2.09 to 2.27 (average = 2.15), and the observed heterozygosity varied between 0.14 and 0.20 (average = 0.17). The observed overall differentiation among populations was slight but significant, with a mean FST value of 0.024 (P < 0.001). Pairwise FST values reflected the differentiation of the two populations, which were at the margins of the range sampled, from all the others. Our data suggest a population structure consistent with separation by Mediterranean Sea basins that might reflect different local biogeographical zones.

The bivalves Mytilus chilensis, Venus antiqua, Mulinia edulis and Tagelus dombeii inhabit different levels of the tidal flats in Yaldad Bay, southern Chile. Mytilus chilensis is an epifaunal bivalve, which, at this location, is also farmed in culture rafts; whereas the other species belong to the infauna. The objective of this study was to compare filtering capacity of these species; in order to do this, measurements of food consumption were taken by quantifying clearance rates, as well as taking morphological measurements of their feeding systems (gills and labial palps), and endoscopic observations to determine the velocity of particle transport within the gills. All of these parameters were related to the sediments present in environments occupied by these species. In Mytilus chilensis, both wild and farmed, gill area was significantly higher than in the three infaunal species. Mulinia edulis and Venus antiqua did not show any significant differences in gill area. As far as Tagelus dombeii is concerned, the species presented the lowest values among all species studied. Weight of labial palps was significantly higher in Mulinia edulis compared to the other species. There were no significant differences between labial palps of either wild or farmed Mytilus chilensis or in those of Venus antiqua and Tagelus dombeii. A positive, significant relationship was identified between labial palps size and mud sediment content. Both culture-rafts and intertidal Mytilus chilensis displayed a clearance rate that was significantly higher than the infaunal species, concurring with a significant relationship between clearance rate and gill area in the different species studied. Clearance rates displayed by Venus antiqua, Mulinia edulis and Tagelus dombeii did not show significantly different results among them. Mytilus chilensis from both culture-rafts and intertidal zone displayed higher values of particle transport velocity than the infaunal species. Particle transport was not observed in the dorsal canal of any of the species studied. The conclusion is that in these species filtering capacity is determined mostly by gill size and that labial palp size displays a strong relationship with sediment content in the mud of Yaldad tidal flats.

Mussismilia braziliensis is endemic to the south-western Atlantic, where it plays an important role as a major reef builder. It occurs in a wide range of sediment conditions between coastal and offshore environments. Here, we investigated its reproductive effort along an inshore–offshore gradient. Three sites were sampled with varying distances (15 to 60 km) from the mainland in the Abrolhos Reef Complex (18° S). Reproductive effort was estimated as fecundity (number of eggs per: polyp, cm2, mm3, and mesenteries). Mean fecundity per polyp was 338.7 (±73.5 SD) and the highest number of eggs per polyp was 987. Percentages of fertile mesenteries per polyp were similar among sites. However, the fecundity per mesentery varied among colonies and among sites. Fecundity per polyp increased as its area, volume, height and number of fertile mesenteries increases. The area closest to the coast (‘Pedra de Leste’) presented the highest mean fecundity per polyp (410 eggs ± 159.2 SD), cm2 (233.47 eggs ± 219.44 SD), mm3 (4.95 eggs ± 2.34 SD) and mesentery (10.6 eggs ± 4.3 SD). Corals closest to the coast had 55% higher fecundity per polyp and 64% higher fecundity per cm2 than corals offshore. This area presented the highest contribution of non-carbonate sediments deposited on the reefs. Therefore, we suggest that colonies of M. braziliensis may present higher uptake rates of particulate matter at inshore reefs, which allow for higher rates of tissue growth (less nutrient limitation) and energy allocation to reproduction.

Functional morphology of the male gonopods, female holding systems and vulvae of Libinia spinosa are described using scanning electron microscopy and histological sections, establishing differences between immature and mature individuals. The first gonopod of mature males, larger than 35.1 mm of carapace width (CW), is long, slender, and ending in two wing-like processes; abdominal, characterized by the presence of a sub-terminal seminal canal, and sternal, closed and where the cuticle holds setae. In immature males, smaller than 29.9 mm CW, both processes are shorter, and the tip of the abdominal process closed. Six different types of setae are described for both gonopods. Internally, the gonopods have rosette glands in immature and mature individuals. The presence of secretions, which may be involved in the moulting process, was observed in immature males towards the external cuticle corresponding to the rosette glands. The rosette glands may be related to reproduction in mature males. Females presented a press-button holding system and a biconcave vulva. In immature females, smaller than 36.1 mm CW, the vulva aperture was closed by integument bulging to the outside. In mature females, larger than 42.6 mm CW, the locking system was almost fused to the cuticle, and the vulvae showed an open biconcave form with a more inner flexible membrane. Morphological characteristics shown by the gonopods of mature males develop synchronously with the acquisition of physiological maturity, not with morphometrical maturity. The mature holding systems and vulvae of females are developed synchronously with physiological and morphometrical maturity.

The spiny dogfish Squalus acanthias is widely distributed in Atlanto-Mediterranean regions, being captured off the Languedocian coast (southern France, northern Mediterranean), despite a decline of landings. The male and female sexually matured between 635–700 mm and 860–880 mm total length (TL), respectively. The largest male and female were 800 mm and 1110 mm TL, respectively and weighed 2220 g and 8900 g, respectively. There was a significant relationship for total mass versus TL, and liver mass versus TL between males and females. The diameter of the largest yolky oocytes ranged between 43 and 47 mm (mean 45.08 ± 0.98), while the mass ranged between 29.5 and 37.4 g (mean 31.79 ± 2.20). Near- term embryos ranged from 245 to 271 mm TL (mean: 258.85 ± 7.28) and weighed from 47.5 to 55.9 g (mean 53.35 ± 2.26). Ovarian fecundity ranged from 6 to 15 (mean = 10.38 ± 2.66). Uterine fecundity or litter size ranged from 4 to 12 (mean = 8.15 ± 2.07). Both fecundities showed a positive relationship with TL of females. A chemical balance of development based on mean dry masses of yolky oocytes and near-term embryos was 0.87 and suggested that S. acanthias is a pure lecithotrophic species. Hepatosomatic index (HSI) and gonadosomatic index (GSI) significantly increased with size in both males and females. HSI reached the highest values in both sub-adult and adult specimens, reflecting the role of the liver in the gonadal production as well as in buoyancy, while in the GSI the highest values were observed in pregnant females. Vitellogenesis proceeds in parallel with embryonic development. Near-term females were captured in different months of the year while a short period of resting could not be excluded between parturition and the beginning of a new pregnancy, so it appears difficult to delineate the length of gestation. However, a reproductive cycle with a wide range from 18 to 24 months remains a suitable hypothesis.

This study of the little known north-eastern Atlantic mytilid Modiolarca subpicta suggests a more intimate relationship with ascidians and, especially, Ascidiella aspersa, than has hitherto been appreciated. Both live for ~18 months and the reproductive cycle of both is approximately co-ordinated so that juvenile ascidians become available as hosts to the settling spat of the symbiotically epizoic M. subpicta each summer. Settling spat of M. subpicta are thought to be attracted to the exhalant flow from the ascidian's anal siphon. After the ascidian's death, the liberated mussels may adopt a wandering, free-living, lifestyle they have occasionally been reported to pursue. Anatomically, M. subpicta is of the typical mytilid plan, albeit simplified commensurate upon its normal lifestyle of protective envelopment within the host's tunic. The foot, however, is highly mobile and in addition to being used for locomotion, especially in juveniles, is responsible for the planting of byssal threads, typically dorsally above the shell, so that each individual stimulates the ascidian to produce an epidermal pocket into which it manœuvres itself and reposes, securely attached, but dorsal side down Modiolarca subpicta, epizoic in the tests of ascidians, could have evolved from a more isomyarian, equivalve, ancestor via a nestling, epibyssate, Trichomusculus-like shaped intermediary with ventral flattening and, hence, stability characteristic of the more familiar heteromyarian mytilids of rocky shores and lotic freshwaters being achieved through living dorsal side down.

Hamel et al. (2008) reported that veliger larvae of the nudibranch gastropod Palio dubia settled 1 to 3 days after hatching and that metamorphosis commenced shortly thereafter. This is an anomalously short larval period for a nudibranch described as having planktotrophic development. I examined the embryonic development and hatching larvae of P. dubia collected intertidally from Maine, USA. Veliger larvae with shells 120 μm long and lacking eyespots and propodia developed in 7 days at 20°C from eggs averaging 69 μm in diameter. Their size and morphology were typical of planktotrophic nudibranchs known to have minimum larval periods of weeks to months, and the available evidence does not suggest any other mode of development exists in P. dubia. The larval period of P. dubia is likely an order of magnitude longer than reported by Hamel et al. (2008).

The morphostructures of larval and juvenile shells of two common species of bivalves of the north-western Sea of Japan, Mytilus trossulus and Crenomytilus grayanus have been examinated. Two types of morphological features were identified on the basis of the results obtained and comparison with materials of other species of the subfamily Mytilinae. One group of morphological features (absence or presence of the nepioconch; form and size of posterior lateral teeth) characterizes the higher taxonomic categories, while the other one (morphological details of general outline of the secondary prodissoconch and juvenile shell; ratio shell height/length; form, size and number of provincular and additional teeth; number of posterior lateral teeth, and others) serves to separate taxa of the generic or specific ranks.

Eight species of Yoldiella (Yoldiella biguttata Allen, Sanders & Hannah, 1995; Yoldiella similis Allen, Sanders & Hannah, 1995; Yoldiella extensa Allen, Sanders & Hannah, 1995; Yoldiella aff. jeffreysi (Hidalgo, 1877); Yoldiella sp.1; Yoldiella sp. 2; Yoldiella sp. 3 and Yoldiella sp. 4) from the continental slope off Rio de Janeiro were used to test if quantitative morphometric measurements of shell shape and hinge plate could effectively discriminate among them. Thirty specimens of each species were sampled, and a total of 25 variables were established and utilized as input data to perform a discriminant analysis. The percentage of correctly classified cases was never less than 80%. The hinge plate variables were always relevant, and the most important one was the width of the posterior hinge plate. On the other hand, shell shape variables, when present, were secondary. Considering that the variation in the shell of Yoldiella species is subtle, and also the findings of this study, we can state that the hinge plate morphometry has good potential to improve species discrimination.

The trematode Parorchis acanthus is widely distributed and exhibits a broad host spectrum, with larval stages occurring in marine gastropods and adult flukes parasitizing on various seabird species. Unlike the majority of digeneans, its cercariae do not invade a second intermediate host but encyst on a substrate in the open. In a series of laboratory experiments, we investigated factors influencing cercarial emergence and settlement of P. acanthus. Emergence of cercariae from the gastropod intermediate host Nucella lapillus increased with increasing temperature, whereas cercarial encystment success decreased. Numbers of emerged cercariae were highest in the presence of light and water. However, although in much lower numbers, cercariae were also released from N. lapillus and successfully encysted under relatively dry conditions. Cercariae were found to settle predominantly on filtering blue mussels Mytilus edulis, suggesting that cercarial concentration on the valves is largely facilitated by the bivalve's inhalation current. After being inhaled, cercariae actively emerged from the mussels using their suckers and subsequently encysted on the shells, preferably along the rim of the valves. Barnacle epibionts Semibalanus balanoides were observed to impair cercarial settlement on mussels, by disturbing or preying on cercariae. Whilst settlement success of cercariae on M. edulis increased with increasing mussel density, intensity of encysted metacercariae decreased. Furthermore, cercariae settled more efficiently on small than on large mussels. Our findings suggest that the transmission of P. acanthus cercariae is regulated by a range of abiotic and biotic factors, with filtering activity of mussels playing a key role by enhancing accumulation of cercariae on a substrate suitable for transmission to the bird final host.

We estimated the prevalence of the bopyrid Pseudione galacanthae parasitizing the population of the squat lobster Munida gregaria in San Jorge Gulf and analysed some aspects concerning the effect of the parasite on host reproductive potential. The relationship between the development stages of the parasite and the host size was also analysed. The squat lobsters were caught as by-catch in the coastal area of the gulf from vessels operating in the fisheries of hake Merluccius hubbsi, southern king crab Lithodes santolla and Argentine red shrimp Pleoticus muelleri. The samples were collected between October 1997 and June 2009. In the laboratory, squat lobsters were sexed and the length of their carapace was measured. In males, the length of the right cheliped was recorded and gonadal development was examined. In females, the size and number of carried eggs were determined and the length of the pleopods III, IV and V were measured. All squat lobsters parasitized exhibit a gross bulge in the right side of carapace. Prevalence ranged between 0 and 1.43% (N = 21,519). No significant differences in prevalence were found for sexes, depths and seasons. The prevalence was higher for the size interval 7–10 mm CL (0.79%) than for the rest of the intervals. Parasitism had no effect on the secondary sex characters. Parasitized males displayed gonad development. There was no difference in prevalence between ovigerous and non-ovigerous squat-lobster females. Parasitized females had smaller eggs than non-parasitized ones, but their fecundity was similar. The linear relationship between the parasite and host sizes and the presence of larvae and immature stages of P. galacanthae in small-sized squat lobsters suggest that the host is infected early in its development. The low prevalence could be related to oceanographic conditions which favour larval dispersal of the parasite and host. The infestation by P. galacanthae has little impact on the M. gregaria population, mostly due to the low prevalences of infestation and the minor impact in reproductive function.

The aim of this work is to study the variation of the global chemical composition of six fish species (Lithognathus mormyrus, Mullus barbatus, Mullus surmuletus, Pagellus erythrinus, Pagrus caeruleostictus and Dentex maroccanus) caught by the trawl of the Gulf of Gabès (Mediterranean Sea). The variations of the chemical contents of the fish as a function of size, sex, organs and parts of the muscle were examined between December 2005 and May 2006. ANOVA indicated that the global chemical composition was significantly affected by two factors: species and body locations (parts of the muscle). The correlation matrix established between the chemical contents showed two highly significant correlations (fat–moisture and protein–ash). The discriminant analysis allowed the distribution in the space of fish species into five groups according to their moisture, proteins, fat and ash contents. The analysis of the fat content in the parts of the fish body revealed the presence of a concentration gradient.

Oceanic juvenile loggerhead sea turtles, Caretta caretta, foraging in Azorean waters, are incidentally caught in drifting longlines that target swordfish, Xiphias gladius, and blue shark, Prionace glauca. Data were recorded during a longline gear modification experiment conducted in 2000. The results show that the captures are not uniformly distributed in relation to fishing effort, with 81% of the loggerheads (N = 232) caught in one-third of the sets (N = 93). The highest turtle catch rates were around the eastern group of islands, an area characterized by the presence of mesoscale eddies induced by bathymetric features. High catch rates coincided with the presence of the thermohaline front, between August and October, and when targeting blue shark. To investigate the causes of these differences we fitted a general linear model to evaluate the influence of mean depth, minimum depth, sea surface temperature (SST), soak area, soak time, moon phase and wind force on turtle and target species catch rates. These results revealed that mean depth and SST were most important for loggerhead catch rates, while minimum depth was the only significant variable for swordfish and mean depth, SST, wind force, moon phase and soak time influenced blue shark catches. The distribution of loggerhead sea turtles can be predicted by monitoring fishing areas in relation to bathymetry and SST. The impact of longline fishing could be greatly and quickly reduced by regulating the blue shark fishery and by increasing fishermen awareness for sea turtle conservation.