The population dynamics and reproduction of the hermit crab Clibanarius vittatus were evaluated on Pescadores Beach, located on the estuarine channel of São Vicente (São Paulo), Brazil. The hermit crabs were captured by hand during low tide, from May 2001 to April 2003. A total of 2554 hermit crabs were captured, of which 701 were males, 1741 non-ovigerous females, 48 ovigerous females and 64 intersex individuals. The size–frequency distribution of the males was represented by a platykurtic bell-shaped curve, which differed from the leptokurtic bell-shaped curve of the females. The smaller and intermediate classes were composed mainly of females (modal size 6.5–7.5 mm carapace shield length (CSL)), and the larger classes only by males (modal size 9.5–10.5 mm CSL). The overall sex-ratio was skewed toward females (0.39:1/M:F), differing significantly from the expected 1:1. A seasonal reproductive pattern was recorded for C. vittatus in this location, with more intensive reproductive activity in the warmer months. The absence of juveniles suggests that their recruitment area is different than the area inhabited by adults, possibly another area with more protection and specialized or different resources for young.

Rafting on floating macroalgae is a common dispersal mechanism of marine benthic invertebrates. Most benthic macroalgae are inhabited by diverse epifaunal communities but not all organisms may be adapted to live on floating algae. In particular, knowledge about the immediate effects of algal detachment on the associated biota is limited. Herein, we studied the composition of the communities of mobile invertebrates on benthic thalli of Ascophyllum nodosum and compared it with detached thalli that had floated for short periods. The community of the mobile invertebrates changed significantly within the first minute after detachment of the algae and showed decreased diversity and a tendency towards reduced abundances in most taxa. However, during the subsequent two hours of floating at the sea surface the species composition did not change further. A comparison of the size-spectra of the gastropod Littorina obtusata from attached and detached algae did not reveal differential migratory activity among size-classes of these gastropods. Most of the species encountered in this study are common rafters in coastal and offshore waters, which are well capable of holding onto floating seaweeds. Therefore, our results indicate that the animals actively abandoned the macroalgae immediately after detachment. A benefit of this behaviour may be to avoid increased predation risk in the open water. The fact that individuals remain associated with their algal host after detachment indicates the importance of rafting dispersal for a great variety of phytal species that might lead to range expansion and regional population persistence through metapopulation effects.

Beach filling activities were conducted along the Mar del Plata coastline, Argentina, with sediments dredged from the harbour mouth between November 1998 and April 1999. We determined the percentage of imposex of Olivancillaria deshayesiana before, during and immediately after beach filling. The current situation (2005–2007) of imposex incidence was compared between populations from Mar del Plata and Mar Chiquita, a less impacted area. In addition, we evaluated differences in shell shape and body weight between females with and without imposex. The percentage of imposex was significantly higher during (85.3%) and after (73.9%) beach filling than before it (31.0%). No differences in body weight were found in the female population but shell length was significantly lower in females with imposex. As expected, the Mar Chiquita population showed no signs of imposex. This is the first report of imposex in beaches nourished with sand dredged from the port. Our results highlight the importance of analysing more carefully the sediment before beach filling. On the basis of the high level of imposex recorded near the port of Mar del Plata, O. deshayesiana can be used as a biological indicator of marine contamination with butyltin compounds.

Six new marine species of the testate amoebid genus Paulinella are described using light and electron microscopic observations of material from Canada's Pacific Ocean coastal waters. In order of test (shell) size, from smallest to largest, the following new species are proposed: P. carsoni sp. nov., P. agassizi sp. nov., P. suzukii sp. nov., P. lauterborni sp. nov., P. multipora sp. nov. and P. gigantica sp. nov. Included in this survey are new observations on P. indentata Hannah, Rogerson & Anderson, from Canadian Pacific Ocean locations, but previously known only from Scottish coastal waters, and the common brackish/freshwater species P. chromatophora, from Ontario (Canada). These new discoveries more than double the number of previously known species of Paulinella, a genus significant for its role as a secondary producer in marine benthic ecosystems and for the possible role of its type species (P. chromatophora) as a model system for the endosymbiosis hypothesis of the evolution of chloroplast-bearing organisms.

To determine the group structure of Sotalia guianensis on the coast of Paraná State, two bays, Baía de Paranaguá and Baía de Guaratuba, were surveyed between March 1999 and February 2000 and between July 2002 and June 2003 respectively. The heterogeneity of the studied areas was considered a relevant factor, therefore these areas were sectored and each sector was investigated independently. The surveys were carried out through boat line transects and all the animals were registered, even those localized between two transects. The records were taken for the quantity of groups as well as for the amount of individuals in each group and, whenever possible, the individuals were classified as calves or adults. The data were treated both separately and comparatively between the two bays and amongst the sectors of each bay. In Baía de Paranaguá, 735 individuals were registered, divided into 253 groups which varied from 2 to 37 individuals for an average of 2.9 individuals per group. Most of the groups presented a family formation (59.29%) and were observed during the morning. The individuals that were clearly identified as calves represented 24% of the total (176 individuals), adults 55% (405 individuals) and 21% (154 individuals) were impossible to determine. In Baía de Guaratuba, only 32 S. guianensis individuals were observed and distributed into 14 groups for an average of 2.13 individuals per group. These groups varied from 2 to 6 individuals mostly in family formations (50%). The same quantity of individuals and groups was observed during different periods of the day. Of the 32 sampled individuals, 25 (78%) were adults, only one was a calf (3%) and 6 (19%) were undetermined.

In gastropods, variation in shell morphology can be caused by the action of several biotic and abiotic factors. While much of this variation is seen in comparisons between different sites or populations, there is also substantial variation in shell morphology among individuals living side by side. We investigate the effect of trematode parasitism on both intra- as well as inter-site variation in the morphology of the New Zealand whelk Cominella glandiformis. We found that both infection by the trematode Curtuteria australis and site of origin had significant effects on several morphometric dimensions of the snail shell, with some interactions between the two factors. On its own, infection by C. australis accounted for 20 to 60% of the variance in shell morphology, depending on the dimension measured. Infected snails also had smoother shells, with less prominent ridges, than their uninfected conspecifics. Other trematode species, infecting whelks at much lower prevalence, also had impacts on shell morphology, but not necessarily in the same direction as C. australis. Overall, parasitism may be an important factor in explaining intra- and inter-site variation in snail phenotype, with potential repercussions for snail populations and their interactions with other community members.

Spectral sensitivity, visual pigment absorbance spectra and visual pigment opsin sequences were examined in younger shallow-living and older deep-living instars of the ontogenetically migrating lophogastrid Gnathophausia ingens. Spectral sensitivity measurements from dark adapted eyes and microspectrophotometric measurements of the rhabdom indicate maximal sensitivity for long wavelength (495–502 nm) light in both life history stages, but the younger instars are significantly more sensitive to near-ultraviolet light than the adults. Both life history stages express the same two opsins, indicating that there is no ontogenetic change in visual pigment complement between life history stages. Chromatic adaptation shifted the spectral sensitivity maximum to significantly longer wavelengths in both age-classes, but a distinct secondary short wavelength peak is visible only in the younger instars. These shifts appear to be due to the presence of migrating screening pigments, which are probably vestigial in the deep-living adults. Anomalies in the response waveforms under chromatic adaptation also apparently result from filtering by screening pigments, but via an unknown mechanism.

Sphaerosyllis sandrae sp. nov. (Annelida: Polychaeta: Syllidae) is described as a new species from shallow sandy bottoms off Guanahacabibes Biosphere Reserve (Cuba). Thirteen more syllid species belonging to nine genera (Exogone, Myrianida, Opisthosyllis, Parexogone, Plakosyllis, Salvatoria, Syllides, Sphaerosyllis and Syllis) have been found from algal and sand bottom samples from the same area; four species that belong to the genera Myrianida, Syllides and Parexogone are only identified at the generic level.

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.

Neohelice granulata is a crab found in salt marshes and mangroves of the south and south-eastern Atlantic coast of South America. Reproductive biology was studied by taking samples for two years at two salt marshes—‘Prainha’ and ‘Ilha’—in the estuarine region of Patos Lagoon (southern Brazil). Ovigerous females were found most of the year in both salt marshes with average CW ranging from 18.5 (Prainha) to 22.8 mm (Ilha). A significant linear relationship was found between log(CW) and log(number of eggs). Average size at the onset of maturation was 14.9 and 14 mm at Prainha, for males and females, respectively, while at Ilha it was 18.2 and 16.8 mm, for males and females, respectively. Results provided evidence of significant differences in reproductive traits between populations of the two salt marshes. Differences are likely related to the higher organic matter content found in the sediment from Ilha.

Size at the onset of sexual maturity was determined in Munida rugosa based on allometric growth of chelipeds and abdomen, and on the proportion of ovigerous females. The variability of three different measurements of carapace length (CL) used previously for M. rugosa was also evaluated to minimize measurement error. Both sexes had symmetrical cheliped length and allometric cheliped growth over the size-range investigated, but males showed increased allometry beyond 22 mm CL. Females had greater positive allometry in abdomen width than males, but their size at maturity could not be precisely determined because sampled females were too large.

The relatively shallow coldwater coral reefs growing off the eastern coast of Mingulay, north-west Scotland, are excavated by five sponge species, three of which, Alectona millari, Pione vastifica and Cliona lobata, were known previously from Scottish waters. The other two species are new to Scotland and Great Britain. One species is here described as new to science: Cliona caledoniae sp. nov. The species shows a superficial resemblance in colour (orange) and spiculation (possession of tylostyles and knobby microscleres) to Cliothosa hancocki described disjunctly from the Pacific Ocean and the Mediterranean Sea, but it differs clearly in lacking the characteristic Cliothosa amphiasters with branching rays. The Scottish species only possesses peculiar thick-rayed streptasters, which at first glance appear rather similar to the second microsclere type reported for Cliothosa hancocki, knobby-rayed amphiasters. However, the majority of the microscleres in the Mingulay species appear to be genuine spirasters (not amphiasters), and exhaustive search for true amphiasters, branching or otherwise, was in vain. The new species is extensively illustrated. Furthermore, we also report the first occurrence in British waters of Spiroxya levispira, originally described from Azorean deep waters, and subsequently reported from Madeira and several Mediterranean localities. It was found to occur not uncommonly in the Mingulay reefs, and additionally also in reefs of the Rockall Bank, west of Ireland. The spicular characters generally match those of the southern locations. The newly recorded species is described and amply illustrated.

A new free-living marine nematode species, Oncholaimus moanae sp. nov., is described from intertidal fine sand in southern New Zealand. Oncholaimus moanae sp. nov. can be distinguished from other species of the genus by the presence of a pre-cloacal papilla bearing four pairs of short, stout spines, a post-cloacal papilla, long (>70 μm) spicules, and a demanian system with two openings situated laterally at level of uvette. The δ13C signature of O. moanae sp. nov. suggests that benthic microalgae are the main carbon source for this species, but an elevated δ15N signature suggests predatory feeding habits. The fatty acid composition of O. moanae sp. nov. is rich in highly unsaturated fatty acids, which are likely to originate from heterotrophic protists (e.g. ciliates). The data obtained in this study suggest, for the first time, that marine nematodes can be a high quality food source (i.e. rich in highly unsaturated fatty acids) to predators. Large nematodes living near or at the sediment surface, in particular, may represent an important trophic link between heterotrophic protists and higher trophic levels in marine sediments.

Humpback whales (Megaptera novaeangliae) have a worldwide distribution in the oceans and are known for their very long migratory potential. Their migration routes consist of productive feeding areas located in high-latitudes and to low-latitude areas used as breeding and calving grounds. Genetic studies in humpback whale populations consist mainly of nuclear and mitochondrial DNA. In general, these studies provide similar results to estimates of gene flow, but some discrepancies may be caused by gender-biased migration to breeding grounds and further dispersion by males. There is little evidence of trans-equatorial and inter-oceanic migrations, but those movements have been confirmed by both analysis of photo-ID of naturally marked individuals and also genetic analysis. The combination of migratory and genetic analyses suggest an overlapping of breeding grounds in low-latitude areas, where the gene flow among those oceanic populations is more likely to happen, despite the opposite seasons in the northern and southern hemispheres. These results have important implications in the conservation perspective, especially for the determination of protected areas and for development of international agreements.

Dasybranchetus pacifica, collected in Concepcion Bay, Baja California Sur, Gulf of California, is described as a new species. In addition, the type species of the genus, Dasybranchetus fauveli Monro, 1931, is redescribed based on type material. The new species differs from D. fauveli in the absence of branchiae, the begining of the mid-dorsal lobe from chaetiger 2 instead of chaetiger 9, abdominal segments with well-developed neuropodial lobes, and hooded hooks with a main fang and three rows of subapical teeth in the following arrangement: 4 teeth in the basal line, 3 in the middle line, and 2 in the apical line.

The aim of the present study was to provide the first analysis of depth distribution and reproductive biology in the deep-sea cirrate octopus Opisthoteuthis calypso along the Portuguese continental slope. We used 77 specimens obtained in 7 research cruises between 1996 and 2003. Catch rates and biomass, weights, lengths, sex and maturity stages, and a morphometric description of the beak are detailed. Specimens have been collected from 553 to 960 m depth, south of 39°N, in approximately 1:1 sex-ratio. Females are larger (80:75 mm mantle length) and heavier (622:346 g total body weight) than males and both sexes have been caught in all stages of maturity in equal proportions.

The different stages of embryonic development of the porcellanid crab Pachycheles chubutensis are described, along with the chronology of each stage at 16±1°C. Five different developmental stages (I–V) were recognized including: (i) early cells and 100% of the vitellum; (ii) formation of the embryonic primordium at the animal pole of the egg; (iii) presence of dark pigmentation on the posterior part of the ocular globe; (iv) appearance of chromatophores on mouth parts and in the abdominal zone; and (v) eye pigmentation in circular–oval form, filling the entire surface. The embryonic development lasts from spawning to hatching approximately 21 days, with the second stage being the longest.

Both the need for shelter and the need for food can be motivations that alter animal behaviour. We tested the hypothesis that the hermit crab, Pagurus samuelis, deprived of food, shells, or both will respond differently from control hermit crabs when presented with food and shells concurrently. We measured the number of contacts made with both food and shells, and time elapsed until hermit crabs either began feeding or inserted into shells. We interpreted making few contacts and initiating behaviour quickly to be an indication of short decision time and high motivation; whereas, making many contacts and having long initiation time indicated a long decision time and low motivation to acquire resources. Control (C) hermit crabs made 72% more contacts with food and 53% more contacts with shells than shell-less (S) crabs. Control hermit crabs also made 34% more contacts with food and 35% more contacts with shells than starved and shell-less (StS) hermit crabs. This suggests that S hermit crabs were more motivated to acquire shells than C crabs. In addition, StS hermit crabs chose to insert into provided shells, while hermit crabs remaining in their shells chose to feed. Results indicate that being shell-less is a stronger motivation than being starved, such that finding shelter takes priority over finding food when both are needed. In rocky intertidal environments, resources such as food and shells are likely to be ephemeral. Hermit crabs that are motivated to make appropriate decisions to acquire specific resources may have a distinct advantage over those that are distracted by numerous objects in their environment.

This paper describes the organism–organism relationship between a bivalve host and larval digeneans. The studied population of the stout razor clam Tagelus plebeius from the mixohaline Mar Chiquita lagoon (37° 32′S 57° 19′W) showed 100% of prevalence of infection by a larval digenean (metacercaria) of the family Gymnophallidae. The larvae occupied the extrapallial space just below the hinge of the bivalve. The tissue reaction against larval digeneans by T. plebeius consisted of hyperplasia and metaplasia of the outer layer of the mantle epithelium adjacent to parasites, forming an invagination to generate a sac that surrounded gymnophallid larvae. According to the intensity of infection, each sac progressively enlarged to harbour a variable number of larvae. In highly infected clams, a great number of sacs are formed. Eventually, the older sacs containing larvae may become closed, losing their communication with the extrapallial space and sinking into the dorsal part of the visceral mass. Larvae within sacs grow and remain alive until they reach an appropriate definitive bird vertebrate host. Older lesions commonly showed remains of dead larvae which had undergone resorption. As a result, an orange to brownish amorphous material accumulated in the space once occupied by the larvae leaving conspicuous orange marks on the inner surface of the valves. In some cases, calcifications in the form of pearls or blisters were observed.

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.