The cumacean Cumopsis goodsir (Crustacea: Peracarida) was sampled monthly in 1991–1992 in the surf zone of Creixell Beach (north-western Mediterranean), to describe its life history and secondary production. In this unstable coastal soft-bottom area, C. goodsir is one of the dominant species of the subtidal community. The annual mean density of this population was 8.5 ind 5 m−2 and the corresponding mean biomass was 0.19 mg 5 m−2. The overall sex-ratio was statistically in favour of females (F:M=2.1). Brooding females were collected regularly during the whole year and their mean fecundity was estimated at 19.3 ind per marsupium. The demographic analysis of samples suggested that C. goodsir is a trivoltine species. The potential longevity of individuals is less than one year and differs between generations. Using the sizefrequency method, its annual production was estimated at 1.44 mg ash free dry weight 5 m−2 year−1 with a corresponding annual ratio of 7.79.

A total of 11 polydorid species of the family Spionidae were extracted from non-calcareous substrata from Japan. The polydorids were: one Polydora sp., Polydora cornuta; three Dipolydora spp., Dipolydora quadrilobata, D. cardalia, D. socialis; one Carazziella sp., Carazziella spongilla; one Boccardiella sp., Boccardiella hamata; two Boccardia spp., Boccardia perata, B. proboscidea; three Pseudopolydora spp., Pseudopolydora cf. kempi, P. antennata, P. paucibranchiata. All inhabited mud deposits including mud in crevices of calcareous substrata, sponge and sandstone rocks, and were never found in self-excavated burrows in calcareous substrata. This study attempts to summarize and discuss the taxonomic, morphological, and behavioural characteristics of these non-boring species inhabiting Japanese waters and to compare them with the previously known boring species. The 11 non-boring species belonged to six genera. Thus their taxonomic and morphological variability was higher than those of boring species, which belonged only to three genera. A generic overview suggests that some genera contain many species capable of boring and others contain many species incapable of boring. Branchial blood vessels were thick and conspicuous in non-boring species. Moreover, they showed high crawling activity and a strong, vigorous palp movement. These observations suggest a possible link between boring activity and the morphology and behaviour in polydorids. In addition, Polydora cornuta, Dipolydora quadrilobata, D. cardalia, D. socialis, Boccardia perata and Pseudopolydora cf. kempi are new to Japan.

Several specimens of monstrilloid copepods were collected in different localities of Brazil between 1993 and 1997. The taxonomic analysis of these specimens yielded the identification of two new species of Monstrilla. The first one, M. careli sp. nov. can be distinguished by a combination of several characters, including its body proportions, with a very long cephalothorax, by the particularly long terminal segment of the antennules, by the structure of its fifth legs, and by the very long dorsal seta on the caudal rami. The second species, M. brasiliensis sp. nov. can be distinguished by the peculiar features of its fifth leg, with a patch of long and stout hair-like setae along its outer margin; it has also a notched protuberance near the antennule bases. It has a notch on the anterior protuberance of the genital somite, and a ventrally swollen cephalothorax. This species, together with M. inserta Scott bears a pair of enigmatic structures which are either modified sensillae or a vestigial postantennular appendage not previously described in the Monstrilloida.

During the austral spring (December 1996), numerical abundance of copepod species (Crustacea: Copepoda) was estimated from 53 sampling stations scattered over the coastal waters off Mejillones Peninsula, northern Chile. Samples were obtained from two depth strata; 0-50 m and 50-200 m depth. Oceanographic data over the three-day cruise indicated that coastal upwelling was actively occurring during the survey.

A total of 19 species was identified, of which four of them, Paracalanus parvus, Oncaea conifera, Oithona similis and Calanus chilensis, accounted for more than 80% of the whole copepod assemblage in terms of numerical abundance. Using the K-means exploratory analysis the 53 locations were grouped into two clusters: an upwelling type and a non-upwelling type. The former characterized by locations nearshore, with low temperature (<17°C) and high chorophyll-a (>13.4 mg m−3), while the latter had warmer waters (>18°C) and low chlorophyll-a (<4.8 mg m−3). Chlorophyll-a (chl-a), distance to shoreline and temperature at 10 m depth (T10) were all significant variables ( P<0.05) for clustering analysis. There was a strong negative correlation between T10 and chl-a ( P<0.01). The same clustering technique, based on species abundance, suggested the presence of a unique cluster, whose composition was dominated by P. parvus, O. similis, Acartia tonsa and Centropages brachiatus. Stepwise multiple regression showed that these species were also strongly correlated to chl-a and T10. Together these analyses suggest that water mass circulation during upwelling is the driving force for structuring spatial patterns of copepod distribution. In addition, a vertical distribution parameter suggested that copepods, independently of time of the day, tended to remain in a large proportion in near surface waters, possibly constrained by a shallow oxygen minimum layer. This implies that advection during active upwelling may cause large fractions of populations being transported offshore, allowing zooplankton export to more oceanic waters. Rapid turnover rates of copepods growing continuously year-round, may act as a mechanism to compensate population losses during persistent coastal upwelling.

The ovary structure of the hermit crab Diogenes pugilator (Crustacea: Decapoda), is described in the different phases using electron microscopy. Sexual maturity was reached at a very small size; females from 0.74 mm shield length (SL) could be found in vitellogenesis stage and even 0.6 mm SL ovigerous females exist. The biometric study of the ovigerous females by independent size-class (non-accumulative) shows that 1.3 mm SL is the size at which 50% of females are ovigerous; this value is increased a little (1.7–1.8 mm) if the population of females, or ovigerous females, is analysed from an accumulative point of view. In addition, an optimal reproductive size (between 2.1 and 2.3 mm SL) and a reproductive decrease in the maximum size-classes have been detected. The relation between brood size (measured through egg number) and the hermit crab size follows a potential function. The number of eggs by brood varies in a wide range (9–2838), with a mean diameter of 0.35±0.03 mm. No relationship between egg size and shield length has been found.

Larval development of Capitulum mitella (Cirripedia: Pedunculata) comprises six nauplius stages and a cyprid. Unilobed labrum, a larval trait of pedunculate and chthamalid barnacles, bears two groups of slender hairs and two pairs of strong teeth on the distal labral margin, and a pair of teeth on the lateral labral margin. Frontolateral horns extended under the anterior cephalic shield margin are diagnostic features through all nauplius stages. The posterior border of the cephalic shield bears a pair of distal cephalic shield spines in nauplius stages II and III, and a pair of long posterior shield spines in nauplius stages IV, V and VI. A hispid seta is consistently found at the fourth group of the antennal endopodite through stages II–VI. The dorsal thoracic spine, abdominal process and the paired posterior shield spines have numerous small spines. Morphological features such as the cephalic shield, labrum, abdominal process, antennules, antennae and mandibles in all nauplius and cyprid stages are illustrated and described. In this species, the numerical setations of the antennule are found to be beneficial for intra-specific identification of barnacle nauplius stages without the need for dissection.

The porcellanid crab Liopetrolisthes mitra is a common associate of the black sea urchin, Tetrapygus niger in north central Chile. The host-use pattern, population dynamics and reproductive pattern of L. mitra on sea urchins were examined between January 1996 and February 1997. Each month, between 60 and 95 per cent of all collected urchins hosted crabs, with the highest frequency of cohabitation occurring during the austral summer (January to March). Group sizes of crabs on individual urchins ranged from 1 to 25 crabs per host. The average density of crabs on the urchins ranged from 2 to 5.5 crabs per host. Large urchins were inhabited by crabs more frequently than small urchins but urchin size had no effect on the number or size of crabs. The sex ratio of adult crabs was ˜1:1 during most months. Reproduction occurred throughout the year but was most intense during the austral spring and summer (October to March), when the highest percentage of ovigerous females were found. Similarly, recruitment of L. mitra occurred throughout the year but reached a peak during austral summer and early autumn (January to May). All life stages of L. mitra including recently settled megalopae and reproductive adults were found on urchins. Size–frequency analysis indicated that many crabs live >1.5 years. The results of this study confirm that the association between L. mitra and T. niger is strong and persists throughout the benthic life of the commensal crab.

The shell and internal anatomy of the montacutid bivalve Mysella verrilli is described for the first time. The species is remarkable in that the oesophagus has developed into a suctorial proboscis. This has been accompanied by the loss of the palps. In addition the gonads have been extended from the dorsal part of the body to form two gill-like extensions to which the reduced inner demibranchs attach along the postero–ventral margin. Mysella verrilli broods its young in the mantle cavity to the late veliger stage before releasing them. It is believed that the species is probably a suctorial ectoparasite on a soft-bodied benthic invertebrate.

This paper describes two new species from the genus Dorymenia (Mollusca: Solenogastres: Proneomeniidae): D. hesperidesi sp. nov. and D. menchuescribanae sp. nov., collected during the Spanish oceanographic expeditions for the study of Antarctic benthos, BENTART'94 and BENTART'95, carried out in the area of the Livingston Island (South Shetland Islands, Antarctica). A comparative study of main specific characteristics of species belonging to the genus Dorymenia found off the South Shetland Islands and in the Bransfield Strait (Antarctica), is also included.

The present work provides a first description of three planktonic larval stages of Chorismus tuberculatus which were obtained from plankton samples collected in the south-western Atlantic during the expeditions of the RVs ‘Walther Herwig’ and ‘Shinkai Maru’ in 1978 and 1979, respectively. Three early developmental stages of C. tuberculatus are described and compared with those of the second species of this genus, C. antarcticus which is known to be distributed in the southern Atlantic Ocean and Antarctica. Both species are distinguishable by the presence/absence of supraorbital spines at the carapace, an anal spine and the exopodite on pereiopod 4. The rostrum is less developed in C. tuberculatus, the shape of the somites is less pronounced, and the number of posterior spines at the telson is lower than in C. antarcticus. Due to an abbreviated larval development as a physiological adaptation to it wider distribution into the Polar region, we assume C. antarcticus to have phylogenetically separated from C. tuberculatus, represented by the well developed first larval stages in contrast to that of the species described herein.

This paper presents the first record of Ceratothoa steindachneri from Cornwall, making it the first resident species of the fish–parasitic isopod family Cymothoidae in Britain. The host is Echiichthys vipera (Trachinidae) the lesser weever fish, the isopod attaching to the host tongue. A complete redescription and reillustration for C. steindachneri is given, and a neotype is selected for the species Ceratothoa parallela. A key to the north-east Atlantic and Mediterranean species of Ceratothoa is included, with a brief illustrated account for each species.

The combined effects of cadmium (Cd) and temperature on the physiology (oxygen consumption rate (MO2)) and biochemistry (glycogen, metallothionein (MT) and Cd concentrations) of fasted dogwhelks Nucella lapillus were investigated using two Cd concentrations (<0.01 or 500 μg l−1) and two water temperatures (5 or 10°C). After 20 days of exposure, the MO2 of dogwhelks of various sizes (12—32 mm in shell length) were measured individually. Dogwhelks exposed to Cd exhibited significantly lower MO2 at 10°C but not at 5°C when compared with controls at the same temperature. Inhibition of MO2 by Cd increased with increasing water temperature and decreasing animal size. Cadmium exposure caused significant reductions in glycogen concentrations in foot muscle and digestive gland at both temperatures. Cadmium-exposed dogwhelks showed significantly higher MT concentrations in the Leiblein gland at 10°C but not at 5°C, indicating that MT synthesis is temperature dependent and temperature is an important factor affecting toxicity of Cd in N. lapillus. Activity of dogwhelks and oxygen carrying capacity of the haemolymph, were significantly reduced as a result of Cd-exposure at 10°C. In addition, mucus secretion and necrotic cells were observed on the gill surface of Cd-exposed individuals. Therefore, reduction in MO2 may be directly linked to Cd-induced mucus production, structural damage to gills and reduction in oxygen carrying capacity of haemocyanin. However, metabolic depression, including low MO2 and activity, in Cd-exposed N. lapillus may be a strategy to: (i) minimize the uptake and toxicity of Cd; and (ii) minimize energy expenditure to spare energy reserves for detoxification (e.g. MT synthesis) and maintenance (e.g. repair of cellular damage). The results are discussed with reference to the use of MT and glycogen as biomarkers for metal exposure and toxicity in marine molluscs.

This study quantifies the prevalence, abundance, and spatial distribution of epibiotic molluscs on six common neogastropod species in sandy bottoms, Hexaplex nigritus, Chicoreus regius, C. erythrostomus, C. brassica, Vasum caestus and Pleuropoca princeps. A total of 1478 epibiont specimens belonging to 74 mollusc species were examined. The most of epibiotic species were typical of hard-bottoms, but a few species were typical of soft-bottoms. The results indicate H. nigritus is significantly more fouled than the other five species. This can be due to a greater availability of small hollows and a strongly ornamented shell in this species. The spatial distribution of epibionts on the neogastropod shells varied significantly among the different areas into which the shell was subdivided for this study. Fifteen sedentary epibiotic species dominated on all host shells. The costs and benefits of epibiosis are reviewed and the epibiont/host relationship appears to be principally beneficial to epibionts, without a clear benefit for hosts.

The diet of the spider crab, Maja squinado, was studied in the rocky subtidal areas of the Ría de Arousa (Galicia, north-west Spain), by analysing the gut contents of crabs caught in the summer and winter of 1992. The highly diverse diet was made up primarily of macroalgae and benthic invertebrates that were either sessile or had little mobility. The most important prey were the seaweeds Laminariaceae (43% of the frequency of occurrence and 15% of the food dry weight), Corallina spp. (38% and 3%), molluscs [the chiton Acanthochitona crinitus (15% and 1%), the gastropods Bittium sp. (30% and 2%), Trochiidae and others and the bivalve Mytilus sp. (32% and 12%)], echinoderms [the holothurian Aslia lefevrei (32% and 18%) and the echinoid Paracentrotus lividus (16% and 7%)] and solitary ascidians (18% and 6%). The variability in diet composition was determined by the season (Laminariaceae, Corallina spp., P. lividus, Mytilus sp., gastropods and chitons appeared in greater frequency in winter, while the solitary ascidians and A. lefevrei were consumed to a greater extent in summer) in addition to sexual maturity (prey such as Bittium sp. or Trochiidae were more common in juveniles). Moreover, the changes in the food consumption rate were linked primarily to the moult stage. Feeding activity plummeted during the phases immediately preceding and following ecdysis (stages D0–D3–4 and A), and the diet was less diverse during these phases. No feeding differences were found that could be linked to sex. The composition of the diet of Maja squinado appears to be determined by the seasonal abundance of the different prey in subtidal rocky areas and by their availability (depending on their behavioural and anatomical characteristics, mainly mobility and the presence of hard external structures). Moreover, life history factors have little importance in the variability of the diet composition and only the moult cycle has a considerable effect on feeding rate.

The taxonomy of Magellanic and Antarctic cadlinids has been for many years in extreme disorder, and the species were not reliably identifiable. Recent collections in Chile and Argentina, mainly by SCUBA, and re-examination of type material provided data for a comprehensive revision. The present study gives new morphological information on all southern species, both by scanning electron microscope examinations of cuticular structures and detailed microanatomical investigation of the genitalia. The high Antarctic Cadlina affinis does not possess an aberrant androdiaulic genital system but, as all other doridoidean nudibranchs, a triaulic system with a separate vagina and nidamental duct. The vaginal duct is short and leaves the vagina distally, distinguishing this species from other known cadlinids. The genitalia of the holotype of C. kerguelensis from Kerguelen Island have been re-examined. In contrast to previous assumptions, it is not conspecific with cadlinids from South Georgia and the Magellanic region because of clear differences in the genital system. The south-western Atlantic C. magellanica is redescribed and considered to be conspecific with the holotype of C. falklandica from the Falklands. A specimen previously assigned to C. falklandica from South Georgia, however, differs from other southern cadlinids due to genital features and is redescribed as C. georgiensis sp. nov. The Argentinian species C. laevigata and C. berghi, cannot be clearly distinguished from C. sparsa, of which a lectotype has been designated and, therefore, are regarded as junior synonyms. Five Cadlina species from the Southern Ocean are regarded to be valid, and their biogeography is briefly discussed.

The caridean shrimp Rimicaris exoculata, Chorocaris chacei and Mirocaris fortunata, together with bathymodiolid mussels, dominate the vent fauna along the Mid-Atlantic Ridge. Vent shrimp show the characteristic reproductive patterns of caridean decapods. The gonads are paired organs overlying the digestive gland under the carapace. In the ovaries, the oogonia (∼20-30 μm diameter) proliferate in the germinal epithelium at the periphery of the gonad, developing into previtellogenic oocytes. The previtellogenic oocytes grow to 70-100 μm before undergoing vitellogenesis. The maximum size for mature oocytes ranged between 200 and 500 μm depending on the species and the sample. The oocyte size–frequency data show no evidence of synchrony in oogenesis at population level for any of the species studied. Mirocaris fortunata is the only species where gravid females are commonly collected. The brood is carried on the pleopods, and the number of eggs per female ranges from 25 to 503, with a mean egg length of 0.79±0.14 mm. There is a positive correlation between fecundity and body size, characteristic of crustaceans. One ovigerous C. chacei and two R.exoculata have been studied. The former was carrying 2510 eggs and the later 988 small eggs in an early stage of development. The fecundity of M. fortunata, C. chacei and R. exoculata is significantly higher than that of species from the Acanthephyra group collected in the north-east Atlantic.

Annual gametogenic cycle in ocean quahog, Arctica islandica, was investigated using specimens collected regularly from a near shore population in north-western Iceland from December 1997 to November 1998. Gonads from 450 adult quahogs with shell length ranging from 65 to 106 mm were examined after being prepared by standard histological techniques. Observed gametogenic progression was categorized by five phases: (EA) early active; (LA) late active; (R) ripe; (PS) partially spent; (S) spent. All phases of the gametogenic cycle were present in the samples all the year around except in May and June when no spent individuals were seen, and in June and July when no individuals in the early active phase were observed. Morphologically ripe specimens predominated in the samples from May until August when partially spawned individuals dominated the population and did so until February. Spawning activity as inferred from the histological examination appears to be all the year around but most intense from June until August.

The present study evaluated shell utilization and preference of two sympatric hermit crab species, Calcinus tibicen and Clibanarius antillensis, from Ilha Galheta de Dentro, Vitória Bay, south-eastern Brazil. Distribution of individuals and use and availability of shells were estimated in the field, where micro-habitat and shell partitioning were demonstrated between the two species of crabs. Calcinus occurred in higher numbers in the infralittoral fringe and shallow subtidal, while Clibanarius was found mainly in the midlittoral zone. The crabs used shells of different architectures and sizes. Calcinus used mainly globose and low spired shells (Tegula viridula and Cymatium parthenopeum), while Clibanarius utilized predominantly the elongated and high spired ones (mainly Cerithium atratum). Clibanarius used shells with smaller volume, weight, and aperture. Free access experiments were conducted in the laboratory and showed that Calcinus and Clibanarius had a high satisfaction rate, i.e. only 50% of the crabs exchanged their shells. From those that exchanged, they chose shells with higher internal volume than that used in the field, while shell weight did not present any increase. Clibanarius was found in shells closer to the preferred ones and in a very different proportion from shell availability, contrasting to Calcinus, which followed shell availability instead of their preferences. Shell internal volume was more important as a choice factor than the weight for both hermit crab species, showing that crabs optimized shell volume in relation to shell weight in the free access experiments.

The genetic structure of mussel recruits on a rocky shore in Nova Scotia was measured after a rare ice-scouring event which completely removed the intertidal community. Genotype frequencies were measured at three enzyme loci, phosphoglucose mutase (PGM), aminopeptidase-I (product of the leucine aminopeptidase (LAP) locus), and mannose phosphate isomerase (MPI), using cellulose acetate gel electrophoresis. The developing mussel assemblage was a mixture of Mytilus trossulus, M. edulis and their hybrids, with a greater proportion of the former species. Mussel settlers were collected for two years to examine whether genetic heterogeneity existed within and between cohorts of settlers. Settlement of mussels of both species began in April or May and continued into January. Temporal genetic heterogeneity was observed among groups of settlers, resulting from both variations in the relative proportions of the two species and from genetic heterogeneity within M. trossulus. Allele frequencies of mussel cohorts were followed from settlement to ten months post-settlement to investigate the possibility of species-specific selection and of genotype-specific selection within M. trossulus. Temporal genetic heterogeneity primarily was attributed to changes in the proportions of each species, indicating that post-settlement processes were species-specific. Early post-settlement changes were inconsistent, but later changes were clearly directional, resulting in decreased proportions of M. edulis in larger mussels in both years. There was some evidence of genotype-specific post-settlement mortality within M. trossulus, particularly during the early post-settlement period. Our results indicate that temporally variable settlement patterns and post-settlement selection interacted to produce temporal genetic heterogeneity in this mussel assemblage.

Comparative morphology of the cement delivery apparatus of three lepadomorph barnacles indicates that the lepadid Lepas anatifera is unable to relocate voluntarily, whereas the two scalpellids Pollicipes pollicipes and Capitulum mitella can. Mean relocation speeds of up to 50 μm d−1 were measured for both scalpellids, which are probably underestimates of maximal rates given the absence of a directed stimulus. In the laboratory neither gravity nor unidirectional flow proved effective stimuli in directing scalpellid relocation. The two scalpellid species use quite different mechanisms to effect relocation at a leading edge of the base, although both slough basal material at the trailing edge. It is suggested that basal growth effectively accounts for the mobility of P. pollicipes but C. mitella is likely to employ muscular activity.