Population structure of the important commercial brown shrimp, Crangon crangon, was investigated in samples from five UK sites using a multidisciplinary approach based on morphometrics, allozyme electrophoresis and amplified fragment length polymorphism (AFLP). Multivariate analysis of the morphometric data revealed variation in the tail shape of C. crangon from Wansbeck (north-east England), which was found to have longer inner uropod and telson lengths in comparison with all other sites. Linear discriminant analysis was also able to place 86% of the Wansbeck individuals in the correct group. Crangon crangon were screened at two allozyme loci (Gpi and Pgm) revealing higher levels of polymorphism at both loci than previously reported. Allozyme allele frequencies showed evidence of population subdivision between east and west coast UK sites (FST=0.011). Data from three AFLP loci (Cra47, Cra56 and Cra70) confirmed population differentiation (FST=0.083) and combined allozyme and AFLP genetic data identified C. crangon from Wansbeck as different from all other sites. Random genetic drift and selection in populations with restricted gene flow are likely to be the main causes of the differentiation observed. The results do not support an earlier report of six distinct populations based solely on morphometric analysis.

Burrow wall sediment (BWS) and chamber debris (CD) of Pestarella tyrrhena burrows were isolated and compared to surrounding sediments differentiated into surface sediment (SS), deep ambient sediment (DAS) and embedded ambient organic debris (EAD). The focus was on the meiofauna community along with granulometric characteristics including organic content (OC) and bacterial abundances.

Clear trends were found for all parameters: the shrimp significantly increased OC within its burrow and affected grain size distributions. The oxidized burrow walls were highly consolidated, consisted of poorly sorted sediment enriched with silt and clay, and contained small particles of macrophyte debris, while coarse inorganic and organic particles >500 μm were concentrated in the CD. Bacterial abundances (epifluorescence microscopy direct counts, SYBR Gold staining) were positively correlated with OC and were significantly higher in BWS than in SS or DAS. Nematode numbers were elevated three-fold and foraminiferal densities by two orders of magnitude in BWS versus non-burrow sediments. Among the anoxic sediments (DAS, EAD, CD) meiofauna densities in CD were highest. Nematode community analysis (PCA, CANOCO) revealed considerable differences between BWS and SS. The BWS harboured more taxa and was dominated by deposit feeders, while in SS epistrate feeders prevailed.

These effects on different levels demonstrate the ability of P. tyrrhena to create a specific microenvironment within the burrow. The burrow walls were most influenced by the shrimp's activity, which corresponds to their nutritional role.

The two zoeal and megalopal stages of Porcellana cancrisocialis are described and illustrated from laboratory-reared larvae. At an average temperature of 25°C, Zoea I of P. cancrisocialis lasted seven days before moulting to Zoea II which, in turn, lasted eight days to reach the megalopa. Larval features of P. cancrisocialis are compared with those of other species of Porcellana. Porcellana cancrisocialis exhibits similar but distinguishable features from those observed in Porcellana sigsbeiana and Porcellana platycheles. This species resembles P. sigsbeiana more than P. platycheles in the setation and aesthetasc pattern of Zoea I and II, but the relationships of these three species are not clear.

The present work describes the complete larval development of Mithraculus sculptus (two zoeal stages, the megalopa) and the first crab instar from laboratory cultured material. The larval morphology is compared with other descriptions currently available for the Mithrax–Mithraculus complex: Mithraculus coryphe, M. forceps, Mithrax hispidus, M. pleuracanthus, M. spinosissimus and M. verrucosus. Although the different species of the Mithrax–Mithraculus complex display uniform morphological characters, the first zoeal stage of M. sculptus differs from other species in the setal meristics of the carapace and the number of aesthetascs of the antennule. The second zoeal stage differs in the number of aesthetascs of the antennule and the number of setae in the distal margin of the coxal endite of the maxillule. The megalopa of M. sculptus can be distinguished by the presence of 3–4 aesthetascs and a simple seta in the distal segment of the antennule. The morphological differences between the larvae from the genus Mithrax and Mithraculus are insufficient to support the separation of the two genera using adult morphology. Future studies should address in detail setal meristics.

Munida subrugosa and M. gregaria are very abundant in the southern hemisphere, especially off New Zealand and South America. The specific identity of both species is still controversial and accurate identification is needed for conservation or ecological purposes. In this study we used univariate and multivariate methods to determine the morphological differences between both species/morphs. Analyses of covariance of ten morphological variables regressed individually on the carapace length demonstrated that the carapace (including rostrum) and eyestalks (EL) were longer, and the anterior carapace (ACW), the rostrum basis (RBW), and dactylus (DaW) and propodus (PW) of the third maxilliped were wider in M. gregaria than in M. subrugosa. In contrast, the carapace, mandible and eyestalk were wider and the rostrum was longer in M. subrugosa compared to M. gregaria. A stepwise discriminant analysis found that five body measurements namely DaW, EL, PW, RBW and ACW, were useful to discriminate between both species/morphs. The difference between the two discriminant functions provides an objective decision rule for the classification of both species/morphs. We also present the linear relationships of wet and dry masses on size, for use in biomass estimations of Munida spp. as prey.

The gametogenic cycle of Scrobicularia plana was studied in Mweeloon Bay (Galway, west coast of Ireland) over the periods of February to September 1996 and January to September 1997. Quantitative (reproductive indices and oocytes size) and qualitative (gonad developmental stages) analysis identified a broad annual breeding cycle, with one protracted spawning event occurring from May until September. Early gonad development had begun by January/February. Spawning animals were first recorded at the end of May and continued to mature throughout the summer. The decrease in temperature in September coincided with the end of the spawning season and gonad regression. Although the species is predominantly dioecious, one case of hermaphrodism was recorded. A female to male sex ratio of 1.1:1 was registered. Sexual maturity occurred at a shell length greater than 20 mm; the smallest individual undergoing sexual development had a shell length of 22.4 mm. The timing of the reproductive cycle in S. plana at Mweeloon Bay is in broad agreement with previous findings on the species carried out in northern latitudes.

An analytical method for the simultaneous determination of five booster biocides (Sea-Nine 211, Dichlofluanid, Duiron, Irgarol 1051 and Pyrithiones) and degradation product of Irgarol 1051 (M1) in sediment from Vietnam was developed by LC/MS-MS. The recovery rates and relative standard deviation of the booster biocides in the sediment were in the range of 71–108% and 1.5–12%, respectively, and the detection limits were in the range of 0.04–2 μg kg−1 dry. An analytical method for the simultaneous determination of three booster biocides (Sea-Nine 211, Duiron and Irgarol 1051) and M1 in clams was also developed by LC/MS-MS. The recovery rates and relative standard deviations of the booster biocides in the biological samples were in the range of 60–99% and 3.4–6.8%, respectively, and the detection limits were in the range of 0.24–1.1 μg kg−1.

The booster biocides in sediment from the coastal area of northern and central Vietnam were measured using this analytical method. Sea-Nine 211, Dichlofluanid, Duiron, Irgarol 1051, M1 and Pyrithiones were detected in the range of 0.09–1.3 μg kg−1 dry, <0.10–13 μg kg−1 dry, 0.11–3.0 μg kg−1 dry, 0.05–4.0 μg kg−1 dry, <0.1–0.43 μg kg−1 dry and <2–420 μg kg−1 dry, respectively. The detection frequencies of Dichlofluanid, M1 and Pyrithiones were low. The species and levels of detected booster biocides varied between sampling stations.

Irgarol 1051 and its degradation product M1 were not detected in clams.

A field survey to re-assess imposex and tributyltin (TBT) bioaccumulation in the gastropod Nassarius reticulatus over Galicia uncovered three populations of the invasive species Cyclope neritea, all showing some advanced imposex. One female was found to carry a mass of aborted egg capsules. The TBT pollution, now decreasing in the area, is the most likely explanation for these reproductive anomalies, and it may bear some relationship to the described population dynamics of C. neritea.

The haemogram (blood cells concentration, number and proportions of haemocyte morphotypes) of the common periwinkle, Littorina littorea, was studied in terms of its individual variations and seasonal dynamics. No granular blood cells were found. Three morphotypes of hyalinocytes were observed in the haemolymph of L. littorea and are described at both light and electron microscopy levels: juvenile round cells, intermediate cells and large mature haemocytes. The nucleoplasmic ratio, nucleus shape and location, number and size of glycogen deposits were the main characteristics used to discriminate between the haemocyte morphotypes. The enzyme cytochemistry and lectin binding studies did not identify additional haemocyte morphotypes. The experiments on BrdU incorporation showed that haemocyte population renewal occurred due to the proliferation of only one cell type, namely blast cells, which were morphologically similar to juvenile round cells. The three-month dynamics of the periwinkle haemogram and haemoblast proliferative activity are described. The blood cell concentration reached maximum values twice per summer season—in June and August, with the haemocyte proliferation activity being the highest in June. The percentage of mature haemocytes increased during the season, simultaneously intermediate cells demonstrated a decrease in number by the end of summer, with the population of juvenile cells being nearby constant. The method of haemogram analysis is positioned as a powerful technique having good potential in eco-toxicological, parasitological and immunobiological studies.

The examination of five females of the deep-benthic octopus Graneledone pacifica—a large-egged species: mature ovarian egg length >20 mm—showed that their developing oocyte size-distribution was normal in two specimens at an early maturation stage (largest oocyte length=3 mm), bimodal in two specimens at a more advanced stage (largest oocyte length=6 and 8 mm, respectively), three-modal in the farthest advanced stage specimen (largest oocyte length=14 mm). According to the literature, the simultaneous occurrence of oocyte cohorts at different oogenic stages, including a distinct cohort of oocytes at an advanced maturing stage in one specimen, suggests that G. pacifica is a multiple spawner.

In this study, an overview of the current species composition of ophiuroids off Helgoland, German Bight (North Sea) is given. In addition, abundance and distribution of ophiuroids on different types of soft bottom sediments taken by van Veen grab samples around Helgoland were recorded. The literature was reviewed in order to outline the diversity of ophiuroid species over the past 130 years in the inner German Bight. In the historical literature, quantitative references often apply to verbal descriptions and thus make comparisons to modern data and assessment of possible changes in abundance rather subjective.

In total, six ophiuroid species were identified off Helgoland: Acrocnida brachiata, Amphiura filiformis, Amphipholis squamata, Ophiothrix fragilis, Ophiura albida and Ophiura ophiura. The species found in this study had also been reported by previous investigators and are regarded as ‘common’ species in the German Bight. Occasional findings in this area refer to Amphiura chiajei, Ophiopholis aculeata, Ophiocten affinis and Ophiura sarsi, which are regarded here as ‘rare’ species. These findings, however, do not indicate sustainable changes in the species diversity over time.

Apart from Acrocnida brachiata, a newcomer in the 1970s, findings of the common species mentioned above can be dated back to 1875. Therefore, a fairly stable composition of brittle stars is represented in the inner German Bight during the past 130 years.

Skeletal development of Ophiactis resiliens and Amphiura constricta was examined to determine characters that could be used to identify the juveniles of these species, which co-occur in algal turf habitat. Juvenile O. resiliens recruit to turf after a planktonic larval stage while A. constricta recruit through release from brooding adults. Skeletal development in O. resiliens and A. constricta is typical of most ophiuroids with diagnostic adult characters taking some time to appear. The main characters that can be used to distinguish the two species from an early stage are the number and arrangement of the oral papillae and the presence of disc spines. In O. resiliens diagnostic adult skeletal characters developed at 1.5 mm disc diameter. In A. constricta most identifying adult characters were evident at 700 μm disc diameter. Identification of juvenile O. resiliens is assisted by the presence of disc spines and thorny arm spines, features that disappear as the juveniles grow. Juvenile A. constricta did not develop disc spines or thorns on the arm spines.

The hindgut caecum of the deposit-feeding echinoid Echinocardium cordatum harbours a symbiotic bacterial microflora, organized into layered mats around detrital particles owing to the proliferation of filamentous bacteria. The bacterial community was analysed using 16S rRNA gene analysis and fluorescence in situ hybridization. The purpose was to characterize its biodiversity and to identify its predominant members. The majority of the 16S sequences belong to the δ-Proteobacteria (61.5%), the Bacteroidetes and the Firmicutes constitute the two other main bacterial groups (respectively 23.1% and 15.4%). A total of 41% of the δ-Proteobacteria clones isolated belong to a bacterium of the genus Desulfonema for which a specific oligonucleotide probe was designed, enabling identification of its distribution in the nodules.

The gonadal development and morphometry of Appendicularia sicula (Appendicularia: Fritillariidae) were studied by means of histological sections and from the measurement of several characters. Based on morphometric measurements, the ingestion and clearance rates and the percentages of consumed chlorophyll-a were also estimated. The gonadal development is similar to that of Fritillaria pellucida. A small dorsal ovotestis, which originates ovary and testicle, shows large somatic nuclei inside. In the ovary these somatic nuclei are surrounded by a single layer of germ cells nuclei, whereas in the testicle they are found between the small nuclei of the germ cells. As the development proceeds, the large somatic nuclei are resorbed in both gonads, and the testicle finally envelopes the ovary posteriorly. After spermatozoids emission, the rectum is shown occupying most of the body volume. The length of the rectum shows a positive allometric growth in respect to the length of the trunk, which can be ascribed to its continuous accumulation of matter due to the lack of an anus. The relationship obtained between trunk length (TL, μm) and dry weight (DW, μg) was DW=2.24×10−11 TL4.098. Applying this equation, a two-fold increase in length would correspond to a 42-fold weight increase. For specimens with an advanced sexual maturity (400–450 μm TL), we estimated a mean autotrophic ingestion rate of 0.17 μg C ind−1 d−1 and a mean clearance rate of 5.01 ml ind−1 d−1. The percentage of total chlorophyll-a consumed by the A. sicula population was 5.13%. This value is similar to those reported for other appendicularian species in different temperate seas.

Temporal variation in a temperate cryptobenthic fish assemblage at the Arrábida Marine Park (Portugal) was assessed by visual surveys during 2002 and 2003. A total of 9596 fish from 11 families and 30 species was recorded. There were no changes in structure or density at the assemblage level between years, whereas diversity changed significantly due to a higher number of abundant species in the second year. A similar seasonal trend was found between years, with a significant overall density increase in autumn. This is partially explained by the arrival of new recruits of some of the most abundant species in the assemblage. Assemblage diversity and structure also changed across seasons. A group of species encompassing Gobius xanthocephalus, Tripterygion delaisi, Parablennius pilicornis, Gobius paganellus, Lepadogaster candollii and Lepadogaster spp. were analysed in detail. The temporal patterns of two of the most abundant species, G. xanthocephalus and T. delaisi, mimicked the overall temporal patterns of the assemblage. We suggest that the inter-annual stability in density of this subtidal fish assemblage may be similar to what has been reported for the intertidal and that strong post-settlement processes are probably shaping this assemblage.

The cyclone Erica (Class 5) hit the South Lagoon Marine Park of New Caledonia on 14 March 2003, in the midst of a survey conducted on coral reef fish and habitat of Larégnère and Crouy reefs. Such perturbation was exceptional for the area. Nine stations had already been sampled (8–11 March 2003) when the cyclone hit the reefs. These stations were sampled again just after the cyclone (23 March–15 April 2003) and 20 months later (14–16 November 2004). Erica had a significant initial impact on habitat characteristics. The fragile coral forms cover (branching, tubular and foliose) decreased significantly, resulting in a loss of habitat for the fish communities. Species richness and biomass of the commercial reef fish and the Chaetodontidae decreased just after Erica, but not the density. The species assemblage was modified on the stations with the lowest remaining live coral cover. The loss of shelter modified the behaviour of potential prey, which constituted unusual shoals and attracted predators. Twenty months after Erica, the habitat had not recovered and the broken coral colonies were transformed into rubble or colonized by algae. The nature of the mid-term impact on the fish communities was different and more significant than the initial impact. Species richness per station, density and biomass were significantly lower than before and just after Erica. This pattern was confirmed for all the main families, with the exception of Acanthuridae. A different fish assemblage was observed on all stations 20 months after Erica. Herbivorous species and benthic macro-invertebrate feeders associated with rubble replaced the coral associated species that characterized the assemblages before the cyclone. When a Class 5 cyclone affects an area where perturbations of such intensity are uncommon, its impact is immediate and the mid-term consequences are even more significant. A complete modification of the structure of the habitat and the fish assemblages is observed. The consecutive recovery should be a long process.

Here we provide baseline data on the distribution and abundance of Mola mola within the Irish and Celtic Seas, made during aerial surveys from June to October during 2003–2005. These data were considered in conjunction with concurrent observations of three potential jellyfish prey species found throughout the region: Rhizostoma octopus, Chrysaora hysoscella and Cyanea capillata. A total area of 7850 km2 was surveyed over the three years with an observed abundance of 68 sunfish giving a density of 0.98 ind/100 km2. Although modest, these findings highlight that the species is more common than once thought around Britain and Ireland and an order of magnitude greater than the other apex jellyfish predator found in the region, the leatherback turtle (Dermochelys coriacea). Furthermore, the distribution of sunfish sightings was inconsistent with the extensive aggregations of Rhizostoma octopus found throughout the study area. The modelled distributions of predator–prey co-occurrence (using data for all three jellyfish species) was less than the observed co-occurrence with the implication that neither jellyfish nor sunfish were randomly distributed but co-occurred more in the same areas than expected by chance. Finally, observed sunfish were typically small (∼1 m or less) and seen to either bask or actively swim at the surface.

Spawning temperature preferences for sardine (Sardina pilchardus) in the eastern North Atlantic were determined from egg survey data. These were compared with climatological temperature cycles (1986–2002) derived from satellite observations, by geographical region, to predict spawning seasons. Optimum spawning temperatures were determined as 14.0–15.0°C from the English Channel to Portugal and 16.0–18.0°C for all north-west African regions. Spawning seasons were closely related to the general latitudinal trend of the annual temperature cycle, with modification by upwelling in the western Iberian and north-west African regions. Some differences between temperature-based spawning season predictions and field observations were related to variations in seasonal plankton production. Correlations in the annual time-series of favourable spawning temperatures suggested relatively strong linkages between the southern areas from Portugal to Senegal. There was no consistent relationship between annual variations in extent of temperature-predicted spawning seasons and observed field abundance of eggs.

Through a series of ichthyoplankton surveys carried out off central Chile, we characterize the offshore spawning and coastal nursery ground of the bigeye flounder Hippoglossina macrops. Eggs were collected in higher abundances over the continental shelf during late winter, over the shelf-break in mid spring, and at the continental slope in late summer, showing a seasonal depth gradient in spawning. No significant spawning was detected nearshore (less than 8 km offshore). Field data suggest a longitudinal progression from offshore to onshore of larval stages from preflexion to transformation stage. Finally, vertically stratified samples showed that eggs and larvae were present mainly in the upper 100 m. We discuss the potential onshore transport of early life stages of H. macrops through the compensatory flow of Equatorial Subsurface Waters that balances the surface offshore transport in the Ekman layer during upwelling events. Additionally, larval development from yolk-sac to transformation stage is briefly described.

Here we report on a previously undocumented facultative symbiosis involving the wrasses Labroides dimidiatus and Thallasoma amblycephalum living in association with two species of sea anemones, on coral reefs in the north-western Pacific. By SCUBA diving we observed juvenile L. dimidiatus occurring in Entacmaea quadricolor (solitary type) cleaning the anemonefish Amphiprion frenatus and in Heteractis magnifica cleaning the anemonefish Dascyllus trimaculatus. Thallasoma amblycephalum co-existed in H. magnifica with the anemonefish D. trimaculatus, A. ocellaris and L. dimidiatus.