Ucides cordatus is a semi-terrestrial crab and key species endemic to mangrove areas of eastern Americas. In North-eastern Brazil this crab holds a major socio-economic function for artisanal fisheries, as in the São Francisco River Estuary (10°30′27″S 36°23′45″W). Nevertheless, decreases in this species’ stock have been reported since 2000, requiring assessments of the crab population for conservation and management purposes. This study aims at assessing the population status and the fishery potential of this species in the mangroves of this estuary and suggests strategies for its fishery and conservation, according to the guidelines of the National Management Plan for U. cordatus Sustainable Use. Six different sites established in 30 km2 of mangroves were sampled, with the density of U. cordatus burrows estimated to evaluate the population structure using the measure of burrow diameters. Results show that the crab mean burrow size was 56.82 (±12.2) mm and that the medium-size crabs (40–70 mm) are the most abundant. The total mean crab density was 1.2 crabs m−2, from which the density of crabs in commercial size (0.85 ± 0.55 crabs m−2) was significantly higher than those in non-commercial size (0.35 ± 0.21 burrow m−2). These mangroves showed a high potential for the crab fishery, with an immediate extractive potential (IEP) of 71.2% and future extractive potential (FEP) of 28.8%. Nevertheless, a lower crab density, probably due to high crab mortality, mangrove deforestation for shrimp farming and high fishery pressure, is a limiting factor for local fishery. We conclude that mangrove areas more appropriate for U. cordatus fishery (extractive areas) show higher mean crab size, IEP and density of commercial crabs, wherein a fixed exploitation rate or/and a fixed escapement rule should be considered. Exclusion areas, intended for the conservation, show lower values of these population parameters and higher FEP, wherein the fishery should be prohibited. These management strategies should also be considered in other Brazilian mangrove areas showing similar crab population structure, thus contributing to the National Management Plan for U. cordatus Sustainable Use.

The increasing human impact at shallow depths may be affecting the Mediterranean endemic coral Astroides calycularis irreversibly. Therefore, management tools need to be developed for use in its conservation. The main aim of this study was to test a reliable attachment methodology for restoring sites where the species has been affected by human activities. We chose an attachment technique using a marine quick-action epoxy resin, completing three treatments (control, transplanted and translocated colonies) in two sites with different hydrodynamic conditions. Control colonies were undisturbed colonies that were not manipulated; translocation colonies were dislodged and reattached in the same place; and transplantation colonies were dislodged and attached in a different area. Translocated colonies showed a higher survival than transplanted ones, and survival was also higher in environments with more hydrodynamism. Regarding growth, Analysis of Variance (ANOVA) did not show significant differences among treatments, but significant differences between areas with different hydrodynamic conditions were noted. This study confirms that it is possible to transplant or translocate colonies of this coral with the technique proposed here, which could be used in future management plans for areas impacted by humans.

The present study enhances knowledge of the biodiversity of diatoms in Chuuk, Micronesia following our 2018 study on the seaweed-associated diatoms. We collected planktonic samples of diatoms from five sites of reef flats using a 20 μm mesh net, and two samples of seaweeds with epiphytes by hand from an islet on the barrier reef. In addition, the seaweed-associated diatoms from our 2018 study were analysed using scanning electron microscopy. A total of 109 diatom taxa are documented in the present study. Of these, 70 species were from net samples, and 39 species from the seaweed-associated diatoms. Thirty-one species are newly recorded from Micronesian waters. Most taxa are benthic or tychoplanktonic; euplanktonic diatoms were rare. The occurrence of benthic diatoms from the water column might be related to the Chuuk environmental conditions which include shallow water, strong light intensity and high grazing pressure, to which benthic diatoms seem to be able to better adapt than planktonic diatoms.

Samples of branched and unbranched forms of the marine thecate hydroid Aglaophenia pluma (L.) (Hydrozoa, Plumulariidae) were collected from the western and eastern sides respectively of Carmarthen Bay (South Wales). Tissue from various colonies of each type was cleaned of epifauna and homogenized for horizontal starch gel electrophoresis. Useful results were obtained for 14 enzyme loci coding for a total of 11 different enzymes. Eleven of the 14 loci showed no common allele between the branched and unbranched forms. Nei's genetic identity was estimated as 0·18 and genetic distance as 1·7. Such a high level of genetic differentiation between morphotypes provides strong evidence that the populations are reproductively isolated and should be regarded as distinct species. It is suggested that the branched form may be Aglaophenia parvula Bale, a species until recently better known from the southern hemisphere. Morphological distinctions between the two species are discussed.

The morphology of the cells during oogenesis in Amiantis umbonella (Mollusca: Bivalvia) was investigated from collections made between November 1997 and January 1999. Each stage is described and prominent features noted. A unique arrangement of auxiliary cells around the oocyte is described.

The sediment surface within the Osbornia belt of a mangal on Pulau Hoga, Tukang Besi Islands, Sulawesi, Indonesia, is dominated inter alia by deposit-feeding gastropod molluscs at a mean density of some 230 ind m−2 although, unusually, species of Cerithidea do not occur. Densities of the two most numerous species, the potamidid mud-whelk Terebralia sulcata and the Cerithidea-like cerithiid mud-creeper Cerithium coralium, are inversely correlated, although the species occurred together in 42% of quadrat samples. Within and beyond the normal range of field densities of each species (C. coralium mean 153 m−2; T. sulcata mean 75 m−2) there was no evidence of intraspecific depression of feeding rate, as assessed by the production of faecal pellets, although this was significantly reduced in the occasional very high density aggregations of C. coralium (>1100 m−2). The presence of the larger T. sulcata did appear to have a strong inhibitory effect on feeding in C. coralium; the converse, however, could not be demonstrated. Abundances of Terebralia palustris and C. coralium were also inversely correlated where the two co-occurred.

Two species of wrasse, Ctenolabrus rupestris (L.) and Crenilabrus melops (L.) were experimentally infected with the digenean Proctoeces subtenuis (Linton) collected from Scrobicularia plana (da Costa). The fishes were killed 1-24 days after infection, and the parasite population of their guts examined. About 20 % of the introduced parasites survived for 2-3 days, but the degree of infection decreased with time, the smallest specimens surviving longest. No significant differences were found between parasites from invertebrate and experimental vertebrate hosts.

P. major Yamaguti, 1934, and P. insolitus (Nicoll, 1915) are declared synonymous with P. subtenuis (Linton, 1907

The bearing of these results on the life cycle of P. subtenuis is discussed

The regeneration of cirri was followed in two common intertidal barnacle species, following non-lethal predation by an intertidal teleost. While >50% of damaged Semibalanus balanoides individuals showed some degree of cirral re-growth within 16 days, this level of regeneration was not reached in Chthamalus montagui until 32 days after removal of the cirri. Full re-growth of cirri required at least two moults in both species.

Effects of external cation concentrations on larval metamorphosis in the ascidian, Halocynthia roretzi were examined. Metamorphosis (tail resorption) was induced by 20 mM and 50 mM K+ but, interestingly, was suppressed by 30 mM K+. Low concentrations of Ca2+ (1–5 mM) induced metamorphosis, while high concentrations did not, in contrast to findings in other invertebrates. Moreover, BAPTA-AM, an intracellular Ca2+ chelator, induced metamorphosis. This suggests that a decrease in intracellular Ca2+ of certain cells initiates larval metamorphosis in H. roretzi.

The dry weight and organic carbon content of eggs and components of Clyde spring herring eggs were measured at intervals during their development. Comparison with previously published data suggests that an increase has occurred in the weight of these eggs over the past thirty years. It is clear that only a small proportion of the material deposited in the form of herring spawn actually remains attached to the substratum when the larvae hatch and so is available for potential integration into the benthic food web. This was confirmed by the determination at intervals over two years of the organic carbon content of the gravel sediments on spawning grounds of the Clyde spring herring. Although the deposition of herring spawn resulted in an immediate marked increase in the carbon content of the spawning ground sediments, carbon levels quickly returned to pre-spawning levels and there was no evidence of any permanent or long lasting increase. This held true when the spawn died and decayed in situ and even when it was mixed into the sediment by wave action. The rapid decrease in carbon levels is attributed to the strong water movements which frequently occur over the spawning grounds.

Epimeriidae is an amphipod family with a worldwide distribution. A new species was found from the Tasman Sea at a depth of 12 m depth and described in detail. Epimeria norfanzi sp. nov. can be distinguished from other Epimeria by a combination of the following characters: coxal plates 1–3 ventrally rounded; protrusion of coxa 5 reaching the distal end of epimeral plate 2; and urosomite 1 with dorsal keel, telson not cleft. This new species increases the number of Pacific Epimeria species to ten. A brief synopsis of the Pacific Epimeria species is given and a key provided.

The diversity and distribution of polychaete species under the families Nereididae, Syllidae and Eunicidae in sub-tidal fouling assemblage was studied by submerging wood as test substratum. Wooden panels were fitted onto a raft and submerged in Kudankulam coastal waters (south east coast of India) in pre-monsoon, monsoon and post-monsoon seasons from May 2003 to July 2005. Panels (in replicate) were retrieved from the raft at 15-day intervals. A total of 24 polychaete species belonging to the three families were identified from the test panels. Perinereis cultrifera, Platynereis dumerilii, Syllis variegata, Syllis truncata, and Eunice australis were the dominant species observed on the test panels. The abundance of major polychaete group was varied considerably between the panel series submerged in May 2003 (post-monsoon), November 2003 (monsoon) and July 2004 (pre-monsoon). The major difference in the polychaete community structure was the low abundance of both nereidids on pre-monsoon season panels and the eunicids on monsoon and post-monsoon season panels.

Sperm ultrastructure in two species of the marine snail family Olividae is examined. Euspermatozoa of both species are composed of a conical, membrane-bound acrosomal vesicle; an axial rod and a basal plate similar in both species; a solid and highly electron-dense nucleus; an elongate midpiece consisting of the axoneme sheathed by helical mitochondrial elements; an elongate glycogen piece; a double electron-dense ring at the junction of the midpiece and glycogen piece; and a free tail region. The slight narrowing in the acrosomal vesicle invagination is situated in different levels between Olivancillaria deshayesiana and Olivancillaria carcellesi. This morphology could be considered as a specific character. The length of the nucleus in O. carcellesi and in O. deshayesiana is shorter than that of other neogastropods, and could be diagnostic at family level.

Relationships between sediment characteristics and the spatial organization of biogenic structures remain poorly understood, albeit important for characterizing bioturbation impacts and small-scale ecological patterns. Using axial tomodensitometry (CT-scan) and core sectioning, we studied the spatial distribution of Alitta virens burrows in sediment cores from two mudflats with different degrees of exposure along the St Lawrence Estuary, Canada. A variety of burrow morphologies was observed at both sites, with most being I-shaped. Most values measured (organic matter content, mean tomographic intensity, the number and diameter of burrow shafts and the percentage of space they occupy per transverse section) covaried with depth. The more sheltered site had higher organic matter and mud contents, and lower average tomographic intensity values. The spatial distribution of burrow shafts also differed between sites, with the more sheltered site having a higher number of burrow shafts and percentage of biogenic space in the upper sediment column, as well as a greater volume of biogenic structures that were connected to the surface (although intra-site variability was great). Along the horizontal plane and at various depths within sediments, burrow shafts were more randomly distributed at the exposed site, compared to a more even, maximal spacing at the sheltered site. In addition to finding differences in burrow organization at two spatial scales, we found significant correlations between tomographic intensity and (1) the number of burrow shafts, (2) biogenic space and (3) organic matter content. CT-scan data, including tomographic intensity, are useful for examining and comparing biogenic structures in sediment cores.

This is a report of the Cœlenterate plankton taken during the cruises of the Evadne in 1925, and investigated at the request of Professor A. D. Peacock. I am indebted to Miss Ann R. Sanderson, B.Sc., for considerable help in the identification of specimens.

The behavioural patterns of humpback whales are known to vary according to the social function of individuals in a group. To identify behavioural patterns related to specific group compositions, we observed events and behavioural states of humpback whales during research cruises in the Abrolhos Bank, Brazil, in the reproductive seasons from 1992 to 2003. We monitored 3022 groups and found a predominance of competitive groups without calves, when compared to competitive groups with calves. A Bayesian network analysis supplied occurrence probabilities for the behaviours analysed, indicating higher probabilities of occurrence for the behavioural patterns designated travelling and socializing. The model, generated from a binomial logistic regression, was able to predict competitive groups in association with the occurrence of the following aggressive behaviours: head-lunging, trumpet and bubblestreams. This study suggests the existence of behavioural patterns associated with specific group compositions and reinforces the concept that there is a clear-cut relation between competitive groups and the occurrence of aggressive behaviours. The preferential association of males to females with high reproductive potential for the following year (i.e. females without a calf) was also identified.

At the time of his death in 1953 Orton had almost completed an extensive study of the biology of the three British species of Patella. Although certain aspects of the investigation were dealt with by collaborators and have already been published (Crewe, 1947 on parasites; Goodwin, 1950 on pigments; Jones, 1948 on ecology) most of the breeding and spawning data have been neither analysed nor published. With the knowledge that Orton's records contained the most complete information on breeding yet compiled for a littoral animal, and that these records had considerable bearing on the question of speciation in Patella, we have attempted to analyse and present those which are most complete.

The Lutrariidae are large lamellibranchs which burrow deeply in bottom-deposits on the shore and in shallow water. The foot is relatively weak, and they live permanently buried 30 cm or so beneath the surface, maintaining connexion with the overlying water through their long siphons, which are united in a common sheath for practically their whole length. The commonest British species, Lutraria lutraria (L.) is found at low-water mark on shores of muddy sand, and offshore its siphons are sometimes taken by the dredge or grab. Another species, L. magna (da Costa) is more local, and appears to inhabit muddy deposits near the mouths of estuaries. It is a southern form, being occasionally found on the south and west coasts of the British Isles, and, like L. lutraria, its range extends southward to the Mediterranean.

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.

Opisthoteuthis hardyi was originally described from a single male specimen caught near Shag Rocks (north-west of South Georgia) and no further specimens have been attributed to this species. During research fishing on the Patagonian slope to the south-east of the Falkland Islands 33 specimens of Opisthoteuthis were caught at depths ranging from 630 to 1391 m. Morphological measurements indicated that these specimens were conspecific to the holotype of O. hardyi. The mitochondrial gene 16S rDNA was sequenced from two of these specimens and compared with a published sequence of the holotype and other Opisthoteuthidae to confirm the morphological data. This extends the geographical and bathymetric range of the species, which spans the Antarctic Polar Front. We also expand the original description, providing details of the digestive system and of the female reproductive system, with preliminary estimates of fecundity.