The long-spined sea urchin Diadema antillarum has been the focus of multiple studies since the mass mortality event in the 1980s. The recovery of this key herbivore in the wider Caribbean is essential for the well-being of coral reefs. This study examined the population density and structure of D. antillarum at seven northern fringing reefs of Puerto Rico between 2011 and 2013. The total mean density of the sea urchins in northern Puerto Rico was 0.9 ±0.3 ind m−2. Densities of D. antillarum significantly differed among sites, but not temporally. Differences in mean sizes were significant among sites and seasons. Areas with higher densities of D. antillarum showed lower cover of non-calcareous algae. Wave exposure was correlated with the abundance of the sea urchin. This study indicates that the observed abundance of D. antillarum has not yet returned to pre-mortality levels. However, densities showed some degree of recovery when compared with previous studies, enabling at least some degree of control on fleshy macroalgae communities. No significant changes in density occurred between 2011 and 2013, and sites with higher densities were generally located in leeward areas. The low relative abundance of small size individuals points towards recruitment limitation as an explanation for the limited recovery of D. antillarum.

This study aimed to assess the influence of growth and reproductive cycle on the meat yield and proximate composition of the banded murex (Hexaplex trunculus) from the Ria Formosa lagoon (Algarve coast, southern Portugal). Samples of the edible portion (all soft-body tissues) were analysed monthly during one year. The average meat yield was 37.9±4.6%, with females containing more edible content (39.1±4.7%) than males (36.8±4.2%). The proximate composition comprised 70.7±1.4% moisture, 20.1±1.2% protein, 1.6±0.3% fat, 3.0±0.3% ash, and 4.6±1.2% carbohydrate, corresponding to an energetic value of 119.2±7.5 kcal/100 g wet weight. The meat yield was influenced by specimen size, increasing significantly during growth. Both meat yield and proximate composition presented seasonal fluctuations related to the reproductive cycle, which coincided mainly with the periods of maturation and spawning of this species in the Ria Formosa. Finally, H. trunculus meat yield and proximate composition were compared with similar information available for other marine gastropods.

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.

The present study describes the species composition and vertical distribution of chitons in tide pools and on exposed rock areas of the intertidal zone of Samara, Guanacaste, Pacific Costa Rica. Nine different species of chitons were recorded, and their densities and sizes were determined using quadrate sampling. Physical (period of emersion, temperature and salinity range) and biotic (presence and diversity of food resources) factors were examined to assess their influence on distribution and abundance of each species. Ischnochiton dispar was the predominant species with densities of up to 200 ind m−2, representing 85.4% of all sampled individuals (N = 4193). The size of I. dispar was positively correlated with the size of the inhabited boulders. Two species (I. dispar and Stenoplax limaciformis) showed segregation in size: I. dispar being negatively and S. limaciformis positively correlated to the distance from the shore. Two of the nine species (Chiton stokesii and Acanthochitona hirundiniformis) occurred mainly on rocky areas outside the tide pools with variable amounts of exposure to air during each tidal cycle. In both species the tide pool specimens were significantly smaller than those collected in the rocky areas. Distribution of all other species was restricted to the tide pools and species had their peak abundance in the zones with more moderate conditions and a higher diversity of algae, resulting in the highest chiton diversity in these areas.

Sulphur-isotopic composition of soft tissues from Bathymodiolusmarisindicus collected from hydrothermal vents in the Indian Ocean was reported. The δ34S values of the soft tissues (+3∼+5‰ vs Cañyon Diablo troilite) were nearly identical to those from the associated hydrothermal fluid and chimney sulphides (+5 to +8‰), but were significantly different from that of the common seawater sulphate (+21‰), which suggested that the endosymbiotic bacteria used sulphide in the fluid as an energy source. Transmission electron microscopic observation of the endosymbionts also suggested that the symbiont is a thioautotroph. Bathymodiolus species, which depend on either sulphide or methane oxidation, or both, have a worldwide distribution. Bathymodiolus marisindicus from the Indian Ocean has a close relationship with congeners in the Pacific Ocean as evidenced by form of symbiosis. Biogeography and migration of the genus Bathymodiolus based on the relevant data are briefly discussed.

Two inshore rocky subtidal sites on the west coast of Scotland (Saulmore Point, Firth of Lorn, 056°27′N 005°24′W and Davy's Rock, Firth of Clyde, 055°46′N 004°53′W) were surveyed for the presence of juvenile (0+) Atlantic cod, Gadus morhua between September 1995 and November 2001. A total of 951 juveniles were recorded at Saulmore Point and 34 at Davy's Rock. At Saulmore Point the abundance was highly seasonal, being observed between June and December only. Juveniles were present in only three out of six survey years, with a maximum abundance of 0·89 individuals m−2 recorded in 1996. Maximum abundance of juveniles at Saulmore Point was negatively correlated with winter seawater temperature, indicating that winter temperatures may be a useful indicator of subsequent juvenile abundance levels in inshore habitats.

Young-of-the-year bass (Dicentrarchus labrax) were sampled from ten Bristol Channel sites during 1996, 1997 and 1998 to investigate whether the pattern of recruitment to south Wales nurseries observed following the ‘Sea Empress’ oil spill in spring 1996 was anomalous. Back-calculated egg fertilization (spawned) dates indicated that early spawning events (February–March) at the Trevose Head spawning area provide recruits to south Bristol Channel nurseries, and that the majority of recruits to south Wales nurseries arise from subsequent spawning events. Recruitment of post-larvae to all nurseries in the Bristol Channel starts in late June–early July. The late recruitment of 0-group bass to all nurseries in 1996 was attributed to lower water temperatures in February and March than in 1997 and 1998, and was not restricted to south Wales. However, 0-group bass were relatively less abundant in 1996 at sites nearest the ‘Sea Empress’ oil spill, suggesting a possible effect of the latter on survival of post-larvae in the nurseries, rather than during the offshore egg and larval stage.

Seven osteological characters of the axial skeleton are studied in the eight species of the genus Pampus. The characters include: pattern of interdigitation of the dorsal- and anal-fin pterygiophores with the neural and haemal spines of the vertebrae, structure of the vertebral column, distribution of the dorsal- and ventral- procurrent caudal-fin rays, distribution of the principal caudal-fin rays and the morphology of the caudal-fin skeleton. All these features appear to be useful in the characterization of the eight species of the genus Pampus. Formulae for the structure of the vertebral column, the dorsal- and anal-fin pterygiophores’ interdigitation with the neural and haemal spines of the vertebrae, distribution of the dorsal and ventral procurrent caudal-fin rays, and distribution of the principal caudal-fin rays were developed. Pampus nozawae was recently considered a synonym of P. argenteus. However, according to the characters used in the present study, this species is notably distinct from P. argenteus.

The following notes are the result partly of an examination of various living specimens at Plymouth in the spring of 1905, and partly of the study of preserved material most kindly placed at my disposal by Mr. E. J. Allen and Mr. W. I. Beaumont, of the Laboratory, Plymouth, Mr. W. E. Hoyle, of the Manchester University Museum, and the Council of the Hancock Museum at Newcastle. I must also express my thanks and obligations to Mr. T. J. Evans, lecturer in Biology at the University of Sheffield, who has prepared for me sections of the smaller specimens and embodied the results in drawings which will add very materially to any value which this paper may have.

The Clyde Sea Area is in many ways an ideal ground for the investigation of the nutrient salts in the bottom deposits. The different lochs present a range of depth of water of from 0 to 200 metres: some parts have strong tidal currents up to five knots, while others are practically unaffected by the tide: some lochs have also been affected by the dumping of sewage and harbour sludge, and the effect of these can be examined. Conditions may also be compared in muds ranging from the loch heads to the almost open sea conditions at Ailsa Craig.

Excavation counts (absolute density), burrow counts and surface active individuals visual counts in a Uca tangeri population were compared. Population density estimated from burrow counts was not significantly different from population density estimated by excavation, but the population density estimated with visual counts was significantly lower than the absolute density. Ovigerous females should be the main cause of these differences because they frequently remain underground, but other groups of crabs are also contributing to this difference. Burrow counting is an accurate and quick non-invasive method for the census of U. tangeri. Other population measures (e.g. sex ratio) are not obtainable by burrow counting and only further understanding of the activity patterns of this species along the tide cycle, moon phase and reproductive season will allow visual counting of surface active individuals to be used as quick, efficient and non-invasive method for crab density and population structure estimation.

Arsenic compounds in aqueous extracts of muscle, liver, kidney, and lung tissue taken from a sperm whale Physeter catodon (Mammalia: Cetacea) beached on a small island near Phuket in the Andaman Sea were determined by high performance liquid chromatography using an inductively coupled plasma mass spectrometer as the arsenic specific detector. The total arsenic concentrations in the tissues (dry mass) were low, ranging from 0·3 μg g−1 for liver and lung, to 1·0 μg g−1 for muscle and 3·0 μg g−1 for kidney. Most of the arsenic (>60%) was extracted from the tissue into water, and the bulk (>80%) of this arsenic was present as arsenobetaine. Dimethylarsinate was present at low levels in all four tissues whereas arsenocholine was detected in kidney, liver and lung, but not in the muscle tissue. Another arsenic containing betaine, trimethylarsoniopropionate, was also present in all four tissues. This is only the second report of trimethylarsoniopropionate as a naturally-occurring arsenic compound.

The shape of foregut lumen in both the pharyngeal and the oesophageal regions has been examined from serial histological sections in 16 species of pycnogonids covering all extant families. Each species has a Y-shaped foregut lumen in transverse section. This result shows that some previous authors misoriented the lumen as inverted Y-shaped. The triradiate Y-shaped foregut lumen has been found among ecdysozoans including tardigrades, onychophorans and scatteringly arthropods. At present, it is not clear whether the Y-shaped state of the characteristic in pycnogonids is convergent or symplesiomorphy with that in tardigrades and onychophorans.

Patterns of in situ fertilization success with respect to high and low tide periods are reported for the intertidal red seaweed Gracilaria gracilis which inhabits rock pools. Cystocarp (zygote) production was experimentally compared at high tide and low tide in both high- and low-shore tide pools at two sites using ten virgin female plants. High- and low-shore pools showed different patterns with respect to tide period. High-shore pools showed significantly greater numbers of cystocarps at low tide than at high tide whereas cystocarp production did not differ between high and low tide periods in low shore pools. The possible mechanisms of gamete release are discussed in light of these results.

There is a great demand for algal cultures in studying morphology, cytology, ecology, cellular pathology and physiology, identification of species, and biotic interaction, and also in feeding small animals in culture for various studies. It is hoped that the following note may be of some use to those who want to start making pure cultures of marine phytoplankton organisms.

We present a 28S rDNA gene tree of selected Raspailiidae, Axinellidae and other demosponges to obtain insight into raspailiid phylogeny and character evolution. The Raspailiidae in our data set cluster in a well-supported clade, distinguished from Axinellidae, Agelasida and Hadromerida. Raspailia (s.s.), Eurypon, Sollasella, Aulospongus and Ectyoplasia form a Raspailiidae clade. Some Raspailia subgenera, in particular R. (Parasyringella), are not retrieved monophyletically. Trikentrion falls into the Thrinacophorinae, and not the Cyamoninae as earlier hypothesized. The axinellid genera Ptilocaulis and Reniochalina also cluster with Raspailiidae, distant from the other Axinellidae. The suitability of particular morphological characters for raspailiid phylogeny is discussed.

Five new species of Homoscleromorpha (Porifera) of four genera, Oscarella, Plakortis, Plakina and Corticium, are described from vertical walls of reef caves at depths ranging from 23 to 28 m in the Caribbean Sea. Oscarella nathaliae sp. nov. has a leaf-like thinly encrusting, flat body, loosely attached to the substrate and a perforated, not lobate surface. Oscarella nathaliae sp. nov. contains two bacterial morphotypes and is characterized by two mesohylar cell types with inclusions. Plakortis myrae sp. nov. has diods of two categories: abundant large ones (83–119 μm long) and rare small ones (67–71 μm long) with sinuous, S-bent centres; triods Y- or T-shaped (18–5  μm long), and abundant microrhabds (5–12 μm long). Plakortis edwardsi sp. nov. has diods of one category with thick, sinuous, S-bent centres (110 to 128 μm long); triods T-shaped (actines 28–59 μm long). It is the only species of this genus showing small diods (22–31 μm long). Plakortis dariae sp. nov. has diods of two categories: large ones (67–112 μm long) and small, rare, irregular ones, slightly curved, often deformed with one end blunt (30–59 μm long); triods rare and regular (actines 20–44 μm long). Corticium diamantense sp. nov. has oscula situated near its border, regular non-lophose calthrops of one size-class, very rare tetralophose calthrops and candelabra with the fourth actine ramified basally in 4–5 microspined rays. In addition, a re-description of Plakina jamaicensis is based on newly collected material and the type specimen. Plakortis jamaicensis has a convoluted brain-like surface; well developed sub-ectosomal cavities; irregular sinuous diods, triods, calthrops, rare monolophose calthrops, rare dilophose calthrops, rare trilophose calthrops and common tetralophose calthrops. Molecular ‘barcoding’ sequences for mitochondrial cob are given for Plakortis edwardsi sp. nov., P. dariae sp. nov., Plakina jamaicensis and Corticium diamantense sp. nov. An identification key for all western Atlantic Homoscleromorpha is provided.

The study aimed to unravel the interaction between ocean acidification and solar ultraviolet radiation (UVR) in Chaetoceros curvisetus. Chaetoceros curvisetus cells were acclimated to high CO2 (HC, 1000 ppmv) and low CO2 concentration (control, LC, 380 ppmv) for 14 days. Cell density, specific growth rate and chlorophyll were measured. The acclimated cells were then exposed to PAB (photosynthetically active radiation (PAR) + UV-A + UV-B), PA (PAR + UV-A) or P (PAR) for 60 min. Photochemical efficiency (ΦPSII), relative electron transport rate (rETR) and the recovery of ΦPSII were determined. HC induced higher cell density and specific growth rate compared with LC. However, no difference was found in chlorophyll between HC and LC. Moreover, ΦPSII and rETRs were higher under HC than LC in response to solar UVR. P exposure led to faster recovery of ΦPSII, both under HC and LC, than PA and PAB exposure. It appeared that harmful effects of UVR on C. curvisetus could be counteracted by ocean acidification simulated by high CO2 when the effect of climate change is not beyond the tolerance of cells.

Sea urchins can have important ecological effects on benthic communities through their aggregation and feeding behaviour. Urchin movement has been demonstrated to be negatively affected by wave action, but the impact of unidirectional tidal currents on urchin movement has not been investigated. This study examines the effect of unidirectional water velocity on the direction of displacement and movement rate of the green sea urchin, Strongylocentrotus droebachiensis. In laboratory flume experiments there was a clear effect of water currents on the displacement of sea urchins. At speeds ≤30 cm s−1 urchins moved across the current in a downstream direction, but at speeds of ≥36 cm s−1 the urchins switched directions by more than 90° and moved across the current in an upstream direction. There was a significant effect of flow speed on urchin movement speed, with urchin movement speed decreasing as water current speed increased.

Under the assumption that dislodged intertidal gastropods have developed some adaptations to return to their original habitat, we investigated the cues involved in the navigation ability of Littorina littorea, following a simulated wave-dislodgement. Return rates decreased by 2 and 4-fold in the absence of chemical cues at the surface of the sediment and the rock, respectively. The 19-fold decrease in return rates observed in the absence of both cues suggests their synergistic effect on L. littorea navigation. Chemoreception might be much more involved in the navigation and the survival of intertidal gastropods following wave dislodgement than previously thought.