Trachysalambria curvirostris occurs widely along the south and west coasts of Korea with a range extending from Kanghwado in the north-west, down to Sarangdo in the south-east. With seasonal warming of the waters starting in April, the shrimps begin to migrate from deep waters to the coastal area. Zoea and mysis larvae occurred from June to August. Sex ratio showed seasonal variations, with a mean value of 56·7% for the females. The species produces one cohort a year, with the ovaries ripening from June to July. Insemination appeared to take place from June to August, as more than half of the females sampled in the study over 15–16 mm carapace length were inseminated. Mean gonadosomatic index (GSI) reached a maximum between June and July. The smallest mature female found was 15 mm carapace length (CL). Size at 50% sexual maturity (CL50), determined from both mature females and inseminated females, was 15·37 mm and 16·49 mm CL, respectively. Fecundity was directly proportional to the size of the female, with clutch sizes varying from 16,380 eggs in the smallest female to 114,621 eggs in the largest, and the eggs ranged from 230 μm to 340 μm in diameter. The life span of females appeared to be 14–15 months according to size frequency distributions, while that of the male was 13–14 months. Population growth was estimated by the modified von Bertalanffy growth function incorporating seasonal variation in growth. Based on the growth parameters (K=2·00 y−1 and L∞=24·64 mm CL for females, and K=2·00 y−1 and L∞=19·00 mm CL for males) growth curves showed that females grew faster and reached a larger size at age than males. This result is supported by differences in growth performance indices (ϕ′).

INTRODUCTION

The small squid Alloteuthis, and the larger Loligo have elongate mantles chiefly made up of two distinct types of circular muscle fibres, partitioned by thin sheets of radial muscle fibres (Bone, Pulsford & Chubb, 1981).

Nerve terminals on both types of circular fibre and upon radial fibres contain 50 nm electron-lucent vesicles; preliminary pharmacological investigations (Bone & Howarth, 1980) indicate that L-glutamate is the excitatory transmitter at the terminals upon the circular fibres. In other cephalopods, such as Sepia, and the squids Lepidoteuthis and Taningia (Clarke & Maul, 1962; Clarke, 1967) there are in addition to the circular and radial fibres, layers of longitudinal muscle fibres in the mantle. Such longitudinal fibre layers are lacking over the greater part of the mantle in Alloteuthis and Loligo. In this note, we show that they are present only around the anterior margin of the mantle in these two squid, and that both these anterior longitudinal fibres and the radial fibres of the mantle are insensitive to L-glutamate, but contract in response to acetylcholine, as do the retractor muscles of the head and arms, and the siphon muscles.

The habitat preferences and niches of eight cetacean species inhabiting eastern tropical Atlantic waters between Angola and Gabon (1°N–11°S latitude) were examined. A total of 2873 cetacean sightings, recorded between January 2004 and June 2009, was assigned to 10 × 10 km grid cells and linked to four ecogeographical variables (EGVs): water depth, seabed slope, sea surface temperature (SST) and relative frontal strength. Classification trees revealed that the habitat preferences (in terms of the habitats sampled) of most species were primarily determined by SST (for Bryde's whale, sperm whale, short-finned pilot whale and common dolphin) and water depth (for Risso's dolphin, bottlenose dolphin and Atlantic spotted dolphin). Seabed slope was the most important EGV describing the presence of the striped dolphin. A principal component analysis was used to compare the niches of the species with respect to the four EGVs. Nineteen species pairs (68%) differed significantly in median principal component (PC) score for the first PC axis, suggesting differences in their niche centres for that axis. Sixteen species pairs (57%) differed significantly in PC score variance suggesting differences in the niche widths along the first PC axis. Water depth and SST were the most important variables for the first PC axis. Together, these results suggest that cetacean species inhabiting the eastern tropical Atlantic exhibit interspecific variation in their habitat preferences, and so differ in the niches that they occupy. These differences are most likely related to variation in prey species and foraging strategy.

Very few field studies of the population dynamics of starfish have been undertaken; such work depends upon being able to age individuals and identify age classes in the field. Information regarding growth rates in asteroids is notoriously difficult to obtain, due primarily to the absence of any method of assessing age, except where clear and obvious recruitment and regular growth provide size/age relationships. Numerous investigations of skeletal structures in asteroids by Smith (1940), Feder (1956), Hatanaka & Kosaka (1959) and Crump (1971) have failed to reveal any trace of growth lines similar to those found by Moore (1935), Jensen (1969) and Ebert (1970) in echinoids. In forcipulate asteroids, it is well established that growth depends primarily on temperature (Vevers, 1949; Hancock, 1958) and the availability of suitable food supplies (Mead, 1900; Galtsoff & Loosanoff, 1939; Smith, 1940; Vevers, 1949; Feder, 1956, 1970; Hancock, 1958). The food availability factor acts in such a way that it is impossible to tell the age of an adult starfish from its size; for example, in the spinulosan asteroid Patiriella regularts (Verrill), Crump (1969) found that specimens kept without food for 44 weeks lost 33 % of the original body weight, whilst P. regularts which had been fed on freshly killed crabs, showed a mean net increase of 629% of the original net weight over the same period.

The aim of this study was to compare the population structure of the invasive bivalve Isognomon bicolor in three different areas on the coast of Rio de Janeiro State and to verify its temporal variation. All the areas presented high densities, reaching more than 1000 live individuals per 100 cm2. The number of dead individuals and recruits was higher in Ilha do Brandão (Angra dos Reis) than in the other areas. The individuals sampled at Praia Vermelha (Rio de Janeiro) presented the highest maximum and mean sizes, compared to those found at Ilha do Brandão. In this area, vermetid molluscs are dominant and build a complex reef structure where only a few individuals of I. bicolor can really grow.

The gametogenic cycle of the banded murex, Hexaplex (Trunculariopsis) trunculus, from the Ria Formosa lagoon (Algarve coast, southern Portugal) was studied through macro- and microscopic analyses of the gonads during a 1-year study period (March 2003–February 2004). The overall samples presented a balanced sex ratio, with males dominating among smaller individuals and females predominating in larger size-classes. The gametogenic cycle of T. trunculus in the Ria Formosa lagoon comprised an extensive period of gonadal activity, with the simultaneous occurrence of distinct developmental stages of gametogenesis in both sexes almost year-round, and with males invariably presenting gonads in more developed stages of gametogenesis than females. Spawning occurred mainly from May to June 2003, apparently triggered by the rising seawater temperature during spring. Due to the extensive period of gonadal activity, T. trunculus exhibited a short resting phase that occurred simultaneously in both sexes between June and August 2003 and coincided with the period of warmest seawater temperatures. Considering these findings, a closed season in the fishing activity should be implemented during the main spawning period of T. trunculus (May and June), in order to protect the female broodstock and collective spawns.

Age and growth of the common guitarfish (Rhinobatos rhinobatos) were estimated from the north-eastern Mediterranean coast of Turkey. A total of 115 common guitarfish (66 females and 49 males) were sampled. Age determinations were carried out using vertebral sections. Alcian blue dying techniques were used to enhance the visibility of the band on vertebrae. The techniques have been used for the first time on elasmobranchs vertebrae successfully in this study. A total of 97 vertebrae of 115 were visible on the vertebral band in this study. Male and female common guitarfish ranged in age from 1 to 15 and 1 to 24 y respectively. Total length ranged from 42 to 147 cm for females and 39 to 124 cm for males.

The relationships between total length (TL) and total weight (TW) were presented as TW = 0.0014*TL3.1672 (R2 = 0.98) for females, TW = 0.0012*TL3.1947 (R2 = 0.98) for males and TW = 0.0012*TL3.1915 (R2 = 0.98) for both sexes. The parameters for von Bertalanffy growth curves were estimated as Linf  = 137.70±9.38 cm, K = 0.159±0.047, to = −2.180 ± 0.90 for pooled data.

Mirocaris keldyshi gen. nov., sp. nov. is described from the Mid-Atlantic Ridge, TAG Location (26°09′N 44°50′W). The family Mirocarididae is proposed to include the new genus. The taxonomic position and distinguishing characters (presence of hook-bearing thoracic epipods and rudimentary appendix interna on pleopods 2–4) of the new family as compared to the other families of the superfamily Bresilioidea (Bresiliidae, Disciadidae, and Alvinocarididae) are discussed, and revised diagnoses for these families are provided.

This paper describes phytoplankton abundance data collected in the Sea of Marmara in 2000 and identifies new species to the region. The quantitative sampling was carried out monthly at 3 stations and seasonally at 6 stations at depths of 0.5, 5, 10 and 20 m. Additionally, vertical samplings by plankton net from 15–0 m were carried out in order to determine the species diversity. Simultaneously measured physical (salinity, temperature and Secchi disc) and chemical parameters (dissolved oxygen, nitrate + nitrite, chlorophyll-a, phosphate and silicate) were evaluated together with phytoplankton data. One hundred and fifteen species were recorded which are members of 55 dinoflagellates, 42 diatoms, 11 silicoflagellates and 7 other groups. Those species include toxic species with high reproduction rates and species that are accepted as carrying risk. Blooms of Anabaena sp., Nitzschia longissima (Brébisson in Kützing) Ralfs in Pritchard and Prorocentrum triestinum Schiller species were observed during the study. Dictyocha antarctica Lohmann 1919, Dictyocha crux Ehrenberg 1840 and Nitzschia rectilonga Takano 1983 species were recorded for the first time from the coastal waters of Turkey. The maximum phytoplankton abundance has been observed during the winter and autumn seasons in the 0.5 and 5 m depths; the concentration of the diatoms was higher during late winter and autumn, however, the concentration of the dinoflagellates was always high during the whole year and they did not show a seasonal variation. The phytoplankton density was lower at the 20 m depths because of the low light penetration property of the Sea of Marmara.

Two new marine species of Gastrotricha: Chaetonotidae are described from West Greenland and Denmark. Some peculiar features suggest the affiliation of the two species to a new genus, for which the name Diuronotus is proposed. The affinity of these gastrotrichs with species of Musellifer, the only genus entirely marine and hermaphroditic, and possibly the most basal one along the Chaetonotidae evolutionary line, is discussed from a morphological point of view. The span of the geographical distribution of Diuronotus is discussed in the light of a record of an additional co-generic, undescribed species from the USA. The relationships of this genus will be important in reconstructing the evolutionary pathways within Gastrotricha: Chaetonotida.

growth and mortality rates of larval japanese spanish mackerel (scomberomorus niphonius) were estimated by using otolith daily increments in 1997 and 1998 in the sea of hiuchi, central seto inland sea. there was no day–night difference in the abundance and size-distribution of s. niphonius larvae in the 3–10 mm size-classes, indicating the larvae were efficiently collected by the larva-net used for sampling (1.3 m mouth diameter, 0.5 mm mesh). mean absolute growth rate (0.748 mm d−1 in 1997, 0.821 mm d−1 in 1998), weight specific growth coefficient (g: 0.402 in 1997, 0.444 in 1998) and mortality coefficient (m: 0.784 in 1997 and 0.625 in 1998) were among the highest reported for marine fish larvae. scomberomorus niphonius seems to have evolved survival strategies characterized by fast growth with strong piscivory that can reduce duration of the larval period with the high mortality. in 1997, spatial distribution of the larvae was not well corresponded to that of their prey, clupeid larvae, and the larval feeding incidence was lower than in 1998. recruitment potential assessed by examining the ratio of g:m was lower in 1997 (0.513 in 1997, 0.711 in 1998) due to the lower g and higher m values. prey fish availability may be one of the important determinants for the recruitment potential by controlling the larval mortality due to starvation and/or starvation-related predation.

Food and feeding activity of juvenile pompano Trachinotus ovatus (25–97 mm) collected in the summer–autumn in 2003 in coastal shallow-water bays in the south-eastern Adriatic were examined. Juvenile pompano were exclusively daytime feeders and fed in the entire water column, from surface to bottom taking not only plankton, but benthic and terrestrial species as well. Of 18 prey taxa identified, crustaceans—particularly copepods—were the major group, followed by benthic foraminiferans and insects. Feeding on benthic species is reported for the first time in this study.

Octomagelona bizkaiensis (Annelida: Polychaeta), a new genus and species of the family Magelonidae is described from the north-eastern Atlantic. The specimens were collected from the Capbreton Canyon, Bay of Biscay, at a depth of 1000–1040 m. The new genus and species differs from all known genera and species of the family Magelonidae by the presence of eight instead of nine thoracic chaetigers.

Details are given of the culture apparatus and methods found successful for the laboratory culture of species of Ectocarpus. In attempts to obtain uni-algal cultures of this genus several common methods were tried but only one of them, a modification of the plating technique, proved successful. Methods of washing and dilution were unsuccessful in giving bacteria-free cultures, presumably due to bacteria closely adhering to the cell walls. Ultraviolet irradiation was also unsuccessful but treatment with penicillin gave bacteria-free cultures of E. confervoides and E. secundus (Giffordia secunda).

Plasmodia of Labyrinthula almost invariably appear in the diatom cultures and other small marine aquaria which I have kept during the last several years for a variety of purposes in Glasgow. These aquaria are stocked with material from Millport, I. of Cumbrae, and I think it quite certain that the Labyrinthula is imported thence.

This amazing creature has attracted interest ever since it was first described by Cienkowski in 1867, and good figures of it have been published by Cienkowski (1867), Duboscq (1921), and Valkanov (1929). The following note is to be regarded as a commentary on previous work and a record of my own observations rather than as an exhaustive account of the organism.

The muzzled blenny Omobanchus punctatus is recorded for the first time in the Mediterranean Sea, collected among fouling organisms covering the frame of aquaculture cages at the entrance to the port of Ashdod, Israel. Its presence there is most likely due to accidental introduction attributed to ship-mediated transfer.

The residency behaviour of six specimens of spangled emperor, Lethrinus nebulosus, was studied by acoustic telemetry in the mooring area (3–6 m depth) of a marine protected area (MPA) in New Caledonia. The 3 smaller fish (34–49 cm FL) remained within the study site less than 6 hours. The 3 larger individuals (51–54 cm FL) were regularly detected within the study site during the survey (6.5 months). These fish followed similar diurnal patterns of detection. They use the study site as a resting area during the day and migrate each night to feeding grounds after sunset. However, their presence was higher when wind speed was low (<10 knots) during weekends and school holidays. These links reflect a possible impact of human feeding activity. Consequently, management policies should include measures to control feeding activities within MPAs to maintain marine communities in a state unaltered by human activities.

A literature review and new data are used to clarify geographical patterns of community response to release from heavy grazing by green sea urchins, Strongylocentrotus droebachiensis (O.F. Müller) within the north-west Atlantic region. Large geographical areas identified where urchin-removal experiments have not been conducted are the Passamaquoddy Bay area of the northern Bay of Fundy, the south and west coasts of Newfoundland, and southern Labrador. Within the north-west Atlantic region, there has been variation in the degree of domination by Laminaria species of post-urchin-removal communities. This is probably due, at least in part, to variation in the availability of Laminaria populations in refugia from urchin grazing. The following hypothesis is developed and given a preliminary test: in eastern Newfoundland, the absence of refugial Laminaria longicruris populations is due to periodic ice-scour. Despite the absence of significant Laminaria populations following short-term (<5 years) urchin-removal experiments in some areas, it is suggested that Laminaria spp. may be the natural, long-term community dominants in the absence of significant urchin grazing throughout the region. In view of the logistic problems involved in conducting long-term (6–15 years) urchin-removal experiments, it is suggested that urchin-removal/Laminaria-seeding experiments should be conducted within this region.

Spatial distribution of the southernmost population of the purple clam, Amiantis purpurata (Bivalvia: Veneridae), was described from systematic survey data (density and local biomass), and was related to environmental variables (depth and sediment). Geostatistical techniques were used to model and map density, and to estimate absolute biomass.

Spatial distribution was highly contagious: half of the population lives at densities up to 240 clams m−2. Higher clam abundance occur only at sites with finer and well sorted sediment and intermediate depth. Even when the demographic structure of the population was composed of three year-classes recruited between 1978 and 1980, local biomass and density exhibited a non-linear relationship between them, and discrepancies between their distributions of frequency, their relationship with depth, and variographic analysis.

The spherical model was fitted to the experimental variograms. Anisotropy was explored and introduced into the model. The resulting map shows the location and extension of the patches in the study area; they conform a fringe where the highest concentrations are oriented parallel to the coast line, interrupted by small shoals. No anisotropism was evident in the variographic analysis of local biomass. The kriged mean was 3369 g m−2; and estimated total biomass was 53,290 tn.

Such differences between density and local biomass seem to be linked to compensatory processes involving biomass, growth and mortality, originated at the scale of individual overlapping neighbourhoods.

Relatively little is known about the distribution and diversity of marine mammals around offshore anthropogenic structures. We present results obtained from incidental sightings of marine mammals around oil and gas installations located 200 km off the Danish coast. A total of 131 sightings corresponding to about 288 animals were reported between May 2013 and May 2016. A total of seven marine mammal species were identified, five cetaceans: harbour porpoise (Phocoena phocoena), minke whale (Balaenoptera acutorostrata), white-beaked dolphin (Lagenorhynchus albirostris), killer whale (Orcinus orca), pilot whales (Globicephala spp.) and two species of pinnipeds: harbour (Phoca vitulina) and grey seals (Halichoerus grypus). The most sighted species were harbour porpoise (41%) and minke whale (31%). Relative counts and biodiversity of marine mammals observed around installations corresponded well with the expected distribution in the central North Sea. Several taxon-specific correlations were identified between number of sightings and environmental parameters (depth and latitude) or installation characteristics (installation aerial footprint). Furthermore, 85% of sightings were made during spring and summer and it is unclear whether the pattern observed reflected a natural seasonal occurrence of marine mammals in the area or an effect of reduced effort during autumn and winter. Despite the potential caveats, results obtained during this programme provide an insight into the relationship between marine mammals and oil and gas offshore installations in the North Sea.