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.

There is some controversy about the strength of the stock of mackerel in the Celtic Sea and off the coasts of Cornwall and Ireland, and it is difficult to find out if the numbers of mackerel in this area have fluctuated in the past (Johnson, 1977; Lockwood & Johnson, 1976; Lockwood, 1978; Coombs, Pipe & Mitchell, 1977,1979, 1980). The earliest complete survey of the south-west spawning grounds was made in 1937–9 (Steven & Corbin, 1939; Corbin, 1947) and was principally designed to show the seasonal and geographical pattern, not provide a basis for stock evaluation. Nevertheless, this survey is the only information we have about the breeding of mackerel in the days before the war when fishing was performed with drift-nets and lines, a period when we can assume exploitation was very much less intense than today when trawls and purse-seines are used. Attempts to use the 1937–9 data for estimation of the pre-war stock have been regarded as giving unsatisfactory results (Walsh, 1976). The data from the 1937–9 surveys were defective because we did not know the influence of the depth of fishing of the nets in relation to the vertical distribution of the eggs, nor the efficiency and catching capacity of the nets for sampling eggs and post-larvae.

Upper critical thermal limits were measured as heat coma temperatures in Littorina species (Mollusca: Gastropoda) from sites around the British Isles. Thermal tolerance was found to be stable within a population but extensive variation occurred between populations and species. The majority of species examined displayed heat coma values of around 30°C and did not show a positive correlation with shore height. The highest capacity for thermal tolerance was found along the coast of South Wales, while the lowest was found on the south-west coast of Ireland and on the east coast of Scotland.

In the examination of a total of about twenty-four thousand mussels from various localities in Devon and Cornwall—estuaries of the Fal, Hamoaze, Yealm, Teign and Camel, and the Promenade Pier, Plymouth— it has been observed that those from various parts of the Fal Estuary included a high percentage of specimens with the gills in an abnormal condition, whereas such abnormalities were rare or absent in other localities.

Descriptions of the hydroid Zanclea implexa (Alder) in British waters have been given by the following authors, Alder (1857, as Tubularia implexa and Coryne pelagica), Allman (1859, as Coryne Briareus), Strethill Wright (1859) and Alder (1862 as Coryne implexa), Allman (1864 as Zanclea implexa and 1872 as Gemmaria implexa) and Hincks (1872, as Zanclea (Gemmaria) implexa). All these descriptions have been based upon full grown colonies in which the hydranths had a perisarc on the hydrocaulus.

Laboratory-reared herring larvae adjusted several characteristics of their swimming behaviour to the presence of food in the experimental tank. When food density was low, as in the outer limits of a food patch in the sea, the larvae increased their turning frequency, an exploratory behaviour to locate the centre of the patch. At a higher prey concentration, such as in the centre of a food patch, the larvae crossed their previous swimming path more frequently, indicating a local search strategy aimed at foraging in the centre of the patch.

The prey of actively foraging planktonic predators, such as fish larvae, is patchily distributed. The main factors governing the ability of the predators to encounter prey are the relative velocities of predator and prey, and the prey detection radius by the predator relative to the distance between prey items (Gerritsen & Strickler, 1977). The enhancement of encounter rate by turbulence through its effect on relative velocity has been widely discussed in the literature since Rothschild & Osborn's (1988) publication. However, an effective forager should be able to adjust its behaviour to optimize prey encounter by, for example, altering its position in the water column in relation to conditions of turbulence, or modifying its searching behaviour in response to spatial aggregation of prey. This latter aspect has received comparatively little attention. Different swimming modes have been described in herring (Clupea harengus L.) larvae and in larvae of many other fish species. Foraging larvae swim in a more linear path between food patches and follow a more complex track when a patch of prey is located.

The effects of environmental temperature on haemocyte antibacterial activity were investigated for the shore crab, Carcinus maenas. Haemocyte lysate supernatants (HLS), prepared from groups of five animals (sampled at monthly intervals over one year and covering a range of temperatures) were assayed for their ability to reduce viable counts of the marine bacterium Psychrobacter immobilis NQMB 308 during 4 h incubation. Parallel measurements were made of HLS protein concentration, total haemocyte count and ambient aquarium sea-water temperature. Despite wide variation in the values derived for each parameter, the results show that powerful antibacterial activity was present in HLS for all months except February and August, when respective aquarium water temperatures were at their lowest and highest for the year. This emphasizes the importance of environmental factors in immune capability: a phenomenon of significance not only to commercial shellfish culture but also for the use of immune parameters as biomarkers of environmental disturbance.

This paper is the fourth in a series dealing with the fecundity of flatfish (Bagenal 1957 a,b, 1958), and is concerned with the egg numbers in ripening female plaicePleuronectes platessa L. caught in the English Channel.

On 27 November 1957, eighty-five plaice with maturing ovaries were caught in Rye Bay, Sussex; on I December, eight similar fish were caught in Lyme Bay, and duringDecember sixty-four locally caught female plaice were brought in to the Plymouth Laboratory. The dates of the collections were chosen because in January 1957 I had found that a small proportion of the Plymouth plaice were spent. All the fish caught in November and December were at a suitable stage for fecundity estimation: that is, the eggs were well developed though none had begun to turn translucent.

Eight populations of Caprella penantis, three of Caprella dilatata and two of Caprella andreae, collected from different sites all over the world, were selected for genetic study. Thirteen primers were tested, and the phenogram, based on the similarity coefficient of Nei & Li and the UPGMA method, separated clearly C. dilatata and C. andreae from the populations of C. penantis, supporting the validity of these three species, traditionally considered altogether under the old ‘acutifrons’ complex. Populations of C. penantis (including, at least, forms simulatrix, testudo and lusitanica) from Spain, Portugal, Morocco, Japan and Brazil were clustered together in the RAPD analysis, indicating that, probably, all the specimens of C. penantis could belong to the same species, in spite of morphological variations in the pleura, gills, robustness and presence/absence of proximal projection in adult male gnathopod 2 propodus. The only population which showed genetic differentiation within the C. penantis complex was the form gibbosa from Coquimbo, Chile. Future analysis based on different molecular approaches (mtDNA, 18S rRNA, ISSR) and additional material from other world areas, should be conducted to confirm these results.

The north-eastern Aegean Sea (NEA) is a marine system of high hydrological complexity, principally induced by the inflow and subsequent advection of the low salinity (<30) Black Sea water (BSW). This water mass occupies the upper layer (~0–20 m) of the NEA and plays a key role in the determination of circulation patterns and the generation of various frontal and eddy structures. Here we are concerned with the examination of mesozooplankton assemblages in the NEA during the thermal stratification period (July 2004) in two discrete sampling layers: (a) Layer 1 (from the base of halocline to the surface: ~0–20 m) which is directly influenced by BSW; and (b) the deeper ~20–50 m layer (Layer 2). Our main objective was to assess the response of mesozooplankton to the BSW and the associated hydrological structures. In July 2004, the BSW was mainly restricted in the eastern part of the NEA where it was entrapped in a ~50-km wide anticyclonic gyre (Samothraki gyre). A marked spatial differentiation in mesozooplankton assemblage structure, significantly related to this hydrodynamic partitioning, was detected in Layer 1. Sampling sites under the direct influence of low salinity–high temperature gyre waters were characterized by a considerably higher mesozooplankton stock than the remaining area, mainly due to the outstanding numerical dominance of the cladoceran species Penilia avirostris. Copepods displayed notably low densities within the gyre and low species diversity, the calanoid Temora stylifera was the only abundant species. The mesozooplankton community outside the gyre zone shifted towards lower levels of total abundance, with a lesser contribution of cladocerans and an increase in the importance of small-sized copepods (e.g. Acartia clausi, Paracalanus parvus, copepodites of Oithona spp. and Clausocalanus spp.). In the subsurface layer (Layer 2), the mesozooplankton community also exhibited spatial heterogeneity which could be hardly explained by variability in environmental parameters. The periphery of the anticyclone below the halocline was distinguished from the remaining neritic area, presenting markedly high mesozooplankton productivity and distinct group composition. An inverse pattern in the mesozooplankton stock vertical distribution was observed at the periphery of the gyre (Layer 2> Layer 1) comparative to the remaining sites (Layer 1 > Layer 2), which was mainly due to unusually high concentrations of surface-living zooplankters below the halocline. The latter could be explained in terms of expected water flow patterns in an anticyclonic eddy.

The use of freeze-branding as a field-marking technique for flatfish is described. Similar recapture rates were obtained for flounders marked on the coloured, or eyed, side and for those marked on the white, or blind, side during the first two years after marking. Brands on adult flounders were still identifiable more than four years after release of the fish. The branding technique is also applicable to plaice.

This paper evaluates if the bivalve Tawera gayi from southern South America represents an opportunity to test ecological variability and environmental changes during the last 6000 years in southern South America. For this purpose, we analyse both modern and fossil (mid-to-late Holocene) T. gayi shells from Tierra del Fuego using different techniques, including taphonomy, stable isotopes, cathodoluminiscence (CL) and linear morphometrics. Taphonomic analysis shows that differences between modern and fossil shells appear best related to local variations of physical factors such as current speed, wave action and freshwater input along the non-uniform Beagle Channel coast. However, slight changes of hydraulic energy regimes throughout the Holocene cannot be ruled out. The analysis of stable isotopes on T. gayi shells indicates a mixing of oceanic waters with freshwater from precipitation, river runoff and glacier meltwater during the mid-to-late Holocene. The high depletion of δ18O at ~4400 years before present would be associated with a period of warmer temperatures, the so-called Hypsithermal. Under CL modern and fossil T. gayi shells show a well defined pattern related to the growth dynamics of the shell, which can lead to a better understanding of its biology, adding details to further palaeoenvironmental analysis. Finally, conventional metrics shows that fossil T. gayi shells are smaller and shorter than modern shells. These differences could be related to Holocene environmental changes, but here are best explained on the basis of a predator–prey relationship. This study shows that T. gayi may be a good candidate for looking at evidences of environmental changes in southern South America, and multi-proxy data are necessary to better understand the driving mechanisms of ecological variability and changes over short geological time intervals of few thousands of years.

This study describes for the first time the reproductive traits of the warm-water pompano, Trachinotus ovatus. Specimens were sampled from landings by artisanal fishing vessels in the NW Mediterranean. Monthly collections, from July 2010 through to September 2012, yielded 226 individuals (118 females and 108 males). The size at 50% maturity (L50) was estimated at 30.9 and 29.1 cm TL for females and males, respectively. Specific reproductive traits, such as oocyte size-frequency distributions, presence of recent post-ovulatory follicles along with oocytes in the final phases of gonadal development, and massive atresia in post-spawning individuals, indicated that pompanos are multiple batch spawners with asynchronous oocyte development and indeterminate fecundity. Monthly variations in the gonadosomatic index and in the phases of gonadal development indicated July and August as the spawning season. There were also noticeable inter-annual variations in spawning phenology, mean diameters of the oocytes, relative batch fecundity and eggs quality, all of which corresponded to changes in sea surface temperatures. This study enhances our understanding of the need for research into the reproduction of warm-water species, which are currently expanding into the increasingly warmer waters of the world's more northerly seas and oceans.

The distribution pattern and nocturnal surface behaviour of the deep-sea medusa Periphylla periphylla in a Norwegian fjord was studied. Medusa abundance, size distribution and condition were determined, using surface collections, net tows and ROV-based video profiles. Only larger, mature medusae reached the surface and aggregated into small groups of both sexes, whereas juvenile medusae remained in deeper waters. Observations on the behaviour and cytology of aggregated medusae suggested a mating strategy. We hypothesize that this behaviour is the by-product of a holopelagic life history, developed in a more oceanic deep environment with low species abundance, as surface aggregation increases the chance of encounter and mating.

Samples historically collected and analysed by the Continuous Plankton Recorder (CPR) survey were used to describe the distribution of coccolithophores (class Prymnesiophyceae) in the north-east Atlantic and the North Sea. In the routine CPR analysis, members of this group are simply identified as ‘coccolithophores’ and not to any further taxonomic level. From this analysis, the 200-m depth contour marked a point of distinct transition between high coccolithophore occurrence (off the shelf) and low coccolithophore occurrence (on the shelf). Thirty-three CPR samples that had been collected between 1979–1992, were re-examined and the coccolithophores identified to a more detailed taxonomic level. Among the species identified was the bloom-forming coccolithophore, Emiliania huxleyi. Thus archived CPR samples could potentially be re-analysed to assess regional, seasonal and decadal changes in the occurrence of this species.

Long-term tagging studies, particularly those that target life stages away from nesting beaches can provide important insights in key life history traits, which are essential for the effective management of endangered species. The coast of Bahia hosts important green turtle foraging areas, but information on demography, spatial use and foraging ecology in this region is lacking. Here, we (1) examined the size-class structure of green turtles in Bahia, (2) compared the size distribution from Bahia to other foraging aggregations in Brazil, and (3) studied the somatic growth dynamics. Additionally, we investigated the (4) diet, (5) habitat use and (6) activity patterns of green turtles along shallow reefs in Bahia. From 2009 to 2013, 322 green turtles were captured and 44 were recaptured between 7 and 1218 days after initial tagging. Curved carapace length varied from 32.9 to 122.5 cm. Mean annual growth rate was 3.03 ± 1.18 cm year−1. The diet of the turtles was mainly composed of red algae of the family Gelidiaceae, Gelidiellaceae and Cystocloniaceae. There was a positive relationship between the abundance of red algae and the number of turtle sightings, with a significant increase in foraging activity during late afternoon. This study highlights the importance of this area as a mixed foraging aggregation of juvenile and adult green turtles, and reveals that foraging grounds for this species in Brazil exhibit southern immature-dominated assemblages and northern mixed aggregations. Areas with high aggregation of green turtles comprising individuals from different life stages must be targeted for conservation management.

Studies made on the cod of the Barents Sea showed that in the adult female fish there were regular seasonal variations in the level of calcium and vitamin A aldehydes in the blood (Plack & Woodhead, 1966: Woodhead, 1968). These changes were directly related to each other (Woodhead & Plack, 1968) and it was suggested that the changes of both blood constituents might be influenced by oestrogen secretions from the ripening ovary. It has now been confirmed that oestradiol treatment increases the level of vitamin A1 aldehyde in immature cod (Plack & Pritchard, 1968), and the present paper describes the effect of oestrogen treatment on the concentration of calcium in the plasma, also relating this to vitamin A aldehyde changes.

Patches of a very dense tube mat biotope were found during fish habitat studies in the eastern English Channel. At three locations in the lows between linear sand banks off the French coast an un-described small Chaetopterus sp. occurred with small Lanice conchilega as an enriched sediment stabilizing biotope. This biotope was distinct though having similarities to other tide swept sub-tidal biotopes dominated by L. conchilega. Using cameras and side-scan sonar it was seen to overlay heterogeneous cobbles and shell hash with intermittent rippled sand veneer. The patchiness of this enriching biogenic feature contributed to the variability in trawl catches of fish.

Most current literature concerning moult control in crustaceans concludes that initiation of premoult is controlled by changes in the level of moult-inhibiting hormone (MIH) produced by the eyestalk neurosecretory organs. MIH is thought to act by repressing the secretory activity of the Y-organs, preventing increases in circulating ecdysteriod levels, necessary for moulting (see Kleinholz & Keller, 1979). This hypothesis is based upon the observation that eyestalk removal, by removing the source of MIH, leads to accelerated moulting (see Passano, 1960; Vernet-Cornubert, 1961; Sochasky, 1973, for reviews), and it survives despite many contrary reports indicating that moulting is unaffected by eyestalk removal (Sochasky, 1973). Perhaps the best known of the most contradictory data of this nature have been reported for Palaemon serratus for which Drach (1944, 1947), Panouse (1946, 1947) have shown that eyestalk removal generally accelerates moulting in this species. In contrast, Scheer & Scheer (1954) and Carlisle (1953) demonstrated no moult inhibition in this species following eyestalk removal.

Age, growth and reproduction biology of the golden grey mullet, Chelon auratus (Risso, 1810) have been studied in the Istanbul Golden Horn area. Fish length ranged from 13.4–46.8 cm, and age from 1–10 years, respectively. The sex ratio (female:male) was 1:1.08. The length-weight relationship was estimated as W = 0.0127L2.89, W = 0.0099L2.97 and W = 0.0156L2.82 for both sexes combined, females and males, respectively. The von Bertalanffy growth equation parameters were: L∞ = 57.52 cm, K = 0.1 year−1, t0 = −2.24 year for pooled data. The gonadosomatic index (GSI) values indicated the major spawning period was between August and November, and the minor spawning peak between March and April. The highest GSI values were observed in September. The length and age of sexual maturity were estimated as 26.2 cm and 4 years for males and 24.1 cm and 3 years for females.