A 3-D hydrodynamic model of the circulation, salinity and temperature within the embayment of Plymouth Sound, UK and its surrounding English Channel waters has been implemented. Thorough validation of the model shows that the main hydrographic features of the region, as characterized by these variables, are reproduced. The general flow characteristics, and the resultant distribution of freshwater from the main riverine source (the River Tamar), are described. The potential fate of contaminant releases within Plymouth Sound is investigated. Whitsand Bay, located south-west of Plymouth Sound, is shown to be a likely recipient for a proportion of these contaminants, irrespective of where in the Sound the release occurs, and as such is considered to be vulnerable to pollution events originating there.

The composition and structure of a molluscan assemblage was studied in a deep subtidal eelgrass bed located in southern Spain before and after the eelgrass decline experienced during 2005 and 2006 due to illegal trawling by fishermen. Sampling was undertaken in summer 2004 (with eelgrass) and summer 2007 (without eelgrass) in an extensive eelgrass bed located in Cañuelo Bay (12–14 m depth) and in the same area once the eelgrass bed disappeared. Eelgrass was completely absent in those samples of summer 2007 and an increase of the organic content and mud was registered in the sediment between 2004 and 2007. The density and the richness of molluscan species decreased significantly in summer 2007, especially for epifaunal gastropods associated with the leaf and sediment stratum. Some species disappeared completely in summer 2007 such as the dominant periphyton grazers Jujubinus striatus and Rissoa spp., the egg feeder Mitrella minor and the seagrass feeder Smaragdia viridis as well as the infaunal bivalve Solemya togata. Other species increased their densities such as the carnivores Cylichna crossei or C. cylindracea as well as the bivalve Nucula nitidosa. Some dominant infaunal species, such as Chamelea gallina, Spisula subtruncata or Tellina fabula did not significantly change their densities. The composition and structure of the assemblages in summer 2004 and summer 2007 was significantly different according to the Bray–Curtis similarity index using qualitative and quantitative data and considering the entire assemblage (epifaunal and infaunal species) or only the infaunal species. The registered changes in the molluscan assemblage may have produced cascade effects in higher trophic levels because molluscs generally represent an important food source for some decapods and fish. Urgent conservation measures are needed for protecting the remaining fragmented eelgrass beds of southern Spain from further illegal fisheries activities and other types of human impacts (e.g. sand extraction and coastal infrastructures), because they support the most diverse faunistic communities for eelgrass beds in Europe due to their bathymetry and geographical location.

1. Gonad examinations were made on monthly samples of Echinus esculentus from Plymouth in 1934, 1935, and 1936.

2. Spawning is from February–March to May, 50% spawning occurring at a temperature of 9.2–9–7° C. compared with 7.0—7.8° C. in the Isle of Man. There was a winter drop in gonad volume one year, but not the other.

3. The nature, distribution and source of the pigments in the shell are discussed, and it is shown that pigment is found in quantity in the intestine only in the summer and autumn.

4. The known facts with regard to the seasons of growth, spawning, etc., are brought together into a generalized diagram.

This note concerns a series of experiments to determine the best conditions of salinity, temperature and pH for cultivating the euryhaline phagotrophic dinoflagellate Oxyrrhis marina Dujardin.

The strain of Oxyrrhis employed was isolated from a brackish pool at Tvarminne, Finland (Droop, 1953a, b). The culture medium for the experiments contained soil extract and an artificial sea water, SW 1 (NaCl, MgCl26H2O, KCl, and CaSO42H2O in the proportions by weight 15:2.5:0.4:0.5), and for food a small quantity of the yeast Saccharomyces exiguus was administered daily from an agar culture with a wire loop.

Daily increments were demonstrated in the sagittae of the lesser sandeel, Ammodytes marinus, maintained in outdoor enclosures. Daily increment formation was also inferred for wild sandeels from an analysis of changes in age composition within a series of field samples. A comparison between sagitta microstructure and morphological development of larval and juvenile sandeels indicated that the first sagitta increment was formed around the time of hatching. Yolk-sac absorption and larval metamorphosis were accompanied by changes in otolith microstructure.

The lesser sandeel, Ammodytes marinus (Raitt), is important as a prey item for many species of fish, seabirds and marine mammals (Furness, 1990) and supports major fisheries in the North Sea (Anon., 1991). However, little is known about the ecological processes affecting year-class strength in this species. Otolith microstructure has been demonstrated to be a potentially useful tool for investigating early survivorship in fishes, since otoliths may provide a chronological record of early growth and life-history events (see Campana & Neilson, 1985). This paper examines the usefulness of otolith microstructure for studies of sandeel growth, from investigations of increment periodicity and a comparison between otolith microstructure and morphological development.

Lessepsian migrant Siganus rivulatus is reported for the first time from the Adriatic Sea, substantially further north than its usual area of occurrence in the Mediterranean Sea. Two specimens (111 mm total length [TL] and 149 mm TL) were captured by beach seine on 5 October 2002 off islet Bobara, near Cavtat (southern Adriatic). Morphometric and meristic characteristics of the specimens are provided. The possible explanations of this occurrence are discussed.

This study was conducted between January and December 1995 at Armação do Itapocoroy, Penha, Santa Catarina, southern Brazil. Monthly samples were carried out in the morning, afternoon, and evening using two over-trawls with 6 m at the opening, 3·0-cm mesh at the outer part and 2·0-cm mesh in the bag. Dardanus insignis was collected year round but with higher densities in September and October. The hermit crabs were more abundant during the evening than the afternoon but no differences were recorded between morning and both evening and afternoon. Females were slightly more abundant than males but the sex ratio did not differ from 1:1. Females were more abundant in the smallest size-classes (<1·8 cm) while males outnumbered females in the largest ones (>2·2 cm). The individuals of this population of D. insignis have a mean cephalothoracic length of 1·89±0·40 cm (range 1·00 to 3·90 cm) and a mean weight of 40·26±27·06 g. The size distribution showed an unimodal pattern, with males being larger than ovigerous females, which, in turn, were larger than non-ovigerous females. Dardanus insignis showed a seasonal reproductive pattern with a peak from September to November and complete absence of ovigerous females from April to August. The von Bertalanffy growth function (VBGF) with temporal oscillation fitted for this population of D. insignis had the following parameters: L∞=4·40 cm, K=0·60, C=0·95, WP=0·35. Recruitment was estimated to start in September and was extended to the following months. Estimates of longevity ranged from 20 to 62 months. A mortality rate of 2·21 was estimated based on the length converted catch curve. The cephalothoracic length of males and females showed, respectively, positive and negative allometry with both cephalothoracic width and crab weight.

Adult individuals of Talitrus saltator were tested for celestial orientation in a plexiglass bowl covered with colour filters of different wavelengths. Results show that T. saltator can recognize the sun and use it for orientation only at γ <450 nm. At γ >500 nm, the sight of the sun (and sky) only induces phototactic behaviour. It has also been confirmed that an important celestial orienting factor is perceived in the UV range. Variations in populations from diversely oriented coastlines are discussed. Preliminary results of electroretino-graphic responses indicate the presence of at least two visual pigments in the eye and a steep decrease in sensitivity for γ >500 nm.

We estimated the abundance of Antillean manatees (Trichechus manatus manatus) through a large-scale project conducted in 2010 in north-eastern Brazil and evaluated the efficacy of an aerial survey for conservation purposes. Two observers conducted the survey via flights that maintained an altitude of 150 m and an air speed of 140 km h−1, covering over 2590.2 km2 of the coastline. Strip transects were flown in a zigzag pattern. A total of 67 manatees (on- and off-effort) were recorded in 55 sightings. Historical published records of occurrence were formally incorporated using a Bayesian approach. We estimated the manatee population for north-eastern Brazil in the form of a posterior distribution with a mean of 1104 individuals and a 95% posterior probability interval ranging from 485 to 2221 individuals, which indicates high uncertainty. More large-scale studies in the region are warranted to understand temporal trends, in addition to further studies in hotspot areas, with smaller spatial scales, to reduce the coefficient of variation and to allow the use of improved techniques for monitoring the manatees. A greater emphasis on species-specific characteristics and methods to enhance detection probability (e.g. dual observers) are also recommended. The conditions prevailing along the study area were not conducive to aerial surveillance; thus, the results are not a precise estimate of the manatee population. However, these highlight the importance of conservation efforts for the Antillean manatee, considered the most endangered aquatic mammal in Brazil.

Idotea pelagica Leach is typically found on exposed shores among barnacles and stunted fucoid algae. It has been recorded from Norway to the coast of France, excluding the low salinity waters of the inner Baltic (Naylor, 1972). Studies have been made of its feeding (Naylor, 1955a), external morphology (Naylor, 1955 b) and ecological distribution (Naylor, 1955 c).

The colossal squid (Mesonychoteuthis hamiltoni) is the world's largest invertebrate and its large size and some unique morphological characters have fuelled speculation that it is an aggressive top predator in the circum-Antarctic Southern Ocean. Here, we present estimates on the metabolic and energetic demands of this cold-water deep-sea giant. The estimated mass-specific routine metabolic rate for the colossal squid at 1.5°C was 0.036 µmol O2 h−1 g−1 and the projected daily energy consumption (45.1 kcal day−1) was almost constant as a function of depth in the nearly isothermal Antarctic waters. Our findings also indicate the squid shows a slow pace of life linked with very low prey requirements (only 0.03 kg of prey per day). We argue that the colossal squid is not a voracious predator capable of high-speed predator–prey interactions. It is, rather, an ambush or sit-and-float predator that uses the hooks on its arms and tentacles to ensnare prey that unwittingly approach.

This study compared the scaling of the glycolytic enzyme lactate dehydrogenase (LDH) and the Krebs cycle enzyme citrate synthase (CS) in the swimming muscle and tentacle tissue of the mesopelagic coronate scyphomedusa Periphylla periphylla in two populations living under different oxygen minimum layer conditions. The LDH and CS activities in these tissues of two other coronate scyphomedusae (Paraphyllina ransoni and Periphyllopsis galatheae) and the bathypelagic narcomedusa Aegina citrea were also studied. The scaling of these two enzymes along with total protein was investigated in whole organism homogenates of the surface-living scyphomedusa Aurelia labiata. Mass-specific LDH activities in swimming muscle showed positive scaling in relation to body size in Periphylla periphylla collected off California and Hawaii. Mass-specific LDH activities in tentacle tissue increased with regards to increasing mass only in specimens of P. periphylla collected off California. The LDH values of the scaling coefficient, b, in swimming muscle and tentacle were significantly higher in P. periphylla collected in the low oxygen waters off California than from those collected off the Hawaiian Islands in a higher oxygen environment. The LDH showed a significant decrease with body size in Aegina citrea swimming muscle and in Aurelia labiata whole animal homogenates. The largest species in this study, Periphyllopsis galatheae, had LDH activities similar to the smallest specimens of Periphylla periphylla. The results of this study suggest that the scaling of glycolytic activity is related to oxygen availability for P. periphylla. In Aurelia labiata, which is only exposed to episodic hypoxia, and Aegina citrea, scaling of glycolytic activity is not affected by oxygen availability.

In Torbay, Nemertesia antennina (L.) hosts more than 150 epizoic species, most of which do not occur on other substrata in the area (Hughes, 1975). Five species, the amphipods Ericthonius brasiliensis (Dana), Pseudoprotella phasma (Montagu) and Corophium sextoni Crawford, and the gastropods Cingula semistriata (Montagu) and Cingula semicostata (Montagu), constitute 68 % of the free-living epizoites and are sufficiently abundant throughout the year to allow a study of their life-histories.

This study presents electron microscopy (SEM, TEM) observations on the putative settlement receptors of the fourth antennulary segments. The TEM data from all nine setae are from the outer dendritic segment. Eight of them have morphological characteristics, indicating bimodal sensory properties while one seta (sE) is presumed to be a unimodal mechanoreceptor. We suggest that setae A and B are stimulated by the water flow, seta D is olfactory, seta E detects the topography of the substratum by touch, and the subterminal setae are touch chemoreceptors. No function is suggested for seta C.

This study presents new information on feeding habits of Guiana dolphins, Sotalia guianensis, in south-eastern Brazil, together with new regression equations to evaluate the weight and length of fish from otoliths, showing an overview on the knowledge about this species’ diet in this area. Eighteen stomach contents had been analysed and compared to 180 samples collected in another eight feeding studies. The analysed specimens were either incidentally caught in gillnets used in coastal waters by the fleet based in the Cananéia main harbour (25°00′S 47°55′W), south of São Paulo State, or found dead in inner waters of the Cananéia estuary between 2003 and 2009. Based on the index of relative importance analysis, the most important fish species were the banded croaker, Paralonchurus brasiliensis. Doryteuthis plei was the most representative cephalopod species. Stellifer rastrifer was the most important fish species observed in dolphins in inner estuarine waters and P. brasiliensis in recovered dolphins from coastal waters. Loliguncula brevis is the only cephalopod species reported from dolphins found in inner estuarine waters up to date. Doryteuthis plei was the most important cephalopod species observed in coastal dolphins. When considering other feeding studies, the most representative fish family in the diet of S. guianensis was Sciaenidae, which is mainly represented by demersal fishes. The main preys of S. guianensis are abundant in the studied areas, which may indicate an opportunistic feeding habit. The majority of them are not the most important target species by the commercial fishery in south-eastern Brazil.

A quantitative seasonal survey of the phytoplankton and small zooplankton has been made from the end of January to the end of August 1939, at a station, L4, with supplementary observations at a station off Rame Head, both near Plymouth. The results are compared with those of a fuller survey made in 1934.

The spring maximum in numbers of plant cells was late, not being reached until the middle of April.

The monthly means of the total numbers of animals caught were of the same order in the two years, but the numbers of copepods plus copepodites in 1939 were only two-thirds of those in 1934.

A method is described for measuring, for various angles of incidence, the polarization produced by reflexions from natural surfaces.

This method was tested by measurements on matallic surfaces of known properties and then used to study reflexions from the silvery gill cover of the bleak Alburnus alburnus (L.).

Althouth the reflecting surfaces of the gill cover are crystals of a dielectric guanine, there is no polarizing angle, and the reflecting properties of the gill cover resemble those of a sputtered aluminium mirror

The biological significance of these results is briefly discussed.

Variability in recovery of the introduced green alga Caulerpa racemosa has been investigated on a subtidal rocky shore in the north-western Mediterranean Sea. Two removal experiments were performed. The first was designed to test the effects of season on the early patterns of recovery of C. racemosa on a rocky bottom and on algal turf. In the second experiment recovery of C. racemosa on the rocky bottom and on algal turf was estimated from July–October 2000, the end of the vegetative period of the alga. Recovery of experimental plots occurred from adjacent populations of C. racemosa by stolon growth. In the first experiment, recovery occurred from August to November in all the experimental units, while no growth was observed during winter and spring. Recovery was significantly higher on algal turf than on rock during all vegetative periods. In both the habitats, recovery was quicker in summer than in autumn, even if differences between dates within each season were also significant. In the second experiment, three months after removal, the mean per cent cover of C. racemosa in algal turf was twice that on rock.

Recent experimental measurements have confirmed the accuracy of earlier calculations of the extent of hydrolysis of ammonium ions in sea water over a range of temperature and salinity. Tables of the percentage of un-ionized ammonia in sea water compiled from the calculated data can therefore be used with confidence in assessing ammonia toxicity in mariculture systems.

Measurements of fecundity are given for plaice (Pleuronedes platessa L.) sampled from Cardigan Bay. Values were compared with those obtained in 1953 from Cardigan Bay and from the eastern Irish Sea, and no differences were found; a marked contrast to results from the North Sea. Analysis of egg size showed that eggs develop earlier in older fish. A mechanism for ‘fine-tuning’ of fecundity is discussed. Size and age at maturity are calculated for Cardigan Bay plaice, and are compared with rates from surrounding areas. Plaice mature at an earlier age in Cardigan Bay.