The bed-forming brittlestars Ophiothrix fragilis, Ophiocomina nigra and Amphiura chiajei from Oban Bay, Scotland were studied using methods previously employed to study chemoautotrophic symbioses. Ophiothrix fragilis and A. chiajei both contain symbiotic bacteria (SCB) while Ophiocomina nigra is non-symbiotic. Samples were taken of Ophiothrix fragilis at approximately two-week intervals for one year. Symbiotic bacteria numbers were determined by direct counting of homogenates of the arms of 50 individual brittlestars. Water samples were analysed for chlorophyll content. Stable isotope ratios for carbon and nitrogen were determined for each homogenate sample. Regular SCB counts were made on the infaunal brittlestar A. chiajei. Homogenate samples of Ophiothrix fragilis, A. chiajei and the non-symbiotic Ophiocomina nigra were analysed to produce fatty acid profiles for each species. Symbiotic bacteria count varied by up to one order of magnitude in both Ophiothrix fragilis and A. chiajei with no evidence of seasonality in this variation. Symbiotic bacteria number was inversely correlated with δ15N but no relationship was established with δ13C. 16:1ω7 and 18:1.ω7 fatty acids were used as putative bacterial markers. Both symbiotic species had higher percentages of 16:1ω7 than the non-symbiotic Ophiocomina nigra. However, only Ophiothrix fragilis appeared to receive appreciable quantities of 18:1ω7 from its SCB. The SCB are heterotrophic and may contribute to the nitrogen budget of the host. The two symbiotic species studied here derive the bulk of their nutrition from conventional feeding but SCB make significant, additional contributions.

The force required to dislodge mussels from the substrate is known as attachment strength. This feature has been mostly studied in mytilids inhabiting the intertidal of consolidated rocky substrates, whereas it has been less studied in sedimentary substrates. The aim of this study was to evaluate the attachment strength and the number of byssal threads of Brachidontes rodriguezii in two sites with mobile substrates in San Antonio Bay, Argentina [Punta Verde (PV) and Punta Delgado (PD)]. PV has relatively higher current velocities and coarser grain size than PD. Along coastal line transects at two different levels of the mid-intertidal of each site, the attachment strength was measured. The number of byssal threads in collected mytilids and the weight of the sediment adhered to them were recorded in the lab. The attachment strength, the number of byssal threads and the sediment adhered to the byssus differed significantly between levels and sites. Mytilids from the mid-level of both sites where the density was relatively lower, had a significantly greater number of byssal threads and higher weight of sediment adhered. This study reveals that a high amount of coarse sediment adhered to the byssus affects the attachment strength of B. rodriguezii in ecosystems relative to unstable substrates. We underline the importance of mobile substrates in understanding attachment features (attachment strength and byssal threads) of mytilids in this unstable ecosystem.

Bioeroding sponges of the Cliona viridis species complex play a large role in carbonate cycling and reef health. In the present study we provide the first record and a description of a Mediterranean lineage of C. viridis (Schmidt, 1862) in the south-western Atlantic. Specimens were collected in Maricás Archipelago, Rio de Janeiro State in September 2010 by scuba diving at 10–12 m depth and deposited in the Porifera collection of Museu Nacional, Universidade Federal do Rio de Janeiro. Morphologically, the specimens presently examined are very similar to those described in the beta and gamma growth form from the Mediterranean. The Brazilian and Mediterranean specimens share large and irregular papillae over 2 cm in diameter, megasclere tylostyles up to 500 µm long and microsclere spirasters with up to five twists and 34 µm long. A Maximum Likelihood analysis of 28S rDNA of C. viridis, C. aprica, C. jullieni, C. schmidti and C. varians was performed for a genetic identification of the Brazilian specimens. The Brazilian material is phylogenetically closer to the Mediterranean C. viridis than to the Caribbean and Indian Ocean members of this species complex included in the present analysis. Our results suggest that C. viridis is a cryptogenic species with a distribution extending from the Mediterranean to the eastern Atlantic and in the SE Brazilian coast or further.

This one-year study investigated spatial and temporal variations in the abundance and biomass of the pink shrimp species, Farfantepenaeus paulensis and Farfantepenaeus brasiliensis, in the Conceição Lagoon, southern Brazil (September 2003–August 2004). The influence of salinity, water temperature, and rainfall on shrimp distribution was evaluated. Shrimps were caught monthly at three areas within the Conceição Lagoon (Canto, CA; Centro, CE; and Costa, CO). A total of 744 shrimps were sampled, with F. brasiliensis being the dominant species. The two penaeid species were present throughout the year and significant differences were observed between seasons, with F. paulensis being more abundant during the summer and F. brasiliensis in the autumn, suggesting differential migration timing to the sea, differences in recruitment time and an ontogenetic temporal partitioning. Farfantepenaeus paulensis exhibited a homogeneous spatial distribution, whereas F. brasiliensis was more abundant in CE and CO, suggesting that habitats in this coastal lagoon are heterogeneous. Among the abiotic factors, temperature and salinity seemed to be important variables in defining seasonal and spatial patterns, respectively, of the abundance of F. brasiliensis.

The relationship between the increase of the sea surface temperature observed off the Galician coast and the appearance of a tropical poikilotherm species Argonauta argo in these coasts is discussed. This is the first record of Argonautaargo in the north-west Iberian Peninsula. A female of this species was captured alive near the surface at dusk on 22 December 2000 in the Ria de Aldán (42°15′N–08°48′W). The specimen, a mature female of 70 mm mantle length and 96 mm shell diameter, died 36 hours after introduction in the tank.

Laboratory experiments with whole water-columns from shallow, eutrophic lakes repeatedly showed collapse of the predominant filamentous cyanobacteria. The collapse could be due to viral activity, from the evidence of electron microscopy of infected cyanobacterial cells and observed dynamics of virus-like particles. Burst-size effects on single-host single-virus dynamics was modelled for nutrient-replete growth of the cyanobacteria and fixed viral decay rate in the water column. The model combined previously published equations for nutrient-replete cyanobacterial growth and virus–host relationship. According to the model results, burst sizes greater than 200 to 400 virions per cell would result in host extinction, whereas lower numbers would allow coexistence, and even stable population densities of host and virus. High-nutrient status of the host cells might accommodate a large burst size. The ecological implication could be that burst-size increase accompanying a transition from phosphorus to light-limited cyanobacterial growth might destabilize the virus–host interaction and result in the population collapse observed in the experiments.

Upogebia deltura Leach and Upogebia stellata (Mont.) are both of common occurrence on the coasts of Devonshire and Cornwall, but in the adult stage they are not easily obtained, owing to their burrowing habits.The larvæ, however, are very common in the tow-nets, occurring throughout the year with the exception of the midwinter months, and are particularly plentiful from June to August.The two species are closely allied, and for some time it was believed that the differences between them might be merely sexual, and not specific (Bell 1853). They are now clearly recognised as separate and distinct species, and De Morgan (1910) has obtained males and females of both forms.Upogebia deltura Leach may be distinguished by its greater size, sometimes five or six inches in length when full-grown, as well as by its broad abdomen with soft abdominal pleura. The two joints of the chela on the first thoracic leg are almost equal in length.Upogebia stellata (Mont.) is an altogether smaller and more slender animal, seldom exceeding two and a half inches in length. The abdomen is narrower, and the fixed finger of the chela very much shorter than the dactylus. There is also a small point on the side of the carapace, just over the base of the second antenna, which has been established as a specific character by De Morgan (1910).In the living state the body of the animal is covered with orange-red spots (hence its name stellata), while Upogebia deltura Leach is of a uniform dirty cream colour.

A numerical model of the tides in the neighbourhood of Portland Bill (Pingree & Maddock, 1977; Maddock & Pingree, 1978) indicated that there was some asymmetry in the flood and ebb tidal patterns due to the effects of the Earth's rotation. Thus, in addition to the generation of vorticity due to the bottom frictional torque which becomes large in the high-velocity shoaling region near the promontory, vorticity is generated as columns of water with planetary vorticity are stretched or squashed as they move across water depth contours.

In order to examine the Portland Bill situation in more detail, a model was developed in plane polar coordinates (Pingree & Maddock, 1979). This model allowed the flow to be taken around the promontory without the numerical difficulties associated with corners in rectangular grid meshes and gives increased resolution near the headland where the major changes in tidal structure occur. The regular geometry of the polar model also allows the use of an idealized submarine topography and therefore changes in tidal flow due to imposed beach gradients can readily be examined.

The polar model has now been developed to derive the tidal flow around an idealised circular island surrounded by a uniformly sloping beach gradient. In the absence of effects due to the Earth's rotation the derived tidal structure and the associated patterns of residual flow possess twofold symmetry. In a rotating reference frame, however, some asymmetry in these flow patterns can be detected. In this paper some numerical results showing the hourly tidal streams around an island are derived.

A study has been made of the seasonal variations in the component acids of the lipid fractions of Balanus balanoides. The relative proportions of the polyenoic acids in the triglycerides drop sharply during the winter. They reach a minimum in the early spring and then gradually rise to a maximum in the late autumn. These changes are largely balanced by increases in the saturated acids, principally 16:0 and 18 :o.1 During the winter there is a marked decrease in the triglyceride to phospholipid ratio as the depot fats are mobilised as food reserves. The proportions of the polyethenoid acids in the phospholipids decline slowly during the winter and spring and attain their minimum in June-July. This fall is mainly counterbalanced by increases in the amounts of saturated acids, principally 14:0 and 16:0. It seems likely that the observed decreases in the polyenoic acids are brought about by selective utilization of these compounds as reserves during the winter when food is scarce and depot lipid has been depleted.

During an examination of the distribution and relationships of muscle receptor organs in the hermit crab, Pagurus bernhardus (Pilgrim, in preparation), it was found that not enough was known about the muscular anatomy of the animal for the experimental work to be described satisfactorily. This paper is therefore an account of the anatomy appropriate to a better understanding of the receptor organs. In the preparation of this account, it was necessary to examine the skeleton of the animal in great detail, since a knowledge of the relationships of especially the movable skeletal parts is basic for an understanding of the muscular system. The study also forms part of a series in which the comparative anatomy of the axial skeleto-muscular systems is examined in the Decapoda. This paper falls naturally into two parts, dealing respectively with the skeleton and the muscles. Although emphasis in this work is on the trunk anatomy of the last six segments of the thorax, it is necessary to extend observations beyond this region for certain interpretations.

Precopulatory mate guarding behaviour of the skeleton shrimp Caprella penantis is described. Moreover, the effects of body size, ownership and sex-ratio on mate guarding were examined experimentally in the laboratory. In the field population, the operational sex-ratio was male-biased. Guarding pairs, which were collected from the field, continued guarding for an average of 350 minutes in the laboratory, indicating that the normal guarding duration is approximately 10 hours. In this species, two guarding types were found: Type O and Type I-like. In Type O guarding, the male would fold the female into a horseshoe shape, whilst the male held the female parallel to him in Type I-like guarding. In the laboratory experiments, male body size was the most important factor affecting competition for a receptive female; ownership was the secondary factor. Guarding duration was prolonged when the sex-ratio was male-biased. Thus, the precopulatory mate guarding behaviour of C. penantis is influenced by several factors, such as body size, ownership and sex-ratio.

Ultrasonic treatment, a relatively less explored technology in water disinfection, was used to quantify the energy required for the destruction of larvae of barnacle Balanus amphitrite, which is a major marine fouling and a potential invasive organism. Since the power used and treatment time for disinfection are economically, and practically, the most important parameters, the energy required to pulverize the larvae into pieces ≤30 µm was determined as a function of the acoustic power density. The present investigation suggests that an ultrasonic system operating at 20 kHz and 0.0975 W/cm3 can effectively pulverize barnacle larvae having length (~440 µm) and breadth (~350 µm) within 45 seconds using 0.1 mJ/larva of pulverization energy. It was also observed that following pulverization of the larvae, the bacterial abundance increased and the rate of release of bacteria was dependent on power level and treatment time, which in turn decided the pulverization rate and hence the rate of release of bacteria.

In our previous paper (Fisher, Kon & Thompson, 1956) on Mollusca we pointed out that the Cephalopoda were so different from the other classes in vitamin A and carotenoid relationships that they would be more satisfactorily considered separately. We have so far analysed ten species of cephalopods and found vitamin A in all of them. The studies of previous investigators of vitamin A in these molluscs were confined to its function in the visual cycle and to its contribution to the vitamin A reserves of sperm whales feeding on cephalopods. The carotenoids of cephalopods have been given even less attention than vitamin A.

The distribution of sponges (Aplysilla sulfurea, Geodia cydonium and Petrosia ficiformis) and cnidarians (Astroides calycularis, Caryophyllia inornata and Leptosammia pruvoti) was investigated in a sublittoral cave with sulphur water springs from May 1993 to February 1994 at Capo Palinuro, on the south-western coast of Italy. Multi-factorial sampling designs were used to address: (1) the distribution and abundance of sponges and cnidarians on the vault and the sides of the cave at different distances from the entrance; (2) the distribution of cnidarians on the vault of the cave with respect to the type of substratum (sponges vs others) and distance from the entrance; and (3) whether abundances were correlated with the distance from the sulphur boundary and how this relationships changed moving from the outer to the inner part of the cave. All the sources of variation included in the study affected to some degree the distribution of organisms but patterns were not consistent among species. The abundance of A. calycularis decreased proceeding from the outer to the inner part of the cave, while the reverse was observed for L. pruvoti. Differences also occurred between the vault and the sides, A. calycularis and G. cydonium being completely absent on the vertical walls. Both A. calycularis and L. pruvoti were less abundant on sponges than on other types of substratum, but patterns changed in relation to the distance from the entrance. The abundance of L. pruvoti decreased close to the sulphur boundary, while the percentage cover of A. calycularis increased, but only at outer positions. Strong variability also occurred at the spatial scale of a few metres (between replicated areas) often overriding other patterns of distribution. Results have been discussed in terms of variability in the physico-chemical environment and in the outcome of interspecific interactions.

The European sea squirt, Ascidiella aspersa was first found as an alien species in 2008 from Funka Bay, Hokkaido, northern Japan, causing serious damage to the scallop aquaculture industry. We investigated A. aspersa on cultured scallops and larval occurrence from July 2010 to June 2014 to clarify life history traits and population dynamics, and consider the relation between the life history of A. aspersa and the process of scallop aquaculture. Larvae of A. aspersa were found from June to December, and recruitment on cultured scallops occurred mainly between July and October. The ascidians grew well and their weights increased until February. We found that 60–80% of A. aspersa that had settled in summer had eggs or sperm in autumn, and 90–100% of A. aspersa matured early the following summer. Maturity size in September was 17–20 mm as male, 22–24 mm as female. Scallops in Funka Bay are hung in the spring and harvested from winter to the next spring. Ascidiella aspersa settle as larvae in early summer, and grow well until winter, resulting in overgrowth on scallops in the harvest season. The linking of the process of scallop aquaculture and the life history of A. aspersa explains why this invasive ascidian has caused serious damage to the aquaculture industry in the bay. In comparison to the earlier descriptions of the native population, A. aspersa in Funka Bay has longer reproductive and growth periods, earlier initiation of reproduction, and possibly smaller maturity size.

On rocky shores of the British Isles and neighbouring regions of the North Atlantic coastline, the sporophyte of Laminaria hyperborea (Gunn) Foslie is the dominant member of most sublittoral algal communities. The bathymetric distribution, like the geographical distribution, is extensive; L. hyperborea is often dominant from extreme low water level of spring tides (E.L.W.S.) to depths of up to 32 m. The great changes in environment encountered by this species over this wide range of distribution would suggest a highly adaptable organism. Changes in size, rate of growth and growth pattern have indeed been recorded between plants at different latitudes and different depths. Plants from northerly waters generally are much larger with longer stipes and have a greater frond area (Kain, 1962; Bellamy & Whittick, 1968; Greenhager, 1958), although Kain (1963, 1967) points out that this is often due to greater longevity of individuals rather than greater growth rates. Increasing depth affects the density of distribution; the typical L. hyperborea forest becomes more sparse until an open community, called 'the park' when first recorded by Kitching in 1941, replaces the forest at about 15 m. The plants in the open community are smaller than those in the forest and have shorter stipes (Kain, 1962, 1966, and observations described in this communication). However, despite these changes in growth,, almost no morphological variation had been recorded prior to the present investigation. More recently there has been a report of a form L. hyperborea f. cucullata (Svendsen & Kain) from deep water and waters not subject to water movement with thin enlarged fronds and short stipes (Svendsen & Kain, 1971; Kain, 1971).

Egestion in the intertidal mud snail Hydrobia ulvae was investigated under conditions in which coprophagy did not occur, both in laboratory populations (comprising 11 experimental densities from 1000 to 120,000 ind m−2) and in a field population with an average density of 50,000 ind m−2 (24 test densities spanning the local range of <5000–>120,000 ind m−2). In contrast to an earlier study that suggested marked reduction in egestion rate in H. ventrosa as a consequence of interference competition, no such effect occurred in the natural population of H. ulvae, or in the experimental populations except at densities of at least 100,000 ind m−2. Neither did any significant increase in inactivity or movement off the experimental substrata occur with increasing density. These results are discussed in relation to resource limitation in natural densities of mud snails.

Saccular otolith shape and size were analysed for the first time in 120 adult individuals of D. vulgaris collected from two localities, the Bizerte and Ghar El Melh lagoons (north-east Tunisia). The objectives were (1) to examine the specific inter- and intra-individual variation in the otolith shape using elliptical Fourier analysis combined with measures of length (LO), width (WO) and area (AO); (2) to use the otolith shape and size analysis as a phenotypic-based approach to discriminate the stock structure of this species in the two localities to investigate whether they represent two separate stocks to inform on appropriate management procedures; and (3) to test for biases resulting from potential fluctuating asymmetry (FA) in the otolith size on the discrimination of stock structure. Discriminant function analysis performed with the normalized elliptical Fourier descriptors coefficients showed statistically significant differences (P < 0.0001) in the otolith contour shape, i.e. asymmetry, either between the left and right sides or between the same sides (left-left and right-right) within and among individuals of the two localities. Besides, a significant asymmetry (P < 0.05) was found in WO and AO among individuals within the Bizerte locality and in WO only within the Ghar El Melh locality. Moreover, significant FA was observed in the otolith size parameters among individuals of the two localities. This significant asymmetry detected in the otolith shape, as well as in the size due to FA, within and among individuals of D. vulgaris collected from the Bizerte and Ghar El Melh localities confirms that the two stocks could be discriminated from each other and should be managed separately. This asymmetry is discussed in light of the instability of development caused either by environmental stress associated with the variation in water temperature, salinity, depth, feeding conditions and pollutants that have led to abnormalities in the development of individuals or by the presence of poor living conditions for the larvae resulting from unfavourable environments.

To enable the study of population dynamics of wild animals the determination of the age, growth rate and maturity status of a sample of the individuals present is required; consequently, obtaining repeated accurate and precise total length (TL) measurements for individuals over time can be especially valuable. However, there are limited easily applied methods to ascertain the TL of large free-swimming fish, especially the largest extant species of fish, the whale shark (Rhincodon typus). This study expands on previous work and presents the results of a robust laser photogrammetry system developed to achieve accurate TL, pre-caudal length (PCL) and further morphometric measurements of whale sharks observed between 2009 and 2011 in seasonal feeding aggregations located in the Seychelles and Djibouti. Calculations for repeatability (r) indicated a high level of precision for the system with r approaching 1 for both TL and PCL, increasing further with the use of morphometric measurements. TL measurements of ‘straight sample sharks’ also provided geometric mean linear regression equations to enable the prediction of TL from defined morphological indices. Continuous validation of the system against objects of a fixed length also indicated a high level of accuracy for the method of measurement. We concluded that the laser photogrammetry system can be confidently employed to obtain accurate in-water TL, PCL and morphometric measurements for R. typus, with wide ranging implications and applications for the study of R. typus, and other large marine fauna.

The salinity tolerance of herring 9-ca 24 cm in length was found to lie between 6‰0 and 40–45‰0.

Determinations of changes in weight and blood concentration (by measurement of the freezing-point), when herring were transferred from one salinity to another, demonstrated that extensive changes occurred in the blood. Under these conditions the herring experienced and survived blood concentrations equivalent to salinites of 13–22·5‰. A recovery to near normal (δ0·95 ≡ 15·8‰) took place in all the salinities within the tolerance range.

Badly descaled herring in sea water showed large increases in blood concentration before death.

A study of the kidney of the herring indicated that the ability to withstand the low salinities for long periods probably rested in the high glomerular count of the kidney.

The importance of damage to the skin for survival is discussed in relation to tagging experiments.

The results are also discussed in relation to the evolution of the herring.