This study examined the role of predation in restricting early benthic phase (EBP) lobsters to shelter-providing substrata. In the field, the survival of animals provided with cover in the form of cobble and gravel substrata was significantly higher than unsheltered controls. Small benthic fish, particularly gobies Pomatoschistus minutus and rockling Ciliata mustela were the primary predators subtidally while crabs Carcinus maenus appeared to be the dominant intertidal predator. Predatory attack primarily occurred within minutes of the lobsters being deployed. The study reinforces the role played by predation in restricting EBP European lobsters to shelter-providing substrata.

In the present study a comparison of the otolith morphology of two species of parrotfish, family Scaridae, collected from the Red Sea coast of Egypt, is conducted to identify the most appropriate taxonomic characters that separate these species. Ontogenetic changes in the otoliths of the two scarid fishes become evident. In the otoliths of Chlorurus sordidus, the following characters are comparable in small-sized adult fishes: otolith width, otolith depth, mesial surface shape, lateral surface shape, shape of sulcus acusticus, column, rostrum and size of rostrum. The otoliths of young adults (GI) C. sordidus differ from the adult ones in 14 out of the 22 characteristics studied. In the otoliths of Hipposcarus harid, the following characters are comparable in small and large fish: otolith width, otolith depth, mesial and lateral surface shapes, shape of sulcus acusticus, rostrum and size of rostrum.

A method is described for investigating the reactions and spontaneous activity of two species of ascidian, Phallusia mammillata and Ascidiella aspersa, which does not disturb the animals unduly. The method can be used for obtaining graphic records of the so-called ‘reflexes’ of ascidians.

If due attention is paid to certain factors which affect the state ofthe animals, they can be made to respond to electrical stimuli applied to the outside of the test in a way which can be observed repeatedly in the same animal, in other animals of the same species and in at least two genera of ascidian.

Electrical stimuli applied to the test affect the excitable system of the whole animal in an all-or-nothing manner.

Response to graded electrical stimulation reveals a facilitation mechanism which gives enormous enhancement to the size and speed of response to the second of a close pair of effective stimuli. It is suggested that this mechanism is responsible for the production of the rapid squirt of the large sedentary ascidians.

A possible cause of the very rapid fatigue of ascidians to all kinds of stimulation is fatigue of the facilitation mechanism following a period of stimulation.

A parallel is drawn between the responses of Metridium and the responses of Phallusia and Ascidiella. The responses have some common features and the response mechanism appears to serve a similar purpose in the life of the animals.

We compared the reef fish assemblages of two habitats, coral reefs and coral communities (rocky substratum with coral colonies), in the Las Perlas Archipelago in Pacific Panama and attempted to determine associations with habitat variables. We used a modified Atlantic and Gulf Rapid Reef Assessment (AGRRA) survey to record fish species and quadrat transects to determine benthic composition. Multivariate non-parametric multi-dimensional scaling (MDS) ordinations were performed in PRIMER and univariate correlations were used to determine relationships. The reef fish of coral communities were significantly more diverse and species rich than those of coral reefs. The two habitats had significantly different species and size composition, but trophic and family groups overlapped between habitats. Topography, exposure, and the percentage cover of branching and massive corals correlated significantly with differences in fish parameters. The reef fish assemblages of this region appear to be determined more by the larger scale structural features that characterize the two habitats than by features that vary over small scales within the habitats.

Coastal areas, in general, are affected more and more by anthropogenic activities. Benthic macrofauna assemblages react to this disturbance and constitute, then, an effective biological tool to study the degree of contamination of the biotope. For this study three coastal sites, more or less exposed to anthropogenic activities but differing according to their opening to the sea, were studied. Sediments were sampled aboard a research vessel and using a 0.1 m2 Van Veen grab. Results show that Tunis bay and Dkhila coast, which are more open to the sea, appear more balanced on the trophic plan, and the biodiversity state is more satisfactory. However, Bizerte lagoon is closed, except for a limited communication with the sea via a narrow ship canal. So, the ecosystem presents some eutrophication signs and a great trophic imbalance in which carnivores largely dominate the benthic assemblages. In this situation, the herbivore chain is substituted by a microbial chain and only some opportunistic species can survive in these anoxic sediments related to the strong fluctuations of the environment factors during the year.

The structure of the microbial food web was studied in six estuary areas along the eastern Adriatic coast during March, July and October 2012. Limitation by phosphorus, not nitrogen, was a common feature for all studied estuaries. Heterotrophic bacteria and autotrophic picoplankton (APP) (particularly picoeukaryotes and Synechococcus) can reach notable abundances and biomasses, suggesting potential importance of the picoplankton community in P-limited estuarine environments. The main features of the microbial community structure in these environments included: (1) higher heterotrophic biomass in comparison to autotrophic biomass within the picoplankton community; (2) general domination of picoeukaryotes within the APP community, and increase of absolute and relative biomass of prokaryotic autotrophs (Prochlorococcus and Synechococcus) in the total APP in P-limited conditions; (3) domination of Synechococcus over Prochlorococcus biomass in all studied conditions, and common spatial distribution of these two groups of cyanobacteria, which was mostly determined by concentration of phosphorus; (4) relatively high contribution (about 50%) of LNA bacteria in the total bacterial abundance; and (5) relatively high contribution (about 33%) of heterotrophic pico-flagellates in the total flagellate abundance.

The relationship between the ability of brackish water invertebrates to regulate Na and K and the extent to which the radioactive fission product 137Cs can be accumulated has been studied.

The brackish water isopod Sphaeroma hookeri and the gastropod Potamopyrgus jenkinsi have been acclimatised to a wide range of sea-water dilutions. Unfed Sphaeroma can survive in sea-water concentrations of 100–2·5%, while Potamopyrgus can live fairly indefinitely in concentrations of 50–0·1%. Measurements of Na and K in the whole animals of both species and in the blood of Sphaeroma have been made. Salt movements are quite rapid and acclimatization to new media is achieved by both species in less than 10 h. Concentration factors for inactive K in particular increase to high values in the more dilute media.

Uptake of the isotopes 42K and 137Cs from solution has been examined in both species over a range of sea-water concentrations. All of the body K is exchangeable with 42K and in Sphaeroma exchange of 42K between the blood and tissues is so rapid that the body surface appears to be the limiting factor in the uptake of the isotope. Both species exchange 42K more rapidly in the higher concentrations of sea water and one reason for this may be the existence of an exchange diffusion component of exchange which increases as the salinity of the medium is raised. Indirect evidence suggests that the excretion of 42K in urine is probably not an important factor in exchange.

When exposed to water of low salinity specimens of Mytilus edulis L. keep their shell valves tightly closed; they do not gape periodically to test the external medium. Exchange of salts and water between the mantle cavity and the environment is thus minimized. Rising salinities are registered by diffusion of salts to the tentaculate portion of the inhalent siphon and not to any other portion of the mantle edge or to any more deeply located structures.

Nanoparticles have applications in a diverse range of products including medications, detergents, cosmetics, paint, sunscreen and electronics, with an economic worth projected to reach $2.5 trillion dollars in 2015. Research into the effects of manufactured nanomaterials on the environment, however, has failed to keep pace with the high volume of commercial production. Whereas a number of studies have examined the effects of nanoparticles on aquatic species, little work has focused on the way in which benthic marine species encounter, ingest and depurate these materials. The purpose of this study was to examine the ingestion and depuration of titania nanoparticles (anatase) by the blue mussel (Mytilus edulis) and the eastern oyster (Crassostrea virginica) during a spill scenario (an acute exposure to elevated concentrations). Bivalves were exposed to nanoparticles either incorporated into marine snow, an environmentally relevant medium for pollutants, or added directly to seawater at a concentration of 4.5 mg L−1 for 2 h. After feeding, the animals were transferred to filtered seawater and allowed to depurate. Faeces and tissues were collected at 0, 6, 24, 72 and 120 h, post-exposure, and analysed for concentrations of titanium by inductively coupled plasma-mass spectrometry. Results indicated that the capture and ingestion of titania nanoparticles by both species was not dependent on the method of delivery (incorporated into marine snow or freely suspended). Additionally, greater than 90% of the titania nanoparticles, on average, were eliminated from the tissues after 6 h, and only trace amounts remained after 72 h. These data demonstrate that mussels and oysters readily ingest titania nanoparticles, but rapidly depurate the material within hours of an acute exposure suggesting that little would be transferred to secondary consumers including humans. Further research is required to determine if other species of suspension-feeders handle titania nanoparticles in a manner similar to bivalves.

The manner in which mussels, Mytilus edulis, are presented to Carcinus maenas significantly influences crab prey-selection, resulting in different foraging behaviour. Handling techniques, breaking and handling times, percentage flesh eaten and prey value curves were compared when mussels of the following size-classes, 5–10, 10–15, 15–20, 20–25, 25–30 mm shell length, were presented singly and when they were presented as part of a group to crabs of 30–55 mm carapace width. When prey were presented singly, crabs used four size-specific opening techniques; outright crushing and directed crushing were used on smaller prey whilst boring and edge-chipping were used on larger, more resistant mussels. However, when mussels were presented as part of a group, boring and edge-chipping were never observed since larger mussels were not consumed. Handling time increased exponentially with mussel size irrespective of how mussels were presented, but, when crabs fed on mussels presented as part of a group, handling times tended to be shorter than when they fed on similar-sized mussels presented singly. The median percentage of flesh left uneaten in discarded shells ranged between 9.58 and 25.25% and was significantly greater than the median percentage of flesh left in the shells of mussels presented singly, which ranged between 4.66 and 14.70%. All resultant prey value curves were convex in shape, but the predicted optimal prey size altered with modifications in prey presentation. Similarly, when crabs of 30–65 mm carapace width were presented with groups of mussels comprised of different proportions of different sizes of mussels, size-class vulnerability was not fixed but altered significantly with the relative proportions in which these were presented. Thus, when the relative number of mussels in the smaller size groups were increased so was their vulnerability, indicating that prey size preference is flexible and not fixed.

Populations of heterotrophic bacteria from a marine fish-rearing unit were estimated using a spread plate technique. Bacterial populations in winter were relatively low compared with counts in summer when the maximum water temperature was recorded. Almost 600 isolates were examined, and found mostly to be Gram-negative rods. The bacterial populations consisted of a diverse array of taxa, and the variations in total numbers were due to relative changes in the abundance of these. There were nine groups isolated exclusively from the surface of turbot, including Alcaligenes faecalis, Bacillus firmus, Photobacterium Angustum, P. logei, Pseudomonas fluorescens and unidentified Gram-negative rods. In addition, pure culture growth of Alteromonas haloplanktis and unidentified Gram-negative, budding bacteria were isolated from within the lesions of moribund turbot.

Measurements of cephalothorax length were made on the females of five species of oceanic copepods for the period from January 1958 through August 1959. The seasonal length variations of the three species of Pleuromamma (P. piseki, P. abdominalis and P. xiphias) followed the cycle in total phytoplankton. Significant positive correlations were obtained between the mean lengths of P. abdominalis and P. piseki and the mean quantity of phytoplankton of the month previous to sampling, but there was no correlation between length and temperature.

The seasonal length variations of females of Haloptilus longicornis and Lucicutia flavicornis differed in pattern from that of the Pleuromamma species and no correlation was found between their mean lengths and the annual cycles of phytoplankton or temperature. These species may feed selectively on some possibly unmeasured fraction of the plankton or on particulate organic matter.

Previous work has shown that in waters with a wide temperature range there is a high negative correlation between length and temperature and no correlation between length and phytoplankton. In other regions with an intermediate temperature range the sizes of successive generations of copepods are correlated to almost equal degree with the temperature and the quantity of phytoplankton available during growth. In the Sargasso Sea, where there is a narrow temperature range but a definite seasonal cycle in total phytoplankton, the length variations of the Pleuromamma species are correlated with the phytoplankton cycle and not with temperature.

Experiments reported in a previous paper have indicated a considerable water loss by isolated preparations of the tube feet of Asterias rubens when ligatured in the protracted state. Because of its specialized structure, the podial diameter remains constant throughout the stepping cycle and this simplifies the procedure for measuring the surface area. Measurements of the internal hydrostatic pressure within the tube foot ampulla systems shows a maximum of about 30 cm water to be reached during the protraction phase of the stepping cycle, falling to nearly zero during the resting period. From these data it is possible to calculate a value for the permeability to water of the tube foot membrane, and such a value is compared with other membranes.

By measurement of the total area of protracted tube foot membrane exposed by the animal when supporting itself in sea water, it is possible to arrive at a figure for the total water loss by the water vascular system. For a 50 g animal this amounts to some 0·5 ml./h. Experiments involving blocking or extirpating the madreporite, and with isolated arms, make it extremely improbable that this loss could be made good from this route.

As alternative mechanisms, a slight hypertonicity due to the presence of excess potassium, or water movement as a direct consequence of the operation of an ion pump are discussed. In view of the hydrostatic pressure within the water vascular system the possibility of its functioning as a physiological kidney is also discussed. A possible alternative function for the madreporite is put forward.

The oxygen-carrying capacity of the blood of decapod crustaceans fluctuates widely. Salinity stress results in doubling of haemocyanin concentration within 24–48 h in Carcinus maenas (Boone & Schoeffeniels, 1979) while in the lobster, Homarus gammarus respiratory pigment levels are very low prior to and following moulting (Spoek, 1974). In general, however, the most important factor regulating haemocyanin concentration is nutritional state. Following starvation low values are recorded (Wieser, 1965; Uglow, 1969; Djangmah, 1970) and there are concomitant reductions in ventilation, oxygen consumption and cardiac output (Ansell, 1973; Marsden, Newell & Ahsanullah, 1973; Wallace, 1973). The interrelationships between these events are poorly understood.

Of the seven British species of Eurydice two are intertidal, three range successively from the immediate sublittoral to the edge of the continental shelf, and two predominate at the edge of and beyond the shelf. Most species have been recorded from the benthos and from surface plankton. E. affinis is recorded for the first time in Britain, among E. pulchra in intertidal sand in the Bristol Channel.

In a short paper presented to the 12th International Congress of Zoology in Lisbon in 1935, L. Fage described a new species of polychaete, Lumbriconereis flabellicola, living on a coral of the genus Flabellum in 450–600 m off Morocco (Fage, 1936) (PI. VIII, c). The dissolution of the calcareous coral skeleton to form a groove beneath the tube of the worm was well described and figured by Fage, who noted a report of a similar scleractinianpolychaete association from 489 m, off Spanish Sahara by Marenzeller (1904). Subsequently, palaeontologists have shown interest in the association described by Fage, but it has remained largely unknown to biologists, though mentioned in check lists (Hartman, 1951, 1959; Amoureux, 1973b) and in Grasse's Traite de Zoologie (Fauvel, 1959). The generic name Lumbrineris Blainville, 1828, has priority over Lumbriconereis Grube, 1840, and is now in general use.

Settlement behaviour of barnacle cyprids has been investigated extensively. There are two opposing tendencies. The cyprids settle gregariously over distances of several centimetres (Knight-Jones, 1953a, b; Knight-Jones & Stevenson, 1950; Knight-Jones & Crisp, 1953; Crisp & Meadows, 1962,1963). However, at closer range of a few millimetres they tend to space themselves out (Crisp, 1961; Knight-Jones & Moyse, 1961).

A first quantitative description of the suprabenthic fauna in a coarse sand community from the western English Channel is provided. One hundred and twenty species of Crustacea were collected in 22 suprabenthic sledge hauls collected throughout the year (1988–1989). Mysids and Amphipods dominated the fauna, among them Anchialina agilis (Sars), Gastrosaccus spp., Apherusa spp., Eusirus longipes Boeck, and Stenothoe marina (Bate) were the dominant species. Although most dominant species showed a vertically decreasing gradient of density from the lower net to the upper level of the sledge, the most abundant species, Apherusa spp., showed similar density at all four levels. The mean density at the four levels of the sledge did not differ significantly with the distance above the sediment. Species performed nocturnal vertical migrations: the densities of mysids were higher during the day than at night; conversely, the densities of amphipods and decapods were higher at night than during the day. The density and species richness showed high seasonal variation, from low values at the end of autumn and winter to high values in summer and the beginning of autumn. The results are compared with the available data on suprabenthic communities from the North Atlantic; this highlights (1) the lack of concentration of suprabenthic fauna towards the sediment on coarse sand, and (2) the highest abundance of the suprabenthic fauna from muddy substrata.

A local race of Idotea viridis from south-east Essex is described and its classification as /. viridis discussed. This animal is a nektonic form and so far has only been found in New England Creek in south-east Essex. The biology and post-embryonic development of this race is described. Quantitative samples were taken of the animals present in the creek in 1934, 1935 and 1936. I. viridis was rare in the first five months of the year; numbers rose to a maximum in late June and July and remained comparatively high until the end of October.

The number of young in the brood pouch is very variable. There is some evidence that the number of fertilized eggs was reduced by the expulsion of embryos before their development was complete. The newly hatched I viridisis described.

etmopterus spinax and etmopterus pusillus are captured in large quantities in some deep-water fisheries along the portuguese coast and are always discarded. specimens were collected from february 2003 to may 2004 from deep-water fisheries and classified as mature or immature. maturity ogives were fitted and size at first maturity estimated for each sex of each species. both species are late maturing, with the maturity sizes varying between 75% and 87% of the maximum observed sizes, depending on species and sex. for both species, females tended to mature at and grow to larger sizes than males. the late maturation of these deep-water shark species makes these populations extremely vulnerable to increasing fishing mortality.