Two Red Sea immigrant fish species, Fistularia commersoni (Fistularidae) and Sphyraena flavicauda (Sphyraenidae), are reported for the first time from the Anatolian coast (Turkey) and for the second time from the Mediterranean Sea. Occurrence of Lagocephalus suezensis (Tetraodontidae) at the southern Turkish coast is substantiated and a new record of this species in the Aegean Sea is presented.

The earlier investigations (Raymont, Austin & Linford, 1964, 1966) on the brackish-water, semi-planktonic mysid, Neomysis integer (Leach), dealt with the total protein, lipid and carbohydrate fractions, together with chitin and ash. Results showed that a relatively high protein content (mean 71 % dry weight) was typical of Neomysis; the protein showed very little change throughout the year. Lipid was much lower and more variable (7–15%; mean 13 % dry weight), and carbohydrate was especially low (mean 2.5 % dry weight). Ash and chitin together amounted to some 14 % dry weight (Raymont et al., 1966).

In the north-east Atlantic, the dominant reef-framework forming coral species, Lophelia pertusa and Madrepora oculata, form a symbiotic association with the polychaete worm Eunice norvegica. The polychaete–coral symbiosis was studied by visually observing and photographing live animals in aquaria over many months and using time-lapse video under infra-red lighting to record activity patterns. The polychaetes act as reef aggregating agents by joining coral colonies and enhancing the development of reef patches in deep water. The symbiosis was investigated using samples collected from a relatively shallow site in a Norwegian fjord and from a deeper open ocean site in the Porcupine Seabight. The potential functional roles of this symbiosis are considered. The reef aggregating behaviour of the polychaete symbiont allied with the ability of the coral host to anastomose its branches, the polychaete tubes and debris falling onto the reef structure will help to shift the balance between reef growth and (bio)erosion in favour of growth.

Observations in the field, and in the laboratory, of littoral fishes of south-west England during the period 1978–80 have shown that the three blenniid species found with any frequency on the shore constitute an important link in food chains. The occurrence, age, habitat and diet of Blennius (Lipophrys) pholis L., Coryphoblennius galerita L., and Parablennius gattorugine Brunnich have been considered; B. pholis was by far the most common of the three, with very few P. gattorugine being found intertidally. Of the latter, only age groups 0, 1 and 2 were represented in the littoral populations, whereas in the truly littoral species age groups 0–10 were found for B. pholis and 0–6 for C. galerita. Measurements of growth rates for the three species have been compared with growth rates of B. pholis and C. galerita at other sites, and a similar treatment has been afforded to dietary constituents. A discussion of the possible competition for food and refuge between the three species, and with other littoral teleosts, concludes that highly efficient partitioning of resources reduces competition to a minimum, with the exception of abundant food items which are (in any case) probably underexploited.

In Branchiomma vesiculosum decrease in light intensity causes the animal to contract and withdraw into its tube. A decrease, never an increase, in illumination is the effective stimulus. When repeatedly stimulated the animals quickly become adapted to intensity changes and no longer respond.

The minimal effective intensity change has been determined for a range of intensities. ΔI/I is found to increase in low light intensities, and to be fairly constant in intensities over 50 lux. The animals are least sensitive to red light; sensitivity increases in shorter wave-lengths.

The following investigations were carried out in order to test the validity of the oft-recurring statement to the effect that “burrowing organisms live under fresh-water conditions during low tide in estuaries.” This type of statement is usually made in respect to organisms which live in the sand or mud of estuaries in which, at low tide, a stream of fresh, water passes over the ground in which the organisms are buried.

I have not been able to find any references to show that work has ever been done on this subject with the idea of determining the actual salinity of the water held by such sand. Therefore I carried out the following experiments to try to find if data could be procured which would be sufficiently consistent to lead to any conclusions.

An investigation of the rate of growth in Marine Invertebrates was begun in 1911, and a large amount of material the age of which is known has now been collected from various sources. The particular objects of this research are: (1) to establish the age of common marine invertebrates, (2) to determine the minimum age at which these forms begin to breed, (3) to examine the rate of growth at different seasons of the year and under different conditions, (4) to investigate the fecundity of different forms so far as possible, and (5) to collect the scattered literature on these subjects.

Neutral lipid classes were analysed in the livers, muscles and sera of Deania, Centroscymnus, Squalus and Prionace. All three squaloid sharks contained triglycerides and alkyldiacylglycerols and the two deep sea squaloids contained additionally hydrocarbons. Prionace contained triglycerides and hydrocarbons but no alkyldiacylglycerols. For a given species the class compositions of the lipids were similar in liver, muscle and serum, except that serum contained additionally cholesteryl esters and wax esters. Cholesteryl esters in Squalus serum were rich in oleic acid whereas wax esters were very rich in polyunsaturated fatty acids. Squalus serum contained a major and a minor lipoprotein species both of which transport all four neutral lipids in serum. It is concluded that, with the exception of cholesteryl and wax esters in serum, neutral lipids are distributed between shark tissues by a mechanism that is relatively non-specific with respect to lipid class.

To examine density-dependent effects on growth in Cerastoderma edule (L.) (Bivalvia), growth rates of individual cockles established by chance at high and low densities on the same intertidal mudflat in two different years (1984 and 1989) were compared. Two-year-old cockles occurring at high densities (>2000 individuals m-2 in 1984) attained mean lengths from 16.1 to 18.8 mm on the lower shore at the end of their third growing season, while low-density cockles (<50 individuals m-2 in 1989) of the same age reached mean lengths in the range of26.5 to 30.3mm. In terms of individual weight the difference between cockles from the two periods was even more striking, as the flesh ash-free dry-weight of a cockle from 1984 constituted only 7% of that from a 1989 cockle. During both periods growth in cockles increased with the duration of tidal submersion, but the interannual growth differences exceeded by far the effect of differences in submersion time.

Samples of animal and plant plankton were added to sea water in glass vessels and the subsequent changes in the phosphate content of the water were followed.

The breakdown of the zooplankton was very rapid and more phosphate was set free than had originally been added as plankton. The balance was produced from dissolved organic phosphorus compounds in the water. The breakdown of phytoplankton showed a short time lag and only a part of the phosphorus added was set free as phosphate.

Profiles of bottoms near the shore of the Isle of Man and two areas of Scotland are described, together with the vertical distribution of species of Laminariaceae. Laminaria digitata dominates over a narrow zone near lowwater springs. Unstable bottoms, providing they are sheltered enough to be habitable, support mainly L. saccharina. Stable bottoms of either boulders or solid rock support L. saccharina when sheltered (by topography or depth) from wave action and L. hyperborea when exposed. Near Port Erin, Isle of Man, the downward penetration of L. hyperborea on exposed rocks and boulders is limited by an as yet unknown factor which might possibly be associated with a slope of more than to the horizontal.

Saccorhiza polyschides (Lightf.) Batt. is a laminarian alga found in the sublittoral region. It is widely distributed around the shores of the British Isles and is particularly common on the south west coast of Ireland. A puzzling aspect of the distribution of the species in Southern Ireland is its absence from Lough Ine, in County Cork.

Between April 2002 and April 2005, 210 estuarine dolphin groups were sighted, with 58 animals individually identified. Fifteen dolphins were photo-identified just once, while only two animals were sighted in 15 different months. Some individuals showed long-term residence (more than 3 y). Residence rates showed heterogeneity in the dolphin's permanence of the estuary, with 60% of the individuals with low numbers (<10) and only 7% showing high values for residence (maximum=45.9). Continued resightings of some dolphins support the regular use of the study area by the animals, despite some individuals that, after a long time without resightings were registered again. Individual range analysis showed that dolphins shared the same common area, the Caravelas River Estuary. A marked fluctuation in the number of photo-identified dolphins was observed in the study area, revealed by the high number of individuals with just a few resightings. The majority of the dolphins (60%) present a yearly residence pattern, as observed in other areas, suggesting that a few individuals show high fidelity for the area, while many other dolphins move constantly between different areas for unknown reasons.

Investigations on larval nematodes in herring revealed that Anisakis sp. larvae occurred in the body cavity of 34 % of 5646 juvenile and adult herring examined; and that the infection increased with increase in fish length (age) and varied with the locality, being greater in herring caught nearer to the British coasts. The effect of temperature and salt concentrations on the survival of the larvae and the public health hazards of the larvae were discussed.

INTRODUCTION

Dinoflagellates have often been held responsible for a large part of the phosphorescence of the surface waters of the sea. In temperate waters, dinoflagellates are seldom the most abundant constituents of the phytoplankton, and until recently little experimental evidence has been available to support this assertion. Until recently there have been few careful attempts to determine which particular species of dinoflagellates are luminescent, or to relate total luminescence to numbers of dinoflagellates present.

It has increasingly been recognized that organisms can interfere with parasitic free-living stages, preventing them from infecting their specified host and thus reducing infection levels. This common phenomenon in freshwater and terrestrial systems has been termed the ‘dilution effect’ and, so far, is poorly studied in marine systems. Ten common intertidal organisms found in the Dutch Wadden Sea (North Sea) were tested to establish their effects on the free-living cercarial stages of the trematode parasite Himasthla elongata. Most species tested resulted in a significant reduction in cercariae over a 3 hr time period. The amphipod Gammarus marinus removed 100% of the cercariae, while other effective diluters were Crangon crangon (93%), Sargassum muticum (87%), Semibalanus balanoides (71%), Crassostrea gigas (67%), Hemigrapsus takanoi (>54%), Crassostrea gigas shells (44%) and Idotea balthica (24%). In contrast, mixed shells (Cerastoderma edule, Mytilus edulis, Ensis americanus and Littorina littorea) and Fucus versiculosus had no significant effect. These results suggest that dilution effects are widespread in the trematode of H. elongata, with potentially strong effects on its population dynamics.

The inability of Lima Mans Gmelin to enclose the soft tissues of the body within the shell is correlated with the development of other defensive adaptations.

L, Mans can automize entire pallial tentacles or parts of tentacles which subsequently secrete a viscous mucus distasteful to potential predators. Autotomy takes place at transverse septa along the length of the tentacles and mucus is secreted by epidermal gland cells.

The transverse septa of the tentacles also regulate the hydrostatic pressure of blood within the tentacles and permit the performance of complex locomotory movements. It is suggested that the septa were originally developed to serve this locomotory function and, secondarily, function as planes of weakness at which autotomy may take place.

L. Mans builds protective nests. The nests are constructed by burrowing into a gravel substratum and consolidating the walls of the burrow with byssal threads. When disturbed in the nest L. Mans performs locomotory movements which lead to enlargement of the nest. If the nest is broken the locomotory activities result in free swimming followed by attempts to burrow into the substratum to form a new nest. It is unlikely that L. Mans swims freely in nature except when displaced from the nest.

Introduction

Most bivalve molluscs react to unfavourable stimuli by retracting the soft parts of the body within the shell valves and contracting the adductor muscles to oppose the valve margins. In Lima hians Gmelin the mantle margin, even with its numerous long tentacles fully retracted, cannot be accommodated within the shell valves. In this paper the inability of L. hians to retract the soft parts within the valves is correlated with two types of defensive behaviour: (i) the secretion of mucus by the tentacles of the mantle margin and the autotomy of these tentacles, and (ii) the interrelated activities of swimming and nest-building.

The study of growth rates in the prosobranch snails Hydrobia ulvae and H. ventrosa under field conditions showed that growth rate of snails infected by different trematode species is species-specific. Trematodes from the families Microphallidae and Heterophyidae cause gigantic growth whereas species from families Notocotylidae and Bunocotylidae have no effect on growth rate. This discrepancy is attributed to the different pathogenicity of the parasites. However, under experimental conditions with different host population densities the effect of infection by Bunocotyle progenetica effect varies from a tendency to stunt the growth (under high density) to a significant increase in growth rate (under low density). The effect of Himasthla sp. (Echinostomatidae) was shown to be population-specific. These findings agree with a previously reported hypothesis that the growth response of trematode-infected snails depends (among other things) on supplement of host-parasite system with food. Trematode infection caused parasitic castration in all studied host-parasite combinations. It is argued that the phenomenon of gigantism in infected snails is a consequence of the reduced sexual ability of the host. The correlation between snail growth rate and penis size of infected males was negative. The correlation between growth rate and penis size was not found in uninfected snails from the same age group

Deep-sea holothurians of the genus Paroriza (Family Synallactidae) have often been observed or photographed in pairs or triplets. Observations of tracks on the sea floor suggest that pairs may remain together for some time. We explored the reasons for pairing in a study of reproductive condition and diet, using animals collected by trawl from the bathyal and abyssal north-east Atlantic and by manned submersible from the bathyal slope of the Bahamas. Both species of Paroriza studied were found to be simultaneous hermaphrodites producing yolky oocytes. Oocytes of Paroriza pollens were about 350μm in diameter, whereas those of P. prouhoi were up to 450μm. Examination of oocyte size-frequency distributions suggests that reproduction is continuous for both species. Neither mean oocyte size, nor shape of the oocyte size-frequency distribution differed significantly between paired and unpaired P. pallens collected during the same season. These deposit-feeding holothurians appear to take food from the nutrient-rich phytodetrital layers on the surface of the sediment. Because their food resources are probably not patchy on small scales, the observed pairs are not likely to be feeding aggregations. We hypothesize that pairing increases the likelihood of external fertilization and that spawning in these species may be induced at any time by the presence of a conspecific rather than by seasonal cues.

The nutrient requirements of many algae are well documented, with most algae being found to need only one or two vitamins. In the case of their predators, only a handful of microinvertebrates have had their diets and even fewer their vitamin requirements denned. Thus, any progress in this field together with the mode of nutrient uptake, must lead to a better understanding of the component-transfer in the food chain.

Brachionus plicatilis Müller has been reported to require vitamin B12 (Droop & Scott, 1978). The work described in this paper sought first, to confirm this and then to establish the mode of uptake. The alga Brachiomonas submarina var. pulsifera Droop was used to investigate the first of these questions as the writer had previous experience with it in steady-state energetics work. The alga Dunaliella SMBA Strain 246 was used to examine the mode of uptake by the rotifer since this had also been found to be a good food organism. The possibilities considered were uptake: (a) via the algal cell; (b) directly from solution; (c) a combination of both. Mode of vitamin B12 uptake is of particular interest as it may be representative of the pathway of many of the rotifer's water soluble micronutrients.

Before considering the influence of the vitamin on Brachionus investigations were made into the relationship between the vitamin and the two food-algae. It has already been established that Brachiomonas has a definite requirement (Droop, 1961) and Dunaliella no requirement for vitamin B12 (Turner, 1979). It was of interest to see if they took-up the vitamin in the manner shown by Monochrysts, a B12 requirer, and Phaeodactylum a non-requirer (Droop, 1968).