It has been suggested in Part IV of these contributions that the larger diameter of centric diatom cells met with in collections made in the oceans in the lower latitudes might be caused in part by the relatively greater grazing known to take place in these areas (Steemann-Nielsen, 1962; Lohmann, 1912). Eight series of experiments were therefore carried out to determine any effect that might be attributed to animals grazing on populations of centric marine diatoms.

Submarine cliffs are typically crowded with sessile organisms, most of which are ultimately exported downwards. Here we report a 24 month study of benthic fauna dropping from such cliffs at sites of differing cliff angle and flow rates at Lough Hyne Marine Nature Reserve, Co. Cork, Ireland. The magnitude of ‘fall out’ material collected in capture nets was highly seasonal and composed of sessile and mobile elements. Sponges, ascidians, cnidarians, polychaetes, bryozoans and barnacles dominated the sessile forms. The remainder (mobile fauna) were scavengers and predators such as asteroid echinoderms, gastropod molluscs and malacostracan crustaceans. These were probably migrants targeting fallen sessile organisms. ‘Fall out’ material (including mobile forms) increased between May and August in both years. This increase in ‘fall out’ material was correlated with wrasse abundance at the cliffs (with a one month lag period). The activities of the wrasse on the cliffs (feeding, nest building and territory defence) were considered responsible for the majority of ‘fall out’ material, with natural mortality and the activity of other large mobile organisms (e.g. crustaceans) also being implicated. Current flow rate and cliff profile were important in amount of ‘fall out’ material collected. In low current situations export of fallen material was vertical, while both horizontal and vertical export was associated with moderate to high current environments. Higher ‘fall out’ was associated with overhanging than vertical cliff surfaces. The ‘fall out’ of marine organisms in low current situations is likely to provide an important source of nutrition in close proximity to the cliff, in an otherwise impoverished soft sediment habitat. However, in high current areas material will be exported some distance from the source, with final settlement again occurring in soft sediment habitats (as current speed decreases).

Amiantis umbonella is distributed throughout the coast of the northern Persian Gulf. This study of 893 clams provides data on reproduction, growth and production for the period April 2007 to March 2008 from two transects along the Bandar Abbas coast. Histological preparations showed six stages of gametogenic development: resting stage (Stage 0), early active (Stage I), late active (Stage II), ripe (Stage III), partially spawned (Stage IV) and spent (Stage V). The specimens were gonochoric and showed synchronized spawning. The reproductive cycle commenced in September and finished in March with one major spawning event in January which correlated with lower sea temperature. Von Bertalanffy growth parameters for the sample were asymptotic length (L∞) = 58–62 mm, growth constant (k) = 0.28–0.29 yr−1 and length zero (t0) = –0.48 –0.47. The mean annual clam abundance, mean biomass and production were 10 individuals. m−2, 5.7 g shell free dry weight (SFDW) m−2 and 0.495 g SFDW m−2 yr−1, respectively.

Aora spinicornis Afonso is recorded for the first time from the British Isles. Two species of Aora, A. gracilis (Bate) and A. spinicornis Afonso are now known from these waters. A. typica Krøyer, long considered a British and Irish species, is actually known only from the Southern Hemisphere. Figures and diagnoses of both species are provided together with a key to their identification.

Introduction

Lincoln (1979) records one species of Aora Kreyer from British and Irish waters. Due to an oversight (Lincoln, personal communication) he overlooked the paper by Myers (1973) (although listed in the bibliography) and attributed the single species to A. typica Krøyer, a species actually known only from the Southern Ocean between 20° S and 50° S (see Myers & Moore, 1983 which also includes a key to the world species). Two species of Aora are now known from the British Isles: A gracilis (Bate) which is widely distributed, and A. spinicornis Afonso, recently discovered in Lough Hyne, Co. Cork, and herein reported for the first time from these waters. This latter species has a Lusitanian distribution (Azores, Canaries, Mediterranean) and may occur in south-western England and Wales, but has been confused previously with A.gracilis (Bate). Both species have been described and figured by Myers (1973, 1982) and do not require further detailed analysis. However, since both species are now known to occur in these waters and are not both treated by Lincoln's widely used monograph, the two species are figured here as entire specimens (for details of appendages including mouthparts see Myers, 1982) and briefly diagnosed, and a key is provided to facilitate their identification by British and Irish workers.

Ceratothoa collaris is reported for the first time outside its known geographical range, which was restricted to north-western African coasts (from Senegal to Tunisia). Many specimens of different developmental stages were collected off the Lebanese coast in the eastern Mediterranean. In addition to an update of the geographical range, synonymy and host specificity, an accurate redescription of the species is given on the basis of new and old materials.

The diet and feeding habits of the sharpsnout seabream, Diplodus puntazzo, from the Gulf of Gabès were investigated using stomach contents of 490 specimens ranging from 12.6 cm to 26.1 cm total length in size and from 29.95 g to 230.83 g in weight collected from commercial catches between April 2008 and March 2009. Of the total number of examined stomachs, 279 were empty (%VI = 56.94). This percentage varied significantly with months, attaining a maximum in spring (74.88%) and a minimum in autumn (37.38%). Eight major taxa were identified (Plantae, Spongia, Tunicata, Echinodermata, Crustacea, Annelida, Mollusca and Teleostei) in stomach contents of D. puntazzo. Plants were the most important food source, constituting 89.88% of the total Index of relative importance. The other groups, such as teleosts, molluscs, crustaceans and annelids represented accessory food. Significant differences in diet were observed in relation to season. Plants were the most important food source item in all seasons, especially during the autumn. The estimation of trophic level gave an average of 2.57 ± 0.2 for the whole population of D. puntazzo in the Gulf of Gabès. Based on the composition of its diet, this species may be considered as an omnivorous fish with a preference for vegetable material, and showing specialist feeding strategy.

Elemental composition and ontogenic change patterns of Sr and Ca were examined in conger eel, Conger myriaster, otoliths. Accumulations of the major elements of seawater, K, Mg, and Na, into otoliths were smaller than the accumulations of 19 other minor elements whose concentrations were determined. Strontium content and Sr:Ca ratios in the otolith fluctuated during the life history transect at 100 to 200 μm from the core of the otolith, indicating a period of metamorphosis. Changes in Sr content and Sr:Ca ratios may be associated with internal physiological factors such as metamorphosis in the early developmental stage in the conger eel.

The seasonal variation of the inshore fish assemblage of Anegada Bay, North Patagonia, Argentina is described here. Three areas were seasonally sampled from 2007 to 2009 by means of a gang of bottom gill-nets. We found 21 coastal fish species, but species richness and fish number and weight changed throughout the year. The six species classified as dominant have national and regional value for artisanal and recreational fishing and were responsible for the seasonal variation in the fish assemblage. Both cluster and non-metric multidimensional scaling analyses based on fish number and fish weight indicated two major sample groups encompassing spring and summer (the warmer seasons) and autumn and winter (the colder seasons). The fish assemblage had higher species richness, dominance and abundance during the warmer seasons than during the colder seasons in the same years and at the same sites. Water temperature was the main environmental factor structuring the fish assemblage in Anegada Bay. We suggest that partial breeding migration toward the bay during warmer months could explain the seasonal pattern observed. Nevertheless, variation in temperature conditions agreed well with the pattern of seasonal changes, leading to an interaction between abiotic and biotic influences in determining the variability in this seasonal fish assemblage. We conclude that an understanding of species temporal and spatial patterns in areas of high ecological and economic value, as exemplified by Anegada Bay, are essential for the implementation of a management approach oriented toward ecosystem sustainability.

Freezing-point measurements were made of blood samples taken from specimens of the marine wood-boring isopod Limnoria that had been exposed to sea water of various salinities for 2-3 days. Most of the work was done with L. (L.) tripunctata Menzies, but some preliminary experiements were carried out with L. (L.) lignorum (Rathke) and L. (L.) quadripunctata Holthuis.

It was found that the freezing point of the blood averaged 0·17°C above that of the external of medium in both hyp- and hyperosmotic environments. In the absence of any obvious factor which could explain this discrepancy, it is assumed that Limnoria has a certain degree of control over its blood concentrations.

Further experiments showed that the blood concentration fell as soon as the animal was introduced to the reduced salinity and levelled off at the hyperosmotic value within a few hours. There was some evidence of a periodicity in the osmoregulation.

The possible energetics of osmoregulation in Limnoria are discussed and it is concluded that the amount of energy utilized in the process is unlikely to make any significant inroad into the energy resources available for boring activity.

As well as acting as a neurotransmitter, serotonin is also involved in morphogenetic signalling during crucial phases of many developmental and regenerative processes such as cleavage, migration and differentiation. Echinoderms display nerve-dependent regenerative phenomena and serotonin is one of the main neural regulatory factors that have been identified in them. The present work was designed to investigate the broad-spectrum involvement of this molecule in echinoderm regeneration, focusing on arm regeneration in the crinoid Antedon mediterranea. We carried out specific in vivo exposure experiments to selected anti-serotonergic drugs (a synthesis inhibitor: parachlorophenylalanine and a receptor antagonist: methiothepin) and explored their possible effects on arm regeneration. Drug exposure appeared to affect regeneration, causing a general delay of regenerative growth and several histological anomalies mainly in the muscles of the stump. In addition, exposure to the antagonist produced a marked reduction of cell proliferation in both the regenerate and the stump. Our results provide further evidence that serotonin has wider functions than those related to interneuronal communication and that it may be a critical signalling molecule in the main processes of regeneration such as proliferation, morphogenesis and differentiation.

An objection often raised to experiments on tissues treated with artificial solutions and isolated from nervous control is that results obtained under such highly abnormal conditions can be of no real value. This criticism arises essentially from a misconception as to the aim of the experiments in question, but it is encountered so frequently that it may not be out of place to consider briefly why it is necessary for the physiologist who would learn something of the more intimate mechanism of the cell to work with tissues under artificial conditions.

Luminescent polynoids emit light from their elytra. These structures are arranged in two longitudinal rows covering most or all of the dorsal surface of the worm. Light emission is evoked by stimulation and appears as a single flash or series of flashes (Nicol, 1953, 1957).

When a polynoid is subjected to tactile stimulation, scales anterior and posterior to the stimulated region emit flashes. The response is a reflex, the excitatory pathways of which involve peripheral receptors, nerve cord, and a peripheral ganglion in each elytrum on the efferent side of the arc (Bonhomme, 1942; Nicol, 1954).

The calanoid copepod Temora longiornis (Müller) has sub-cuticular secretory glands located on both the body and swimming legs. The glands are tri-cellular, consisting of a secretory cell (producing a proteinaceous secretion) opening through a cuticular pore, a collar cell surrounding the neck of the secretory cell, and a duct cell which lines the pore opening. The possible function of the secretion is discussed.

The measurements recorded for marine algæ of various groups show that the reaction of the sap is in most cases almost neutral, and in no case is the sap of the pronounced acid character met with in many land plants. This being so it follows that the enzymes concerned in the metabolism of these algæ must be quite different from those which effect corresponding changes in land plants, as may be seen on referring to the optimum pH values for various enzymes quoted in the writer's previous paper on the reaction of plant cells (1922).

A small orange-coloured Enchytraeid Oligochaete has been known for some years to occur fairly abundantly in certain sheltered parts of the shore on the Cumbraes. It is also generally present, though scarce, on exposed parts of the shore. Hitherto it has been confounded with other species of Lumbricillus, but is now described as a new species.

Sponges are rare in extreme environments, and very little is known about their adaptations to such settings. Evidence from two species in a marine-derived midwater stratified crater lake on Satonda Island (Sumbawa, Indonesia) suggests their production of gemmules (resting bodies), a rare trait in marine sponges but common in freshwater forms, may be a survival mechanism in the lake's harsh environment. With its epilimnion hydrochemistry—characterized by changing alkalinity, salinity, and O2 levels over the region's wet and dry seasons—the lake sustains only a few marine macroscopic organisms, among them the suberitid sponges Protosuberites lacustris comb. nov. and Suberites sp. (Hadromerida: Suberitida). Both species belong to the same group as sponges reported from other marine-derived lakes with strongly varying and extreme environmental (especially chemical) parameters. The morphological characters, taxonomic position, ecological adaptations, environmental conditions, and biota associated with the sponges in this ecologically unique site are presented here.

Gold has been determined in six marine sponges by neutron activation analysis. The amounts found (1·8–12·6 × 10−8 g/g dry sponge) are higher than would be expected from measurements of the distribution of 198Au between sea-water and dead sponge samples.

Many attempts have been made to devise methods for concentrating gold from sea water, but none of them are commercially viable. Recent work has shown that gold can be concentrated by adsorption or absorption on certain artificial polymers (Hummel, 1957; Bowen, unpublished). This note describes some measurements of the accumulation of gold by marine sponges whose scleroprotein structure resembles some of the artificial polymers employed.

Two new species of zoarcid fish, Ophthalmolycus eastmani sp. nov., and Ophthalmolycus polylepis sp. nov. are described from specimens collected from the Bellingshausen Sea and Gerlache Strait, Southern Ocean, at depths of 1837 and 1056 m. Ophthalmolycus eastmani can be distinguished from its congeners by the following combination of characters: two posterior nasal pores; epidermal prickles on lips and snout; gill slit extending ventrally to the lower margin of the pectoral fin base; vertebrae asymmetrical 26 − 27 + 91 − 92 = 117 − 118; dorsal fin rays 111–113; dorsal fin origin associated with vertebra 6, with no free pterygiophores; pectoral fin rays 17–18; two postorbital pores; lateral line with ventral and mediolateral branches; scales extending anteriorly to just anterior to the anal fin origin; six branchiostegal rays; oral valve nearly reaching the anterior edge of vomer; palatine teeth in two rows anteriorly; 3–5 pseudobranch filaments; two well developed pyloric caeca; pelvic fin and vomerine teeth present. Ophthalmolycus polylepis can be distinguished from its congeners by the following combination of characters: two posterior nasal pores; epidermal prickles on lips; gill slit extending ventrally just to below mid-pectoral fin base; interorbital pore present; two postorbital pores; lateral line triple with ventral, mediolateral and dorsolateral branches; scales extending anteriorly to predorsal area, abdomen, pelvic fins base, and pectoral fins base and axil; vertebrae asymmetrical 22 + 76; dorsal fin origin associated with vertebra 5; pectoral fin rays 18; six branchiostegal rays; oral valve overlapping the anterior edge of vomer; two rows of palatine teeth anteriorly; two vestigial pyloric caeca and 2 pseudobranch filaments; pelvic fin and vomerine teeth present. A key to the species of Ophthalmolycus is provided.

The light energy emitted in a flash by single elytra of two polynoid worms has been measured, viz. Acholoë astericola and Lagisca extenuata. Maximal emission occurs at 515 mμ. Mean values for light intensity per flash from 1 elytrum are: Lagisca, 1·8 × 10−10 μJ/cm2 receptor surface at I m ; Acholoë, I·II × 10−8 μJ/cm2 receptor surface at I m. The light emitted in I flash by a single photocyte of Lagisca is 0·12 × 10−12 μJ/cm2 receptor surface at I m. It is estimated that the light from I elytrum of Lagisca could be seen by the dark-adapted human eye at 1·2 m in air.