The tendency under field conditions for settling Balanus balanoides larvae to space out from conspecific adults but not from adults of other species is reaffirmed. Explanations are advanced for the opposite conclusions reached recently by other workers. The general avoidance by B. balanoides larvae of settling on top of older barnacles is examined. It is suggested that there must be a strong inhibiting influence, so far unexplained.

The present paper deals with the results of investigations into certain phases in the life-history of the bivalve mollusc Tellina tenuis carried out during the autumn of 1926 and 1927.

Collections in the intertidal zone and below L.W.M., were made in a number of bays in the Cumbrae and neighbourhood, Kames Bay, Millport, being selected for intensive study.

In Kames Bay Tellina tenuis ranges from a little below H.W.M. to depths of about 4 fm. The maximum concentration of about 1000 per sq. m. is found at L.W.M. springs and the numbers decrease to zero at H.W.M. and 4 fm.

In Kames Bay the density of Tellina tenuis falls in a progressive manner from L.W.M. to H.W.M.

The size-frequency distribution shows a regular gradation from the lower to the higher levels. At L.W.M. and below individuals of small size predominate, while at H.W.M. they are proportionately few.

At higher levels growth is more rapid than at the lower levels.

The size-frequency curves and density of Tellina tenuis in the other bays at L.W.M. correspond with those of half-tide in Kames Bay.

The rate of growth may therefore be influenced by the density of population as well as by the habitat.

In all areas the 1926 brood predominates.

The Tellina tenuis population in Kames Bay seems to be composed of four year-groups, one of which is almost unrepresented. Collections from neighbouring bays indicate that older groups may be present.

The amount of young brood on the bottom seems to vary considerably from year to year, being large and small in alternate years.

The two closely related species, T. tenuis and T. fabula, are both plentiful in Kames Bay, but their range is not coincident.

Eipe sperms were found from May onwards and ova were rounding off in June.

Young Tellina tenuis, passing the 2-mm. sieve but retained by the 1-mm. sieve, were found in Kames Bay in August, chiefly below L.W.M., but in October plentifully distributed up to half-tide and in lesser numbers higher up the shore.

The food usually consists of vegetable detritus, but during the spring increase diatoms appear almost exclusively in the gut.

Sperm whale (Physeter macrocephalus) teeth were used to investigate whether variation in the chronological profiles of carbon and nitrogen stable isotope ratios along dentine growth layers could reflect differences in ontogenetic movements and/or dietary shifts in animals from different regions and sexes, as well as to show the differences in the isotopic environments experienced by these animals. Absolute isotopic ratios ranged from -14.1 to -11.0‰ for carbon and 10.8 to 18.1‰ for nitrogen, with the whale from the Indian Ocean, the two from the Mediterranean Sea and the female from the Azores presenting the most different median isotopic ratios. The Icelandic and the Indian Ocean males showed the expected decrease in δ13C around the age of ten, denoting male segregation from natal groups. For the latter, this was larger by almost twofold compared to other teeth, probably due to the much stronger latitudinal gradient in planktonic δ13C in the southern hemisphere. The Mediterranean Sea whales exhibited the lowest median δ15N values, probably reflecting the oligotrophy of this sea, while the male showed a marked change in isotopes around the age of 20 that could indicate a move to the eastern basin or a temporal change in basal isotopic signatures. The Atlantic females did not show a marked change in δ13C as expected since they stay in low latitudes throughout their lives. Stable isotope profiles in whale teeth can be used to investigate differences in the timings of ontogenetic movements and dietary history between individuals and sexes, and the biogeochemistry of different regions inhabited, and have the potential to allow inferences to be made about population substructure.

Abra alba and Abra tenuis are closely related marine bivalves. They both inhabit similar types of sandy-mud sediments but they prefer different localities. The smaller A. tenuis is found in a few scattered intertidal mudflats, whereas A. alba is more widely distributed and in great abundance in the coastal waters of north-west Europe. The latter can be found at any depth between low-water mark and 80 m (Tebble, 1966; Ansell, 1974) and often forms the dominant species of shallow water benthic communities.

The reproductive cycle of the two species has been studied and compared as a part of a wider ecological investigation. There is minimal literature concerning the reproduction of A. tenuis but A. alba has received a lot of attention, because it forms a major source of food for flatfish. However, most of the earlier investigations are confined to the time that spawning occurs with the evidence derived from either the time of the year that larvae appear in the plankton (Lebour, 1938; Jorgensen, 1946; Fosshagen, 1965; Muus, 1973; Rasmusen, 1973), or the time of the year that juveniles first appear in the bottom samples (Orton, 1924; Ford, 1925; Stephen, 1932). The inadequacy of such indirect methods has been discussed by Seed (1969,1975, 1976). Ansell (1974) derived the reproductive cycle of A. alba from seasonal changes in the biochemical composition. In the present investigation, histological techniques have been used, since they are considered to offer the most reliable information about the reproductive cycle (Seed, 1969, 1975, 1976).

The functions and structure of the pericardial glands (Keber's organ) of bivalves were reviewed by White (1942). The cells of this gland have been considered to have an excretory role and Grobben (1887) suggested that the cells of the pericardial gland could be compared with the chloragogen cells of annelids.

The seasonal maxima of occurrence of 23 species of mysids are examined; the numbers caught of a further four species were too small to draw any conclusions from. The evidence suggests that all species, except possibly two, aggregate; not enough information is available on Acanthomysis longicornis and Heteromysis fortnosa. The types of aggregations formed, whether population swarms or breeding aggregations, are unknown in 10 species. There is evidence of shoal and/or swarmformation in 12 species and of breeding aggregations in 7 species. All species known to form swarms live in shallow water; Leptomysis gracilis is the only species living in deep water that shows evidence of swarm formation. All other deep-water species aggregate, some for the purposes of breeding. Negative phototropism of individuals is suggested as a mechanism initiating aggregation of species in the bottom of deep-water basins. Reaction of one individual to another individual or groupof individuals (social behaviour) is considered necessary to intensify the initial degrees of aggregation and to maintain the integrity of shoals or breeding aggregations once formed. Parallels are drawn between aggregations of mysids and those of euphausiids.

Six mangrove forests in the urban region of Sydney, Australia, were examined to determine whether there were relationships between levels of human-induced damage and the structure of molluscan assemblages, the first stage in the validation of a technique for rapid assessment of the impacts of anthropogenic disturbance in urban mangroves. All six mangrove forests showed some damage but the amount varied considerably among and within each forest. Significant correlations between the levels of damage and abundance of different taxa, and changes in the structure of the molluscan assemblage along gradients of damage, suggest that indices based on measures of damage have the potential to provide a means for the rapid, wide scale evaluation of mangroves affected by impacts associated with human activities in urban areas.

The vent mussel Bathymodiolus puteoserpentis, a large vesicomyid clam and a smaller thyasirid were collected from an area of sediment subject to diffuse hydrothermal flow. The mussels live on the surface, the vesicomyids are partly buried and the thyasirids burrow in the sediment. The fine structure of the gills differs in the three bivalves. Bathymodiolus puteoserpentis hosts two types of bacterial symbiont, one methanotrophic, and another probably thiotrophic. The other two bivalves have single types of symbiont of different shapes. Stable isotope ratios of carbon and nitrogen indicate thiotrophy in the vesicomyid and thyasirid, but a predominance of methanotrophy in the mussel. This is the first time that such an assemblage has been found at a hydrothermal site on the Mid-Atlantic Ridge (MAR), with the different faunistic elements exploiting different energy resources.

The proximate biochemical composition and metabolic rates of ctenophores Mnemiopsis leidyi and Beroe ovata from the Black Sea were examined with respect to starvation conditions. Although organic matter content in B. ovata was two times higher than that of M. leidyi (2.51 ±0.53 and 1.14 ±0.17 mg g-1 of wet weight, respectively), these species did not significantly differ in their biochemical composition. In both species protein formed about 80% of the total organic matter, lipids amounted to about 10%. Carbohydrate and amino acids measured separately made up less than 6.5% of the total organic matter. Under experimental starvation (18 days at 16—18°C for B. ovata and 8 days at 12.4°C for M. leidyi), wet weights of both ctenophore species were reduced by 9.4% and 9.3% d-1, respectively. The rate of organic matter decrease was nearly two times lower than that of wet weight being on average 5.9% d-1 in M. leidyi and 5.5% d-1 in B. ovata. There was no trend in percentage of the four major biochemical categories with starvation time. The glycogen content in polysaccharides reached maximum values in freshly collected ctenophores (76.0 ±7.9% in B. ovata, and 86.6% in M. leidyi), but it was reduced substantially (34.4 ±2.7% in B. ovata and 18.3—28.8% in M. leidyi) with starvation. Monosaccharide content, expressed as a percentage of total carbohydrate, decreased from 39.9% to 13.5% in B. ovata, and from 45.8% to 14.3—23.2% in M. leidyi. The relationship between respiration rate (R) and wet weight (W) of individuals during the starvation can be expressed by power function R = R1 Wk (r2=0.85—0.94; P>0.001) for both ctenophore species. On average, k values were 0.95 and 0.83 in B. ovata and in M. leidyi, respectively. By the end of the starvation, metabolic rate per unit wet weight decreased by 33% in B. ovata and 46% in M. leidyi. Organic matter utilization was almost totally explained by respiration of ctenophores in the experiments and exceeded metabolic requirements of studied species by 11% and 15%, correspondingly. As compared with Mnemiopsis, Beroe has better tolerance to starvation which explains to some extent the success of the species survival during prolonged periods of food shortage in the Black Sea conditions.

Certain animals of the epifauna, because of their distribution over the bottom, are often difficult to sample quantitatively. They may occur as individuals widely dispersed over a large area, or they may be present in dense aggregations which themselves have a patchy distribution. In the past, workers have tried to estimate the numbers of such animals by the combined use of trawls and grabs of various types. The post-war development of underwater photography suggests that the camera will be a useful additional tool (e.g. Vevers, 1951, 1952). During the testing of an underwater camera from Aberdeen an opportunity was taken to compare the estimates of some of the larger epifauna from grab and trawl hauls with estimates derived from underwater photographs. The results are described in this paper.

1. A description is given of some measurements of the penetration of light into sea-water carried out near Plymouth in the autumn of 1925 by means of photo-electric cells, the current through the cell being, measured by a method, previously described, which is not affected by the motion of the ship.

2. The absorption coefficients found for off-shore waters down to 30 metres are smaller than the average of those found by several recent observers in various localities, but considerably larger than those found by Shelford and Gail for the deeper waters of Puget Sound. The coefficients tend.to increase with increase of depth, and are generally larger for in-shore waters. The clearest water, 20 miles out in the English Channel, gave an absorption coefficient 0-110 for the upper 10 metres, 0-117 for the second, and 0-133 for the third. This water, with glassy surface, transmitted 0-54% of the vertical illumination to 34-8 metres, 28-3% to 8-9 metres, at which depth a white disc was just visible, and 71-2% to 1-5 metres.

Juveniles of Patella spp. in Britain are shown to be easier to classify than adults, on shell morphology alone, because of a species-specific difference in number and arrangement of the post-larval mantle tentacles. The limpets can thus be clearly divided into three distinct spp.: P. vulgata Linn., 1758, P. aspera Roding, 1798, and P. depressa Pennant, 1777, which confirms recent evidence from gel-electrophoreric studies. As the limpet grows, this initial difference gives rise to many of the variables of shell shape and colour upon which adult identification is based. In the process, it can be influenced by environmental factors to the extent of producing confusing phenotypes such as those hitherto supposed to be hybrid or genetically transitional forms. The characters described suggest that, contrary to current opinion, P. aspera and P. depressa are related more closely to each other than to P. vulgata; they may also have some bearing on the species' success and distribution in the British Isles.

When littoral animals are exposed by the receding tide they are subjected to the environmental factors of what is essentially a terrestrial environment. Of these factors desiccation (see Davies, 1969) and temperature are of paramount importance. In winter the animals may be subject to a rapid change from the relatively high temperature of the sea to a very much lower air temperature. In summertime the opposite is true and the animals will spend the dry phase in air temperatures often far in excess of sea-water temperatures. The most important temperatures from an ecological point of view, however, are the body temperatures of the animals themselves. As shown by Southward (1958) this cannot be deduced from measurements of air temperatures, since the animals are subject to heating by absorption of solar radiant energy and this in turn may be mitigated by other environmental factors.

The identification of most soft-bodied hexacorals requires morphological and histological examinations of preserved specimens and experience for correct interpretation of the observed features. Poorly preserved or damaged material resulting from improper sampling complicates identification. In many cases the characteristics of the preserved specimens alone do not lead to satisfying results. Living specimens, however, exhibit numerous characteristics which would often allow identification, even in the field. However, most of these characteristics get lost during preservation. Modern techniques and advances in sampling methods allow the acquisition and preservation of a lot of information on the living animal and its habitat.

Using Chilean sea anemone species, it is demonstrated how the work with specimens in situ and in vivo can help with identification and reveal important morphological–taxonomical, biological, and ecological information. Whenever possible, this information should be part of species descriptions and should be used to create detailed, reliable, tabular identification keys for the laboratory and field. The examples illustrate the urgent need for modern, comparable re-descriptions. In most parts the protocol also applies to other soft-bodied hexacorals.

Predation of the barnacles Balanus balanoides and Elminius modestus by the common dog-whelk, Nucella lapillus was studied in the laboratory. Greater numbers of B. balanoides were taken as prey unless the whelks had been previously subjected to an extensive period of starvation.

Selective predation is discussed in the light of similar studies on Nucella and related predatory species. The effects of prey selection on the competitive interactions of the prey species are also considered.

The method of predatory attack involves either a drilling or a prizing technique. The latter is used predominantly when Nucella attacks E. modestus, whereas drilling is employed to a far greater extent when attacking B. balanoides. Attacks using the drilling technique are usually made at the occludent margins of the opercular valves.

Certain shallow-water embayments (< 1 m) along the Swedish west coast have recently been documented as highly productive areas for both infauna (Moller & Rosenberg, 1982, 1983) and mobile epifauna (Pihl & Rosenberg, 1982) as well as important nursery and feeding grounds for fish (Pihl, 1982; Evans, 1983). The present report, dealing with Nereis diversicolor O. F. Miiller, complements the earlier descriptions of recruitment, abundance and production of the dominant infauna species Mya arenaria L., Cardium (Cerastoderma) edule L. and Corophium volutator (Pallas) in these rather sheltered shallow areas in the archipelago of western Sweden.

The iron nutrition of Phaeodactylum tricornutum (Bohlin) has been studied, and the limitation of growth because of iron deficiency demonstrated. Evidence is presented suggesting the ability of the organism to utilize paniculate iron and to adjust its utilization of iron in the presence of a continuing deficiency. One effect of lack of iron is a reduction in the degree of pigmentation and the ability of added iron to restore the pigmentation. Figures are presented showing the iron content per cell, and a comparison with other organisms suggests that the brackishwater P. tricornutum may be atypical when compared with coastal and oceanic members of the marine phytoplankton.

In recent years several workers have postulated the occurrence in a number of coastal animals of endogenous behaviour and physiological rhythms of semilunar periodicity (see Naylor, 1982). However, only a few of these long term rhythms have been demonstrated as free-running cyclical behaviour over long periods of time in constant conditions. For example, the supra-littoral amphipod Talitrus saltator (Montagu) has been shown to express semilunar variations in daily locomotor activity over three cycles of neap/spring tides during 46 days in constant conditions in the laboratory (Williams, 1979). In contrast, in the mid-shore sand-beach isopod E. pulchra (Leach) semilunar variations in swimming behaviour (Fish & Fish, 1972; Alheit & Naylor, 1976) and of respiration (Hastings, 1981a) have so far been demonstrated only in isopods collected at various stages of the neaps/springs cycle of tides and recorded for a few days in the laboratory. It, therefore, still remains to confirm unequivocally in Eurydice, and in many other forms, which appear to show semilunar periodicity, that such rhythmicity is expressed as a free-running rhythm over long periods of time in constant conditions.

Ucides cordatus is the most commercially important mangrove crab in Brazil. In spite of its economic importance, there are few studies of its reproduction, in particular the female reproductive system. The present study describes the histology and histochemistry of the spermathecae of U. cordatus. Adult females were caught monthly from July 2004 through June 2005, at Iguape, State of São Paulo. The crabs were anaesthetized, and their spermathecae removed and fixed in Davidson's fluid, following the histological routine for paraffin. The slides were stained with HE, xylidine Ponceau, PAS, alcian blue (pH 1.0 and 2.5), Sudan black B and picrosirius-haematoxylin. Histologically, the spermathecae possesses a capsule of conjunctive tissue, rich in collagen fibres, which surrounds the secretory columnar epithelium. In the lumen, individual sperm packets are not observed; the spermatophores are intermixed with the seminal fluid and secretions of the spermathecae itself. A large proportion of the free spermatozoids and spermatophores are arranged in homogeneous masses in the proximal part of the spermathecae. The secretion produced by the columnar epithelium appears to promote the movement of the gametes to the fertilization chamber, in a ventral position, allowing fertilization of the oocytes. Histochemically, the secretion produced by the columnar epithelium was strongly positive for neutral polysaccharides, positive for acid polysaccharides, and weakly positive for proteins and lipids. This secretion forms a glycoprotein matrix which is associated with maintenance of the spermatophores, which can remain stored for long periods.

Comparisons of the behaviour of herring (Clupea harengus L.) were made in the light and dark by means of an infra-red sensitive TV system and video recording. Herring which were schooling in the light became less active in the dark, their swimming speed decreased, they tended to disperse and the proportion of gliding compared with swimming fish increased. Herring which were not schooling in the light increased their swimming speed in the dark.

When subjected to transient sound stimuli herring made fast-startle responses. The proportion of fish responding was lower in the dark. The directionality of the response (the proportion turning away from the sound source) was the same in the light and dark suggesting there was no visual component in the response.

The proportion of swimming and gliding fish affected both response rate and directionality. Gliding fish tended to have a higher response rate and better directionality than swimming fish, although this depended on the conditions of the experiment. The configuration of the body of swimming fish at the onset of a transient sound stimulus was important. Of the swimming fish, over 80% of the responders turned away from the direction in which the tip of the caudal fin was pointing at the onset of the stimulus. Gliding fish are in a better ‘neutral’ posture to initiate a startle response and to turn away from the sound source.

Comparisons of awareness (sensory thresholds) in the light and dark using startle responses are complicated by differences in the numbers of gliding and swimming fish.