Epipelic diatoms represented the dominant microphy tobenthos on the intertidal mudflats of the Severn Estuary, south-western Britain. Algal biomass (measured as chlorophyll a concentration) varied over a seasonal cycle and was strongly correlated with sediment shear strength and critical shear stress and therefore with position on the shore. High levels of diatom biomass were positively correlated with the concentration of colloidal carbohydrate within the surface sediments. The critical shear strength for incipient erosion was significantly correlated with position on the shore (moisture content) and with both chlorophyll a and colloidal carbohydrate, the latter being the best biochemical predictor for the incipient erosion threshold. The range of stress required to cause incipient erosion varied from 1.0 to 8.0 N m-2, with the sediment increasing in resistance landwards. Two-way analysis of variance using both moisture content and colloidal carbohydrate as variables explained the stability of the sediment better than individual pair-wise comparisons.

Demersal fishes on the continental rise and slope were sampled by trawl, baited trap and a baited camera. Seventy-one different species were trawled, but only 18 species approached baits. At rise soundings (4100 m to 2250 m) Coryphaenoides (Nematonurus) armatus was dominant at baits and comprised 41·5% of the trawl catch. On the slope (<2250 m) Synaphobranchus kaupi was dominant at baits and comprised 32·7% of the trawl catch. At 1500–2501 m Antimora rostrata competed at baits and comprised 5–10% of trawl catches. At 1500–1650 m Centroscymnus coelolepis also consumed baits but was not captured by trawl. For C. (N.) armatus abundance was proportional to tarr2 (where tarr= arrival time), demonstrating that arrival time of the first fish at baits provides an estimate of population density. Maximum estimated abundance at 2897 m was 877 km-2, more than five times the abundance on the abyssal plain. Halosauropsis macrochir, Lepidion eques, Coryphaenoides guentheri, Gadiculus argenteus and Coryphaenoides rupestris were important in trawl samples but absent or rare at baits.

Concentrations of lead in the soft tissues of the deposit-feeding bivalve Scrobicularia plana have been compared with the physicochemical characteristics of sediments in 20 estuaries in southern and western England and one in north-west France. The results indicate that the biological availability of lead in the sediment is controlled mainly by the concentration of iron, and that the concentration of lead in the bivalve may be predicted from the Pb/Fe ratio in 1 N hydrochloric acid extracts of surface sediments.

The vertical distribution of chlorophyll in the sea generally shows a maximum concentration at a depth which may vary from at or just below the surface, to near or below the bottom of the euphoric zone. The easiest distributions to explain are those where the maximum chlorophyll concentration is at or very near the surface. These are found when a population is photosynthesizing actively during the first stages of an outburst, and the distribution corresponds roughly with the change with depth of the photosynthetic rate (Steele, 1957). However, these form a small proportion of observations, probably because outbursts are usually restricted to comparatively short periods of time. The more usual distributions show a maximum in the chlorophyll concentrations well below the surface and below the depth of maximum photosynthesis.

The lowest photon flux density of photosynthetically active radiation at which O2-evolving marine photolithotrophs appear to be able to grow is some 10 nmol photon m−2 s−1, while marine non-O2-evolvers can grow at 4 nmol photon m−2 s−1, in both cases with the photon flux density averaged over the 24 hour L:D cycle. Constraints on the ability to grow at very low fluxes of photosynthetically active radiation fall into three categories. Category one includes essential processes whose efficiency is independent of the rate of energy input, but whose catalysts show phylogenetic variation leading to different energy costs for a given process in different taxa, e.g. light-harvesting complexes, RUBISCO and probably in the sensitivity of PsII to photodamage. The second category comprises essential processes whose efficiency decreases with decreasing energy input rate as a result of back-reactions independent of the energy input rate, e.g. charge recombination following charge separation by PsII and short-circuit H+ fluxes across the thylakoid membrane which decrease the fraction of pumped H+ which can be used in adenosine diphosphate phosphorylation. Category two also includes that component of protein turnover which cannot be related to replacement of polypeptides which were incorrectly assembled following uncorrected errors of transcription or translation, or which were damaged by processes whose rate increases with increasing energy input rate such as photodamage to PsII. The third category includes only O2-dependent damage to the D1 protein of PsII whose rate increases with a decreasing incident flux of photosynthetically active radiation. Processes in categories two and three are most likely to impose the lower limit on the photon flux density which can support photolithotrophic growth. The available literature, mainly on organisms which are not adapted to growth at very low photon flux densities, suggests that three major limitations (charge recombination in PsII, H+ leakage and slippage, and protein turnover) can individually impose lower limits in excess of 20 nmol photon m−2 s−1 on photolithotrophic growth. Furthermore, these three limitations are interactive, so that considering all three processes acting in series leads to an even higher predicted lower photon flux density limit for photolithotrophic growth.

A photochemical reactor, using a medium power mercury arc lamp for oxidation of organic matter in sea water, is described. The decomposition of some known compounds in distilled water and in sea water, using a 380 W lamp, was followed. First order kinetics with rate constants in the range 0·2–4·0 h−1 were observed. All the nitrogen compounds tested, including urea and some of its derivatives, were oxidized quantitatively. Breakdown of phosphorus compounds was rapid, but polyphosphate esters yielded polyphosphate ion which was only slowly hydrolysed to reactive orthophosphate. If polyphosphate is to be determined, hydrolysis by heating with acid should follow the irradiation. Some samples of English Channel water contained 0·02-0–05 fig-axom P/1. as organic polyphosphate.

This paper presents results on the distribution, abundance, and size of Lophelia pertusa coral reefs in mid-Norway (62°30&;–65°30&;N) as compiled from own investigations, earlier scientific reports, reports from fishery surveys and fishermen. Detailed bathymetrical mapping covering an area of ∼600 km2 along the Halten gas-pipeline, and two nearby areas across the shelf revealed 70 Lophelia reefs. In general, the reefs occurred close to breaks and escarpments. High densities of up to nine reefs per km2 were found in areas with a rugged seabed topography and with a slope >0·6°. These seabed features have probably positive influence on the transport and concentration of food particles and thus control the local distribution of Lophelia. The area covered by individual reefs varied between 1230 m2 and 37,310 m2 with a mean of 5628 m2. The height of the reefs was positively correlated with the area. Reefs <10,000 m2 had a circular outline, while larger reefs were elongate, aligned parallel to the depth contours. Along the pipeline the average density of Lophelia reefs was 0·09 km−2 which indicates that the total number of reefs is ∼6300, covering ∼35 km2 within the whole study area.

Estuaries perform a crucial role in the life-cycle of many fish (Cronin & Mansueti, 1971; Day, Blaber & Wallace, 1981; Dando, 1984). They provide a migratory route for anadromous and catadromous species and an environment in which the limited number of true estuarine teleosts spend the whole of their life cycle. The upper reaches are colonized by certain freshwater species while the lower regions are penetrated by some marine fish during high tide. However, many marine teleosts enter and remain within estuaries for a period of time, often in very large numbers and particularly during the early part of life (see e.g. Gunter, 1938, 1961, 1967; Huddart & Arthur, 1971; van den Broek, 1980; Blaber & Blaber, 1980; Potter et al. 1983; Whitfield, 1983). The recognition that estuaries act as important nursery areas for certain teleosts by providing such features as a rich food source and protection from predation (see e.g. Pearcy & Richards, 1962] Jacquaz, Able & Leggett, 1977; Blaber & Blaber, 1980) has led to such species being referred to as estuarine-dependent (see e.g. McHugh, 1976; Beal, 1980; Fortier & Leggett, 1982).

1. The food of the bottom fauna of the Plymouth fishing-grounds, at an average depth of 27 fathoms, lias been investigated. This has been done by the examination of the stomach contents of animals, both fresh and preserved, and supplemented by observation of living animals in aquaria.

2. The sources of food have been discussed. Attention is drawn to the importance in these regions, not so much of organic detritus, which is considered by Petersen and Blegvad to be the only important ultimate supply in Danish waters, but of the contributions from the plankton itself and from the considerable microflora and microfauna inhabiting the bottom deposits.

3. Petersen and Boysen Jensen have stated that the detritus present in Danish waters can be traced almost entirely to the annual decay of the Zostera beds. The area occupied by Zostera in Plymouth waters is very smalLin.comparison with that in the Danish fjords and the detritus found here, though considerable in quantity, and in appearance much as described by Petersen, must originate largely from other sources. The possible1 sources of origin apart from land-sources are the coastal Algse and the plankton. A consideration of the annual production of each of these' suggests that the plankton is the more important factor.

4. Blegvad has classified marine animals according to their food into Herbivores, Carnivores, and Detritus-eaters, but this classification does not fit the conditions in the area here studied and is not therefore of general application. Herbivores are absent from these grounds, and few of the animals could be described strictly as detritus-eaters. The animals fall into the following natural groups, according to their food and the mode and location of their feeding:—

A. Carnivores—Animals which feed mainly upon other animals, either living or as carrion.

B. Suspension-feeders—Animals which feed by selecting from the surrounding water the suspended micro-organisms and detritus.

C. Deposit-feeders—Animals which feed upon the detritus deposited on the bottom, together with its associated micro-organisms.

5. Following the preceding classification the food of the common animals of the Plymouth fishing-grounds has been described briefly.

The eye of the larval herring has only single cones in the retina. They are characteristic in ultrastructure at this stage with a striated outer segment, an ellipsoid packed with mitochondria and with a connecting cilium at the junction. Cones are gradually added at the margin of the retina as the larva grows. There are no retinomotor responses in the larval eye. It has, however, adult characteristics in the postero-ventral area temporalis (though it is undifferentiated at this stage) with its blindly ending anterior pocket and in the falciform process closing off a trough-shaped ‘ancillary’ eye.

At metamorphosis (30–40 mm) a number of changes occur: the area differentiates, twin cones and the rods appear, the latter perhaps developing from cells originating in the bipolar layer and migrating to a position inside the external limiting membrane. Retinomotor pigment migration and change in length of the cone myoids also develop when the eye is subjected to changing light intensities, the threshold being 1.0–0.01 me (metre candles).

In the adult eye the fully developed retina has an area temporalis packed with single cones giving high acuity on the main visual axis, which is in the upperfore direction. The lens presumably gives accommodation by postero-ventral movement brought about by a postero-dorsal suspensory ‘ligament’ and a ventroanterior falciform process. This process also delimits the area and divides off the ‘ancillary’ eye from the main retina.

Over the whole range of development the cone ellipsoids grow in diameter from 2 to 12 μ and decrease in density correspondingly.

Further study of the phenomenon of gregariousness during settlement, demonstrated in the oyster Ostrea edulis (Cole & Knight-Jones, 1949; Knight-Jones, 1951) and the barnacle Elminius modestus (Knight-Jones & Stephenson, 1950), seemed to require laboratory experiments, for which a viviparous animal with a brief, lecithotrophic, pelagic stage appeared to be needed.

between 1997 and 2003, there were 2088 natural predations by white sharks (carcharodon carcharias) on cape fur seals (arctocephalus pusillus pusillus) and 121 strikes on towed seal-shaped decoys were documented from observation vessels at seal island, south africa. white sharks at seal island appear to selectively target lone, incoming young of the year cape fur seals at or near the surface. most attacks lasted <1 min and consisted of a single breach, with predatory success rate decreasing rapidly with increasing duration and number of subsequent breaches. a white shark predatory ethogram, composed of four phases and 20 behavioural units, is presented, including four varieties of initial strike and 11 subsequent behaviour units not previously defined in the literature. behaviour units scored from 210 predatory attacks revealed that, for both successful and unsuccessful attacks, polaris breach was the most commonly employed initial strike, while surface lunge was the most frequent second event, closely followed by lateral snap. examination of video footage, still images, and tooth impressions in decoys indicated that white sharks at seal island bite prey obliquely using their anterolateral teeth via a sudden lateral snap of the jaws and not perpendicularly with their anterior teeth, as previously supposed. analysis of white shark upper tooth morphology and spacing suggest the reversed intermediate teeth of white sharks occur at the strongest part of the jaw and produce the largest wound. white shark predatory success at seal island is greatest (55%) within one hour of sunrise and decreases rapidly with increasing ambient light; the sharks cease active predation on seals when success rate drops to ±40%; this is the first evidence of cessation of foraging at unproductive times by any predatory fish. at seal island, white shark predatory success is significantly lower at locations where frequency of predation is highest, suggesting that white sharks may launch suboptimal strikes in areas of greatest intraspecific competition; this is the first evidence of social influence on predation in any elasmobranch. idiosyncratic predatory behaviours and elevated success rates of known individual white sharks at seal island suggest some degree of trial-and-error learning. a hypothetical decision tree is proposed that models predatory behaviour of white sharks attacking cape fur seals at the surface.

Populations of the common dog-whelk Nucella lapillus (L.) are declining or have already disappeared at many sites on rocky shores around the United Kingdom (Bryan et al. 1986). There is conclusive evidence that this is caused mainly by tributyltin (TBT) compounds leached from ships' antifouling paints (Bryan et al. 1987). These compounds impose male sexual characters (or imposex) on female N. lapillus. Other stenoglossan gastropods including Nassarius obsoletus Say (Smith, 1981a) and Ocenebra erinacea (L.) (Féral & Gall, 1982) are similarly affected by TBT. The intensity of expression of imposex in N. lapillus can generally be related to the sea water concentration of TBT. The appearance of a small penis and the partial development of a vas deferens first occurs at TBT concentrations below 0.5 ng/1 (as tin), although reproduction appears to be unaffected at this level. At 1–2 ng Sn/1 penis size is markedly increased and in some females proliferation of vas deferens tissue overgrows the genital papilla, thus sterilizing the animal. At slightly higher concentrations virtually all females become sterilized and at around 10 ng Sn/1 oogenesis is suppressed and spermatogenesis initiated (Gibbs, Pascoe & Burt, 1988). Since development is direct and there is no planktonic stage, N. lapillus has a very limited capacity for dispersion: thus the sterilization of females heralds the almost certain decline of so affected populations (Gibbs & Bryan, 1986).

Vertical hauls between surface and 45 metres depth were made with a measuring net, throughout 1934, at a position 5 miles S.W. of Plymouth Breakwater in circa 50 metres depth of water.

The phytoplankton organisms were counted and also assessed from their content of plant pigments.

A close relation was found between numbers of diatoms and their pigment contents after making allowance for the small size of three species.

The phosphorus content of the phytoplankton was estimated on several occasions.

The zooplankton organisms per cubic metre of sea were counted and estimations were made of their phosphorus content.

The diatom population differed from that found in 1933, in which year the spring outburst was shorter but more intense, the sporadic summer outbursts were more intense, the autumn one lasted longer; and more phosphate was utilised by the plants during the first half of the year.

Submersible observations have been made on‘ patches’ of the deep-water coral Lophelia pertusa (L.) occurring on Rockall Bank, north-east Atlantic. It is suggested that an initial colony gives rise to a ring of younger colonies. These in turn give rise to further rings of colonies, thus enlarging the ‘patch’. The transition from stage to stage depends on portions of living colonies, weakened by clionid sponge attacks, breaking off and falling away from the colony so providing the substrate for the development of later colonies, thus enabling lateral increase in the size of the ‘patch’ to take place.

Nautilus macromphalus Sowerby when freshly caught was close to neutral buoyancy having a weight in sea water of about 0–2% of its weight in air. The animals without their shells varied considerably in density but the volume of the shell was an approximately constant fraction of the total volume of the whole animal and whole animals were brought approximately to the same density by havingmore or less liquid inside the chambers of the shell. About 80 % of the gas space in the shell was used to support the weight of the shell itself in sea water.In an adult animal the centre of buoyancy was found to be about 6 mm above the centre of gravity, which made the animal very stable in its natural swimming position, a couple of about 350 g. cm being required to turn it through 90°. The pearly partsof the chamber walls were impermeable to sea water but the chalky and horny siphuncular tubes joining the septal necks were very porous. The most newly formed tenor so chambers were the only ones to contain liquids in appreciable volume and theydid this in diminishing amounts from the newest to the oldest. The watery liquids found within the chambers were always hypotonic to sea water and sometimes markedly so; they contained principally sodium and chloride ions. One animal was in the process of forming a new chamber, this incomplete chamber was completely full of liquidwith an osmolarity close to that of sea water but differing in composition from seawater.

The observations to be recorded here have been carried out primarily for the purpose of clarifying the taxonomic position and naming of the small organism previously known as Chromulina pusilla Butcher. This had been shown (Manton, 1959a) to possess the pigments and fine structure appropriate to a position in or near the Chlorophyceae but quite inappropriate to a position within the Chrysophyceae to which the genus Chromulina properly belongs. Before selecting a new generic name, it was highly desirable to make some comparative electron microscopical observations on authentically named material of appropriate kinds since the fallibility of the light microscope for study of organisms of this order of size (1–3µ) had been all too clearly exposed. A search was therefore made for a representative or representatives of the only genus of green flagellates known to us from the literature to possess a single posteriorly directed flagellum, namely Pedinomonas.

Although a great deal is known about methods for the culture of commercially important bivalve larvae (see, for example, Loosanoff & Davis, 1963; Walne, 1964, 1966) little information is available on the biochemical changes that take place during larval development.

Collyer (1957) determined the glycogen content of several batches of newly released larvae of Ostrea edulis and found that viability was not related to the initial glycogen content. Millar & Scott (1967) showed that lipid was the major energy reserve used during starvation by newly released O. edulis larvae. Recently Helm, Holland & Stevenson (1973) have shown that the initial growth rate of newly released O. edulis can be positively correlated with the lipid content of the larvae on liberation.

The present paper describes the biochemical changes that occur during larval development, metamorphosis and early spat growth of O. edulis. In addition, short-term starvation experiments were carried out to determine whether protein, lipid or carbohydrate serves as the main energy reserve during each phase of development.

This paper reviews some specific studies of cetacean life history energetics over the past 20–30 y that include one of the largest species, the baleen fin whale, Balaenoptera physalus, the medium-sized odontocete long-finned pilot whale, Globicephala melas, and one of the smallest marine odontocetes, the harbour porpoise, Phocoena phocoena. Attention is drawn to the decrease in longevity with size and the differences in biological parameters that reflect this and affect life history strategy and energy utilization. Data from the past whaling industry in Iceland for fin whales, the Faroese ‘grindedrap’ for pilot whales, and by-catches as well as some live captive studies for harbour porpoise have been used. The studies demonstrate how information can be gathered to compile energy budgets for individuals, relying on carcase measurement and analysis, dietary investigations, biochemical analyses of tissues, and general life history studies including reproduction; as well as from monitoring living animals. The individual examples presented show how food energy storage in the form of fat can be variously important in insulation in the smallest species to controlling reproductive efficiency in large migratory species. The paper concludes by noting that an understanding of energy use in the individual can be an important input in multi-species ecosystem modelling.

A new coccolithophorid, Crystallolitkus hyalinus, was described with the help of electron micrographs by Gaarder & Markali in 1956 from preserved material in which the cells lacked the appendages. From temporary cultures set up from our September 1957 sea-water samples a coccolithophorid was isolated which appeared, under the light microscope, very similar to this newly described coccolithophorid but which possessed, as does the genus Chrysochromulina, a coning haptonema in addition to the two flagella. Electron micrographs, taken for us by Prof. I. Manton, have shown that the holococcoliths from our organism are identical in structure with those from the Crystallolithus hyalinus (cf. PL I, and Gaarder and Markali, 1956, pi. I).