Twelve strains of psychrophilic, marine pseudomonads which grew readily on nitrate or a mixture ofamino acids, were tested for their content of the enzymes glutamine 2-oxoglutarate amino transferase (GOGAT) and glutamic dehydrogenase (GDH). All strains contained GOGAT activity when grown on nitrate and GDH when grown on amino acids. In all strains tested the synthesis of GOGAT was repressed by growth on amino acids and derepressed by growth on nitrate.

Seasonal changes in cold-tolerance of Balanusbalanoides are correlated with the seasonal changes in free glycerol level in the body parts of adult barnacles and with the degree of unsaturation (iodine number) of the body lipids. Glycerol levels and iodine values were highest in the winter when the barnacles were most cold-tolerant and lowest in the summer when they were least tolerant. There was no correlation between the seasonal changes in cold-tolerance and seasonal changes in free amino acid level or triglyceride: total lipid ratio.

Under laboratory conditions barnacles kept without food at 5 °C over the summer to winter period became cold-tolerant and had high, winter levels of glycerol and high iodine values. Winter barnacles kept at shore temperatures and fed Anemia nauplii until mid-summer lost their cold-tolerance and had low, summer levels of glycerol and low iodine values. In contrast, winter barnacles kept for the same period without food at 5 °C remained cold-tolerant and had high glycerol levels and high iodine values.

The maximum level of free glycerol in the winter corresponded to a concentration in the body tissues of 1 ·06 mM. This is 1000—fold lower than the concentration of glycerol in the pupal haemolymph of glycerol-forming insects and is far below the level necessary to promote general supercooling of the body water. Itis suggested that the mechanism of cold-tolerance in B. balanoides is one oftolerance to freezing, or frost resistance, rather than avoiding ice formation.

Triglycerides and phospholipids are the main lipid components in B. balanoides.

The component fatty-acid patterns of the triglycerides, phospholipids and, in some instances, sterol esters of a number of aquatic molluscs have been determined. The species examined include several of marine origin (Chlamys opercularis, Crepidula fornicata, Mytilus edulis, Neptunea antiqua, Patella vulgata and Pecten maximus) and one of freshwater origin (Anodonta sp.). The marine species contained considerable proportions of highly unsaturated acids of the C and C series (eg. 20:5 and 22:5) which are characteristic of the lipids of most aquatic plants and animals. In general, the relative percentages of 18:1,20:1 and 20:4 (5,8,11,14) were greater in the lipids of the marine gastro-pods than in those of the pelecypods. The differences between the fatty-acid distributions of the Anodonta sp. and marine members of the pelecypoda are analogous to those existing between other freshwater and marine animals. Studies were made of the seasonal variations in the relative proportions and fatty-acid compositions of the triglycerides and phospholipids in P. vulgata. The relative proportions of 20:4 (5,8,11,14) and 20:5 in the triglycerides rose abruptly from minimum values in January to maximum values in March and thereafter declined slowly. These changes were mainly compensated by inverse variations in the proportions of saturated and oleic acids. In contrast to the triglycerides there appears to be no significant seasonal differences in the fatty acid patterns of the phospholipids.

A study has been made of the seasonal variations in the component acids of the lipid fractions of Balanus balanoides. The relative proportions of the polyenoic acids in the triglycerides drop sharply during the winter. They reach a minimum in the early spring and then gradually rise to a maximum in the late autumn. These changes are largely balanced by increases in the saturated acids, principally 16:0 and 18 :o.1 During the winter there is a marked decrease in the triglyceride to phospholipid ratio as the depot fats are mobilised as food reserves. The proportions of the polyethenoid acids in the phospholipids decline slowly during the winter and spring and attain their minimum in June-July. This fall is mainly counterbalanced by increases in the amounts of saturated acids, principally 14:0 and 16:0. It seems likely that the observed decreases in the polyenoic acids are brought about by selective utilization of these compounds as reserves during the winter when food is scarce and depot lipid has been depleted.

The rations removed by adult and stage V Calanus helgolandicus (Claus) feeding on large cells of the diatom Biddulphia sinensis Grev. were measured using an apparatus especially designed to keep the plant cells in suspension and estimated to reach a maximum of 1800 cells/animal/day at a food concentrationof 11,300 cells/1. A continual flow method was used to study feeding at very low algal concentrations and it was found that the animals still captured Biddulphia at a food level of only 270 cells/1.

The animals in the feeding experiments were used at a very low population density (6 copepods/1350 ml.) and the maximum value found for the volume of sea water swept clear – 700 ml./animal/day - was unusually high.

The maximum daily rations consumed by each animal were also high, being equivalent to 47–5 % of the body nitrogen and 46–4 % of the body phosphorus. The number of faecal pellets released by the animals increased with the size of ration captured, but the percentage of the ration lost as faecal pellets was fairly constant. In terms of dietary nitrogen the average value was 65–9% and that for dietary phosphorus 59·6%.

The percentage of the daily ration of nitrogen excreted in soluble form was 266% and that of phosphorus 41–2%, these values being significantly higher than those found using unfed animals. Nearly 90 % of the nitrogen excreted by the animals, whether feeding or unfed, was in the form of ammonia. The amounts of excreted ammonia and total soluble phosphorus increased significantly when the animals fed; but the small quantities of nitrogen released in forms other than ammonia did not change.

P. platycheles was proved to be an osmoconformer, as expected. It is assumed that the other three species are conformers.

Littoral specimens of E. bernhardus have a similar salinity tolerance to P. platycheles, surviving from between 17 and 20·4‰ salinity to between 40·8 and 51‰ salinity if a median lethal time of above 500 h is taken to indicate survival.

The stenohaline species G. squamifera andP. longicornis swell rapidly and die in 60‰ s.w. (20·4‰ salinity). Their locomotion is rapidly impaired by swelling and the integument distorted.

P. platycheles, a moderately euryhaline species, is capable of resisting swelling in 60‰ s.w., and eventually regains its original weight.

Littoral E. bernhardus showed an unusual pattern of volume change in 60‰ xs.w. Initial swelling of 15·4‰ in the first hour was great compared with decapods like C. maenas or P. platycheles, yet did not cause much interference with movement, and was substantially reversed in a few hours.

Increased urine production prevents swelling in P. platycheles. It is thought that increased antennary artery pressure and or a shift to a diuretic hormone balance cause increased nitration by the antennal gland.

Increased urine production is delayed until substantial swelling has occurred in E. bernhardus.

The abdomen of E. bernhardus makes up significantly more of the total animal weight in dilute media than in full sea water, confirming the idea that the abdomen is a ‘swelling reservoir’ protecting the rest of the animal from the mechanical effects of water inflow.

Salt loss in the urine is more important than integumental loss in both E. bernhardus and P. platycheles when they are placed in 60 % s.w.

The luminescent material emitted from the post-cleithral organ of searsid fishes is in the form of granule-packed cells. From this material a partially purified extract may be prepared which shows some of the properties to be expected from a photoprotein. The purified material luminesces on treatment with hydrogen peroxide and, specifically, ferrous iron. The properties of the luminescent system appear similar to those of material isolated from the luminous polychaete Chaetopterus.

The reflecting layers in the external surfaces of salmon were studied during smoltification by making direct observations on the reflecting structures. The relationships between the reflecting layers in the epithelium external to the scales, in the tissues of the scales, and in the skin internal to the scales are given. Some fish, including fish blinded by pseudobranchectomy were reared under very abnormal lighting conditions and the processes of silvering and regeneration of scales followed on them. It was found that the pattern of silvering in smoltification and regeneration was not at all affected by lighting and that, although regenerated scales can easily be distinguished in other ways from those they replace, the orientations and reflectivities of their plate-lets are, with occasional exceptions, almost indistinguishable from those they replace.

An account is given of the effects of changes of concentration of salts in the ambient medium on the colours reflected by the scales of herring and salmon. These lead to the conclusions (1) that in the herring in life the reflecting cells which lie under the scales and outside the scale pocket are in osmotic equilibrium with the external medium and not with the fish's body fluid (2) that the corresponding cells which lie inside the scale pocket of herring are always in equilibrium with these body fluids (3) that in the salmon all parts of the scale, including the parts outside the scale pocket, are in equilibrium with the internal body fluid and osmotically protected from the external medium.

Pressure waves moving across the sand beds at 3 m depth at Le Racou caused circulation of water in the unconsolidated sand layer. The pattern of circulation apparently depended on the depth of the unconsolidated layer and the form of the sand ripples. The rate of flow was determined by the height of the surface waves and the permeability of the deposit. The physical properties of the sands at the crests and in the troughs of the ripples were in part determined by the organic component which in turn would have been governed largely by the patterns and flow rates of the interstitial currents supplying organic material and nutrients to the sand. Differences in the physical properties of the sediment at the crest and in the trough of a ripple due to the organic component were such as would have affected substantially the prevalence of Branchiostoma lanceolatum and harpacticoid copepods. Sand properties dependent on the organic component would clearly be subject to change in accordance with the prevailing weather conditions and hence the supply of organic material. The role of irrigated sands in the removal of organic material from shallow seas is discussed.

Three surveys were made in 1963 and five in 1964 in the area of the English Channel between the English and French coasts and between 3° 40' W and 5°10' W. This area had been surveyed in 1961 and 1962. Temperature and salinity were determined at o, to and 50 m and phosphate silicate and nitrate at 10 and 50 m. The results are presented graphically. Temperature and salinity were compared with Lumby's 25–year averages. The year 1963 started with unusually low temperatures and salinities higher than average. Temperature remained low in the spring, but salinity decreased. The year 1964 started with temperatures and salinities above normal, but during the rest of the year values were close to average. Nitrate in January 1964 was higher than in January 1963. Analyses of suspended matter at 12m were made for carbon, nitrogen and phosphorus on most surveys, and mean values for the whole area are given. Suspended carbon was 67 /ig C/l. in January 1963 and 51 /*g C/l. in January 1964, a significant difference. Increases in sus-pended carbon, nitrogen and phosphorus were found in spring and summer 1964.

Monthly sea temperatures are tabulated for Station E1 from 1960 and for Plymouth Sound from 1958. The 70-year series now available shows that annual means increased by 0·75°C up to the 1950s. Since 1960 inshore temperatures have fallen 0·5°C and E1 surface temperatures 0·4°C. Sea-bottom temperatures at E1 increased 0·4°C between 1920 and the 1950s, and have fallen 0·4°C since 1960. The changes have been most marked in the second half of the year, but the last quarter (October-December) is still somewhat warmer than in 1920 and earlier.

Rich assemblages of acid-resistant microfossils occur in intertidal sediment from the British Isles and are here reported, for the first time, to contain large numbers of dino-flagellate cysts. These cysts provide evidence to show that the distribution of certain dino-flagellate cysts is different from that of the motile stage, that the coastal distribution of cysts appears to be controlled by currents and that their occurrence within bays is possibly related to localized temperature and salinity conditions. Further, they present evidence that potential conditions for a red tide of Gonyaulax polyedra Stein may be present in the east Irish Sea.

The features and history of a poikilohaline lagoon near Titchwell, Norfolk, England, are described and its invertebrate fauna (recorded between 1959 and 1970) is listed. The list includes 44 species new to the lagoon since 1959 (26 species new to the Scolt Head region and four species new to Norfolk). It is considered that the fauna is of the relict type, perhaps representing what remained of a former salt-marsh fauna together with some marine species. Notes are included on the biology and geographical ranges of several species which are rare or have imperfectly known distributions in Britain. The records of five particular species are believed to represent the northern limits of these animals on the east coast in 1971, when Titchwell Lagoon was drained, destroying the fauna and flora.

Methods are described for rearing turbot (Scophthalmus maximus L.) and brill (Scophthalmus rhombus L.) to late larval stages; the major part of the work was done on the former species. Turbot were reared to 16–0 mm and brill to 17–0 mm in length. Rearing tanks ranged in capacity from 8 to 60 1. Turbotlarvae hatched at 2–7–3–0 mm and successful first feeding was established on rotifers (Brachionus plicatilis) at a length of 3–6–3–8 mm; larvae were transferred to a diet of Artemia nauplii at 5–6—6–0 mm. Experiments on the effect of temperature on growth and yolkabsorption rates in yolksac turbot larvae showed optimal growth efficiency at 15–0 °C. Delayed initial feeding reduced subsequent survival. Drawings of larval development of turbot and brill were made as an aid to their identification in plankton samples.

An area in the English Channel of 20 × 40 nautical miles, centred on the Plymouth routine stations L, L and E, was sampled at almost monthly intervals from August 1969 to November 1970, using an improved version of the 1 m net towed at 4 knots on an oblique path. The area includes an inshore region where depths are about 20 fm (37 m) and salinities 35·0‰ or less, and an offshore region with depths over 40 fm (74 m), where salinities can exceed 35·3·. During the first year the offshore region was characterized by water of south-western origin, and temperatures were higher than in the following year when north-western plankton was more in evidence.

The development of Callionymus reticulatus Valenciennes, 1837, from the early postlarval stage (2·7 mm) up to about the end of metamorphosis (11·4 mm) is described. The main differences between its postlarvae and the postlarvae of C. lyra Linnaeus, 1758 and C. maculatus Rafinesque-Schmaltz, 1810 are described and illustrated. The spawning periods of the three Callionymus species are briefly discussed and the seasonal occurrence and distribution of their postlarvae off Plymouth are given.

The breeding cycle and growth of a population of Littorina littorea (L.)from an exposed rocky shore is compared with a population from a neighbouring sheltered estuarine habitat. The estuarine population matures earlier in the year, and maximum spawning activity is recorded in January compared with March on the open coast. This is considered to be the result of the higher nutritional status of the estuary. Egg capsules and veliger larvae have been found amongst the detritus on the estuary, and the establishment of an earlier settlement in this population is explained by concluding that a substantial proportion of the egg capsules do not leave the estuary, but undergo their full development in the moist detritus. At both localities individuals are sexually mature at a shell height of about 11–12 mm. Snails from the estuary reproduce for the first time during their second winter compared with the second or third winter for the open coast population.

The vertical distributions and diurnal migrations are analysed for nineteen species of calanoid copepods in the families Lucicutiidae up to and including the Candaciidae. The relative abundance, both vertical and horizontal, is given for each species.

With few exceptions most of these species show little or no vertical migration. There is some suggestion of a reversed (downward) migration for Paracandacia bispinosa andP. simplex but since there are difficulties in analysing the surface samples the evidence is inconclusive. The species which are abundant in the family Heterorhabdidae all have little or no vertical migration and are at least partially vertically segregated by both day and night. Phyllopus impar and P. helgae are clearly vertically segregated and Haloptilus acutifrons and, to a lesser extent, H. ornatus each have two vertically separated populations by both day and night. Two size groups are present in each sex of Lucicutia flavicornis.

The vertical distributions and numbers throughout the water column are analysed for 203 and 176 species in the day and night series respectively; it is concluded that while many species are relatively abundant at one or more particular depth most of them are numerically relatively insignificant in the water column as a whole. Only two species (day) and four species (night) formed more than 5 % of the total numbers caught in their respective series.

The relative abundance, both vertical and horizontal, of the commonest genera are analysed. In the whole water column the relative abundance of most of the genera is constant by both day and night, and, as with the individual species, most of them are relatively scarce.

A new method is proposed for the determination of total dissolved free fatty acids (FFA) in sea water. After preliminary extraction by chloroform, a copper complex is formed which is then extracted by a chloroform-heptane solution. Copper concentration is measured by atomic absorption spectrophotometry. The method is particularly adapted to the determination of long chain FFA (longer than C10) and dissolved organic matter usually present in sea water gives no interference. At the 30 μ/l. level the standard deviation is 1 μ/l. for seven determinations.