Nutrient-limited batch cultures of two marine phytoplankton have been subjected to aeration and varying rates of mechanical agitation and the effects of growth and uptake of 14C and nutrients recorded. In both phosphate- and nitrate-limited cultures the lag period decreased with increasing agitation rate. Cell division times in the exponential phase decreased with increasing agitation of phosphate-limited cultures but increased in comparable nitrate-limited cultures. Division times were increased in all aerated cultures. The final yield of phosphorus-limited cultures was greatest at the highest agitation.

Three species of Photis Krayer are recorded from British and Irish waters. P. pollex Walker is re-established as a distinct species, synonymous with P. macrocoxa Shoemaker which becomes a junior synonym. A key to the British and Irish species is given, together with figures and descriptions of P. pollex and P. reinhardi. P. tenuicornis which is doubtfully recorded from these waters is also figured.

The Iceland scallop (Chlamys islandica) (O. F. Müller) has its main distribution within the subarctic transitional zone where it is found on gravel or sandy bottoms at depths ranging from 10–100 m and usually in places with strong currents (Ekman, 1953; Wiborg, 1962).

An account is given of the variations of shape, colour and patterns of surface sculpture of the shells of ovoviviparous, upper-shore periwinkles of the Littorina ‘saxatilis’ speciescomplex from the sea-coasts and estuaries of south-west England. Variations of shell shape derive from the differing geometries of the helically coiled shell cone. The rate of expansion of the cone is constant in each individual shell, but varies in the component shells of a population and (more widely) between one population and another. The area of the shell aperture is a measure of the expansion rate. Samples of ‘saxatilis’ were taken from some 65 localities covering a wide range of shore environments and, whenever possible, at closely comparable tidal levels (the Pelvetia (P) belt/approx. to M.H.W.S.) and aperture measurements made of shells of all lengths from 1–10 mm (age ca. 0·1–2 years). The apertures of pre-emergent shells teased from the brood pouches of mature females, and of ca. 0·4–0·6 mm length, were also measured. Population aperture-size comparisons were founded primarily on subsamples of shells 10 ± 0.5 mm long - the P-10 aperture-size statistic; and the possible adaptive value of aperture (and foot) size variations were sought through matching relationships with varying conditions of wave attack, shore gradient, platform structure and other features, of which assessments were made in the field. Logarithmic plots of the sequences of aperture-size/shell-length measurements of pre-emergent and post-emergent shells show that the cone geometries are genetically determined, and there is some evidence of the adaptive selection of some geometries and ranges of aperture size in preference to others, mostly in the early post-emergent stages of growth

Parathemisto gaudichaudi was collected off the south coast of Northumberland during 1970–2, and the moulting and growth of laboratory-maintained individuals observed. The moulting behaviour is similar to that described for other amphipods, but individuals remain attached to medusae during moulting. The minimum body size at maturity, the time from hatching to maturity and the length of the intermoult period are shown to be temperature dependent. The analysis of growth-factor data resolves growth into a rapid juvenile phase and a slower adult phase. The development of secondary sex characters is related to developmental stages of the gonads.

Seasonal changes in the rate of shell formation frequently affect the surface morphology of molluscan shells, with reductions in feeding activity and calcification rates at low temperatures producing winter rings that can be used for age determination. Such annuli are well-known in lamellibranchs and have greatly facilitated studies on their growth, longevity and other age-related processes (as reviewed by Wibur & Owen, 1964; Rhoads & Panella, 1970; Comfort, 1957, 1979). However, they occur less frequently in gastropods and many species that do show such checks are relatively short-lived, or else their growth ceases or becomes erratic on sexual maturity.

An experiment was performed to assess the productivity, food chain efficiency and nitrogen conversion efficiency of a semi-closed nursery system for bivalve spat held in upwelling columns. Algal blooms were encouraged by nutrient enrichment of onshore tanks and maintained for short periods under grazing pressure from bivalves.

A model has been used to assess the relative importance of the various factors contributing to changes in the salinity of the eastern English Channel between 1948 and 1973. As part of the data input to the model, monthly means (1948–73) of total runoff into the eastern English Channel and monthly estimates of evaporation and precipitation for the same area (1961–73) were calculated. The results of this study have shown that river runoff is an important factor contributing to the variability of salinity in the eastern English Channel; rainfall over and evaporation from the Channel may also be important at certain times. The model can predict satisfactorily more than 80% of the variation of salinity from local data inputs. While Atlantic water movements and salinities may contribute to variability at the entrance to the English Channel, variations of flow through the Channel, caused by local wind forcing or originating further out in the Atlantic, have little effect on the fluctuations of salinity in the eastern English Channel. Furthermore, fluctuations in the salinity of the North Atlantic do not correspond to those observed at the entrance to the English Channel. River runoff and mixing due to the wind and tides appear to be the main factors responsible for the seasonal changes of salinity in the eastern English Channel.

Globigerinoides sacculifer (Brady), a common planktonic foraminifer collected by SCUBA off Barbados, was maintained under six feeding regimes at constant light and temperature conditions. Five groups of 63 specimens each were fed 1-day-old Anemia at the rate of one nauplius per specimen every 1, 2, 3, 4 or 7 days. A starved control group received no Anemia. The rate of chamber formation and shell size increased proportional to the feeding frequency. However, an inverse correlation existed between survival time and feeding frequency. Normally, survival time ends with gametogenesis which terminates the life of the mother cell. Organisms fed more frequently reached maturity and underwent gametogenesis more rapidly than those fed less frequently. The average survival time of G. sacculifer in culture ranged from 7 days for the daily-fed group to 11 days for the group fed every 7 days. While the latter grew more slowly they eventually reached maturity. Starved individuals rarely formed chambers and often died without undergoing gametogenesis. Symbiotic zooxanthellae presumably prolonged survival of starved organisms. Extrapolation of survival data suggests G. sacculifer has a variable life span of 2 to 4 weeks depending on food availability.

Macrobenthic infauna was sampled in Mevagissey Bay, off the south coast of Cornwall, England, when the bay was receiving fine-grained mineral waste from the china clay industry at a rate of about 450000 tons per annum. Quintuplicate 0·1 m2 grab samples, washed on a 0·5 mm mesh, were taken on 15 occasions over two years at a station about 1 km from the outfall and at a water depth of 13 m. The fauna had a range of density of 755–2144 individuals/0–5 m2 and in composition resembled a partially impoverished Echinocardium cordatum/Amphiurafiliformis community. Population densities of Goniada maculata (Polychaeta), Cingula semicostata (Gastropoda), Nucula turgida, Mysella bidentata, Venus striatula and Tellina fabula (Bivalvia) showed no clear trends during the two years' sampling. Magelona filiformis (Polychaeta), Abra alba and Phaxas pellucidus (Bivalvia), Acrocnida brachiata and Amphiura filiformis (Ophiuroidea) declined in abundance, whereas the densities of Nephtys hombergi (Polychaeta) and Labidoplax digitata (Holothurioidea) increased. L. digitata became the commonest species, with a peak density of 708 individuals/0·5 m2. A month after sampling began the rate of waste discharged was reduced from 700000 tons per annum, but this did not appear to improve conditions for the benthic community. Total faunal density remained relatively stable but species diversity declined. It is argued that the suspended solid concentration was unlikely to have adversely affected the predominantly deposit-feeding community, but that persistent sediment instability continued to be a source of stress. Nevertheless, the observed major changes of community structure were similar to natural fluctuations of coastal soft-bottom populations resulting from species interactions and differences of larval success.

Skeletal form is the key to silicoflagellate taxonomy. Variations in skeleton morphology have been frequently described for the genera Dictyocha and Distephanus (Lemmerman, 1908; Deflandre, 1932; Hovasse, 1932; Frenguelli, 1935; Boney, 1973, 1976), and the wide ranging skeletal variations observed with clonal cultures of Dictyocha fibula Ehrenb. underline the potential plasticity of skeleton formation in this species, (Van Valkenberg & Norris, 1970). Sufficient information now appears available to indicate where taxonomic confusions may arise, particularly when single skeletons are observed either in phytoplankton samples or in fossil deposits. Paired skeletons are predivision stages (Gemeinhardt, 1930; Hovasse, 1932; Marshall, 1934; Boney, 1976). The juxtaposition of the two skeletons in this predivision stage allows a more critical assessment of the taxonomic significance of an aberrant form.

The lipids of four marine coccolithophorids (class Haptophyceae), Emiliania huxleyi, Hymenomonas carterae, Isochrysis galbana and Crystallolithus hyalinus, were examined by capillary gas chromatography-mass spectrometry. Fatty acids ranged from C14 to C22 and were predominantly of even chain length. The major acids were polyunsaturated C18 acids, 22:6 and either 14:0 or 16:0. C20 fatty acids were of low abundance. Significant amounts of octadecapentaenoic acid (18:5), previously thought to be unique to dinoflagellates, were identified in three of the algae. A small amount of a di-unsaturated C36 w-alkenoic acid was identified in E. huxleyi, which is the first report of such a long-chain fatty acid in any alga. Traces of wax esters, which are reportedly uncommon inalgae, were found in three of the species. The sterol distributions were very simple, with two or three compounds accounting for > 99% of the total sterols. In each case, the major component was 24-methylcholesta-5,22E-dien-3β-ol. H. carterae and C. hyalinus also contained 24-ethylcholesta-5,22E-dien-3β-ol and significant amounts of cholest-5-en-3β-ol were found in E. huxleyi and I. galbana. An unusual sterol, 23,24-dimethylcholesta-5,22E-dien-3β-ol, was identified in H. carterae. These sterols were mostly non-esterified although small amounts of sterol esters were identified in E. huxleyi. The lipid composition of E. huxleyi is distinctive in that it contains, in addition to the C36 fatty acid, novel C37–C39 unsaturated ketones and C31–C38 alkenes. Of the other coccolithophorids only I. galbana contained small quantities of one of the C3l alkenes.

In the course of benthic surveys carried out around the U.K. by the Oil Pollution Research Unit, a number of species of polychaete not previously recorded from British waters were found. A new species of Aricidea and six other species of the Paraonidae new for Britain have been described by Hartley (1981), and this note records a further five species taken either in the Firth of Forth (56° 19′ N, 3° 34.8′ W, 2–5–5 m depth, fine sand) or in the Forties oilfield (57° 44.0′ N, o° 54°0′ E, 100–130 m depth, fine to muddy sand) with 0.1 m2 Van Veen/Day grabs in September 1979 and June 1978 respectively. The sieve mesh used was 0.1 mm diameter.

The paired excretory organs or maxillary glands of the adult barnacles, Balanus balanoides and Balanus hameri, lie within the posterior part of the body below and to either side of the foregut. Each organ has an end sac linked to an efferent duct via a valve. The sac-shaped efferent duct connects with a relatively short terminal duct, opening out at the base of the second maxilla. The end sac consists of podocytelike cells having marked morphological and cytochemical similarities to the equivalent region of other Crustacea and to the vertebrate glomerulus. The main cells of the valve contain extensive apical secretion. They rest upon a series of modified end-sac cells projecting into the efferent duct. The efferent duct is composed of a uniform flattened epithelium which is cytochemically unreactive. The cells are lined by a short microvillous border, below which is a series of tubules which appear to be invaginations of the apical membrane. The morphology of efferent duct cells is not indicative of a highly active solute reabsorptive epithelium, but secretion of membrane-bound bodies into the efferent duct lumen was observed. The terminal duct is a relatively short, cuticle-lined ectodermal infolding. The parenchyma cells surrounding the efferent duct exhibit a marked affinity for certain dyes when injected into the haemolymph, indicative of a possible role in the elimination of material. The excretory organ is surrounded by a network of elastic fibres and is suspended within the body by strands of connective tissue and a complex series of tendon-muscle connexions. The end sac is well supplied with haemolymph from the scutal sinus but the supply to the efferent duct is more restricted.

Details of the gross cellular changes taking place in the gonadial tissues and coelom of Ficopomatus during the annual reproductive cycle are presented. There is no true gonad in either sex; instead, germ cell precursors are produced by divisions of a germinal epithelium associated with the ring blood vessels in the intersegmental septa.

Segments producing gametes do not all develop simultaneously; the posterior segments are generally at a more advanced stage of sexual maturity. The later stages in gamete development take place free in the coelom, where nourishment is supplied presumably by the mobilization of materials formerly stored in tissues surrounding the gut.

Spawning commences in June and continues through to October, with peak activity coinciding with the period of high water temperature in August and early September. The adult population comprises males, females, and protandrous hermaphrodites which in the male phase become sexually mature in advance of the rest of the population, and as females later on. These transitional individuals are thought to contribute a negligible amount to the effective reproductive output in those populations living where there is marked temporal constraint on the period of reproduction.

The different reproductive capacities of temperate and tropical Ficopomatus are considered.

In conjunction with a tagging experiment on Callista chione (L.) in 1976, a small number of the large bivalve Arctica islandica (L.) (Family Arcticidae) were also tagged in a similar manner with plastic discs cemented on to the shell with fast-setting cyanoacrylate adhesive. Arctica is less common in Whitsand Bay than Callista but extends into deeper water, 50–60m. Holme (1953) suggested that the species is long-lived and produced spat infrequently. A few young Arctica have been taken in Whitsand Bay (length 29–37 mm) and also, more commonly, specimens of 80–100 mm. In 1976 five Arctica were tagged and relaid, three of these were recovered in 1977 and one in 1978. Three more were tagged in 1978 and searched for without success in 1979. The recovered specimens did not appear to have moved at all. The results of shell length measurements, though meagre, indicated that growth was very slow. For a shell of 82 mm length the increase was 1–5 mm in a year. For a shell of 101 mm there was no increment after two years. For a shell of 102 mm the annual increment was probably 0-1 mm. In this instance it seems likely that the original length should have been 102–3 mm instead of 103–2 which was recorded. For a shell of 108 mm an increment of 0–3 mm was found after 12 months. From these results the average increment of shells over 100 mm length is likely to be of the order of 0-1 mm per year.