The importance of the extensive intertidal mud-flats to the energy budget of estuaries has frequently been stressed, but seldom quantified. Smidt (1951) has discussed the production of both macro- and meiofauna from the Danish Waddens in general terms but, because of the wide coverage, his information is not detailed enough to quantify annual production in terms of g/m2. The present study was designed to compare the productive importance of macrofauna and meiofauna in detail at a single site. This paper deals only with the first phase of this study, the macrofauna, which are retained on a 0.5 mm sieve for the major part of their productive life.

The mining of china clay in Cornwall is an industry dating from the middle of the eighteenth century, and one which has grown to major prominence in the south-western peninsula, as illustrated by the historical accounts of Barton (1966) and Hudson (1969).

Present-day mining processes give rise to two main types of particulate waste. The coarser waste, or tip-sand, is deposited on land to form the massive white tips which characterize the scenery of the Cornish china clay mining areas, although small amounts may be used locally as a building aggregate. The finer-grained waste, known as micaceous residue, is produced in lesser quantities and is disposed of in a different manner.

The family Rissoidae comprises 24 British species, occurring, many in great profusion, in both littoral and sublittoral marine habitats. On rocky shores the most prolific species is Rissoa parva (da Costa), which occupies a number of microhabitats, algae in particular, centred on the infralittoral fringe but reaching as high as M.T.L., and may also be found sublittorally off these shores.

Breeding and development have been studied in a number of sipunculans, including Golfingia elongata (Keferstein), G. vulgaris (de Blainville), G. minuta (Keferstein), G. pugettensis Fisher, Phascolosoma agassizi Keferstein, Phascolopsis gouldi (Pourtalès), Themiste pyroides (Chamberlin), Phascolion strombi (Montagu) and Sipunculus nudus L. (see Åkesson, 1958, 1961; Gerould, 1903, 1904, 1906; Hatschek, 1884; Rice, 1967; Selenka, 1875). However, the annual cycle of gametogenesis has been investigated in very few sipunculans, notably G. vulgaris (Gonse, 1956 a, b, 1957a, b) and P. agassizi (Towle & Giese, 1966, 1967).

In a short paper presented to the 12th International Congress of Zoology in Lisbon in 1935, L. Fage described a new species of polychaete, Lumbriconereis flabellicola, living on a coral of the genus Flabellum in 450–600 m off Morocco (Fage, 1936) (PI. VIII, c). The dissolution of the calcareous coral skeleton to form a groove beneath the tube of the worm was well described and figured by Fage, who noted a report of a similar scleractinianpolychaete association from 489 m, off Spanish Sahara by Marenzeller (1904). Subsequently, palaeontologists have shown interest in the association described by Fage, but it has remained largely unknown to biologists, though mentioned in check lists (Hartman, 1951, 1959; Amoureux, 1973b) and in Grasse's Traite de Zoologie (Fauvel, 1959). The generic name Lumbrineris Blainville, 1828, has priority over Lumbriconereis Grube, 1840, and is now in general use.

In a recent paper, Green & Parke (1974) drew attention to some of the systematic problems posed by benthic members of the Haptophyceae. Particular attention was given to Ruttnera spectabilis Geitler (1942) the type species of its genus, which was shown by the fine structure of the zoids to be a member of the Haptophyceae with a characteristic rudimentary haptonema and not, as had been thought previously, a member of the Chrysophyceae (sensu Christensen, 1962). Attention was also drawn to the close similarities between R. spectabilis and Chrysotila lamellosa Anand (1937) both in the vegetative and motile phases, but no formal taxonomic changes were made pending the completion of the comparative reinvestigation of both these species together with C. stipitata Anand, the type species of the genus Chrysotila (so designated by Bourrelly, 1957).

‘Giant’ nerve cells have always attracted considerable interest because of the technical possibilities they offer to experimental biologists, for as well as being easy to impale with microelectrodes they can be dissected away from non-nervous tissues and used for bio-chemical analyses.

The general biology of the gadoid fishes of the North Sea after recruitment to the demersal fisheries has received considerable attention, but little is known about their behaviour patterns during the period between metamorphosis and assumption of the demersal habit. In the summer of 1969 the Marine Laboratory, Aberdeen, began a series of annual midwater trawling surveys of the northern North Sea (Hislop, 1970, 1972a, b; Hislop & Bailey, 1971, 1975). During the surveys observations were also made on various aspects of the biology of the species caught. This paper describes the results of a series of trawling experiments carried out on a cruise of F.R.S. ‘Scarba’ (ex ‘Scotia’) between 12 and 29 August 1971.

Little work on vertical distribution of cephalopods was possible before the development, in the 1960s, of sophisticated opening-closing devices usable on midwater trawls such as the 10 ft Isaacs Kidd trawl (IKMT; Foxton, 1963; Aron et al. 1964) and the series of rectangular midwater trawls developed by the Institute of Oceanographic Sciences (previously the National Institute of Oceanography) (Clarke, 1969 a; Baker et al. 1973). These developments have resulted in three papers on vertical distribution of cephalopods in the North Atlantic (Clarke, 1969 ft; Gibbs & Roper, 1970; Clarke & Lu, 1974) and one for the Mediterranean (Roper, 1972). The present paper describes the vertical distribution of cephalopods caught at 40° N 20° W, 53° N 20° W and 60° N 20° W in the North Atlantic based upon day and night series of horizontal hauls between the surface and 2000 m using the RMT combination net (Baker et al. 1973).

The present work is part of an analysis of catches made with rectangular midwater trawls (RMTs) in the North Atlantic at about 20°W and at 60°N, 53°N, 40°N (all in Lu & Clarke, 1975), 30°N (Clarke & Lu, 1974), 18°N and 11°N (Lu & Clarke, 1975). The collections were made for the ecological programme of the National Institute of Oceanography, Wormley, England (now part of the Institute of Oceanographic Sciences).

Crisp & Meadows (1962, 1963) have shown that aqueous extracts of whole barnacles, when applied to an inert test surface renders the surface attractive to barnacle cyprids thus simulating the gregarious response displayed at settlement. The factor responsible for promoting the settlement of cyprids of Balanus balanoides has been shown to be nondialysable, resistant to boiling in aqueous solution, and can be fractionated by precipitation with ammonium sulphate (Crisp & Meadows, 1962, 1963; Gabbott & Larman, 1971). In their 1962 paper, Crisp & Meadows showed that the settlement factor was present in untreated extracts of all the arthropod groups they examined (including Carcinus maenas) and in extracts of two species of sponges and the fish Blennius pholis. Extracts of other animals and plants were not active. In particular, untreated extracts of the bivalves Mytilus edulis and Ostrea edulis were inactive when assayed against cyprids of B. balanoides. Recently one of us has shown that boiled extracts, partially purified by precipitation with ammonium sulphate, of whole barnacles (B. balanoides, Elminius modestus and B. hameri), crab carapace (Carcinus maenas), whole heads of the blenny (Blennius pholis) and of the body tissues (excluding the shell) of O. edulis and M. edulis, all contain a characteristic group of acidic proteins, or protein-carbohydrate complexes, with iso-electric points in the range pH 4.0–6.0 (Larman, 1975). This finding has prompted us to re-examine the specificity of the settlement response in barnacles.

Dense aggregations of echinoderms on the sea bed have been described from various parts of the world. Reese (1966) considered that such an aggregation ‘is a response to one or more essential environmental factors such as food or substratum, and does not reflect social behaviour per se’ Observations by Warner (1969, 1971) and by Brun (1969) suggested that, in aggregations of the brittle-star Ophiothrix fragilis, individuals may respond to conspecifics rather than solely to food or the substratum. On an apparently uniform substratum, some areas are covered with a dense bed of brittle-stars while other adjacent areas are devoid of brittle-stars. Warner (1971) pointed out that the aggregations are advantageous to the species so it seems possible that the animals might aggregate actively rather than coming to a suitable feeding area by chance. The aims in this study were to investigate the responses shown by Ophiothrix fragilis to its physical surroundings, to some of the other organisms living near it and, especially, to conspecifics. The animals studied are in dense aggregations off Berry Head in Southern England and all observations were made underwater in the natural habitat.

Basket-stars are suspension-feeders and suspension-feeding by other brittle-stars was suspected long ago on circumstantial grounds, but it is only in the last twenty years that it has been actually demonstrated, and detailed descriptions of suspension-feeding behaviour are still available for only a handful of species. Blegvad (1914) pointed out that Ophiothrix fragilis (Abildgaard) and other species lead sedentary lives and feed largely on detritus on, or near, the sea-floor. Wintzell (1918) explicitly suggested tha and Ophiopholis aculeata (L.) are suspension-feeders, primarily on the grounds that they are commonly found in current-swept localities where plankton is rich, in association with known suspension-feeders such as Modiolus, Lima and Alcyonium. The same suggestion was made by Vevers (1952) who noted the occurrence of dense aggregations of O. fragilis in offshore, current-washed areas near Plymouth, and who later observed suspension-feeding behaviour in that species and in Ophiocomina nigra (Abildgaard) (Vevers, 1956). This was only the second time that suspension-feeding had been documented for any (ophiurid) brittle-star, but now it has been described in about a dozen species and suspected in others, mostly members of the Amphiuridae, Ophiactidae, Ophiothricidae and Ophiocomidae (MacGinitie, 1949; Kuznetsov & Sokolova, 1961; Moore, 1962; Magnus, 1964; Buchanan, 1964; Fontaine, 1965; Fricke, 1970; Pentreath, 1970).

Terebella lapidaria L. is a small terebellid common in crevices in the mid-littoral zone of rocky shores in the Plymouth area. The coelom contains abundant coelomocytes charged with haemoglobin in sufficient quantity to give the worm a brick-red colour. T. lapidaria also has a discrete vascular system with haemoglobin dissolved in the plasma. When covered by the tide the worm irrigates its burrow intermittently. When revealed by the tide it cannot do so, and is then left in a thin film of water or in moist air for 3–4 h. We thought it was of some interest therefore to determine the oxygen equilibrium characteristics of these pigments.

The organization, cellular composition and function of the digestive diverticula has been described for a large number of molluscs (Nakazima, 1956; Owen, 1966; Purchon, 1968). Changes in the digestive cells which are associated with intracellular digestion have also been widely recognized (Graham, 1938; Carriker, 1946; J. E. Morton, 1955, 1956, 1959; Owen, 1955, 1966, 1970, 1972; Sumner, 1965, 1966a, b, 1969; Morse, 1968; McQuiston, 1969; Walker, 1970; Merdsey & Farley, 1973). In general the digestive cells show three cyclic phases, (1) absorption, (2) digestion, (3) fragmentation and excretion, and these phases, with only minor modifications, are typical of most molluscs (Owen, 1966). In many groups, especially gastropods, the changes in the digestive cells within the tubules of the digestive diverticula often appear to be synchronized and consequently the tubules have a uniform appearance throughout the diverticula. In the Bivalvia, however, this type of synchrony has not generally been recognized. Since bivalves have been considered to feed more or less continuously (Purchon, 1971; Winter, 1973) it is not surprising that a homogenous appearance was only exceptionally observed, e.g. J. E. Morton (1956), J. E. Morton, Boney & Corner (1957).

The growth of littoral and sublittoral barnacles has been studied in some detail using linear, surface or volumetric measurements (see Barnes & Barnes, 1959). The growth curve in terms of linear dimension generally included an extended straight section which implies, assuming a constant shape, that the volume is increasing with time in proportion to the area (Crisp, 1960). Hence a plot of basal diameter against time is the simplest characteristic of the growth during most of the life of an isolated specimen. In most studies the shells are measured at daily, weekly or monthly intervals and the effect of different factors on growth evaluated. Thus, it has been claimed experimentally that many factors influence directly the growth of barnacles. These factors and their effects are outlined in Table 1.