Quantitative studies of the meiofauna of marine littoral sediments have been attempted only recently. Much of the work has been done in sheltered areas such as the Danish waddens (Muus, 1967), and in estuaries (Barnett, 1968; Capstick, 1959; Rees, 1940; Riemann, 1966), or in tideless areas such as the Baltic (Fenchel & Jansson, 1966; Fenchel, Jansson & von Thun, 1967; Jansson, 1968). Beaches exposed to tides and wave action have received less attention. Renaud-Debyser (1963) studied quantitative temporal variations in the meiofauna of beaches at the Bassin d'Arcachon, France, and Island of Bimini, Bahamas. Renaud-Debyser & Salvat (1963) have compared quantitatively the meio- and macrofauna of four beaches in the English Channel and six on the Atlantic coast of France. Schmidt (1968, 1969) has analysed quantitatively the distribution and population dynamics of the meiofauna of a number of beaches on the Island of Sylt off the German North Sea coast. Recently Mclntyre (1969) has reviewed the ecology of the meiobenthos. Subsequent to Mclntyre's review, in the U.S.A. quantitative investigations of the Gastrotricha (Hummon, unpublished) and Tardigrada (Pollock, 1970) of Massachusetts beaches have been made. Tropical beach meiofauna has been studied in India (Mclntyre, 1968), on the east coast of Malaya (Renaud-Mornant & Serene, 1967) and in Tuamotu, Polynesia (Salvat & Renaud-Mornant, 1969).

During the last 3 years a survey of marine lipids has been in progress in this laboratory. Several classes of marine animals have been analysed for their fatty-acid composition. These results have shown a considerable species variation but no estimate could be made of the effect of season and environment. It was therefore decided to choose an inshore animal, which could be readily collected, and to examine its lipid composition with regard to seasonal and environmental changes.

The brackish-water, partly planktonic mysid, Neomysis integer (Leach), was selected. This species has already been the subject of much biochemical study (Raymont, Austin & Linford, 1964, 1966, 1968; Linford, 1965), in which the three major fractions protein, lipid and carbohydrate were examined. The lipid weight was found to be low in comparison with the protein content. Also, significant decreases in the lipid were found in November, January and March. It was concluded that N. integer stored little lipid as a metabolic energy reserve, and as the carbohydrate was low, protein may be catabolized. Only one sample analysis for fatty-acid composition was reported.

The marine species Neomysis nakazaviai has been investigated by Yamada (1961), but unfortunately an ether extract was taken from sun-dried material and so the results are not comparable with the present work on Neomysis integer.

In the present study the saponifiable fraction of the lipid is examined in more detail in an attempt to establish the relative importance of the factors of season, temperature and salinity upon the fatty-acid composition.

During recent cruises of R.R.S. ‘Discovery’ in the eastern North Atlantic an investigation has been made of the depth distribution and diurnal migration of the pelagic fauna in selected oceanic areas. This continuing programme has entailed intensive mid-water sampling with opening-closing nets, fishing discrete depth horizons mainly within the upper 1000 m but also on occasion at greater depths. Hauls made during the cruise of January-April 1968 in a position 11°N, 20°W, south-east of the Cape Verde Islands, yielded 43 specimens of an apparently new species of the genus Acanthephyra. A further 113 specimens were taken during a subsequent cruise to the same area and the species has also been recorded in a sample collected in the Indian Ocean during the International Indian Ocean Expedition.

Having examined the literature and concluded that the species was undescribed the author referred to the large collection of decapod Crustacea that had been amassed as a result of cruises of ships of the Discovery Committee made prior to 1939. This material, together with that taken on the Dana Expeditions, had formed the subject of Dr Stanley W. Kemp's extensive studies on the Oplophoridae (Kemp, 1939), consequently the carefully preserved, labelled, and identified specimens represent a unique reference collection. It proved to contain five specimens identical to those taken at 11°N in 1968. Not unexpectedly Kemp had realized their uniqueness and had not only designated the type but named it. A description, however, was never published although it was prepared and has in part survived.

When beginning research into the cultivation of marine shrimps and prawns, it is usually the most worth while of the local species that is chosen for study. From this it follows that in tropical regions the penaeids tend to be favoured, especially following the pioneering work of Hudinaga (1942) with Penaeus japonicus (Bate), whereas in the temperate regions of Europe and Canada it is the carideans that are receiving most attention, particularly the palaemonids. One notable exception is the advanced study of the Asiatic Giant Prawn Macrobrachium rosenbergii (de Man), which was initiated in Malaysia and subsequently taken up in Hawaii and Great Britain (Ling, 1962).

Doubtless each chosen species has its merits, but overriding importance must be attached to ease of mating, for this imposes an immediate limit on the reliability of the whole process and holds the key to the selective breeding of improved strains. Indeed, it has been pointed out that reliance on wild-spawned animals is a major obstacle to commercial development (Tabb et al., 1969) and such vagaries in the supply of young shrimps has already limited some research (Cook & Murphy, 1969).

Under captive conditions it has proved a great deal easier to mate carideans than penaeids, but the continuing part played by caridean females in incubating the eggs over a contracted period is a disadvantage. Relieving the ovigerous females of this task would allow the eggs to be incubated at greatly increased densities in conditions no longer dictated by the females. Further, it would lead to the more effective use of the female during the period she would otherwise be incubating.

Growth of shells of larvae of Nassarius reticulatus (L.) and Crepidula fornicata (L.) reared in the laboratory under constant temperature (14 °C) and illumination (155 lx) occurs by the addition of successive strips secreted at the mantle edge. Growth lines on the embryonic teloconch also indicate intermittent growth; the protoconch secreted by the shell gland has no such lines. There is evidence that growth periods are short and pauses separating them prolonged. The diameter of the older whorls of the shells of these and six other species examined increase with the volume of the viscera. This change in diameter is made possible by the flexibility of the organic matrix, the funda-mental constituent of the shell. The matrix, secreted as fibres at the mantle edge, forms sheets, and provides sites for the deposition of calcareous concretions; at metamorphosis the concretions apparently initiate the formation of crystals. The concretions also sculpture the surface of the shell producing a pattern sufficiently conspicuous to allow identification of some species with the aid of only the stereomicroscope. For example, large concretions form longitudinal rows over the protoconch and teloconch of Littorina neritoides (L.) and smaller ones combine to form a more decorative pattern in Rissoa sarsi Loven. In other species details of the surface design require a scanning electron micro-scope. Interspecific differences in the arrangement of concretions may be traceable to differences in the pallial glands which secrete the matrix.

INTRODUCTION

In common with other plants, marine phytoplankton will only thrive if they are able to obtain essential trace elements. There is some evidence that shortages of available iron and manganese may occasionally restrict the growth of these organisms (Harvey, 1939, 1947). However, other essential trace metals are present in the sea at concentrations which, although very low, appear to be adequate to sustain abundant growth. The concentrations of trace elements necessary for optimum growth differ considerably from species to species (see e.g. Harvey, 1947; Goldberg, 1952). Krauss & Porter (1954) have demonstrated that manganese, iron and zinc are taken up by the freshwater alga Chlorella pyrenoidosa in proportion to their concentrations in the medium. However, this is not true for all elements, at least so far as the larger algae are concerned (Young & Langille, 1958). The concentrations of trace elements present in phytoplankton grown in culture may also depend on the age and density of the culture. Thus, Hayward (1969) has shown that although iron and zinc were initially rapidly taken up by Phaeodactylum tricornutum from a medium rich in chelated forms of these metals, their concentrations in the cells decreased as their numbers increased. The uptake of trace elements is not confined to those which have a definitely established physiological function.

INTRODUCTION

The results of bottom line fishing have shown that significant catches can be made down to 3000 m depth at several positions on the continental slope off south-west England (Forster, 1968). But when hooks were lifted off the bottom either deliberately or accidentally very few fish were taken. The chances of catching bathypelagic fish in mid-water by baited hooks therefore seemed slender. In 1966 when thin white lines were tried, they were bitten through several times, always at about 1100 m depth. Trials with baited hooks set on thin wire lines in 1967 showed that the black scabbard fish Aphanopus carbo could be taken at this depth. In 1968 and 1970 during the course of short voyages on R.V. ‘Sarsia’ further vertical line hauls were made, taking Aphanopus regularly and also two species of deep-water squaloids.

INTRODUCTION

The retinae of deep sea fishes have been studied by optical microscopy by several authors. Brauer's (1908) work is the most important early account, and the major recent work is that of Munk (1966a). In this monograph he reviews previous papers including that of Contino (1939), Franz (1907), Hanyu & Ali (1962), Verrier (1931), Vilter (1953, 1954a, b) and Wunder (1958), and also describes the eyes of a number of species himself. Since then Munk (1966b and 1968) has described other species by optical microscopy. Locket (1969, 1970) has used electron microscopic methods of fixation to study two species by optical and electron microscopy. These two fishes, Poromitra nigrofulvus and Sternoptyx diaphana, are not closely related and have different retinal structures. Poromitra has banks of rods in its retina, a condition first described by Vilter (1953) in Bathylagus; Sternoptyx has a single layer of long rods, a condition also found in the present species. The earlier authors worked on material collected during research expeditions and preserved in alcohol or formalin. During the 1966 biological cruise of R.R.S. ‘Discovery’ Locket was able to fix eyes from deep-sea fish with a view to electron microscopy. Though the fixation is not perfect, it does preserve much ultrastructural detail and interspecies variation in retinal structure can be studied in this material.

INTRODUCTION

Until recently only two marine members of the phylum Tardigrada were known to occur in Britain. Echiniscoides sigismundi (Schultze), was found associated with mussels (Green, 1950) and intertidal barnacles (Crisp & Hobart, 1954). The interstitial species, Batillipes mirus Richters, was located at beaches in North Wales (Boaden, 1963) and Strangford Lough in Northern Ireland (Boaden, 1966).

Interstitial tardigrades have been reported from several localities around the North Sea. The fauna of the German coast is particularly well studied; Schultze, 1867; Richters, 1908, 1909; Schulz, 1935, 1951, 1953; Grell, 1937; Remane, 1940; Freidrich, 1963; Riemann, 1966a, b; Schmidt, 1969. This German fauna includes three species of Batillipes and single representatives of five other genera. In addition, E. sigismundi and B. mirus have been found in Norway (Tambs-Lyche, 1939–40). Along the French coast of the English Channel, eight species from six genera are reported. While most studies originated at RoscofT, including Cuénot, 1892; Cantacuzène, 1951; Guèrin, 1960; Swedmark, 1951, 1955, 1956a; Swedmark & Teissier, 1967; Thulin, 1942, two species of Batillipes have been located elsewhere on the northern coast of France (Renaud-Debyser & Salvat, 1963).

In recent surveys of beaches in Britain, additional tardigrades have been located. Gray & Rieger (1971) reported their occurrence at several beaches on the north-east coast of Yorkshire, especially at Stoupe Beck, Robin Hood's Bay and Filey Beach near Scar-borough. Also, A. D. Mclntyre has found them in his collections at Firemore Bay in Loch Ewe on the west coast of Scotland. This paper describes specimens generously provided from these two studies.

INTRODUCTION

The atomic ratio of oxygen-consumed to ammonia-nitrogen excreted by marine organisms (O:N ratio) is more conveniently and precisely determined with current analytical procedures than the respiratory quotient (R.Q.). When an organism is oxidizing protein exclusively the O: N ratio will be low, less than 7; it will be high when either fat or carbohydrate is oxidized.

INTRODUCTION

One of the longstanding problems in marine biology has been to determine the quantitative importance of bacteria in the regeneration of the inorganic nutrients. There probably still is no entirely satisfactory way of studying this. It is currently believed that although a variety of marine organisms may utilize soluble organic compounds, bacteria dominate this activity. Thus, a measurement of the amount of soluble organic material oxidized will give a first approximation of bacterial activity. Such an estimate may have to be revised at a later date to allow for the activity of other micro-organisms.

Observations made with the 2 m ring-trawl off Plymouth during the years 1967,1968, 1969 and 1970 indicate that the increased abundance of young fish, excluding clupeids, reported for the year 1966 has been maintained.

For the collections made in 1969 the species of clupeids, Arnoglossus, sand-eels and Callionymus have been separately identified.

The year 1969 was characterized by the high numbers of post-larvae of Phrynorhontbus norvegicus. For the first time on record a post-larva of Sargus sargus was caught. Unusual abundance of post-larvae of the bass, Dicentrarchus labrax, was recorded for May 1970.

INTRODUCTION

It has been known for a long time that the soft tissues of molluscs contain relatively high concentrations of certain trace elements—mainly transition metals (see, for example, Vinogradov, 1953; Bowen, 1966). However, with the exception of the work by Brooks & Rumsby (1965) on the occurrence of 12 elements in 3 New Zealand bivalves, most of the investigations have concerned the distribution of only one or two elements. This has prevented a study being made of possible interelement correlations. The present work was carried out in an endeavour to determine the usual levels of several minor elements in a variety of molluscs from the Irish Sea and to seek evidence for such correlations.

INTRODUCTION

A long-term ecological study is being carried out in the Ythan Estuary in north-eastern Scotland. An understanding of the hydrology of the estuary is a prerequisite for future studies into energy relationships in lower trophic levels of the food web. Much of current research into the estuarine environment is concerned with large coastal-plain systems where physical and chemical characteristics are so different from those of shallow estuaries, such as the Ythan, that comparisons of environmental data are untenable. The present investigation reports information collected between October 1966 and September 1968 on major environmental factors and their effect on the distribution of nutrients and detritus in the ecosystem. Results of a concomitant study of algal productivity in a mudflat of the estuary are reported in Leach (1970).

INTRODUCTION

Studies on the physical hydrography of the Irish Sea, based mainly on temperature and salinity observations, have been made by Bowden (1955) and Lee (1960). The current systems in various parts of the Irish Sea have been investigated by Bowden & Sharaf El Din (1966), Harvey (1968), Ramster & Hill (1969) and Hill & Ramster (1971). Various smaller-scale physical observations made by other workers have been listed by the above authors.

There are not as many references in the literature to the distribution of nutrient salts in the Irish Sea. Jones & Haq (1963) measured phosphate in Liverpool Bay as part of an investigation into the distribution of the alga Phaeocystis. Slinn & Offlow (1968) have made regular routine measurements of phosphate, nitrate and silicate over a number of years off Port Erin, Isle of Man. Ewins & Spencer (1967) measured phosphate, organic phosphorus, nitrate and silicate in the Menai Straits, and Liss (1969) surveyed the distribution of silicate in the western Irish Sea.

During recent years the Fisheries Laboratory at Lowestoft has investigated the distribution and ecology of plankton and larval plaice in the Irish Sea, and a supporting programme of both physical and chemical hydrographic observations has been made in the area. Ramster & Hill (1969) and Hill & Ramster (1971) have summarized the results of the Lowestoft current measurements. The present paper describes an investigation into the distribution of temperature, salinity, phosphate, nitrate and silicate. The occurrence of Phaeocystis is also reported as an extension of the earlier work by Jones & Haq (1963).

INTRODUCTION

Dinoflagellates have often been held responsible for a large part of the phosphorescence of the surface waters of the sea. In temperate waters, dinoflagellates are seldom the most abundant constituents of the phytoplankton, and until recently little experimental evidence has been available to support this assertion. Until recently there have been few careful attempts to determine which particular species of dinoflagellates are luminescent, or to relate total luminescence to numbers of dinoflagellates present.

INTRODUCTION

Initially the haptonema was recorded as a ‘little additional flagellum’ by Scherffel (1899) when he described Phaeocystis globosa. Similarly, the haptonema was referred to as the ‘third flagellum’ on the apparently tri-flagellate, brackish-water Prymnesium saltans Massart (Massart, 1920). Two further brackish water species of Prymnesium were described by Carter (1937) and all were characterized by a very short immobile ‘third appendage’. Lackey (1939) found a freshwater organism similar to Prymnesium but it possessed a ‘third flagellum’ several times the length of the true flagella. He re-corded that the third appendage was held out rigidly when the cell was at rest but during rapid swimming he was unable to see it and thought that this was due to an extremely rapid beat. He named his new organism Chrysochromulina parva and C. parva Lackey is now the type species of a considerable genus.

Parke, Manton & Clarke (1955,1956,1958,1959) made a study of the light microscopy and fine structure of numerous marine species of Chrysochromulina. Their results showed that the ‘third flagellum’ differed in appearance and structure from that of a true flagellum and hence they decided to call this organelle a haptonema owing to its thread-like form and its ability to adhere to a smooth surface (Parke, Manton & Clarke, 1955). Their observations revealed that the haptonema could attach to a surface by an ‘adhesive tip’ and that the majority of species could coil their haptonemata into a helix and extend it again. In some species, e.g. C. strobilus (Parke, Manton & Clarke, 1959), the haptonema was usually tightly coiled whilst the cell was swimming.

INTRODUCTION

The black scabbard fish, Aphanopus carbo Lowe, is an elongate mid-water trichiurid, which is caught commercially off Madeira, and has been recorded, though infrequently, from British waters (Tucker & Palmer, 1949; Tucker, 1956). Twelve specimens were caught during a recent cruise of R.V. ‘Sarsia’ in the Biscay area (Forster, 1970), and this note reports observations on their behaviour, histology and anatomy, which suggest that these fish are highly specialized for a particular method of catching prey.

INTRODUCTION

Recent experiments with symbiosis in the flatworm Convoluta roscqffensis Graff (Provasoli, Yamasu & Manton, 1968; Provasoli, Yamasu & Mabuchi, 1969) reveal an important area in the investigation of algal-invertebrate associations, demonstrating the potential of studies based on the principle of cross-infections using various experimental symbionts. The studies which these authors describe are feasible only if detailed taxonomic data are available to facilitate rapid identification of symbionts in situ. This kind of experimentation is impossible in symbiotic systems involving ‘zooxanthellae’, because of the general failure to provide adequate descriptions of the genera and species included in this ill-defined group. Admittedly, the situation shows signs of improvement. We now know that the ‘zooxanthella’ associated with C. convoluta Abildgaard is a diatom belonging to the genus Licmophora (Ax & Apelt, 1965; Apelt, 1969), the morphological criteria for the identification of Symbiodinium microadriaticum Freudenthal have been redefined (Taylor, 1969 a) and a revised taxonomic description of this species is now available (Kevin, Hall, McLaughlin & Zahl, 1969). Nevertheless, we are still a long way from achieving a representative collection of well known experimental symbionts for use in comparative studies. It therefore seems worthwhile (not merely an exercise in micro-taxonomy and micro-horticulture) to continue to collect, identify and describe the range of genera and species that may be hidden among the ‘zooxanthellae’. The present paper is one in a series (see Taylor, 1969 a, b, c) intended to explore the potential variety of these organisms.