INTRODUCTION

The family Palmariaceae Guiry (Palmariales: Rhodophyta) at present includes the genera Palmaria Stackhouse (the holotype genus: see Guiry, 1974, p. 523), Halosacdon Kiitzing, Leptosarca A. & E. S. Gepp and Neohalosacdocolax I. K. Lee & Kurogi. Halosacdon and Leptosarca were included in the original description of the family (Guiry, 1974) and Neohalosacdocolax was recently described by Lee & Kurogi (1978) for a small parasite on Halosacdon minjaii I. K. Lee from the Aleutian Islands. The structure and reproduction of Neohalosacdocolax make it quite clear that its affinities lie with the Palmariaceae (Lee & Kurogi, 1978). The Palmariaceae of the island of Hokkaido (northern Japan) have been the subject of a recent study (Lee, 1978) and the details of structure and reproduction given for the northwestern Pacific species of Palmaria and Halosacdon confirm that the unusual structure and mode of reproduction described by Guiry (1974, 1975, 1978) for Atlantic and northeastern Pacific representatives of these genera are also found in the northwestern Pacific representatives (see also Lee, 1977a).

INTRODUCTION

In 1976 the Fisheries Laboratory, Lowestoft, carried out 13 plankton sampling cruises off the north-east coast of England. They spanned the months February-November. From these cruises Harding et al. (1978) described the distributions of surface chlorophyll and nutrients and the production offish eggs and larvae. Reynolds (1978) described in more detail the distributions of chlorophyll and phaeopigments throughout the year, and Horwood (1982) detailed the distribution of zooplankton biomass. This study presents the species composition of the algae from a small region of the survey area illustrated in Fig. 1.

INTRODUCTION

Amoebae of the genus Paramoeba Schaudinn, 1896, are among the Gymnamoebia most frequently isolated from marine habitats, and individual species have a wide distribution throughout the world. Unlike many genera of Gymnamoebia, Paramoeba is exclusively marine. The type species, P. eilhardi Schaudinn, 1896, was originally described from a marine aquarium in Berlin with no further information on origin (Schaudinn, 1896); it has been found in the Mediterranean off France (Chatton, 1953; Grell, 1961) and Italy (Grell & Benwitz, 1970) and the Indian Ocean off Madagascar (Grell & Benwitz, 1970). P. schaudinni de Faria, da Cunha & Pinto, 1922, originally described from a sea-water aquarium at Rio de Janeiro, has recently been reported from the Gulf of Mexico (Sawyer, 1980). P. pemaquidensis Page, 1970, has been found on the coasts of Maine, U.S.A. (Page, 1970), Norfolk (Page, 1973), and Essex (Page, unpublished); in open waters off the eastern coast of the U.S.A. (Davis, Caron & Sieburth, 1978); in marine sediments of the western North Atlantic, the Bight of New York, and the Gulf of Mexico (Sawyer, 1980); and in the present study on the shores of North Wales and western Scotland. Paramoeba aestuarina Page, 1970, though not found as often as P. pemaquidensis, is also widely distributed (Page, 1970; Davis et al. 1978; Sawyer, 1980). The first European finding of P. aestuarina is reported in the present paper, but the exact origin of the strain is uncertain. P. perniciosa Sprague, Beckett & Sawyer, 1969, which appears to be an obligate parasite, has thus far been reported only from crustaceans off the eastern coast of the U.S.A. (Sprague, Beckett & Sawyer, 1969; Sawyer, 1976).

INTRODUCTION

Ophiacantha bidentata (Retzius) is a widespread arctic-boreal ophiuroid with a circumpolar distribution in the shallow waters of the Arctic seas and penetrating into the deep sea of the.North Atlantic and North Pacific (Mortensen, 1927, 1933a; D'yakonov, 1954). Early observations of this species were confined to defining zoogeo-graphical and taxonomic criteria including the separation of deep water specimens as the variety fraterna (Farran, 1912; Grieg, 1921; Mortensen, 1933a). Mortensen (1910) and Thorson (1936, pp. 18–26) noted the large eggs (o.8 mm diameter) in specimens from Greenland and Thorson (1936) proposed that this species had ‘big eggs rich in yolk, shed directly into the sea. Much reduced larval stage or direct development’. This evidence is supported by observations of O. bidentata from the White and Barents Seas (Semenova, Mileikovsky & Nesis, 1964; Kaufman, 1974)..

INTRODUCTION

The reproductive biology of asteroids from a wide variety of ecological niches has been examined (Farmanfarmaian et al. 1958; Cognetti & Delavault, i962;Pearse, 1965; Chia, 1968; Crump, 1971; Jangoux & Vloebergh, 1973; Worley, Franz & Hendler, 1977; Barker, 1979; Shick, Taylor & Lamb, 1981). Most of the species within this class appear to show some degree of seasonal reproductive synchrony with very few species showing aseasonal reproduction (Shick et al. 1981). Although the seasonally reproducing asteroids show a wide variety of reproductive strategies, from planktotrophic larvae to direct development, they all occur in relatively shallow water and are thus subject to the seasonal fluctuations of the physico-chemical environment. Only two shallow-water species, Ctenodiscus crispatus (Shick et al. 1981) and Patiriella exigua (Lawson-Kerr & Anderson, 1978), have aseasonal reproduction in both males and females. However, the deep sea is the only major environment in the world's ocean for which we have no data for the reproductive cycle of asteroids.

INTRODUCTION

Implicit in some recent models of the dynamics of planktonic systems, for example that of Steele & Frost (1977) is the concept that filter-feeding copepods may be scaled by size when considering feeding in relation to the size composition of their paniculate food. For a particular organism ingestion of phytoplankton has been considered to be a function of its own weight and the size composition of the phytoplankton available to it. Such scaling has been assumed to occur both in an intra- and interspecific sense, with model development involving a ‘large’ copepod {Calanus) able to feed and grow more efficiently on ‘large’ cells (diatoms) and a ‘small’ copepod {Pseudocalanus) better adapted to feed on ‘small’ cells (flagellates). However, although the general relationship between growth and metabolic rate and body size is widely accepted (Banse, 1976; Fenchel, 1974) this relationship between dietary particle-size composition and size of organism has remained a working hypothesis with little experimental support..

INTRODUCTION

Lincoln (1979) stated that ‘four species (of Gammaropsis Liljeborg) are reported from the British Isles, Gammaropsis maculata (Johnston), G. palmata (Stebbing & Robertson), G. nitida (Stimpson) and G. sophiae (Boeck)’. In fact, six species of Gammaropsis have been reported from the British Isles in the literature, the records of G. lobatus (Chevreux) (Spooner, i960) and G. melanops (Sars) (Jones, 1948) having apparently been overlooked by Lincoln (1979). Spooner's (1960) material is apparently no longer extant, but the material attributed to G. melanops by Jones (1948) has been re-examined by us and found to be referable to G. lobata. Recent collections of G. lobata from the west coast of Ireland confirm a rather wide distribution of this species in the southwest of these islands.

Five species of Gammaropsis are therefore now known from these islands, and G. melanops can, at least for the present, be deleted from the British and Irish list of species.

Lincoln (1979) was unable to examine any British material of G. sophiae, everything labelled as such, in the material examined by him (including the Norman collection at the B.M.N.H.)* being referable to G. nitida. He therefore figured the species from West African material. G. sophiae is quite widespread along the southwest coast of Ireland and since it differs somewhat from the material described by Lincoln (1979) it is figured herein from the Celtic Sea.

Krapp-Schickel & Myers (1979) reviewed the Mediterranean species of Gammaropsis and segregated the species into two groups, group ‘A’ species characterized by the possession of a toothed urosome, toothed coxa 1 and long acute epistome, and group ‘B ‘ species characterized by having a smooth urosome, smooth coxa 1 and short epistome.

INTRODUCTION

Members of the leucosiid genus Ebalia are typical oxystomatous crabs which live on subtidal coarse sediments at depths ranging from a few metres to over 2500 m. Although this genus has an almost worldwide distribution, no studies of the population biology of any species has been made.

Five species of Ebalia occur round British coasts (Ingle, 1980), four of which have also been recorded from the Clyde Sea area (Allen, 1967). During dredging surveys in this region, a sizeable population of Ebalia tuberosa (Pennant) was located in the vicinity of the University Marine Biological Station on Great Cumbrae Island, and regular sampling of this population over a period of two years provided the data on which this study is based.

Apart from a few references to the occurrence of female crabs in berry (Lebour, 1928a, b; Marine Biological Association, 1957; Allen, 1967) and to the occurrence of larvae in the plankton (Jorgensen, 1923, 1925; Lebour, 19286; 1947; Rees, 1952; Williamson, 1956; Marine Biological Association, 1957; Bruce, Colman & Jones, 1963; Crothers, 1966), no other information on the population biology of E. tuberosa is available.

INTRODUCTION

Until recently saturated sterols – stands – were not thought to play an active biochemical or physiological role in organisms. They were generally considered to be diagenetic products of the microbiological reduction of the common natural product Δ5sterols and as such have been reported in sediments (e.g. Gaskell & Eglinton, 1975).

Prior to the regular use of capillary gas liquid chromatographic (GLC) and gas chromatographic-mass spectrometric (GC-MS) techniques the majority of sterol analyses had been performed on packed column GLC. It is now well known that in the analysis of some of the complex mixtures of sterols which commonly occur in the marine environment, the use of packed column GLC techniques alone is an inadequate procedure (e.g. Ballantine; Roberts & Morris, 1976; Ballantine et al. 1977). Certainly complete resolution of the sterol-stanol pairs cannot normally be achieved on packed columns and identification of the components within each peak has to be made by multiple mass spectral scans across each peak (Ballantine et al. 1976). With the advent of techniques with better resolving powers, significant amounts of natural product stands have been found in a wide spectrum of phyla including molluscs, sponges coelenterates, echinoderms, annelids and tunicates (Morris & Culkin, 1977 and references therein; Ballantine et al. 1976; Ballantine, Lavis & Morris, 1979, 1981; Voogt, 1976; Ballantine et al. 1977; Ballantine et al. 1978; Gupta et al. 1979). In some instances the stanols have been found to account for over 50% of the animals component sterols.

As the sterol profile of marine invertebrates becomes better understood it is clear that stanols are important biochemical constituents of many of these organisms; but little is known of their significance in any biochemical or physiological role.

INTRODUCTION

Both the inner and outer epithelia of salps propagate action potentials (Mackie & Bone, 1977). Skin pulses in the outer epithelium underlying the test (OSPs) evoked by mechanical or electrical stimulation of the epithelium ‘enter’ the brain and may alter the regular rhythmic locomotor activity (Mackie & Bone, 1977; Anderson et al. 1979). The route of'entry’ has not been determined, but has been assumed to be via the axons of the scattered mechanoreceptor sensory cells lying in the outer epithelium. The OSP system would thus operate to extend the sensory field of such cells, as in the appendicularian Oikopleura (Bone & Mackie, 1975; Bone & Ryan, 1979) where two sensory cells are coupled to a conducting epithelium.

Salps alternate generations between the solitary asexual oozooid, and the aggregated sexual blastozooids (budded from the stolon of the oozooid). The linked blastozooids form chains, along which OSPs pass to regulate the locomotor behaviour of individual zooids in the chain. The zooids are not linked by gap junctions, and OSPs pass along the chain in a complex.manner, involving alternating epithelioneural and neuroepithelial synapses (Bone, Anderson & Pulsford, 1980; Anderson & Bone, 1980). The OSP system of the oozooid generation is less well understood, although it is known that OSPs in the outer epithelium of the oozooid propagate into the stolon, where they have been studied by Anderson (1979). This paper shows that oozooids possess a similar system of neuroepithelial synapses to that of blastozooids, and that these ‘ drive’ OSPs in the same way as occurs during the regenerative transmission of OSPs along the blastozooid chain.

INTRODUCTION

Marine bivalve molluscs have in recent years attracted considerable attention for a variety of reasons, not least of which is their importance as a source of food for man. Much of this research has concentrated on studies of reproduction; Mytilus viridis (India: Nagabhushanam & Mane, 1975), M. edulis aoteanus and Aulacomya maoriana (New Zealand: Kennedy, 1977);Choromytilus meridionalis and Aulacomya ater (South Africa: Berry, 1978); Mytilus (= Perna) perna (Brazil: Lunetta, 1969); M. edulis planulatus (Australia: Wilson & Hodgkin, 1967); Mytilus californianus and M. edulis (U.S.A.: Hines, 1979); Mytilus galloprovincialis (France: Lubet, 1959) and M. edulis (U.K.: Chipperfield, 1953; Seed, 1975; Bayne et al. 1978). A review of the literature revealed that in the majority of studies cytology was used as a descriptive tool for the ‘staging’ (Chipperfield, 1953; Lubet, 1957; Seed, 1975, 1976) of the developing gametes and certain anomalies were apparent with regard to the nomenclature of the connective tissue matrix of the mantle lobes.

INTRODUCTION

The common mussel Mytilus edulis L. is one of the most successful shore molluscs. It is widely distributed in the northern hemisphere and is abundant not only in the most sheltered bays and loughs but also in conditions of extreme exposure (Lewis, 1964; Seed, 1976). Attachment to the substratum is by means of the proteinaceous byssus complex, the strength of which has been shown to vary seasonally (Price, 1980b). This variation could be a response to seasonal fluctuations in wave action, as suggested by Pieters et al. (1978), or may result from the seasonality of other environmental variables. Some of these, e.g. salinity and sea temperature, have been shown to influence byssus production (Glaus, 1968; Van Winkle, 1970; Allen et al. 1976), Phytoplankton density, spawning and the reduced ‘scope for growth’ during winter months (Bayne & Widdows, 1978) may also play a role in determining byssus strength.

In the present study, the relationships between byssal attachment strength and environmental and other variables are examined in a population of mussels on the South Wales coast.

INTRODUCTION

Estimations of the growth of bivalves have traditionally been determined from measurements of animals collected on a regular basis from natural populations. Generally size frequency distributions have been analysed or growth rates estimated from measurements of the distances separating the annual rings (Hughes, 1970; Seed & Brown, 1978; Taylor & Venn, 1978). While both methods provide valuable information on shell growth, a more direct approach is to investigate experimentally the growth of individual animals held in cages and to follow the seasonal changes in the dimensions of their shells.

The queen scallop Chlamys opercularis (L.) is found in large numbers in areas around Great Cumbrae Island in the Firth of Clyde where they form the basis for a small local fishery. In 1979 the British Steel Corporation started operating a deep-water terminal at Hunterston unloading and loading iron ore and coal. It was envisaged that accidental spillage of material during transfer from the vessels to the shore might affect the queen scallop populations in the area.

INTRODUCTION

In the Bivalvia the two valves and connecting ligament are parts of a single shell each composed of three layers secreted by continuous surfaces of pallial epithelium as shown in Fig. 1. The superficial periostracum is formed in a groove at the base of the inner side of the outer (secretory) fold of the mantle margin and is continuous around the pallial lobes and within the embayments at each end of the ligament. The outer calcareous (prismatic) layer of the valves and the anterior and posterior outer (lamellar) ligament layers are formed by the outer surface of this outer fold which hypertrophies in the depths of the embayments where ligamental material is secreted. The inner calcareous (usually nacreous or porcellanous) layer of the valves is produced by the general pallial surface except along a mid-dorsal strip, the mantle isthmus (Owen, Trueman & Yonge, 1953; Yonge, 1953) which secretes the inner (fibrillar) ligament layer.

INTRODUCTION

Cephalopods are among the most active and agile animals in the oceans. They are all predators and many pelagic species are capable of high swimming speeds.

The morphology of the gills (ctenidia) and heart and vascular systems in cephalopods are suggestive of a high efficiency in respiratory gas exchange and internal blood gas transport.

The present study reports on resting (standard) values of O2-uptake in relation to body size and ambient water O2-tension in the common cuttlefish, Sepia officinalis.

INTRODUCTION

The small squid Alloteuthis, and the larger Loligo have elongate mantles chiefly made up of two distinct types of circular muscle fibres, partitioned by thin sheets of radial muscle fibres (Bone, Pulsford & Chubb, 1981).

Nerve terminals on both types of circular fibre and upon radial fibres contain 50 nm electron-lucent vesicles; preliminary pharmacological investigations (Bone & Howarth, 1980) indicate that L-glutamate is the excitatory transmitter at the terminals upon the circular fibres. In other cephalopods, such as Sepia, and the squids Lepidoteuthis and Taningia (Clarke & Maul, 1962; Clarke, 1967) there are in addition to the circular and radial fibres, layers of longitudinal muscle fibres in the mantle. Such longitudinal fibre layers are lacking over the greater part of the mantle in Alloteuthis and Loligo. In this note, we show that they are present only around the anterior margin of the mantle in these two squid, and that both these anterior longitudinal fibres and the radial fibres of the mantle are insensitive to L-glutamate, but contract in response to acetylcholine, as do the retractor muscles of the head and arms, and the siphon muscles.

INTRODUCTION

It has long been known that the ears of clupeoid fishes differ from most other fish in that they have a gas-containing bony bulla associated with each ear (for references to early work see Allen, Blaxter & Denton, 1976). The expansion and contraction, with changing pressure, of this gas causes liquid to flow in the ear and lateral line (Gray & Denton, 1979; Denton, Gray & Blaxter, 1979) thus causing displacements (Best & Gray, 1980) and excitation (Denton & Gray, 1980) of the utricular maculae; it also causes excitation of the lateral line neuromasts (unpublished). Only a small fraction of the alternating liquid flow from the bullae passes through the pars inferior of the labyrinth (Gray & Denton, 1979). Furthermore, in larvae, when the utricular structures can be seen to move vigorously with an alternating pressure the saccular otolith is not seen to move (Blaxter, Denton & Gray, 1981).

INTRODUCTION

The food and feeding habits of rays (genus Raja) have received more attention than other aspects of their biology. Being nocturnal feeders (Bigelow & Schroeder, 1953), they have been thought to locate food by smell rather than by sight (Steven, 1930, 1947). More recently, the ability of the electric receptors to detect even weak action potentials has been linked with food foraging (Kalmijn, 1966). Wilson (1953) observed that the behaviour of Raja while apprehending prey was similar to that of Torpedo spp. The functional advantages of a ventral mouth as an adaptation to bottom feeding have been stressed by Alexander (1970).

Day (1880–1884) recorded that rays ate molluscs, crustaceans and fish. That the young of Raja clavata, R. montagui (as R. maculata), R. naevus and R. brachyura feed on crustaceans was observed by Clark (1922). Steven (1930, 1932, 1947) confirmed this in a wider age sample of the same species, adding that juveniles which ate amphipods and crangonids later changed to Upogebia, Portunus and Corystes cassivelaunus, whereas the adults were highly piscivorous and sometimes cannibalistic. Both Clark and Steven obtained their fish close to Plymouth. Lazzareto (1964) and du Buit (1969), largely corroborating the above, included polychaetes in the list of food items but specified no differentiation according to size.

Holden & Tucker (1974), recording only presence or absence of food items, studied R. clavata, R. brachyura, R. montagui and R. naevus from a much wider area.

In cartilaginous fish, holocephalians and elasmobranchs, the endolymphatic system of the inner ear generally communicates with the exterior via the endolymphatic ducts. The openings of the ducts on the dorsal side of the head were known already by eighteenth-century anatomists (Retzius, 1881). In certain elasmobranchs mineral particles from the environment pass into the inner ear through the ducts. Stewart (1906) described presence of sand grains in the membranous labyrinth of the shark, Squatina. Nishio (1926) found black volcanic particles of varying sizes in the endolymphatic duct, the sacculus and the lagena of Squatina angelus and the ray, Torpedo ocellata, from the gulf of Naples.

I have studied the inner ear of two species of electric rays, Torpedo nobiliana and T. marmorata. Considerable amounts of fine sand grains are found in the endolymphatic system of both species. The mineral particles are kept together by a gelatinous material or occur free in the endolymph. The size of the sand particles varies between 10 and 400μm. The grains are white or transparent, yellow, brownish or black. Mineralogical analysis with a polarizing microscope reveals that 85–90% of the particles consist of quartz, 5–10% of calcium carbonate and less than 5% of an unidentified opaque mineral, possibly corroded felspar. The grains are irregular with rounded or sharp edges. They differ in appearance from the round or lens-shaped concentrically layered aragonite octoconia found in the labyrinth of most elasmobranchs (Retzius, 1881; Nishio, 1926). The present findings seem to be consistent with the results by Stewart (1906) and Nishio (1926) suggesting that certain psammophilous elasmobranchs lack the ability to produce calcium carbonate otoliths and compensate for this by uptake of sand grains through their endolymphatic ducts.

Many pinnipeds travel long distances between breeding and feeding grounds in some cases showing remarkable homing abilities (James & Dykes, 1978). Very little is known about the methods they use to plot their course but if they were aware of their rate of movement, this ability could conceivably assist them. The following procedure which was undertaken with a captive male harbour seal (Phoca vitulina Linnaeus) demonstrated that the animal was able to determine his swimming speed.

The seal was first trained to swim at any speed through ten hoops 48 cm in diameter submerged at equal intervals around the periphery of an 8 m oval tank filled with sea water to a depth of 1.2 m. Each trial consisted of one circuit of the tank, and always began at the same hoop. A screen preventing the seal from going through this start hoop was removed to indicate the onset of each trial. The seal was then trained to swim the 17 m course maintaining a speed of 6 km/h. The experimenter observed from a bridge suspended over the tank, and measured the animal's speed by listening to a series of tones. These tones were audible only to the experimenter and were timed such that if the seal were swimming at 6 km/h, he would reach each hoop at the same moment the experimenter heard the tone. A buzzer was sounded whenever the animal swam at less than the required speed, and a whistle was blown if he were moving too quickly.