Examination of the intertidal distributions of isozyme and pedal colour phenotypes of Actinia equina L. has shown that anemones displaying column coloration ranging from red to brown, are divisible into three, ecologically distinct forms in Britain, which we currently interpret as being morphs of a single species. These are termed the upper (U), mid (M) and lower (L) shore morphs, which are relatively most abundant on the upper mid, lower mid and low shores, respectively; not all morphs are represented on some shores. The U, M and L morphs may be separated on the basis of their hexokinase and malate dehydrogenase phenotypes. The U morph is homozygous slow and fast respectively, the L morph is slow and fast respectively whilst the M morph is heterozygous at both loci. Data on linkage of pedal disc colour and alleles at a tetrazolium oxidase locus, and of an association between alleles at the hexokinase locus and those at an esterase locus, are given.

INTRODUCTION

Wild-caught squids have seldom survived for very long in laboratory aquaria. Tardent (1962) maintained Loligo vulgaris Lamarck, 1789 for a maximum of 60 days. Choe & Oshima (1963), Choe (1966) and LaRoe (1971) reared squids of the genus Sepioteuthis from eggs to adult size. Between 1975 and 1982 several successful attempts to maintain Loliginidae (e.g. Matsumoto, 1976; Hanlon, Hixon & Hulet, 1978, 1983; Yang et al. 1980, 1983) and Ommastrephidae (Flores et al. 1976; Flores, Igarashi & Mikami, 1977; O'Dor, Durward & Balch, 1977) were made. But to date only ten squid species have been maintained for more than forty days (review: Yang et al. 1980; Boletzky & Hanlon, 1983). Loligo opalescens Berry, 1911 holds the record for longevity in captivity at 233 days from egg to adult (Yang et al., 1983).

Most current literature concerning moult control in crustaceans concludes that initiation of premoult is controlled by changes in the level of moult-inhibiting hormone (MIH) produced by the eyestalk neurosecretory organs. MIH is thought to act by repressing the secretory activity of the Y-organs, preventing increases in circulating ecdysteriod levels, necessary for moulting (see Kleinholz & Keller, 1979). This hypothesis is based upon the observation that eyestalk removal, by removing the source of MIH, leads to accelerated moulting (see Passano, 1960; Vernet-Cornubert, 1961; Sochasky, 1973, for reviews), and it survives despite many contrary reports indicating that moulting is unaffected by eyestalk removal (Sochasky, 1973). Perhaps the best known of the most contradictory data of this nature have been reported for Palaemon serratus for which Drach (1944, 1947), Panouse (1946, 1947) have shown that eyestalk removal generally accelerates moulting in this species. In contrast, Scheer & Scheer (1954) and Carlisle (1953) demonstrated no moult inhibition in this species following eyestalk removal.

On examining a sample of tanaids from the bathybenthos of the Rockall Trough, part of an extensive collection made by the Scottish Marine Biological Association (S.M.B.A), some very thin translucent tubes were noted. In these could be discerned several tanaids, one of which was extremely elongate. These proved to belong to a new genus, the adults of which were even more filiform than Filitanais moskalevi Kudinova-Pasternak, 1973. Scrutiny by the authors of other Rockall Trough samples has resulted in more adult specimens of this remarkable new tanaid being obtained. In this paper it is diagnosed and described, together with a discussion of its biology.

Strontium was shown to occur in marine organisms in the early part of the nineteenth century (Moretti, 1813; Vogel, 1914). However, since early detection methods have relied upon chemical separation, accurate quantitative determination of small amounts of strontium, has presented many difficulties due to the chemical similarity of strontium and calcium. During the last 30 years a number of relatively sensitive methods have been developed (Smales, 1951; Thompson & Chow, 1955; Bowen, 1956; Hummel & Smales, 1956; Odum, 1957b; Sugawara & Kawasaki, 1958; Culkin & Cox, 1966; Riley & Segar, 1970; Gibbs & Bryan, 1972). Towards the beginning of this period, Vinogradov (1953) made an extensive review of the chemical data on the marine biota. Due to the limitations mentioned above there was relatively little information available on the occurrence of strontium.

The shells of marine invertebrates grow incrementally (Wilbur, 1972). When a section of shell is observed under the microscope, the increments are often visible, separated by fine lines (Fig. 1). Studies of these phenomena have focused chiefly on the periodicity of increment and growth-line formation, principally because of its geological or archaeological application as a ‘biological clock’ (e.g. Wells, 1963; Koike, 1973).

INTRODUCTION

The shore crab, Carcinus maenas (L.), rapidly clears bacteria from the circulation to the tissues by virtue of the phagocytic and clumping capacity of circulating haemocytes and fixed phagocytic cells (Smith & Ratcliffe, 1978, 1980a, b; White & Ratcliffe, 1982). If re-infection resulting from the re-entry of sequestered micro-organisms into the circulation is to be prevented then the host must eliminate or incapacitate the foreign particles in some way. The migration of laden host cells to the exterior does not appear to be an important means of disposal of segregated non-self material in the Crustacea (Merril, Mongeon & Fisher, 1979; White & Ratcliffe, 1982), so that the ability to resist infection must reside with the cellular killing capacity, perhaps augmented by humoral antibacterial activity. Indeed, our earlier observations on the disappearance of bacteria from C. maenas gills seem to indicate that their loss resulted from the lytic action of host haemocytes (White & Ratcliffe, 1982), as does the elimination of micro-organisms from the hepatopancreas of the crayfish, Parachaeraps bicarinatus (McKay & Jenkin, 1970a).

Previous work has shown that three ecologically disinct morphs can be identified amongst beadlet anemones, Actinia equina L., ranging in column coloration from red to brown (Quicke, Donoghue & Brace, 1983; Quicke & Brace, 1984; Quicke et al. 1985). Each is adapted to a different inter-tidal range, and is characterized by a multi-locus gene complex, which includes loci encoding a number of metabolically important enzymes, pedal disc coloration and probably strength of pedal attachment. They have been named the upper (U), mid (M) and lower (L) shore morphs, and are relatively most abundant on the upper mid, lower mid and low shores respectively. Members of the U morph are typically homozygous slow and fast at a hexokinase locus and a malate dehydrogenase locus respectively, whereas those of the L morph are typically homozygous for the other allele at each of these loci; M morph individuals are heterozygous at both.

INTRODUCTION

A common characteristic of alga-invertebrate symbioses is their specificity; in general, a given symbiotic invertebrate species forms a stable association with just one species or genus of alga. One approach to examine the basis and significance of the specificity is to compare the performance (i.e. survival, growth and reproduction) of invertebrates experimentally infected with a range of algae. To date, such investigations have been made almost exclusively with algae which do not naturally form an association with the host species (e.g. Schoenberg & Trench, 1980; Mews & Smith, 1982; Douglas, 1983), and the relevance of the conclusions to the natural situation is not always clear.

The genus Echinus is common throughout the entire northern North Sea. Echinus esculentus L. predominates in the shallow water off the eastern Scottish coast down to 100 m, while the small variety of Echinus acutus var. norvegicus (Düben and Koren) is rarely found in depths of less than 100 m and is most commonly located in the north-eastern area of the North Sea (Cranmer, 1985).

We have recently assessed phenotypic and genotypic diversity within an aggregation of the intertidal beadlet anemone, Actinia equina L., located at Burniston in N. Yorkshire, on the east coast of Britain (Quicke & Brace, 1983). The study was undertaken in order to provide information relating to the role of intraspecific aggression (Bonnin, 1964; Brace & Pavey, 1978; Brace, Pavey & Quicke, 1979) in modifying the spacing of individuals. Limited work on the genus Actinia (A. tenebrosa Farquhar) has already indicated that whilst genetically dissimilar anemones display aggression towards one another, auto-genotypic aggression is minimal (Ayre, 1982), as is also the case for the clonal anemone, Anthopleura elegantissima (Brandt) (Francis, 1973a,b,1976). We therefore anticipated that aggressive interactions would promote auto-genotypic clustering, initiated by the local settlement of the asexually produced, brooded young (Carter & Thorp, 1979; Gashout & Ormond, 1979; Orr, Thorpe & Carter, 1982), and that correspondingly, genetic diversity within aggregations of anemones would be low.

Although the distribution of most coastal and oceanic fishes of the seas of northern Europe is relatively well-known extensions to known range are reported with moderate frequency as vagrant specimens are found or captured and recorded. Possibly it is partly because the fish fauna is well documented, with reliable literature to permit identification, that rare or unusual fishes are quickly recognized and attempts made to identify them. Most such specimens are housed in museum or other institutional collections and thus information about them can be retrieved long after their capture. However, the circumstances of the present report which records the stranding of a white marlin T. albidus Poey, 1860 on the Lancashire coast at Morecambe Bay are somewhat unusual in that the whole specimen was eaten and the only evidence remaining are two photographs and a small piece of skin. In view of the interest of this occurrence, which represents a northward extension of the range of the species by several hundred miles, as well as the first report of its occurrence in British seas, full documentation is given here and both available photographs are reproduced.

Introduction

The morphology of the Cardiidae is extremely variable and their taxonomy is uncertain because of the difficulty in recognizing the differences that are genetic and the variations that are due to environmental conditions. This is the reason why Cerastoderma glaucum (Bruguière) (Fig. 1) and C. edule have been for a long time considered as ecotypes of one species or two taxons belonging to a super-species C. edule (Lubet, 1976).

In the course of a study by Gibbs (1984) of the reproductive biology and the population dynamics of the bivalve Abra tenuis (Montagu) collected from the Fleet, a brackish water lagoon in Dorset, and from the Plym Estuary, Plymouth, a number of species of apparently pathogenic larval digeneans was found. These could not be satisfactorily identified from their larval characters alone, and following collaboration with Professor J. Llewellyn (personal communication) it was decided that they should be made the subject of a further study.

Members of the genus Phascolion Théel are probably the most familiar of sipunculans because most species inhabit the empty shells of molluscs and other similar structures and are therefore easily collected in dredge samples. Although the genus is represented in most seas and depths, few species have been investigated in detail and much of our knowledge is based on studies of the widespread Atlantic species P. strombi (see Åkesson, 1958; Hylleberg, 1975; Kristensen, 1970; Wesenberg-Lund, 1929). P. strombi is known to be remarkably plastic in many of its characters, particularly external, to the extent that Gerould (1913) was able to distinguish seven varieties in the western Atlantic region alone. Much of the variation in the size and colour of P. strombi, and in the form of the skin papillae, especially those generally termed ‘holdfasts’ or ‘adhesive papillae’, may be attributable to the size and type of shelter that is inhabited but experimental evidence is lacking. It follows that a similar degree of external plasticity to that recognised in P. strombi must be assumed for most, if not all, Phascolion, presently totalling around 45 species. Many Phascolion species have been erected on single or just a few specimens showing only slight differences of dubious systematic significance.

Taxonomically, the genus is very difficult and no satisfactory key to the species has yet been devised. As a first step, there is a need for definitions of subgenera, preferably based on internal characters which are not subject to environmental influences. To this end, the retractor systems of the north-east Atlantic species described below have been studied and compared with the type specimens of species from other areas.

Culture of mussels, Mytilus edulis L. is a developing industry in Irish coastal waters. Settling larvae are collected on 10 m long ropes which are suspended from g.r.p. rafts at a density of five ropes per square metre or from paired long lines, buoyed by plastic floats, at a density of some four hundred ropes per hundred metres. Mussels are harvested after eighteen months when the ropes yield up to 5 kg live weight per metre or approximately 250 kg m−2. Commercial culture at this density clearly exerts a considerable effect on energy and nutrient flow in the coastal ecosystem. In order to quantify the role of cultured mussels we investigated the carbon and nitrogen budget for production rafts and long lines in Killary Harbour, a fjordic inlet on the Irish west coast (Rodhouse et al. 1984) and compared these with estimates for the wild population on the shore.

INTRODUCTION

Venus striatula (da Costa) (= Venus gallina L.) occurs in high densities in shallow water on a bottom of clean fine sand in the Bay of Douarnenez. The environmental conditions are characterized by an obvious sediment instability due to a high exposure to westerly swells (Guillou & Le Moal, 1978). This species is preferentially distributed in the fine sands (Petersen, 1913; Thorson, 1957), but is relatively tolerant towards certain ecological factors and so is sometimes found in very muddy sediments. It also shows an extended latitudinal range, since it is recorded from the Lofoten Islands to the Canaries, in the Mediterranean and the Black Sea (Tebble, 1966).

Certain shallow-water embayments (< 1 m) along the Swedish west coast have recently been documented as highly productive areas for both infauna (Moller & Rosenberg, 1982, 1983) and mobile epifauna (Pihl & Rosenberg, 1982) as well as important nursery and feeding grounds for fish (Pihl, 1982; Evans, 1983). The present report, dealing with Nereis diversicolor O. F. Miiller, complements the earlier descriptions of recruitment, abundance and production of the dominant infauna species Mya arenaria L., Cardium (Cerastoderma) edule L. and Corophium volutator (Pallas) in these rather sheltered shallow areas in the archipelago of western Sweden.

The following three species of grey mullet (Mugilidae) are recorded by Wheeler (1978) for the waters of north-western Europe: thick-lipped mullet, Chelon labrosus (Risso, 1826); thin-lipped mullet, Liza ramada (Risso, 1826) and golden mullet, Liza aurata (Risso, 1810). Liza ramada was obtained in relatively large numbers during the course of extensive sampling of the material collected on the intake screens of power stations in the Bristol Channel and Severn Estuary (for details of other studies see e.g. Claridge & Gardner, 1977, 1978; Titmus, Claridge & Potter, 1978; Abou-Seedo & Potter, 1979; Claridge & Potter, 1983, 1984). Since there is apparently no detailed information on the biology of the thin-lipped mullet in the estuaries of north-western Europe based on regular frequent collections, the power station material was used to provide data on seasonal and annual abundance, size composition, growth and lip depth of this species in the Severn Estuary and Bristol Channel. Comparisons have been made between these data and those obtained for C. labrosus from the same environments and more particularly from outside the area at Pembroke where much larger collections of this latter species were taken.

The oxygen-carrying capacity of the blood of decapod crustaceans fluctuates widely. Salinity stress results in doubling of haemocyanin concentration within 24–48 h in Carcinus maenas (Boone & Schoeffeniels, 1979) while in the lobster, Homarus gammarus respiratory pigment levels are very low prior to and following moulting (Spoek, 1974). In general, however, the most important factor regulating haemocyanin concentration is nutritional state. Following starvation low values are recorded (Wieser, 1965; Uglow, 1969; Djangmah, 1970) and there are concomitant reductions in ventilation, oxygen consumption and cardiac output (Ansell, 1973; Marsden, Newell & Ahsanullah, 1973; Wallace, 1973). The interrelationships between these events are poorly understood.