This paper describes the incidence and pathology of a copepod parasite (Sarcotaces sp.) in two species of deep-sea bottom-living fish. The fish Lepidion eques (Moridae) and Coelorynchus occa (Macrouridae) are common on the continental slope to the west of the British Isles at depths from about 400 to 1300 m and 700 and 2000 m respectively.

In both species the parasite was located beneath the skin. In L. eques it was found primarily on the head, whereas in C. occa it was present on the mid to lower flank, often close to the anal vent. Excision of the parasite from the host tissue showed it to consist of a pyriform sac filled with inky black fluid. Detailed histological investigations revealed the parasite wall to be a highly complex structure. Within the gut fluid shown to be of haematogenous origin, numerous copepod nauplii were often observed.

Krapp-Schickel (1975) described three closely related species of Leucothoe Leach, which together make up a Leucothoe lilljeborgi species complex (L. lilljeborgi Boeck, L. incisa Robertson, L. occulta Krapp-Schickel) in European waters. Of these, the two species L. lilljeborgi and L. incisa have caused considerable problems to taxonomists. As pointed out by Lincoln (1979), ‘There has been a lot of confusion over the identification of lilljeborgi and incisa and it would be advisable to treat earlier records with caution.’ Despite Lincoln's (1979) work, however, the problem persists, several workers (P. G. Moore & J. M. C. Holmes, personal communications) having noted forms apparently intermediate between these two species.

In order to clarify the situation, we have examined material from localities in Ireland and Britain. It is clear that the existence of apparent ‘intermediates’ is due to unfortunate choice of key characters by Lincoln, one of which requires phase contrast microscopy for correct determination. In his key to species of Leucothoe (1979, p. 172) he separates the two species by the anterodistal margin of coxa 4 being either angular (lilljeborgi) or rounded (incisa) and by the inner margin of the gnathopod 1 carpal process being either toothed (incisa) or smooth (lilljeborgi) (although in the description of L. lilljeborgi (p. 176) this process is described as weakly crenulate). Thus specimens with toothed gnathopod 1 carpal process and angular coxa 4 anterodistal margin, appear to be intermediate. It is apparent from our studies, that both L. lilljeborgi and L. incisa have a toothed gnathopod 1 carpal process, but that the structure of the teeth is quite different as revealed by phase contrast microscopy.

The laboratory at Plymouth was notified of the capture of five dolphins in a commercial trawl on 9 December 1982, three of the specimens were living and therefore immediately released. The remaining two were brought to the laboratory, identified as Delphinus delphis Linnaeus, 1758, their size and sex were recorded and the stomachs removed for examination of their contents. The exact location of capture was not recorded, but is known to be within 40 miles of Plymouth.

Reports of strandings of D. delphis collected by the British Museum (Natural History), (Harmer, 1914–27; Fraser, 1934, 1946, 1953, 1974) and more recent recorded sightings (Evans, 1980) show that the common dolphin is clearly not rare in British waters. Although the species has been recorded off all British coasts, sightings and strandings are concentrated off the south and south-west coasts of Britain and Ireland. The variation in their numbers and distribution both during this century and on a seasonal basis each year has been accounted for mainly by the fluctuation and movement of their food supply (Evans, 1980; Sheldrick, 1976).

The distribution of free neuromasts and the formation of the lateral line canals are described for two species of flatfish (plaice, Pleuronectes platessa L., and turbot, Scophthalmus maximus L.) during development from the bilaterally symmetrical larva to the bilaterally asymmetrical adult. On hatching plaice have three free neuromasts per side compared with six in turbot. After feeding is established plaice have 40–60/side compared with 20–25 in turbot. During development the ‘hillock’ of sensory cells increases in size and the cupulae grow in length. Canal formation starts later in plaice than in turbot. During metamorphosis the canal system becomes more concentrated in the upper (eyed) side of both species, but lateral line canals occur both on the head and body regions of the blind side. In plaice the tubes leading from the canals to the surface have typically one pore/tube, whereas in turbot there is much branching with 8–10 pores/tube.

This paper on Gobius niger describes the ultrastructure of free neuromast papillae of both standard and mandibular types, emphasizing the polarity of the hair cells in each row or column. Evidence to suggest a functional difference between mandibular and standard neuromasts is reviewed, together with an hypothesis concerning the developmental origin of the mandibular row, relevant to the evolution of lateral line organs in general.

A large-volume pump system (2.8 m3 min-1) for sampling fish larvae under open-sea conditions is described. Comparative efficiency trials by day and night showed that the pump was generally as efficient, or in some cases more efficient, in capturing larvae than vertically hauled 200 μm WP2 nets, though there was some evidence of visual avoidance by particular larval size classes during daylight. The pump system is particularly appropriate for investigating fine-scale vertical aggregations (1–10 m3) of larval fish in relation to the distribution of their food organisms.

INTRODUCTION

Studies of the distribution of larval fish and their food organisms in relation to physical structure in the water column require sampling techniques capable of resolving fine-scale temporal and spatial distributions. As an alternative to conventional nets, large-volume pumps, sampling at rates in excess of 1 m3 min-1; provide such a capability. Major benefits of using large pumps in addition to temporal and spatial resolution are that a wide range of sizes of plankton including larval fish can be sampled simultaneously in relation to physical and chemical properties of the water column; there is reliable control of the volume of sample filtered and problems of clogging of towed nets are avoided; long series of sequential samples can be taken in studies of small-scale distribution; and instrumentation with in situ CTD and fluorometers at the intake enables real-time control of sampling in relation to physical structure.

General engineering considerations for using such pumps have been reviewed in detail by Miller & Judkins (1981), and a particular area of application has been in power-plant entrainment studies in shallow fresh water (Portner & Rhode, 1977; Bowles & Merriner, 1978; Gale & Mohr, 1978; Ney & Schumacher, 1978; Elder et al. 1979; Leithiser, Ehrlich & Thum, 1979; Cada & Loar, 1982).

The regulation of major ions in aquatic Crustacea has been extensively studied, and it is hardly surprising that ever-present ionic constituents of sea water such as sodium, potassium, chloride, calcium and magnesium have been incorporated into highly efficient regulatory mechanisms. On the other hand, we know little of the mechanisms governing the uptake and regulation of trace elements, despite the fact that metals such as zinc and copper may be important constituents of enzymes and blood pigment.

A rare physonect siphonophore, Lychnagalma utricularia (Claus, 1879), is redescribed from 24 specimens collected in the region of the Bahamas by the submersible D.S.R.V. ‘Johnson-Sea-Link II’. It was the most common siphonophore collected by the submersible, using its sophisticated sampling techniques. The paucity of previous records for the species, and thus its apparent rarity, is probably due to the extreme fragility of the animals which causes them to disintegrate on contact with nets. The status of the second species, L. vesicularia Haeckel, 1888, is reviewed and it is concluded that it should be reduced to a junior synonym of L. utricularia.

In a study of the life-cycle of the hexabothriid monogenean Rajonchocotyle emarginata by Wiskin (1970), attempts to obtain newly hatched larvae were unsuccessful, and it was decided to make a new attempt to culture eggs and hatch larvae, at the same time investigating the effects of those factors found in other monogeneans to influence hatching, such as host mucus (see Kearn, 1974), shadows (see Kearn, 1982) and mechanical disturbance (see Bovet, 1967). The success of these renewed attempts to hatch the eggs of R. emarginata provided an opportunity to study the behaviour of the free-swimming oncomiracidium and attempts were made to relate hatching phenomena and larval behaviour to the behaviour of the host.

The effect of two 70 W underwater electric lamps on the catch rate of a commercial bottom otter trawl was determined by comparative trials both at night and in daylight. It was found that, although the overall numbers and weights of fish caught did not differ, most of the species which were caught in large enough numbers for a judgement to be made showed a reaction to light. Three species, Trachurus trachurus, Merlangius merlangus and Trisopterus minutus were attracted and four species, Eutriglagurnardus, Micromesistius poutassou, Merluccius merluccius and Limanda limanda were scared off by light.

The possible use of lights to further the development of selective commercial bottom trawling by attracting or scaring particular species is discussed.

Early investigations of the deep-sea fauna of the north-east Atlantic region resulted in many new Sipuncula species being described, notably by such workers as Koren & Danielssen (1877), Théel (1905), Sluiter (1900, 1912) and Southern (1913). Many of these species were erected from single, or few, specimens and some are still known only from the original records.

This paper examines the status of certain species, mostly the seemingly-rare golfingiids described by Sluiter and Southern (see Table 1), the types of which were deposited in the collections of the Irish National Museum, Dublin (INMD) and the Musée Océanographique, Monaco-Ville (MOMV), and presents some new observations and records. The names of taxa follow the classification of Cutler & Gibbs (1985); Nephasoma Pergament and Apionsoma Sluiter, formerly considered as subgenera of Golfingia Lankester, are now elevated to generic rank.

A survey of the ecology of the octopus Eledone cirrhosa in Scottish waters is compiled from structured interviews with fishermen, records of occurrence in traps (for lobster and crab), and a research vessel survey. This species is widespread and common throughout the inshore waters covered by fishing activity (shoreline- 140 m) on bottom types ranging through rock, stones, sand and mud. It is caught in all months of the year but is especially common inshore in the summer (July-September) and further offshore on trawling grounds in October-December. The octopus is a normal and regular predator of large Crustacea (Hotnarus, Nephrops, Cancer) caught in commercial traps but gut contents yield little identifiable dietary remains.

The feeding habits and host specificities of the Pycnogonida are poorly known. These usually small, cryptically coloured animals are difficult to observe alive and are mostly collected fortuitously in gross samples taken from trawls and dredges. Any association between the pycnogonids and their food is disrupted in the trawl. Further, the possibility that some of the pycnogonids may have been captured in the water column rather than on the bottom cannot be ascertained from trawl and dredge samples. King (1973) lists only twelve records of pycnogonids actually seen browsing on food organisms. Most occur on hydroids and other cnidarians, and all are from benthic habitats. In more recent papers, Stock reports a pycnogonid seen on a brittle star in the Seychelles (1979), feeding preferences of pycnogonids on benthic cnidarians (1978), and an association between a pycnogonid and a starfish from the Philippines (1981).

Intracellular calcium granules rich in phosphorus are found throughout the animal kingdom and occur in a wide range of different tissues (Simkiss, 1976; Mason & Nott, 1981). However, few examples of the natural occurrence of such granules in muscle cells have been recorded and thus the discovery of abundant granules composed of calcium phosphate within the muscle fibres of the polychaete Nephtys, described by Gibbs & Bryan (1984), is of considerable interest, particularly regarding the formation and function of these unusual sarcoplasmic inclusions.

The alimentary tract of the common dogfish, Scyliorhinus canicula L. was examined for the presence of gut associated lymphoid tissue (GALT). GALT was present in the buccal cavity, oesophagus, pyloric stomach, intestine containing the spiral valve, rectum and cloaca, but absent from the cardiac stomach. In the intestine containing the spiral valve the highest levels of GALT were recorded. The GALT occupied three tissue niches: as individual leucocytes in the lamina propria as accumulations in the lamina propria and as individual leucocytes in the ephithelium. Four leucocyte types were identified lymphocytes, granular cells, macrophages and plasma cells. The presence of lymphoid tissue at such high levels in the gut suggests it has a potentially important immunological function.

Serological methods for prey identification have been applied to the gut contents of a field sample of 100 Eledone cirrhosa from the Moray Firth and 7 from the Sound of Jura. Protein extracts from the crop were electrophoresed (Laurell rockets) into antisera raised against potential crustacean prey species, Cancer pagurus, Carcinus maenas, Crangon crangon, Liocarcinus spp. and Nephrops norvegicus. The strengths of the resulting reactions were evaluated on the basis of peak height, staining density and the number of homocentric peaks of immune precipitates. Sixty-two of the 100 Moray Firth animals gave a positive reaction to one or more of the antisera and the most critical assessment of the results ranked the incidence of the prey as Liocarcinus (15) > Nephrops (10) > Cancer (8) > Crangon (2) > Carcinus (0), a total of 35 reactions from 28 animals. Absence of a reaction in the 38 animals from which appreciable sample volumes were also obtained indicates that alternative prey had been consumed. Of the 7 Sound of Jura animals, 4 gave a positive reaction to Nephrops alone. A total of only 24 animals gave any indication of diet by visual recognition of remains. The value and difficulties of the methodology are discussed.

Killary Harbour is a fjord-like inlet on the west coast of Ireland and is an important site for suspended culture of mussels. As part of a study of the production ecology of the inlet, the zooplankton fauna was sampled quantitatively at two week intervals, between February 1981 and January 1982 using nets with mesh apertures of 90 and 335 μm. The dominant holozooplankton species of Killary Harbour are typical of inshore or neritic waters but there are also representatives of estuarine and oceanic faunas. Inflow of water into the bay below the surface layer of low salinity apparently maintains conditions suitable for neritic species and accounts for similarities between the zooplankton faunas inside and outside the bay. Large populations of estuarine species presumably do not develop because of the variability of freshwater discharge. During September 1981 there was evidence of an intrusion of oceanic water into the bay.

Recent investigations (Walker & Rees, 1980; Davis & Wilson, 1983b) have shown that the protobranch bivalve Nucula turgida (Leckenby and Marshall) occupies an important niche in the ecology of Dublin Bay, where it is the dominant organism over much of the southern part of the outer bay. This is an area of moderately sorted fine sand (Harris, 1980) with a pelite (silt and clay) fraction of less than 10% and a consequently low percentage of organic matter of around 1% (Davis & Wilson, 1983 b). Trevallion (1965) described the N. turgida habitat as one of firm muddy sand, adding that the animals avoided mud due to their inability to maintain position or feeding and respiratory currents and also avoided gravel due to their inability to burrow in coarse substrates.

Populations of the spirorbid Pileolaria berkeleyana ( = P. rosepigmentata) are recorded in harbours at Plymouth, Falmouth and Portsmouth and of three similarly abundant serpulids, Filogranula calyculata and Metavermilia multicristata at Abereiddy and Vermiliopsis striaticeps at Falmouth. Ship-borne introductions may well have occurred but the Abereiddy serpulids have more probably come from undiscovered populations nearby, in areas too rocky and deep for easy sampling.

INTRODUCTION

Three apparently exotic species of tubeworms, a spirorbid and two serpulids, have been established for at least five years in aquarium tanks at the Portsmouth Polytechnic Marine Laboratory. The tanks receive a continuous flow of unfiltered sea water, which is pumped from Langstone Harbour via a header tank, with little if any change in temperature. They contain many slate slabs from a flooded quarry (at Abereiddy, in South Wales), which had been opened to the sea in 1932 and is used as a harbour for small boats. The most recent transfer of slates to Portsmouth was in 1972. The slates were brought in because they bore populations of a native spirorbid (Thorp, 1975), but the associated fauna was not closely studied at that time because a general account of Abereiddy quarry and its fauna was being prepared by Hiscock & Hoare (1975).

The exotic serpulids occurred particularly on the undersides of the slates, but had not been noted by Hiscock & Hoare, nor in any other British fauna list. They also occurred on the underside of a disused heater/cooler plate supporting the slates in one of the tanks, which indicated that they had been breeding in that tank.

Two groups of mackerel (Scomber scombrus L.) are recognised by the International Council for the Exploration of the Sea (I.C.E.S.) for stock assessment purposes in the north-east Atlantic. The North Sea ‘stock’, which overwinters along the edge of the Norwegian Trench and spawns off the south coast of Norway, in the Skagerrak, Kattegat and the central North Sea (Hamre, 1980), and the Western ‘stock’, which overwinters and spawns along the edge of the continental shelf from the west of Ireland to the Bay of Biscay (Lockwood, Nichols & Dawson, 1981).