Tributyltin (TBT) pollution has exterminated populations of the dog-whelk Nucella lapillus along most of the north Kent coast (Thames Estuary) but the species survives as a small enclave around the North Foreland. Males in this enclave exhibit an unusual defect involving the non-development or partial development of the genital system: about 10% lack penes, or have undersized penes, and their gonoducts (vas deferens and prostate) are incompletely developed; in some cases, spermatogenesis appears to be retarded. Laboratory-bred animals display the same characters. This deficiency (‘Dumpton Syndrome’) is manifest also in the atypical development of male sex organs on the females (‘imposex’) induced by exposure to tributyltin (TBT). The evidence points to Dumpton Syndrome being a genetic disorder which has lessened the sterilizing effect of imposex and thereby has permitted the survival of this isolated enclave in an area of high TBT pollution.

The nematode Mesacanthion diplechma Southern is relatively rare in sediments of the Southern Bight of the North Sea and the Dutch Delta. Strangely, it is about the only free-living nematode found in the stomachs of the sand goby Pomatoschistus minutus Pallas from the same general area and even more peculiarly several hundred animals were found in sand gobies from the central part of the Oosterschelde. The large size of the nematode and its preference for the superficial sediment layers are probable causes for the first observation. For the second observation there is at present no explanation that can be substantiated. Some nematodes are known to aggregate on dead animals and possibly the Oosterschelde gobies may have been feeding on such an aggregation.

The mean annual towing speed of the Continuous Plankton Recorder (CPR) varied systematically between 1946 and 1991. By mounting a pressure transducer on the CPR to record towing depth, it was shown, however, that changes in towing speed did not cause a significant change in towing depth, although the mean towing depth (6–7 m, SD=l-7 m, N=77) was shallower than the previously assumed towing depth of 10 m. Thus the observed changes in towing speed are unlikely to have caused discontinuities in the CPR time-series by affecting sampling depth.

Long-term data sets play an important role in attempts to understand the causes of fluctua- tions in plankton abundance. The Continuous Plankton Recorder (CPR) survey provides multi- decadal information on plankton abundance in the North Sea and North Atlantic (McGowan, 1990), and is one of the longest standing marine plankton abundance time-series. However, while the CPR time-series has great potential, as with all other data sets spanning many years, questions may be asked regarding the consistency with which the data have been collected and hence the true continuity of the time-series.

Ensis directus (Bivalvia: Solenidae) was noted for the first time along the French coast of the North Sea in June 1991. High numbers of post larvae after a period of northerly winds indicate that settled larvae originated from adult populations in Belgian or Dutch coastal waters. Future dispersal of Ensis directus could be used as a biological tracer of coastal water movements between the Southern Bight of the North Sea and the English Channel.

The American jack knife clam, Ensis directus (Conrad, 1843), synonym Ensis americanus (Binney, 1870)sensu van Urk (1964,1972), was discovered in Europe in the German Bight for the first time in June 1979 (Von Cosel et al., 1982). This species is assumed to have been transported in its larval stage by a ship containing ballast water. Considering the dimensions of the specimens, this probably happened in the first half of 1978 (Von Cosel et al., 1982; Mühlenhardt-Siegel et al., 1983). Since then this species has spread rapidly in the North Sea in subtidal and intertidal areas. Dense populations were found along the German coast within a few years (Von Cosel et al., 1982; Mühlenhardt-Siegel et al., 1983; Swennen et al., 1985). In 1986 Ensis directus was reported from the north and east Danish coasts as far as the Belgian coast (Kerkhof & Dumoulin, 1987) (Figure 1). Since then no new records have been reported.

Chromosomes of Haliplanella luciae (=H. lineata) (Verrill) were studied by a simple method that involved examination of Giemsa-stained preparations. The preparations were made from early embryos after fertilization in the laboratory. This is the first report of chromosome number for the acontiate sea anemones. A modal diploid number of 32 chromosomes was observed in metaphase plates. The method reported here is applicable to studies of chromosomes of other Actiniaria in which external fertilization occurs, with mature gametes being released from individuals of both sexes.

The retina of larval herring (Clupea harengus L.) contains only cones, with rods recruited progressively from about eight weeks onwards. The molecular species composition of phospholipids from the eyes of herring of different ages was determined to find whether the appearance of di-docosahexaenoyl molecular species (di22:6n-3) of phospholipids, which are characteristic of rod outer segment membranes in higher vertebrates, coincided with the appearance of rods. In the eyes of larval herring (cone-only retina) di22:6n-3 molecular species comprised 25.9% of phosphatidylethanolamine (PE), 22.9% of phosphatidylserine (PS) and 4.2% of phosphatidylcholine (PC). In the eyes of adult herring (rod:cone ratio of about 20:1) the proportion of di22:6n-3 molecular species had increased to 49.5%, 39.0% and 16.8% in PE, PS and PC, respectively. Juvenile herring had intermediate values of di22:6n-3 phospholipids. The results confirm the hypothesis that the amounts of di22:6n-3 molecular species of phospholipids in retina increase during development as rods appear, and also show that cones contain smaller amounts of these unique lipids. Three other molecular species containing docosahexaenoic acid, 16:0/22:6n-3, 18:1/22:6n-3 and 18:0/22:6n-3 were also major components of eye phospholipids, emphasizing the important role of 22:6n-3 in vision.

The use of tetracycline marking has enabled the daily production rate of calcareous spicules in the Mediterranean calcisponge Clathrina cerebrum to be measured. Twenty-four hours after starting the experiment newly formed spicules represent about 10% of the total spicule number. No differences in this rate of spicule secretion were detected between the samples tested under light and dark conditions. The growth rate of the tetracycline-tagged spicules in Clathrina cerebrum is similar to that found for other calcispongiae using other methods.

Spicules constitute the skeleton of sponges and are the most important taxonomic character in this group. In calcareous sponges many details of the process of spicule secretion are well known (see Simpson, 1984 for review), particularly their chemical composition and crystallographic structures (Jones, 1955, 1967; Jones & Jenkins, 1970; Ledger, 1976). Ultrastructural studies were carried out on the cellular processes involved in spiculogenesis (Jones, 1970; Ledger & Jones, 1977), but little is known of the rate of spicule secretion. This phenomenon has been studied here by tetracycline marking of newly calcified spicules, triactines. Tetracycline forms complexes with calcium or other metal ions which are easily incorporated into biominerals; consequently it can be used to label the growth of biocalcified structures (Ibsen & Urist, 1962). This method is commonly used in medical research (Urist & Ibsen, 1963; Sandhu & Tonna, 1986; Milch et al., 1957; Van Linthoudt et al., 1991), and has also been employed in studies on biocalcification in marine organisms, such as echinoderms (Gage, 1992) and molluscs (Nakahara, 1961).

Histochemical techniques were used to investigate the possible role of the buccooesophageal glands in the blue mussel, Mytilus edulis L. (Mollusca: Bivalvia). No activity was observed for any of the eight major digestive enzymes tested; however, the glands contained large amounts of both neutral and acid mucopolysaccharides. These results confirm the importance of mucus in the ingestive process in M. edulis, and do not support the hypothesis of ingestion of particles suspended in water alone.

Until recently it was thought that the Bivalvia were the only class of molluscs in which some type of secretory gland of extracellular digestive function in the bucco-oesophageal region was totally absent (Table 1). However, in a study of the mode of particle ingestion in five species of suspension-feeding bivalves, an extensive glandular complex was reported in the bucco-oesophageal region of Mytilus edulis L. only (Beninger et al., 1991). Although these glands were observed to liberate secretions into the oesophageal lumen, it was not known whether they performed any digestive function.

Previously unknown in Conus (Mollusca: Gastropoda) and poorly documented in the Australian region, imposex is demonstrated in 80% of females of six Conus species from Rottnest Island, Western Australia. In no case were the effects sufficiently severe to cause sterility, and reproduction appeared normal. Specimens from the same location preserved in 1975 were unaffected. With more than 500 species, Conus is the largest genus of marine molluscs. Because many species are conspicuous, widely distributed, and occur in populations whose past densities are known, they could serve as monitors of artificially induced pseudohermaphroditism and an early warning of future population responses to pollutants in marine environments at low latitudes.

Living cells of the ciliate Mesodinium rubrum were observed and photographed during summer red-water events in the Southampton Water estuary, southern England. These blooms were characterized by increases in maximum cell diameter and range of cell size, a pronounced morphological variation of the ‘oral’ hemisphere, and the presence of free-swimming ‘fragments’ of larger cells.

Red-water occurrences caused by the planktonic, phototrophic ciliate Mesodinium rubrum (Lohmann) Hamburger & Buddenbrock, have been characterized by some of the highest recorded levels of chlorophyll and primary productivity for natural populations of marine phytoplankton (Lindholm, 1985; Taylor, 1982). However, as these events are rather unpredictable and all attempts to culture M. rubrum have failed, descriptions of the morphology of living cells have been rather limited. A study into the impact of red-tides caused by M. rubrum in the Southampton Water estuary presented a useful opportunity to observe morphological variation in living cells. Water samples were taken with a ‘Van-Dorn’ sampler, and transported in polyethylene bottles in a cool box. Living cells were observed and photographed at 400x magnification using the phase-contrast optics of an Olympus BH2 photomicroscope. Autofluorescence of living cells was examined using a Zeiss fluoresence microscope.

Underwater ultrasonography is a useful tool for studying structure and mechanical events in live, fairly large marine animals that do not possess an unduly thick, calcified integument. The limit of discrimination with present technology is about 2 mm, so fine detail is absent; the transducer has to be within 1–2 cm of the animal being studied or attenuation of the ultrasound by sea-water will restrict penetration of tissues. The non-invasive nature of the technique makes it ideal for the study of valuable or particularly delicate animals (e.g. Eledone); there would also appear to be considerable potential for use of ultrasonography as a teaching/demonstration aid in marine biology.

Solidified adhesive (cement) of three balanid barnacles (Crustacea: Cirripedia) was dissolved using different concentrations of sodium dodecyl sulphate containing a reducing agent. The proteins were separated using SDS-PAGE and blotted onto polyvinylidene difluoride membrane for sequencing. Commonly occurring bands in the cement of each species were identified. One particular protein of 39 kD, found in the cement of Balanus perforatus, has the following N-terminal sequence: TYFPVLSYG?SSSLAPVI, where the? is most likely cysteine. Quinones were not identified in the cement by either infra-red, ultraviolet-visible or solid-state nuclear magnetic resonance spectroscopy and the successful dissolution and sequencing of cement proteins mitigates against their presence. Cement contains a mixture of highly hydrophobic proteins which are cross-linked through cysteine residues. It is the combination of these two components which makes cement highly resistant to chemical degradation. As a result bacteria are usually absent from the cement, possibly further excluded from the porous core of the cement by its smooth outer crust.

Statoliths of Loligo gahi were sampled in the fishery region 45–47°S on the Patagonian shelf during September 1989. Peculiarities of the growth zones in the ground statoliths of adults are described. Maximum age of large maturing and mature females (130–160 mm of mantle length, ML) was estimated to be 325–345 d, that of large mature males (250–290 mm ML) ranged from 360 to 396 d.

The squid Loligo gahi d'Orbigny, 1835, occurs in temperate shelf and upper slope waters of the Atlantic and Pacific coasts of South America and is caught commercially by the international fleet in the southern part of the Patagonian shelf within the Falkland Islands Interim Conservation Zone (FICZ) (Roper et al., 1984; Csirke, 1987). Occasionally, dense shoals of L. gahi appear in the fishery region 45–47°S off the Exclusive Economic Zone of Argentina (EEZA) and have been caught in significant numbers by trawlers at depths of 120–150 m in September-October (Chesheva, 1990). Loligo gahi is a medium sized loliginid; in Falkland waters males attain 350 mm ML, females 210 mm ML (Hatfield, 1991), while in the fishery region 45–47°S maximum size is 260 mm and 160 mm, respectively (Chesheva, 1990). Patterson (1988) revealed two Falkland spawning stocks of L. gahi of unclear status, spring-spawners and autumn-spawners (austral seasons) and pointed out that the life span of squid of each stock lasted ~1 y. Recently Hatfield (1991) used statoliths to elucidate Patterson's (1988) estimations of age and growth of Falkland stocks of L. gahi and confirmed the 1-y duration of L. gahi's life span.

Daily increments were demonstrated in the sagittae of the lesser sandeel, Ammodytes marinus, maintained in outdoor enclosures. Daily increment formation was also inferred for wild sandeels from an analysis of changes in age composition within a series of field samples. A comparison between sagitta microstructure and morphological development of larval and juvenile sandeels indicated that the first sagitta increment was formed around the time of hatching. Yolk-sac absorption and larval metamorphosis were accompanied by changes in otolith microstructure.

The lesser sandeel, Ammodytes marinus (Raitt), is important as a prey item for many species of fish, seabirds and marine mammals (Furness, 1990) and supports major fisheries in the North Sea (Anon., 1991). However, little is known about the ecological processes affecting year-class strength in this species. Otolith microstructure has been demonstrated to be a potentially useful tool for investigating early survivorship in fishes, since otoliths may provide a chronological record of early growth and life-history events (see Campana & Neilson, 1985). This paper examines the usefulness of otolith microstructure for studies of sandeel growth, from investigations of increment periodicity and a comparison between otolith microstructure and morphological development.

In contrast to the situation found in the bivalves Barnea Candida and Spisula solidissima prophase arrested oocytes of Ruditapes philippinarum cannot be fertilized when extracted from the ovary. They must first undergo germinal vesicle breakdown (GVBD) under the influence of the neurohormone serotonin (5-HT) which drives them to a second block occurring in metaphase of the first maturation division. We used Fluo-3 to investigate the possibility that calcium was involved as a second messenger in controlling this first step in meiosis reinitiation. Our data showed that, in addition to 5-HT, ionophore, thapsigargin and the weak bases ammonia and procaine could induce prophase-arrested oocytes of Ruditapes to resume meiosis.

In this paper we report for the first time the occurrence of Parablennius sanguinolentus in mainland Portuguese waters. Since this species is common in the Mediterranean and in the Bay of Biscay, there appears to be a distributional gap along the Portuguese coast. The present finding, together with recent data on the occurrence of several other blenniids in the Atlantic coast of the Iberian Peninsula, formerly supposed to be Mediterranean endemics, stresses the urgent need for detailed zoogeographical investigations on the inshore fish fauna of south-west Europe.

Parablennius sanguinolentus (Pallas, 1811) is widespread in the Mediterranean (Zander, 1986). On the Atlantic coast of Europe, however, it was known only from the Bay of Biscay where it is abundant in some places (Motos & Ibañez, 1979), from the north-west coast of Spain (Devesa et al., 1979) and recently from the Atlantic coast of Andalucía (Spain) (Rubio, 1991). It is also very common in the Azores, Madeira and Canary Islands if one assumes that P. parvicornis (Valenciennes, 1836) belongs to the same species, but this is as yet an unresolved issue (Zander, 1979; Almeida & Harmelin-Vivien, 1983; Bath, 1990; Santos, 1992). Although Zander (1986) presented a distributional map that includes the mainland Portuguese coast, no report on the occurrence of this species was known for this area. In a survey of the literature on the blennioid fishes occurring in Portuguese waters, we could not find a single citation that could possibly be ascribed to P. sanguinolentus for mainland Portugal (Oliveira et al., 1992).

In a short communication Grahame et al. (1992) argue against our finding that Littorina neglecta Bean is an ecotype of Littorina saxatilis (Olivi) rather than a separate species (Johannesson & Johannesson, 1990b). Unfortunately, Grahame et al. (1992) have miss-represented our earlier paper, and we feel the need to refute their arguments.

In populations from north-western Europe we studied morphological characters used to separate Littorina neglecta from L. saxatilis. We found that intermediate shapes were common and, furthermore, we found no close coupling among characters used to define L. neglecta (Johannesson & Johannesson, 1990a). We further analysed the genetic variation in five strongly polymorphic allozyme loci. In four loci we found a pattern that indicated that L. neglecta is not reproductively isolated from L. saxatilis. In the fifth locus, Aat-1, we found consistent differences between populations of L. neglecta (from the low shore) and L. saxatilis (from the high shore). Similar differences were observed between low and high shore populations in Sweden where, however, no snails of neglecta-type were present.

Circumstantial evidence of mobility by the lepadomorph barnacle genus Pollicipes in the literature is supported by observations at Menai Bridge which indicate that the phenomenon is real. Although slow, movement may be in response to gravity, as a positive taxis, or light, as a negative taxis.