Dunal (1837) originally described the taxon now known as Dunaliella salina (Dunal) Teodoresco, 1905, as consisting of spherical or elliptical cells, red-orange to rust coloured. Teodoresco, in his definition of the species (1905) stated that the zoospores had a green chromatophore but in aged zoospores the entire body, including chromatophore, was red. Thus, by definition, any isolate of Dunaliella which is not capable of turning redorange to rust coloured should not be considered D. salina. Several strains have been reported in the literature under the name D. salina but do not meet the aforementioned criteria. These include UTEX 200 (= Cambridge 19/3), Mil'ko's strain (Mil'ko, 1963 a, b) and Strain No. 6 used by Mironyuk (Drokova, 1970; Drokova, Popova & Tupik, 1964; Drokova & Popova, 1973, 1974; Mironyuk 1969a, b; Mironyuk & Einor, 1968).

Determining the duration and timing of spermatogenesis in Mytilus californianus Conrad became key questions in our study of carcinogen-mutagen indices in the marine environment. We had postulated that the murine sperm deformation assay of Bruce, Furrer & Wyrobek (1974) should have marine analogues, and we assayed a number of marine invertebrates sampled near potentially carcinogenic waste flows, and by γ-ray dose-response experiments. Our field results demonstrated some deformation but only at a very low level (less than 5 % in Mytilus edulis L.). Development of a γ-ray doseresponse (90–900 rads) procedure for M. californianus by radium needle inserted through a drilled hole closed with a plastic plug, and subsequent biopsy of gonadal tissue at measured distances from the site of irradiation, did not show deformations from a pilot test in June 1979. If a viable dose-response procedure was to be developed it was necessary to establish seasonal reproductive timing so that specimens could be collected or cultured to maximize spermatogenesis and hence response potential, and also to establish the duration of spermatogenesis so that response measures via a gonadal tissue extraction could be appropriately timed.

In the Southern Bight of the North Sea, off the Belgian coast, exists a series of parallel sublittoral sandbanks, the Flemish Banks, situated in a southwest-northeastern direction, 15–25 km long and 3–6 km wide. They are separated by channels, 4–6 km wide, and rise about 25 m above the surrounding sea-floor (Fig. 1). These sandbanks resulted from the accumulation of sandy deposits of glacial origin sedimented by the giant stream draining the waters from the present Rhine, Meuse, Scheldt and Thames before the Flandrian marine transgression about 12000 years ago. When from boreal times onwards the North Sea became slowly inundated, a connexion existed with the small English Channel which gradually enlarged, resulting in the very strong tidal currents which are responsible for the present geomorphology of the region.

The background and aims of this study are outlined in the introductory section of the preceding paper (Vanosmael et al. 1982).

In two previous papers (Vanosmael et al. 1982; Willems et al. 1982) the macrofauna and meiofauna of a sublittoral sandbank in the Belgian coastal waters of the North Sea were described. This sandbank, the Kwinte Bank, is one of a series of parallel linear banks, the Flemish Banks, which are 15–25 km long and 3–6 km wide and rise about 25 m above the surrounding sea-floor. They are stressed, high-energy environments, subject to extreme physical disturbance by the very strong tidal currents which run parallel to the long axis of the sandbank and which put the whole upper layer of the sediment in a state of suspension at times.

In an earlier study Pingree, Pennycuick & Battin (1975) used a diffusion model to study the monthly temperature distribution and heat exchange in the English Channel. This showed that the diffusion would have to be adjusted according to the tidal ellipses for an improvement in the predicted temperature distributions, and that advection was probably an important factor at certain times of year. An attempt to use the same model for prediction of the salinity distributions was unsuccessful due partly to lack of information on run-off, precipitation and evaporation. The present study is an attempt to provide an overall monthly mean heat and salt budget for the eastern English Channel and Southern Bight of the North Sea which could serve as a preliminary to a two-dimensional mixing/advection model in which the horizontal eddy diffusion is represented as a tensor based on the tidal ellipse properties (Hunter, 1975).

A numerical model is used to derive the diurnal tides on the N.W. European Shelf. The quadratic friction term was linearized using both tidal and wind driven currents. The semidiurnal tidal currents essentially provide the friction for the diurnal tides except in a few relatively small regions (semidiurnal current amphidromes) and the Skagerrak where the wind driven currents dominate. Accurate M2 tidal currents are required for the diurnal bottom stress tensor and the M2 tidal current amplitudes are considered accurate to about 95%. Some discrepancies between model energy M2 dissipation rates and some observed estimates reported for the English Channel and Celtic Sea regions were noted.

Biological precipitation of barite (barium sulphate) is highly unusual (Bowen, 1966, p. 129). This mineral forms statoliths in certain ciliates (Hubert et al. 1975), but the only animals in which it is known to occur in significant quantities are xenophyophores, a group of giant deep-sea protozoans placed in a separate class within the Rhizopoda (Levine et al. 1980). The importance of these previously obscure organisms at abyssal, and bathyal depths in the oceans has lately become increasingly appreciated, mainly through the work of Tendal (1972, 1973, 1975a, b, 1980a, b; Tendal & Lewis, 1978).

As long ago as 1911, Henze first showed that the ascidian, Phallusia mammillata has the ability to accumulate vanadium from the surrounding sea water into its tissues. Since this report, many other workers have demonstrated vanadium as well as other metals such as iron (Koval'kii, Rezaeva & Kol'tsov, 1962; Milanesi & Burighel, 1978; Macara, McLeod & Kustin, 1979a), manganese (Noddack & Noddack, 1939) and niobium (Carlisle, 1958) in various tunicate species.

The responses of marine animals to changes in hydrostatic pressure have been widely studied (see reviews by Knight-Jones & Morgan, 1966; Fliigel, 1972; Nay lor & Atkinson, 1972). Most of these studies, however, have been concerned with invertebrates, particularly Crustacea, and few deal with fish (Gordon, 1970). Blaxter's (1978) review of baroreception summarizes recent work in this field and points out that a limitation of many experiments has been the use of sudden, rather than gradual, pressure changes. The limitation is especially true with respect to fish. This paper describes the results of experiments in which young plaice (Pleuronectes platessa L.) were subjected to hydrostatic pressure cycles of varying amplitude and frequency in order to describe the response to such pressure cycles, to determine the threshold of the response and to relate the response to the fish's behaviour in the sea.

Until recently, the most detailed and widely quoted account of the life cycle and reproductive biology of Nereis diversicolor O. F. Müller was that of Dales (1950; 1951) for a population in the Thames Estuary followed for a single season. The study combined a periodic analysis of the population structure with assessment of reproductive maturity, by gamete analysis of individual worms, and a record of larval recruitment. The conclusions reached were that worms grew to maturity in one year, spawning in February, but that some survived up to a maximum life span of 18 months.

Little is known about the life history of the species of Gaidropsaurus Rafinesque, 1810. Two species of this genus, G. mediterraneus (Linnaeus, 1758) and G. biscayensis (Collett, 1890) = Antonogadus megalokynodon Kolombotovic, 1894 occur in the Sea of Marmara. The egg, larvae and pelagic juveniles of G. biscayensis have never been described. Egg, prelarval and early postlarval stages attributed to G. mediterraneus have been described and illustrated by many workers, but there has been confusion in their identifications.

Three species of Gaidropsaurus, G. mediterraneus, G. biscayensis and G. vulgaris (Cloquet, 1824) are recorded from the Mediterranean. Raffaele (1888) made artificial fertilizations of eggs of Naples specimens that he identified as Motella tricirrata Nilsson, 1832 = G. vulgaris. Holt (1899) found some eggs which are similar to those described and figured by Raffaele in the plankton off Marseille, but he considered it impossible to distinguish whether the larvae which hatched out from those eggs were Motella tricirrata i.e. G. vulgaris or Motella mediterranea Lütken, 1882 i.e. G. mediterraneus. Ehrenbaum (1905–9) who re-examined the various records of eggs and larval stages of Gaidropsaurus believes that those figured by RafFaele (1888) and Holt (1899) as well as the larvae referred to Phycis Artedi, 1792 and a pleuronectid by Emery (1886) and Marion (1894) respectively probably belong to Onos (Gaidropsaurus) mediterraneus. Aboussouan (1964) who worked on ichthyoplankton of the Gulf of Marseille also attributed some eggs and larvae to G. mediterraneus and figured one of those postlarvae which is 2·65 mm in standard length.

The eggs and prelarval stage of G. mediterraneus have more precisely been described and illustrated by Soviet investigators (Vodyanitskii & Kazanova, 1954; Duka, 1958; Dekhnik, 1973)> from the Black Sea.

The recognition that non-essential metals, such as mercury, cadmium and lead, could, upon entering aquatic environments, produce harmful effects to man, directly or through food chains, has resulted in studies directed towards the identification of potentially hazardous levels.

Actinians are equipped with cnidae which function in food capture, defence and aggression (Mariscal, 1974). Cnidae cannot be renewed and after discharge they are extruded from the epithelium. Regulation of the spirocyst and nematocyst population must be important, but as yet no quantitative data about this are available for actinians (Picken & Skaer, 1966).

In his recent monograph on British Marine Amphipoda, Lincoln (1979) reported that three species of Leucothoe Leach had been recorded from the British Isles previous to his work and added a fourth species, L. richiardii Lessona. This fourth species he added after examining material collected in 1935, from the Eddystone grounds, by G. I. Crawford. The species had previously been recorded from the same area (Marine Biological Association, 1957) as ‘Leucothoe sp. nov. (allied to L. richiardii Lessona)’.

We have recently had the opportunity to examine more material of the above species from Ireland, together with Crawford's original material kindly loaned to us by Dr Lincoln. Females of this species closely resemble L. richiardii, and only the presence of males in the Irish material (unavailable to Dr Lincoln prior to the publication of his monograph), which differ significantly from those of L. richiardii, alerted us to the distinctness of this species.

Bate (1857) described a new species of Leucothoe from Banff, Scotland under the name L. procera Bate. His three line description however, is insufficiently precise to determine to which species he was referring. Later (Bate, 1862) he redescribed and figured the species under the name L. furina Savigny, and his description and figures agree well with present material except in the shape of epimeron 3 (quadrate) and the telson which is terminally narrow. Bate & Westwood (1862) again figure and describe the species under the name L. furina and re-emphasize the peculiar telson. The epimera are figured as rounded lobes. Unfortunately, Bate's type material is no longer extant, but there seems little doubt, when one considers the perfect agreement in the structure of the male gnathopod 2 between Bate's figured material and present material, that the two are conspecific.

The growing interest in farming rainbow trout in the sea (MacLeod, 1977) or in brackish water (Tatum, 1973, 1976) is economically important because it involves the use of readily available sites and resources, and provides solutions to problems related to fresh water scarcity or its increased salinity (Al-Hamed, 1971; Al-Daham & Bhatti, 1977) in certain parts of the world.

Henze (1911) was the first to discover large amounts of vanadium and sulphuric acid in the blood of certain species of tunicates. Webb (1939) established that both the sulphuric acid and the vanadium were present in blood in the same cell type, termed a vanadocyte. Since then much further work (reviewed by Goodbody, 1974) has been done on these highly unusual cells. Some species of tunicates accumulate other metals, including iron, titanium, niobium and tantalum (Carlisle, 1968) but the role(s) of these metals and indeed of vanadium itself remains unclear. The vanadium is present in vanadocytes in a reduced cationic form largely as vanadium(III) (Carlson, 1975; Tullius et al. 1980) which is complexed with a chromagen of as yet undefined structure and with sulphate as the counter anion (Bielig et al. 1966). The blood of Ascidia nigra is not capable of reversible oxygen binding (Macara, McLeod & Kustin, 1979), and there has been speculation that the reduced vanadium is involved in the synthesis of the tunic material (see Goodbody, 1974). The tunic of ascidians also contains cells rich in vanadium and sulphuric acid and roles for them in anti-fouling and anti-predation have been considered (Stoecker, 1980a, b).

The ormer, Haliotis tuberculata L. is a greatly prized species in the Channel Isles. Since the original survey of the ormer population of Guernsey and the subsequent tagging experiments (Forster, 1962, 1967), periodical short visits to the island have been made to investigate the stocks of ormers, especially in areas fished by divers; in 1968 and 1974 visits were also made to Jersey. These surveys were all made at the request of the local Sea Fisheries Committee. In this paper we seek to bring together those aspects of the results which are of scientific interest and to discuss the role of various factors which may have affected the ormer populations particularly that of changes in temperature over the last hundred years. The reproductive biology of this species has recently been reported on by Hayashi (1980).

Harpacticoid copepods (Crustacea) comprise an important taxon of the sedimentdwelling meiofauna, generally being numerically inferior to only the Nematoda (Hulings & Gray, 1971). This paper reports those species comprising the fauna of the sediments of the River Ythan estuary, particularly the intertidal sediments, and describes some of the properties of the meiobenthic copepod community structure.

Protandric hermaphroditism, the sequential change from male to female, has been reported in several superfamilies of prosobranch gastropods including the Fissurellacea, Patellacea, Calyptraeacea, and Eulimacea (Webber, 1977). It is most common in members of the Calyptraeacea and the Patellacea. In the Calyptraeacea changes in sex are readily followed by observing copulative structures (Coe, 1944). Because patellacean limpets are predominantly broadcast spawners with external fertilization, external characters that can be used to determine the sex of individuals are rare. Hence, previous to this report the occurrence of protandry in most patellacean limpets has been based primarily on sexual dimorphism in size; the smaller size classes being made up of male individuals and the larger size classes of female individuals (Willcox, 1898; Orton, 1920, 1928; Orton, Southward & Dodd, 1956; Dodd, 1956; Branch, 1974). However, given this type of data it is often difficult to assess whether the observed sexual dimorphism is indicative of protandry or merely a result of differential growth and/or survival. The presence of simultaneous hermaphrodites in the intermediate size classes, as evidence of protandry is of limited value because simultaneous hermaphrodites occur sporadically in patellaceans that do not show a sexual dimorphism in size (Dodd, 1956; Branch, 1974). The only unambiguous way of proving the existance of protandry in patellacean limpets is the direct monitoring of gonadal changes in individuals through time. We report here the first direct observations of protandric hermaphroditism in a patellacean limpet.

Lottia gigantea Sowerby, 1834 is a large (100 + mm), territorial, intertidal limpet that ranges from northern California to central Baja California, Mexico (Stimson, 1970).