Six common supra-littoral Protista from the island of Cumbrae are described and details given of their cultivation. Chlorophyceae: Nannochloris oculata n.sp., Brachiomonas submarina var. pulsifera n.var.; Cryptophyceae: Hemiselmis virescens n.sp.; Chrysophyceae: Syracosphaera elongata n.sp., Microglena arenicola n.sp., Mallomonas epithalattia n.sp.

This review provides insights into the distribution and impact of oestrogens and xeno-oestrogens in the aquatic environment and highlights some significant knowledge gaps in our understanding of endocrine disrupting chemicals. Key areas of uncertainty in the assessment of risk include the role of estuarine sediments in mediating the fate and bioavailability of environmental (xeno)oestrogens (notably their transfer to benthic organisms and estuarine food chains), together with evidence for endocrine disruption in invertebrate populations.

Emphasis is placed on using published information to interpret the behaviour and effects of a small number of ‘model compounds’ thought to contribute to oestrogenic effects in nature; namely, the natural steroid 17β-oestradiol (E2) and the synthetic hormone 17α-ethinyloestradiol (EE2), together with the alkylphenols octyl- and nonyl-phenol (OP, NP) as oestrogen mimics. Individual sections of the review are devoted to sources and concentrations of (xeno)oestrogens in waterways, sediment partitioning and persistence, bioaccumulation rates and routes, assays and biomarkers of oestrogenicity, and, finally, a synopsis of reproductive and ecological effects in aquatic species.

The classical problem of decapod egg-membrane formation and egg attachment was studied in Carcinus maenas, Homarus vulgaris, Nephrops norvegicus and Astacus pallipes. It was found that no fundamental difference existed in the membranes of the above species, and that some of the current views on the physiological processes involved were incorrect. The present study indicated that no externally deposited membranes have been formed around the egg at any stage. The outer-most membrane really consists of three layers which are histochemically distinct from one another and cannot be equated with epicuticle. The outermost layer (layer 1) of this membrane is derived from the vitslline membrane, the second layer (layer 2) is formed through solidification of a fluid exuded from the egg at spawning, and the third layer (layer 3) is formed by highly PAS-positive substance from the egg. It is suggested that the formation of this ‘trichromatic membrane’ is initiated by fertilization.

Quantitative studies of the meiofauna of marine littoral sediments have been attempted only recently. Much of the work has been done in sheltered areas such as the Danish waddens (Muus, 1967), and in estuaries (Barnett, 1968; Capstick, 1959; Rees, 1940; Riemann, 1966), or in tideless areas such as the Baltic (Fenchel & Jansson, 1966; Fenchel, Jansson & von Thun, 1967; Jansson, 1968). Beaches exposed to tides and wave action have received less attention. Renaud-Debyser (1963) studied quantitative temporal variations in the meiofauna of beaches at the Bassin d'Arcachon, France, and Island of Bimini, Bahamas. Renaud-Debyser & Salvat (1963) have compared quantitatively the meio- and macrofauna of four beaches in the English Channel and six on the Atlantic coast of France. Schmidt (1968, 1969) has analysed quantitatively the distribution and population dynamics of the meiofauna of a number of beaches on the Island of Sylt off the German North Sea coast. Recently Mclntyre (1969) has reviewed the ecology of the meiobenthos. Subsequent to Mclntyre's review, in the U.S.A. quantitative investigations of the Gastrotricha (Hummon, unpublished) and Tardigrada (Pollock, 1970) of Massachusetts beaches have been made. Tropical beach meiofauna has been studied in India (Mclntyre, 1968), on the east coast of Malaya (Renaud-Mornant & Serene, 1967) and in Tuamotu, Polynesia (Salvat & Renaud-Mornant, 1969).

One of the major advances made in the development of media for the culture of marine phytoplankton was the introduction of chelating agents as a means of controlling the concentrations of the trace metals necessary for plant growth; an excellent historical survey of this field has been provided by Provasoli, McLaughlin and Droop (1957). Much of the discussion concerning the role of the chelating agents has centred upon the maintenance of the iron in solution at concentrations adequate for plant nutrition (Droop, 1961; Provasoli, 1963; Johnston, 1964). In the absence of chelators, the pH of the culture media would result in almost complete precipitation of the iron.

INTRODUCTION.

1. A series of hauls with the ring-trawl were made at five depths in water 50 metres deep, so that samples were obtained approximately in daylight, at dusk, at midnight, at dawn, and again in daylight.

A depth-recorder was used with the net giving a graphic record of its path through the water.

2. Examination of the catches demonstrated the diurnal changes in vertical distribution of the species caught by the ring-trawl.

3. Four types of behaviour were shown:—

(a) A definite migration to the surface in the dark hours of certain forms living in the deeper layers in the daytime.

(b) An expanding of the distribution of other organisms, that in the daytime had a zone of maximum abundance in the deeper layers, so that they were evenly scattered from the surface downwards.

(c) Certain animals showed no or very little change in their vertical distribution during the dark hours.

(d) A movement up to the midwater region by those forms that during the daytime adopt either a truly benthic existence or are congregated in the water layers immediately adjacent to the sea floor.

(Lists of species grouped under their respective types of behaviour are to be found on page 780.)

4. Many such observations are required before conclusions can be drawn as to the normal diurnal behaviour of plankton animals: this is a definite record of what occurred in this locality in mid-July at a period of full moon in fair weather.

Luminescence is very common among marine animals, and many species possess highly developed photophores or light-emitting organs. It is probable, therefore, that luminescence plays an important part in the economy of their lives. A few determinations of the spectral composition and intensity of light emitted by marine animals are available (Coblentz & Hughes, 1926; Eymers & van Schouwenburg, 1937; Clarke & Backus, 1956; Kampa & Boden, 1957; Nicol, 1957b, c, 1958a, b). More data of this kind are desirable in order to estimate the visual efficiency of luminescence, distances at which luminescence can be perceived, the contribution it makes to general back-ground illumination, etc. With such information it should be possible to discuss more profitably such biological problems as the role of luminescence in intraspecific signalling, sex recognition, swarming, and attraction or repulsion between species. As a contribution to this field I have measured the intensities of light emitted by some pelagic species of animals.

The results of experiments recorded by Bayne & Scullard (1977) confirmed earlier studies (Bayne, 1973) in describing a decline in the rate of oxygen uptake (Vo2) by Mytilus edulis during starvation, eventually reaching a steady-state value, called the standard rate of oxygen consumption. Earlier experiments had also shown that if such starved mussels were fed, oxygen uptake increased rapidly to a high level called the active rate of oxygen consumption (Thompson & Bayne, 1972; Bayne, Thompson & Widdows, 1973). Some of this increase in metabolic rate is undoubtedly due to an increased filtration rate that is stimulated by the presence of food (the ‘mechanical cost of feeding’ discussed by Bayne et al. 1976), and part is due to the ‘physiological costs of feeding’, which includes energy utilized in digestion and assimilation of the food, and energy that is lost during deamination and other catabolic processes that accompany digestion (Warren & Davis, 1967). Increases in metabolic rate associated with feeding have been called the specific dynamic action (SDA) of the ration (see Harper, 1971, for a discussion) or the apparent SDA (Beamish, 1974)5 and they have been related to aspects of protein metabolism (Krebs, 1964). This paper describes the results of some experiments designed to examine the relationships between SDA and ammonia excretion in Mytilus edulis L.

The sense organ of Carcinus mamas located in the joint between the dactylo- and propodite possesses several types of sense cells (Wiersma & Boettiger, 1958). The most interesting types react to unidirectional displacement of the dactylopodite with equal sensitivity over the total possible arc of movement. Velocity has little influence on the discharges of the movement fibres since the maximum rate of firing is reached at a speed which is relatively little faster than the threshold. Fibres with marked differences in threshold are present for both extension and flexion. Other units in the organ react like conventional stretch receptors and give continuous discharges as long as the joint is near one of the extreme positions. Again different units are present for extension and for flexion. These position fibres are on the whole smaller than the movement fibres and their cell bodies have a more peripheral location in the organ.

The nature of iron occurring in sea water, and its utilization by diatoms, is discussed.

Diatoms in the sea obtain many thousand times more iron than calculation shows they can obtain by diffusion of iron ions from the surrounding water.

Evidence is presented that ferric hydroxide is readily adsorbed on the surface of diatoms.

It is shown that colloidal and larger particles of ferric hydroxide or phosphate can be utilized by, and support the growth of diatoms.

Experiments show that the diatoms Nitzschia closterium and Lauderia borealis require, for continued growth, a very small quantity of iron compared with that found on, and in, diatoms taken from the open sea.

It is contended that iron hydroxide adsorbed on diatoms is in contact with an interface where its solution, and subsequent passage into the cell, is probable.

On the flat shore at Whitstable the population of common winkles is distributed appreciably at random over a variety of substrata ranging from wooden groynes, through shingle to muddy sand, between tidal levels corresponding to H.W.N.-E.L.W.S. but with a maximum density near M.T.L., although aggregations tend to occur in wetter situations and where planking joins vertical groyne posts.

Observations on winkles marked with a dab of paint of distinctive colour show that they tend to remain in approximately the same position for many weeks.

For most of each tidal period winkles remain settled in situations such as stones or groynes, which provide good holding ground, but as the tide recedes or the incoming tide reaches them, they become activated to crawl, feeding meanwhile. These feeding migrations are recorded in the sand by roughly U-shaped tracks and can be seen under favourable circumstances as similar tracks in the vertical plane for winkles on groynes. By such excursions the animals are enabled to move, feed and return to approximately the place from which they started and this serves to explain how they maintain their station on the shore.

When settled on vertical surfaces, winkles always orientate with the head uppermost, when the foot may be withdrawn and the animal become attached by a film of dried mucus.

When crawling the eyes are exposed and the tentacles bend to test the substratum, but only that part of the tentacle distal to the eye bends so that the optical axis of the eye maintains a constant angle to the body axis.

The work described in this paper is a contribution to the general problems of rearing the larvae, and growing the spat of the European flat oyster, Ostrea edulis L.

The specific aspect of the problem dealt with in detail is the place taken by minute motile organisms (naked dinoflagellates and other unicellular algae) in the food requirements of the developing veliger larvae.

Six such flagellate organisms, ranging in size from 1·5 to 7 μ in diameter, have been isolated from sea water, and are maintained in pure culture, under conditions described. Pending specific identification, these are denoted by letter-labels only. These organisms have been used, over a period of years, in feeding experiments with oyster larvae.

Thin-layer chromatographic procedures using silica gel and glucose have been employed for the examination of the pigments of twenty-three species of marine phytoplankton, drawn from a number of classes. Several new xanthophylls have been found including one similar to fucoxanthin which is the principal pigment in an, as yet, undescribed member of the Haptophyceae. The pigment array of a species of Olisthodiscus sp. (Plymouth no. 239) differs considerably from that of members of the Xanthophyceae and this species is probably incorrectly classified.

Many of the difficultics found in naming and classifying Crustacea are due to the extraordinary modifications caused by growth and sex, and the confusion arising from our lack of knowledge of these developmental stages has led to many errors.

Three species of grey mullet have been recognized in the English fauna, namely, Thick-lipped, Thin-lipped, and Golden. There have been several revisions of the Mugilidae, and the names preferred here are: Thick-lipped grey mullet, Crenimugil labrosus (Risso); Thin-lipped grey mullet, Liza ramada (Risso); Golden grey mullet, Liza aurata (Risso).

In spite of the controversy surrounding the accidental introduction of the Japanese seaweed Sargassutn muticum (Yendo) Fensholt onto two continents, the startling south-ward expansion of its range on the Pacific coast of North America (Norton, 1977 a), and the failure of an eradication campaign on the south coast of England, surprisingly little is known about the ecology of this species. Work has recently begun in both southern California and Britain (Nicholson et al. 1977; Lewey & Farnham, 1977). Unfortunately the ecological studies in Britain have been hampered by the conflicting aims of trying to study the plant and at the same time trying to eradicate it.

Benthic faunal communities have usually been described from data collected during a single survey, and it has been assumed that most benthic communities are reasonably stable. However, in areas such as important fishing grounds or around effluent disposal areas where surveys have been repeated periodically, the results quite frequently show marked changes. These do not always correlate to annual breeding cycles but are more unpredictable and of a different period.

1. A method of estimating nitrates in sea-water is described.

2. A considerable concentration of nitrates occurs in the depths of the ocean and a very low concentration (0 to 10 parts per 1000 million of nitrate-nitrogen) in the surface layers of those areas where there is no upwelling of water from below.

3. The nitrates in the water of the English Channel, twenty-two miles south-west of Plymouth, are almost entirely utilised by phytoplankton in the summer, and commence to be reformed from ammonium salts at a greater rate than they are utilised by the end of the summer.

The question of how organisms living below 1000 metres depth in the oceans obtain food in sufficient quantity to survive has lately received a lot of attention (Vinogradov, 1968; Sanders & Hessler, 1969; Fournier, 1972). The oldest and simplest theory, first advocated by Agassiz (1888), is that deep-sea organisms are nourished by a ‘rain’ of organic detritus from overlying surface waters. Detritus is defined to include all organic particles, living and dead, which sink passively. An alternate proposal by Riley (1951), Vinogradov (1962) and Wickstead (1962) is that the main supply of food for deep-sea plankton is conveyed from the euphotic zone by overlapping vertical migratory plankters.

Thorson (1946) considered in detail the earlier views of Appellöf (1912), Orton (1920) and Runnström (1928) that breeding activities of the majority of marine organisms were controlled by the temperature of the sea and referred to this as Orton's rule. RecentlyCrisp (1954) and Qasim (1956) also reviewed the existing literature on this subject in relation to barnacles and fish. By considering the seasonal availability of planktonic food in con-junction with Orton's rule, they explained why tropical species inhabiting cool temperate waters have a breeding season confined to the warmer months, whereas boreo-arctic species throughout their whole range breed only during colder months.