The entire cell surface, including the flagellar surfaces, of three species of Pyramimonas and of two different strains of Pyramimonas-hke zooids of Halosphaera are shown to be covered with scales in at least two layers, namely, an underlayer of very small scales arranged directly on the flagella membrane or plasmalemma and one or more outer layers of much larger scales of different character. On one and the same cell the shapes of the scales of all layers are different on the flagella from those on the body. Among all the taxa studied the flagella scales are very similar but those of the bodies are specifically differentiated; details are illustrated in the plates. In two taxa {Halosphaera and Pyramimonas amylifera) the outer scales on the flagella have been shown to be consistently arranged in 9 longitudinal rows; numerical information is not available for the other taxa studied but they are not expected to be different. The presence of an unusual type of flagellar hair has also been noted though those have not yet been studied in detail.

Last year preliminary results on the feeding of some of the commoner plankton organisms were published (1922). Further progress is made this year, more especially on the living animals, chiefly cœlenterates, kept in the plunger jars. The results of these experiments, specially undertaken to find out whether medusæ naturally caught and ate small fishes, answer the question undoubtedly in the affirmative. A large number of the smaller medusæ were kept alive, and most of these were seen to catch and eat fishes. The usual method of catching the food is with the outstretched tentacles, which, drawn out to very fine threads, react when anything living touches them, stinging the prey with their stinging cells; the tentacles then contract and helped by others, and often also by the lips and sides of the umbrella, manage to convey the food to the mouth, from which it reaches the stomach and is digested. A certain amount of selection is apparent, for the tentacles often reject food. Moreover, medusæ of one species do not as a rule eat one another, although taking other species voraciously. If many small fishes are available the smaller crustacea are neglected by many of the medusæ, although these may be taken when other food is searce. Sagitta bipunctata and Tomopteris helgolandiea are popular with nearly all those that can eat fishes. Certain medusæ, e.g. Sarsia tubulosa and S. prolifera, have never been seen to eat anything but crustacea (copepods or decapod larvæ), and fishes have not been seen inside them.

During the course of earlier work with larvae of Ophelia bicornis Savigny it became increasingly clear that a major factor in stimulating these larvae to settle and metamorphose is the presence, on sand grains of suitable size, of living micro-organisms such as bacteria, in numbers neither too many nor too few (Wilson, 1954). It had been shown that an acid-cleaned sand (which is neutral or almost so) kept in sea water becomes increasingly attractive to these larvae with time. It had been admitted, however (loc. cit., p. 366), that these results were derived from a comparison of experiments not designed to this end, and that further tests, planned for the purpose, were desirable.

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 Blue Gym Initiative was created in the UK in 2009 to explore: (1) whether blue space environments might be positively related to human health and well-being; and (2) whether the public could be encouraged to preserve and protect these environments. Whilst the wider initiative considers all blue spaces including inland bodies of water (e.g. lakes, rivers and canals as well as the coasts and oceans), to date the focus has been primarily on marine and coastal environments. In this paper, we provide a brief history of the Blue Gym Initiative, and outline some of the research that has emerged to date. An important early finding was the observation that individuals living near the coast are generally healthier and happier than those living inland; much subsequent work has tried to understand why this might be. More recently we have begun to focus on how to promote pro-marine behaviours (e.g. sustainable fish choice, reduction of plastic use, avoidance of littering). This strand is still very much work in progress but highlights the importance of understanding public awareness, values and attitudes and the power of visualization in communicating the marine sustainability issues. We conclude with a brief discussion of some of the implications of the findings and future research needs.

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.

Eggs of plaice, Pleuronectes platessa L., were incubated in salinities of 5, 17.5, 35 and 50%. After fertilization a large concentration difference is maintained between the yolk and the external medium; this difference is present throughout development. The unfertilized egg becomes isosmotic with the medium within 24 h.

High mortalities were found at all stages of development in salinities below 17.5% most eggs died in the blastula or early gastrula stages. In addition, mechanical disturbance (e.g. during transport) also led to many deaths at this stage.

Water movement could occur between the environment and both the yolk and embryonic cells, it was detected by changes in the freezing-point of the yolk and changes in the volume of the blastula cells.

After hatching, the yolk-sac larvae tolerated salinities of 15–60% for 1 week, and the body fluid concentration was regulated within fairly narrow limits in these salinities. After metamorphosis, tolerance to high salinities was less (45% for 1 week), but tolerance and regulation in low salinities was greater (2.5% for 1 week). It is suggested that functional changes in the epidermis and kidney underlie these changes in tolerance.

Introduction

An investigation of the effects of salinity on the early development of the herring (Holliday & Jones, 1965) suggested that the ability to osmoregulate was present in the cells of the early blastula, but not in the vitelline membrane of the fertilized egg. The yolk was not fully regulated until gastrulation was complete; until this time it was approximately isosmotic with the medium in which it was being incubated.

Microbial films represent the site at which grazers exert their influence upon the recruitment of settling macroalgae and animals. The overall purpose of this study of seasonal and spatial variation in abundance and composition of epilithic microbial films was to relate such patterns to macrobenthic community dynamics within the Fucus-bar- nacle mosaic characteristic of moderately exposed rocky shores on the Isle of Man. Additionally selective grazing in Patella vulgata was examined by comparing dietary and epilithic microalgal assemblages and how this varied seasonally and spatially within the mosaic. Chlorophyll analysis was used as an index of microalgal standing crop while SEM allowed in situ estimation of microalgal abundance.

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.

The organization, cellular composition and function of the digestive diverticula has been described for a large number of molluscs (Nakazima, 1956; Owen, 1966; Purchon, 1968). Changes in the digestive cells which are associated with intracellular digestion have also been widely recognized (Graham, 1938; Carriker, 1946; J. E. Morton, 1955, 1956, 1959; Owen, 1955, 1966, 1970, 1972; Sumner, 1965, 1966a, b, 1969; Morse, 1968; McQuiston, 1969; Walker, 1970; Merdsey & Farley, 1973). In general the digestive cells show three cyclic phases, (1) absorption, (2) digestion, (3) fragmentation and excretion, and these phases, with only minor modifications, are typical of most molluscs (Owen, 1966). In many groups, especially gastropods, the changes in the digestive cells within the tubules of the digestive diverticula often appear to be synchronized and consequently the tubules have a uniform appearance throughout the diverticula. In the Bivalvia, however, this type of synchrony has not generally been recognized. Since bivalves have been considered to feed more or less continuously (Purchon, 1971; Winter, 1973) it is not surprising that a homogenous appearance was only exceptionally observed, e.g. J. E. Morton (1956), J. E. Morton, Boney & Corner (1957).

Globigerinoides sacculifer (Brady), a common planktonic foraminifer collected by SCUBA off Barbados, was maintained under six feeding regimes at constant light and temperature conditions. Five groups of 63 specimens each were fed 1-day-old Anemia at the rate of one nauplius per specimen every 1, 2, 3, 4 or 7 days. A starved control group received no Anemia. The rate of chamber formation and shell size increased proportional to the feeding frequency. However, an inverse correlation existed between survival time and feeding frequency. Normally, survival time ends with gametogenesis which terminates the life of the mother cell. Organisms fed more frequently reached maturity and underwent gametogenesis more rapidly than those fed less frequently. The average survival time of G. sacculifer in culture ranged from 7 days for the daily-fed group to 11 days for the group fed every 7 days. While the latter grew more slowly they eventually reached maturity. Starved individuals rarely formed chambers and often died without undergoing gametogenesis. Symbiotic zooxanthellae presumably prolonged survival of starved organisms. Extrapolation of survival data suggests G. sacculifer has a variable life span of 2 to 4 weeks depending on food availability.

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).

The impact of bottom trawling on cold-water corals (CWC) has been thoroughly studied and shown to be long-lasting; however the effects of bottom longlining on CWC ecosystems have received little attention. The present paper identifies the principal CWC species landed by bottom longlining in Faial (Azores) from 150 to 600 m depth. Data were obtained from a survey of 297 landings during four months coupled with 16 interviews with fishermen. A distinction was made among corals brought on deck directly entangled in the fishing gear (primary by-catch) from corals brought up associated with other larger CWC species or rocks (secondary by-catch). Forty-five (15.2%) of 297 fishing trips surveyed landed coral specimens. The survey recorded 39 different CWC taxa in the by-catch, belonging to five different orders (Scleractinia, Alcyonacea, Antipatharia, Zoanthidea and Anthoathecata). Secondary by-catch included a larger number of species but the total number of corals was in the same order of magnitude for both groups. The taxa most frequently encountered were Leiopathes spp., Errina dabneyiand Dendrophyllia sp. CWC taxa in the by-catch were mostly medium size (10–60 cm), 3-dimensional and branched colonies. Local ecological knowledge of fishermen confirmed that the corals recorded were representative of their past experience and also revealed a general agreement that there has been a decrease of CWC by-catch on traditional fishing grounds. Corals are common by-catch in bottom longline fisheries around the Azores and so conservation measures may be required.

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.

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.

Metazoan meiofauna were studied in replicated multiple-corer samples obtained at a bathyal site (1320–1360 m depth) in the Porcupine Seabight (51°36′N 13°00′W) before (April) and after (July) the delivery to the seafloor of a phytodetrital pulse originating from the 1982 spring bloom. In all samples the metazoan meiofauna was dominated by nematodes; harpacticoid copepods and their nauplii were the second most abundant taxon. Population densities and biomass were very similar in both sample sets, the only significant differences being in the numbers of ostracods (higher in April) and nauplii (higher in July). Furthermore, vertical distribution patterns in the top 5 cm of sediment indicate that the meiofauna did not migrate towards the sediment surface following the phytodetrital pulse. The lack of a metazoan meiofaunal response contrasts with published evidence, based on the same samples, for a substantial increase in the foraminiferal abundance following the sedimentation event. Thus our results suggest that metazoans (as a whole) fail to exploit and utilize phytodetritus as rapidly as foraminifera. This probably reflects the energetic expense of egg production coupled with frequently slower rates of somatic growth among metazoans. In addition, foraminifera may outcompete metazoans for detrital food because they possess extremely efficient food-gathering organelles (granuloreticulate pseudopodia) and are able to raise their levels of metabolic activity very rapidly. However, metazoan responses at the species level, or over longer time periods (>3 months), would not have been detected and so remain a possibility.

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.

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.

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.