Gold has been determined in six marine sponges by neutron activation analysis. The amounts found (1·8–12·6 × 10−8 g/g dry sponge) are higher than would be expected from measurements of the distribution of 198Au between sea-water and dead sponge samples.

Many attempts have been made to devise methods for concentrating gold from sea water, but none of them are commercially viable. Recent work has shown that gold can be concentrated by adsorption or absorption on certain artificial polymers (Hummel, 1957; Bowen, unpublished). This note describes some measurements of the accumulation of gold by marine sponges whose scleroprotein structure resembles some of the artificial polymers employed.

An investigation into the histochemistry and ultrastructure of the digestive gland of Elysia viridis has revealed the presence of two types of epithelial cells, one of which contains numerous, structurally intact algal chloroplasts. Chromatographic studies indicate that these chloroplasts are derived from the animal's specific food, the alga Codium tomentosum. Following ingestion by the animal these do not appear to be digested or excreted, but accumulate and are maintained in the digestive cells. Autoradiographic studies suggest that they may be of some benefit to the animal as symbiotic organelles. Such a phenomenon may prove to be widespread among related species of Opisthobranchia.

Introduction

The importance of temperature in limiting the distribution of marine invertebrates by its effects on breeding and survival has been shown by Orton (1920) and Hutchins (1947). Prosser (1955) recognized the use of physiological variation in describing interspecific relations, intraspecific variation and the limits of ecological range. The effects of temperature on marine organisms have been reviewed by Kinne (1963). Temperature responses are to a certain extent genetically fixed and species characteristic, although it is well known that many species can adjust these responses with changing temperatures.

The use of natural plankton and other foods, and of transfer techniques during phases of mortality before metamorphosis, has made it possible for substantial numbers of herring larvae to be reared beyond this stage, thus supplying requirements for experimental work. A survival to and beyond metamorphosis of over 10% of larvae passing the yolk-sac stage (3–4% of hatched larvae) has been obtained.

An attempt is made to explain the great variations in gross shell morphology noted in field populations of Mytilus edulis.

In any one mussel population, variation in shell form can be attributed to differences in age, old mussels having proportionately heavier shells where width often exceeds shell height. This is invariably accompanied by down-turned, divergent umbones and varying degrees of incurvature of the ventral shell margin.

Variations in the age structure of mussel populations from different habitats can also account for local variability in shell morphology. Localities where the life expectancy of mussels is increased due to absence of predators (especially in the upper shore) reveal a high incidence of old ‘ungulate’ individuals, whereas populations in which the mussel turnover is more rapid show a preponderance of relatively young mussels.

Shell morphology is greatly influenced by growth rate and density. These probably exert their effect through physical compression which is maximum in localities of fast growth and high density and least in areas of slow growth and low density. High compression leads to an elongate form whereas low compression results in higher, more triangular shaped shells. Growth rates and densities, even within the same habitat, are, however, exceedingly variable.

Since all environmental conditions vary in both time and space, wide variation in shell morphology is to be expected, even in animals from the same locality.

Transplantation experiments indicate that variation in shell morphology is essentially phenotypic, older animals being more likely to exhibit a form which is characteristic of their particular habitat. Smaller mussels from widely different habitats show remarkable similarity in shell morphology.

Off the coasts of the Eastern Aegean Island of Chios underwater observations were made on the labrid Crenilabrus (= Symphodus) ntelanocercus (Risso).

It was found that undisturbed observation could be made from 4 to 5 m away from the fish's territory, but if closer, then diver-orientated behaviour occurred. The fish might inspect the diver, or if alarmed, show fright reactions of different intensities. Conflict situations for the fish sometimes resulted in displacement chaffing. Pursuit caused the fish to show a series of escape reactions depending upon the intensity and persistence of the pursuit. Initially the fish showed avoidance reactions by fleeing or following set ‘escape routes’; further pursuit caused it to hide among the eel-grass, Posidonia; and finally aggregation and flight were resorted to.

The oil-spill removers BP 1002, Gamlen, Slipclean and Dasic have been tested for toxicity using the barnacle Elminius modestus Darwin. All four substances were more toxic than the laboratory detergent Teepol-L, and Kuwait crude oil. BP 1002 was the most toxic of the oil-spill removers, and Dasic the least, but all were poisonous at concentrations between 2 and 10 ppm.

The iron nutrition of Phaeodactylum tricornutum (Bohlin) has been studied, and the limitation of growth because of iron deficiency demonstrated. Evidence is presented suggesting the ability of the organism to utilize paniculate iron and to adjust its utilization of iron in the presence of a continuing deficiency. One effect of lack of iron is a reduction in the degree of pigmentation and the ability of added iron to restore the pigmentation. Figures are presented showing the iron content per cell, and a comparison with other organisms suggests that the brackishwater P. tricornutum may be atypical when compared with coastal and oceanic members of the marine phytoplankton.

During April-June, 1967, tow-netting for bass eggs was carried out at four places on the Irish coast. Small numbers of bass eggs were obtained at two of these places, namely the Splaugh Rock, near Greenore Point, Co. Wexford and Youghal Harbour, Co. Cork. They were taken near the surface, in water of the salinity range 30–34.5%, and of surface temperature range 10.5–13.2°C.

The Irish material was larger than described by Bertolini (1933) from the Mediterranean, but smaller than described by Jackman (1954), who hatched eggs spawned in the Plymouth Laboratory Aquarium and described the larvae.

Introduction

Bass have spawned in the aquarium at Naples, and their eggs have been found in plankton in the Mediterranean (Raffaele, 1888; Bertolini, 1933). Bass have also spawned in the aquarium at Plymouth, and their eggs and the resulting young stages have been described by Jackman (1954).

Hitherto, however, the eggs of bass do not appear to have been found on the coasts of Britain or Ireland. The only young stages recorded were 14 post-larvae from 4 to 7.5 mm long, taken in the Eddystone area in the years 1925, 1926, 1931 and 1933, with dates of capture between 17 March and 4 June (Russell, 1935).

As part of a programme of research on the biology of bass in Irish waters, tow-netting was carried out in 1967 at the Splaugh Rock off the Wexford coast; at Dungarvan, Co. Waterford; at Youghal, Co. Cork; and at Baltimore, Co. Cork (Fig. 1). The Splaugh, Dungarvan and Youghal are places where bass ‘shoal’; that is, frequently gather in shoals to attack sand-eels, herring fry or sprats at the surface.

Concentrations of zinc and copper have been measured in 18 species of decapod crustaceans, ranging from freshwater to purely marine species. Although the intake of zinc and copper probably varies considerably, the majority of animals contain between 20 and 35 μg/g of both metals. This is probably because the concentrations in the body fluids and tissues are regulated. Reasons for differences between the concentrations of zinc and copper in the individual tissues of different species are discussed and the ways in which regulation is achieved are compared.

Rates of respiration and nitrogen excretion have been measured for freshly caught Calanus finmarchicus (Gunnerus), Calanus hyperboreus (Krayer), Metridia longa (Lubbock) and Pareuchaeta norvegica (Boeck), from the Gulf of Maine at all seasons. The dry weight, total (Kjeldahl) nitrogen, and fat were also determined for the same animals. Seasonal variation in weight-corrected respiration and nitrogen excretion followed a similar pattern for all four species, being high in the spring and decreasing gradually through summer and fall to a winter minimum. However, the relative proportions of oxygen utilized to nitrogen excreted were different from season to season for each species. In Calanus spp., O: N ratios by atoms were highest in May, immediately after the spring bloom of phytoplankton, when the animals were rich in fat. With C. hyperboreus the ratio then declined gradually through summer and fall to a low point just before the spring bloom (March and April) when populations contained the least amount of fat; but with C. finmarchicus the ratio fell much more rapidly, remaining near 17 through summer and fall and increasing again with the production of the overwintering generation. In Metridia and Pareuchaeta the O:N ratios did not show as much seasonal variation, although there was a pronounced increase for Metridia just after the spring bloom. Both species usually had higher respiration and excretion rates and lower O:N ratios compared with Calanus spp.

Introduction

During the last fortnight in September of 1965, 1966 and 1967 littoral species of Spirorbis were collected by the author and, during the early part of April 1966, sublittoral species were collected by the British Museum (Natural History) and University of London Sub-Aqua Expedition. Ten species, including one new to the British Isles and two new to science, were found to be present. Details of their occurrence, together with the descriptions of the new species, are contained in this report. Representative series of the material collected are deposited in the British Museum (Natural History). In this account, specimens collected by the author are indicated by (T.H.) and those collected by the Sub-Aqua Expedition by (S-Aq. Ex.).

Suspensions of heart-body tissue and of coelomocytes in solutions of porphobilinogen produced uroporphyrin. This affords additional evidence for the haematopoietic function of the heart-body, and for the view that the free porphyrins found there and in the haemoglobin-containing coelomocytes are formed by these tissues' own activity in haem synthesis.

Various enzymes have been successfully localized in whole specimens of several groups of marine animals up to 5 mm body thickness. With certain exceptions the animals are fixed for a short time and then incubated in media modified from those designed for sections. After incubation the specimens are stored in fixative or buffer for later serial sectioning back at the laboratory.

Introduction

The first naturally occurring compound to be identified containing a carbon-phosphorus bond was 2-aminoethyphosphonic acid

A well-marked seasonal cycle in the total calcium content of the plasma was shown to occur in adult cod, Gadus morhua L., of both sexes: these changes were not found in juvenile, immature cod. The changes in concentration of plasma total calcium appeared to be associated with gonadal maturation, the period of hypercalcaemia coinciding with the maturation cycle and the plasma calcium falling to a resting level again after spawning. Seasonal changes were greatest in the female cod and it is suggested that the raised level of calcium is associated with vitellogenesis in the ripening ovary, probably under the influence of oestrogens. The cycle in the male is not yet fully understood.

Three hundred and thirty-one turbot and 350 brill of varying ages were examined for infection with the tapeworm Bothriocephalus scorpii (Müller, 1776).

This survey showed that: (i) turbot and brill acquired infections of B. scorpii before they were 1 year old; (ii) all the adult turbot were infected with B. scorpii, often heavily, whereas only half the adult brill were infected and then only slightly; (iii) differences in the structure of the gut mucosa could account for the strong attachment of the scoleces in turbot compared with the loose attachment in brill.

A review of the literature indicated a lack of quantitative data on cell division in macroscopic algae in the laboratory and particularly in situ. By means of SCUBA techniques selected red algae were collected from their in situ location on a 24 h basis through the seasons of the year. The varied oceanographic and meteoro-logical conditions on the southern tip of Vancouver Island provided shore habitats of adequate contrast. Rhodomela larix was found to be a suitable test species for quantitative work, and differentials in mitotic activity in the growing parts of this plant were explored. Using squash techniques a method of quantitative estimation of mitotic activity employing a point-counting method was developed. It was found necessary to define the limits of mitotic phases in R. larix to facilitate quantitative analysis which was carried out over 24 h periods both in July and in February. Mitotic activity in R. larix showed a well-marked periodicity, although only the July data are statistically significant. The distribution of mitotic activity throughout the day was similar both in July and in February despite the dissimilarity of photo-period, temperature and tidal factors, which suggests the presence of a circadian rhythm. This preliminary work is being continued by further in situ investigations correlated with laboratory cultures under controlled environmental conditions.

Introduction

Despite the amount of literature published concerning the entocommensal rhynchocoelan, Malacobdella grossa (O. F. Müller), few references have been made about its ecology and life-history, and these for the most part consist of little more than isolated observations. The ecological knowledge available is composed almost exclusively of details pertaining to geographic distribution, hosts from which the worm has been recorded, and reports of the infection incidences found. Apart from suggestions by von Kennel (1878) and Gering (1911) that a relationship exists between host size and both worm incidence and size, the only detailed analysis of the host-commensal associations is that of Gibson (1967), who established a statistical correlation between host size and both incidence of infection and nemertean length, recorded the disposition frequency of the worm within its host, and examined both the occurrence of multiple infections and the Malacobdella population size composition.

Von Kennel (1878) further suggested that host-commensal size relationships would depand on the age (i.e. size) at which infection by the pelagic larvae occurred, and Ropes (1963) speculated on the role played by surface currents upon larval distribution.

Cod (Gadus morhua L.) from the Arcto-Norwegian stock were caught during their gonadal maturation cycle, and plasma samples from individual fish obtained for the determination of total calcium and vitamin A aldehyde (retinal + dehydroretinal). The concentrations of these two substances in the plasma of female cod caught during January–March were significantly correlated r = 0·728, P < 0·001, and this result supports the hypothesis that the increases in concentrations of plasma calcium and vitamin A aldehyde during the period of ovarian maturation may be controlled by the same mechanism. In September, just prior to ovarian maturation, and in October, at the beginning of maturation, there was no correlation between the concentrations of the two substances.