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.

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.

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.

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.).

Introduction

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

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.

Introduction

The diatom Phaeodactylum tricornutum Bohlin has been used in numerous experiments on the physiology and biochemistry of diatoms since the publication of the first paper involving this organism by Allen & Nelson (1910). The taxonomic position of the organism has been dealt with by Lewin (1958), who also lists the papers which she considers to have involved the use of P. tricornutum. The present study reports the results obtained from a comparison of different isolates of this organism.

The subumbrella of the hydrozoan medusa Obelia consists of three layers of cells. The innermost layer is the endodermal lamella whose broad polygonal cells are in close contact with the middle layer of polygonal myocytes which have striated myofibrils running in two layers at right angles to one another in the same cell. These myofibrils extend beyond the myocytes as plasma membrane-enclosed prongs to make contact with the prongs of neighbouring cells in such a way that whole mounts give the impression that the slender myofibrils are continuous over the subumbrella. Cross-layered myocytes can be seen to be another means of decreasing the surface area of the subumbrella, a condition necessary for medusoid locomotion. Helically banded radial myofibrils are found in the outer layer.

57Co-labelled vitamin B12 was used to study the kinetics of vitamin B12 limitation in Monochrysis lutheri in continuous and exponentially growing batch cultures and in washed cell suspensions.

Specific growth rate in the chemostats was found not to depend directly on medium substrate concentration but on the concentration within the cells (cell quota), obeying a hyperbolic equation of the form

The earlier investigations (Raymont, Austin & Linford, 1964, 1966) on the brackish-water, semi-planktonic mysid, Neomysis integer (Leach), dealt with the total protein, lipid and carbohydrate fractions, together with chitin and ash. Results showed that a relatively high protein content (mean 71 % dry weight) was typical of Neomysis; the protein showed very little change throughout the year. Lipid was much lower and more variable (7–15%; mean 13 % dry weight), and carbohydrate was especially low (mean 2.5 % dry weight). Ash and chitin together amounted to some 14 % dry weight (Raymont et al., 1966).

Campecopea hirsuta (Montagu) occurs in rock crevices, and among barnacles and the lichen Lichina in south-west Britain. It is particularly abundant on shores ex-posed to wave action, occurring most commonly at about M.T.L. and below on shallow slopes, and from M.T.L. to H.W.N. on steep slopes. Young Campecopea of about 1–5 mm long are released in late summer. Females attain a maximum length of 35 mm and males 4–0 mm, each having a life span of no more than 1½ years.

Experiments have been made to elucidate the problem of hyperosmotic regulation in the mud-dwelling euryhaline amphipod, Corophium volutator. The animal produced urine hypo-osmotic to the blood when acclimatized to low salinities, and isosmotic urine at salinities above 20%. The restricted permeable areas of the cuticle have been localized by silver staining. Over a range of salinities from 1 to 35 % C. volutator was found to maintain Na+, K-−, Ca2+, Cl-−, more concentrated than the medium, and Mg2~ less concentrated. The importance of these mechanisms in assisting hyperosmotic regulation is discussed.

The Preliminary Check-list of British Marine Algae (Parke, 1953), with three subsequent lists of additions and corrections (Parke, 1956, 1957, 1959), was superseded by the Revised Check-list of British Marine Algae (Parke & Dixon, 1964). Since the publication of the latter, changes, both taxonomic and systematic, have been sufficiently numerous to warrant the present list incorporating additions, corrections and emendations.

The authors take full responsibility for all the changes from the 1964 Check-list. The responsibility for the preparation of the lists of species for each Class in the 1964 Check-list was as follows: (1) Cyanophyceae, H. T. Powell; (2) Rhodophyceae, P. S. Dixon; (3) Cryptophyceae, M. Parke; (4) Dinophyceae, D. Ballantine & M. Parke; (5) Haptophyceae, M. Parke; (6) Chrysophyceae, M. Parke; (7) Craspedophyceae, M. Parke; (8) Xanthophyceae, M. Parke; (9) Phaeophyceae, H. Bladder, G. Russell, P. S. Dixon & M. Parke; (10) Prasinophyceae, M. Parke; (11) Chlorophyceae, E. M. Burrows, P. S. Dixon & M. Parke.

The sequences of classes is as in the 1964 Check-list and there have been no changes in the geographical limits used therein (the coasts of Britain and Ireland or in adjacent waters, i.e. the sea area bounded by 47° N. and 63° N., 11° E. and 30° W.). Three classes (Bacillariophyceae, Rhaphidophyceae, Euglenophyceae) are still not represented and the authors would be grateful for records of marine species of these in order to facilitate their inclusion at some time in the future.

The compilers welcome any comments on the Revised Check-list (1964) or the present list.