Seven postlarvae and one juvenile of the golden mullet and two postlarvae of the thicklipped mullet, ranging from 60 to 27 mm and from 14-88 to 21-44 mm in length respectively, were found in plankton collections taken in the Plymouth area on 10 October and 14 November 1969. The morphological characters of these specimens are described and illustrated, and the presumptive spawning periods of the two species are briefly discussed in this paper.

INTRODUCTION

It is well known that littoral teleosts, such as Blennius pholis, are on occasions subjected to considerable and abrupt variations in the salinity of their environment. Smith (1930) constructed a tentative model of the processes involved in the osmoregulation of teleosts; quantification of the various components of the Smith model has been extensive, but little attention has been paid to the respiratory stresses undergone by teleosts in fluctuating salinities.

INTRODUCTION

The occurrence of dense beds of the brittle-star Ophiothrix fragilis (Abildgaard) in certain localized areas around the British Isles has been reported by several authors (Allen, 1899; Vevers, 1952; Cabioch, 1961; Holme, 1961; Brun, 1969), with population densities varying from 340/m2 (Vevers, 1952) to 2196/m2 (Brun, 1969). These populations seem to be permanent features of the sea bed since the aggregation sampled by Allen was in the same position as that photographed by Vevers fifty years later.

INTRODUCTION

Various authors during the last century (Johnston, 1847; Hincks, 1868, 1880) and more recently (D. Eggleston, unpublished†) have recorded a number of species as epizoites on the perennial bryozoan Flustra foliacea (L.) (Table 1); but the ecology of the ‘community’ (Hedgpeth, 1957) of epizoites and their interaction with the living substratum has never been studied. The sessile fauna of Flustra fronds includes species of seven different phyla, but it can be said of only a few that the fronds provide their typical habitat. For example, the barnacles are never very numerous and the lamellibranchs rarely reach adult size. This paper is concerned mainly with the most common epizoites: the hydroids and bryozoans. The distribution and orientation of some of these species on the fronds are of ecological interest.

INTRODUCTION

Algal-invertebrate symbiosis is common among species of acoelus Turbellaria in both marine and freshwater environments (Droop, 1963; Buchner, 1965; McLaughlin & Zahl, 1966). Associations involving these organisms exhibit broad variations in the amount of integration achieved through the reciprocal relations of hosts and symbionts. In the symbiosis involving Convoluta roscqffensis Graff, the maximum degree of intimacy is achieved, and the host appears totally dependent on its symbiont for its nutritional requirements (Keeble & Gamble, 1907; Keeble, 1910). This type of closed symbiosis is unknown in other invertebrate phyla and may even be unique among turbellarians. Similarly, the association between Amphiscolops langerhansi (Graff) and a unicellular alga is a typical example of the more common, open or facultative symbiosis. Both species (with their algal partners) are potentially useful as investigative tools in the study of cellular interaction in algal-invertebrate symbiosis, and may provide the basis for understanding the broader aspects of cellular integration in metazoan tissues. Recent studies of C. roscqffensis provide a basis for understanding the biology of the symbiosis which it sustains (Parke & Manton, 1967; Provasoli, Yamasu & Manton, 1968; Provasoli, Yamasu & Mabuchi, 1969). The present communication is intended to provide similar information on the association found in A. langerhansi.

INTRODUCTION

A considerable amount of data now exists on the relationship between metabolism and body size in a wide range of organisms from bacteria and protozoans through to large mammals. Much of this information has been reviewed by Kleiber (1932, 1947), Brody and Procter (1932), Brody (1945), Zeuthen (1947, 1953), Hemmingsen (1950, i960) and Bertalanffy (1957). In general the metabolism has been shown to be proportional to a fractional power of the body weight thus eggs, the larger metazoan poikilotherms and even homoiotherms is proportional to a constant power of the body weight. This factor has been shown to be 0.751 ± 0.015 by Hemmingsen (i960). Superimposed upon this general relationship are variations according to the weight range of the organisms concerned. Thus both Zeuthen (1953) and Hemmingsen (i960) have shown that the value of the constant b for unicellular organisms is approximately 0.7 (Zeuthen, 1953) or 0.751 (Hemmingsen, 1960), whilst that for small metazoans is 0.95 (Zeuthen, 1953) or 1.0 (Hemmingsen, 1960). Finally, the slope of the line relating the metabolism to body size in larger metazoans is 075 (Zeuthen, 1953) or 0.751 (Hemmingsen, 1960). That is, the value for b — 1 in equation (2) is likely to be between -0.3 and -0.249 in unicellular organisms; 0 and -0.05 in small metazoans and approximately -0.249 in larger metazoans.

Despite this apparently fundamental relationship between metabolism and body size, there are many instances where for a particular species the relationship may not apply. Indeed in some species the metabolism may vary in its relationship to body weight according to conditions such as salinity, shore level, experimental temperature and acclimation temperature.

INTRODUCTION

Paramysis arenosa (G. O. Sars) occurs quite commonly in sandy bays on the west coast of Scotland. It is common in Kames Bay, Millport, Brodick Bay on Arran and on Fairlie Sands in the Firth of Clyde. It has been taken in Loch Crinan, Argyll and at Ganavan Sands and Loch Nell Bay, both north of Oban, Argyll. It is common in Firemore Bay, Loch Ewe and in Gairloch and Gruinard Bay in Wester Ross.

INTRODUCTION

There are more than twenty species in the genus Neomysis Czerniavsky, of which the only British representative is N. integer (Leach). This is one of the commonest species of mysids round the coasts of Britain. It lives in estuarine, brackish-water situations and Tattersall & Tattersall (1951) have summarized its distribution. The present investiga- tion has added many records from the west coast lochs of Scotland: Lochs Striven, Riddon, Fyne, Gilp, Ranza in the Firth of Clyde; Lochs Craignish, Feochan, Etive, Creran, Shuna, Linnhe, Eil and Torridon farther north. The biology of Neomysis species is much better known than that of species in other genera:N. americana (Smith) has been studied by Cowles (1930), Whiteley (1948), Hulburt (1957) and Hopkins (1965); the biology of N. awatschensis (Brandt) has been examined by Ii (1964) and Turner & Heubach (1966), that of N. czerniawskii Derjavin and N. intermedia (Czerniavsky) by Ii (1964), that of N.japonica Nakazawa by Ishikawa & Oshima (1951) and Ii (1964), that of N. rayii (Murdoch) and N. spinosa Nakazawa by Ii (1964).

INTRODUCTION

In an earlier paper (Warwick & Buchanan, 1970) the structure of the nematode communities at three stations off the Northumberland coast was compared. It was shown that the offshore mud community at station ‘C’ was faunistically the most homogenous. This station has been selected for a more intensive investigation of meiofaunal production since it provides the simplest situation for study, and furthermore the type of nematode community found here is thought to be of common occurrence in similar sediments round Northern Britain.

INTRODUCTION

In earlier papers we have given an account of work on the three kinds of chambered shells which are found in living cephalopods, i.e. those of Sepia, Nautilus and Spirula, and shown that, although these animals differ markedly from one another in the structure of the shell and its position in the animal, there are nevertheless great similarities in the pattern of events leading to the formation of a new chamber and the way in which liquid is pumped out of it and gas diffuses into it (Denton & Gilpin-Brown, 1961 a, b, c; 1966; Denton, Gilpin-Brown & Howarth, 1961, 1967). We advanced the hypothesis that this pattern must have been the same for all the chambered shelled cephalopods, including the fossil nautiloids, ammonites and belemnites.

The four species studied (Bledius spectabilis, Heterocerus fenestratus, Dichirotrichus pubescens and Cillenus lateralis) are most commonly found in a region delimited by the anaerobic mud of the lower bank and the dense marsh bordering the drainage channels in tidal salt-marshes at Scolt Head Island, Norfolk.

Experimental submersion of the beetles in sea water was found to induce an apparent anoxic condition which was associated with a drastic reduction in oxygen consumption. On return to air there was a large increase in oxygen consumption characteristic of an appreciable oxygen debt.

The use of the physiological responses to submergence as an indicator of effective contact with water revealed that their subterranean mode of life largely prevents direct exposure of the beetles to sea water in natural conditions. A significant proportion of Heterocerus fenestratus were, however, found to be vulnerable to flooding by sea water during tidal coverage of the burrow system.

These results are considered in relation to the observations made on the behaviour and burrowing activity of the various species.

INTRODUCTION

Much of the rocky coast of Norway is known to form a favourable habitat for Laminaria hyperborea (Gunn.) Foslie. In June and July 1965 observations of this species and its competitors were made both in an area near Espegrend (60° 16.23′ N, 5° 13.42′ E), 15 km south of Bergen, and near Tromso (69° 39.2′ N, 18° 57.6′ E) for comparison with populations round the Isle of Man.

The ctenostomatous ectoproct Triticella koreni (G.O. Sars) occurs mainly on Calocaris macandreae (Bell) and Nephrops norvegicus (L.) but also on other Crustacea including Upogebia deltaura (Leach), Goneplax rhomboides (L.), etc. (Eggleston, 1969). Off Northumberland T. koreni occurs mainly on C. macandreae. C. macandreae moults from September to December (Buchanan, 1963).

In order to investigate how the ectoproct copes with this annual substrate loss collections of C. macandreae made in all months were examined. Some of the material was provided by Dr J. B. Buchanan; all came from mud bottoms 40 fathoms deep east of Blyth and was collected between 1961 and 1963. Ten random C. macandreae were taken from each month's collection. One periopod on each Calocaris was selected by the use of random numbers. The number of T. koreni zooids, the number of developing zooids, the number of oviparous zooids and the number of free eggs in each oviparous zooid on each selected limb were counted.

The data recorded from the ten limbs from each collection examined are shown in Table 1.

T. koreni zooids are hermaphrodite. The gonads and free spermatozoa and eggs can be seen through the translucent body wall. Spermatozoa and eggs rarely occur in quantity in the same zooid. Some zooids are so packed with sperm as to appear opaque; up to thirty-one eggs were seen in other zooids. The egg is small and unpigmented; the larva is unknown.

From November to June T. koreni colonies grow rapidly and have a high proportion of developing zooids. From July to October growth slows and reproductive activity increases.

INTRODUCTION

The caesium radionuclides, caesium-137 and caesium-134, are important constituents of aqueous radioactive effluents discharged to the environment of the United Kingdom from fuel re-processing plants and nuclear power stations (Howells, 1966; Mitchell, Harvey & Smith, 1968; Harvey, Baker & Mitchell, 1969). Their accumulation by marine fishes has been the subject of several previous studies, beginning with that of Chipman (1959) who noted that caesium-137 was accumulated in the flesh of the killifish (Fundulus heteroclitus) and that accumulation continued even after a period of 72 days. Similarly, Hiyama & Shimizu (1964) showed that the muscle of the common goby (Acanthobus flaviamus) continued to accumulate caesium-134 from sea water after periods of 30 days. Baptist & Price (1962) have examined the whole body uptake of caesium, by absorption from sea water, in two marine species, the flounder (Paralichthys dentatus) and the Atlantic croaker (Micropogon undulatus), and they also investigated the accumulation, tissue distribution and excretion of caesium-137 in the croaker, the little tuna (Euthynnus alleteratus) and the bluefish (Pomatomus saltatoux), following oral administration of single doses. These authors concluded that the heart, liver and spleen of the croaker absorbed caesium-137 from sea water at a faster rate than the muscle, and that orally administered caesium-137 was rapidly absorbed from the digestive tract. Tissue distributions were similar in the croaker, bluefish and tuna. The retention of caesium-137 in croaker tissue was described as a multiple rate process. In later experiments Hiyama & Shimizu (1969) compared turnover rates in various organs and tissues following uptake from sea water and from single injection experiments, and obtained good agreement between the values from the two methods.

INTRODUCTION

Ecological studies of Eider Somateria mollisima, Shelduck Tadorna tadorna, Redshank Tringa totanus [Aves], and Flounder Platichythys flesus [Osteichthys], in the estuary of the River Ythan, Aberdeenshire, have entailed investigations of their food requirements, and there is evidence to suggest that Hydrobia ulvae [Gastopoda], as a numerous food item common to all, may in some instances have influenced their breeding success and numbers in some years. In order to get an index of abundance of Hydrobia, the Ythan population has been sampled four times a year since May 1963. The full results of this sampling programme are being published separately. At the same time data on the annual cycle of Hydrobia were collected from one area (transect number 3, Fig. 1), on the assumption that breeding onset and intensity would be the same in other parts of the estuary in any one year.

INTRODUCTION

The problems involved in the identification of freeliving marine nematodes have stood in the way of ecologists for some time. Although considerable advances are now being made on the continent (particularly in Kiel Bay and the Mediterranean) and in North America, our lack of knowledge of the British species is still lamentable. In order to rectify this state of affairs to some extent, a study of the distribution of nematodes in the Exe estuary was planned to cover as wide a spectrum of physical and chemical conditions as possible, ranging from fine muds with a low interstitial salinity at the head of the estuary to coarse sands with a high salinity at the mouth. It is hoped that the characterization of the fauna of various habitats in the estuary will form a basis for further ecological studies in other areas. Not surprisingly, a large proportion of the species found were new British records, and some new to science. The fourteen species of this latter group discussed in this paper are described elsewhere (Warwick, 1970).

INTRODUCTION

Oxyrrhis marina Dujardin is among the few phagotrophic micro-organisms, and the only dinoflagellate with this mode of nutrition, to have been cultivated under axenic conditions. In common with most other phagotrophs studied, Oxyrrhis had to be supplied with a natural source of lipid growth factors for axenic cultivation, lemon rind or grass extracts in this instance (Droop, 1959). The eventual replacement of these natural sources by ubiquinone (Droop & Doyle, 1966) cleared the way for the development of a completely denned culture medium for Oxyrrhis and the completion of the nutritional study, the water-soluble nutrients having been fully worked out previously (Droop, 1959). However, identification of this requirement immediately raises two questions. The answer to the first, whether ubiquinone is the only lipid required, appears to be in the negative, and the details of an additional, fairly specific, steroid requirement are presented in the second part of this paper. The other question concerns the specificity of the quinone requirement. Is the quinone merely a convenient source of the benzene ring – mammals require at least one aromatic compound in the diet – or does it act as a true growth factor, in which case the requirement would be unique and would have more than protozoological interest?

INTRODUCTION

Certain sand-dwelling amphipods occur either in the intertidal or in the sublittoral zone and extreme low-water springs (E.L.W.S.) has been taken as a convenient dividing line between these two habitats. Previous workers have concentrated mainly on one or other of these contiguous regions. General studies of the in-fauna of intertidal sand on the Isle of Man include those of Pirrie, Bruce & Moore (1932), Jones (1948) and Southward (1953). The in-fauna of sublittoral sandy deposits around the Isle of Man has been studied by Jones (1940, 1951, 1956) and Fincham (1969a). However, Mclntyre & Eleftheriou (1968) working at Firemore Bay, Loch Ewe showed that the intertidal and shallow-water sand regions should be regarded as a unit. Faunal distributions were not always discontinuous about E.L.W.S.

INTRODUCTION

Balanus balanoides (L.) is a cross-fertilizing hermaphrodite. Insemination takes place in November in North Wales. Spermatozoa are deposited in the mantle cavity of a receptive individual by the extended penis of a neighbouring ‘acting male’. If a receptive individual – that is one that will accept insemination – is examined before oviposition takes place, the oviducal glands are found to be distended by a clear fluid (Walley, 1965). Oviposition follows insemination and fertilization is external, taking place within the confined space of the mantle cavity. The oocytes enter the mantle cavity, via the paired oviducal glands, and become enclosed in a pair of thin membranes. These membranes, enveloping the egg masses, are formed by distension of the elastic sacs secreted by the oviducal glands (Walley, 1965) and the spermatozoa have to pass through them in order to fertilize the eggs. If spermatozoa which have been deposited in the mantle cavity of a receptive individual are removed and examined before oviposition begins, they are immotile. If, however, they are examined several minutes later, during oviposition, they are found to be swimming vigorously (Barnes & Crisp, 1956): they have apparently been activated. The work described in this paper yields some information on the activation of the spermatozoa in B. balanoides, supplements recent work on the structure of cirripede spermatozoa (Brown, unpublished2; Turquier & Pochon-Masson, 1969; Bocquet-Vedrine & Pochon-Masson 1969; Munn & Barnes, 1970), and fixes the time within the sequence of maturation divisions of the oocyte at which fertilization takes place.

While it is known that the hydroid Clytiajohnstoni (Alder) may get broken off and drift in the plankton (Russell, personal communication), rounding off into pelagic colonies, there is, however, no record of the hydroids Sarsia tubulosa (M. Sars) and Tubularia larynx (Ellis and Solander) living under similar conditions.