The biology of Praunus flexuosus (Müller) is closely similar to that of P. neglectus (G. O. Sars). In both species the over-wintering population matures and breeds in the early spring and summer to produce a spring generation of young which are evident in the population in May or June. The members of the over-wintering population die off in July or August. Some members of the spring generation become sexually mature and breed in the early autumn. The progeny of this autumn breeding, along with the bulk of the spring generation, form the over-wintering population. These species are omnivorous feeding on animal and plant debris and also preying on small crustaceans, very frequently harpacticid copepods. The maximum brood size found in P. flexuosus was 63 and in P. neglectus was 81. The biology of the populations on the west coast of Scotland is briefly compared with that of populations in Port Erin, Isle of Man, in Norway and at Roscoff.

The seasonal maxima of occurrence of 23 species of mysids are examined; the numbers caught of a further four species were too small to draw any conclusions from. The evidence suggests that all species, except possibly two, aggregate; not enough information is available on Acanthomysis longicornis and Heteromysis fortnosa. The types of aggregations formed, whether population swarms or breeding aggregations, are unknown in 10 species. There is evidence of shoal and/or swarmformation in 12 species and of breeding aggregations in 7 species. All species known to form swarms live in shallow water; Leptomysis gracilis is the only species living in deep water that shows evidence of swarm formation. All other deep-water species aggregate, some for the purposes of breeding. Negative phototropism of individuals is suggested as a mechanism initiating aggregation of species in the bottom of deep-water basins. Reaction of one individual to another individual or groupof individuals (social behaviour) is considered necessary to intensify the initial degrees of aggregation and to maintain the integrity of shoals or breeding aggregations once formed. Parallels are drawn between aggregations of mysids and those of euphausiids.

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

In common with other plants, marine phytoplankton will only thrive if they are able to obtain essential trace elements. There is some evidence that shortages of available iron and manganese may occasionally restrict the growth of these organisms (Harvey, 1939, 1947). However, other essential trace metals are present in the sea at concentrations which, although very low, appear to be adequate to sustain abundant growth. The concentrations of trace elements necessary for optimum growth differ considerably from species to species (see e.g. Harvey, 1947; Goldberg, 1952). Krauss & Porter (1954) have demonstrated that manganese, iron and zinc are taken up by the freshwater alga Chlorella pyrenoidosa in proportion to their concentrations in the medium. However, this is not true for all elements, at least so far as the larger algae are concerned (Young & Langille, 1958). The concentrations of trace elements present in phytoplankton grown in culture may also depend on the age and density of the culture. Thus, Hayward (1969) has shown that although iron and zinc were initially rapidly taken up by Phaeodactylum tricornutum from a medium rich in chelated forms of these metals, their concentrations in the cells decreased as their numbers increased. The uptake of trace elements is not confined to those which have a definitely established physiological function.

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.

Mytilus edulis L. is shown to acclimate to high and low temperature under laboratory conditions. The warm and cold acclimation of oxygen consumption, filtration rate and assimilation efficiency are described for groups of animals maintained at three food-cell concentrations. Complete acclimation (Precht's type 2) of oxygen consumption and filtration rate occur within 14 days. There is no change in assimilation efficiency within the 28-day experimental period. The results are integrated and discussed in the context of a simple energy budget. In terms of the energy budget there exists a marked contrast between warm and cold acclimation. An “index of energy balance” is proposed in order to assess the state of the energy balance. When animals are fed above the maintenance requirement the energy budget remains in an equilibrium state during cold acclimation, whereas the acclimation to a warm temperature regime disrupts the balance and represents a physiological stress. During warm acclimation, prior to the re-establishment of an energy equilibrium the blood sugar level increases, suggesting that the animal is required to mobilize and utilize its energy reserves.

INTRODUCTION

The results of bottom line fishing have shown that significant catches can be made down to 3000 m depth at several positions on the continental slope off south-west England (Forster, 1968). But when hooks were lifted off the bottom either deliberately or accidentally very few fish were taken. The chances of catching bathypelagic fish in mid-water by baited hooks therefore seemed slender. In 1966 when thin white lines were tried, they were bitten through several times, always at about 1100 m depth. Trials with baited hooks set on thin wire lines in 1967 showed that the black scabbard fish Aphanopus carbo could be taken at this depth. In 1968 and 1970 during the course of short voyages on R.V. ‘Sarsia’ further vertical line hauls were made, taking Aphanopus regularly and also two species of deep-water squaloids.

Schistomysis kervillei (G. O. Sars) is a common species in Loch Ewe, Gairloch and Gruinard Bay in north-west Scotland and a rare species in the Firth of Clyde. It breeds throughout the year but most intensely in the spring and summer, to produce a spring and summer generation of young. The maximum number of young found in a marsupium was 47. The species is omnivorous. Its biology is briefly compared with that of S. spiritus (Norman) and S. ornata (G. O. Sars).

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).

A micro-analytical scheme for the determination of protein, total carbohydrate, freereducing substances, total lipid, phospholipid and RNA levels in marine invertebrate larvae is described and discussed. The scheme is designed for use with 1–2 mg dry weight of tissue. Values of 171·0, 15·03, 50·4 and 11·58 μg/mg dry weight of larvae (flesh + shell) are given for the levels of protein, total carbohydrate, total lipid and RNA respectively, in newly released larvae of Ostrea edulis L.

INTRODUCTION

The retinae of deep sea fishes have been studied by optical microscopy by several authors. Brauer's (1908) work is the most important early account, and the major recent work is that of Munk (1966a). In this monograph he reviews previous papers including that of Contino (1939), Franz (1907), Hanyu & Ali (1962), Verrier (1931), Vilter (1953, 1954a, b) and Wunder (1958), and also describes the eyes of a number of species himself. Since then Munk (1966b and 1968) has described other species by optical microscopy. Locket (1969, 1970) has used electron microscopic methods of fixation to study two species by optical and electron microscopy. These two fishes, Poromitra nigrofulvus and Sternoptyx diaphana, are not closely related and have different retinal structures. Poromitra has banks of rods in its retina, a condition first described by Vilter (1953) in Bathylagus; Sternoptyx has a single layer of long rods, a condition also found in the present species. The earlier authors worked on material collected during research expeditions and preserved in alcohol or formalin. During the 1966 biological cruise of R.R.S. ‘Discovery’ Locket was able to fix eyes from deep-sea fish with a view to electron microscopy. Though the fixation is not perfect, it does preserve much ultrastructural detail and interspecies variation in retinal structure can be studied in this material.

The concentration of copper in Nereis diversicolor O. F. Miiller is roughly related to the total concentration in the sediment and particularly high concentrations are found where mining pollution occurs. In contrast, the concentration ofzinc in Nereis remains remarkably constant despite wide variations in the environment and appears to be accurately regulated.

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.

An examination of the postlarvae of the goby Lebetus Winther collected in the neighbourhood of Plymouth shows that there are two forms, separable on degree of development of the fins, meristic characters and body proportions. The differences are sufficient to indicate that there must be two species whose identity can only be made certain by rearing, since the original two species L. orca (Collett) and L. scorpioides (Collett) have recently been regarded as one species showing sexual dimorphism.

INTRODUCTION

Until recently only two marine members of the phylum Tardigrada were known to occur in Britain. Echiniscoides sigismundi (Schultze), was found associated with mussels (Green, 1950) and intertidal barnacles (Crisp & Hobart, 1954). The interstitial species, Batillipes mirus Richters, was located at beaches in North Wales (Boaden, 1963) and Strangford Lough in Northern Ireland (Boaden, 1966).

Interstitial tardigrades have been reported from several localities around the North Sea. The fauna of the German coast is particularly well studied; Schultze, 1867; Richters, 1908, 1909; Schulz, 1935, 1951, 1953; Grell, 1937; Remane, 1940; Freidrich, 1963; Riemann, 1966a, b; Schmidt, 1969. This German fauna includes three species of Batillipes and single representatives of five other genera. In addition, E. sigismundi and B. mirus have been found in Norway (Tambs-Lyche, 1939–40). Along the French coast of the English Channel, eight species from six genera are reported. While most studies originated at RoscofT, including Cuénot, 1892; Cantacuzène, 1951; Guèrin, 1960; Swedmark, 1951, 1955, 1956a; Swedmark & Teissier, 1967; Thulin, 1942, two species of Batillipes have been located elsewhere on the northern coast of France (Renaud-Debyser & Salvat, 1963).

In recent surveys of beaches in Britain, additional tardigrades have been located. Gray & Rieger (1971) reported their occurrence at several beaches on the north-east coast of Yorkshire, especially at Stoupe Beck, Robin Hood's Bay and Filey Beach near Scar-borough. Also, A. D. Mclntyre has found them in his collections at Firemore Bay in Loch Ewe on the west coast of Scotland. This paper describes specimens generously provided from these two studies.

The epithelial receptors of Nassarius are primary sense cells. The sensory endings are abundant on the tentacle tips, anterior border of the foot and ventral external surface of the siphon tip. Densities are a small multiple of 1032 endings/mm2.

Type 1 ciliated endings are of ubiquitous occurrence. The ultrastructure of type 1 endings is uniform, though the static and motile bundles of sensory cilia may be distinguished by the random or uniform orientation of the ciliary subfibrils and basal feet. Ciliated receptors probably include both chemo- and mechanoreceptors.

A distinct ultrastructural type of sensory ending (type 2), confined to the siphon tip, consists of a small pit in the peripheral dendrite close to the epithelialsurface. The pit contains whorled microvilli and a few cilia. It may be photoreceptive.

A small amount of convergence of sensory information may occur in peripheral nerve.

Determinations have been made of paniculate iron in samples collected from Southampton Water over a period of 2 years. Concentrations of 106–1046 ug/l. were found. Total amounts of paniculate matter ranged from 1·3 to 48·6 mg/1., of which iron constituted 0–5–14%. Amounts of paniculate matter and paniculate iron showed a highly significant correlation. For one station where wind-speed data were available there was a highly significant correlation between the amount of particulate matter and the mean daily wind speed for the 4 days prior to sampling. No clearly defined seasonal variation in the amounts of particulate matter or particulate iron was found. The concentration of particulate iron in the estuary appeared to be dominantly controlled by meteorological and hydrological factors.

INTRODUCTION

The atomic ratio of oxygen-consumed to ammonia-nitrogen excreted by marine organisms (O:N ratio) is more conveniently and precisely determined with current analytical procedures than the respiratory quotient (R.Q.). When an organism is oxidizing protein exclusively the O: N ratio will be low, less than 7; it will be high when either fat or carbohydrate is oxidized.

Determinations have been made, by neutron activation analysis, of the concentrations of tantalum in the tissues of some common crustaceans, molluscs, echinoderms and tunicates of coastal waters of southern England. The concentrations ranged from less than 0·01 ppm dry weight in the muscle of Mytilus edulis to 2 ppm dry weight in Neomysis integer. Two ascidian species showed concentrations of about 0·2 ppm dry weight in the whole organism. The measurements support the generalised concentration factors which have previously been assumed in assessing the radiobiological significance of discharges of radioactive tantalum to the marine environment.

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.