An apparatus is described which has been used at three sites in Southampton Water for the continuous collection of sedimenting detritus. The collected detritus was removed at monthly intervals for measurement, and for analysis of the organic carbon and nitrogen content.

The total quantities of dry detritus varied from 4 mg/cm2/month to 980 mg/cm2/month, and because of the variable collection of resuspended bottom material show no clear seasonal variation. The carbon content was 0.1–7.3% of the total and nitrogen varied from 0.02 to 0.62%. The organic content did show some seasonal variation which tended to follow changes in the abundance of phytoplankton.

The amounts of total detritus collected and the organic content are high compared with some other areas and this is thought to be due partly to the high primary productivity of the area and partly to the complex water movements in the estuary.

Introduction

The importance of detritus in suspension in the sea and as a superficial layer on the sediment is well recognized. The quantity of detritus in sea water has been measured (Armstrong & Atkins, 1950; Fox, Isaacs & Corcoran, 1952; Krey, 1950, 1961a, b, 1964; Krey, Banse & Hagmeier, 1957; Hagmeier, 1962) and usually exceeds the amount of living material in suspension by at least a factor of ten. Study of deposited detritus has mainly involved measurement of the amount of organic matter in bottom sediments (Waksman, 1933; Anderson, 1939; Southward, 1952; Morgans, 1956; Sanders, 1960).

In studies of marine productivity it is important to know not only the amount of detritus present in the water column, but also its composition and rate of sedimentation.

The annual cycle of silicate, nitrate and phosphorus in the waters of the Menai Straits is described. The concentration of all these nutrients in these waters is apparently markedly affected by occasional incursions of high-salinity low-nutrient water. The concentrations of nitrate-nitrogen tend to show a general increase throughout the winter months as a result of cumulative contributions from land drainage and run off and the absence of appreciable biological utilization. In contrast, an equilibrium concentration of reactive silicate is maintained over this period following the initial autumnal increase in the concentration of this component. The annual cycle of phosphorus in these waters is also anomalous. Relatively high equilibrium concentrations of this nutrient are maintained during the summer months and unexpectedly low concentrations occur in winter. In conjunction with the biological removal of relatively large amounts of nitrate-nitrogen, this causes anomalously high apparent N: P biological utilization ratios. It is difficult to explain the observed variations in the concentration of phosphate in these waters solely in terms of the equilibrium between biological assimilation and regeneration and advective processes.

Diagnoses and descriptions are given of two new species of marine planktonic flagellates of the class Chrysophyceae; Paraphysomonas imperforata and P. foraminifera. Both possess unequalflagella, the longer pantonemic, the shorter simple. Chromatophores and stigma are absent, phagotrophic nutrition occurring. Surface scales examined by electron microscopy are the best means of identification, those of the latter being perforated by many holes. Each scale of both species has a central dome, bearing a long spine, and a shallow annular fold with a radius half that of the scale.

Annual surveys carried out in south-west England since 1949 show that the arctic-boreal barnacle, Balanus balanoides, which was uncommon or rare in i960, has increased greatly in abundance during the colder years since then. Its numbers now approach those recorded in the 1930's, and there has been a corresponding reduction in abundance of the warm-water species, Chthamalus stellatus.

Gas-liquid and thin-layer chromatography have been used for the determination of 25 amino acids in the hydrolysates of 25 species of marine phytoplankton which had been grown in Erd-Schreiber medium. The general pattern of their distribution agrees with that found by earlier workers; the principal amino acids being glutamic acid, alanine, leucine and aspartic acids. Small amounts of 2-amino-n-butyric and 2-amino-iso-butyric acid together with compounds which have been tentatively identified as 4-amino-n-butyric acid and the 2-amino- and 2,5-diamino derivations of adipic acid were detected in many of the organisms. No differences were found which could be related to the taxonomy of the organisms.

The size-frequency distributions of monthly collections of Aplysia punctata from a sublittoral population in Trearddur Bay, Anglesey, made during the period from July 1964 to October 1965, indicate that the animals live for one year and that the major recruitment to the population occurs in the autumn. The Aplysia in this area are restricted mainly to sublittoral beds of the red alga, Plocamium coccineum, and the majority of animals feed, copulate and deposit spawn on this seaweed. The animals spawn from May, when the sea temperature reaches a minimum of about 9–9·5° C, until about October, with a maximum output of spawn in the late summer when the animals are fully grown. Aplysia in Trearddur Bay do not migrate inshore; instead, they probably colonize the intertidal region after being accidentally washed inshore from the sublittoral habitat. Intertidal and shallow-water Aplysia are larger than those from deeper water possibly because of the greater abundance of food. Similarly, it is thought that Aplysia found in the intertidal zone are brown and olive-green because they eat a particular alga or combination of algae present in this habitat.

The endogenous tidal rhythm of the littoral fish Blennius pholis L. was studied in the laboratory. It was found that there was no difference in the mean level of activity of fish caught on spring and neap tides. The time-interval between activity peaks (the period length) gradually increased in constant darkness. A similar, although not significant, increase was also observed in continuous illumination.

There was no evidence of any diurnal component in the rhythm, but freshly caught fish subjected to alternating periods of light and darkness, equal in duration to the natural period, responded to the onset of illumination by greatly increased activity only when the light period began between activity peaks.

Fish which had been kept in the laboratory for several weeks and had lost their natural rhythm still responded to light by increased activity. This increase was not as great as that shown by freshly caught fish, however, and the response decreased with time. Evidence of re-entrainment of the natural rhythm after 7 days in alternating periods of light and darkness was not found. It was shown that feeding the fish half-way through the 12 h light-period resulted in a reduction of activity after feeding. This did not occur when the fish were fed half-way through the dark period.

A 4h cold shock of 10° C resulted in partial re-entrainment of rhymthic activity in B. pholis.

B. pholis, which alone appears to have a persistent rhythm, differs from certain other fish examined in its strictly littoral habitat and its possible need for activity periods synchronized with the tide.

Thin-layer chromatographic procedures using silica gel and glucose have been employed for the examination of the pigments of twenty-three species of marine phytoplankton, drawn from a number of classes. Several new xanthophylls have been found including one similar to fucoxanthin which is the principal pigment in an, as yet, undescribed member of the Haptophyceae. The pigment array of a species of Olisthodiscus sp. (Plymouth no. 239) differs considerably from that of members of the Xanthophyceae and this species is probably incorrectly classified.

A study has been made of the nitrogenous compounds excreted by Calanus helgolandicus (Claus) collected at Plymouth.

Most of the excreted nitrogen is in the form of ammonia which accounts for 60–100% (average 74.3%) of the total, and some of the remainder may be lost as urea. There is no evidence for the excretion of measurable amounts of amino acids.

Whether the animals are starved or fed they are primarily ammonotelic, and the quantity of ammonia produced at 10° C (3.33 μg/g. dry body wt/day) is not significantly changed when the animals are used at an abnormally high experimental density. This latter condition does, however, lead to the production of large quantities of additional nitrogenous substances that give a positive reaction with ninhydrin.

Introduction

The amounts of nitrogen excreted by zooplankton have been measured by several workers. Harris (1959) used the method of Riley (1953) to estimate the copious quantities of ammonia produced by animals (mainly Acartia tonsa and A. clausi) collected from Long Island Sound; Beers (1964), in laboratory experiments with the chaetognath Sagitta hispida, estimated the excreted ammonia by the procedure of Kruse & Mellon (1952); and Corner, Cowey & Marshall (1965) determined the ammonia excreted by Calanus helgolandicus and C. finmarchicus, using a ninhydrin technique described by Moore & Stein (1954). The methods employed by Harris and by Beers are specific for ammonia: that used by Corner et al. estimates nitrogenous substances (e.g. amino acids) in addition to ammonia, but certain tests were made which seemed to exclude the possibility that these substances contributed significantly to the nitrogen excreted by the animals.

A series of experiments (1963) illustrates the stimulatory effect of 5-hydroxytryptamine on the bioluminescence of Thysanoessa raschii (M. Sars). A further series (1966) shows the effect of 5-HT and of the cinnamanilide anti-serotonin, Squibb 10,643, on the bioluminescence of Thysanoessa raschii and of small Meganyctiphanes norvegica (M. Sars), with and without stimulation by a bright light flash. The suggestion that 5-HT, or something chemically similar, may prove to be a part of the natural control system of the bioluminescence in these euphausiids is endorsed.

The growth rates of Aplysia punctata Cuvier feeding on eight species of marine algae were found to decrease in the order: Plocamium > Enteromorpha > Ulva > Heterosiphonia > Cryptopleura > Delesseria > Laminaria. The brown alga, Desmarestia aculeata, was not eaten. Except for Enteromorpha and Desmarestia, this was also the order found for the feeding preference of sublittoral Aplysia. Enteromorpha was eaten by Aplysia in preference to all the other algae studied.

No clearly defined trends in the concentrations of ash, protein, fat and carbohydrate in the seaweeds were found to account for these differences in growth rates. Absorption of total dry food matter was lowest from the algae giving the poorest growth (45 and 53%, respectively, of the total dry weight consumed for Delesseria and Laminaria diets) and highest from the seaweeds giving moderate growth (71–75% for Ulva, Heterosiphonia and Cryptopleura diets). For Plocamium and Enteromorpha diets the values were 59 and 65%, respectively. Carbohydrate materials were found to constitute 42–75% of the total dry weight of food material absorbed by Aplysia on all the algal diets, and represented the major portion of each. The efficiency of conversion of absorbed food matter into tissues was highest on the algae giving the poorest over-all growth (73% for Delesseria and 40% for Laminaria). For the other seaweed diets the efficiencies decreased in direct relation to the decrease in the value of each for growth of Aplysia (from 35% for Plocamium to 15 % for Cryptopleura).

The same amino acids were found in each food.

The oceanic scyphomedusa Pelagia noctiluca (Forskål) was exceptionally abundant in the coastal waters of Devon and Cornwall in the year 1966. Very young stages were taken only in the months of October, December, January and early February, indicating that the medusa has a restricted breeding season.

A formal description of Rosalina leei sp.nov. (Foraminifera) includes an account of the great morphological variation found among adult agamonts obtained over a period of 14 months from clone cultures. Variation in chamber number, direction of coiling, overall shape, the degree of inflation of the final chamber and suture characters are detailed.

A description is given of the minute epiphytic red alga Kylinia rosulata Rosenv. from collections made in the Plymouth area, and from old herbarium material. The diagnostic characters of this and related species are discussed.

The minute epiphytic red alga Kylinia rosulata (order Nemalionales, sub class Florideophycidae) was first described by Rosenvinge (1909) from dried specimens of Sporochnus pedunculatus (Huds.) Ag., collected from the Northern Kattegat. Kylinia was observed on the terminal assimilatory filaments of the supporting plant. Since the original description, this small plant has had a somewhat confused history from both the taxonomic and nomenclatural points of view. Feldmann(1963) has recently summarized the available data, and has verified the validity of the genus and species as originally described by Rosenvinge (see also Feldmann, 1958). K. rosulata is characterized by the possession of short prostrate filaments arising from a single attaching cell, each cell containing a parietal chromatophore, and with male plants bearing a hyaline hair-like body—called the ‘androphore’ by Rosenvinge (1909) and ‘spermatocystophore’ by Feldmann (1958).

A population of Cucumaria elongata (Düb & Kor.), found in muddy sand off the Northumberland coast, has been sampled from 1961 to 1964. Densities of more than 20 per m were common.

Cucumaria is a suspension feeder, and uses its tentacles to trap suspended paniculate matter. In the absence of mucous glands or cilia on the tentacles, suspended matter is held fast in a covering of mucus which is produced by glands in the pharynx and oesophagus. Each time the tentacles are introduced into the pharangeal lumen in the course of feeding, they pick up a fresh complement of mucus.

The feeding behaviour is seasonal. During the early part of October the animals stop feeding, and remain dormant until late April/early May of the following year.

The results of monthly experiments to determine the oxygen consumption, percentage of total lipid and the volume/dry-weight ratio, have led to the conclusion that during the winter months Cucumaria hibernates.

The effect of temperature on the feeding behaviour is discussed.

Regular quantitative sampling has shown that Cucumaria is slow growing, and over the area surveyed, four different age-groups were found. These have been designated groups I, A, B and C. Group I was estimated to be 2 years old; group A, 6 six years; group B, 8 years; and group C, 10 years old.

Although active sperm and apparently mature eggs were found in specimens collected as far back as 1962, there is no evidence to suggest that any of the age-groups has reproduced.

Anthomedusae of the family Calycopsidae are in general oceanic in distribution. The only species recorded from British waters is Bythotiara murrayi Günther, reported from fairly deep water far offshore from the west and southwest coasts of Ireland. Its early stages have been unknown. A very young medusa caught at the surface in the Firth of Clyde has been reared through several stages, which are described and figured. It is considered to be a young B. murrayi.

Three species of copepods—Calanus finmarchicus (Gunnerus), C. helgolandicus (Claus) and C. hyperboreus (Krcyer)—can be easily and consistently differentiated by starch-gel electrophoresis of a number of their enzymes. The techniques used allow the study of individual variation in natural populations of small invertebrates, some of the variation being readily equated with known genetically based protein polymorphisms in man and other species. C. finmarchicus and C. helgolandicus have 15 enzyme zones in common and differ by 24-28 zones. By the rationale of molecular biology it can be suggested that these two forms differ in two-thirds of the structural genes. The results support the morpho-logical studies by Rees (1949) and Matthews (1966b) and the chromosomal studies by Harding (1963). Hence it is clear that the ‘finmarchicus-helgolandicus’ problem is solved: C. finmarchicus and C. helgolandicus are distinct species. The potentials and problems of biochemical systematics are discussed with particular reference to marine biology.

INTRODUCTION

Electrophoretic techniques have contributed to the solution of many taxonomic problems—for example, the monophyletic origin of ratite birds (Sibley, 1960), the discovery of a sibling species of sea-cucumber (Manwell & Baker, 1963 a; Manwell, 1966a), the status of species and populations of pheasants (Baker, 1965; Baker, Manwell, Labisky & Harper, 1966), the union of the orang-utan, chimpanzee, gorilla and man into one family, the Pongidae (Tashian, 1965), and the recognition of hybridization in lizards (Dessauer, Fox & Pough, 1962) and fishes (Manwell, Baker & Childers, 1963).

The iron content of fresh Mytilus edulis L. from Southampton is usually 20–40 μg/g wet weight after the animals have eliminated their gut contents. In spring some animals have much higher iron contents, sometimes in excess of 100 μg/g. The much higher values reported by some authors are probably erroneous.

Prolonged starvation in sea water of low iron content will not reduce the mean iron content of the animals below 20–25 μg/g. This represents a permanent store. Higher values are produced by a temporary store that is fairly rapidly lost on starvation.

The highest iron concentrations are usually in the digestive gland, which contains the major part of the temporary store, much of which can be regarded as particles being subjected to the digestive processes.

Only iron in the temporary store could be demonstrated by histochemical techniques.

INTRODUCTION

The trace element metabolism of Vertebrates, particularly Mammals has been reviewed by Bothwell & Finch (1962); and Vinogradov (1953) has made a comprehensive review of the elementary chemical composition of living organisms. With notable exceptions, such as the copper in haemocyanin, the trace elements discovered in many invertebrates have no known function. The reported values for many elements differ considerably, depending on the author and the techniques used. In general, despite a number of errors in the values quoted, Vinogradov's data establish at least the order of magnitude of many elements in a variety of animals. Some of these elements occur in greater amounts than would be expected if they were not of metabolic significance. One example, namely iron in Mytilus edulis L., was selected for investigation.

Of the seven British species of Eurydice two are intertidal, three range successively from the immediate sublittoral to the edge of the continental shelf, and two predominate at the edge of and beyond the shelf. Most species have been recorded from the benthos and from surface plankton. E. affinis is recorded for the first time in Britain, among E. pulchra in intertidal sand in the Bristol Channel.

An experimental study of the effects of salinity on the mud-dwelling amphipod, Corophium volutator (Pallas), indicates that, if supplied with mud, it will survive the salinity range of 2.50 %0, and without mud the range 7.5-47–5 %0. Moulting occurred in salinities of 2.6–46 %0, but most frequently in the range 5–20 %0. Growth occurred at a maximum rate in 15.4 %0, and only slightly slower at 4.4 and 30.6 %0; but below 4.4 %0 the growth rate was progressively reduced. Freezing point studies show C, volutator to be a hyperosmotic regulator, having a tissue tolerance range of 13–50 %0. The importance of a supply of mud, and the significance of hyperosmotic regulation are briefly discussed.

INTRODUCTION

The amphipod Corophium volutator (Pallas) is an inhabitant of littoral muds, the populations often reaching high densities. It has been most commonly reported from shores of estuaries, although Zenkevitch (1963) has stated that it may also occur in muds submerged to a depth of 10 m. Segerstråle (1959) has summarized the data available on the occurrence and distribution of C. volutator. Since that date, work has been done on substrate selection (Meadows 1964a–c), on burrowing behaviour (Meadows & Reid, 1966) and on rhythmical swimming activity under tidal control (Morgan, 1965). Many authors (Nicol, 1935; Thamdrup, 1935; Beanland, 1940; Spooner & Moore, 1940; Rees, 1940; Goodhart, 1941; Stopford, 1951; Rullier, 1959; Gee, 1961) have described the substrate in which C. volutator occurs. They have agreed that C. volutator is found in mud or muddy sand, containing approximately 37 % silt or clay.