A new scyphomedusan is described which was collected on a dive by U.S. research submersible Deepstar 4000 at 723 m. in the San Diego Trough. The specimen was incomplete. It is characterized by a gastro-vascular canal system in the form of a uniform network, and by the unusual form of its gonads. Its systematic position is uncertain. The medusa is named Deepstaria enigmatica gen.nov., sp.nov.

Larvae of the oyster (Ostrea edulis L.), when released, can live for several days without food, and can grow to full size when subsequently fed. Energy is supplied by protein, carbohydrate and lipid of the larval body, all of which decrease during starvation. The measured decreases are sufficient to account for the energy expended as indicated by oxygen consumption.

The larva of the dolichopodid fly Aphrosylus celtiber Haliday is an omnivorous carnivore in the intertidal zone. It pupates in an air-filled cocoon of debris and a secretion of the labial glands. The pupa has plastron-bearing spiracular gills that have been evolved from respiratory horns similar to those of recent terrestrial Dolichopodidae.

Although the spiracular gills are pupal structures, they are the chief respiratory organs of the young adult, i.e. the pharate adult, before it emerges from the cocoon. At the pupal-adult apolysis the layer of epidermis that secreted the gill wall and the layer that secreted the spiracular atrium are left behind in the lumen of the gill, together with blood, as the body wall epidermis retracts away from the pupal cuticle. A thin sheet of cuticle, the basal membrane, is secreted across the opening into the gill lumen at this time. The epidermis and blood in the gill lumen are thus completely isolated from the haemocoele of the living animal by the basal membrane, a layer of moulting fluid, and the adult cuticle. The tissue contained in the respiratory horns of terrestrial Dolichopodidae is isolated in a precisely similar manner.

The tissue isolated in the lumen of the gill of Aphrosylus does not degenerate until after the pupal-adult ecdysis. It seems to be discarded because, on balance, its loss is less damaging than the cost that would be incurred in other ways by its absorption or retraction into the body of the adult. For instance, in order to absorb the tissue in such long appendages, or to retract all of the epidermis from within them, would necessarily prolong the moulting period, a period when the insect is particularly vulnerable.

Two unusual specimens of Raja richardsoni Garrick from the N. Biscay area lacked part of the snout, apparently because it had been bitten off.

The conchocelis-phase of Porphyra tenera Kjellman has been grown in in vitro culture, and subjected to a variety of daylength treatments.

Details of the culture apparatus designed for these treatments are given, and quantitative techniques, which have been devised for estimating the growth and reproduction of the alga, are described and discussed.

Growth was found to be directly proportional to daylength within the range 8–16 h, but abundant sporangia were only formed in daylengths of 10 h or less. The interruption of a 16 h dark period by 1 h of light completely inhibited the production of sporangia, but exposure to 8 short-day cycles, followed by long days, induced the formation of as many sporangia as were found after 25 short days. These results are discussed with reference to the photoperiodic responses of flowering plants.

Spirorbis vitreus (Fab.), an arctic form, seems to be absent from Wales and most of England, but is generally abundant off the west coast of Scotland and also occurs in certain localities off Ireland, the Isle of Man, Cornwall and Brittany (which is probably its southern limit in Europe). Its range thus extends farthest down our western coasts, a distribution which is characteristic of various other northern and southern forms that are near the limits of their geographical ranges. Such species presumably benefit from the equable temperatures, adjoining deep water, and this winter-breeding species of Spirorbis also needs freedom from abrasion.

The tubes of juvenile S. vitreus are very different from those of adults. The distribution of uncini on the abdomen shows a remarkable bilateral asymmetry, as in S. spirillum.

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.

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.

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.

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).

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.

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.

Studies of a natural population of N. virens Sars at Southend reveal that the oocytes take a little over a year to mature. After a period of relative quiescence they grow rapidly between September and December and then increase little in size until early May. Within a given specimen small oocytes are more variable in size than large ones. Sperm develop fully from coelomic sperm plates in about eight months, and are mature by the beginning of May. There is a period during which they are characteristically clumped in quartets.

In experiments in Cornwall and Yorkshire 214 marked lobsters (Homarus vulgaris M. Edw.) were returned after moulting. Of these a number had moulted more than once, and the separation into once-, twice- and three-times-moulted lobsters was achieved using probability paper.

There was no significant difference in growth of lobsters from the two areas. It is concluded that the best method of plotting growth in lobsters is to plot carapace length before moulting against carapace length after moulting.

It is concluded that male lobsters show arithmetic growth over the size range 68–123 mm carapace length, adding a constant mean increment of 9.8 mm carapace length at each moult.

It is concluded that arithmetic growth, with a mean increment of 8.4 mm, adequately describes the growth of female lobsters over a small size range centred on a mean size of about 85 mm, but would lead to inaccuracies over a wider size range.

The concept of arithmetic growth in relation to the general growth pattern is briefly discussed.

Introduction

In a population study a knowledge of the growth rate is essential. In crustaceans estimation of the growth rate is complicated by two factors: first, it is usually not possible to age the animals, and second, the growth rate is made up of two components, the increase in size at moulting and the frequency with which moults occur.

The present paper presents data on the growth of lobsters at a moult, obtained from field experiments conducted in Cornwall in 1957–59, and in Yorkshire in 1958 and 1960.

Several aspects of polymorphism in Hydractinia echinata (Fleming) have been examined. Polymorphism in Hydractinia appears to be the result of inhibition of the normal developmental sequence and not the result of direct genetic control. The inhibition is mediated by both intrinsic and extrinsic factors. The former are responsible for the formation of reproductive zooids in the colony, but this process may be accelerated by extrinsic factors (crowding, increased pCO2). It is suggested that intrinsic factors consist of an inducer or growth stimulator produced in the hypostomal region of the polyps and an inhibitor of growth and differentiation produced by dividing cells beneath the hypostome. The ratio of these two factors throughout the colony ultimately determines the polyp type which will be formed.

Tissues from a number of marine species were treated with a variety of solutions, including 1% of the major ‘detergent’ (B.P. 1002) used in attempting to disperse the oil from the ‘Torrey Canyon’ and 1% of each of the three major constituents of B.P. 1002, two of which are non-ionic surfactants.

The extracts were submitted to vertical starch-gel electrophoresis in order to measure both the effect of the detergent in facilitating the breakdown of cellular structure (extractability), and the irreversible effect on activation or inhibition of various enzymes and other proteins.

The proteins studied include a variety of NAD- and NADP-linked dehydrogenases, esterases, blood and nerve haemoglobins, plasma proteins, egg white and yolk proteins, and r-phycoerythrin.

The results confirm the general opinion that detergents increase the extractability of proteins from cells. In particular lipoprotein systems are altered, e.g. ‘fast’ serum lipoprotein in fishes (and other vertebrates). Other effects are also observed, e.g. sole but not turbot haemoglobin is rendered relatively insoluble, probably because the detergent stabilizes haemoglobin binding to other components in the erythrocyte. Certain enzymes, e.g. some esterases and amylases, are activated—a not surprising observation. However, a few enzymes are altered in electrophoretic mobility or in activity in a way that one might not expect, e.g. bass Morone labrax lactate dehydrogenase.

The results indicate that ‘oil-spill’ detergents and their constituent surfactants are biochemically quite powerful agents. It is too early to attempt to correlate in vitro and in vivo observations but there is an indication that starch-gel electrophoresis provides a useful supplement to more conventional methods used in the studies on complex pollution problems.

The eye of the larval herring has only single cones in the retina. They are characteristic in ultrastructure at this stage with a striated outer segment, an ellipsoid packed with mitochondria and with a connecting cilium at the junction. Cones are gradually added at the margin of the retina as the larva grows. There are no retinomotor responses in the larval eye. It has, however, adult characteristics in the postero-ventral area temporalis (though it is undifferentiated at this stage) with its blindly ending anterior pocket and in the falciform process closing off a trough-shaped ‘ancillary’ eye.

At metamorphosis (30–40 mm) a number of changes occur: the area differentiates, twin cones and the rods appear, the latter perhaps developing from cells originating in the bipolar layer and migrating to a position inside the external limiting membrane. Retinomotor pigment migration and change in length of the cone myoids also develop when the eye is subjected to changing light intensities, the threshold being 1.0–0.01 me (metre candles).

In the adult eye the fully developed retina has an area temporalis packed with single cones giving high acuity on the main visual axis, which is in the upperfore direction. The lens presumably gives accommodation by postero-ventral movement brought about by a postero-dorsal suspensory ‘ligament’ and a ventroanterior falciform process. This process also delimits the area and divides off the ‘ancillary’ eye from the main retina.

Over the whole range of development the cone ellipsoids grow in diameter from 2 to 12 μ and decrease in density correspondingly.

The histology of the spurdog (Squalus acanthias L.) testis was observed through a complete annual cycle. The maximum sperm accumulation coincided with the breeding time as defined by the biennial female cycle. Degeneration of spermatogonia was observed following breeding. The band of degenerate germinal ampullae was identical to that described as occurring in Scyliorhinus canicula (L.) following pituitary ventral lobectomy. This suggested a resting phase in the production of a specific pituitary gonadotrophin lasting for about four months. All spermatocytes were transformed to spermatozoa within 12 months. 3β-Hydroxysteroid dehydrogenase activity was located in semen, in Sertoli cell cytoplasm and in the lumens of mature germinal ampullae. A possible seasonal change in this activity due to the migration of the degenerate band is suggested. Interstitial cells of Leydig could not be observed.

INTRODUCTION

The Scottish-Norwegian stock of the spurdog, Squalus acanthias L., sampled for this study, was shown by Holden (1965) to make an autumn breeding migration from the region of the Orkney and Shetland isles to the breeding areas in the Minch off north-west Scotland. During January and February those females carrying embryos at the end of their second year of development move inshore and liberate their young in shallow water. At this time the ovaries of these fish contain from three to fifteen eggs ready for ovulation (Holden & Meadows, 1964), and observations suggest that copulation, ovulation and the commencement of a further pregnancy follow almost immediately. Following copulation, the spermatozoa must reach the oviducal gland at the head of the oviduct in order that the eggs may be fertilized before they are enclosed by the candle membranes.