the reproductive biology of 1045 female (9.5–67 cm (total length (tl)) and 1007 male (9.4–64.3 cm tl) blackmouth catsharks, galeus melastomus, was investigated. the sharks were caught off southern portugal by bottom crustacean trawlers at depths from 209 to 754 m. the sex ratio was 1:1, and this species is sexually dimorphic with males approaching maturity at smaller size than females. sexual segregation appears to be given for the stock within the study area. sexual maturity was reached at a total length above 49 cm in males and above 56 cm in females. mating and egg-deposition take place all year round, with two reproductive peaks of activity, in winter and summer. egg capsules are, on average, 54 mm long and 21 mm wide, with a maximum of 63×25 mm encountered. morphometric measurements of claspers, testes, ovaries, and oviducal glands were suitable for determining sexual maturity of blackmouth catshark.

The swimming musculature of spinal dogfish, Scyliorhinus canicula (L.), was paralysed with curare while recordings were made of the motor activity in the abdominal spinal nerves. Spontaneous, periodic motor bursts of long duration and decreasing frequency were detected during the first 2 h or so of the experiment. The spinal neurons were incapable of sustaining motor activity for more than 1 or 2 h and were dependent on proprioceptive feedback to maintain their excitability; their discharge frequency could, however, be enhanced by un-patterned sensory stimulation.

The spinal neurons on each side of the cord are sufficiently organized to dis-charge alternately but the longitudinal co-ordination of the locomotory wave is disrupted in the absence of phasic sensory excitation.

INTRODUCTION

It has been assumed that the locomotory movements of spinal dogfish, which persist with undiminished vigour for several hours, are co-ordinated in one of two ways. One possibility is that the entire periodic motor output is formulated by the nerve cells of the spinal cord (Gray & Sand, 1936 a, b; Le Mare, 1936); alternatively, it is conceivable that the motor pattern is triggered by sensory signals fed back to the spinal cord by proprioceptors stimulated during locomotory movements (ten Cate, 1933; Lissmann, 1946a, b).

Lissmann attempted to distinguish between these two general hypotheses by cutting all the dorsal roots of spinal dogfish and thereby isolating the spinal neurons from sensory stimulation. His experiments showed that the spinal animal would swim normally even when a considerable number of dorsal roots had been sectioned but as complete de-afferentation produced im-mobile preparations he concluded'that the motor rhythm was ultimately dependent on proprioceptive activity.

In North Wales settlement and metamorphosis of Balanus balanoides occur in May and the animals breed for the first time in the following November. Three weeks after metamorphosis the oviducal glands appear as epidermal invaginations in the basal segments of the first pair of cirri. At first there is no lumen or external duct but these develop during the next fortnight. The wall of the gland is a columnar epithelium which increases in height as the gland increases in size. During mitosis this epithelium exhibits the pattern of cell movements characteristic of similar epithelia in vertebrate embryos.

At Aberaeron, Dyfed, mid-Wales, the two trochid species, Monodonta lineata and Gibbula umbilicalis breed during the summer months. M. lineata showed a discrete spawning period in late July in both 1980 and 1983, whilst G. umbilicalis spawned in August in both years, though with gamete release prolonged into September in 1980. In both species gonad development begins in April/May, and by June the characteristic bimodal oocyte diameter distribution of mature females has been established. Vitellogenesis and the development of a jelly coat around the oocyte begin when the oocytes have a diameter of 70–80 μm, with mature oocytes reaching 140–180 μm in diameter, excluding the jelly coat.

If Arion hortensis be fed on a diet which contains 90Sr, autoradiographs show that the isotope istaken up by the digestive and lime cells of the digestive gland. From the former it passes to th haemocoel; in the lime cells it is concentrated around the calcium spherules. Some of the tracer enters the body through the wall of the intestine. Calcium stores which surround blood vessels and calcium cells in the mantle also concentrate the tracer.

In Aplysia.punctata 90Sr from the surrounding water passes through the surface of the body, and especially the gill; in Acanthodoris pilosa ions which enter the tissues from the sea water accumulate around the numerous calcium concretions in the mantle. These marine molluscs obtain cations directly from the water as well as by way of the food.

There is a slow uptake of strontium ions by the ctenidia of Mytilus edulis, though, even in filtered sea water, the gut is the more important area for their ingress to the body. It is possible that they enter with the mucous feedingsheets. They pass readily into the cells of the digestive gland. Some of the isotope taken in with the food is absorbed by the wall of the intestine; this also occurs in Patella vulgata, in which the intestine provides a much larger area, and in Lepidochitona cinereus.

Mytilus placed in filtered sea water which is activated with 90Sr, so increasing the strontium content by 007%, show the tracer localized for excretion within 10 hr. Ions are aggregated in the pericardial glands, not in the kidney.

Comparison of early shell morphological features of six mytilids from the north-western Atlantic revealed differences useful for species identification and classification. Brachidontes exustus, lschadium recurvum, Geukensia demissa, Amygdalum papyrium, Mytilus edulis, and Modiolus modiolus larvae and post-larvae were cultured in the laboratory. Scanning electron micrographs of the shell and hinge during early ontogenetic stages showed that all species had a long provinculum with taxodont dentition. In addition, provinculum length and number of teeth increased during the larval period in the six species. The small, numerous provincular teeth of Mytilus edulis and the bold, comparatively few provincular teeth of Amygdalum papyrium clearly differentiated these two species. Most species had a low umbo, round posterior margin, and more pointed anterior margin, although Amygdalum papyrium was distinguished by a high, prominent umbo. Distinction of Geukensia demissa and lschadium recurvum larval shells was difficult due to similarity in their shapes and hinge dentition. However, discriminant analysis using larval shell length, shell height, provinculum length, and number of teeth aided in classification of these and other sympatric species.

The distribution and relative abundance of macroepibenthic echinoderms in the eastern English Channel and Irish Sea is described from beam trawl catches. Echinoderms accounted for approximately 29% (by biomass) of fauna captured. A total of 24 species were recorded, including 12 species of starfish. The most frequently encountered species were Asterias rubens and Psammechinus miliaris, which were recorded at 85.5% and 56.0% of stations respectively. Asterias rubens and Ophiothrix fragilis accounted for 63.7% and 25.5% (by biomass) respectively of the echinoderms sampled. Mean echinoderm catches ranged from 0.8-kg h−1 in the north-eastern English Channel to 329-kg h−1 in the south-eastern Irish Sea. The echinoderm fauna was more diverse in the St George's Channel and western Irish Sea (6.7–7.0 species haul−1) than in the north-eastern English Channel (1.9 species haul−1).

1. The method of Dienert and Wandenbulcke permits of the estimation of silicate in solution down to the limit of 0-04 mg. of silica per litre, which cannot be distinguished from zero. The phosphate normally present does not interfere with the reaction.

2. All fresh waters examined were found to contain more silicate than does the water of the English Channel.

3. The water of Plymouth Sound is richer in silicate than that of the sea.

4. At Station El in the English Channel silicate decreases during spring, from a winter maximum of 200-240 mg. per cubic metre, so that from April to June, 1925, the amount left, recorded as 40 mg. per cubic metre, was indistinguishable from zero. At this time the water was stripped of phosphate also. Silicate increased again till early July, decreased in August and again in November ; the times of decrease are suggested as being those of diatom increase.

5. In deep Atlantic water silicate is much more abundant than in the English Channel; values from 360 mg. per cubic metre at 1000 metres to 1200 mg. at 3000 metres were obtained. In winter at any rate the surface value in the Atlantic is similar to that off Plymouth, about 110 mg.per m3 in 1925.

One hundred and fifty intertidal fishes were captured at Jeffreys Bay in July 1996 and February 1997, and at De Hoop Nature Reserve in April 1997, South Africa. Caffrogobius caffer, Chorisochismus dentex, Clinus superciliosus, and Clinus cottoides were all parasitised by haematophagous larvae of the isopod, Gnathia africana, and between 22 and 81% of fishes were infested with 1 to 76 larvae each. Of those fishes examined for blood parasites, 35/46 (76.1%) had an intraerythrocytic haemogregarine identified as Haemogregarina (sensu lato) bigemina, but only Clinus superciliosus and Clinus cottoides were infected. Gamonts of the haemogregarine, some undergoing syzygy, were also present in 50% of stained batches of the anterior hindgut contents of G. africana larvae which had fed on Clinus superciliosus, but were absent from larvae taken from Clinus cottoides and Chorisochismus dentex. This study provides new host records for H. bigemina and further evidence that gnathiid isopods play a role in the transmission of the haemogregarine.

Unlike other sea turtles, the leatherback Dermochelys coriacea forages widely in temperate waters during summer and dives to abyssal depths (>1000 m) where temperatures are low. There is strong anatomical plus limited physiological evidence in favour of at least facultative endothermy. The lipids of leatherbacks exhibit features which are consistent with maintenance of a core temperature above ambient levels when in cool waters. The lipid of flipper adipose tissue freezes at a lower temperature than lipids extracted from the blubber lining carapace and plastron. Lipid freezing points in leatherbacks are lower than for tropical caimans or terrestrial sheep, but higher than for lipids taken from the blubber of a grey seal. Leatherback adipose tissues show levels of unsaturation in neutral lipid fractions intermediate between those of seals and sheep.

Seasonal changes in the assemblage structure of dominant epipelic diatoms were studied along a transect crossing a salt marsh, sandflat, and mudflat of an estuarine intertidal shore at Berrow Flats, Somerset, UK. Seasonal changes in cell numbers displayed different patterns in the salt marsh and sandflat/mudflat. At salt marsh sites highest numbers of individuals were recorded in summer followed by a smaller autumn growth, while in the sandflat lower numbers showed no seasonal pattern. Repeated annual patterns in the succession of taxa were not observed as environmental conditions changed at the study site with time. Measurements of salinity, pH, interstitial water content, air and soil temperature were taken together with the diatom samples. A canonical correspondence analysis was employed to relate seasonal changes in assemblage structure to measured environmental variables. Total percentage variation in the first four axes of the species/site-environmental biplots ranged between 54 and 66°. In winter, sites and species separated most significantly along gradients of salinity and levels of organic matter. In spring and autumn, interstitial water content became a more significant environmental variable. By summer steep gradients in pH, levels of organic matter, and hypersaline conditions separated sites and assemblages into more discrete groups when compared to the more even spread of points in the other seasons. The results indicate that different combinations of environmental variables influence diatom assemblage structure seasonally.

Fieldwork on the estuary of the River Crouch in Essex between 1987 (when the use of TBT antifouling on boats less than 25 m in length was banned) and 1992 revealed marked increases in the species diversity of sublittoral benthic communities in the areas which had originally been most contaminated with TBT. These increases were mirrored by a decrease in the TBT contamination of the sediments. The bivalve molluscs and amphipod crustaceans showed the most marked increases in abundance and diversity.

Whilst investigating the food of young fishes in general (Lebour, 1918–1919–1920) some thousands of young Clupeoids were examined, with the result that by far the larger proportion of post-larvæ were found to be empty. Here and there, however, food was present, and by bringing these records of 1917 to 1919 together, with some from 1920 and 1921, we have a good idea of the food of our three common Clupeoids—Herring, Sprat and Pilchard—in their young stages.

A probable reason for this apparent absence of food in the transparent stages is that the food must be very quickly digested on account of its being so conspicuous; thus it is probably taken only at long intervals and rapidly got rid of. It would follow that under these circumstances we should only occasionally catch the fish when food was inside it.

The observations on the food of the young Herring are perhaps the most interesting of the three on account of the fact that it eats solid food some time before the yolk sac is absorbed, the mouth being open when the fish is hatched, whereas the Sprat and Pilchard, being much less advanced, are only able to feed on outside food much nearer the time when the yolk sac disappears. Unfortunately we have no records of Pilchard food in the very young stages (under 12 mm.), green food remains being found in those of the Sprat before the yolk sac has completely disappeared.

Four species of sea horses (Syngnathidae: Hippocampus) were found in Peninsular Malaysia during a survey conducted between April and August 2001. These were Hippocampus trimaculatus, H. spinosissimus, H. kuda and H. kelloggi. All four species were found in the Straits of Malacca; two species (H. trimaculatus and H. spinosissimus) in the east coast of Peninsular Malaysia in the South China Sea; and three species: H. trimaculatus, H. spinosissimus and H. kuda in the south coast, Straits of Johor. There were habitat and depth separations by species. Hippocampus trimaculatus, which was found throughout the coastal waters of the Peninsular, were reported to inhabit chiefly among gorgonians at approximately 20–40 m depth. The habitat and depth in H. spinosissimus were rather similar to that of H. trimaculatus; but the former species was less widespread in the west coast. Hippocampus kuda was confined to shallow water between 1 to 3 m, and was found in seaweeds and sea grass meadows in a few estuaries; whereas H. kelloggi inhabited gorgonians and sea whips in deep-water below 65 m. Mean standard lengths are given. No sexual size dimorphism was detected in any of the species.

1. 188 Shags and 27 Cormorants, which had been feeding around the shores of Cornwall and whose stomachs contained identifiable food organisms, have been examined.

2. The Shags were found to have been feeding principally upon Sand Eels (Ammodytes spp.), and other non-marketable fishes.

3. The proportion of flatfishes and other economic species which had been devoured by the Shags was negligible.

The red muscle of the thresher-shark myotome is internalized and supplied by a simple rete in connexion with lateral vessels. It is probable that the system enables the fish to be warm-bodied.

INTRODUCTION

Warm-bodied sharks were first described by Carey & Teal (1969); subsequent observations by Carey and his colleagues (Carey et al. 1971) and by Carey (1982) showed that five lamnid species were able to maintain body temperatures 5–10 °C above the ambient water. All of these possess more or less elaborate retia linking a red muscle mass lying internally in the myotomes with the systemic circulation. In cold-bodied sharks, the red muscle lies superficially, just under the skin, and retia are absent. A sixth lamnid species, the big-eye thresher shark (Alopias superciliosus) may be warm-bodied; it has a simple muscle retial system (Carey et al. 1971) which has not been described in detail. The chance capture of a common thresher shark (A. vulpinus) enabled this short description of the retial system in this species.

I trust that I will not be criticized for saying that, in general, the argument between Hensen and Haeckel has been resolved. Hensen (1887, 1895) believed that true spatial and temporal heterogeneity of the plankton could be resolved by careful measurement and analyses of variance. Haeckel (1893) thought these analyses might give more information than the data possessed. Our present understanding of spatial heterogeneity, and its analysis, does not lead us to disagree with either. Investigations carried out by a number of marine ecologists have shown large-scale spatial variations in phytoplankton. Amongst many others, this feature can be seen in studies off the northeast coast of England (Cushing, 1955), in the English Channel and Celtic Sea (Cushing, 1957; Pingree et al. 1976), off Scotland (Adams, Baird & Dunn, 1975,1976) and off the coast of the Netherlands (Gieskes & Kraay, 1975). Nevertheless the statistics of sampling heterogeneous distributions is far from simple, estimates of density for instance can be greatly influenced by the sample size (e.g. Greig-Smith, 1964; Cassie, 1963). Bainbridge (1957) summarized his review by saying that patches occurred on all scales from a few feet to as much as 30 or 40 miles by 120 or 180 miles. Our present understanding of the nature of turbulence in the sea would reduce his few feet to centimetres.

Blooms of the harmful alga Dinophysis acuminata, which produces okadaic acid (OA), are becoming recurrent in Santa Catarina coast, where most of the shellfish marine farms in Brazil are located. We evaluated the impact of D. acuminata blooms on various haemato-immunological parameters and on tissue integrity of cultivated oysters (Crassostrea gigas) and mussels (Perna perna). Animals were sampled during two natural algal blooms, one at Praia Alegre (PA: 2950 cells l−1) and the other at Praia de Zimbros (PZ: 4150 cells l−1). Control animals were sampled at the same sites, 30 days after the end of the bloom. The assayed parameters were: total (THC) and differential (DHC) haemocyte counts, percentage of apoptotic haemocytes (AH), phenoloxidase activity (PO), agglutinating titre (AT) and total protein concentration in haemolymph (PC). Histological analyses were carried out in oysters from PZ. The results showed that some immune parameters were modulated during the toxic blooms, but not in a consistent manner, especially in mussels that accumulated more OA (10×) than oysters. For example, mussel THC decreased significantly (54%) during the bloom at PA, whereas it augmented markedly (64%) at PZ. PO activity was significantly altered by the algal blooms in both bivalve species, while PC increased significantly (66%) only in mussels from PZ bloom. The other parameters (DHC, AH and AT) did not vary in both bivalve species. Histological analyses showed an intense haemocytic infiltration throughout the oyster digestive epithelium, particularly into the stomach lumen during the algal bloom.

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.

The summer of 1954 will long be remembered for lack of sunshine, excess rain and frequent high winds over England and Wales. In the south-west of the region the winds from June onwards until the end of the year were predominantly westerly, often reaching gale force, and the total run of the winds was often above average. During the last week of July there were persistent westerly winds from well out in the Atlantic, often strong and reaching gale force at times, particularly on the 27th and 28th. During the last 4 days the winds were generally from the north-west at Scilly and in southern Ireland. They were variable in strength and direction early during the first week in August, but occasionally blew freshly from the south-west. On the 7th it was often blowing strongly from the west, a gust of 50 knots being recorded at Scilly. It was during this first week in August that the first few specimens of Ianthina janthina (Linnaeus) came ashore, heralding the most extensive strandings of this species on British shores for very many years.