Showing papers in "Journal of the Marine Biological Association of the United Kingdom in 1965"
TL;DR: The morphology and microanatomy of two species of Platymonas have been investigated and certain stages of cell division studied as mentioned in this paper, and anatomical features closely resemble those recently described for the motile phase of Prasinocladus except for characteristic differences in pyrenoid structure.
Abstract: The morphology and microanatomy of two species of Platymonas have been investigated and certain stages of cell division studied. The anatomical features closely resemble those recently described for the motile phase of Prasinocladus except for characteristic differences in pyrenoid structure (cf. Parke & Manton, 1965). The flagella ofPlatymonas are indistinguishable from those of Prasinocladus, being covered with two layers of scales beneath a layer of structureless mucus which obscures their presence except in sections. Caducous hairs resembling those ofPrasinocladus and related genera are also borne on the flagella.
132 citations
TL;DR: In this article, Nitrogen excretion by Calanus finmarchicus (Gunnerus) and C. helgolandicus Claus collected at Millport and Plymouth has been measured under various experimental conditions.
Abstract: Nitrogen excretion by Calanus finmarchicus (Gunnerus) and C. helgolandicus Claus collected at Millport and Plymouth has been measured under various experimental conditions. Adult females feeding on Brachiomonas submarina, Cricosphaera elongata and Skeletonema costatum at cell concentrations corresponding to the mean annual level of particulate nitrogen in Plymouth Sound excrete 12·4, 9·0 and 6·4 μg N/mg dry body weight/day respectively. When the concentration of food is raised, as might occur during a spring outburst of phytoplankton, there is an increase in the quantity of nitrogen excreted. On the other hand, nitrogen excretion rapidly diminishes in the absence of food.
110 citations
TL;DR: The details of the periplast on cell body and flagella, the presence of stellate scales as well as plate-scales on both types of surface, and of a characteristic fibrous ‘root’ joining the flagellar bases to the plastid surface are found.
Abstract: A light and electron microscopical study has been carried out on the morphology and microanatomy of two marine species of Heteromastix and less completely on two freshwater samples from the same genus, one only of which is named; this one is, however, important as the type species of the genus ( H. angulata Korsh.). Agreement in salient features indicates that Bipedinomonas N. Carter and Anisomonas Butcher, under which the marine species were previously described, should be discarded as later synonyms of Heteromastix Korsh. Apart from the nomenclatural clarification the most important new findings concern the details of the periplast on cell body and flagella, the presence of stellate scales as well as plate-scales on both types of surface, the presence within the body of a starch shell not giving the normal colour reaction with iodine, and of a characteristic fibrous ‘root’ joining the flagellar bases to the plastid surface. A major finding of electron microscopical interest is the clarity with which the formation of scales and of flagellar hairs has been traced to the Golgi cisternae. These observations are an important addition to previous knowledge concerning genera of related green flagellates possibly referable to the class Prasinophyceae.
86 citations
TL;DR: The type species of Prasinocladus has been re-investigated in cultured material from the Devon coast and studied electron-microscopically by whole mounts and by sections as mentioned in this paper.
Abstract: The type species of Prasinocladus has been re-investigated in cultured material from the Devon coast and studied electron-microscopically by whole mounts and by sections. Salient findings include: the presence of two layers of scales together with characteristic hairs on all four flagella; the arrangement of the flagellar bases in a row, and of characteristic flagellar ‘roots’; the presence of an unusual condition of the pyrenoid with respect to the nucleus; and the structure and behaviour of the theca as different from that of an ordinary cell wall. It is concluded that the genus could appropriately serve as the type of a group to include all known genera and species of monads containing chlorophyll b that possess scaly flagella, but no recommendations are made as to whether the name Prasinophyceae (Christensen, 1962) should be restricted to these or be permitted to cover other known green flagellates lacking scales on their flagella. This investigation is continuing.
82 citations
TL;DR: The vertical migration pattern of the Euglena obtusa on the River Avon at Bristol, England has been studied in the laboratory in constant illumination, constant temperature, and away from the influence of the tide for nearly one month as discussed by the authors.
Abstract: During daytime low tides on the River Avon at Bristol, England, the exposed river banks become a deep green colour owing to the presence of enormous numbers of Euglena obtusa which emerge out of the black mud. Cell densities on the surface surpass 105 cells/cm2. Before the tide returns to cover the area, the cells re-burrow back into the mud and remain there during high tide and throughout the night.The cells can be prevented from emerging on to the surface mud at low tide by artificially darkening the area with an opaque covering just as the tide recedes. Cells which are already on the surface can be made to re-burrow by similarly placing them in darkness.The vertical-migration rhythm will persist in the laboratory in constant illumi-nation, constant temperature, and away from the influence of the tide, for nearly one month. In these conditions the rhythm is diurnal, rather than tidal. The rhythm will not persist in constant darkness.Because of the excessive turbidity of Avon water, each high tide imposes a period of darkness on the surface mud. It is thought that these dark periods transform the fundamental diurnal rhythm into one of tidal frequency.Various intensities of constant illumination alter the form and amplitude of the rhythm, but not the period. The stable nature of the period, under different light intensities, is thought to be due to a unique, self-stabilizing feature inherent in this type of rhythm.The rhythm is inhibited at 2° C. Between 5° and 15° C, the period of the rhythm is virtually unaltered; it remains approximately 24 h in length.
81 citations
TL;DR: In this paper, a linear relationship between the percentage fat and the percentage water contents for whole herring minus gonads and gut content was derived from nearly 900 individual herring sampled in the North Shields, Whitby and East Anglian fisheries during the period 1956-60.
Abstract: Data from nearly 900 individual herring sampled in the North Shields, Whitby and East Anglian fisheries during the period 1956–60 demonstrate a linear relationship between the percentage fat and the percentage water contents for whole herring minus gonads and gut content, and the fat/water line derived from the data is described.
73 citations
TL;DR: In this article, it was shown that the fish reflects the fraction of the light striking the platelets which is sufficient to match the background against which the fish is seen, and that the reflecting platelets on the curved dorsum have the property of reflecting green light well if it falls obliquely on them but reflecting it poorly when it strikes them at angles close to normal incidence.
Abstract: The orientations of the reflecting layers in the external surfaces of the herring have been found both by light-measurements on the fresh fish and by histological studies on preserved specimens.The reflecting platelets which lie under the scales are orientated, with respect to the surface of the fish, in a similar way to the platelets found in the bleak and described earlier by Demon & Nicol (1965). However, on the curved dorsum of the fish, although the reflecting platelets are much more perpendicular to the sea surface than the scales on which they lie, these platelets are still inclined some 20° to the perpendicular. It is shown that, in this region, the fish reflects the fraction of the light striking the platelets which is sufficient to match the background against which the fish is seen. The platelets on the curved dorsum have the property of reflecting green light well if it falls obliquely on them but reflecting it poorly when it strikes them at angles close to normal incidence. On the broad flank of the herring the scales have reflecting platelets under most of their surfaces, and the individual scale has several distinctly coloured regions. When we look at any particular region of the flank of an intact fish we are always looking at several overlapping layers differing greatly from one another in their spectral reflecting properties.It is the combination of the reflexions of several layers which gives the very bright silvery reflexions of the intact fish. A system of overlapping scales of this kind is needed even to reflect one waveband of light well over a wide range of angles of incidence.
69 citations
TL;DR: The chitin from pogonophore tubes is shown to be essentially the same as that from the pen of the squid Loligo and is classified as β-chitin, which is of interest in defining the systematic position of the Pogonophora as well as in reaching an understanding of the functions of the protective tube.
Abstract: The chitin from pogonophore tubes is shown to be essentially the same as that from the pen of the squid Loligo and is classified as β-chitin (as are the known chitins in annelids). However, certain important differences in detail are seen when comparing X-ray diffraction photographs and infra-red absorption spectra of the chitin from the two sources. These matters are of interest in defining the systematic position of the Pogonophora as well as in reaching an understanding of the functions of the protective tube.
66 citations
TL;DR: An apparatus for sampling the fauna of the uppermost 10 cm of the sea is described in this article, which is designed to fish at speeds of 5-6 knots in undisturbed water to one side of a ship.
Abstract: An apparatus for sampling the fauna of the uppermost 10 cm of the sea is described. The net is designed to fish at speeds of 5–6 knots in undisturbed water to one side of a ship. A preliminary account is given of the catches made with the net in the Indian Ocean.
58 citations
TL;DR: An electrophoretic study of whole blood samples revealed the presence of haemocyanin and of various other proteins in the blood of fifteen species of marine and terrestrial amphipods and isopods, and the slow protein fractions appear to play a number of roles in the species investigated.
Abstract: An electrophoretic study of whole blood samples revealed the presence of haemocyanin and of various other proteins in the blood of fifteen species of marine and terrestrial amphipods and isopods. The amount of haemocyanin per 1 mm 3 of blood is independent of body weight over a range from 10 mg to 1 kg. Under laboratory conditions and during starvation the haemocyanin level of the blood is lowered as compared with freshly caught specimens. No relationship between moulting stage and haemocyanin content could be established in three oniscoid isopods, representing Ligia, Oniscus , and Porcellio . In some species the densities of both haemocyanin and ‘slow proteins’ (i.e. proteins between starting line and haemocyanin) seem to vary in more or less the same direction, over at least part of the total range of variability. In the offshore Conilera , however, an indirect relationship seems to exist between these two protein fractions. This is reminiscent of the situation in Maia squinado described by Zuckerkandl (1960). The slow protein fractions appear to play a number of roles in the species investigated. In Conilera they consist of various copper proteids (perhaps concerned with the synthesis of haemocyanin?), while in intertidal amphipods and some isopods they carry chromophilic groups that may be of importance in mechanisms of colour change. The colour of the blood of a given specimen of Orchestia gammarella and Marinogammarus marinus depends on the amount of the faster moving, blue chromoproteid present in the blood. These chromoproteids are considered to be carotenoproteids.
57 citations
TL;DR: Extracellular carbohydrate production was found to be greatest during the early and later stages in growth and dropped to a minimum during the mid-growth phase and it is suggested that the production of most of the extracellular carbohydrates is due to the passive release of organic matter from dead or dying cells.
Abstract: The production of extracellular carbohydrate has been studied in Isochrysis galbana and Prymnesium parvum in axenic culture. Increased extracellular production of carbohydrate occurred at reduced and increased salinity, low light intensity and under conditions of nitrogen starvation in Isochrysis, and in some cases appeared to be associated with the sedimentation of the cells from stagnant culture. Extracellular carbohydrate production was found to be greatest during the early and later stages in growth and dropped to a minimum during the mid-growth phase. Experiments indicated that the cells were not being damaged during harvesting of the cultures. A close similarity was found between the monosaccharide components of the intra- and extracellular carbohydrate after acid hydrolysis; both contained glucose, galactose, arabinose, xylose and ribose. It is suggested that the production of most of the extracellular carbohydrate is due to the passive release of organic matter from dead or dying cells.
TL;DR: The biochemical composition of the eggs of Balanus balanoides and B. balanus has been determined during development as discussed by the authors, showing that the pigment is largely a chromolipid; during the early stages of development this increases, but is subsequently lost.
Abstract: The biochemical composition–water, glucose, soluble and insoluble glycogen, protein and non-protein nitrogen, total lipid–of the eggs of Balanus balanoides and B. balanus has been determined during development.Preliminary analyses of the pigment content are reported.The changes in both species are similar; but they take place more rapidly in B. balanus with its shorter period of embryonic development.During development there is a net loss of all fractions; small increases of glucose and soluble nitrogen are, however, found at certain stages.The pigment is largely a chromolipid; during the early stages of development this increases, but is subsequently lost; astaxanthin is also present. The visual appearance is a poor guide to pigment content.The oxygen uptake of the eggs has been measured.There is a discrepancy between the oxygen uptake measured directly and that required to oxidize the substrate lost; the causes of this are discussed.The results are discussed relative to the habitats of the species.
TL;DR: Two phases, cyst and motile, of three species of Halosphaera (Prasinophyceae), H. viridis Schrn.
Abstract: Two phases, cyst and motile, of three species of Halosphaera (Prasinophyceae), H. viridis Schrn., H. minor Ostenf. and H. russellii Parke, sp.nov., are described and the distinguishing characters tabulated. The stages in development of the two phases are detailed and a possible periodicity in their production is suggested. Only the motile phase can persist as an independent form reproducing asexually by fission. Sexuality is not recorded for the genus nor can the reported production of aplanospores be substantiated. The supposed ‘heterokont motile phase of Halosphaera’ of Pascher, who placed the genus in the Xanthophyceae, is believed to be a colourless phagotrophic flagellate parasitizing the cyst phase. All cyst phases, with plain or punctate walls, resembling those of Halosphaera in structure, do not necessarily belong to this genus. The study of living material is therefore essential.
TL;DR: Measurements of the light transmitted by silvery scales of the bleak show that they reflect light strongly when this falls obliquely on the crystals which they contain and that they are most transparent to light which strikes the scales in a direction perpendicular to the reflecting planes of the crystals.
Abstract: The problem of how a fish can make itself invisible in the natural light-conditions in an aquatic environment is discussed with particular reference to the silvery surfaces of fish.In fish which we have examined, the silvery surfaces are of two types: (1) an argenteum which consists of long thin crystals of guanine whose reflecting surfaces are approximately parallel with the surface of the fish; (2) layers of guanine crystals lying either on the inner surfaces of the scales or in the subdermis—these crystals are not, in general, orientated with their reflecting surfaces parallel with the surfaces of the fish, and are much broader than those of the argenteum.Methods are described by which the orientation of the crystal planes with respect to the planes of the scales on which they lie can be determined.The orientation of the crystals of type 2 in different parts of the body is described for the horse mackerel, Trachurus trachurus (L.), and for the bleak, Alburnus alburnus (L.).For the bleak it is shown that although the planes of the crystals are often very much inclined with respect to the planes of the scales, the long axes of the crystals are always approximately parallel with the planes of scales. The inclination of the crystals, therefore, is away from the scales across their short axes.Measurements of the light transmitted by silvery scales of the bleak show that they reflect light strongly when this falls obliquely on the crystals which they contain and that they are most transparent to light which strikes the scales in a direction perpendicular to the reflecting planes of the crystals.
TL;DR: The feeding mechanisms of Ophiocomina nigra are re-examined and a new mechanism, the mucus-net method, is described for the first time, which is essentially a method of suspension feeding in which seston is trapped in a net of mucous threads between the arm spines.
Abstract: The feeding mechanisms of Ophiocomina nigra have been re-examined. A new mechanism, the mucus-net method, is described for the first time. This is essentially a method of suspension feeding in which seston is trapped in a net of mucous threads between the arm spines. The entangled material is formed into boluses by simultaneous activities of ciliary currents and the tube-feet and is transported to the mouth by the tube-feet.
TL;DR: In moving water all species show practically continuous activity, the velocity of the flow needed to produce this response varying according to the species, habitat, and previous history of the specimen.
Abstract: Records of cirral activity have been made over periods of 24–48 h for individual specimens of eight species of barnacles from three different localities. The effects of movement, gas content, and hydrogen-ion concentration of the water have been studied.In still water most species eventually settle down to a more or less steady rhythm (activity rhythm) of short bursts of cirral beating interspersed with inactive periods. Two exceptions are the surf- or current-loving species Balanus cariosus and Tetraclita squamosa which remain inactive or eventually cease activity. In moving water all species show practically continuous activity, the velocity of the flow needed to produce this response varying according to the species, habitat, and previous history of the specimen. Increased oxygen content has less effect on activity than other factors studied, but eventually appears to reduce activity. A gradual reduction in oxygen content first leads to increased activity and then signs of distress attributable to anoxia.
TL;DR: Inactive Mn concentrations have been measured in lobster tissues and up to 30 μg/g are found as discussed by the authors, and the carapace Mn concentration is variable and it may be a passive rather than an active process and there is no evidence that the slow absorption of Mn from solution in sea water across the gills can in any way be controlled.
Abstract: Inactive Mn concentrations have been measured in lobster tissues. In the internal tissues of fresh animals, muscle contains 0.5–1.1 μg/g wet tissue, hepatopancreas contains 4.1–5.7 μg/g, excretory organs contain 2–5.5 μg/g and the blood contains 1.4–3.8 μg/g. Gill Mn concentrations are very variable and up to 30 μg/g are found. About 98 % of the Mn in the body lies in the calcified exoskeleton. Concentrations in the carapace are variable and are of the order of 100–300 μg/g of wet tissue. Possible ways in which the body Mn content may be controlled have been studied.Manganese is lost from the blood during starvation and is absorbed so slowly from solution in sea water that normally an appreciable amount of the body Mn must be absorbed from food. Absorption from the stomach takes place via the hepatopancreas and the amount absorbed appears to be proportional to the Mn concentration of the stomach fluid. Similarly, there is no evidence that the slow absorption of Mn from solution in sea water across the gills can in any way be controlled and it may be a passive rather than an active process.
TL;DR: A system of nerves (called for short NSV system) described previously in Eledone cirrosa, whose only task appears to be the formation of a fine neuropile in the vena cava, is present also in Sepia officinalis and shows certain special features.
Abstract: A system of nerves (called for short NSV system), described previously in Eledone cirrosa , whose only task appears to be the formation of a fine neuropile in the vena cava, is present also in Sepia officinalis It has a similar disposition to that in Eledone but shows certain special features. It is composed of neurons the cell bodies of which are located in a layer (NSV layer) of the visceral lobe of the brain and in the paired ganglionic trunks, termed the lateral and medial NSV trunks, which emerge from the visceral lobe with the posterior infundibular and visceral nerves respectively. After accompanying these nerves for some distance these trunks take an independent course and give off some tapering branches ending blindly in the loose connective tissue.
TL;DR: In this article, a thin-layer chromatography has been used for the rapid separation of microgram amounts of pigments of marine phytoplankton, both from cultures and from the sea.
Abstract: Thin-layer chromatography has been used for the rapid separation of microgram amounts of pigments of marine phytoplankton, both from cultures and from the sea. The separation is carried out on plates coated with silica gel; the chromatogram is developed with a solvent consisting of petroleum ether (b.p. 60–80°), ethyl acetate and diethylamine in the ratio 58:30:12 by volume. The separated individual pigments may be eluted from the plate and characterized by their absorption spectra. The pigments of the following phytoplankton have been examined: Dunaliella primolecta, Phaeodactylum tricornutum, Isochrysis galbana, Dicrateria inornata, Coccolithus huxleyi, and Peridinium trochoidium.IntroductionA knowledge of the component pigments of phytoplankton is of value in the systematic classification of these organisms and in the study of the mechanism of photosynthesis. Very little is known about the amounts of the lesser phyto-plankton pigments associated with the natural phytoplankton crop in the sea, but a considerable amount of work has been carried out on the measurement of chlorophylls a, b and c and of carotenoids for the estimation of the plant bio-mass in the sea. These determinations are usually carried out by modifications of the poly-chromatic spectrophotometric method originally described by Richards with Thompson (1952) and modified by Creitz & Richards (1955) (see also Parsons & Strickland, 1963). While these procedures give a satisfactory measure of chlorophylls a and b, their precision for chlorophyll c and carotenoids is poor; furthermore, no resolution of carotenes from xanthophylls can be attained; nor can any indication of the presence of unusual pigments be obtained.
TL;DR: Several distinct features such as the spines covering the valves, the ridged valve margin and special flagella pore structures suggest that it may be necessary to create a new genus of Exuviaella.
Abstract: The structure of the thecae, as seen in the electron microscope, are described for two species of Prorocentrum and five of Exuviaella. For the first time it is possible to distinguish between true pores and the spines and thin areas of wall which have previously been described as pores or poroids. Several distinct features such as the spines covering the valves, the ridged valve margin and special flagella pore structures which are found in only two of the Exuviaella species suggest that it may be necessary to create a new genus.
TL;DR: Detailed examination of the distribution of colonies indicated that the planulae probably possess clearly defined patterns of behaviour which assists them in locating substrates suitable for colonization, and the possible significance of these pattern of behaviour in the substrate selection and distribution of the species is discussed.
Abstract: The preoccupation of many workers in recent years with the detailed analysis of the settlement behaviour of the larvae of numerous sedentary invertebrates has contributed significantly to our understanding of the various factors influencing the secondary orientation reactions of animals as formulated by Fraenkel & Gunn. Investigations with the planula larvae of hydroids along these lines has hitherto been largely ignored. The intertidal hydroid Clava squamata Muller has a distribution restricted to the larger fucoids in the littoral zone and during the summer months liberates its planulae in large numbers.Detailed examination of the distribution of colonies indicated that the planulae probably possess clearly defined patterns of behaviour which assists them in locating substrates suitable for colonization. The planulae which are released in response to light are normally found to be photopositive on inert surfaces and to settle photopositively. On Ascophyllum, however, the normal substrate in nature, the older larvae are photonegative. The crawling activity of the planulae is considerably influenced by the texture and contour of surfaces. On rough and pitted surfaces activity is considerably reduced indicating a thigmokinetic response of the larvae. Water currents influence behaviour, planulae orientating positively to the direction of flow. The possible significance of these patterns of behaviour in the substrate selection and distribution of the species is discussed.
TL;DR: There was evidence that the gadoids exercised choice of food from that potentially available from the four primary food sources in each habitat; but if their favourite food was scarce or lacking, they would take substitute food by exploiting sources otherwise normally neglected.
Abstract: The food and feeding habits, and general biology of the commoner gadoids in Manx waters have been studied. During the pelagic phase the diet of the gadoids showed a great similarity, consisting mainly of various abundant calanoid copepods. The larger pelagic post-larvae supplemented this basic diet with the inclusion of euphausiid ‘furcilia’ larvae and (in whiting) the amphipod Hyperia. Whiting, cod and pout were often found associated with medusae: the whiting, 21–53 nun long, were taken in large numbers, and their diet was found to be modified as a result of this association.Young gadoids in a shallow sandy bay showed a great similarity in their basic diets, which typically consisted of various small, swarming mysids, amphipods and isopods. This habitat was a nursery area for many of the gadoids.The larger fishes fell into two groups: (i) those that were characteristically feeders on the infauna and large, slow-moving epifauna; such fish being provided with stout barbels, well equipped with taste-buds, e.g. cod; (ii) those that feed largely, on the smaller active epifauna and nektonic prey, and possessed no, or only rudimentary, barbels, e.g. whiting.The larger gadoids showed a concentration after spawning on a shallow, submarine shelf (the Warts Bank) to the south of the Isle of Man. Here the spent fish fed on an abundant and localized food, sand eels. The gadoids were found in this habitat from March to September, and were the object of a local fishery.There was evidence that the gadoids exercised choice of food from that potentially available from the four primary food sources in each habitat; but if their favourite food was scarce or lacking, they would take substitute food by exploiting sources otherwise normally neglected.
TL;DR: In North Wales settlement and metamorphosis of Balanus balanoides occur in May and the animals breed for the first time in the following November.
Abstract: 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.
TL;DR: Praunus inermis (Rathke) breeds at all times of the year in the Clyde, the pro-portion of breeding females being minimal in January and maximal in August, and the number of young varies seasonally, being about 30–40 in May/June and 10 during the period November to January.
Abstract: Praunus inermis (Rathke) breeds at all times of the year in the Clyde, the pro-portion of breeding females being minimal in January and maximal in August. The progeny produced by the winter stock during the period March to July are known as the summer generation, the eldest members of which commence breeding in July/August, and the new winter stock is formed in the autumn from the surviving members of this generation and their progeny. The number of young carried in the marsupium varies seasonally, being about 30–40 in May/June and 10 during the period November to January. Larger females tend to carry more young than smaller females. Comparisons are made between the population in the Clyde and those at Port Erin, Isle of Man, and at Nyborg Fjord, Denmark.
TL;DR: In this paper, a method was described for measuring, for various angles of incidence, the polarization produced by reflexions from natural surfaces, which was tested by measurements on matallic surfaces of known properties and then used to study reflexions of the silvery gill cover of the bleak Alburnus alburnus (L.).
Abstract: A method is described for measuring, for various angles of incidence, the polarization produced by reflexions from natural surfaces.This method was tested by measurements on matallic surfaces of known properties and then used to study reflexions from the silvery gill cover of the bleak Alburnus alburnus (L.).Althouth the reflecting surfaces of the gill cover are crystals of a dielectric guanine, there is no polarizing angle, and the reflecting properties of the gill cover resemble those of a sputtered aluminium mirrorThe biological significance of these results is briefly discussed.
TL;DR: The distributions of four species of larval Ammodytidae in the Southern North Sea are described, with evidence for a spawning area some distance to the west of the Dover Strait.
Abstract: The distributions of four species of larval Ammodytidae in the Southern North Sea are described. Two separate broods of Ammodytes lancea larvae were found, in spring and autumn. The spring larvae occurred in the areas of the Thames and Wash, and the autumn type mainly off the French and Dutch coasts.A description of these larvae is given. Larvae of Gymnamtnodytes semisquamatus were found in the Southern Bight area and in several areas off the Humber. Few larvae of Ammodytes lanceolatus were taken: they occurred in the Southern Bight and Dowsing areas. A. marinus larvae were found in two areas off the Humber and in the Southern Bight. There is evidence for a spawning area some distance to the west of the Dover Strait.