Showing papers in "Journal of the Marine Biological Association of the United Kingdom in 1968"

Vitamin B12 and Marine Ecology. IV. The Kinetics of Uptake, Growth and Inhibition in Monochrysis Lutheri

Abstract: 57Co-labelled vitamin B12 was used to study the kinetics of vitamin B12 limitation in Monochrysis lutheri in continuous and exponentially growing batch cultures and in washed cell suspensions.Specific growth rate in the chemostats was found not to depend directly on medium substrate concentration but on the concentration within the cells (cell quota), obeying a hyperbolic equation of the form

Check-list of British marine algae-third revision

Abstract: The Preliminary Check-list of British Marine Algae (Parke, 1953), with three subsequent lists of additions and corrections (Parke, 1956, 1957, 1959), was superseded by the Revised Check-list of British Marine Algae (Parke & Dixon, 1964). Since the publication of the latter, changes, both taxonomic and systematic, have been sufficiently numerous to warrant the present list incorporating additions, corrections and emendations.The authors take full responsibility for all the changes from the 1964 Check-list. The responsibility for the preparation of the lists of species for each Class in the 1964 Check-list was as follows: (1) Cyanophyceae, H. T. Powell; (2) Rhodophyceae, P. S. Dixon; (3) Cryptophyceae, M. Parke; (4) Dinophyceae, D. Ballantine & M. Parke; (5) Haptophyceae, M. Parke; (6) Chrysophyceae, M. Parke; (7) Craspedophyceae, M. Parke; (8) Xanthophyceae, M. Parke; (9) Phaeophyceae, H. Bladder, G. Russell, P. S. Dixon & M. Parke; (10) Prasinophyceae, M. Parke; (11) Chlorophyceae, E. M. Burrows, P. S. Dixon & M. Parke.The sequences of classes is as in the 1964 Check-list and there have been no changes in the geographical limits used therein (the coasts of Britain and Ireland or in adjacent waters, i.e. the sea area bounded by 47° N. and 63° N., 11° E. and 30° W.). Three classes (Bacillariophyceae, Rhaphidophyceae, Euglenophyceae) are still not represented and the authors would be grateful for records of marine species of these in order to facilitate their inclusion at some time in the future.The compilers welcome any comments on the Revised Check-list (1964) or the present list.

Respiration and nitrogen excretion by some marine zooplankton in relation to their life cycles

Abstract: Rates of respiration and nitrogen excretion have been measured for freshly caught Calanus finmarchicus (Gunnerus), Calanus hyperboreus (Krayer), Metridia longa (Lubbock) and Pareuchaeta norvegica (Boeck), from the Gulf of Maine at all seasons. The dry weight, total (Kjeldahl) nitrogen, and fat were also determined for the same animals. Seasonal variation in weight-corrected respiration and nitrogen excretion followed a similar pattern for all four species, being high in the spring and decreasing gradually through summer and fall to a winter minimum. However, the relative proportions of oxygen utilized to nitrogen excreted were different from season to season for each species. In Calanus spp., O: N ratios by atoms were highest in May, immediately after the spring bloom of phytoplankton, when the animals were rich in fat. With C. hyperboreus the ratio then declined gradually through summer and fall to a low point just before the spring bloom (March and April) when populations contained the least amount of fat; but with C. finmarchicus the ratio fell much more rapidly, remaining near 17 through summer and fall and increasing again with the production of the overwintering generation. In Metridia and Pareuchaeta the O:N ratios did not show as much seasonal variation, although there was a pronounced increase for Metridia just after the spring bloom. Both species usually had higher respiration and excretion rates and lower O:N ratios compared with Calanus spp.

Factors Influencing Shell Shape in the Mussel Mytilus Edulis

Abstract: An attempt is made to explain the great variations in gross shell morphology noted in field populations of Mytilus edulis.In any one mussel population, variation in shell form can be attributed to differences in age, old mussels having proportionately heavier shells where width often exceeds shell height. This is invariably accompanied by down-turned, divergent umbones and varying degrees of incurvature of the ventral shell margin.Variations in the age structure of mussel populations from different habitats can also account for local variability in shell morphology. Localities where the life expectancy of mussels is increased due to absence of predators (especially in the upper shore) reveal a high incidence of old ‘ungulate’ individuals, whereas populations in which the mussel turnover is more rapid show a preponderance of relatively young mussels.Shell morphology is greatly influenced by growth rate and density. These probably exert their effect through physical compression which is maximum in localities of fast growth and high density and least in areas of slow growth and low density. High compression leads to an elongate form whereas low compression results in higher, more triangular shaped shells. Growth rates and densities, even within the same habitat, are, however, exceedingly variable.Since all environmental conditions vary in both time and space, wide variation in shell morphology is to be expected, even in animals from the same locality.Transplantation experiments indicate that variation in shell morphology is essentially phenotypic, older animals being more likely to exhibit a form which is characteristic of their particular habitat. Smaller mussels from widely different habitats show remarkable similarity in shell morphology.

Concentrations of zinc and copper in the tissues of decapod crustaceans

Abstract: Concentrations of zinc and copper have been measured in 18 species of decapod crustaceans, ranging from freshwater to purely marine species. Although the intake of zinc and copper probably varies considerably, the majority of animals contain between 20 and 35 μg/g of both metals. This is probably because the concentrations in the body fluids and tissues are regulated. Reasons for differences between the concentrations of zinc and copper in the individual tissues of different species are discussed and the ways in which regulation is achieved are compared.

Photochemical combustion of organic matter in sea water, for nitrogen, phosphorus and carbon determination

Abstract: A photochemical reactor, using a medium power mercury arc lamp for oxidation of organic matter in sea water, is described. The decomposition of some known compounds in distilled water and in sea water, using a 380 W lamp, was followed. First order kinetics with rate constants in the range 0·2–4·0 h−1 were observed. All the nitrogen compounds tested, including urea and some of its derivatives, were oxidized quantitatively. Breakdown of phosphorus compounds was rapid, but polyphosphate esters yielded polyphosphate ion which was only slowly hydrolysed to reactive orthophosphate. If polyphosphate is to be determined, hydrolysis by heating with acid should follow the irradiation. Some samples of English Channel water contained 0·02-0–05 fig-axom P/1. as organic polyphosphate.

Micro-organisms attached to marine sand grains

Abstract: The distribution, abundance, and types of micro-organisms attached to littoral and sublittoral sand grains have been described. Micro-organisms are present in colonies, ranging from 5 to 150 cells per colony. Many colonies consist of one species. Some colonies are in or surrounded by staining material, others are on flat unstained surfaces. Colonies in staining material often occur in hollows. Large areas of surface between the colonies and staining material are completely bare. Evidence suggests that abrasion may stop micro-organisms colonizing flat or convex surfaces. On grains from the sediment surface, bacteria, blue-green algae (Cyanophyceae), and diatoms (Bacillariaceae) are common. The microbial flora may alter only slightly to depths of 15 cm below the sediment surface, or may change within a few mm. It is sparse towards high water, but differs little between lower littoral and sublittoral sands. The results are discussed in relation to substrate selection by marine invertebrates.

The settlement behaviour of the larvae of Sabellaria alveolata (L.)

Abstract: Using larvae reared from artificial fertilizations in the laboratory, often for several months, many experiments have been made on factors promoting settlement of Sabellaria alveolata (L.). When at last able to metamorphose after many weeks of pelagic development, the larvae of this species crawl actively over any solid surfaces with which they happen to make contact, seeking indicative characters distinctive of their normal adult environment. If these are not found at once the larvae are able to postpone metamorphosis for weeks if necessary, remaining in a developmental state able both to swim and to crawl. If delayed too long in reaching a favourable environment some may metamorphose in the absence of normal environmental stimuli, others often become incapable of metamorphosing normally and do so abnormally, or they may die without metamorphosing.

In situ studies on the cytochemistry and ultrastructure of a symbiotic marine dinoflagellate

Abstract: The intertidal actinian Anemonia sulcata is known to harbour yellow-brown algal symbionts which are similar in appearance to the zooxanthellae of hermatypic, or reef-building, corals and a number of other invertebrate species. The cytochemistry and structural morphology of the zooxanthella has been studied by light and electron microscopy, to help define it taxonomically and to reveal something about its relations with the actinian. These investigations confirm that it is a dinoflagellate and have revealed several structural adaptations which are formed as a result of the peculiar mode of life adopted by this alga. Of significance is the fine structure of the periplast, which may have a considerable bearing upon the type of relationship which can exist between the host and its symbiont. These findings are discussed in terms of other known instances of algal-invertebrate symbiosis.

The bottom fauna of a flatfish nursery ground

Abstract: The macrofauna, defined as infauna retained on a ½ mm sieve, was investigated on a flatfish nursery ground at less than 10 m depth in a Scottish westcoast sea loch during spring and late summer of 1965. The substratum consisted of well-sorted sand of 180–260 μ median diameter, and the infauna had a mean density of 755 individuals and biomass of 1·3 g dry weight/m2 on the beach and 3055 individuals and 3·7 g dry weight in the sublittoral. There was little overall change in the biomass during the period studied, increases in amphipods and some polychaetes being balanced by decreases in other polychaetes, and in Tellina for which no recruitment took place. The distribution of the fauna was studied in detail between high-water mark on the beach and a depth of 10 m below low-water springs. There were 62 species on the beach and 116 on the sublittoral sand. The number increased as the water deepened, the poorest zone being just below low-water mark. Most species showed a distinct zonation. The epifauna of the sand, which was dominated by juvenile stages of plaice and dabs, is briefly described

Rearing herring larvae to metamorphosis and beyond

Abstract: The use of natural plankton and other foods, and of transfer techniques during phases of mortality before metamorphosis, has made it possible for substantial numbers of herring larvae to be reared beyond this stage, thus supplying requirements for experimental work. A survival to and beyond metamorphosis of over 10% of larvae passing the yolk-sac stage (3–4% of hatched larvae) has been obtained.

Experiments on the resynthesis of symbiosis in Convoluta roscoffensis with different flagellate cultures

Abstract: The symbiotic condition of Convoluta roscoffensis has been resynthesized in vitro by feeding new-born colourless larvae with various clones of Platymonas convolutae Parke & Manton available in culture. Greening has also been brought about by feeding larvae with other species distinguishable from the natural symbiont by pyrenoid characters, but subsequent growth of the greened larvae was less and the length of time required for greening greater. The minimum presentation time effective in initiating greening with alien symbionts in 100% of tested larvae was also greater. Cell multiplication of successful symbionts is mitotic, division stages being demonstrated in sections of worms with different types of symbiont. When cultures of potential symbionts were made available competitively in pairs, greening normally involved only one member of a pair, success being apparently determined by the order of relative efficiency demonstrated in the single-culture infections. A chimaeral condition, with two different symbionts present together, was produced and is demonstrated—but only as a temporary phase in an experiment designed to give an alien symbiont a very long start before admitting the real one. In this experiment effective greening with Prasinocladus marinas did not impede prompt entry of Platymonas convolutae when it was supplied, and this was followed by rapid and complete elimination of the alien symbiont. An interpretation of these various findings is discussed in a preliminary way.

Chloroplasts as symbiotic organelles in the digestive gland of Elysia viridis [Gastropoda: opisthobranchia]

Abstract: An investigation into the histochemistry and ultrastructure of the digestive gland of Elysia viridis has revealed the presence of two types of epithelial cells, one of which contains numerous, structurally intact algal chloroplasts. Chromatographic studies indicate that these chloroplasts are derived from the animal's specific food, the alga Codium tomentosum. Following ingestion by the animal these do not appear to be digested or excreted, but accumulate and are maintained in the digestive cells. Autoradiographic studies suggest that they may be of some benefit to the animal as symbiotic organelles. Such a phenomenon may prove to be widespread among related species of Opisthobranchia.

Observations on the population of Scoloplos armiger at Whitstable

Abstract: The population of Scoloplos armiger O. F. Muller at Whitstable was investigated from January 1964 to April 1965. Initially the population density was high, being over 600/m2, but the numbers sharply declined during the summer of 1964 and by the following winter the density had dropped to under 100/m.2 In addition to this decline, the population structure changed, and the overall effect was a marked reduction in the fecundity of the population. The cause of the high mortality in the summer of 1964 is unknown.

Some effects of salinity on the distribution and abundance of Corophium volutator in the Ythan estuary

Abstract: A study of the effects of salinity on the distribution and abundance of the amphipod Corophium volutator (Pallas) on the estuary of the River Ythan, Aberdeenshire, indicates that 2‰ is a critical minimum salinity controlling its distribution. In areas with salinities between 2 and 5‰ C. volutator was present, but in reduced numbers. Breeding occurred only in salinities greater than 7·5‰. In areas with salinity greater than 5‰, the distribution and abundance of C. volutator were controlled by the nature of the substrate; however, in areas with suitable substrates, but where the salinity was below 5‰, the effects of salinity override the effects of the substrate. The annual life-cycle is discussed. The results of this study are compared with those of a recent experimental study.

Some aspects of the development of eggs and larvae of Sabellaria alveolata (L.)

Abstract: The rate of growth of larvae of Sabellaria alveolata (L.) reared in the laboratory varied greatly between different rearings and between individuals of the same age in the same rearing vessel, the temperature throughout being maintained close to 15 °C. The shortest recorded time from fertilization to metamorphosis was 6 weeks, the longest nearly 8 months. Within any one rearing some larvae metamorphosed weeks or months earlier than the last to do so. The larvae were fed on phytoflagellates, especially Isochrysis galbana, and the variations in growth were partially due to differing quantities of food available and to the differing character of the food. The largest larvae obtained, up to 700 μ long, fed in their later stages on an Olisthodiscus sp., alone or with another flagellate. The smallest larvae, only about 400 μ long, ate voraciously large quantities of the coccolith Coccolithus huxleyi. The normal length of larvae fed on Isochrysis alone was about 500 μ.

Seasonal changes in the calcium content of the blood of arctic cod

Abstract: A well-marked seasonal cycle in the total calcium content of the plasma was shown to occur in adult cod, Gadus morhua L., of both sexes: these changes were not found in juvenile, immature cod. The changes in concentration of plasma total calcium appeared to be associated with gonadal maturation, the period of hypercalcaemia coinciding with the maturation cycle and the plasma calcium falling to a resting level again after spawning. Seasonal changes were greatest in the female cod and it is suggested that the raised level of calcium is associated with vitellogenesis in the ripening ovary, probably under the influence of oestrogens. The cycle in the male is not yet fully understood.

The treatment of food by prosobranch veligers

Abstract: A study of nineteen species of monotocardian veligers belonging to eight different superfamilies reveals the uniformity of structure of the alimentary tract up to the time of metamorphosis. Results of feeding experiments with nineteen species of unicellular algae show that there is also uniformity in the functioning of the gut.

Structure, histochemistry and formation of the podocyst and cuticle of Aurelia aurita

Abstract: At the junction between the scyphistoma's scyphopharynx-filament complex and its endoderm is a narrow zone of simple columnar cells. These cells can transform into amoebocytes which collect together and work their way to the aboral end of the polyp, where they secrete a cuticular encasement, thus forming the podocyst.Light and electron microscopy, as well as histochemistry, show the podocyst to be a lamellated tanned chitin-protein complex covering the protoplasmic contents, which have a nucleated outer clear cytoplasmic layer and a yolky central zone which may be liquefied in places.

Biochemical Studies on Marine Zooplankton V. The Composition of the Major Biochemical Fractions in Neomysis Integer

Abstract: The earlier investigations (Raymont, Austin & Linford, 1964, 1966) on the brackish-water, semi-planktonic mysid, Neomysis integer (Leach), dealt with the total protein, lipid and carbohydrate fractions, together with chitin and ash. Results showed that a relatively high protein content (mean 71 % dry weight) was typical of Neomysis; the protein showed very little change throughout the year. Lipid was much lower and more variable (7–15%; mean 13 % dry weight), and carbohydrate was especially low (mean 2.5 % dry weight). Ash and chitin together amounted to some 14 % dry weight (Raymont et al., 1966).

Toxicity of oil-spill removers (‘detergents’) to marine life: an assessment using the intertidal barnacle Elminius modestus

Abstract: The oil-spill removers BP 1002, Gamlen, Slipclean and Dasic have been tested for toxicity using the barnacle Elminius modestus Darwin. All four substances were more toxic than the laboratory detergent Teepol-L, and Kuwait crude oil. BP 1002 was the most toxic of the oil-spill removers, and Dasic the least, but all were poisonous at concentrations between 2 and 10 ppm.

Aspects of Osmotic and Ionic Regulation in Corophium Volutator (Pallas)

Abstract: Experiments have been made to elucidate the problem of hyperosmotic regulation in the mud-dwelling euryhaline amphipod, Corophium volutator. The animal produced urine hypo-osmotic to the blood when acclimatized to low salinities, and isosmotic urine at salinities above 20%. The restricted permeable areas of the cuticle have been localized by silver staining. Over a range of salinities from 1 to 35 % C. volutator was found to maintain Na+, K-−, Ca2+, Cl-−, more concentrated than the medium, and Mg2~ less concentrated. The importance of these mechanisms in assisting hyperosmotic regulation is discussed.

Seasonal variations in the effect of temperature on the respiration of certain intertidal algae

Abstract: The intertidal algae Enteromorpha, Ulva, Fucus, Porphyra, Chondrus and Griffithsia are subjected to wide semi-diurnal fluctuations in temperature during the summer months. Measurements of the rate of respiration of such algae in the dark at a wide variety of temperatures have shown that during the summer the curve relating respiration to temperature ( R. T curve) has a relatively shallow slope of Q 10 R. T curves which have a shallow slope in regions approximating to the temperature of the shore at the time of collection. Thus the respiration of such intertidal algae is relatively unaffected by temperature fluctuation within the normal environmental range. Further, the form of the R. T curve is not a fixed phenomenon which is characteristic of a particular species of alga, but appears to be modifiable in such a way that the shallow region of the R. T curve is appropriate to the temperatures prevailing in the habitat. In this way the effects of temperature fluctuation upon respiration are minimized.

Studies on the growth of Phaeodactylum tricornutum III. The effect of iron on growth

Abstract: The iron nutrition of Phaeodactylum tricornutum (Bohlin) has been studied, and the limitation of growth because of iron deficiency demonstrated. Evidence is presented suggesting the ability of the organism to utilize paniculate iron and to adjust its utilization of iron in the presence of a continuing deficiency. One effect of lack of iron is a reduction in the degree of pigmentation and the ability of added iron to restore the pigmentation. Figures are presented showing the iron content per cell, and a comparison with other organisms suggests that the brackishwater P. tricornutum may be atypical when compared with coastal and oceanic members of the marine phytoplankton.

Long-term effects of low concentrations of an oil-spill remover (‘detergent’): studies with the larvae of Sabellaria spinulosa

Abstract: The ‘detergent’ BP 1002 at concentrations of 1 ppm was detected immediately by the larvae of Sabellaria spinulosa which were intensely irritated by it. In loosely covered vessels, allowing the solvent fraction to evaporate, larvae seemed at first to recover but died several weeks later, the control larvae remaining active and normal. The surfactant and stabilizer fractions at concentrations of 2·5 ppm killed the larvae within a day or two.

Studies on the Growth of Phaeodactylum Tricornutum IV. Comparison of Different Isolates

Abstract: IntroductionThe diatom Phaeodactylum tricornutum Bohlin has been used in numerous experiments on the physiology and biochemistry of diatoms since the publication of the first paper involving this organism by Allen & Nelson (1910). The taxonomic position of the organism has been dealt with by Lewin (1958), who also lists the papers which she considers to have involved the use of P. tricornutum. The present study reports the results obtained from a comparison of different isolates of this organism.