Showing papers in "Journal of the Marine Biological Association of the United Kingdom in 1974"

The nutrient status of algal cells in continuous culture

Abstract: Chemostats were used to study the relation between growth rate, the rate of nutrient uptake and internal and external nutrient concentrations of two nutrients simultaneously. (Monochrysis lutheri: phosphorus and vitamin B12.)Growth rate and internal concentrations of both limiting and excess nutrients are related by simple rectangular hyperbolas.Control was shown to follow a threshold rather than multiplicative pattern; that is, non-limiting nutrients exert no control at all over the pattern of growth. The limiting nutrient was the one that showed the smallest cell quota: subsistence quota ratio.Monochrysis populations exhibited two modes of growth. ‘Slow adapted cells’ differed from ‘fast adapted cells’ in the values of the constants for the above relation.Uptake of both limiting and non-limiting nutrients was found to be controlled by internal as well as external substrate concentrations. There was thus a limit to luxury consumption of one nutrient when growth was limited by another.The mathematical model formulated for growth in a chemostat (equations (23)–(29)) allowed prediction of external and internal substrate concentrations and rates of uptake of two nutrients and of biomass, given only the input concentrations of the two nutrients and the dilution rate. This model should apply equally well to growth in batch cultures; its possible application to natural populations was discussed.

Incubation in British Decapod Crustacea, and the Effects of Temperature on the Rate and Success of Embryonic Development

Abstract: Twenty-one species of female decapod Crustacea with gravid ovaries were collected from the field and spawned naturally in the laboratory. Newly spawned eggs and in­ cubating females were kept at temperatures between 3 °C and 24 °C constant at 3 °C increments until the eggs hatched after completing their embryonic development. Observations on developing eggs confirmed that in decapods which hatch at a zoea stage, the pre-zoeal cuticle is associated with the metanauplius stage relegated to em­ bryonic life, rather than to the preceding nauplius. During embryonic development, the rate of egg volume increase (elsewhere attributed to osmotic uptake of water) is con­ sidered slower in the eggs of species with a long development period than in those which develop rapidly. In all species here studied the rate of increase of egg volume accelerated during development, especially in the latter stages. The rate of yolk metabolism varies from species to species according to the time taken for egg development, but in all species it was slower during early development than during the last few days before hatching. In very early development (around gastrulation), the eggs of four unrelated species were found to possess a form of diapause which could not be shortened signifi­ cantly by raising the water temperature. It is suggested that diapause has evolved in certain species as a response to the availability of food in the plankton and to enhance larval survival. The development times from spawning to hatching of eggs (D), are described as functions of temperature (T) by BSlehradek's temperature equation D= a (T—a)b, using the calculated value of b = —2-3 applying to 12 species with continuous develop­ ment, and for which adequate experimental data were obtained. The small range in the computed values of a. (a = o-o to a = —4-7) is consistent with all species having been collected from the same temperature regime, but a good fit could still have been obtained for all curves had the value of a been set equal to zero. From limited data, it is possible to suggest that increasing egg size slows down the rate of development and increases the value of a between closely related species only. BSlehradek's function applied to species with an inherent diapause only after this stage had been passed. Experiments with Macropipus depurator (L.) showed that a threefold decrease in egg development time can occur naturally in successive batches of eggs incubated during the early spring to mid-summer breeding season of a single species in the one locality. However, a rapid rise in water temperature of as little as 3 °C can disrupt the natural sequence in the spawning and incubation of successive egg batches, and also reduce fecundity by more than 90%. Small eggs were able to survive in higher temperatures than larger, more yolky eggs, and at temperatures of 3 °C and below, the tolerance limits were probably determined by excessive slowing down of development rather than by any directly harmful effect. Larval viability is reduced when the entire period of egg development has taken place in temperatures outside the normal spring and summer range (8 °C to 16 °C), especially among species with large eggs incubated at higher than normal temperatures.

A New Index Measuring Evenness

Abstract: The use of diversity and evenness indices is well established in recent ecological literature. Many indices have been proposed, to such an extent that the choice of a suitable index became somewhat of a problem. Recently, however, Hill (1973) introduced a unifying notation where diversity numbers are denned in relation to Renyi's definition of a generalized entropy. Hill showed that his diversity numbers Na of the oth, 1st and 2nd order coincide with three important diversity measures which have been frequently used, No = S, N1 = eH and N2 = 1/SI, where S is the number of species, H is the shannon-Wiener information function –Σpi In pi and SI is Simpson's index . According to this notation, evenness should be calculated by dividing two of Hill's diversity numbers, e.g. N2/N1 = eH/S. This index was proposed by Sheldon (1969), but its use in ecological literature has been negligible. The most commonly used evenness index has been the one proposed by Pielou (1966), e = H/Hmax, with Hmax = lnS. Contrary to Hill's (1973) statement, it shares with Hill's continuum of evenness measures the property of remaining constant when the number of individuals of all species is multiplied with a constant factor. Intuitively, this seems to be a necessary property of an evenness index.

An Estimate of Benthic Macrofaunal Production in the Offshore Mud of the Northumberland Coast

Abstract: This paper reports the first phase of an extended exercise in benthic ecology, involving both long- and short-term aims. The short-term aim is to examine the benthic fauna of representative substrate types for a period of a year and to compute the net secondary production of the infaunal macrofauna in terms of ash-free dry weight per square metre per annum. The intention is to identify from among the bulk of species those animals which have the highest productive capacity, to rank these in order of productive importance, and finally to give our best estimate of the production of the animal assemblage as a whole.

The Hydrolysis of Ammonium Ions in Sea Water-a Theoretical Study

Abstract: A number of procedures are now available for calculating the effects of ionic inter-actions on the behaviour of solutions as complex as sea water (Whitfield, 1973 a). These procedures are able to give a good account of the properties of the major electrolyte components (Leyendekkers, 1973 a; Robinson & Wood, 1972; Whitfield, 19736) and of the colligative properties of sea water (Robinson & Wood, 1972; Whitfield, 1973 c, d). However, greatest interest centres around the possibility of predicting the effects of these major components on the multitude of ionic equilibria that influence the properties of the less abundant constituents that are of greater biological and geological importance. It is here that the newer approaches to marine chemistry are weakest because suitable thermodynamic data are lacking. One system of practical importance that can be studied using a variety of theoretical approaches is the acid ionization of ammonium ions represented by the equation The toxicity of ammonium salts to freshwater life has been shown to be strongly dependent on the pH in a manner that is consistent with un-ionized ammonia (NH3) being the most lethal fraction (see, for example, Wuhrmann & Woker, 1948; Downing & Merkens, 1955; Lloyd & Herbert, i960; Hemens, 1966; and Brown, 1968). These papers and many others have been thoroughly reviewed (EIFAC Technical Paper no. 11, 1970, Kemp, Abrams & Overbeck, 1971). The free base (NH3) has a relatively high lipid solubility because it carries no charge and is therefore able to diffuse quite readily across cell membranes (Fromm & Gillette, 1968).

Effects of Starvation on Structure and Function in the Digestive Gland of the Mussel ( Mytilus Edulis L.)

Abstract: During recent years attention has been focused on the morphology of the bivalve digestive gland (Sumner, 1966a, b; Owen, 1970; Pal, 1971,1972) but there is little information concerning its role in the storage of energy reserves. Reid (1969) has suggested that in the horse clam, Tresus capax, digestive gland lipid may serve as an energy store which is depleted when food is scarce. Sastry (1966) and Sastry and Blake (1971) have shown that material stored in the digestive tissue of Aequipecten irradians is transferred to the gonad during gametogenesis and Vassallo (1973) has confirmed the transfer of lipid in Chlamys hericia. The digestive gland of My tilus edulis may also have a storage function and may therefore be involved in the utilisation of reserves during starvation. The present paper deals with seasonal changes in the biochemical composition of the digestive gland of M. edulis, and with changes induced by starvation and temperature stress.

The Occurrence of Some Trace Metals in Coastal Organisms With Particular Reference to the Solent Region

Abstract: Measurements have been made, by neutron activation analysis, of arsenic, cadmium, antimony, mercury and zinc in organisms and bottom muds, mainly from Southampton Water and the Solent. The values are on a dry weight basis and refer to whole organism soft tissues unless otherwise stated.Concentrations of mercury in algae ranged from 0·07 to 0·22 ppm and those in animal tissues from 0·06 to 1·9 ppm. The distribution of the element in various tissues of Mercenaria mercenaria was rather uniform, except that the concentration in the gills was about 2·5 times that in the whole organism. Variations amongst organisms from different parts of the Solent area and comparisons with other regions suggested some possible influences of local waste discharge, but there was no evidence of major effects. Anoxic muds contained higher concentrations of mercury than occurred in unreduced surface layers, suggesting mobility in interstitial waters of the uppermost zone and fixation under reducing conditions.

Turbulent Convergent Tidal Fronts

Abstract: A high concentration of certain planktonic animals was found in a frontal region in the English Channel. Temperature, salinity and current measurements and direct visual observations (underwater) describe the nature of the front. It is shown that water depth, season, strong tidal mixing and residence time are important factors leading to the formation and maintenance of a turbulent convergent tidal front.

A Study of the Dissolved and Particulate Trace Elements in the Bristol Channel

Abstract: A study of the dissolved inorganic salts of nitrogen, silicon, phosphorus and carbon and their particulate forms in the Bristol Channel (Abdullah, Dunlop & Gardner, 1973) has shown that the primary sources of these elements are run-off and waste disposal. Furthermore, the slow flushing rate of the Channel plays an important role in the accumulation of these materials in the eastern part. An important constituent of run-off is the heavy metal load especially in industrial waste. Some preliminary investigations (Abdullah, Royle & Morris, 1972; Butterworth, Lester & Nickless, 1972; Nickless, Atenner & Terille, 1972; Preston, 1973) have shown that certain trace metals such as Cu, Pb, Cd, and Zn are added to the Channel in sufficiently large quantities to produce high concentrations not only in the waters of the Severn Estuary and Swansea Bay, but also in the local fauna.

Comparing Species Diversity and Evenness Indices

Abstract: The current interest in diversity as one of the major parameters describing a community has led to an increasing number of published results and theoretical discussions during the last years. Diversity has variously been related to other attributes of the community or properties of the environment, among which time, spatial heterogeneity, stability, primary production, productivity, competition, predation, niche structure and evolution. Although this rather overwhelming amount of possible relations seems somehow too much of a good thing, the importance of diversity remains well established in current ecological theory. One of the most important applications of diversity indices is their usage in the biological assessment of pollution. This immediately raises the problem of comparing diversity indices within habitats in time or between habitats in communi-ties. These comparisons are frequently made, yet the statistical significance of the observed differences or similarities is seldom mentioned. A test for these differences was formulated by Hutcheson (1970) but it apparently failed to attract the attention it deserves. In this study it was our purpose to investigate the distributions of the more important diversity indices and their evenness components in a low-diversity community of meiobenthic copepods of a shallow brackish water pond in northern Belgium. In this habitat the number of species is rather low, which greatly simplifies the analysis, and we hope that the statistical behaviour of the indices we find will hold for other, especially other low diversity communities as in polluted environments, as well. We chose copepods because they are taxonomically well known, the benthos because it is approximately two-dimensional and a shallow environment because of the possibility of accurate sampling.

Infections with Parasitic Copepods in North Sea Marine Fishes

Abstract: A range of 62 species of marine fishes representing 34 families was examined for the presence of parasitic copepods. Forty-one species were found to harbour 39 species of copepod belonging to 9 families. The remaining 21 species of fishes were not infected. The incidence and intensity of infection were recorded and these provided material data on the host-parasite relationships. The site of infection and the developmental stage of the parasite were also recorded. The frequency distributions of number of copepods per host were calculated for Clavella adunca and Bomolochus confusus. The age of the host was shown to influence the frequency distribution of Bomolochus confusus. The host specificity of the copepod species was analysed and 70 % of the species were found to be specific for one host species or for different species of the same genus.

The Food of Deep-Sea Copepods

Abstract: The question of how organisms living below 1000 metres depth in the oceans obtain food in sufficient quantity to survive has lately received a lot of attention (Vinogradov, 1968; Sanders & Hessler, 1969; Fournier, 1972). The oldest and simplest theory, first advocated by Agassiz (1888), is that deep-sea organisms are nourished by a ‘rain’ of organic detritus from overlying surface waters. Detritus is defined to include all organic particles, living and dead, which sink passively. An alternate proposal by Riley (1951), Vinogradov (1962) and Wickstead (1962) is that the main supply of food for deep-sea plankton is conveyed from the euphotic zone by overlapping vertical migratory plankters.

A Revised Check-List of British Marine Diatoms

Abstract: The preliminary check-list of British marine diatoms first appeared in this Journal about 20 years ago (Hendey, 1954), and since that time many advances have been made in the study of these organisms. First, the known flora has been extended very considerably (Hendey, 1964, 1973) and much has been added to our knowledge of the structure of the valve by the use of the scanning electron microscope through the work of Hasle (1964, 1965a, b, 1972) and that of Ross & Sims (1970, 1971). This new information must inevitably lead to a reappraisal of views held on phylogeny within the group and consequently upon its systematic classification. While it would be premature at this stage to over-emphasize the importance of information gained in this way until a wider range of species has been examined, sufficient exists to support some minor changes and prepares the way for more radical changes that the new developments suggest. It should be pointed out, of course, that most of the ‘new information’ should more correctly be interpreted as confirmation of earlier views based solely on structure as seen in the light microscope of classical design and that some of the changes made in the classification as a result of these had been made many years previously, but the scanning electron microscope has enabled us to see more clearly the ultimate structure of the siliceous frustule of the diatom, thus permitting more positive decisions to be made regarding relationships and possible lines of descent.At the First Symposium on Recent and Fossil Marine Diatoms held at Bremerhaven in 1970, Simonsen (1972) put forward some ideas for a more natural system of classification of the centric diatoms.

The Biology of Loligo Forbesi Steenstrup (Mollusca: Cephalopoda) in the Plymouth Area

Abstract: The distinguishing features of the common squid of British waters, Loligo forbesi , are summarized, and contrasted with those of L. vulgaris. The life-cycle and growth of L. forbesi are described, based on samples from trawl catches off Plymouth. This species seems to be an annual - young squid first appear in the trawl in late May, when their length is about 10 or 11 cm. Subsequent growth is rapid, and the males reach 30 cm and the females 25 cm by November. Spawning takes place mainly in December-January, but may continue into the spring. Neither sex survives beyond a single spawning season. Hatching of the spawn probably takes 30–40 days, and if the young squid taken in the trawl in late May hatched in the early part of the same year, a growth rate of about 25 mm/month would be required. Known growth rates for other species of Loligo are about 20 mm/month, so that indicated for L. forbesi does not seem to be impossibly high. The life-cycle is summarized in Fig. 8. There is also a summer spawning population, which grows to a rather smaller size at maturity, and which also seems to be annual. During the summer L. forbesi ranges throughout the English Channel and southern North Sea, particularly in inshore areas. In October the squid migrate farther offshore and tend to occupy the western part of the Channel. Values for total weight of squid/2 h trawl are given, on a monthly basis, for 1966–9. The largest quantities are usually taken in October and November, the highest single figure being 30.54 kg/2 h trawl, in November 1967.

Ultrastructural Observations on Nanoplankton Collected from the Coast of Jugoslavia and the Bay of Algiers

Abstract: A large number of nanoplankton species originally found in the sea around Britain have now been collected from other northern temperate waters (see Leadbeater, 1972 c; Manton & Leadbeater, 1974). It was, therefore, of considerable interest to collect nano-plankton from warmer waters such as those of the Adriatic and Mediterranean. The larger plankton of both the Adriatic and Mediterranean has been the subject of investigation by a succession of scientists from many countries (for references see Tregouboff, 1952). Whilst many workers acknowledged the importance of the smaller plankton from these areas (e.g. Bernard, 1958; Lalami-Taleb, 1971) only a few have attempted to study and identify species belonging to this group. In this respect the meticulous work of Lohmann (1902a, 1911) and Schiller (19136, 19256) requires special mention. Lohmann (1902a), working on the phytoplankton from the coast of Sicily, first used the technique of pumping sea water through filter paper and in this way he was able to collect and identify many minute species for which he later suggested the name ‘ Nannoplankton’ (Lohmann, 1911). On a later excursion to the Atlantic Ocean, Lohmann (1911) found the gentle centrifugation of sea-water samples was a more satisfactory and less destructive way of concentrating small cells. Schiller's most important contribution concerns a phytoplankton study carried out as part of an international hydrobiological survey of the Adriatic Sea during the years 1911–14. Schiller's findings confirmed many of Lohmann's previous observations and added a further range of new species including many green flagellates (Schiller, 1913 6, 1925b).

The Vertical Distribution of the Siphonophores Collected During the SOND Cruise, 1965

Abstract: In many of the more general studies on marine zooplankton the part played by siphonophores is frequently ignored or only given a cursory mention. However, their ecological importance is far from insignificant. In this context we are indebted to the late Mr A. K. Totton whose publications have done much to draw attention to the siphonophores and the part which they play in the zooplankton community. His synopsis of the siphonophores (Totton, 1965) is a masterly work from which any student of this fascinating group can derive much benefit.

Sexual Maturity, Fecundity and Growth of the Turbot Scophthalmus Maximus L.

Abstract: The turbot Scophthalmus maximus L. is a large teleost flatfish of the family Bothidae. Its range extends from the Adriatic (Faber, 1883) and Mediterranean (Morgan, 1956) northwards to the Norwegian coast, and includes the Baltic Sea and waters surrounding the British Isles. It has been recorded as far north as the Lofoten Islands (Fulton, 1905), and is taken occasionally at Faroe, Iceland and Rockall.

The Breeding Cycle and Growth of Hydrobia Ulvae in the Dovey Estuary

Abstract: Hydrobia ulvae has featured in many reports on the ecology of estuaries and mud-flats, yet surprisingly there are few detailed studies on population structure, growth and the breeding cycle. Population densities fluctuate widely from one locality to the next, and the variation in size recorded for the adults suggests significant differences in growth rate and the size at which the snails become sexually mature. The occurrence of Hydrobia in the stomachs offish and birds is well documented (Clay, 1960) and the suggestion that this species may influence the breeding success of some species of bird (Anderson, 1971) illustrates its importance in the ecology of estuaries and salt marshes.

The Growth Kinetics of Isochrysis Galbana in Cultures Containing Sublethal Concentrations Of Mercuric Chloride

Abstract: There is increasing evidence that the specific growth rates of phytoplankton are hyperbolically related to the intracellular concentrations of rate-determining nutrients by expressions of the Michaelis-Menten type used in the study of enzyme reaction kinetics (see, for example, Caperon, 1968; Droop, 1968; Davies, 1970; Paasche, 1973). This has led us to inquire whether there might also be relationships, analogous to those which describe the effect of inhibitors upon the rates of enzyme reactions (Dixon & Webb, 1958) which can be applied to the growth of phytoplankton in the presence of sublethal levels of toxic substances.

Long-term population trends of the benthic macrofauna in the offshore mud of the Northumberland coast

Abstract: The changes in the number of species, the number of individuals and the production of a benthic mud association have been studied for a 4-year period. The numbers of species and the total estimated production appear to have remained substantially stable, but the number of individuals has more than doubled over the period. When considering the high ranking producers, it is clear that not all of these have contributed to the general rise in numbers of individuals. Two species, Ammotrypane aulogaster and Abra nitida have shown an abrupt fall in population numbers and biomass. At the beginning of the investigation in 1971, these species figured importantly in the production estimates with 20 and 6% respectively of the total production. After 1971, both were effectively eliminated from the production of the association.

Cephalopods, blue sharks and migration

Abstract: A small collection of cephalopod remains taken from 26 blue shark stomachs is examined. This includes 92 lower and 97 upper beaks which are identified as far as possible to species. From measurements of the beaks, mean weight and total weight of each cephalopod species is estimated. The presence of oceanic cephalopod remnants in the stomach contents indicates that some sharks caught in the Looe area had recently migrated inshore from deep water.

Lugworm mortalities and a bloom of Gyrodinium aureolum Hulburt in the eastern Irish Sea, Autumn 1971

Abstract: A bloom of the dinoflagellate Gyrodinium aureolum Hulburt in the eastern Irish Sea during September and October 1971 was accompanied by unusual mortalities of Arenicola marina L. and Echinocardium cordatunt Pennant. Observations in the field and laboratory suggest that the mortalities may not have been directly related to the occurrence of Gyrodinium but could have been a consequence of unusual climatic conditions which resulted in oxygen depletion in benthic substrates. The decomposition of the bloom possibly aggravated the situation.

A Preliminary Consideration of the Taxonomic Position of Palmaria Palmata (Linnaeus) Stackhouse = Rhodymenia Palmata (Linnaeus) Greville

Abstract: The life history and taxonomic position of Rhodymenia palmata (Linnaeus) Greville, one of the commonest red algae in the northern hemisphere, have been a source of considerable speculation. Carpogonial plants and carposporangial plants are unknown although tetrasporangial plants are common and spermatangial plants have been reported on numerous occasions. A parallel situation occurs in the genus Halosaccion Kutzing for which carpogonial and carposporangial plants have never been recorded and spermatangial plants are well known only in the species Halosaccion ramentaceum (Linnaeus) J. G. Agardh. It is proposed in this paper to consider the relationship of Rhodymenia palmata to the other genera of the Rhodymeniaceae (Rhodymeniales) particularly Halosaccion and Leptosarca Gepp & Gepp.

Biochemical changes during growth of the spat of the oyster, Ostrea edulis L.

Abstract: The biochemical composition of three batches of Ostrea edulis L. spat was determined during post-settlement growth. The spat were from spatfalls in January, March and June. For the first few months after settlement the neutral lipid (triglyceride) content was greater than the glycogen content. However, in three- to five-month-old spat the glycogen content became greater than that of neutral lipid.

The Occurrence and Significance of Tooth Cuts on the Blue Shark (Prionace Glauca L.) From British Waters

Abstract: In this investigation of the wounds occurring on blue sharks, tooth cuts were found only on females over 180 cm long, supporting the view that they are courtship scars incurred during breeding. However, it seems unlikely that these sharks normally mate in British waters. It is suggested that tooth cuts can provide information on the size at sexual maturity of the blue shark in European seas.