bluuebunny/crossref_metadata_2025 huggingface dataset:
Feeding, Growth, Reproduction and Nitrogen Utilization by the Harpacticoid Copepod,Tigriopus Brevicornis
Authors: Harris R. P.
Published: May 2009

Growth of the littoral harpacticoid copepodTigriopus brevicornisO. F. Müller was measured in an intertidal rock pool. The generation time at the field temperature of 15°C was 31 days, and growth during this period resulted in an increase of 1.1829 μg body nitrogen.

Measurements of nitrogen excreted by developmental stages were made on animals removed from the natural population. Ammonia comprised on average 89.7% of the total nitrogen excreted by adults. Some measurements of phosphorus excretion indicated a nitrogen: phosphorus ratio in excretory products of 4.86. Adult females excreted 27.2 μg N/mg dry wt/day, representing a release of about 30% of body nitrogen daily. Excretory rates of earlier copepodite and naupliar stages were higher.

The efficiency with which ingested food was assimilated was measured for animals feeding on natural suspended matter obtained from the pool. Assimilation efficiencies averaged 75.4%.

Egg production was measured at a range of temperatures in the laboratory, enabling an estimate to be made of total production by an individual female. At 15°C females produced an average of ten egg sacs in 30 days.

Measurement of nitrogen lost during moulting suggested a value of 6% of total body nitrogen.

The data obtained have been used to estimate growth efficiency in terms of nitrogen during the entire life-history of a female in the pool. Gross growth efficiency calculated for the period of growth from egg to adult is 13.0% and the net efficiency 17.2%. Efficiencies of egg production by the adult female are higher, the gross efficiency being 22.1% and the net 29.3%. During the entire life-span 72.9% of assimilated nitrogen is expended in metabolism, 3.9% in growth, 0.4% as moults, and 26.6% in egg production.
Addendum to A Micro-Analytical Scheme for the Biochemical Analysis of Marine Invertebrate Larvae
Authors: Holland D. L. , Hannant P. J.
Published: May 2009

A micro-analytical scheme for the determination of protein, carbohydrate, lipid and RNA levels in marine invertebrate larvae has been described in a previous paper (Holland & Gabbott, 1971). This addendum describes minor modifications to the scheme so that the level of DNA may be determined and includes a different procedure for the determination of RNA by u.v. absorption. DNA and RNA levels were determined in a number of nauplii and veliger larvae.
Adaptation of the PolychaeteNereis Diversicolorto Estuarine Sediments Containing High Concentrations of Zinc and Cadmium
Authors: Bryan G. W. , Hummerstone L. G.
Published: May 2009

In the first paper of this series (Bryan & Hummerstone, 1971) it was shown that in the estuarine polychaeteNereis diversicolorO. F. Müller the concentration of copper is roughly proportional to that of the surrounding sediment. On the other hand, concentrations of zinc appeared to be relatively independent of those in the sediment and it was suggested that the level of zinc in the worm is regulated.
An Experimental Assessment of the Status of the Species Enteromorpha Intestinalis (L.) Link and Enteromorpha Compressa (L.) Grev.
Authors: De Silva M. W. R. N. , Burrows Elsie M.
Published: May 2009

Many workers have experienced difficulties in trying to identify species within the genus Enteromorpha. The difficulties arise from our lack of knowledge of the range of variation for the characters used to delimit the taxa and of the sources of the variation shown.

Enteromorpha intestinalis (L.) Link was originally described by Linnaeus (1753) under the name Ulva intestinalis as ‘Ulva tubulosa simplex’ and Enteromorpha compressa (L.) Grev., also by Linnaeus (1753) under the name Ulva compressa as ‘Ulva tubulosa ramosa compressa’. In their interpretations by later authors, the two species differ only in that the former is unbranched and the latter branched. In their cell size, in the unordered arrangement of the cells and in the single pyrenoid in the chloroplast, they seem to belong together. Whether or not a plant is branched would seem to be a straightforward character to use in practice, but for an alga of this kind this is not necessarily so. In its development the unbranched tube of the thallus begins life as a zoospore or zygote which at first divides transversely to form a short uniseriate filament and later by radial longitudinal divisions, the subsequent expansion of which leads to the formation of the hollow tube. In the formation of branches, individual cells, usually towards the base of the frond, divide by a single periclinal division. The outer cell of the pair thus formed then divides transversely forming a single-celled filament, later dividing by radial longitudinal divisions and repeating the structure of the main axis.
The Size of Diatoms V. The Effect of Animal Grazing
Authors: Wimpenny R. S.
Published: May 2009

It has been suggested in Part IV of these contributions that the larger diameter of centric diatom cells met with in collections made in the oceans in the lower latitudes might be caused in part by the relatively greater grazing known to take place in these areas (Steemann-Nielsen, 1962; Lohmann, 1912). Eight series of experiments were therefore carried out to determine any effect that might be attributed to animals grazing on populations of centric marine diatoms.
A New Index Measuring Evenness
Authors: Heip C.
Published: May 2009

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 Rényi'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.
Comparing Species Diversity and Evenness Indices
Authors: Heip C. , Engels P.
Published: May 2009

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.
The Hydrolysis of Ammonium Ions in Sea Water-a Theoretical Study
Authors: Whitfield M.
Published: May 2009

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 equationThe 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).
Impaired Osmoregulation in Infected Salmon, Salmo Salar L.
Authors: Gardner M. L. G.
Published: May 2009

Euryhaline fishes, such as the salmon and the eel, adapt the osmoregulatory mechanisms of their gills, kidney and intestine so that they retain water while they are in the sea but retain salt while in fresh water (e.g. Krogh, 1939). Thus on entering fresh water the osmotic pressure of plasma in the Atlantic salmon, Salmo salar L., only falls from some 410 m-osmole/1 to about 340 m-osmole/1 (calculated from the freezing point data of Benditt, Morrison & Irving, 1941), although the osmotic pressure of the environment falls from around 1000 m-osmole/1 to almost zero.
Long Term Changes in Abundance of Eggs of the Cornish Pilchard (Sardina Pilchardus Walbaum) Off Plymouth
Authors: Southward A. J.
Published: May 2009

The inshore fishery for the pilchard in Cornish waters has existed for several hundred years, and such records as are available concerning fluctuation in catches and market conditions have been reviewed by Couch (1865), Cushing (1957) and Culley (1971). Although pilchard have been landed from Lyme Bay, from the eastern half of the Channel, and from the southern North Sea (Couch, 1865; Furnestin, 1945; Cushing, 1957; personal communications G. T. Boalch) the catches have usually been incidental to other fisheries and more sporadic than in Cornish waters. Traditionally there are three areas fished for the Cornish pilchard: on the north-west coast around St Ives; in Mounts Bay and towards the Scillies; and between the Lizard Pt and Bolt Tail in Devon (Couch, 1865; Culley, 1971). The latter region, constituting the inshore waters of south-east Cornwall and south Devon, effectively forms the eastern limits of the regular occurrence of commercial shoals. Knowledge of the breeding and life-history of the fish in this region has always been scarce and subject to much hearsay evidence (reviewed in Southward, 1963). Up to quite recently it was thought that the main spawning area lay well to the west of the entrance to the Channel, and it was not until the investigations reported by Corbin (1947,195°) a nd Cushing (1957)tnat it was conclusively shown that extensive spawning can occur within the English Channel from May to October. The relationship of the spawning in the western Channel to the other areas of spawning off the entrance to the Channel and in the northern Bay of Biscay is illustrated in a recent series of reports (Arbault & Boutin, 1968; Arbault & Lacroix-Boutin, 1969; Arbault & Lacroix, 1971; Wallace, P. D. & Pleasants, C. A., duplicated ICES meeting paper CM 1972/J: 8), and is further demonstrated by Demir & Southward (1974) in discussing the results of a study of small scale seasonal changes in spawning intensity in inshore waters.
The Breeding Cycle and Growth ofHydrobia Ulvaein the Dovey Estuary
Authors: Fish J. D. , Fish Susan
Published: May 2009

Hydrobia ulvaehas 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 ofHydrobiain 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.
Effects of Starvation on Structure and Function in the Digestive Gland of the Mussel (Mytilus EdulisL.)
Authors: Thompson R. J. , Ratcliffe N. A. , Bayne B. L.
Published: May 2009

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 ofAequipecten irradiansis transferred to the gonad during gametogenesis and Vassallo (1973) has confirmed the transfer of lipid inChlamys hericia. The digestive gland ofMy tilus edulismay 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 ofM. edulis, and with changes induced by starvation and temperature stress.
Biochemical Studies on Marine Zooplankton XII. Further Investigations on Euphausia Superba Dana
Authors: Ferguson C. F. , Raymont J. K. B.
Published: May 2009

Interest has developed recently in the biochemical composition of zooplankton, particularly in relation to seasonal changes. An earlier study (Raymont, Srinivasagam & Raymont, 1971b) on deep frozen Antarctic krill, Euphausia superba, collected over approximately 5 weeks in December/January 1968/69 suggested that protein was the main constituent and lipid much more variable. Despite the variability the mean lipid content during January was distinctly higher than in the previous month, thus supporting the findings of Kryuchkova & Makarov (1969) that lipid content of krill tends to increase as the summer advances. However, collections of material from the Antarctic have tended to be limited both in location and season while methods of preservation have varied. It seemed desirable to follow changes in the biochemical composition of krill collected from a somewhat wider area and over a longer period. Moreover, the more extensive material gave opportunity for a more detailed examination of specific fractions, such as the amino acids of Euphausia superba. Preliminary investigations (Srinivasagam, Raymont, Moodie & Raymont, 1971) on the amino acid composition of protein hydrolysates showed good agreement with the results of some other authors. However, the findings of Burkholder, Mandelli & Centeno (1967) and especially of Moiseev (1970) showed certain differences.
Incubation in British Decapod Crustacea, and the Effects of Temperature on the Rate and Success of Embryonic Development
Authors: Wear Robert G.
Published: May 2009

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 incubating 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.
Startle Response in Herring: The Effect of Sound Stimulus Frequency, Size of Fish and Selective Interference With The Acoustico-Lateralis System
Authors: Blaxter J. H. S. , Hoss D. E.
Published: May 2009

Herring (Clupea harengus L.) show a marked ‘startle’ response when subjected to sound stimuli from a vibrating source (Blaxter, Gray & Denton, 1981c). The response, which occurs at a consistent threshold, is elicited by the first cycle of a tone burst or noise, the threshold to one cycle being the same as for a burst of many cycles. Furthermore, if the onset of the tone burst is ‘ramped’ so that it takes several cycles for the full amplitude to be reached, the threshold is markedly raised. Under some conditions the fish move away from the source, showing that they can determine its direction even though the stimulus is confined to a single cycle. The relative roles of sound pressure and particle velocity in providing information about the amplitude and direction of the noise have not been firmly established. Present evidence suggests that pressure is important in triggering the response and probably in measuring the strength of the stimulus. A vector such as particle velocity provides the directional information used in the response. The response can be very fast with a latency of about 25 msec and a contraction time of about 20 msec (Blaxter, Denton & Gray, 1981 b). In these very fast reactions the Mauthner cells probably constitute the motor pathway (Diamond, 1971).
The Age And Growth of Callista Chione
Authors: Forster G. R.
Published: May 2009

Callista chione (L.). is a fairly large, handsome bivalve of the family Veneridae. It is found around the coasts of Devon, Cornwall and Wales, though its distribution extends southwards to the Mediterranean. It is usually uncommon but has been found to occur at the eastern end of Whitsand Bay, near Plymouth at a density of about 1 per m2. Several specimens were taken in 1975 while testing a water lift system for the use of aqualung divers. Most of the shells were observed to bear a noticeable growth check in the form of a ridge several millimetres from the shell margin (Fig. 1). This ridge was not found in the older specimens in the laboratory's museum collection. To try to find out the cause of this growth check a tagging experiment was undertaken in 1976, although it was not possible to measure and mark out large numbers; recaptures in the following two years have been sufficient to provide some evidence for the average growth increment of different sizes of shell.
Control of the Reproductive Cycle in Female Eulalia Viridis (Polychaeta: Phyllodocidae)
Authors: Olive P. J. W.
Published: May 2009

Eulalia viridis (L.) is one of a group of polychaete species which are being used in an experimental analysis of the regulation of gametogenesis and reproduction. The back-ground to these studies and some of the preliminary results have been discussed recently by Olive (1980). Despite the abundant data demonstrating the frequent occurrence of well-defined reproductive cycles in marine invertebrates and observations on the correlations between reproductive events and environmental conditions, the mechanisms by which the reproductive cycles of individual species are controlled are very poorly understood. It has generally been accepted since the publication of the important paper of Orton (1920) that the temperature cycle in temperate and boreal regions plays an important role in determining the reproductive cycle, but the nature of the control mechanism is not, in general, understood and is likely to vary markedly between species. Environ-mental conditions such as relative daylength or biological factors such as the quantity and identity of the phytoplankton organisms (Himmelman, 1978, 1979) could also play important roles in regulating the sequence of cellular events which culminates in successful reproduction. These general problems have been discussed by Giese (1959) and more recently by Barnes (1975), Giese & Pearse (1975) and specifically in relation to Polychaeta by Clark (1979) and Olive (1980).
The Vitamin B12Requirement Of The Marine RotiferBrachionus Plicatilis
Authors: Scott J. M.
Published: May 2009

The nutrient requirements of many algae are well documented, with most algae being found to need only one or two vitamins. In the case of their predators, only a handful of microinvertebrates have had their diets and even fewer their vitamin requirements denned. Thus, any progress in this field together with the mode of nutrient uptake, must lead to a better understanding of the component-transfer in the food chain.

Brachionus plicatilisMüller has been reported to require vitamin B12(Droop & Scott, 1978). The work described in this paper sought first, to confirm this and then to establish the mode of uptake. The algaBrachiomonas submarinavar.pulsiferaDroop was used to investigate the first of these questions as the writer had previous experience with it in steady-state energetics work. The algaDunaliellaSMBA Strain 246 was used to examine the mode of uptake by the rotifer since this had also been found to be a good food organism. The possibilities considered were uptake: (a) via the algal cell; (b) directly from solution; (c) a combination of both. Mode of vitamin B12uptake is of particular interest as it may be representative of the pathway of many of the rotifer's water soluble micronutrients.

Before considering the influence of the vitamin onBrachionusinvestigations were made into the relationship between the vitamin and the two food-algae. It has already been established thatBrachiomonashas a definite requirement (Droop, 1961) andDunaliellano requirement for vitamin B12(Turner, 1979). It was of interest to see if they took-up the vitamin in the manner shown byMonochrysts, a B12requirer, andPhaeodactyluma non-requirer (Droop, 1968).
The Occurrence of Thalassomyces Fagei (Ellobiopsidae) in Euphausiids (Crustacea: Malacostraca) in the North–East Atlantic and Northern North Sea
Authors: Smith John W.
Published: May 2009

The ellobiopsid genus Thalassomyces is of uncertain systematic position, having been allied at various times with the fungi, algae and protozoa, and little is known of its biology. Discovery of a flagellate stage suggested to Gait & Whisler (1970) that the genus is a member of the achlorophyllous Dinophyceae (Dinoflagellata). T. fagei (Boschma, 1949) appears to be restricted to euphausiids (of which there are 85 valid species in 11 genera-see Mauchline & Fisher, 1969). According to Vader (1973), T. fagei has been recorded in different areas from various euphausiid species, i.e. in 11 (perhaps 12) species of Euphausia, two of Nycliphanes, three of Thysanoessa, and in Nematoscelis difficilis and M. novegica. Other Thalassomyces species are found in mysid, decapod and amphidpod crustaceans (Vader, 1973).
Distephanus Speculum: Double Skeletons with One Aberrant Partner
Authors: Boney A. D.
Published: May 2009

Skeletal form is the key to silicoflagellate taxonomy. Variations in skeleton morphology have been frequently described for the generaDictyochaandDistephanus(Lemmerman, 1908; Deflandre, 1932; Hovasse, 1932; Frenguelli, 1935; Boney, 1973, 1976), and the wide ranging skeletal variations observed with clonal cultures ofDictyocha fibulaEhrenb. underline the potential plasticity of skeleton formation in this species, (Van Valkenberg & Norris, 1970). Sufficient information now appears available to indicate where taxonomic confusions may arise, particularly when single skeletons are observed either in phytoplankton samples or in fossil deposits. Paired skeletons are predivision stages (Gemeinhardt, 1930; Hovasse, 1932; Marshall, 1934; Boney, 1976). The juxtaposition of the two skeletons in this predivision stage allows a more critical assessment of the taxonomic significance of an aberrant form.
The Rate of Feeding by Mytilus in Different Kinds of Suspension
Authors: Jørgensen C. Barker
Published: May 2009

The feeding rate of small specimens of Mytilus edulis (L.) has been determined in suspensions of colloidal graphite (‘Prodag’, grade ‘C’, and ‘Aquadag’, grade ‘S’), of flagellates, and of Nitzschia dosterium. The feeding rate was measured as the volume of water cleared from particles per unit time. In graphite suspensions, with particle size of about 4–5μ, as a rule only a small percentage of the particles was retained by the gills, whereas flagellates of about the same size were normally nearly all retained.
Certain Effects of Agitation Upon the Release of Phosphate from Mud
Authors: Stephenson William
Published: May 2009

When sea water is stirred with mud and then filtered, its phosphate concentration may either increase or decrease. When the filtrate is ultrafiltered, the concentration increases.

Similar increases occur when the filtrate is stored in glassware, and these obscure any effects of the presence of colloidal material. On storage concentrations rise for about 2 hr., and then fall to as low as 2 mg./m.3 P2O5 in 18 hr.

Rise and fall are both prevented by the addition of formalin, chloroform or toluene, and are more noticeable in small containing vessels. Both occur during either day or night, and when temperatures are either rising or falling.
British Folliculinidae (Ciliata, Heterotricha)
Authors: Das S. M.
Published: May 2009

A brief résumé is given of the work done on British Folliculinidae up to the present time.

Descriptions follow of eight British species, many of which are revised accounts based on personal observations.

A new species, Folliculinopsis elongata, is described.

A revised key for the identification of British Folliculinidae is given.
A Statistical Study of the Variation in Vertical Plankton Hauls, with Special Reference to the Loss of the Catch with Divided Hauls
Authors: Barnes H.
Published: May 2009

The analysis of data on replicate vertical plankton hauls gives a value of the order of 35 % for the coefficient of variation of a single observation for a haul of moderate length. The results are similar to those presented by Winsor & Walford (1936), and Winsor & Clarke (1940); and are not at variance with the suggestion that the animals are randomly distributed, and that the variations obtained are largely dependent upon variation in the volume of water filtered by the net.
Respiratory Movements ofArenicola MarinaL.: Intermittent Irrigation of the Tube, and Intermittent Aerial Respiration
Authors: Wells G. P.
Published: May 2009

The worms were housed in glass U-tubes, and were able to get a supply of aerated water from above by making pumping movements. The water movements were recorded kymographically. The experiments generally lasted for 24 hr. or longer.
On the Hydroid of Eutima Gracilis (Forbes and Goodsir)
Authors: Russell F. S.
Published: May 2009

In July 1938 I succeeded in rearing the hydroid of Eutima gracilis (Forbes and Goodsir) (also known as Saphenia gracilis) from adult medusae which liberated their eggs and sperm in finger-bowls of sea water. These hydroids were only in the primary polyp stage, and I withheld publication hoping to repeat the work later and perhaps rear the hydroid to a more advanced stage. As it is unlikely that I may now have the opportunity of doing this it seems worth while to publish a short account with figures of the polyp.
The Structure and Mode of Life of the Pyramidellidae, Parasitic Opisthobranchs
Authors: Fretter V. , Graham A.
Published: May 2009

The family Pyramidellidae contains a number of species of gastropod molluscs of similar structure and mode of life.

The shell is calcareous and spirally wound and may be closed by an operculum. The foot bears a transverse fold anteriorly, the mentum (Fig. 1, MT), separating the opening of the penial sheath (PO) below from the mouth (M) above. It has a lateral glandular streak on each side (Fig. 2), presumably sensory.

The head has ear-shaped tentacles (Fig. 1, T), richly innervated and with cilia setting up a strong water current, so that they constitute a powerful sensory mechanism. The eyes (E) lie between the tentacles.
Observations on the Absorption of Radioactive Strontium and Yttrium by Marine Algae
Authors: Spooner G. M.
Published: May 2009

Certain marine algae were treated with sea water containing carrier-free radioactive strontium (mixture of Sr89 and Sr90), to test whether these ions were taken up by the weeds.

At the same time the behaviour of radioactive yttrium (Y90), which occurred as a short-lived daughter-product of Sr90, was investigated by the expedient of studying the ‘decay’ characteristics of specimens of water and weed.

Promising possibilities of this technique, by which an isotope is made available for study by applying its parent substance, are pointed out.

Radioactive strontium is extracted from sea water by the brown sea-weeds, in particular by Fucus serratus.

It is held that this effect is simply a result of ionic exchange, and that the algae regularly contain many times as much strontium in their cell fluids as exists in sea water.
On the Volume Measurement of Water Filtered by a Plankton Pump, with Some Observations on the Distribution of Planktonic Animals
Authors: Barnes H.
Published: May 2009

The accuracy of volume estimation in filling a marked tank by means of a plankton pump has been determined. The method even in its simplest form is satisfactory under good conditions. Further refinements, in which the plankton was filtered off, after filling a modified tank (for example with an overflow device) would no doubt increase the accuracy.

A device is described by which, using an ex-N.F.S. pump, a constant (but variable by selection) volume of water can be taken without the use of large tanks.

A small number of sets of samples taken with adequate volume control indicate the same order of variability as net hauls. Comparison of the distribution of x2 for paired samples with nets and pumps also indicates variation of a similar type.

These results suggest that the variability of net hauls is not entirely due to the variations in the volume of water filtered. Further work is in hand to elucidate this question.
An Apparatus for Producing Artificial Tides
Authors: Aleem Anwar Abdel
Published: May 2009

It is often desired to grow animals and plants of the intertidal zone in the laboratory, under conditions as far as possible simulating those in nature and with the least trouble and expense. This need was felt by the writer during an ecological study of the diatoms inhabiting the mud-flats at Whitstable, Kent. It was found necessary to maintain such diatoms in the laboratory in London in a healthy condition for several days so as to study the effect of light and tides on their movements. The apparatus described in this paper was therefore devised. It has an advantage over other tidal systems (Bracher, 1919; Martin & Reid, 1935) in that the substratum could be automatically alternately flooded and drained at regular intervals by a much simpler mechanism. Besides, it is more handy and can be operated with only a small supply of sea water, a matter of some importance in localities remote from the sea.

It consists of a tidal chamber, T, and a reservoir, R (Fig. I). The former is an inverted bell-jar fitted with a rubber bung through which passes a long glass tube, g, which extends to the base of the reservoir. At the upper end of the tube is a small funnel by which sea water enters the apparatus. A ⋯tube, t, serves to connect the tidal chamber and reservoir, its horizontal arm being connected to the siphon S.

The wide-mouthed bottle constituting the reservoir is fitted with a stopcock, v, which is useful for expelling air when setting up the apparatus.
The Last Larva and Post-Larva of Typton Spongicola from Plymouth (Crustacea Decapoda)
Authors: Lebour Marie V.
Published: May 2009

The first larva of Typton spongicola was described in 1925 from the eggs carried by the parent (Lebour, 1925). No later stages are known; therefore it was interesting to find a last larva in the plankton from 2 miles north-east of the Eddystone (21 August 1946), which changed to the post-larva in the laboratory. There seems to be no doubt that the identification is correct although, surprisingly, the antennal scale, rudimentary in the adult, is still large. The agreement in colour of the last larva and post-larva with the newly hatched first larva, and the great similarity in the structure, in most ways, of post-larva and adult, makes it practically certain that we are dealing with T. spongicola.
The Seasonal Abundance of Young Fish X. the Year 1948
Authors: Corbin P. G.
Published: May 2009

Records of the young fish and plankton of Plymouth off-shore waters taken in ½ hr. oblique hauls of the 2 m. stramin ring-trawl were continued in 1948. They show an even lower production of young fish than in 1947 and a continued poverty of plankton organisms other than young fish. The dates on which collections were made are given in Table I.
Cascading Over the Continental Slope of Water from the Celtic Sea
Authors: Cooper L. H. N. , Vaux David
Published: May 2009

In the Celtic Sea, to the south of Ireland, water in some winters becomes sufficiently cooled and heavy to flow to the edge of the continental shelf and to run down the continental slope to a depth of several hundred metres. A theory of the phenomenon, termed ‘cascading’, has been developed. Three winters have been examined in detail.

In February 1927 much water, heavy enough to cascade, was present in the Celtic Sea and also in the English Channel. A probable course and speed of the cascading water over the shelf has been established. Since there were few observations of salinity and temperature over or beyond the slope, and none of oxygen anywhere, the theory cannot be completely established on the basis of the 1927 observations, full though they were.
Halacaridae (Arachnida:Acarina)
Authors: Fountain H. C.
Published: May 2009

The nomenclature follows André (1946). No Acarina were listed in the Plymouth Marine Fauna (Mar. Biol. Assoc., 1931), but Hydrogamasus littoralis, Rhombbgnathus pascens, R. seahami, and Halacarus basteri have since been recorded from Wembury (Colman, 1940).
Observations on the Gymnosomatous Pteropod Clione Limacina (Phipps)
Authors: Morton J. E.
Published: May 2009

Some features of the digestive and reproductive systems, as well as the habits and swimming of the pteropod Clione limacina have been studied from specimens of the dwarf ‘southern’ race, which occurs at Plymouth. The animal swims rapidly by the sculling action of its two short rounded ‘wings’ or parapodia. Its buccal mass is characterized by specialized prehensile organs, consisting—as well as the radula—of adhesive tentacles (cephaloconi) and a pair of hook sacs. The rest of the gut is simple, consisting chiefly of a ‘stomach’ formed by two spacious digestive diverticula, that have replaced the true stomach. The lining includes absorbing-digestive cells and excretory cells. C. limacina is a protandrous hermaphrodite. The size distribution of a sample of 338 is shown. The youngest specimens are all males; in older groups developing oocytes are found, and in the largest are eggs not yet ready for shedding (September), as well as sperms. The genital tract is of the primitive opisthobranch form, with a sperm-storing hermaphrodite duct, albumen gland and mucus gland. An external seminal groove leads forward to the penial sheath in the head. The structure of the penis and prostate is described, and some previous views on the nature and functioning of these parts are criticized. Finally, the relationships of the gymnosomatous and thecosomatous pteropods are briefly reviewed, and the use of separate orders is recommended in place of the recently revived single group Pteropoda.
Notes From the Plymouth Aquarium. III.
Authors: Wilson Douglas P.
Published: May 2009

The present notes (see also Wilson, 1949, 1953) are mainly concerned with the breeding habits of two fishes commonly kept in marine aquaria. These habits may be familiar to keepers of other large marine aquaria, but I have failed to find any account of them in scientific literature other than a very brief and inadequate description by Raffaele (1898, p. 328) of the nesting of Cantharus vulgaris (= Spondyliosoma cantharus) in the aquarium at Naples. The scientific names of species mentioned follow the Plymouth Marine Fauna third edition (Marine Biological Association, 1957)
Biological Differences Between Sea Waters: Experiments in 1954 and 1955
Authors: Wilson Douglas P. , Armstrong F. A. J.
Published: May 2009

In 1954 and 1955 various natural, artificial and treated sea waters were tested with developing eggs of Echinus esculentus. The following are the main observations:

1. Sea waters filtered through Doulton candles at the time of collection and proved bacteriologically sterile until use were very little different from sea waters collected at the same time in the ordinary way and not sterile. (Expts. 1, 3, 8 and, with qualifications, 6.)

2. Undiluted Celtic sea bottom water and undiluted Celtic mud ‘extract’ were harmful to the eggs, but small volumes of both added to natural sea waters and to artificial sea water had a stimulating effect. (Expt. 1.)

3. In water from near the bottom at E1 eggs did worse, in 1954, than in surface water from the same locality. In 1955 they did slightly better in the deeper water. (Expts. 3, 4 and 7.)

4. Eggs placed immediately after fertilization in water from near the bottom at E1 (and from near the bottom at the Echinus ground) and transferred at first cleavage to surface waters were affected unfavourably. (Expts. 3, 4 and 7.) Artificial sea water had no such effect. (Expt. 5.)

5. The addition to natural and to artificial sea waters of filtrates from culture medium (‘erdschreiber’) and from thick cultures of diatoms and flagellates had no significant effects on the eggs developing in those waters. (Expt. 6.)

6. In 1955 surface water from the Clyde was a better medium for development than surface water from E1. The difference was similar to that frequently observed several years previously. (Expt. 7.)

7. Extracts of natural sea waters made by a new process were non-poisonous, but the experiment in which they were added to artificial sea water was inconclusive owing to the eggs proving to be of poor quality. (Expt. 8.)
Some Observations onEvadne NordmanniLovén
Authors: Bainbridge V.
Published: May 2009

During 1951Evadne nordmanniwas present in the Clyde plankton from late February to the end of October and was most abundant during May and early June. The bulk of the population was always found in the top 30 m. Reproduction is mainly parthenogenetic; sexual individuals first appeared in May and sexual reproduction was most intense during October.

The relation between maternal size and stage of embryonic development is described. Sexual females showing the formation of a resting egg are large and have previously produced at least one brood by parthenogenesis.

Of the females with embryos at an early stage of development the primiparae have smaller broods than larger and older individuals. During the development of embryos some may be resorbed and in the primiparae this results in a decrease of embryo number with increase of size. Larger individuals tend to produce larger broods of young.

There was a considerable decrease of size from June to July and a partial recovery in August. These fluctuations follow similar fluctuations in embryo production.

The reproductive capacity of the parthenogenetic females and the intensity of sexual reproduction did not show any clear relationship, though there are indications that the latter is favoured by moderate rather than severe depression.

Food organisms are captured only during the hours of daylight.Evadneappears to be a selective feeder the diet of which consists mainly of tintinnids and peridinians.

Several aspects of the biology of the species are discussed with reference to the findings on the food and feeding habits.
Phosphorus and Silicon in Sea Water off Plymouth During 1956
Authors: Armstrong F. A. J.
Published: May 2009

The results of analysis of sea water from the International Hydrographic Station E1 during 1956 are presented in graphical form and as integral mean values for the water column of 70 m. The seasonal variation is shown; it appears that consumption of phosphate in the spring outburst of plants was 0·34 μg atom P/l., and that of silicate 2·78 μg atom Si/1. The spring outburst was followed more closely than usual in the period 26 March to 24 April during 4 weeks of rather bright weather. Nearly all the silicate in the water was taken up, and some phosphate left, and it seems that the rapidly growing diatoms, which predominated at the time, were deficient in silicon. It is suggested that in the deep water they continued to absorb silicate, although not receiving enough light for growth and division.
Further Observations on Proprioceptors in Crustacea and a Hypothesis About Their Function
Authors: Alexandrowicz J. S.
Published: May 2009

In the coxal region ofEupagurus bernardusthe following receptor organs have been found: (1) a muscular receptor spanning the thoracico-coxal articulation, its innervation, in which several neurons take part, being arranged on a similar pattern as inCarcinus; (2) two innervated elastic strands running along the bundles of mm. levator and depressor basipoditis respectively and inserting into the tendons of these muscles; (3) a coxo-basipodite receptor consisting of connective tissue strand with numerous bipolar nerve cells ending on it. With the exception of the coxo-basipodite receptor, all sensory neurons of these organs have their cell bodies located in the central nervous system.

It is suggested that these receptors convey impulses elicited by the movements of the legs and some hypotheses concerning the role of each of them are put forward.
An Adult Digenetic Trematode From an Invertebrate Host:Proctoeces Subtenuis (Linton) From the Lamellibranch Scrobicularia Plana(Da Costa)
Authors: Freeman R. F. H. , Llewellyn J.
Published: May 2009

The digenetic trematodeProctoeces subtenuis(Linton, 1907) is recorded from the kidney of the lamellibranchScrobicularia plana(da Costa). At Chalkwell in Essex all of nearly a thousandS. planaexamined were found to be infected, as were three of approximately 150S. planaat Whitstable in Kent. The average number of parasites per host was between four and five. NoProctoeces subtenuiswere found inScrobicularia planaexamined from other localities in Essex, Devon, Wales and Suffolk. The environmental conditions of a parasite in the lamellibranch kidney are discussed. It was found that the kidney fluid surrounding the parasites varies in osmotic pressure.

The anatomy of the parasite is described. The excretory bladder has a cellular wall, thus disagreeing with the inclusion ofProctoeces subtenuisin La Rue's superorder Anepitheliocystidia. The red colour of the parasite is due to a native haem pigment. The egg capsules are hardened by a quinone-tanning mechanism, but incubation with catechol, protocatechuic acid, and dopa failed to reveal the presence of a phenol-oxidase.

The species ofProctoecesare reviewed, and some revisions suggested.P. magnorusManter, 1940 is considered a synonym ofP. subtenuis, and the synonymy ofP. erythraeusOdhner, 1911 withP. subtenuisis confirmed. The differences betweenP. insolitus(Nicoll, 1915) andP. subtenuis, and betweenP. maculatus(Looss, 1901) andP. subtenuis, require re-examination. It is considered thatP. macrovitellusWinter, 1954 should be excluded from the genusProctoeces. A definitive host list ofProctoecesspp. is given.

The adult nature ofP. subtenuisfromScrobicularia planais discussed, and it is suggested thatProctoeces subtenuisin the Thames estuary shows an abbreviated life cycle restricted to invertebrate hosts.
Underwater Observations on the Fauna of Shallow Rocky Areas in the Neighbourhood of Plymouth
Authors: Forster G.R.
Published: May 2009

A brief description is given of the commonest sessile animals observed by diving from twelve positions near Plymouth, including three offshore reefs. The coelenterate Corynactis viridis is generally abundant on shaded rock surfaces. Many sessile species, even where common, tend to be dispersed in scattered patches or colonies; from this it is suggested that their distribution is affected by predation from browsing animals, particularly Echinus esculentus.
The Tapetum inScyliorhinus Canicula
Authors: Nicol J. A. C.
Published: May 2009

Tapeta were examined of light- and dark-adapted dogfish.Scyliorhinus canicula. The tapetum in the eye of this fish is fixed; pigment processes in the tapetum do not move when a fish is changed from dark to light and vice versa. A black ventral field and a bright dorsal fundus are always present.
Studies onEctocarpusin Culture. I. Introduction and Methods of Obtaining Uni-Algal and Bacteria-Free Cultures
Authors: Boalch G. T.
Published: May 2009

Details are given of the culture apparatus and methods found successful for the laboratory culture of species ofEctocarpus. In attempts to obtain uni-algal cultures of this genus several common methods were tried but only one of them, a modification of the plating technique, proved successful. Methods of washing and dilution were unsuccessful in giving bacteria-free cultures, presumably due to bacteria closely adhering to the cell walls. Ultraviolet irradiation was also unsuccessful but treatment with penicillin gave bacteria-free cultures ofE. confervoidesandE. secundus (Giffordia secunda).
The Osmotic Mechanism of the Cuttlebone
Authors: Denton E. J. , Gilpin-Brown J. B. , Howarth J. V.
Published: May 2009

Experiments are described which test the hypothesis that the cuttlefish controls the relative volumes of gas space and liquid within its cuttlebone by an osmotic mechanism acting across the siphuncular surface of the bone. When the animal is at the bottom of the sea it would maintain the gas space within the cuttlebone by balancing the hydrostatic pressure of the sea by an osmotic force between the liquid within the cuttlebone and the blood.

In cuttlefish kept for some weeks in shallow water in an aquarium all the liquid taken from the cuttlebone is almost isotonic with the animals’ blood.

In animals recently hauled from the bottom of the sea the cuttlebone liquid is markedly hypotonic to sea water and hence to the blood.

These lower osmotic concentrations are given chiefly by reduction in the concentrations of the sodium and chloride ions.

After bringing animals up from about 70 m to the surface of the sea the osmotic concentration of the cuttlebone liquid rises from about 75% of sea water some 40 min after starting to haul the trawl, to about 97% of sea water 6 h later. Extrapolation back to the time at which hauling began gives a concentration of salts close to that predicted by the osmotic hypothesis.

Whilst the cuttlebone liquid is increasing in ionic concentration the liquid deeper in the cuttlebone is hypotonic to that just inside the siphuncular surface. This is explained in terms of the slowness of exchange of salts along the narrow channels between the lamellae of the cuttlebone.