bluuebunny/crossref_metadata_2025 huggingface dataset:
A Motographic Analysis of Foraging Behaviour in Intertidal Chitons (Acanthopleura Spp.)
Authors: Santini G. , Della Santina P. , Chelazzi G.
Published: May 2009

The behaviour of two intertidal chitons (Mollusca: Polyplacophora) from the western Indian Ocean (Acanthopleura gemmata and A. brevispinosa) and one from the Caribbean Sea (A. granulata) were analyzed in order to assess the spatial and temporal organization of their foraging activity. Individual paths were recorded in the field using a motographic method based on LED-tracking and the speed variation during each excursion used to reveal the places where the animals slowed down or stopped for the purpose of grazing. Foraging segments of each trajectory were selected according to a threshold speed which was individually calibrated. The three species of Acanthopleura exhibited graded foraging strategies of different spatial complexity. Acanthopleura gemmata focused its foraging on a few large feeding sites well separated from its permanent home. Acanthopleura brevispinosa exploited more subdivided feeding grounds not distinctly separated from its rest area. Acanthopleura granulata spreads its grazing activity over many small segments, throughout each excursion. Due to different tidal and diel constraints on their activity the three species allocated different absolute time to foraging, but the fraction of time spent foraging relative to the total excursion was similar in each.
Refugial Laminaria Abundance and Reduction in Urchin Grazing in Communities in the North-West Atlantic
Authors: Keats Derek W.
Published: May 2009

A literature review and new data are used to clarify geographical patterns of community response to release from heavy grazing by green sea urchins, Strongylocentrotus droebachiensis (O.F. Müller) within the north-west Atlantic region. Large geographical areas identified where urchin-removal experiments have not been conducted are the Passamaquoddy Bay area of the northern Bay of Fundy, the south and west coasts of Newfoundland, and southern Labrador. Within the north-west Atlantic region, there has been variation in the degree of domination by Laminaria species of post-urchin-removal communities. This is probably due, at least in part, to variation in the availability of Laminaria populations in refugia from urchin grazing. The following hypothesis is developed and given a preliminary test: in eastern Newfoundland, the absence of refugial Laminaria longicruris populations is due to periodic ice-scour. Despite the absence of significant Laminaria populations following short-term (<5 years) urchin-removal experiments in some areas, it is suggested that Laminaria spp. may be the natural, long-term community dominants in the absence of significant urchin grazing throughout the region. In view of the logistic problems involved in conducting long-term (6–15 years) urchin-removal experiments, it is suggested that urchin-removal/Laminaria-seeding experiments should be conducted within this region.
Amphipod Food Preference and Iridaeaspp. (Rhodophyta) Spore Release and Dispersal
Authors: Buschmann A. H.
Published: May 2009

Using laboratory experiments, this study examines the nature of the grazing relationship between the amphipod Hyale hirtipalma (Dana) and the red algae Iridaea spp., and the potential effects of grazing on the release and dispersal of algal spores. The results indicate that Hyale hirtipalma has a significant food preference for the cystocarpic stage of Iridaea laminarioides Bory when compared with consumption of Ulva rigida C. Ag. Hyale hirtipalma also shows a significantly greater food preference for cystocarpic tissues of Iridaea laminarioides and I. ciliata Kützing than for other karyological stages of these algae. By consuming the cystocarpic tissues, H. hirtipalma significantly increases the number of carpospores which are released and which settle at all measured distances from the mature cystocarpic I. laminarioides frond where measurements were taken. This evidence, together with information previously published, indicates that several Hyale species show similar food preferences towards the cystocarpic stage of Iridaea spp., and probably have the same ecological role as spore releasers and dispersal agents.
The Learning of Detours by Wrasse (Ctenolabrus rupestrisL.)
Authors: Spooner G. M.
Published: May 2009

1. This paper deals with certain experiments on training fish (Ctenolabrus rupestrisL.) to swim round obstructions to reach food, for the purpose of investigating how their learned response was developed. The whole question as to how learning which involves “problem-solving” is rightly to be interpreted and harmonized with our knowledge of conditioned responses, presents difficulties which have not yet been adequately faced.

2. A description is given of the results of experiments carried out on eleven fish. The fish had to learn a detour route either into a pot or round glass plates. Attention may be drawn to the great diversity in the behaviour of individual fish, both in their reactions to the obstruction at different stages of training, and in the method by which they succeeded in passing it. Some individuals are evidently more capable of profiting by experience than others.
A Review of the Amphipod Genus Corophium, with Notes on the British Species
Authors: Crawford G. I.
Published: May 2009

During 1934–5 I collected in Plymouth Sound and neighbouring waters seven species of the genus Corophium of which two were undescribed. I also collected one other species, and had sent to me two other species (one new) from other localities in South England. A list of these ten species, with the single other species known from Britain, is given in Appendix II, and their British distribution summarized.

In the course of identifying them I examined 23 of the 32 species of Corophium, and saw all the literature to which I could find references.
The Biology ofAporrhais pes-pelecani(L.) and A.serresiana(Mich.).
Authors: Young C. M.
Published: May 2009

1.Aporrhais pes-pelecanioccurs on muddy gravel at moderate depths and is specialized for burrowing in this.

2. The mode of burrowing is described and also the formation of mucuslined inhalent and exhalent openings by the proboscis.

3. There is a powerful respiratory current through the mantle cavity which also possesses three sets of ciliary currents for disposing of sediment carried in with this.

4. The animal is a specialized detritus feeder selecting only material of plant origin. The radula consists of one central and three lateral teeth on each side, an indication that it is used for seizing as opposed to scraping,notthat the animal is carnivorous.

5. The stomach possesses a well-developed ciliary sorting mechanism. The large crystalline style and gastric shield indicate that the animal is herbivorous, but there is no cellulase.
The Biology of Littorina littorea. Part I. Growth of the Shell and Tissues, Spawning, Length of Life and Mortality.
Authors: Moore Hilary B.
Published: May 2009

The Periwinkle, Littorina littorea (L.), is one of the most abundant gastropods on the shore, and can live under widely varying conditions. It is found on clean, alga-covered rocks, among small stones, on gravel, on soft mud, and rarely even on sand. It ranges from about high water of neap tides to extreme low water of spring tides, and in some places even slightly below this, although in most localities it is restricted to a much smaller part of the tidal zone. It occurs also from shores with high wave-exposure to sheltered and even polluted estuaries, where it is tolerant of considerable lowering of the salinity. The material for the present study was collected at intervals throughout 1934—1936 from three localities near Plymouth, the details of which are as follows.
Notes on the Culture of some Marine Plankton Organisms
Authors: Gross F.
Published: May 2009

The methods are described which made possible the establishment of pure cultures of a number of centric plankton diatoms and of the dinoflagellateProrocentrum micans.

By means of a modified technique cultures were obtained of some nannoplankton autotroph flagellates varying in size from 2 to 10u. Attention is drawn to their great number in the plankton and to their importance as food in the sea.

Herring, Angler and Pilchard larvae were reared for respectively 27, 29 and 15 days after hatching. The young Herrings and Pilchards fed onChlamydomonassp. andProrocentrum, the Anglers on nauplii ofArtemia salina. Some evidence is given for the conclusion that the ultimate failure in rearing these species was caused by too high and variable temperatures.
The lophophore and ciliary feeding mechanisms of the brachiopod Crania anomala (Müller)
Authors: Atkins D. , Rudwick M. J. S.
Published: May 2009

Orton's account of ciliary mechanisms on the lophophore of Crania anomala (Müller) is confirmed. Observations on the natural orientation of the lophophore have modified his account of the filter-feeding water currents. As in other brachiopods the lophophore divides the mantle cavity into inhalant and exhalant chambers with separate apertures to the exterior. The inhalant chamber has two apertures, is ventral in position, and extends into the interior of the spiral brachia; the exhalant chamber is dorsal in position and has three apertures. The development of the lophophore in the later growth stages is described. Both in development and in the form and function of the organ in the adult, the lophophore of C. anomala closely resembles that of the articulate species Tegulorhynchia nigricans (Sowerby): it is suggested that this reflects an inherent limitation on the possible variety of lophophores in brachiopods.
Comparative studies of luminescence in copepods and other pelagic marine animals
Authors: Clarke G. L. , Conover R. J. , David C. N. , Nicol J. A. C.
Published: May 2009

A comparative study of the following luminous copepods was undertaken: Metridia lucens, M. longa, M. princeps, Pleuromamma robusta, P. xiphias, Heterorhabdus norvegicus, H. robustus, Heterostylites longicornis, Lucicutia grandis, Hemirhabdus grimaldii, Disseta palumboi, Euaugaptilus magnus and Centraugaptilus horridus. Flashes produced by electrical stimulation (a.c. or condenser shocks) and mechanical stimulation were recorded photoelectrically. Flashes lasted from 2 to 37 sec. Latencies of some species (Metridiidae), following electrical stimulation, were very short, 7–9 msec. Intensities ranged from 0·02 × 10–5 to 14·4 × 10–5μW/s cm2 of receptor surface at 15 cm distance (0.0045 × 10–2 to 3·24 × 10–2μW/Cm2 at 1 cm) (10–20°C). Luminous glands of Metridiidae, Lucicutiidae and Augaptilidae are autofluorescent; the location of the luminous glands in these families and in Heterorhabdidae is described. Two kinds of glandular cells (types 1 and 2) occur in the luminescent areas. The cells are large saccular structures containing granular or homogeneous material, and are distinguished by staining peculiarities. Cell types 1 and 2 open through common pores, and may be the source of luminous reactants. Some measurements of luminescence in other pelagic animals are presented, for comparison with copepods, viz. Aequorea macrodactyla, Aeginura grimaldii (Hydromedusae), Periphylla periphylla (Scyphomedusa), Meganyctiphanes norvegica and Acanthephyra pelagica (Crustacea), Myctophum punctatum (Teleostei). Our present knowledge regarding luminescence among copepods is reviewed.
The life histories and population dynamics of monogenean gill parasites of Trachurus trachurus (L.)
Authors: Llewellyn J.
Published: May 2009

Gastrocotyle trachuri and Pseudaxine trachuri infect young Trachurus trachurus at Plymouth as soon as the 3- or 4-month-old adolescent fishes descend to the sea bottom in October. The parasites normally mature in 3 or 4 months, but, exceptionally, in about 1 month, and the life-span is normally no longer than 1 year. Trachurus specimens at the beginning of their second year pick up a largely new infection of parasites.

G. trachuri and P. trachuri are much less frequent on 2- and 3-year-old specimens of Trachurus and probably occur only very rarely on still older fishes, the limiting factor being not an age-immunity but a post-spawning migration of the host from the concentration of free-living infective stages of the parasites in coastal waters.

The parasites have adapted themselves to a seasonal change in the feeding habits of Trachurus by ceasing to produce larvae in anticipation of the summer disappearance of scad from the sea bottom in pursuit of pelagic food-organisms.
Spirorbis corallinaen.sp. and some other Spirorbinae (Serpulidae) common on British shores
Authors: De Silva P. H. D. H. , Knight-Jones E. W.
Published: May 2009

Spirorbis corallinaesp.nov. is very similar toS. borealisbut can be distinguished by its orange colour, small size, bifid opercular talon and particularly by the fact that the larvae choose to settle onCorallina officinalisrather than onFucus serratus.

Other species dealt with, in a key to identification and notes on distribution, areS. granulatus, S. malardi, S. pagenstecheri, S. rupestris, S. spirillumandS. tridentatus.
Nitrogen and phosphorus required for the growth of phytoplankton
Authors: Harvey H. W.
Published: May 2009

A method is described for obtaining growths of phytoplankton in samples of crude sea water, similar in composition but several hundred times more dense than phytoplankton communities occurring in the sea.

The ratio of nitrogen to phosphorus utilized by such communities has been determined.

They use ammonium in preference to nitrate, although the latter may be many times more concentrated than the former.

They use urea and uric acid as sources of nitrogen.

Certain amino-acids when added as sources of nitrogen were attacked by the bacteria in the community and either the ammonium set free or both the ammonium and the amino-acid were used by the phytoplankton. Others, asd-leucine, were not utilized, or, asl-leucine, only slowly utilized.

Sodium nucleinate and caseinate were rapidly broken down when added to crude sea water by bacterial action, and the phosphate produced utilized by phytoplankton. There was no significant utilization of glycerophosphate.
The larvae of the Pandalidae
Authors: Lebour Marie V.
Published: May 2009

Little is known of the larvac of the Pandalidac as is shown by Gurney (1939) in his Bibliography of the Larvae of Decapod Crustacea. Berkeley (1930,1938) describes the life histories of several species of Pandalus and of Pandalopsis dtspar from British Columbia, and Gurney (1937) the larvae and post-larvae of Chlorotocella, but beyond these the information is fragmentary. Sars’ (1900) work on Pandalus borealis and P. bonnieri was formerly regarded as typical of pandalid larvae but these were proved to be Caridion (Lebour, 1930). Sars (1900), however, described in part in an excellent manner the larvae of Pandalus montagui and Pandalina brevirostris and Stephensen (1935) the early larvae of Pandalus propinquus.
On the seasonal abundance of young fish. VII. The year 1939, January to August
Authors: Russell F. S.
Published: May 2009

In a number of previous reports observations on the seasonal abundance of the pelagic young of teleostean fish in the plankton off Plymouth have been recorded for the years 1924 to 1938 inclusive. Owing to the outbreak of war the series for the year 1939 is unfortunately not complete. Collections were, however, made until the last week in August. Previous records have always shown that the numbers of young fish caught in the last four months of the year, September to December, are insignificant and in consequence it is desirable that the results for 1939 should be published since they cover fully the period of production of almost all species of fish. It is, also, essential that these records should not be lost as the year 1939 has been the worst yet recorded and sets a new low limit to the production of fish. It is much to be deplored that the sequence of observations may be broken, so that we may never know what point the trough of the decline may reach.
The ecology of the Tamar Estuary VI. An account of the macrofauna of the intertidal muds
Authors: Spooner G. M. , Moore H. B.
Published: May 2009

The macrofauna of the intertidal mud-flats of the River Tamar have been investigated. Quantitative samples were taken by sieving the mud through a o·8 mm. sieve. Traverses of series of stations were worked at successive intervals up the river, and the tidal level of each station ascertained.

The characteristic species which inhabit the mud-flats are listed and the data secured regarding (1) population density, (2) up-river penetration, and (3) vertical distribution, are summarized and related to previous information on these points.

While some species are more or less uniformly distributed intertidally, others show marked zonation, with maxima in one part or another of the intertidal zone. Marine species which penetrate into the estuary tend to show the same intertidal distribution as in marine habitats. All five of the more strictly estuarine species are concentrated in the upper tidal levels.

In considering the limiting factors which cause a decrease of population at lower tidal levels, emphasis is placed on the probable importance of the increase in strength of water currents towards low water.
The osmotic relations of the plankton diatomDitylum brightwelli(West.)
Authors: Gross F.
Published: May 2009

During resting spore formationDitylumloses the cell sap and the volume of the resulting resting spore is one-third to one-twentieth of the cell volume.

Ditylum plasmolyses in 3·5–I.7% NaCl solutions, and in a few seconds the protoplast is reduced to the size and structure of a resting spore. In 0·5% NaCl there also occurs a considerable reduction in volume. The plasmolysed cells recover completely when removed into sea water. Rapid plasmolysis was also observed in isotonic and hypotonic dextrose and sucrose solutions and in solutions of CaCl2.
On changes taking place in sea water during storage
Authors: Harvey H. W.
Published: May 2009

The rapid growth of bacteria when sea water is stored in glass vessels, and the possibility that this is brought about by the concentration of food by adsorption on the solid surface, are discussed. Some evidence is presented bearing upon such adsorption.

The regeneration of phosphate from dissolved organic phosphorus compounds in the sea and in stored water is considered.
The ecology of some parasitic copepods of gadoids and other fishes
Authors: Sproston N. G. , Hartley P. H. T.
Published: May 2009

The migratory habits of Gadus merlangus and G. pollachius are examined n i relation to the variations in the rate of infection of these fish with Lernaeocera branchialis. A sudden increase in infection in estuarine and inshore waters is found to coincide with the offshore migration of the main stock. The infected fish apparently linger behind and may live for some time in the old habitats after the arrival of the next recruitment. The offshore migrants are seldom infected, and it is probable that infection does not take place in water deeper than about 5 fathoms.

The possible immediate causes of this “lingering” phenomenon are examined, and two suggestions are made as to the nature of the physiological upset brought about by the presence of L. branchialis on these gadoids. Other factors influencing the distribution of the parasite are discussed.

The relative susceptibility of the different species of gadoids to infection with species of Lernaeocera is examined as far as the data allow.
Observations on the bionomics and physiology ofTrebius caudatusandLernaeocera branchialis(Copepoda)
Authors: Sproston N. G. , Hartley P. H. T.
Published: May 2009

A study of the distribution ofTrebius caudatusfrom four species ofRajatrawled from two localities of different depths at Plymouth shows that there is a higher infection rate in the deeper water.

Both at Roscoff (France) and at Plymouth the mean total rate of infection is about 20%, and the larger fish are more often infected than the smaller. Both sexes are equally parasitized and the copepods tend to collect near orifices on both surfaces of the fish (regions where the mucus secretion is maximum). Immature forms were found at Roscoff in the mucus of the orifices themselves. The collections from both places contained about equal numbers of male and female parasites.

Intestinal respiration, a feature common to free living and parasiticcopepods, includes the gaseous exchange through the gut wall, the associated movements stirring the oxygen vector (which is either the external medium taken in by the anus, or the food current when this is the blood of the host), and the circulation of the body fluid as a direct result of these movements. The significance of the gut movements, which include the peculiar two-way peristalsis, is examined in detail inTrebius caudatus and Lernaeocera branchialis: the former has a functional anus which admits the external medium and the latter has a closed anus and employs the blood of the host as the oxygen vector.
Observations on the biology of Pandalina brevirostris [Decapoda; Crustacea]
Authors: Allen J. A.
Published: May 2009

The life-cycle of a population of Pandalina brevirostris living off the Northumberland coast is described. Most specimens were taken over sandy gravel or sandy mud with a covering of zoophytes in depths ranging from 20 to 30 fm. A very few specimens were taken over soft mud in 50 fm.

Eggs are laid during the period from January to the beginning of September. Females may lay two or possibly three broods in each breeding season. There is a period of 12–14 weeks between the laying of the eggs and the hatching of the larvae. The ova of those females that have a brood of eggs within the first half of the breeding season mature as the eggs develop, and are ready for laying following the release of the larvae. The adult P. brevirostris reaches maturity 8–12 months after hatching as a larva and lives on to breed again in the following season. They die at the end of their second breeding season. Thus, the probable life-span of the female is 24–30 months following its release as a larva, while that of the males is about 21–27 months.
The neuston net A device for sampling the surface fauna of the ocean
Authors: David P. M.
Published: May 2009

An apparatus for sampling the fauna of the uppermost 10 cm of the sea is described. The net is designed to fish at speeds of 5–6 knots in undisturbed water to one side of a ship. A preliminary account is given of the catches made with the net in the Indian Ocean.
Iron compounds in the heart-body of the terebellid polychaeteNeoamphitrite figulus
Authors: Dales R. Phillips
Published: May 2009

The heart-body contains haematins derived from by-products of haem synthesis. It also contains a non-haem iron protein and a flavin. Study of the relative amounts of these substances in worms of different ages and at different seasons suggests that the flavin plays some part in the metabolic activity of the organ and that the haematins accumulate throughout life. No evidence was found for the heart-body participating in any excretory activity or in haemoglobin breakdown.
On the nutrition and metabolism of zooplankton III. Nitrogen excretion byCalanus
Authors: Corner E. D. S. , Cowey C. B. , Marshall S. M.
Published: May 2009

Nitrogen excretion byCalanus finmarchicus(Gunnerus) andC. helgolandicusClaus collected at Millport and Plymouth has been measured under various experimental conditions.

Adult females feeding onBrachiomonas submarina, Cricosphaera elongataandSkeletonema costatumat cell concentrations corresponding to the mean annual level of particulate nitrogen in Plymouth Sound excrete 12·4, 9·0 and 6·4 μg N/mg dry body weight/day respectively. When the concentration of food is raised, as might occur during a spring outburst of phytoplankton, there is an increase in the quantity of nitrogen excreted. On the other hand, nitrogen excretion rapidly diminishes in the absence of food.
Preliminary observations on the fine structure of Prasinocladus marinus
Authors: Parke M. , Manton I.
Published: May 2009

The type species of Prasinocladus has been re-investigated in cultured material from the Devon coast and studied electron-microscopically by whole mounts and by sections. Salient findings include: the presence of two layers of scales together with characteristic hairs on all four flagella; the arrangement of the flagellar bases in a row, and of characteristic flagellar ‘roots’; the presence of an unusual condition of the pyrenoid with respect to the nucleus; and the structure and behaviour of the theca as different from that of an ordinary cell wall. It is concluded that the genus could appropriately serve as the type of a group to include all known genera and species of monads containing chlorophyll b that possess scaly flagella, but no recommendations are made as to whether the name Prasinophyceae (Christensen, 1962) should be restricted to these or be permitted to cover other known green flagellates lacking scales on their flagella. This investigation is continuing.
Three species of Halosphaera
Authors: Parke M. , Hartog-Adams I. Den
Published: May 2009

Two phases, cyst and motile, of three species of Halosphaera (Prasinophyceae), H. viridis Schrn., H. minor Ostenf. and H. russellii Parke, sp.nov., are described and the distinguishing characters tabulated. The stages in development of the two phases are detailed and a possible periodicity in their production is suggested. Only the motile phase can persist as an independent form reproducing asexually by fission. Sexuality is not recorded for the genus nor can the reported production of aplanospores be substantiated. The supposed ‘heterokont motile phase of Halosphaera’ of Pascher, who placed the genus in the Xanthophyceae, is believed to be a colourless phagotrophic flagellate parasitizing the cyst phase. All cyst phases, with plain or punctate walls, resembling those of Halosphaera in structure, do not necessarily belong to this genus. The study of living material is therefore essential.
The developmental stages of Lernaeocera Branchialis (Linn.)
Authors: Sproston Nora G.
Published: May 2009

The morphology of a complete series of developmental stages of Lernaeocera branchialis is described. Seven stages are passed through before reaching the gadoid (final) host.

The structure of the mouth tube and appendages is discussed in detail and compared with those of related genera in which the resemblances are close.

The free single nauplius and copepodid stages are immediately followed by four chalimus stages on Pleuronectes flesus; these show some dedifferentiation though segmentation is not lost. An explanation is given for the peculiar suspensory mechanism of the chalimus.

A second dedifferentiation follows the second well-developed pelagic phase in which the adult form is attained and copulation takes place. Some irregularity is noted in the details of the retrogressive metamorphosis of the maturing female on the gadoid host.

The rate of increase in body length in Lernaeocera decreases regularly up to the assumption of the adult form (stage VII). In this respect it is similar to the free-living copepods Diaptomus, Eurytemora and Calanus, but is in strong contrast to Caligus centrodonti which has an increasing growth rate up to the fourth chalimus stage. In the latter at this stage there is a marked acceleration in the growth rate unaccompanied by any change in shape or any other discontinuity, whereas in Lernaeocera there are early discontinuities in development, yet the growth rate is continuous when expressed graphically: it is a straight line rather than a logarithmic curve as would be expected from our knowledge of the higher Crustacea.

The size of the female is greater than that of the male: that of the female overlapping the male of the succeeding stage. Variations in size of the larvae in a stage group are not seasonal, and an explanation is offered for giant larvae.

Similar lernaeocerid larvae and males to those of Lernaeocera branchialis on Pleuronectes flesus were found on Solea solea and Cyclopterus lumpus. No characters of generic or specific significance could be found which would serve o t separate them from Lernaeocera branchialis so that their identity is not determined.
A study of a marine benthic community with special reference to the micro-organisms
Authors: Mare Molly F.
Published: May 2009

An attempt has been made to deal briefly but quantitatively with all size groups of the fauna and flora in a marine mud deposit.

It has been necessary to propose the following new terminology: theMacrobenthos, which is here equivalent to the macrofauna, theMeiobenthos, under which term are included copepods, nematodes, foraminifera, etc., and theMicrobenthos, comprising the rest of the protozoa, bacteria, bottom diatoms and other algae; planktonic diatoms and coloured flagellates also occur on the bottom in the region investigated but are not regarded as true microbenthos.

A quantitative ecological study of the microbenthos has been started and the habitat is first described, stress being laid on points of importance to the microorganisms.

The census method for bacteria was an agar-plate method and that for the protozoa and diatoms was a dilution culture method modified from that used by soil microbiologists.

These methods give minimal values for the total population and may safely be used for comparative purposes. The results are still tentative.

Typical figures for the minimal numbers and volumes of living protoplasm per gram of dry mud in the top ½ cm. layer are given in Tables I-IV.

The surface layer is much richer in all types of organisms than is the mud deeper in the cores. There is considerable local horizontal variation in numbers of bacteria and protozoa, suggesting dense aggregations.

Diatoms contribute by far the greatest bulk to the total volume of living micro-organisms; planktonic diatoms, particularly during the summer, completely outweigh the true microbenthos.
The displacement method of weighing living aquatic organisms
Authors: Lowndes A. G.
Published: May 2009

The method by which the weight, volume, density and sinking factor of living aquatic organisms can be determined has been extended. By sinking factor is meant the ratio of the density of the organism to that of its environment at the time of the actual determination. The density of the environment is always raised to 1000, and the density of the organisms computed on this basis.

A quick and accurate method for determining the percentage of water in a living organism has been described and discussed.

On the assumption that a sponge consists of protoplasm and spicules only, the density of the protoplasm has been computed.

The sinking factor of several fish and of the embryos of some Crustacea at different stages has been determined. One effect of the swim-bladder in teleost fishes is to reduce the sinking factor and thus facilitate swimming.

The effect of the sinking factor on swimming in general and the effects of spinous outgrowths in pelagic Crustacea are discussed.
Studies onPolystomellaLamarck (Foraminifera)
Authors: Jepps Margaret W.
Published: May 2009

Part I. After a brief statement of the present unsatisfactory position regarding the life history ofPolystomella crispa, an account is given of experiments with various fixatives onP. crispa, collected near Drake's Island, Plymouth. A method is described for the cultivation ofPolystomellain diatom cultures, especially withNavicula muticavar., with which a flagellate (Bodosp.) was constantly present. The identification of individual Foraminifera, and determination of growth, were often possible by some irregularity in the shell, or by noting the attachment of one or more stalked egg cocoons of an unknown turbellarian worm. The feeding ofPolystomellaon diatoms seized by the pseudopodia outside the shell is described; the structures previously taken for ingested algal cells inside the shell are shown to be foraminal plugs (‘bouchons’ of le Calvez) which are discarded from time to time and thrown out of the shell along with the excretory granules (xanthosomes), mostly via the canal system.

Part II. Notes are given on the microspheric form and its reproduction, through the spring and summer, by schizogony. The rearing of two broods in laboratory cultures is described, with an account of the formation of a new chamber to the shell. It is concluded that a complete life cycle consisting of one microspheric and one megalospheric phase occupies a period of about two years.

Part III. Sporulation of the megalospheric form is described as seen during life; and various factors are discussed which might affect the process. The relatively small size of the reproducingPolystomellawith which Lister worked is ascribed to their having lived under less favourable conditions. From a study of stained preparations, certain details are added concerning the opening up of the shell, presumably to facilitate the eventual escape of the flagellate swarm spores; also concerning the accompanying cytoplasmic and nuclear changes. Some account is given of the form and structure of the swarm spores, both alive and in permanent preparations. Experiments are described which constitute an attempt to carry the life cycle beyond the stage of sporulation. They are so far unsuccessful, with one possible exception, under all the various experimental conditions which are briefly discussed in their turn.
On the biology of the small copepods in Loch Striven
Authors: Marshall S. M.
Published: May 2009

The seven species of small copepod common in Loch Striven have been studied from vertical tow-net hauls taken there throughout the year 1933. These copepods were Pseudocalanus minutus, Paracalanus parvus, Microcalanus pygmaeus, Centropages hamatus, Temora longicornis, Acartia clausi and Oithona similis.

In general, the copepods began to reproduce about the time of the spring diatom increase in March or April, and produced a succession of broods throughout the summer; apart from the first these broods were not as a rule so clearly marked as in Calanus. Microcalanus begins to breed before the spring increase and has clearly marked broods like Calanus.
The Fauna of Sand and Mud Banks Near the Mouth of the Exe Estuary
Authors: Holme N. A.
Published: May 2009

Erosion of Dawlish Warren, at the mouth of the Exe Estuary has resulted in a redistribution of sand, which has come to lie in close proximity to certain of the original mud banks.

Quantitative collections of the macrofauna were made along a traverse passing from the newly deposited sand to the old mud bank, stations all being at about half-tide level.

Measurements of salinity, temperature, pH, currents and wave action show that these are similar for all stations. Thus it has been possible to observe the distribution of the fauna in relation to the type of soil without the usual complications due to differences in other factors.
Responses ofBranchiomma Vesiculosum(Montagu) to photic stimulation
Authors: Nicol J. A. C.
Published: May 2009

InBranchiomma vesiculosumdecrease in light intensity causes the animal to contract and withdraw into its tube. A decrease, never an increase, in illumination is the effective stimulus. When repeatedly stimulated the animals quickly become adapted to intensity changes and no longer respond.

The minimal effective intensity change has been determined for a range of intensities. ΔI/I is found to increase in low light intensities, and to be fairly constant in intensities over 50 lux. The animals are least sensitive to red light; sensitivity increases in shorter wave-lengths.
The British Edwardsidae
Authors: Carlgren Oskar , Stephenson T. A.
Published: May 2009

The genus Edwardsia is one known to most zoologists as an example of a primitive eight-rayed Zoantharian from which (or from a form resembling which) the higher forms are derived. It is only comparatively recently, however, that our knowledge of Edwardsias has become at all extensive, and even now it is incomplete; but it is desirable to produce a revision of the British forms since no adequate account of these exists.
The Life History of Thysanoessa raschii
Authors: Macdonald Roderick
Published: May 2009

Thysanoessa raschii is a regular inhabitant of the Firth of Clyde. Adults are found throughout this area, generally in waters not less than 40 fms. deep. Those of large size, 23–25 mm., are apparently consistently found from year to year in Loch Striven in large numbers from October to January within 10 fms. from the bottom in waters of 40 fms. depth. Throughout the rest of the year they occur in small numbers in the tow-nets, and are seldom found at all during the summer months. On one occasion, however, February, 1926, several hundreds were fished in addition to large numbers of Meganyctiphanes norvegica at 40–60 fms. in the Cumbrae Deep.
A Net for Catching Plankton near the Bottom
Authors: Russell F. S.
Published: May 2009

In the course of the researches on the vertical distribution of plankton it became evident that a net was needed for sampling the water-layers very close to the sea bottom. While the net had to be efficient in capturing the plankton animals present in those layers, it was necessary that the catches should not be vitiated by the presence of bottom-living organisms which had been stirred up from the sea floor by the net itself.
The Relationship between State of Maturity and Chemical Composition of the Whiting, Gadus merlangus L
Authors: Bull H. O.
Published: May 2009

In the whiting, no significant changes occur in the composition of the muscle substance, either throughout the year, or with increasing age, or during ripening of the gonads.

The amount of fat in the liver is very low in immature fishes, increasing greatly with age, and reaching its maximum just after the commencement of the ripening of the gonads. It then falls off, reaching its lowest value amongst mature fishes in the “Spent” stages. Males are richer in liver fat than females.

Immature fish have a decidedly higher protein content in the liver than have mature fish.
The Preservation of Fishing Nets by Treatment with Copper Soaps and Other Substances
Authors: Atkins W. R. G.
Published: May 2009

1. Under the conditions of the tests cotton and hemp nets became rotten in Aquarium tank water in two months or less in summer, in 4½–5½ months in winter.

2. A mixed copper soap, containing oleate, stearate, and palmitate, is as good, probably rather better, than is copper oleate as a net preservative.

3. “Cuprinol,” a petroleum acid copper soap, is better than the fatty acid soaps, both in fresh and in salt water. It is more than three times as expensive, however.
Herring Investigations at Plymouth. I. Methods of Collection and Treatment of Data
Authors: Ford E.
Published: May 2009

Towards the end of the year 1924, the present writer commenced a statistical study of random samples from commercial landings of herrings at Plymouth, in order to obtain information on the two following questions:—

(a) Upon what year-class or year-classes of herring was the season's fishery of 1924–25 concentrated?

(b) Did the fishes landed throughout that season appear to conform to a single morphological type?
Herring Investigations at Plymouth. III. The Plymouth Winter Fishery during the seasons 1924–25, 1925–26, and 1926–27
Authors: Ford E.
Published: May 2009

Although locally caught drift herrings may be landed at Plymouth from the end of September onwards until the beginning of March, the fishery only assumes economic importance during the months of December and January, when a large number of visiting drifters from both Cornwall and East Anglia are making daily fishing trips, using Plymouth as their temporary base.
Herring Investigations at Plymouth. IV. The Growth of Young Herrings in the Neighbourhood of Plymouth
Authors: Ford E.
Published: May 2009

Comparatively little has been published concerning the habitat and growth of young herrings in the English Channel, especially during the first year of their life. On May 26th, 1927, the first of a series of hauls with a small-meshed Saltash tuck seine (vide Davis, 1, p. 70, for a description of this type of net) was made in the River Tamar and a fine haul of young clupeoids obtained, which included the young of the herring, sprat and pilchard. Since then, regular samples have been taken from the rivers Tamar, Tavy and Lynher, and sufficient numbers of young herrings collected on each occasion to give a reasonable indication of the length-distribution prevailing. Sampling is still in progress and will be continued until one year's observation has been completed, but sufficient data are now to hand to merit an initial report. The localities from which the samples were obtained are indicated in the accompanying chart.
The Photosynthesis of Diatom Cultures in the Sea
Authors: Marshall S. M. , Orr A. P.
Published: May 2009

Photosynthesis in the open sea is due mainly to two groups of organisms, the diatoms and the dinoflagellates. In British seas the diatoms are so much more numerous that the chemical changes which are due to photosynthetic activity can be almost entirely ascribed to their influence. Recent work on these chemical changes has shown that they do not extend deeper than about 30 metres. Of the external limiting factors light is among the most important and the depth to which photosynthesis can go on must, of course, depend on the light intensity. In the study of the phytoplankton under natural conditions the results are complicated by the interaction of many other factors such as temperature, viscosity, or lack of food salts, so that it is difficult to come to definite conclusions on the effect of light alone.
On the Biology of Calanus finmarchicus, I. Reproduction and Seasonal Distribution in the Clyde Sea-Area during 1932
Authors: Nicholls A. G.
Published: May 2009

1. Fortnightly samples were taken with a fine-meshed net in single vertical hauls at different positions in the Clyde Sea-Area.

2. Each stage of Calanus present, from ovum to adult, was counted, and charts were constructed expressing these results for one year as total numbers and as percentage composition.

3. Calanus passes the autumn and early winter mainly in its Stage V copepodite form.

4. In general, total numbers were high in September, 1931, and fell steadily to a minimum in March; in Loch Fyne the minimum occurred i n April.

5. A sudden increase was observed in May and numbers rose to maximal values; the decline also was sudden.

6. Reproduction began in February and three plainly marked breeding periods were observed between February and July.

7. The time taken by the egg in developing into the adult was four weeks.

8. The total life of a Calanus during the summer was estimated to be about two and a half months; in winter it is five to six months.

9. In Loch Fyne a noticeable lag occurred during the winter and early spring.

10. The number of Calanus present in the autumn of 1932 was considerably less than.at the same time in 1931. This may have been due to a shortage of food.
On the Biology of Calanus finmarchicus. III. Vertical Distribution and Diurnal Migration in the Clyde Sea-Area
Authors: Nicholls A. G.
Published: May 2009

1. Previous work on vertical distribution and diurnal migration is described.

2. The diurnal migration of Calanus was studied on two occasions in Loch Fyne (January and July, 1932).

3. Vertical hauls were taken every three hours with a closing net dividing the total depth into six sections.

4. The results for each copepodite stage of Calanus are discussed, and January and July conditions are compared where possible.

5. Ova and nauplii were observed to be most abundant in the top 30 metres.

6. Copepodite Stages I, II, and III were most abundant above 30 metres and only the third copepodites showed any tendency to descend as the light increased.

7. Stage IV showed a migration towards the surface at night, but were generally distributed during the next day.

8. It is suggested that the results for this stage are probably confused owing to its transitional nature between the young stages living at the surface and Stage V Calanus living in deep water.

9. Stage V was found always in deep water, slight diurnal changes being ascribed to the presence of such Calanus as were about to moult into adults.

10. Females showed definite diurnal migration in both January and July.

11. Males showed a general distribution and migrated in small numbers towards the surface at night and away from it during daylight.

12. Stage V copepodites and females both lived nearer the surface in January than in July, correlated with seasonal changes in the intensity of the sunlight.

13. The presence of swarms of Calanus at the surface under conditions of bright sunlight is discussed.
The Littoral Diatoms of the Liverpool and Port Erin Shores
Authors: Ghazzawi F. M.
Published: May 2009

Certain diatoms seem to live predominantly on the foreshore. While the pelagic diatoms have received very much study, relatively little attention has been given to the shore forms. There is no satisfactory account of these organisms as they occur on the coasts of Lancashire and Isle of Man, and one may expect that they have much importance as the food of many animals. In a further paper I will deal with this question. For this reason I deal here only with those littoral diatoms found along the Mersey Beach, in the vicinity of Liverpool, and with those collected from the sandy and rocky shore of Port Erin (Isle of Man). Masses of these organisms can easily be recognised with the naked eye, discolouration of the sand and mud being due mainly to them, together with some species of desmids and dinoflagellates.
On the Marina Cladocera from the Northumbrian Plankton
Authors: Jorgensen Olag M.
Published: May 2009

From an analysis of previous records of E. nordmanni, considered in conjunction with those furnished by the present investigation, the following points of interest emerge.

1. E. nordmanni, while being generally distributed in the North Sea and adjacent waters throughout the summer months, has been shown to breed freely in inshore waters in early summer and again in autumn when maximum numbers of individuals are obtained.

2. These two periods of maximal abundance are produced as the result of successive parthenogenetic broods and alternate with periods of depression. This is indicated not only by the sexually-produced winter-egg, but also by a reduction in the number of embryos contained in the brood chamber and consequent change in body-shape. This serves to show that the supposedly distinct races, described as being characteristic of the North Sea and the Baltic, have no doubt been founded on material taken at different periods of the agamic phase.
Studies on the Monogenea of Plymouth. Gastrocotyle trachuri v. Ben. and Hesse, 1863
Authors: Jones E. Idris
Published: May 2009

In August, 1932, six specimens of this species were found on the gills of Trachurus [Caranx] trachurus taken at Plymouth. This is the first record of its occurrence in British waters.
Rhopalura granosasp. nov., an Orthonectid Parasite of a LamellibranchHeteranomia squamulaL., with a Note on its Swimming Behaviour
Authors: Atkins D.
Published: May 2009

A new species of Orthonectid,Rhopalura granosafromHeteranomia squamulaL., is described. The female is fusiform, and about 190 to 230μ, long, and 55 to 75μ broad. The male is also fusiform, but less than half the size of the female, being only 87 to 95μ, long and 20μ broad.R. granosais distinguished from all other known species of Rhopalura by the presence in the male of large refringent bodies in the anterior cone, and in the first row of cells of the second ring. The male ofR. ophiocomceGiard, a species closely allied toR. granosa, has the refringent bodies in the cells of the second ring only.