bluuebunny/crossref_metadata_2025 huggingface dataset:
Experiments on the tidal rhythm ofBlennius pholis
Authors: Gibson R. N.
Published: May 2009

The endogenous tidal rhythm of the littoral fishBlennius pholisL. was studied in the laboratory. It was found that there was no difference in the mean level of activity of fish caught on spring and neap tides. The time-interval between activity peaks (the period length) gradually increased in constant darkness. A similar, although not significant, increase was also observed in continuous illumination.

There was no evidence of any diurnal component in the rhythm, but freshly caught fish subjected to alternating periods of light and darkness, equal in duration to the natural period, responded to the onset of illumination by greatly increased activity only when the light period began between activity peaks.

Fish which had been kept in the laboratory for several weeks and had lost their natural rhythm still responded to light by increased activity. This increase was not as great as that shown by freshly caught fish, however, and the response decreased with time. Evidence of re-entrainment of the natural rhythm after 7 days in alternating periods of light and darkness was not found. It was shown that feeding the fish half-way through the 12 h light-period resulted in a reduction of activity after feeding. This did not occur when the fish were fed half-way through the dark period.

A 4h cold shock of 10° C resulted in partial re-entrainment of rhymthic activity inB. pholis.

B. pholis, which alone appears to have a persistent rhythm, differs from certain other fish examined in its strictly littoral habitat and its possible need for activity periods synchronized with the tide.
Biochemical differences betweenCalanus finmarchicusandC. helgolandicusEsterases, malate and triose-phosphate dehydrogenases, aldolase, ‘peptidases’, and Other enzymes
Authors: Manwell Clyde , Baker C. M. Ann , Ashton P. A. , Corner E. D. S.
Published: May 2009

Three species of copepods—Calanus finmarchicus(Gunnerus),C. helgolandicus(Claus) andC. hyperboreus(Krcyer)—can be easily and consistently differentiated by starch-gel electrophoresis of a number of their enzymes. The techniques used allow the study of individual variation in natural populations of small invertebrates, some of the variation being readily equated with known genetically based protein polymorphisms in man and other species.C. finmarchicusandC. helgolandicushave 15 enzyme zones in common and differ by 24-28 zones. By the rationale of molecular biology it can be suggested that these two forms differ in two-thirds of the structural genes. The results support the morpho-logical studies by Rees (1949) and Matthews (1966b) and the chromosomal studies by Harding (1963). Hence it is clear that the‘finmarchicus-helgolandicus’problem is solved:C. finmarchicusandC. helgolandicusare distinct species. The potentials and problems of biochemical systematics are discussed with particular reference to marine biology.

INTRODUCTION

Electrophoretic techniques have contributed to the solution of many taxonomic problems—for example, the monophyletic origin of ratite birds (Sibley, 1960), the discovery of a sibling species of sea-cucumber (Manwell & Baker, 1963 a; Manwell, 1966a), the status of species and populations of pheasants (Baker, 1965; Baker, Manwell, Labisky & Harper, 1966), the union of the orang-utan, chimpanzee, gorilla and man into one family, the Pongidae (Tashian, 1965), and the recognition of hybridization in lizards (Dessauer, Fox & Pough, 1962) and fishes (Manwell, Baker & Childers, 1963).
On the buoyancy of Spirula spirula
Authors: Denton E. J. , Gilpin-Brown J. B. , Howarth J. V.
Published: May 2009

Spirula spirula (L.) when freshly caught was found to be close to neutral buoyancy. The pressure of gas within the chambers of the shell was always less than atmospheric, being very low in the newest chamber of a growing animal and rising to a value a little below atmospheric in the older chambers. A chamber which was being formed was completely full of liquid. The only connexion between the liquid in a chamber and the living siphuncle is through a small permeable region of the siphuncular wall which lies at the top of a newly formed chamber. These results support the hypothesis that Spirula, Nautilus and Sepia all regulate their buoyancy in the same way. The shell is sufficiently strong to withstand the hydrostatic pressure of the sea at the depths at which the animal lives.
Environmental Tolerances of Three Species of The Harpacticoid Copepod GenusTigriopus
Authors: Davenport J. , Barnett P.R.O. , McAllen R.J.
Published: May 2009

The harpacticoid copepod genusTigriopusis characteristic of shallow upper shore rock pools in both hemispheres.Tigriopusare necessarily physiologically tolerant as the pools feature extreme physicochemical conditions; their lower limit on the shore is apparently set by competition/predation. There are several species, differentiated by relatively minor morphological distinctions; speciation appears to be favoured by restricted gene flow between populations, even over short distances. This paper briefly reviews the literature concerned with the taxonomy, physiology and ecology of the genus, and compares environmental conditions and salinity/thermal tolerance data for three species: T.brevicornisfrom Scotland, T.fulvusfrom Madeira, and a previously undescribed population of the Southern Ocean ‘T. angulatus’ group from subantarctic South Georgia. Particularly interesting was a low upper lethal temperature in‘T. angulatus’(21·9°C) that probably restricts the species to relatively large pools that buffer environmental thermal extremes. Unlike the other species,T. fulvuscannot withstand freezing conditions. Evidence is presented to show that the South GeorgianTigriopusdiffers slightly, but significantly, in its morphology from two sibling species that inhabit the subantarctic Kerguelen and Crozet Islands but which cannot interbreed. If the South Georgian copepods are indeed a separate species and do not occur elsewhere (e.g. the Falklands), this indicates rapid speciation within the genus; the coasts of South Georgia were covered by an icecap until 10,000–14,000 years ago and no rock pool habitats were then available. It is suggested thatTigriopusmay have reached South Georgia by rafting withinEnteromorphatubes.
Coupling of Environmental and Endogenous Factors in the Control of Rhythmic Behaviour in Decapod Crustaceans
Authors: Aréchiga Hugo , Rodríguez-Sosa Leonardo
Published: May 2009

Behavioural patterns of crustaceans are known to vary within the 24 hour cycle and in relation to environmental signals. Light and chemical stimuli induce specific behavioural responses. Retinal and extra-retinal photoreceptors use different motor responses to illumination selectively. Light responsiveness is modulated at various levels, from the light admittance to the retina, up to the integration in higher order interneurones and motorneurones. An endogenous circadian rhythmicity contributes to the various elements of the system.
Influence of Food and Predatory Attack on Mysid Swarm Dynamics
Authors: Ritz D.A. , Osborn J.E. , Ocken A.E.J.
Published: May 2009

Using video and image analysis techniques we analysed the response of swarms of the mysid Paramesopodopsis rufa to food and predatory attack. After food was added to the tank, mysid aggregations initially (up to 45 s) increased in volume. Subsequently volume decreased significantly until it was smaller than the initial level. After a period of ~12 h during which no food was added, the swarm expanded to near its original volume. These changes are interpreted as resulting from a need by individuals to optimize food capture and protection. The pattern of volume changes in response to food was independent of aquarium size but the magnitude of the changes was reduced in a smaller tank.

Predatory attacks on mysid swarms were simulated using a model fish which ‘swam’ a single pass along the tank driven by an electric motor. Models (latex-covered real preserved fish), represented two different attack styles: ambush (seahorse Hippocampus abdominalis); and lunging (Australian salmon Arripis trutta). ‘Swimming’ speeds resembled those measured for real fish i.e. 0·5–2·0 cm s-1 for seahorse and 15 cm s-1 for salmon. Again changes in swarm volume were recorded. No obvious response by the swarm to the approaching seahorse was apparent; the aggregation simply parted to allow the fish through. No tailflips were seen among the mysids. The swarm resumed the original volume rapidly after the fish had passed. Approach of the salmon was evidently detected from further away, escape reactions were frequent and energetic, and tailflipping was common. After the fish had passed, it took longer for the original swarm volume to be restored. These results suggest that seahorse ambush techniques have evolved to minimize warning of the predator's approach. When the salmon ‘menaced’ the swarm at seahorse speeds, it appeared the mysids still reacted as though it was a ‘normal’ salmon attack so the fright response was not just a function of speed of attack.

Dynamic changes in swarm volume seem to be a useful simple index of motivational state of individuals.
Ecology and Taxonomy of the GenusEurydice(Isopoda: Cirolanidae) From Sand Beaches on The Iberian Peninsula
Authors: Jones D.A. , Pierpoint C.J.
Published: May 2009

Quantitative sampling for the genusEurydice(Isopoda: Cirolanidae) was conducted on 25 sand beach sites along the Atlantic coast of the Iberian Peninsula. Five species were recorded intertidally:Eurydice affinis, E. pulchra, E. naylorisp. nov.,E. lusitaniensissp. nov. andE. spinigera. Physical data collected were used to construct an index of exposure to rank each site. The distribution of intertidalEurydicesp. is described in relation to exposure to wave action and to tidal level. Peak abundance ofE. affinis, E. pulchraandnaylorioccurred most frequently between mean high water neap (MHWN) and mean tide level (MTL). WhilstE. affinisoccurred over a wide range of exposure,E. nayloriexhibited a marked preference for exposed sites andE. pulchrawas only recorded from sheltered and semi-exposed sites. Surf plankton collections revealed the presence ofE. lusitaniensis, but as only two specimens were collected, its ecology remains unknown. The zoogeographical distribution of the genus on North Atlantic and Mediterranean coasts is briefly reviewed.
Crustacean Models for Studying Calcium Transport: The Journey from Whole Organisms to Molecular Mechanisms
Authors: Wheatly Michele G.
Published: May 2009

The crustacean moult cycle is a convenient model system in which to study calcium (Ca) homeostasis as vectorial movement across Ca transporting epithelia (gills, gastric epithelium, cuticular hypodermis, antennal gland) which occurs in either direction at different stages of the moulting cycle. Intermoult crustaceans are in relative Ca balance. During premoult, at the same time as the cuticle decalcifies, epithelia involved in Ca storage (e.g. gastric) calcify and/or increase their intracellular Ca stores. Premoult Ca balance is typically negative as Ca is excreted. During postmoult the soft new cuticle is remineralized largely with external Ca taken up across the gills and gastric epithelium (positive Ca balance); conversely during this time internally stored Ca is remobilized. This review (1) compares the relative roles of Ca transporting epithelia in Ca balance for crustaceans from different habitats; (2) proposes up-to-date cellular models for both apical to basolateral and basolateral to apical Ca transport in both noncalcifying and calcifying epithelia; (3) compares kinetics of the Ca pump and exchanger during intermoult; (4) presents new data on specific activity of calcium adenosinetriphosphatase (Ca2+ATPase) during the moult cycle of crayfish and (5) characterizes a partial cDNA sequence for the crayfish sarcoplasmic reticular Ca2+ATPase and documents its expression in gill, kidney and muscle of intermoult crayfish. The physiological and molecular characterization of Ca transporters in crustaceans will provide insight into the function, regulation and molecular evolution of mechanisms common to all eukaryotic cells.
Haemocyanin Oxygen Transport inOcypodeSpp.: Modulation of Oxygen Affinity?
Authors: Bridges C.R. , Hupperts V. , Eshky A.A. , Taylor A.C.
Published: May 2009

The present study confirms the findings that in the two ocypodid crabsOcypode saratanandO. ryderihaemocyanin oxygen affinity is increased in ‘replaced’ or dialysed blood compared to whole haemolymph and that this difference can be attributed to a plasma factor. After the replacement of the plasma, the haemocyanin of both species showed up to a 39% increase in oxygen affinity. The change in oxygen affinity was proportional to the logarithm of the amount of native plasma present. Further investigations have shown that this difference is not due to changes in plasma urate or bicarbonate concentrations. Using plasma exchange experiments it could be shown that the factor acts specifically on the haemocyanin ofOcypodespp. and not onCarcinus maenashaemocyanin. Fast protein liquid chromatography (FPLC) techniques indicate that the molecular weight of the factor is <5000 daltons and a specific peak could be isolated. This isolated peak is linearly correlated with changes in haemocyanin oxygen affinity. The results are discussed in the light of the overall modulation of haemocyanin oxygen affinity and the need for negative effectors.
Digestive Protease Activity in Planktonic Crustaceans Feeding at Different Trophic Levels
Authors: Kumlu M. , Jones D.A.
Published: May 2009

Trypsin-like enzyme activity of the larvae of two planktonic predatory crustaceans, Homarus gammarus and Nephrops norvegicus (Decapoda: Nephropidae) and the omnivorous larvae of Carcinus maenas (Decapoda: Brachyura) were investigated at each larval stage until metamorphosis. Two copepods, herbivorous or omnivorous grazers, Centropages typicus and Temora longicornis (Copepoda: Calanoidae) were also investigated for this enzyme. A comparison of trypsin-like activity in these and other decapod larvae shows a pattern with high levels in herbivores, low levels in carnivores and intermediate levels in omnivores. Herbivorous planktonic crustaceans appear to rely on high digestive enzyme activities to extract nutrients from less digestible algae or particulates, whereas carnivorous larvae have limited enzymatic capacity as they feed at higher trophic levels upon large and easily digestible prey. Omnivorous Carcinus maenas larvae have intermediate levels of digestive enzymes and are able to transfer between herbivorous and omnivorous feeding.
Ferritin Crystals in the Gut Caeca of a Deep-Sea Hydrothermal Vent Stegocephalid (Crustacea: Amphipoda)
Authors: Moore P.G. , Rainbow P.S.
Published: May 2009

Ferritin crystals and calcium granules are reported from the ventral ceaca of Steleuthera ecoprophycea (Amphipoda: Stegocephalidae) collected from the Snake Pit hydrothermal vent, Mid-Atlantic Ridge (3520 m).

In a series of earlier papers (Moore & Rainbow, 1984, 1989, 1992; Moore et al., 1994), the authors described the widespread occurrence of intracellular, octahedral crystals of ferritin in the ventral caeca of a range of stegocephalid amphipod species from the continental shelf epibenthos and oceanic plankton. The discovery at 3500 m of a new Steleuthera species (S. ecoprophycea), from a hydrothermal vent on the Mid-Atlantic Ridge was announced recently by Bellan-Santini & Thurston (1996), and a complete description is provided therein.

Oceanic ridge sites are notable for their tectonic activity and the presence of a diversity of trace metals at high concentrations is to be expected in hydrothermal plumes emanating from such regions (German & Angel, 1995). The detoxification of accumulated trace metals in the ventral ceaca of stegocephalid amphipods from uncontaminated environments is now relatively well known (see above), so it was of interest to investigate whether a vent stegocephalid showed an atypical presence of trace metals in detoxified form in cells of the ventral caeca. The results following from an opportunity to investigate this are reported herein.

Material was derived from a dive made by the submersible ‘Alvin’ at Snake Pit hydrothermal field, Mid-Atlantic Ridge (23°23′N 44°56′W), 3520 m, on 16 June 1993 (see Bellan-Santini & Thurston, 1996). Steleuthera ecoprophycea was preserved in 70% alcohol. Subsequently to dissection, the single pair of ventral caeca from each of the four damaged amphipods investigated were post-fixed in 4% glutaraldehyde. For electron microscopy and x-ray microanalysis in STEM mode, ventral caecal tissues were then dehydrated through 95% and absolute ethanol, cleared in propylene oxide, embedded in TAAB resin, sectioned at 0·5 μm (semi-thin sections) on a Reichert OmU2 ultramicrotome and examined without staining in a JEOL 100C electron microscope equipped with LINK system EDX energy dispersive x-ray microanalyser.
Activity Rhythms Of The Squat Lobsters, Galathea Squamifera And G. Strigosa (Crustacea: Decapoda: Anomura) In South-West Ireland
Authors: De Grave S. , Turner J.R.
Published: May 2009

This short note describes the in situ activity cycles of Galathea squamifera and G. strigosa (Crustacea: Decapoda) through SCUBA diving observations in south-west Ireland. Both species exhibited nocturnal activity peaks, although they were not exclusively nocturnal. Fluctuating tidal current strength and direction had no discernible influence on either species’ activity cycles. It is suggested that shelters, particularly in terms of both predator avoidance and as foraging areas, play an important role in the ecology of both species.

Both the anomuran decapod crustaceans Galathea squamifera Leach and G. strigosa (L.) are widespread throughout the rocky subtidal of the north-west European coastline. In contrast to the general body morphology and the structure of the mouthparts which have been well studied (Nicol, 1932; Pike, 1947), the biology and ecology of the genus Galathea remains poorly studied. These morphological studies have shown that the mouthparts are ill-adapted to living on muddy substrates, essentially restricting the distribution of both G. squamifera and G. strigosa to rocky areas, where their food is obtained by detrital deposit feeding and scavenging. Turner & Warman (1991) have studied the activity patterns of the genus Galathea at Lough Hyne, southwest Ireland and concluded that the genus exhibits nocturnal activity peaks. However, the different species were not distinguished, nor was the potential effect of the aberrant tidal patterns in the area considered. As at least three species (G. squamifera, G. strigosa, G. intermedia) are known to occur at the study site (Holmes, 1985), the present study was initiated to elucidate the activity cycles at a species-specific level.
Circatidal Moulting Rhythm in The Shore Crab Carcinus Maenas
Authors: Abello P. , Warman C.G. , Naylor E.
Published: May 2009

Late premoult females from precopula pairs of male and female Carcimts maenas (Crustacea: Brachyura) moulted at times of expected high tide in constant conditions in the laboratory. The data presents for the first time evidence of endogenous, circatidal (−12·4 h) moulting rhythms in a crustacean.

Studies on the temporal patterns of moulting in crustaceans have elucidated rhythms of seasonal (annual or biannual), lunar (29·4 d), semilunar (14·7 d) and diel (24 h) periodicities (see Conan, 1985; Fernandez et al., 1994). Examples in the literature of so-called ‘tidal’ rhythmicity of moulting given by Conan (1985) are more correctly referred to as semilunar or neap/spring patterns. There appear to be no reported examples of true tidal (12·4 h) moulting rhythms. Also there is very little evidence in the literature that moulting rhythms phased to geophysical cycles are controlled endogenously. Most studies have been carried out in the field or under L:D cycles in the laboratory and only a few have been undertaken with animals in constant conditions (see Fowler et al., 1971; Bishop & Herrnkind, 1976; Nicol, 1989; Fernandez et al., 1994). Conan (1985) has reported moulting rhythms of circamonthly, circatidal (=circasemilunar) and circadian periodicities but his use of the prefix ‘circa’ is unusual since it more correctly describes free-running rhythms in constant conditions, not environmentally driven rhythms as in the examples quoted. In the present study we sought to determine whether moulting in the shore crab Carcimts maenas (L.) was tidally patterned and endogenous.

Over a period of several days in the summer of 1991 large numbers of premoult female Carcinus maenas were obtained by searching for specimens associated with males in precopular pairs.
On different methods available for measuring the area of gill secondary lamellae of fishes
Authors: Hughes G. M.
Published: May 2009

Advantages and disadvantages of methods used to estimate area of individual secondary lamellae are discussed. Particular attention is given to explain the method which regards filaments as triangles and lamellae as rectangles. Dangers of some injection methods assuming that the whole lamellar microcirculation is equally involved in gas exchange are also emphasized. It is concluded that there is a need for comparisons of results when different methods are applied to the same material.
A comparative study of the anatomy and behaviour of the oncomiracidia of the related monogenean gill parasitesKuhnia scombri, K. sprostonaeandGrubea cochlearfrom mackerel,Scomber scombrus
Authors: Whittington Ian D. , Kearn Graham C.
Published: May 2009

The anatomy and behaviour of the oncomiracidia ofKuhnia scombri, K. sprostonaeandGrubea cochlear, related mazocraeid monogeneans from the gill chamber of the mackerel,Scomber scombrus, caught off Plymouth are compared.K. sprostonaeandG. cochlearare new records at Plymouth. The most important anatomical difference between these larvae is that those ofKuhniaspp. possess a pair of pigment-shielded eyes which are lacking in G.cochlear. The freshly hatched larvae ofKuhniaspp. are strongly photopositive but this response wanes after about 1 h inK. scombriand 1–5 h inK. sprostonae. No response to light was detected in larvae of G.cochlear. Most older larvae ofKuhniaspp. and of G.cochlearswim continuously upwards and downwards, even in ‘darkness’, indicating an alternation between positive and negative geotropism. The larvae ofKuhniaspp. possess angular cells (?) of unknown function close to the pharynx. The larvae of all three species contain prominent anterior glands and lipid droplets; the latter are depleted during their long free-swimming lives (up to 36 h inKuhniaspp. at 13–14°C).
Variations in the reproductive cycle of Acrocnida brachiata (Echinodermata: Ophiuroidea) according to environment in the Bay of Douarnenez (Brittany)
Authors: Bourgoin A. , Guillou M.
Published: May 2009

The annual reproductive and somatic cycles of the brittlestar Acrocnida brachiata are described using gonad and gut indices for intertidal and subtidal populations in the Bay of Douarnenez, France. Oocyte size frequency diagrams complement the gonad study in the subtidal population. Clearly marked reproductive cycles are defined in both populations. Accelerated gonad growth takes place in spring and the gonads reach the peak of development in May-June each year. Spawning is completed by the end of August. Oocytes reach a mean diameter of 150 μm and a new generation of oocytes appaears in the ovaries during the spawning period. The gut indices show a clear inverse relationship with the gonad indices in the intertidal population, but this relation is not well revealed in the subtidal population.
Structure and density of Haliotis tuberculata populations around the coasts of Jersey, Channel Isles
Authors: Peck Lloyd S. , Culley Michael B.
Published: May 2009

Haliotis tuberculata L. densities and population distributions were assessed for 13 sublittoral sites around the coasts of Jersey, Channel Isles using SCUBA techniques. Twenty 1 m2 quadrats were assessed at each site at 5 m below lowest spring tide level (LSTL). Mean densities at each site ranged from 0·05 animals m−2 to 2·35 animals m−2, while the overall mean for the whole island was 0·79 animals m−2 (s.e.=0·24). Population density (D) declined with increasing mean animal length (LTH). The slope of the equation relating loge D to loge LTH was -6·92. Data collected at 2 m, 5 m, 8 m and 10 m below LSTL at two sites showed no trend in mean animal length with depth at one of the sites, but it did increase slightly with depth (1·3 mm nr−1) at the other.
Factors affecting individual body weight in field populations of the mudsnail Hydrobia ulvae
Authors: Morrisey Donald J.
Published: May 2009

Differences in average body size among allopatric and sympatric populations of hydrobiid mudsnails have been interpreted as the consequence of interspecific competitive interactions. Recently, however, doubts have been expressed concerning the certainty with which size differences can be ascribed simply to character displacement. Other environmental factors are known to influence body size in hydrobiids. In the present study one of these, sediment type, was investigated.

Average body weight of Hydrobia ulvae (Pennant) living on fine mud was consistently higher than that of members of the same species living on adjacent muddy sand. Snails were transplanted from one sediment type to the other, confined within cages, and their growth rates compared with those of control animals caged on their native sediment. The results of this experiment suggested that substrate type is one factor controlling body size, but the inconclusive nature of the results indicate that others are also involved.
Physiological factors causing natural variations in acoustic target strength of fish
Authors: Ona E.
Published: May 2009

The swimbladder is recognized as responsible for a major part of the acoustic backscattering from fish. In most fishes it has the function of a buoyancy regulator but in others its main function is rather unclear. Based on methods for exact mapping of the swimbladder shape, observations of deviations from normal appearance and shape are discussed in relation to possible effects on target strength. Evidence for both periodic variations, as from uncompensated vertical migrations, and seasonal variations, caused by the fat cycle and gonad development, are presented.
Reproduction and life history strategy of the hermit crab Pagurus bernhardus
Authors: Lancaster I.
Published: May 2009

Hermit crabs use gastropod shells to protect their bodies and developing eggs; an inadequate supply of shells of the appropriate size will, therefore, adversely affect their growth, fecundity and longevity. Since the supply of shells is commonly limited, mechanisms that help to reduce these adverse effects will be selectively advantageous. In Pagurus bernhardus it is suggested that two mechanisms have evolved in this respect: larval settlement is encouraged in the littoral zone where gastropod species are diverse and numerous and where the youngest hermits will find growth potentially unrestricted; and females breed within their first year of life and at a size substantially below that which could be attained in the shells commonly available to them. This ‘precocious’ breeding is suggested to be an adaptation enabling hermits to overcome the problems of shell-limitation, since it frees females of the need to attain a specific age or size before reproducing - a situation which would be perilous when large shells are scarce. Males of a similar age are freed from competition for the larger shells as a result of this strategy, since the growth of the females is suppressed while they are ovigerous.
The energetics of migration by selective tidal stream transport: an analysis for plaice tracked in the southern North Sea
Authors: Metcalfe J. D. , Arnold G. P. , Webb P. W.
Published: May 2009

Adult plaice(Pleuronectes platessaL.) in the southern North Sea use selective tidal stream transport to migrate between their summer feeding grounds and winter spawning grounds. The fish come up into midwater when the tidal stream is flowing in one direction, but remain on the bottom when it is flowing in the opposite direction. This behaviour can theoretically save energy, which can be used for growth or reproduction. Alternatively, it may provide a transport system by means of which fish that have no ability to navigate over long distances can be conveyed reliably between their feeding grounds and spawning grounds.
Changes in lipids during simulated herbivorous feeding by the marine crustaceanNeomysis integer
Authors: Bradshaw Stuart A. , O'Hara Sean C. M. , Cornert Eric D. S , Eglinton Geoffrey
Published: May 2009

A laboratory study simulating herbivorous feeding was carried out with the marine crustaceanNeomysis integer(Leach) and the dinoflagellateScrippsiella trochoidea(Stein). Analyses of the total fatty acids, sterols and fatty alcohols in the food and faecal material, and in the animal tissue, have allowed the detailed changes in the dietary lipids during feeding to be characterised.

The results show this feeding leads to a net decrease in total lipid in the material passing through the gut of the animal, particularly due to the bioassimilation of fatty acids. All fatty acid saturation classes are assimilated but the mono-unsaturated and particularly polyunsaturated fatty acids are preferentially assimilated over others. Herbivorous feeding does, however, lead to the quantitative and relative increase in ‘bacterial’-type odd C number branched-chain fatty acids in the faecal material.
Organic content of the molluscan shell
Authors: Rodhouse P. G.
Published: May 2009

In a recent paper (Goulletquer & Wolowicz, 1989), data are presented which show that determination of the organic content of mollusc shells by weight loss on ignition may over-estimate this component by a factor of 2·5 to 4·8. They then go on to conclude in their discussion that Rodhouse et al. (1984) had over-estimated the organic content of Mytilus edulis shells by a factor of 2·5 through combustion at 540°C.
The uptake of gold by marine sponges
Authors: Bowen H. J. M.
Published: May 2009

Gold has been determined in six marine sponges by neutron activation analysis. The amounts found (1·8–12·6 × 10−8 g/g dry sponge) are higher than would be expected from measurements of the distribution of 198Au between sea-water and dead sponge samples.

Many attempts have been made to devise methods for concentrating gold from sea water, but none of them are commercially viable. Recent work has shown that gold can be concentrated by adsorption or absorption on certain artificial polymers (Hummel, 1957; Bowen, unpublished). This note describes some measurements of the accumulation of gold by marine sponges whose scleroprotein structure resembles some of the artificial polymers employed.
On a whole-animal method for the histochemical localization of enzymes under field conditions
Authors: Southward A. J. , Southward Eve C.
Published: May 2009

Various enzymes have been successfully localized in whole specimens of several groups of marine animals up to 5 mm body thickness. With certain exceptions the animals are fixed for a short time and then incubated in media modified from those designed for sections. After incubation the specimens are stored in fixative or buffer for later serial sectioning back at the laboratory.
Seasonal variations in the effect of temperature on the respiration of certain intertidal algae
Authors: Newell R. C. , Pye V. I.
Published: May 2009

The intertidal algae Enteromorpha, Ulva, Fucus, Porphyra, Chondrus and Griffithsia are subjected to wide semi-diurnal fluctuations in temperature during the summer months. Measurements of the rate of respiration of such algae in the dark at a wide variety of temperatures have shown that during the summer the curve relating respiration to temperature (R. T curve) has a relatively shallow slope of Q10 < 1·2 between 10° and 20 °C. Algae collected during the autumn and winter show R. T curves which have a shallow slope in regions approximating to the temperature of the shore at the time of collection. Thus the respiration of such intertidal algae is relatively unaffected by temperature fluctuation within the normal environmental range. Further, the form of the R. T curve is not a fixed phenomenon which is characteristic of a particular species of alga, but appears to be modifiable in such a way that the shallow region of the R. T curve is appropriate to the temperatures prevailing in the habitat. In this way the effects of temperature fluctuation upon respiration are minimized.
In situstudies on the cytochemistry and ultrastructure of a symbiotic marine dinoflagellate
Authors: Taylor D. L.
Published: May 2009

The intertidal actinianAnemonia sulcatais known to harbour yellow-brown algal symbionts which are similar in appearance to the zooxanthellae of hermatypic, or reef-building, corals and a number of other invertebrate species. The cytochemistry and structural morphology of the zooxanthella has been studied by light and electron microscopy, to help define it taxonomically and to reveal something about its relations with the actinian. These investigations confirm that it is a dinoflagellate and have revealed several structural adaptations which are formed as a result of the peculiar mode of life adopted by this alga. Of significance is the fine structure of the periplast, which may have a considerable bearing upon the type of relationship which can exist between the host and its symbiont. These findings are discussed in terms of other known instances of algal-invertebrate symbiosis.
The settlement behaviour of the larvae ofSabellaria alveolata(L.)
Authors: Wilson Douglas P.
Published: May 2009

Using larvae reared from artificial fertilizations in the laboratory, often for several months, many experiments have been made on factors promoting settlement ofSabellaria alveolata(L.). When at last able to metamorphose after many weeks of pelagic development, the larvae of this species crawl actively over any solid surfaces with which they happen to make contact, seeking indicative characters distinctive of their normal adult environment. If these are not found at once the larvae are able to postpone metamorphosis for weeks if necessary, remaining in a developmental state able both to swim and to crawl. If delayed too long in reaching a favourable environment some may metamorphose in the absence of normal environmental stimuli, others often become incapable of metamorphosing normally and do so abnormally, or they may die without metamorphosing.
The biology of Erythrops serrata and E. elegans [Crustacea, Mysidacea]
Authors: Mauchline J.
Published: May 2009

The general biology of Erythrops serrata (G. O. Sars) and E. elegans (G. O. Sars) is described. There are two main generations of E. serrata, a spring and a summer one, produced during the year although continuous breeding at lower intensities is present in the population between the most productive periods; females carry 14–18 young per brood in the spring and summer but these numbers decrease to 4–8 in winter broods. The marsupium of E. serrata is often lost after the brood emerges. The few data available for E. elegans suggest that its breeding behaviour is similar to that of E. serrata but fewer young per brood appear to be produced by this species. Both species feed on the surface layers of the bottom and the material in suspension, but E. serrata had, on occasion, remains of crustaceans among its stomach contents, indicating a carnivorous diet.
Experiments on the resynthesis of symbiosis in Convoluta roscoffensis with different flagellate cultures
Authors: Provasoli L. , Yamasu T. , Manton I.
Published: May 2009

The symbiotic condition of Convoluta roscoffensis has been resynthesized in vitro by feeding new-born colourless larvae with various clones of Platymonas convolutae Parke & Manton available in culture. Greening has also been brought about by feeding larvae with other species distinguishable from the natural symbiont by pyrenoid characters, but subsequent growth of the greened larvae was less and the length of time required for greening greater. The minimum presentation time effective in initiating greening with alien symbionts in 100% of tested larvae was also greater. Cell multiplication of successful symbionts is mitotic, division stages being demonstrated in sections of worms with different types of symbiont. When cultures of potential symbionts were made available competitively in pairs, greening normally involved only one member of a pair, success being apparently determined by the order of relative efficiency demonstrated in the single-culture infections. A chimaeral condition, with two different symbionts present together, was produced and is demonstrated—but only as a temporary phase in an experiment designed to give an alien symbiont a very long start before admitting the real one. In this experiment effective greening with Prasinocladus marinas did not impede prompt entry of Platymonas convolutae when it was supplied, and this was followed by rapid and complete elimination of the alien symbiont. An interpretation of these various findings is discussed in a preliminary way.
A volumetric respirometer for long-term studies of small aquatic animals
Authors: Livingston Robert J.
Published: May 2009

A modified volumetric respirometer was constructed for an extended series of precise determinations of the respiration of small aquatic animals. Food could be introduced and all operations could be carried out without disturbance to the animal. Provisions were made for the introduction of filtered, bacteria-free sea water between experimental runs. The advantages of the volumetric technique were combined with those of a running-water system to allow the continuous measurement of oxygen consumption under controlled conditions.
Day-night feeding by decapod crustaceans in a deep-water bottom community in the western Mediterranean
Authors: Cartes Joan E.
Published: May 2009

Changes in the composition of the diet, foregut fullness, and the degree of digestion of ingested food were taken into account in determining diel feeding activity of the numerically dominant species of decapod crustaceans dwelling on the Catalan Sea Slope (western Mediterranean). Two 24-h periods were sampled at two different stations on the upper middle slope (between 400 and 710 m) using bottom trawls. Additional foregut fullness data forAristeus antennatusandAcanthephyra eximiawere recorded below 1000 m. The influence of the relatively shallow-living mesopelagic fauna (Pasiphaeidae,Sergestes arcticus, euphausiids, and fishes) over the 24-h cycle apparently had a large effect on the feeding activity rhythms in the deep-sea decapods studied. Species can be classified into two different groups according to their feeding patterns. Thus, species whose diet was based on pelagic prey (Plesionika edwardsi, Plesionika martia, andA. eximia) exhibited a feeding pattern conditioned to the availability of this type of prey. In contrast, in those species in which pelagic prey contributed only a small portion of the diet (A. antennatus, Plesionika acanthonotus, Polycheles typhlops, andGeryon longipes) no variations in the foregut fullness or in the percentage of undigested prey in foreguts during the diel feeding cycles were recorded. The decrease in the influence of the abundance of mesopelagic fauna with depth, with a commonly accepted boundary at around 1000 m would be responsible for the progressive flattening out of activity rhythms among the species dwelling on the lower slope. Foregut fullness values for certain species with broad depth distributions in the Catalan Sea (A. antennatus, A. eximia), would support this hypothesis.
Feeding behaviour of the mussel,Mytilus edulis: responses to variations in quantity and organic content of the seston
Authors: Bayne B. L. , Iglesias J. I. P. , Hawkins A. J. S. , Navarro E. , Heral M. , Deslous-Paoli J. M.
Published: May 2009

Mussels were fed four concentrations of seston (between 0·99 and 10·3 mg total seston I−1), comprising three levels of organic content (71·9, 63·6 and 40·8%), made up from natural silt and two species of cultured phytoplankton. Two of the seston concentrations were below, and two above, the threshold at which pseudofaeces were produced. Measurements of physiological traits (filtration rates, pseudofaeces production, selection efficiency, absorption efficiency, absorption rates and rates of oxygen consumption) were made after 2 days and, for two of the seston concentrations, also after 12 days. When fed at a high concentration of seston of low organic content, the mussels increased their filtration rate, rejected a higher proportion of filtered material as pseudofaeces, and increased the efficiency with which filtered matter of higher organic content was selected for ingestion; this resulted in a constancy of the relationship between ingestion rate and the concentration of particulate organic matter, regardless of differences in seston organic content. Between 2 and 12 d, the mussels increased absorption rates for organics, primarily by increasing absorption efficiency, both for total organics and for the carbohydrate component of the diet. We suggest that these responses to changes in the food environment comprise physiological adjustments which result in higher net rates of absorption than would be predicted from considerations only of the organic/inorganic ratio of the suspended particles and assumptions of a non-compensating feeding behaviour.
The Organic carbon content of gravel bed herring spawning grounds and the impact of herring spawn deposition
Authors: Napier Ian R.
Published: May 2009

The dry weight and organic carbon content of eggs and components of Clyde spring herring eggs were measured at intervals during their development. Comparison with previously published data suggests that an increase has occurred in the weight of these eggs over the past thirty years. It is clear that only a small proportion of the material deposited in the form of herring spawn actually remains attached to the substratum when the larvae hatch and so is available for potential integration into the benthic food web. This was confirmed by the determination at intervals over two years of the organic carbon content of the gravel sediments on spawning grounds of the Clyde spring herring. Although the deposition of herring spawn resulted in an immediate marked increase in the carbon content of the spawning ground sediments, carbon levels quickly returned to pre-spawning levels and there was no evidence of any permanent or long lasting increase. This held true when the spawn died and decayed in situ and even when it was mixed into the sediment by wave action. The rapid decrease in carbon levels is attributed to the strong water movements which frequently occur over the spawning grounds.
Seasonal changes in diatom biomass, sediment stability and biogenic stabilization in the Severn Estuary
Authors: Underwood Graham J. C. , Paterson David M.
Published: May 2009

Epipelic diatoms represented the dominant microphy tobenthos on the intertidal mudflats of the Severn Estuary, south-western Britain. Algal biomass (measured as chlorophyllaconcentration) varied over a seasonal cycle and was strongly correlated with sediment shear strength and critical shear stress and therefore with position on the shore. High levels of diatom biomass were positively correlated with the concentration of colloidal carbohydrate within the surface sediments. The critical shear strength for incipient erosion was significantly correlated with position on the shore (moisture content) and with both chlorophyllaand colloidal carbohydrate, the latter being the best biochemical predictor for the incipient erosion threshold. The range of stress required to cause incipient erosion varied from 1.0 to 8.0 N m-2, with the sediment increasing in resistance landwards. Two-way analysis of variance using both moisture content and colloidal carbohydrate as variables explained the stability of the sediment better than individual pair-wise comparisons.
Consistency of Towing Speed and Sampling Depth for the Continuous Plankton Recorder
Authors: Hays G. C. , Warner A. J.
Published: May 2009

The mean annual towing speed of the Continuous Plankton Recorder (CPR) varied systematically between 1946 and 1991. By mounting a pressure transducer on the CPR to record towing depth, it was shown, however, that changes in towing speed did not cause a significant change in towing depth, although the mean towing depth (6–7 m, SD=l-7 m, N=77) was shallower than the previously assumed towing depth of 10 m. Thus the observed changes in towing speed are unlikely to have caused discontinuities in the CPR time-series by affecting sampling depth.

Long-term data sets play an important role in attempts to understand the causes of fluctua- tions in plankton abundance. The Continuous Plankton Recorder (CPR) survey provides multi- decadal information on plankton abundance in the North Sea and North Atlantic (McGowan, 1990), and is one of the longest standing marine plankton abundance time-series. However, while the CPR time-series has great potential, as with all other data sets spanning many years, questions may be asked regarding the consistency with which the data have been collected and hence the true continuity of the time-series.
Some Observations on Morphological Variation in the Red-Water Ciliate Mesodinium Rubrum
Authors: Crawford David W.
Published: May 2009

Living cells of the ciliate Mesodinium rubrum were observed and photographed during summer red-water events in the Southampton Water estuary, southern England. These blooms were characterized by increases in maximum cell diameter and range of cell size, a pronounced morphological variation of the ‘oral’ hemisphere, and the presence of free-swimming ‘fragments’ of larger cells.

Red-water occurrences caused by the planktonic, phototrophic ciliate Mesodinium rubrum (Lohmann) Hamburger & Buddenbrock, have been characterized by some of the highest recorded levels of chlorophyll and primary productivity for natural populations of marine phytoplankton (Lindholm, 1985; Taylor, 1982). However, as these events are rather unpredictable and all attempts to culture M. rubrum have failed, descriptions of the morphology of living cells have been rather limited. A study into the impact of red-tides caused by M. rubrum in the Southampton Water estuary presented a useful opportunity to observe morphological variation in living cells. Water samples were taken with a ‘Van-Dorn’ sampler, and transported in polyethylene bottles in a cool box. Living cells were observed and photographed at 400x magnification using the phase-contrast optics of an Olympus BH2 photomicroscope. Autofluorescence of living cells was examined using a Zeiss fluoresence microscope.
The Larva of The Oyster Ostrea Edulis During Starvation
Authors: Millar R. H. , Scott J. M.
Published: May 2009

Larvae of the oyster (Ostrea edulis L.), when released, can live for several days without food, and can grow to full size when subsequently fed. Energy is supplied by protein, carbohydrate and lipid of the larval body, all of which decrease during starvation. The measured decreases are sufficient to account for the energy expended as indicated by oxygen consumption.
Effects of Daylength on Growth and Reproduction of the Conchocelis-Phase of Porphyra Tenera
Authors: Dring M. J.
Published: May 2009

The conchocelis-phase of Porphyra tenera Kjellman has been grown in in vitro culture, and subjected to a variety of daylength treatments.

Details of the culture apparatus designed for these treatments are given, and quantitative techniques, which have been devised for estimating the growth and reproduction of the alga, are described and discussed.

Growth was found to be directly proportional to daylength within the range 8–16 h, but abundant sporangia were only formed in daylengths of 10 h or less. The interruption of a 16 h dark period by 1 h of light completely inhibited the production of sporangia, but exposure to 8 short-day cycles, followed by long days, induced the formation of as many sporangia as were found after 25 short days. These results are discussed with reference to the photoperiodic responses of flowering plants.