bluuebunny/crossref_metadata_2025 huggingface dataset:
Planktonic ostracods from the Canary Island Region; their depth distributions, diurnal migrations, and community organization
Authors: Angel M. V.
Published: May 2009

The ostracods have been analysed from a day and night series of horizontal tows taken near the Island of Fuerteventura (Canaries). Thirty-five species were identified. Nineteen species were sampled in large enough numbers to describe their depthe distributions and the ranges of their vertical migrations. Seven species were too small to have been adequately sampled by the methods used, and the remaining nine species were too rare to draw any firm conclusions as to their depth ranges.
Is Phosphate Part of the Russell Cycle?
Authors: Joint Ian , Jordan Michael B. , Carr Martin R.
Published: May 2009

The evidence for variations in winter phosphate concentration as a component of the ‘Russell Cycle’ has been re-examined. The change from high phosphate concentrations prior to 1930 is the largest apparent variation in concentration through the period 1923–1987. However, these values are the result of a retrospective application in 1938, of a salt correction factor of 1–35. The justification for this factor is examined. It is concluded that there is sufficient uncertainty in the accuracy of the pre-1948 measurements of phosphate concentration to preclude their use in long time-series analysis. A statistical analysis of the post-1948 data shows that a simple first order autoregression model provides a perfectly adequate description of the data; the data can be considered as essentially random, with a small component of carry over from one year to the next. The evidence is weak that variations in winter concentrations of phosphate support the Russell Cycle hypothesis.
Retinal Anatomy of New Bresiliid Shrimp from the Lucky Strike and Broken Spur Hydrothermal Vent Fields on the Mid-Atlantic Ridge
Authors: Kuenzler R.O. , Kwasniewski J.T. , Jinks R.N. , Lakin R.C. , Battelle B.A. , Herzog E.D. , Kass L. , Renninger G.H. , Chamberlin S.C.
Published: May 2009

The 1989 discovery of a large dorsal eye on the hydrothermal vent shrimp,Rimicaris exoculata, debunked the prevailing opinion that all animals living around deep hydrothermal vents were blind. Recent dives with DSV ‘Alvin’ recovered new bresiliid shrimp [Chorocaris(Lucky Strike) andChorocaris(Broken Spur)] from two new vent fields on the Mid-Atlantic Ridge. The Lucky Strike species has recently been namedChorocaris fortunataand may be the same as the Broken Spur species - the retinal morphologies reported here are very similar. LikeR. exoculata, C. fortunatahas a visual apparatus adapted to the very dim light of its environment. Although in both species enlarged, non-imaging eyes appear to have evolved from the stalked compound eyes typical of caridean shrimp, those of C.fortunataare forward-facing whilst that ofR. exoculatais located dorsally. The massive array of photosensitive membrane (rhabdom) ofC. fortunatalies beneath a smooth cornea within a matt, white, reflecting matrix and occupies 80% of the available volume of the photoreceptors compared to the expected 10–15% of shallow water decapods. All screening pigment is located out of the light path at the bottom of the retina. There is no ultrastructural evidence for cyclic rhabdom shedding or renewal. Thus the cellular organization of C.fortunatais remarkably similar to that ofR. exoculataand distinct from its surface-dwelling relatives. This suggests that in these species imaging optics have been sacrificed to achieve the increased visual sensitivity necessary to detect the very dim light emitted from the throats of the black smoker chimneys around which they live
Seasonal Variation in Physiological Energetics of Mytilus Edulis and Cerastoderma Edule of Different Size Classes
Authors: Smaal A.C. , Vonck A.P.M.A. , Bakker M.
Published: May 2009

Seasonal variation of clearance, absorption and respiration rates of mussels Mytilus edulis (Mollusca: Bivalvia) and cockles Cerastoderma edule (Mollusca: Bivalvia) of various size classes have been measured under ambient temperature and sea-water conditions. Food availability was kept almost constant during the measurements.

Allometric body weight coefficients were bcl=0.5 for clearance and about br=0.7 for respiration rate of both species. Stepwise multiple regression suggested no relation for clearance rate of mussels with temperature and reproductive condition throughout the year. Respiration rates of mussels were highest during the reproductive period. Excretion rate was measured for mussels only and showed an allometric coefficient of bex=0.7 and an increase with temperature in spring. For cockles a significant relation of clearance rate, body weight and temperature was observed; at low temperature, clearance rates of small animals were more reduced than for larger animals. Respiration rates of cockles showed a significant relationship with temperature and reproductive condition.
Selective Tidal Stream Transport by American Eels During Homing Movements and Estuarine Migration
Authors: Parker Steven J. , McCleave James D.
Published: May 2009

Behaviour during homing movements and downstream migration of yellow- and silver-phase American eels (Anguilla rostrata) was observed using continuous ultrasonic telemetry in a tidal estuary. Homing subadult (yellow-phase) eels, non-displaced yellow-phase eels and adult (silver-phase) eels all used tidal currents as a transport mechanism (‘selective tidal stream transport’) and possibly as a means of orienting and moving in an appropriate direction. Yellow-phase eels displaced up the estuary and migrating silver-phase eels moved mostly at night and during ebbing tides. Yellow-phase eels displaced down the estuary moved mainly during flooding tides both day and night. Non-displaced eels used selective tidal stream transport to make long, round trip excursions and to move about their home range. Eels were at or near the surface during most of their movements, but were also vertically active, diving transiently to mid-water or to the bottom. During movements, the eels tended to drift with the current, or to swim slowly in the direction of the current. Although they used the tidal currents effectively as a transport mechanism, they were not precise in timing their movements to maximize transport on each tide. This study demonstrates that both yellow- and silver-phase eels use selective tidal stream transport during movements in tidal habitats and excludes some cues previously proposed to regulate the behaviour.
Relative Importance of Cleaning Behaviour in Centrolabrus Exoletus and other Wrasse at Arrábida, Portugal
Authors: Henriques Miguel , Almada Vitor C.
Published: May 2009

Underwater behavioural observations were conducted to evaluate the relative importance of cleaning behaviour in three species of common north-eastern Atlantic wrasse (Teleostei: Labridae). At the study site, the only cleaner was Centrolabrus exoletus. A total of 12 species was cleaned, with the wrasse, Symphodus melops and Labrus bergylta being the species most frequently cleaned. Neither S. melops nor Ctenolabrus rupestris, known to be cleaners in other sites or in captivity, could be observed cleaning other fishes. Centrolabrus exoletus was found to be a facultative cleaner fish with cleaning acts representing only 7% of the observed feeding acts. In focal observations of host fishes, the incidence of cleaning acts reached a level (11 h-1 per host) similar to that reported for tropical reef fishes and probably reflects the high numbers of cleaners available. Some factors that may affect the origin of the cleaning interactions are discussed.
The Contribution of Amphipoda to the Diet of Certain Inshore Fish Species in Kames Bay, Millport
Authors: Beare D.J. , Moore P.G.
Published: May 2009

Thirteen species of Amphipoda have been recorded from the stomachs of plaice and 11 species from dabs, with Perioculodes longimanus the most notable prey oedicerotid in both flatfish species sampled from the shallow sublittoral zone (<-6 m depth) at Kames Bay, Millport. Plaice took mostly bivalve siphon tips (Angulus sp.). Polychaetes were more numerous in larger plaice. Sand gobies specialized on small crustaceans, taking 13 amphipod species inter alia (with P. longimanus again the most notable oedicerotid). Amphipod numbers in sand goby stomachs increased with the length of the fish. Neither dabs nor sand gobies consumed bivalve siphon tips and only rarely consumed polychaetes. Although amphipods formed only a minor part of the diet of plaice, at the population density known for this species in this bay, its depredations would still constitute an important selective agency governing patterns of activity in epibenthic oedicerotids.
Fecundity and maturity of plaice (Pleuronectes platessa) from Cardigan Bay
Authors: Horwood J.W.
Published: May 2009

Measurements of fecundity are given for plaice (Pleuronedes platessa L.) sampled from Cardigan Bay. Values were compared with those obtained in 1953 from Cardigan Bay and from the eastern Irish Sea, and no differences were found; a marked contrast to results from the North Sea. Analysis of egg size showed that eggs develop earlier in older fish. A mechanism for ‘fine-tuning’ of fecundity is discussed. Size and age at maturity are calculated for Cardigan Bay plaice, and are compared with rates from surrounding areas. Plaice mature at an earlier age in Cardigan Bay.
Exotoxin production byGyrodiniumCf.aureolum(Dinophyceae)
Authors: Gentien P. , Arzul G.
Published: May 2009

Summer outbreaks ofGyrodinium aureolumin European coastal waters have been described since 1966 (Braarud & Heimdal, 1970). The coincidence of G.aureolumblooms and observations of noxious effects on fauna (Widdowset al., 1979; Tangen, 1977; Joneset al., 1982; Southgateet al., 1984; Potts & Edwards, 1987; Thain & Watts, 1987) is well documented. However, great differences in toxic effects have been found inin vitrostudies (Partensky & Sournia, 1986), with critical cell densities varying from 6×105cells 1−1to 3×107cells 1−1. Production of a lethal agent has been suggested by Turneret al.(1987). More recently, the toxic principle has been identified by Yasumotoet al.(1989).
The relationship of larval shell morphology to mode of development in marine prosobranch gastropods
Authors: Lima Gail M. , Lutz Richard A.
Published: May 2009

The larval shell of molluscs contains a preserved record of the organism's growth and developmental history. Many investigators have utilized the information recorded in the larval shell morphology to infer mode of development.

Marine prosobranch gastropods were collected from intertidal sites from Maine to Florida and were cultured in the laboratory. Scanning electron microscopy was used to document the relationship of larval shell morphology to development. Four species with planktotrophic larvae, Crepidula fornicata, Crepidula plana, Cerithium atratum and Ilyanassa obsoleta, and four species with non-planktotrophic development, Crepidula convexa, Littorina obtusata, Busycon canaliculatum and Urosalpinx cinerea, were successfully reared through metamorphosis.
Reproductive abnormalities in female Ocenebra erinacea (Gastropoda) resulting from tributyltin-induced imposex
Authors: Gibbs P.E. , Bryan G.W. , Pascoe P.L. , Burt G.R.
Published: May 2009

Imposex (the development of male sex organs on the female) has been studied in the European sting winkle, Ocenebra erinacea. In common with studies of other gonochoristic stenoglossan gastropods, the evidence gained from surveys of the south-west regions of England and Brittany (France) indicates that the phenomenon is a response to tributyltin (TBT) pollution. Close to sources of TBT, O. erinacea females exhibit structural abnormalities of the oviduct as a result of advanced imposex, including absence of a genital papilla and a normal vulva, a deformed bursa copulatrix and the presence of a longitudinal split. Copulation and capsule formation would appear to be inhibited in the worst-affected females. Such curtailment of breeding activity would result in population decline: direct evidence of the extinction of O. erinacea close to harbours, as is known for N. lapillus, is generally wanting for British shores, but the decline of the species in the Bay of Arcachon in France is attributable to TBT pollution.
The reproduction of Actinia equina L. var. mesembryanthemum
Authors: Carter M. A. , Thorp C. H.
Published: May 2009

Evidence is presented from a study of Actinia equina var. mesembryanthemum at Bembridge, Isle of Wight, which suggests that brooded young do not represent a random sample from a free-living larval pool. Parents in the laboratory will not accept juveniles placed on their oral disc. A. equina are, therefore, unlikely to be adoptive parents. Esterase heterozygote parents contain only heterozygote young. Sexual reproduction cannot account for this observation unless a parent selects its brood. As A. equina can distinguish self from non-self and juveniles may reproduce asexually, a fertilization - selection - cloning theory of reproduction is considered which could account for what is otherwise a conflicting body of evidence.
An investigation of some methods used for the determination of silicate in sea water
Authors: Liss P. S. , Spencer C. P.
Published: May 2009

Methods of filtration and storage of sea-water samples intended for silicate analysis have been investigated. The desirability in some circumstances of filtering water samples before analysis has been demonstrated. The behaviour of three recommended methods for the analysis of silicate in sea water has been compared by inter-calibration studies.
The buoyancy and locomotory movements of electric rays
Authors: Roberts B. L.
Published: May 2009

The mean weight in sea water of specimens of the electric ray, Torpedo nobiliana Bonaarte, was only 0·4 % of the weight in air compared with 4·4 % in other bottom-living rays. T. nobiliana was so buoyant because it had large livers (up to 20% by weight) containing a lot (up to 70 %) of oil of low density (0·91 g/cm3) and because some of the body tissues were less dense than in other rays.
Iron metabolism in Mytilus edulis II. Uptake and distribution of radioactive iron
Authors: Hobden D. J.
Published: May 2009

Mytilus edulis absorbs radioactive ‘ soluble’ iron from citrated sea water either directly or via adsorption on to the mucus used in feeding. The adsorption slows or ceases after 3—7 days when the total iron uptake is about I % of the total body content. In order of decreasing radioactivity, iron is absorbed into the byssus threads, renal organ, digestive gland, gut epithelia, gills, walls of heart and blood sinuses and gonadial and muscular tissues.
Age and growth of thick-lipped grey mullet Crenimugil labrosus in Irish waters
Authors: Kennedy M. , Fitzmaurice P.
Published: May 2009

The authors examined more than 900 thick-lipped grey mullet, Crenimugil labrosus (Risso), from 23 different localities on the Irish coast. The fish ranged in size from fry 1·5—2·0 cm long to adults of up to 58·5 cm long. The scales of mullet show annuli but, with growth, the innermost annuli on the scales become obscured.
Studies on Pogonophora II. Ultrastructure of the tentacular crown ofSiphonobrachia
Authors: Gupta Brij L. , Little Colin
Published: May 2009

The structure of the tentacular crown in a multitentaculate pogonophoran, Siphonobrachia ilyophora Nielsen, has been examined by light and electron microscopy. The fine structural organization of the tentacles is described and discussed in relation to the suggested functions for the tentacles in Pogonophora.
The dinoflagellate genus Ptychodiscus Stein
Authors: Boalch G. T.
Published: May 2009

The original descriptions of species of the genus Ptychodiscus are discussed. Recent material is examined both alive and preserved. It is concluded that the only valid species is Ptychodiscus noctiluca Stein. Ptychodiscus carinatus Kofoid, P. inflatus Pavillard and Diplocystis antarctica Cleve are all synonymous with this species.
Reproduction and feeding ofArgentina Sphyraena[Isospondyli] in the Clyde Sea Area
Authors: Halliday R. G.
Published: May 2009

Reproduction and feeding ofArgentina sphyraena L.were investigated during a study of the biology of this species in the Clyde Sea Area of Western Scotland from 1963 to 1966.
Distribution patterns and dispersal of prosobranch gastropods along a seamount chain in the Atlantic Ocean
Authors: Leal Josó H. , Bouchet Philippe
Published: May 2009

Based on qualitative data on prosobranch gastropods present at eight seamounts and islands of the Vitória-Trindade Seamount Chain off the eastern coast of Brazil, similarities at the species level are examined, and the effects of selection for different modes of development varying with increasing distance from the coast are investigated. Number of species decreases significantly from the continent towards easternmost localities. Similarity coefficients and cluster analysis suggest that similarities are greater among the western seamounts, followed by the eastern, most oceanic localities. Subtidal stations on Trindade Island show less similarity at specific level when compared with the remaining sublittoral stations. Percentages and absolute numbers of species with intracapsular metamorphosis decrease rapidly away from the coast in the sublittoral localities. However, there is little variation for the ratio planktotrophs/lecithotrophs among these localities, and their percentages remained constant over the entire Chain. In spite of the slightly wider range of distribution of planktotrophs within the Chain, the observations suggest that both planktotrophs and lecithotrophs can be effectively dispersed, probably by passive larval transport, in an ‘island-hopping’ pattern across the relatively small distances (100–250 km) that separate summits in the Chain. Notwithstanding shallow, subtidal conditions and intense isolation, percentages of planktotrophs and lecithotrophs also do not vary at the subtidal Trindade stations.
Virus-like particles in bacteria symbiotic in bivalve gills
Authors: Southward Eve C. , Southward A. J.
Published: May 2009

Thyasira gouldi,an arctic bivalve mollusc of the family Thyasiridae, has symbiotic, probably chemoautotrophic, bacteria living in its gills. In specimens collected from Loch Etive in Scotland in 1989, after the local population had undergone an unexplained decline, the gill bacteria contained numerous virus-like particles 60 nm in diameter. The bacteria are not lysed by the virus, and the particles are not present outside the bacteria except in phagocytic vacuoles of the gill cells where the bacteria have been digested, leaving the virus particles unchanged. Similar particles have been discovered in bacterial symbionts ofThyasira flexuosa,but in much smaller numbers.
Respiration and biometry in the sea cucumberHolothuria forskali
Authors: Astall C. M. , Jones M. B.
Published: May 2009

Relationships between wet body weight, dry body weight and ash-free dry body weight (AFDW) were established for the aspidochirote sea cucumberHolothuria forskali(Echinodermata: Holothuroidea); a wetdry weight ratio of 6–38:1 was found. Length-weight relations were also determined. Low oxygen tensions and mechanical trauma inducedH. forskalito eviscerate (70% of individuals tested). Respiratory measurements of intact and eviscerated sea cucumbers were determined at 17°C. For intact animals, oxygen consumption (ul h1) was directly related to AFDW (the slope of the regression line, b=0–60), whereas weight-specific oxygen consumption (Vo2; ul g1AFDW h) was inversely related to AFDW (b=0–54). Oxygen consumption of eviscerated sea cucumbers was independent of AFDW(b=0-\5), but Vo 2 was inversely related to AFDW (t–0–85). There were no significant differences between the respiratory rates of intact and eviscerated individuals, indicating thatH. forskaliis not so dependent upon respiratory trees for oxygen uptake as previously assumed.
The ultrastructure of the flagellar root system of Isochrysis galbana (Prymnesiophyta)
Authors: Hori T. , Green J. C.
Published: May 2009

The fine structure of the flagellar root system of Isochrysis galbana Parke (Prymnesiophyta) has been investigated and a reconstruction is presented. Associated with the left basal body and arising close to the base of the haptonema there is a root composed of a ribbon of approximately five microtubules running peripherally towards the ventral side of the cell. Near the basal body it is also associated with two additional bundles of microtubules which diverge from it and from each other passing deep into the cell.

On the right-hand side of the right basal body there is a root consisting of four microtubules (2+2) which runs peripherally in a dorsal direction. Another root, consisting of a single microtubule only, originates close to the distal connecting band between the basal bodies, and passes around the ventral side of the left basal body before following a course deep into the cell. In addition, several fibrous bands connect the bases of the flagella and haptonema. The general arrangement of the root system of 1. galbana is comparable with many other members of the Prymnesiophyta, but attention is drawn to a number of important differences, particularly between Isochrysis and some other members of the order Isochrysidales. The results are discussed in the context of the evolution, phylogeny and taxonomy of the Prymnesiophyta.

On the right-hand side of the right basal body there is a root consisting of four microtubules (2+2) which runs peripherally in a dorsal direction. Another root, consisting of a single microtubule only, originates close to the distal connecting band between the basal bodies, and passes around the ventral side of the left basal body before following a curse deep into the cell.
Tolerances to high temperature of infaunal bivalves and the effect of geographical distribution, position on the shore and season
Authors: Wilson James G. , Elkaim Bernard
Published: May 2009

There are four important influences on the temperature tolerance displayed by infaunal bivalves, namely their position on the shore, the depth to which they burrow, their geographical distribution and the seasonal cycle.

The temperature tolerance of a species is closely related to shore position and burrowing depth, since these both modify the actual range of temperatures to which the organism is exposed and the tidal variation in temperature. As one might expect, southern populations of a species tend to be lower on the shore than equivalents in northern Europe, but at any one location it is difficult to detect a difference in tolerance between individuals from the top of the shore and those from the bottom. Southern populations do have a higher tolerance to high temperatures than northern, despite the shift in littoral distribution. A similar pattern of response and shift in tolerance is shown between summer- and winter-acclimated specimens.

However, the seasonal shift in response to temperature is not entirely as might be expected, as oxygen consumption measurements show reverse acclimation (i.e. winter respiration rates lower than summer). Reverse acclimation has been demonstrated in a number of bivalve species, and the degree of reverse acclimation is here suggested to be related to the degree of deposit- or filter-feeding habit.

There is evidence that bivalves are capable of regulating to some extent their metabolic rate, independent of temperature. Six groups of Macoma balthica were investigated, of which the four from relatively high temperature environments regulated from 20°C, while the other two did not, suggesting that this capability can be acquired.
A Comparison of some methods for analysing changes in benthic community structure
Authors: Warwick R. M. , Clarke K. R.
Published: May 2009

Statistical methods for analysing changes in community structure fall under the three general headings of univariate, graphical/distributional and multivariate. These methods are applied to a variety of benthic community data (macrobenthos, meiobenthos, corals, demersal fish), from a variety of localities (intertidal/subtidal, temperate/tropical) and over both spatial and temporal scales. Four general conclusions emerge from this comparative study:

(1) The similarity between sites or times based on their univariate or graphical/distributional properties is usually different from their clustering in multivariate analyses.

(2) Species dependent (multivariate) methods are much more sensitive than species independent (univariate and graphical/distributional) methods in discriminating between sites or times.

(3) In examples where more than one component of the fauna has been studied, univariate and graphical/distributional methods may give different results for different components, whereas multivariate methods tend to give the same results.

(4) By matching multivariate ordinations from subsets of environmental data to an ordination of faunistic data, the key environmental variables responsible for community change may be identified.
Production of soma and gonad in maturing female Illex argentinus (Mollusca: Cephalopoda)
Authors: Hatfield E.M.C. , Rodhouse P.G. , Barber D.L.
Published: May 2009

Samples of female lllex argentinus were taken from the catch of a Japanese squid jigging vessel on the Patagonian Shelf during March 1986. Morphometrics of the somatic and reproductive organ systems and the histological structure of the mantle in relation to maturation were examined. The data suggest that growth and maturation occur simultaneously during most of the time that lllex argentinus females are on the feeding grounds. In a squid of a ‘standard’ mantle length the whole body mass increases relative to mantle length during maturation and growth of the reproductive organs. This is accompanied by a small but significant decrease in the relative mass of the mantle, head and viscera whilst the mass of the digestive gland remains constant. Although mantle mass of a ‘standard’ female squid decreases relative to mantle length with maturity this is not associated with degeneration of the mantle muscles. Energy and nutrient resources for maturation are apparently derived from the squid's food, not from reserves, and during the course of maturation there is an increasing shift of emphasis from somatic growth to production of gonad and accessory reproductive organs.
Larval and early post-larval development of the protobranch bivalveSolemya velum(Mollusca: Bivalvia)
Authors: Gustafson R.G. , Lutz R.A.
Published: May 2009

Early development in the north-west Atlantic awning clam,Solemya velum(Solemyoida: Solemyidae) was examined by light and scanning electron microscopy. Embryonic and pericalymma larval stages, typical of protobranch bivalves, developed within individual adhesive gelatinous egg capsules and offspring emerged at hatching as benthic crawl-away juveniles. Fertilized eggs were light orange in colour, spherical, and had a yolk-mass diameter of approximately 190 μm. Entirely ciliated cylindrical pericalymma larvae, with a length and width of 318 μm and 208 μn, respectively, were obtained within 24 h. These larvae lacked an apical ciliary tuft, possessed nine rows of calymma cells, and actively rotated within the egg capsule. During metamorphosis, which occurred within 48 h of fertilization, the transitory larval ectoderm was entirely ingested. The prodissoconch measured roughly 320 μm in length by 215 μm in height. The foot and ciliated gill buds were well developed by four days after fertilization and subsequent growth contributed to the dissoconch or adult shell. Hatching began at 13 d after fertilization when the shell measured approximately 402 μm in length by 251 μm in height. Actively crawling and burrowing juveniles were cultured for six months after fertilization and an ontogenetic sequence of encapsulated and juvenile shell morphology was obtained for identification purposes. Current contradictory hypotheses regarding the phylogeny of marine bivalve develop-mental types are reviewed in light of new information on the Order Solemyoida.
The effect of predation on the life histories ofLittorina obtusataandLittorina mariae
Authors: Williams Gray A.
Published: May 2009

Littorina obtusatais an epiphytic gastropod which lives for three to four years on its hostAscophyllum nodosum, a long-lived brown alga. Most of the population consists of adults, present throughout the year in the size range 14 to 17 mm. Newly hatched individuals appear between April and October with a peak in July; the immature winkles grow to merge with the adult cohort in May.

In contrastLittorina mariaeis an annual; newly hatched individuals grow to maturity by the winter of their first year. Those reaching maturity overwinter as adults but very few live beyond spring of their second year. The population dynamics ofL. mariaeare closely linked with changes in the biomass of the algaFucus serratuson which it lives.
Observations on the swimming and buoyancy ofCymbulia peroni(Gastropoda: Thecosomata) made from a submersible
Authors: Harbison G.R.
Published: May 2009

The swimming and buoyancy of the gelatinous pteropod,Cymbulia peroni, was observed and recorded on videotape from a submersible in the western Mediterranean. When not swimmingCymbulia peronihangs neutrally buoyant, with its parapodia outstretched and motionless. Two modes of swimming were observed, slow swimming and rapid or ‘escape’ swimming. Slow swimming predominated, at speeds between 2 and 11 cm s−1. Most slow swimming was directed vertically up or down. Slow swimming is probably used for vertical migration and the avoidance of turbulence. Turbulence frequently occurs both at epipelagic and mesopelagic depths in the Mediterranean. Escape swimming was more rapid, and speeds up to 40 cm s−1were measured. Differences between slow and escape swimming appear to be quantitative rather than qualitative, in contrast to other cymbuliids.Cymbulia peroniis an active and vigorous swimmer, clearly capable of vertical migration, and probably attains speeds greater than the highest measured in this study. Its behaviour in the field differs dramatically from its behaviour in the laboratory.
Pairing behaviour, reproduction and diet in the deep-sea holothurian genus Paroriza (Holothurioidea: Synallactidae)
Authors: Tyler P.A. , Young C.M. , Billett D.S.M. , Giles L.A.
Published: May 2009

Deep-sea holothurians of the genus Paroriza (Family Synallactidae) have often been observed or photographed in pairs or triplets. Observations of tracks on the sea floor suggest that pairs may remain together for some time. We explored the reasons for pairing in a study of reproductive condition and diet, using animals collected by trawl from the bathyal and abyssal north-east Atlantic and by manned submersible from the bathyal slope of the Bahamas. Both species of Paroriza studied were found to be simultaneous hermaphrodites producing yolky oocytes. Oocytes of Paroriza pollens were about 350μm in diameter, whereas those of P. prouhoi were up to 450μm. Examination of oocyte size-frequency distributions suggests that reproduction is continuous for both species. Neither mean oocyte size, nor shape of the oocyte size-frequency distribution differed significantly between paired and unpaired P. pallens collected during the same season. These deposit-feeding holothurians appear to take food from the nutrient-rich phytodetrital layers on the surface of the sediment. Because their food resources are probably not patchy on small scales, the observed pairs are not likely to be feeding aggregations. We hypothesize that pairing increases the likelihood of external fertilization and that spawning in these species may be induced at any time by the presence of a conspecific rather than by seasonal cues.
Patterns of variation in Aat-1 allele frequencies in rough periwinkles (Littorina) suggest similar selection regimes rather than conspecificity
Authors: Grahame J. , Mill P.J. , Double M. , Hull S.L.
Published: May 2009

It has been argued by Johannesson & Johannesson (1990b) that the pattern of common genetic variation in Littorina saxatilis (Olivi) and Littorina neglecta Bean indicates gene flow in sympatric populations of these ‘species’. They suggest that L. neglecta is not a good species. We report that a gene diversity analysis of polymorphism in Aat-1 suggests that L. saxatilis and Littorina arcana Hannaford Ellis also show common features in allele frequency distribution. This casts doubt on the argument of Johannesson & Johannesson (1990b) from enzyme polymorphism data on Aat-1 that L. neglecta may simply be an ecotype of L. saxatilis. It seems likely that the similarities are due to operation of the same selection factors on all these species.
The organization of skeletal tissues in the spines ofEchinus esculentus
Authors: Pilkington J. B.
Published: May 2009

The relationship between the calcite skeleton and associated cells in the spines of Echinus esculentus is described. The cell bodies lie in channels within the skeleton and cytoplasmic processes extend from them toward the calcite. Swollen regions of the cytoplasmic processes contain organelles such as mitochondria and various vesicles. The plasma membranes of the cytoplasmic processes appear to spread over the calcite surface which is thus topologically intracellular. A considerable portion of the stereom space is extracellular and contains an extracellular fluid and collagen fibres.
On the European species ofEubranchus[Mollusca Opisthobranchia]
Authors: Edmunds Malcolm , Kress Annetrudi
Published: May 2009

On the basis of extensive material from Plymouth an attempt has been made to determine the specific limits of the European species of the eolid genusEubranchusForbes. From a study of the living animals, jaws, radulae and reproductive systems, it is concluded that five species can be recognized as occurring commonly in Britain,Eubranchus tricolorForbes (=Galvina viridulaBergh),E. farrani(Alder & Hancock),E. pallidus(Alder & Hancock),E. cingulatus(Alder & Hancock) andE. exiguus(Alder & Hancock). These species are all variable in coloration, but they can nevertheless be easily distinguished by coloration as well as by morphological and ecological characteristics. A further species,E. doriae(Trinchese) from the Mediterranean, was also examined and appears to be distinct. No material ofEubranchus rupiurn(Moller) andE. vittatus(Alder & Hancock) was available for examination, but these are provisionally maintained as distinct species. The European speciesof Eubranchusare compared with species from other parts of the world in an attempt to decide how many genera should be recognized. It is concluded that the armature of the penis and the liver branching do not form good generic characters, and that consequentlyCapelliniais to be regarded as a junior synonym ofEubranchus.
Influence of oestradiol 3-benzoate upon the plasma content of calcium and vitamin A aldehydes in the Cod, Gadus morhua
Authors: Woodhead P. M. J.
Published: May 2009

Studies made on the cod of the Barents Sea showed that in the adult female fish there were regular seasonal variations in the level of calcium and vitamin A aldehydes in the blood (Plack & Woodhead, 1966: Woodhead, 1968). These changes were directly related to each other (Woodhead & Plack, 1968) and it was suggested that the changes of both blood constituents might be influenced by oestrogen secretions from the ripening ovary. It has now been confirmed that oestradiol treatment increases the level of vitamin A1 aldehyde in immature cod (Plack & Pritchard, 1968), and the present paper describes the effect of oestrogen treatment on the concentration of calcium in the plasma, also relating this to vitamin A aldehyde changes.
Growth form and environment inSaccorhiza polyschides
Authors: Norton Trevor A.
Published: May 2009

Descriptive work carried out in two localities at Port Erin, Isle of Man and three localities at Lough Ine, County Cork has shown that there were marked morpho-logical and anatomical differences between sporophytes ofSaccorhiza polyschides(Lightf.) Batt. living in different habitats. The plants developed broad, flimsy, curved, non-digitate blades in areas of weak current; long, tough, flat, very digitate blades in strong current and short, tough, flat blades with few digits in habitats without current, but subject to wave action. By means of culture techniques in the laboratory and transplant experiments in the sea the variations were shown to be phenotypically based. The transferred plants adopted the morphology of the population into which they were moved.
A Glossary of the Extant Haptophyta of the World
Authors: Jordan R.W. , Kleijne A. , Heimdal B.R. , Green J.C.
Published: May 2009

The Haptophyta comprises a group of microalgae of particular importance in marine habitats, often occurring in ‘bloom’ concentrations, sometimes with devastating effects where the bloom is composed of species toxic to other forms of life. The most familiar species are the coccolithophorids, unicellular organisms encased in calcified scale-like structures, the coccoliths, which are readily preserved in marine sediments and have for a long time been important indicators in micropalaeontological studies. In the middle of this century it was recognized that there was a need to compile and standardize the terminology used in coccolith morphology (Braarud et al., 1955; Halldal & Markali, 1955). This approach was continued by several authors (e.g. Hay et al., 1966; Okada & McIntyre, 1977; Tappan, 1980; Perch-Nielsen, 1985) in published articles, and in the report from a Round Table session at the Rome 1970 Plankton Conference (Farinacci, 1971), which included terms from both fossil and extant taxa. Over the last two decades many new terms have been introduced as observations on coccolith morphology have improved through the use of the electron microscope, and recent glossaries covering various aspects of haptophyte terminology have been published by Heimdal (1993), Kleijne (1993) and Margulis et al. (1993).
Nano- and Microplankton Dynamics during the Spring Phaeocystis Sp. Bloom in McMurdo Sound, Antarctica
Authors: Stoecker Diane K. , Putt Mary , Moisan Tiffany
Published: May 2009

The seasonal development of the microbial food web in eastern McMurdo Sound, Antarctica, was investigated during and immediately after the 1990–1991 bloom of Phaeocystis sp. (Prymnesiophyceae: Prymnesiales). From 23 November to 7 December, which was before the appearance of macroscopic colonies of Phaeocystis, both phytoplankton and Protozoa were low in abundance. During the Phaeocystis bloom (~10 December to 7 January), phytoplankton biomass was high and was dominated by colonial and singlecelled Phaeocystis, but other phytoplankton taxa, including diatoms and photosynthetic dinoflagellates, co-occurred. Heterotrophic nanoplankton and protozoan microzooplankton increased dramatically in biomass during the bloom. Non-thecate heterotrophic dinoflagellates were the most abundant microzooplankters. There was no evidence for inhibition of the microbial food web by Phaeocystis. By the post-bloom period, macroscopic colonies were rare and phytoplankton biomass had declined markedly. Microzooplankton biomass continued to rise until the end of the sampling period (23 January). Microfaecal pellets (median size range, 10–30 μm) were abundant during the bloom and post-bloom periods. In the post-bloom period, the heterotrophic protistan assemblage became very diverse, with numerous trophic linkages within the microbial food web. The abundance and diversity of the heterotrophic protist assemblage suggests that there was little control of protists by metazoans and that the microbial food web, consisting of bacteria, algae and Protozoa, was poorly coupled to metazoan zooplankton.
Population Dynamics of the Polychaete Nephtys Caeca in an Intertidal Estuarine Environment (Quebec, Canada)
Authors: Caron Alain , Boucher Louis , Desrosiers Gaston , Retiere Christian
Published: May 2009

An extensive study of an intertidal population of Nephtys caeca Fabricius (Annelida: Polychaeta) was conducted from 1986 to 1988 in I'Anse-à-l'Orignal on the southern shore of the lower St Lawrence Estuary. The sampling, carried out at three levels in the intertidal zone, was designed to study spatio-temporal variations in oocyte diameter (1988), age (1986), density (1986–1987) and individual body weight (1986–1987). The highest oocyte diameters were found in early May when breeding occurred. A relatively long period (from 20 June to 23 August), when oocytes were not visible with a binocular microscope, was also observed. Oocyte maturation began in late summer / early autumn. Settlement did not seem to take place in the intertidal zone, suggesting sublittoral larval recruitment. Peak densities occurred at the intermediate tidal level only in June. Nephtys caeca density varied significantly according to tidal levels, but only in 1987. The number of larger individuals (>320 mg in partial weight) increased markedly with decreasing level on the shore. At the lower tidal level a significant temporal variation in body weight was observed, while mean weight reached its maximum value in July or August 1986. Body weight later decreased progressively (July-November). In June and July 1986 arrivals of juveniles were seen to be greater at every level than during 1987. Six growth-rings were found in the pharyngeal jaws of the individuals in this intertidal population (November 1986). The decomposition of the polymodal weight-frequency distributions of individuals >75 or >85 mg in partial weight isolated four or five size-groups (MacDonald & Pitcher, 1979).
Growth, Trematode Parasitism, and Longevity of a Long-Lived Marine Gastropod (Ilyanassa Obsoleta)
Authors: Curtis Lawrence A.
Published: May 2009

Ilyanassa obsoleta (Say) (Mollusca: Neogastropoda) is a conspicuous biotic element of marine / estuarine habitats along the eastern North American coast. Growth among larger individuals (-18–30 mm shell height) has not been assessed. Trematode infections are common in this group and their effect on growth must be considered. Snails were individually marked, measured, and released on the Cape Henlopen sand-flat at the mouth of Delaware Bay. Shell height change (growth) and trematode parasitism were assessed in recaptured snails. Most or all growth occurred in June and July. Mean growth of uninfected snails was 1–2 mm per season. Snails that started out larger grew more slowly, but there was much individual variability. Mean growth of parasitized snails was 0–2 mm per season and independent of initial size. The maximum age of this snail is currently documented at 7 y, which is too low. Size reflects age only approximately. However, the minimum and maximum age of a snail of given size, based on maximal and minimal growth per season, can be estimated. A mid-range estimate for lifespan of unparasitized and parasitized individuals is 30–40 y.
Commensalism of a Bivalve, Peregrinamor Ohshimai, With a Thalassinidean Burrowing Shrimp, Upogebia Major
Authors: Kato Makoto , Itani Gyo
Published: May 2009

Ecological, behavioural and anatomical observations of a commensal bivalve, Peregrinamor ohshimai (Mollusca: Galeommatoidea), were carried out in a tidal mudflat in the Seto Inland Sea, Japan. The bivalve attached specifically to the longitudinal groove of the ventral side of the cephalothorax of thalassinidean burrowing shrimps, Upogebia major and Lf. narutensis (Crustacea: Decapoda), singly, dorso-ventrally and longitudinally, using its byssus, with its anterior part towards the head of the host. The mantle of the commensal bivalve has wide anterior (branchio-pedal) and narrow posterior (exhalant) apertures. In the living organism, the extended anterior edges of the mantle protrude from the shell and are inserted into the host's filtering basket, which is formed by the setal rows of the first two pairs of pereiopods and utilized for intercepting suspended matter. By beating its pleopods in a U-shaped burrow, the filter-feeding Upogebia shrimp creates water currents, which are also utilized by the commensal bivalve for filter-feeding. The shell length of the commensal bivalve was in proportion to the host's carapace length. This suggests that the veliger larva attaches to a young host and grows, thus maintaining the host-commensal morphological matching. The bivalve is a hermaphrodite and individuals of >8–5 mm in shell length were already producing eggs. Anatomical observations suggest that P. ohshimai is most closely related to the Montacutidae in Galeommatoidea.
An Acoustic Bottom Classification Survey of Strangford Lough, Northern Ireland
Authors: Magorrian B.H. , Service M. , Clarke W.
Published: May 2009

As part of an investigation into the impact of commercial trawling on the benthos of Strangford Lough a map of the distribution of the benthic communities in the Lough was required. To provide this an acoustic bottom classification survey of the Lough was carried out using a commercially available system, RoxAnn. RoxAnn processes the information from a conventional echo-sounder to determine the nature of different substrata. Underwater cameras were used to obtain ground truth data to compare with the RoxAnn data. Used in conjunction, the two surveys provided valuable information on the different bottom substrata and associated epibenthic communities present in the Lough.
Geotaxis and Phototaxis inElphidium Crispum(Protozoa: Foraminiferida)
Authors: Manley C.J. , Shaw S.R.
Published: May 2009

Laboratory experiments were carried out uponElphidium crispumto determine the mechanism by which this species remains epifaunal, by investigating geotaxism, phototaxism, temporal influence and responses through ontogeny. Different size-classes of specimens were tested for phototaxism and geotaxism, over four and five months respectively. Specimens of the smallest size-class tested (250–355 μm) were significantly phototaxic and geotaxic. Significant positive phototaxism was demonstrated in all tests except one, with specimens in the size-class 500–1000 μm giving particularly significant results for the months of June and July 1994. Specimens were significantly geotactic for three of thirteen tests: both negative and positive geotaxism were demonstrated.
The Crystallography and Possible Origin of Barium Sulphate in Deep Sea Rhizopod Protists (Xenophyophorea)
Authors: Hopwood J.D. , Mann S. , Gooday A.J.
Published: May 2009

Xenophyophores are a group of giant deep sea protists characterized by intracellular barium sulphate (BaSO4) crystals. X-ray diffraction, electron diffraction and electron microscopy studies have been performed on barium sulphate crystals from three xenophyophore species (Aschemonella ramuliformis, Reticulammina labyrinthica, Galatheammina lamina) obtained at bathyal and abyssal depths in the north-eastern Atlantic. Two populations of crystals were observed. The first were tablets, ~2μm in length and rhombic or hexagonal in outline. In both cases, the tabular face was of index (100). The second population consisted of much smaller particles (<0·5 μm) of poor crystallinity. A comparison of the larger xenophyophore crystals with synthetically grown crystals indicated that the former probably grew at low supersaturation (S<25) in solutions of low to moderate ionic strength (I<l·0 M). Some preliminary observations of the cellular organisation ofA. ramuliformisare reported. The protoplasm is multinucleate and characterized by what seems to be a system of extracellular lacunae formed by imaginations of the cell wall. Similar features have been observed in the deep sea foraminiferanRhizammina algaeformis. Possible origins of the BaSO4crystals and the taxonomic relationship between xenophyophores and certain foraminiferans are discussed.