bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Relation of the Substratum to the Metamorphosis of Ophelia Larvae
Authors: Wilson Douglas P. 
Published: May 2009

Experiments with larvae of Ophelia bicornis Savigny have shown that they metamorphose most readily in sand from their natural habitat and with hesitancy or not at all in sands from other sources. Their natural sand consists largely of smooth rounded grains of quartz, very uniform in size; sands of
smaller and more angular grains are unfavourable to settlement and metamorphosis. It appears that size and shape of the sand grains, or perhaps, more likely, the sizes and shapes of the interstices among the grains, perceived probably by the tactile sense, is the main stimulus to metamorphosis. Chemical substances dissolving out of the sands do not seem to be responsible for this.There is a period of time, amounting under favourable conditions to several weeks, during which an Ophelia larva is able to settle and metamorphose as soon as it comes into contact with a substratum suitable for adult life.The ability of the larvae to distinguish bottom deposits suitable for adult life from those which are unsuitable must be of great advantage to the species in maintaining normal distribution and in conserving larvae.
The cycle of phosphorus in the waters of the English Channel
Authors: Armstrong F. A. J. , Harvey H. W. 
Published: May 2009

Determinations of total phosphorus in water samples have shown areas in the western English Channel with water containing as little as 10 mg. P/m.3, and other areas with double, and more than double, this concentration.The integral mean concentration of total P in the water column, 20 miles off-shore from Plymouth, has fluctuated between 10 and 16 mg. P/m.3 since June 1947.The changes which have taken place in this integral mean concentration are attributed to different water masses, of different total phosphorus concentration, passing through the area, rather than to a seasonal change in the total phosphorus content of a water mass. No marked deposition of phosphorus-containing detritus could be found.Changes in this integral mean were not coincident with changes in salinity. The geographical distribution of total phosphorus does not coincide with the geographical distribution of salinity.
Receptor organs in the coxal region ofPalinurus vulgaris
Authors: Alexandrowicz J. S. 
Published: May 2009

In the coxal region ofPalinurus vulgarisLatr. the following proprioceptors are present: (1) a thoracico-coxal muscular receptor, (2) two innervated elastic strands (depressor and levator receptors), and (3) a coxo-basipodite receptor. Thus,Palinurushas the same number of these organs as some Brachyura and Anomura, but differs fromHomarusandAstacus, which have five of them.In all the five thoracic segments carrying the legs the receptor organs inPalinurusoriginate on special receptor rods which are thin projections of the endophragmal skeleton.The muscle elements of the muscular receptor are surrounded by connective tissue which in the proximal part of the muscle forms a thick sheath. To the receptor rod the muscle is attached by a short tendon. The motor fibres reach the receptor muscle at about the midpoint of its course.
Gill structure in the common limpetPatella vulgata
Authors: Nuwayhid M. A. , Davies P. Spencer , Elder H. Y. 
Published: May 2009

The gills ofPatellaconsist of a row of triangular shaped leaflets suspended from the roof of the pallial groove. The surface of each gill is thrown into a series of transverse furrows. Tufts of cilia are irregularly distributed over the surface and generate a current of water which flows in the opposite direction to the flow of blood within. The central part of the gill comprises a large haemocoelic space traversed by trabeculae which contain muscle fibres and suggesting that the flow of blood through the gill may be under nervous control. A blood channel runs around the periphery of the gill.The epithelial layer bounding the blood space comprises a single layer of columnar epithelial cells. The outer surface is protected by a structured mucopolysaccharide glycocalyx held in place by a dense mat of microvilli. The cells contain clearly defined mitochondria, Golgi complex, lysosomes, rough and smooth endoplasmic reticulum. In addition, the non-ciliated cells are characterized by a layer of membrane-bound granules, of unknown function, in the apical cytoplasm.Phagocytes are frequently found associated with the basement membrane. They contain large membrane-bound granules and appear to move outwards between the epithelial cells to expel the granules at the outer surface of the gill. It is possible that the gill has an excretory as well as respiratory role in the physiology of the animal.
Development, location and relocation of sensory and neurosecretory sites in the eyestalks during the larval and postlarval life of Palaemon serratus (Pennant)
Authors: Bellon-Humbert Ch. , Thijssen M. J. P. , van Herp F. 
Published: May 2009

Ontogenesis of the eyestalk structures in Palaemon serratus has been studied during the larval and postlarval life by means of scanning electron microscopy (SEM) and light microscopy (LM). At hatching, a larval sensory pore is observed in the zoea. The organ of Bellonci is present with its typical onion bodies. During larval life, this organ grows and differentiates. Vacuolization in the organ of Bellonci starts in stage 4. At the same time, the giant neuron appears, but the sinus gland cannot be recognized before stage 5.During larval life, vesicular cells are present in the optic medullae with an increase during stages 4 and 5. The differentiation of the neurosecretory cells of MEX (medulla externa X-organ) and MTGX (medulla terminalis ganglionaris X-organ) occurs with metamorphosis. The main sensory pore appears with metamorphosis and becomes clearly visible in postlarval life.The movements of the structures, which occupy different positions in larvae and adults, are described in relation to the longitudinal axis of the eyestalk. A schematic representation explains the torsion of the eyestalk and the dynamics and growth during the formation of the eyestalk structures.
Monthly-mean residual flows through the Dover Strait, 1949–1972
Authors: Prandle D. 
Published: May 2009

An estimate is made of the mean value of residual flow through the Dover Strait for each month over the 24–year period from 1949 to 1972. The estimates are based on results from a modelling investigation by Prandle (1978) where it was shown that the residual flow consists of three components, (a) a tidal residual, (b), a wind-driven residual and (c) a flow due to a long-term gradient in mean sea level. The components (a) and (c) are assumed to be constant and the value of (b) is deduced using wind data recorded by Dutch Light Vessels located in the southern North Sea.The mean flow over the whole period amounts to 155 × 103 m3 s–1 into the North Sea with a maximum value of 364 x 103 m3 s–1 and a minimum of – 15 × 103 m3 s–1 (out of the North Sea). One notable feature of the complete time series is the surprisingly small variation in the annual mean flows; perhaps this stability in the annual flow is of significance to the marine biology of the area.The validity of the computed time series is established by reference to comparable data including a 9–year record, from cross-channel submarine cables, of the potential induced by the flow of water through the Earth's magnetic field. Additional comparisons are also made with the results of a previous study of daily-mean flows.
Comparisons of herring behaviour in the light and dark: changes in activity and responses to sound
Authors: Blaxter J. H. S. , Batty R. S. 
Published: May 2009

Comparisons of the behaviour of herring (Clupea harengusL.) were made in the light and dark by means of an infra-red sensitive TV system and video recording. Herring which were schooling in the light became less active in the dark, their swimming speed decreased, they tended to disperse and the proportion of gliding compared with swimming fish increased. Herring which were not schooling in the light increased their swimming speed in the dark.When subjected to transient sound stimuli herring made fast-startle responses. The proportion of fish responding was lower in the dark. The directionality of the response (the proportion turning away from the sound source) was the same in the light and dark suggesting there was no visual component in the response.The proportion of swimming and gliding fish affected both response rate and directionality. Gliding fish tended to have a higher response rate and better directionality than swimming fish, although this depended on the conditions of the experiment. The configuration of the body of swimming fish at the onset of a transient sound stimulus was important. Of the swimming fish, over 80% of the responders turned away from the direction in which the tip of the caudal fin was pointing at the onset of the stimulus. Gliding fish are in a better ‘neutral’ posture to initiate a startle response and to turn away from the sound source.Comparisons of awareness (sensory thresholds) in the light and dark using startle responses are complicated by differences in the numbers of gliding and swimming fish.
Light and nutrient status of algal cells
Authors: Droop M. R. , Mickelson M. J. , Scott J. M. , Turner M. F. 
Published: May 2009

Chemostats were used to construct nutrient (vitamin B12) and energy budgets for the flagellateMonochrysis(Pavlova lutheri(Droop) Green) under varying conditions of nutrient and light limitation and luxury, the aim being to describe light limitation and luxury in terms analogous to those of the Cell Quota nutrient model. Measurements were made of steady-state dilution rate, biomass, cell quota, cell chlorophylla, cell energy content, dark respiration and photosynthetic efficiency, under low irradiance (<13 W per m2).Cell energy content was 0·54 joules per million cells and was not influenced by growth rate or nutrient/light status. Cell chlorophyllawas 25% less in the nutrient-limited cultures and did not show a clear trend with growth rate except in cultures receiving less than 4·3 W per m2. The effective specific extinction coefficient was 0·12 cm2perμg chlorophyll. The photosynthesis/irradiance relation was linear. The mean slope (= efficiency) in samples from the light-limited chemostats was 0·225 and was independent of dilution rate. Samples from nutrient-limited chemostats showed a much lower slope, which decreased with decreasing dilution rate. These findings were confirmed by the chemostat kinetic data. Dark respiration varied with dilution rate in a hyperbolic manner and was greater in the nutrient- than the light-limited chemostat.Light level had no effect on the subsistence quota when the nutrient was limiting, whereas under light-limiting conditions the subsistence quotas were enlarged in inverse proportion to the incident irradiance, thus showing a threshold rather than multiplicative interaction between light and the nutrient.Energy absorption was very little reduced on nutrient limitation, the great reduction in overall efficiency being associated mainly with the reduction in photosynthetic efficiency.The reciprocal of photosynthetic efficiency was shown to be analogous to a standardized nutrient cell quota, and an analogous coefficient of luxury could be defined as the ratio of the light-limited to nutrient-limited photosynthetic efficiency at the same growth rate. Thus, light limitation and luxury could be described in terms compatible with the nutrient model without having to introduce new concepts, and a practical criterion between light- and nutrient-limitation could be provided.
Growth of the edible crab (Cancer pagurusL.) off south-west England
Authors: Bennett D. B. 
Published: May 2009

Moult increments, annual moult frequency and hence annual growth were determined from suture-tagged edible crabs (Cancer pagurusL.) released and recaptured off Devon, Cornwall, and Dorset.The average moult increments of males and females at a premoult carapace width of 100 mm were similar; at larger sizes the average moult increment of females was considerably less than that of males. Annual moult frequency ofC. pagurusin south-west England decreased with increase in size, females more so than males.As a result of the smaller moult increments and lower moult frequency of females, their annual growth is considerably less than that of males. This appears to be the result of three aspects of sex and reproduction: (1) reduction in moult increments, probably as a result of competition for nutritive resources between egg production and body growth; (2) the interruption of the moulting cycle by successive annual spawnings from a single impregnation at the previous moult; and (3) accentuation of the larger increments in weight at moulting of male crabs due to the allometric growth of their chelae. A consequence of the higher growth rate of males is the presence of very large male crabs – a distinctive feature of the population structure of the stock off south-west England.The growth of C.pagurusin south-west England was compared with published data for stocks off the east and north-east coast. Moult increments were similar for both areas, but there were considerable differences in the moult frequencies. In the south-west, males moult more frequently than females; the opposite is the case for the east and north-east crab stocks. A valid reason for this difference has not yet been established.
Notes on the Eggs and Larvæ of Some Plymouth Prosobranchs
Authors: Lebour Marie V. 
Published: May 2009

The following short descriptions of several of the eggs and larvæ of Plymouth prosobranchs, hitherto unknown or imperfectly known, are brought together, although many of them are not fully worked out. It is hoped in the near future to publish a general account of the British species with reference to all known forms, including those which have been specially described from Plymouth.Some of those described below have not yet been identified, but it is thought that it is worth while noting them for the benefit of future workers, especially some striking forms, important in the plankton on account of their size. This is notably the case with the three larvæ probably belonging to the Turridæ.
The Development of Audouinia tentaculata (Montagu)
Authors: Wilson Douglas P. 
Published: May 2009

(1) Adults of Audouinia tentaculata Montagu were induced to spawn in the laboratory; the eggs were fertilized and the larvæ reared to metamorphosis and early bottom stages for the first time.(2) The larvæ are yolky and do not feed. They have a broad prototroch and telotroch and a broad neurotroch. The ciliation of the head is rather complex. There are no bristles. When about ten days old they metamorphose.(3) During metamorphosis most of the cilia, except those of the neurotroch, disappear and their cells are absorbed internally.(4) Bristles appear for the first time a few days after metamorphosis. After a while branchiæ appear, followed by what are apparently tentacular filaments situated on segments anterior to those on which they occur in the adult.(5) Discussion centres on the position of the tentacular filaments and the first pair of branchial filaments in the young worm as compared with the adult. The segmentation of the anterior achaetigerous region also receives attention.
Irregular Development in the Larval History of Meganyctiphanes norvegica
Authors: Macdonald Roderick 
Published: May 2009

A new type of Nauplius belonging to Meganyctiphanes norvegica is described.Attention is drawn to irregularities in the development of the furcilia forms in which particular stages are sometimes omitted.It is suggested that in the larval history of M. norvegica in common with other Euphausids there is an indication of evolutionary progress in the group Euphausiaceæ.
The Biology ofLoligo ForbesiSteenstrup (Mollusca: Cephalopoda) in the Plymouth Area
Authors: Holme N. A. 
Published: May 2009

The distinguishing features of the common squid of British waters,Loligo forbesi, are summarized, and contrasted with those ofL. vulgaris.The life-cycle and growth ofL. forbesiare described, based on samples from trawl catches off Plymouth. This species seems to be an annual - young squid first appear in the trawl in late May, when their length is about 10 or 11 cm. Subsequent growth is rapid, and the males reach 30 cm and the females 25 cm by November. Spawning takes place mainly in December-January, but may continue into the spring. Neither sex survives beyond a single spawning season. Hatching of the spawn probably takes 30–40 days, and if the young squid taken in the trawl in late May hatched in the early part of the same year, a growth rate of about 25 mm/month would be required. Known growth rates for other species ofLoligoare about 20 mm/month, so that indicated forL. forbesidoes not seem to be impossibly high. The life-cycle is summarized in Fig. 8. There is also a summer spawning population, which grows to a rather smaller size at maturity, and which also seems to be annual.During the summerL. forbesiranges throughout the English Channel and southern North Sea, particularly in inshore areas. In October the squid migrate farther offshore and tend to occupy the western part of the Channel.Values for total weight of squid/2 h trawl are given, on a monthly basis, for 1966–9. The largest quantities are usually taken in October and November, the highest single figure being 30.54 kg/2 h trawl, in November 1967.
Depth Distribution of the carotenoid pigments and lipids of some oceanic animals. 2. Decapod Crustaceans
Authors: Herring P. J. 
Published: May 2009

SummaryAnalysis of the carotenoid pigments of decapod crustaceans has indicated that the visible differences in the appearance of species from different depth horizons are largely due to the disposition of pigments and not to differences in total amount of pigment relative to body size. Species from the upper mesopelagic zone have relatively few large chromatophores, and their chitin is either unpigmented or feebly pigmented. Species from deeper zones have very many small chromatophores and chitin heavily pigmented by unesterified astaxanthin. The major carotenoid pigments of almost all species are astaxanthin and its esters.Lipid analyses have shown that several species of Caridea have very high levels of lipid in the body, and that in many deep-water species wax esters comprise a large proportion of the total lipid. Specific patterns of distribution of the various lipid classes are found in different tissues, with wax esters particularly dominating the hepatopancreas lipids of deep-living species.The patterns of pigment and lipid distribution are discussed in relation to the depth distribution, light environment, and metabolic requirements of the different species.
The fatty acid composition of the leatherback turtleDermochelys coriaceaand its jellyfish prey
Authors: Holland D. L. , Davenport J. , East J. 
Published: May 2009

The leatherback turtle,Dermochelys coriacea(L.) studied was a male, weighing 916 kg, with a total dorsal length of 291 cm. It was beached on the Welsh coast, UK in September 1988 and is currently the largest leatherback ever recorded.Total lipid formed between 87.5 and 95.4% of the dry weight of representative samples of the blubber and 43.0% and 4.9% of the liver and pectoral muscle respectively. High levels of neutral lipid in the liver (79.0% of the total lipid) as well as the blubber (87.6–99.9% of the total lipid) suggest an important energy storage function for these tissues.Overall, with the notable exception of 22:lwll, fatty acids which are found in a putative jellyfish diet ofRhizostoma, Amelia, CyaneaandChrysaoraare also present in the leatherback liver and muscle, blubber and other fatty tissues. Fatty acid 22:lwll is present in the jellyfish samples, but is absent or at trace levels only in the leatherback tissues (0.1–0.3% of the total fatty acids).The polyunsaturated fatty acids of the w3 series 20:5w3, 22:5w3 and 22:6w3 are well represented in leatherback adipose tissues, muscle and liver as well as in the jellyfish examined. The leatherback and jellyfish lipids are therefore marine in character, but are also similar to terrestrial animal lipid in having a high proportion of fatty acids of the w6 series, principally arachidonic acid, 20:4w6. The significant levels of 20:4w6 in jellyfish total lipid (9.7–20.0% of the total fatty acids) and in the leatherback neutral lipid (1.0–10.9% of the total fatty acids) and phospholipid (0.6–15.5% of total fatty acids) fractions of all tissues sampled suggests that arachidonic acid assumes more importance in food chain relationships involving leatherbacks than in other marine food webs such as those involving fish.
On the breeding season of Lipophrys pholis (Pisces: Blenniidae) at Arrábida, Portugal
Authors: Almada Vitor C. , Barata Eduardo N. , Gonçalves Emanuel J. , De Oliveira Ruif 
Published: May 2009

Direct observations of egg masses on the shore indicates that Lipophrys pholis is a winter and spring spawner in Portuguese waters. The results are compared with those published for the British Isles.Lipophrys pholis, Linnaeus, 1758, is a very common intertidal fish in the north-eastern Atlantic and in the North Sea. Considerable work has been published concerning its breeding season in British waters (Lebour, 1927; Qasim, 1957; Shackley & King, 1977). The breeding season of the species at the southern limit of its range is almost unknown, and Zander (1986) mentions the period from April to August for the whole species. Based on dates of first appearance of larvae in plankton collected in the Bay of Biscay, Villegas (1981) concluded that breeding should have begun as early as the end of December.In this report we present data on the spawning season of this blenny based on direct observation of the presence of eggs and/or parental guarding males on the shore.Data were collected at a site located at Arrábida (38°28′N, 8°59′W), near Senibal, 50 km south of Lisbon, Portugal. In the course of behavioural observations on the breeding males of L. pholis, the area was visited at various intervals during the period 1986 to 1989. The nests were located intertidally in holes in vertical walls. On each visit, the presence of eggs and/or black males inside the nests was registered. Each nest was mapped for inspection in subsequent visits. The results are summarized in Figure 1.It is clear that in our study area breeding begins as early as December, and has virtually ended in June.
Rhizogeton Nudum (Cnidaria: Hydroida) in the British Isles
Authors: Jones D. 
Published: May 2009

Specimens of a hydroid species previously unrecorded in Britain have been found during the course of a long-term study of the coelenterate fauna of an intertidal mussel bed in Morecambe Bay, Lancashire. Specimens were sent for examination to Professor J. Bouillon who indentified them as Rhizogeton nudum Broch.The location and nature of the mussel bed, and the survey technique, have been described elsewhere (Jones & Miller, 1966; Jones & Clare, 1977; Jones, 1987). Rhizogeton nudum was observed in April and May 1987–91 and March 1989, on boulders where it was invariably associated with Clava multicomis (Forskal) and, more commonly, on mussel shells attached to these boulders. The few colonies recorded on boulders may have spread by stolon growth from attached shells.