bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reproductive biology of the serpulid Ficopomatus (Mercierella) enigmaticus in the Thames Estuary, S.E. England
Authors: Dixon D. R. 
Published: May 2009

Details of the gross cellular changes taking place in the gonadial tissues and coelom of Ficopomatus during the annual reproductive cycle are presented. There is no true gonad in either sex; instead, germ cell precursors are produced by divisions of a germinal epithelium associated with the ring blood vessels in the intersegmental septa.Segments producing gametes do not all develop simultaneously; the posterior segments are generally at a more advanced stage of sexual maturity. The later stages in gamete development take place free in the coelom, where nourishment is supplied presumably by the mobilization of materials formerly stored in tissues surrounding the gut.Spawning commences in June and continues through to October, with peak activity coinciding with the period of high water temperature in August and early September. The adult population comprises males, females, and protandrous hermaphrodites which in the male phase become sexually mature in advance of the rest of the population, and as females later on. These transitional individuals are thought to contribute a negligible amount to the effective reproductive output in those populations living where there is marked temporal constraint on the period of reproduction.The different reproductive capacities of temperate and tropical Ficopomatus are considered.
A Large-Volume Pump System for Studies of the Vertical Distribution of Fish Larvae Under Open Sea Conditions
Authors: Harris R. P. , Fortier L. , Young R. K. 
Published: May 2009

A large-volume pump system (2.8 m3 min-1) for sampling fish larvae under open-sea conditions is described. Comparative efficiency trials by day and night showed that the pump was generally as efficient, or in some cases more efficient, in capturing larvae than vertically hauled 200 μm WP2 nets, though there was some evidence of visual avoidance by particular larval size classes during daylight. The pump system is particularly appropriate for investigating fine-scale vertical aggregations (1–10 m3) of larval fish in relation to the distribution of their food organisms.INTRODUCTIONStudies of the distribution of larval fish and their food organisms in relation to physical structure in the water column require sampling techniques capable of resolving fine-scale temporal and spatial distributions. As an alternative to conventional nets, large-volume pumps, sampling at rates in excess of 1 m3 min-1; provide such a capability. Major benefits of using large pumps in addition to temporal and spatial resolution are that a wide range of sizes of plankton including larval fish can be sampled simultaneously in relation to physical and chemical properties of the water column; there is reliable control of the volume of sample filtered and problems of clogging of towed nets are avoided; long series of sequential samples can be taken in studies of small-scale distribution; and instrumentation with in situ CTD and fluorometers at the intake enables real-time control of sampling in relation to physical structure.General engineering considerations for using such pumps have been reviewed in detail by Miller & Judkins (1981), and a particular area of application has been in power-plant entrainment studies in shallow fresh water (Portner & Rhode, 1977; Bowles & Merriner, 1978; Gale & Mohr, 1978; Ney & Schumacher, 1978; Elder et al. 1979; Leithiser, Ehrlich & Thum, 1979; Cada & Loar, 1982).
New Records of Tubeworms Established in British Harbours
Authors: Thorp C. H. , Jones-Knight Phyllis , Jones-Knight E. W. 
Published: May 2009

Populations of the spirorbid Pileolaria berkeleyana ( = P. rosepigmentata) are recorded in harbours at Plymouth, Falmouth and Portsmouth and of three similarly abundant serpulids, Filogranula calyculata and Metavermilia multicristata at Abereiddy and Vermiliopsis striaticeps at Falmouth. Ship-borne introductions may well have occurred but the Abereiddy serpulids have more probably come from undiscovered populations nearby, in areas too rocky and deep for easy sampling.INTRODUCTIONThree apparently exotic species of tubeworms, a spirorbid and two serpulids, have been established for at least five years in aquarium tanks at the Portsmouth Polytechnic Marine Laboratory. The tanks receive a continuous flow of unfiltered sea water, which is pumped from Langstone Harbour via a header tank, with little if any change in temperature. They contain many slate slabs from a flooded quarry (at Abereiddy, in South Wales), which had been opened to the sea in 1932 and is used as a harbour for small boats. The most recent transfer of slates to Portsmouth was in 1972. The slates were brought in because they bore populations of a native spirorbid (Thorp, 1975), but the associated fauna was not closely studied at that time because a general account of Abereiddy quarry and its fauna was being prepared by Hiscock & Hoare (1975).The exotic serpulids occurred particularly on the undersides of the slates, but had not been noted by Hiscock & Hoare, nor in any other British fauna list. They also occurred on the underside of a disused heater/cooler plate supporting the slates in one of the tanks, which indicated that they had been breeding in that tank.
The Ecology of Idotea Species (Isopoda) and Gammarus Locusta (Amphipoda) on Surface Driftweed in Galway Bay (West of Ireland)
Authors: Tullyand O. , Céidigh P. Ó 
Published: May 2009

Four species of Idotea and Gammarus locusta were associated with drifting seaweed. In all species and throughout the year juveniles predominated. Peak numbers occurred in summer when most seaweed was collected, but /. emarginata and /. baltica were common also in spring and autumn. All species also occurred freely swimming at the surface. No diel vertical migration was detected.Drifting alga provides only a temporary and unstable habitat for associated species but is important as a medium for habitat expansion and as a refuge from predators for actively dispersing juveniles.Breeding activity in all species peaked during the summer but continued at a low level for most of the year.
The origin and recruitment of bass, Dicentrarchus labrax, larvae to nursery areas
Authors: Jennings S. , Pawson M. G. 
Published: May 2009

The distribution of bass, Dicentrarchus labrax (L.), eggs taken in ichthyoplankton surveys of the Bristol channel and eastern Celtic Sea from April 1989 to May 1990 indicates that bass spawned predominantly offshore during March and April. Seventy-two bass larvae were captured by ring net and 16 by high-speed tow net during 19–27 May 1989, and 11 were captured by ring net during April and May 1990. Larvae were most abundant inshore where the water column was unstratified and less than 50 m deep.Back-calculated egg fertilization dates were determined for 58 larvae captured in May 1989 by ring net, using estimates of temperature-dependent egg and larval development rates and counts of daily growth increments on sagittal otoliths. These dates ranged from 5 April to 10 May 1989, later than those for most young-of-the-year bass which first appeared in Welsh estuaries during June 1989. This implies that bass larvae would have been more abundant before the May sampling period, even though these catches are the largest reported from UK waters.Bass larvae of 5–11 mm live notochord length were captured close to estuarine nursery areas, and their mean growth rate was approximately 0·2 mm per day. However, the smallest bass first arriving in the nursery areas during June, July and August were always larger than these larvae, and predominantly 15–20 mm total length. It is suggested that bass larvae hatching offshore either perish or are transported to unstratified coastal waters where they feed and remain for at least 30 days prior to their recruitment to the nurseries.
Marine Pelagic Ciliates and Their Productivity During Summer in Plymouth Coastal Waters
Authors: Pilling E. D. , Leakey R. J. G. , Burkill P. H. 
Published: May 2009

The ciliate list for Plymouth waters has been extended by 14 species using modern taxonomic techniques. Ciliates were abundant in the plankton where they formed a significant food resource. Their community biomass and production was estimated to average 12 µ C 1 and 9 µ C 1 respectively during the summer. The ciliate community was dominated by a diverse assemblage of aloricate choreotrichs, suggesting a complex trophic role for this protozoan group.Ciliate protozoans are ubiquitous and often abundant in marine waters where they are frequently considered to play an important ecological role in trophic flux and nutrient cycling within the plankton (Fenchel, 1987). In spite of this, however, their ecological role in British coastal waters is poorly understood. In Plymouth waters, for instance, there has been only one previous study of marine pelagic Protozoa (Lackey & Lackey, 1963), despite the presence of a marine laboratory in the region for over 100 years. As the study by Lackey & Lackey (1963) focused solely upon the taxonomy of local protists, the ecological role of protozoans in Plymouth waters is unknown. To redress this anomaly the present pilot study was undertaken in Plymouth waters with the following objectives: to identify the dominant ciliates from this region using techniques unavailable to Lackey & Lackey (1963), to quantify ciliate abundance and cell sizes, and to estimate their biomass and production.Triplicate water samples were collected, using a 3-litre water bottle, from surface waters at each of four stations along a 20-km transect between Plymouth Sound (50°21'N 04°09'W) and the Eddystone Rock (50°ll'N 04°16'W) during June, July and August 1988.
Patterns of variation in the dry body weight of Calanus finmarchicus in copepodite Stage V during autumn and winter in the Firth of Clyde
Authors: Grigg H. , Holmes L. J. , Bardwell S. J. 
Published: May 2009

Variations in dry body weight in the Stage V copepodite, associated with the development of the winter generation of Calanus finmarchicus (Gunnerus) in the Firth of Clyde each year were observed from 1978 to 1982, during early October and the middle of January.The Stage V copepodite was dimorphic with respect to body size. Body weights of freeze-dried specimens were measured and form was distinguished using the prosome length. Allometric relationships of the dry weight to length in the two forms were similar, and stable between autumn and winter. From the mean of estimates for all collections, dry body weights of individual Stage V copepodites were proportional to the cube, approximately, of prosome lengths. Proportional coefficients were seasonally variable, but on all occasions these were greater for the large than the small form. Variations in dry weight were directly associated with the distinction between forms in body volume.Collections from October and January encompassed the period between the end of maximal Copepodite V recruitment and the onset of adult recruitment to the winter generation. Over this period, however, the dry body weight in all years decreased relative to length in Copepodite Stage V. This decrease, on average, was by 17% and 23% in the large and small forms respectively. Monthly collections from one population were used to examine these patterns in relation to the development of gonads. Stage V copepodites of both forms were increasing in dry weight during October, but from November were losing weight continuously. Maturation in the majority of these individuals was restrained throughout autumn, abruptly accelerating in winter.
The retial system of the locomotor muscles in the thresher shark
Authors: Bone Q. , Chubb A. D. 
Published: May 2009

The red muscle of the thresher-shark myotome is internalized and supplied by a simple rete in connexion with lateral vessels. It is probable that the system enables the fish to be warm-bodied.INTRODUCTIONWarm-bodied sharks were first described by Carey & Teal (1969); subsequent observations by Carey and his colleagues (Carey et al. 1971) and by Carey (1982) showed that five lamnid species were able to maintain body temperatures 5–10 °C above the ambient water. All of these possess more or less elaborate retia linking a red muscle mass lying internally in the myotomes with the systemic circulation. In cold-bodied sharks, the red muscle lies superficially, just under the skin, and retia are absent. A sixth lamnid species, the big-eye thresher shark (Alopias superciliosus) may be warm-bodied; it has a simple muscle retial system (Carey et al. 1971) which has not been described in detail. The chance capture of a common thresher shark (A. vulpinus) enabled this short description of the retial system in this species.
Observations on the temperature and salinity relations of Lasaea rubra
Authors: Davenport John , Beard Jane B. 
Published: May 2009

In direct-transfer temperature tolerance experiments, Lasaea rubra was found to have a median lethal low temperature of – 3.5°C and a median lethal high temperature of + 39°C. If introduced to temperatures slowly, survival at extreme temperatures was improved, particularly at freezing temperatures; > 92°0 of animals survived at – 10 °C and + 40 °C if introduction from a holding temperature of + 18 °C took place over at least 1 h.Lasaea rubra are active at salinities between 15 and 60‰, indicating considerable tolerance of changes in body fluid osmolarity. In week-long exposure experiments more than 50 % of animals survived all salinities from 0 to 150‰; tight shell valve closure was maintained at extreme salinities.When exposed to declining salinity, Lasaea rubra progressively isolates its tissues from the environment as salinities fall below 18–20‰, and maintains shell valve closure below 8‰. These responses are symmetrically reversed in response to rising salinity.Salinity discrimination in Lasaea rubra is based upon sensing of external osmolarity, not external ionic concentrations.
Recent Investigations into the Distribution of Regular Echinoids in the North Sea
Authors: Cranmer G. J. 
Published: May 2009

A major contribution to our understanding of the distribution and taxonomy of echinoids in British waters was made by Mortensen (1927, 1928–1951). Many earlier qualitative investigations (e.g. Süssbach & Breckner, 1911; Brattström, 1941) which dealt only with limited areas, were combined in Mortensen (1928–1951) to produce an overall assessment of the North Sea echinoid fauna.In his discussion paper Ursin (1960) synthesized findings from his 20 year grab sample survey with the work of others to produce a valuable quantitative analysis of the echinoids of the central North Sea (54–5 8° N).In recent years (1977–1983) participation on demersal fish surveys in the North Sea has enabled the distribution and population structure of the macroepibenthic component of the water column to be recorded (Dyeret al.1982, 1983; Cranmer, Fry & Dyer, 1984).Although this present study has added no new echinoid species to the fauna it has given a detailed picture of echinoid distribution in the area.
The Adsorption of Ions from Sea-Water by Sand
Authors: Stowell F. P. 
Published: May 2009

1. The ions present in sea-water are normally adsorbed by sand.2. Percolation of sea-water through sand causes a slight abnormality in the concentrations of calcium and magnesium ions, due to the fact that sand is not an inert adsorbing agent, but is capable of discharging calcium ions into the water in exchange for magnesium and sodium.3. The extent of adsorption and exchange is insufficient to cause hydrolysis and alteration in pH if the bulk of the sea-water is large.
Notes on the Biology of some Lamellibranchs in the Clyde Area
Authors: Stephen A. C. 
Published: May 2009

The paper deals with four species from the Clyde Area, namely: Tellina tenuis, Tellina fabula, Abra alba, and Cardium edule.T. Tenuis.1. The growth at one station below L.W.M. in Kames Bay is considered. This is slower than in any other part of its vertical range.2. Heavy spat-falls were recorded in 1926 and in 1930, but, in both cases, the spat grew slowly and died off quickly at the stations below L.W.M.3. The general rate of growth for the species from its upper to its lower limit of distribution in Kames Bay is tabulated.
Observations on the Fauna and Constituents of an Estuarine Mud in a Polluted Area
Authors: Fraser James H. 
Published: May 2009

1. An ecological survey of the fauna of Dingle Beach, Mersey Estuary, has been made.2. A detailed analysis of the constituents of the mud, sand and gravel is given.3. A quantitative analysis of the Molluscan fauna from a series of stations has been made.4. Type of ground and fauna at different tidal levels are correlated.Mya arenaria is only found in abundance where there are stones. Macoma balthica is abundant wherever there is thick mud.5. Dingle Beach is a type of Macoma community but differing markedly from the typical community described by Petersen as “d”.6. The importance of sewage in producing silt and the part played by sewage in the food chain are discussed.
The Determination of Nitrate in the Sea by Means of Reduced Strychnine
Authors: Cooper L. H. N. 
Published: May 2009

The recent criticism of Thompson and Johnson (7) of the method of determining nitrate in the sea by means of reduced strychnine is held to be unsound.Preparation of the reagent given due care and pure materials has offered little difficulty.A possible method for the preparation of nitrate-free sulphuric acid is outlined.The effect of iodate in concentrations likely to be met in the sea is negligible.Interference by organic material has been avoided by first centrifuging all samples obtained during periods of plankton activity.The relative intensity of colour given by nitrate and by nitrite nitrogen is discussed.
Nitrate in Sea-water and its Estimation by means of Diphenylbenzidine
Authors: Atkins W. R. G. 
Published: May 2009

1. The diphenylbenzidine reaction of Letts and Rea has been examined and is recommended for use in sea-water; 2·5 ml. of sea-water is mixed with 6·0 ml. of the purest strong sulphuric acid and then allowed to cool. Subsequently 1·5 ml. of a sulphuric acid solution of diphenylbenzidine is added, the concentration being 20 mg. per 100 ml. of acid. The colour should be compared, after 20-24 hours, with a standard solution made up by adding a definite quantity of nitrate to the sea-water. A blank correction should be used. Diphenylbenzidine used must be recrystallised from boiling toluene.2. If the sulphuric acid used is found to give a blue colour with diphenylbeniddine, this may be removed, if not too intense, by warming the acid for a few minutes. With a more intense blue the nitric acid-present may be eliminated by previous cautious treatment with hydrogen sulphide. Phosphoric acid may be used instead of sulphuric acid with fresh water, but not with sea-water.
The Development of Nereis pelagica Linnæus
Authors: Wilson Douglas P. 
Published: May 2009

Larvæ of Nereis pelagica Linnæus were reared from the egg, and the young worms, which developed from them, to the age of one year.The larvæ from an early stage possessed three chætigerous segments. At first after hatching they swam strongly by means of a prototroch, an akrotroch and three paratrochs, but as the cilia gradually disappeared they crawled more and more, finally abandoning swimming altogether.The head developed a pair of tentacles anteriorly and a pair of palps ventrally. A pair of tentacular cirri arose posterior to the prototroch and a little later a second pair ventral to them.The first pair of parapodia lost their bristles, and a lobe which had grown out between the noto- and neuropodial chæta-sacs became a third and posterior pair of tentacular cirri. Much later a fourth pair developed ventral to them.About the time when the larvæ ceased to swim (18.days old) a fourth pair of larval parapodia (third adult pair) appeared, to be followed by a fifth, sixth, etc. At sixty-five days old worms had about twentyone pairs of parapodia, at one year they had sixty and were then about 1-5 cm. long.During larval development a constant succession of bristles was seen. In the earliest stages the bristles were mainly homogomph spinigers with long appendices; later these fell out and were replaced by homogomph and heterogomph falcigers with shorter appendices. Later still these were replaced by bristles of the adult type.It is pointed out that these larvæ differed from those which Herpin reared in that they hatched earlier and instead of crawling as soon as liberated they swam for several days by means of their ciliated girdles.
Mechanisms Of Resistance to Polychlorinated Biphenyls (PCB) in Two Species of Marine Diatoms
Authors: Cohen Melissa K. , West Anne S. , Cosper Elizabeth M. , Wurster Charles F. 
Published: May 2009

Clones of Ditylum brightwellii and Thalassiosira nordenskioldii were isolated from New York coastal waters, and PCB-resistance in D. brightwellii was induced in the laboratory by exposure to increasing concentrations of PCB. Resistance could not be similarly induced in T. nordenskioldii, but was serendipitously discovered in unexposed cultures that had undergone sexual reproduction.Cells of the resistant strain were substantially larger than those of the sensitive strain in both species. Larger vacuole space seemed to account for this in D. brightwellii, but in T. nordenskioldii larger cells contained more carbon. Experiments with14C-PCB tracer indicated that PCB accumulation was less in resistant strains of both species. Neutral lipid content per cell, as determined using the fluorophore Nile Red, was similar for resistant and sensitive strains of both species. Sub-cellular examination of lipid droplets in D. brightwellii suggested that the PCB-resistant strain may be sequestering this lipophilic toxicant in a location removed from physiological activity. In T. nordenskioldii a decreased ratio of neutral lipidxarbon may reduce intracellular accumulation of PCB. These diatom species have developed PCB resistance in the highly PCB-polluted Hudson River estuary and, since they are the preferred food of dominant copepods, they may offer less PCB per unit ration to zooplankton grazers.
Population Biology of Liocarcinus Depurator (Brachyura: Portunidae) In Mussel Raft Culture AreasIn The Ría De Arousa (Galicia, Nw Spain)
Authors: Fernández L. , González-Gurriarán E. , Freire J. 
Published: May 2009

The population biology of the crab Liocarcinus depurator was studied for one year in the mussel raft culture areas of the Ria de Arousa. The density and biomass of this species is much higher in the raft areas, especially in the outer part of the ria, than in the central channel area. Maximum abundance occurred during the winter months (up to 8-80 g wet weight m and 0-44 individuals m.Maturity size in females was set at 28-30 mm carapace width, (based on ovigerous females) and is attained in the first year of life. The ovigerous females were most abundant in January (approximately 70% of the mature females), but another less important maximum value was observed in May, attributable to a second spawning. Modifications in the sex ratio from 1:1 affected individuals larger than the maturity size during the season when there was a greater number of ovigerous females present. Data on sex ratio and breeding cycle indicate that ovigerous females move towards the raft areas located in the outer part of the ria. Trawl recruitment took place in the stations located in the outer Ria, and mainly in August-September, although it continued to a lesser extent in autumn.The Von Bertalanffy growth function was fitted to both sexes in the two outer stations. Growth rate was higher in males than in females, while variability between stations was less important. However the growth rate and reproductive output of L. depurator in the Ria de Arousa was higher than in populations from other geographical areas, possibly because of the availability of food from the rafts and or the oceanographic conditions in the ria.