bluuebunny/crossref_metadata_2025_split huggingface dataset:
Further Experiments on the Fertilization of a Sea Loch (Loch Craiglin). The Effect of Different Plant Nutrients on the Phytoplankton
Authors: Marshall S. M. , Orr A. P. 
Published: May 2009

Loch Craiglin cannot be considered as merely an isolated basin of Loch Sween. Its shallowness, the great growth of vegetation round the shore and the fluctuations in salinity make it atypical. On the more complete isolation of the loch with the making of the dam, these conditions led to a lack of circulation, a consequent development of hydrogen sulphide in the deep water and very high pH values near the surface. One could not therefore expect the plankton to be very similar to that in the outside loch (see, however, Marshall, 1947). Unfortunately there are no records of seasonal variation before fertilization was begun. In spite of these drawbacks Loch Craiglin was a convenient and manageable area for small-scale experiments on fertilization.The experiments may be divided into two groups, those which were not followed up in detail and those in which the plankton and hydrographic results were followed from day to day. The former, made during the earlier stages of the work, are mainly described in the previous papers and led to the conclusion that the richness in phytoplankton of Loch Craiglin in 1943 was probably caused to a large extent by fertilization. Those of the second group, described above, were made to test special points and different fertilizers. Two experiments made during the summer of 1944 had apparently no effect on the phytoplankton but a third in which a very large excess of fertilizer (ten times the normal quantity) was added, gave a good increase after an initial lag. At that time the attached algae were abundant and their needs apparently had to be satisfied before any nutrients could be used by the phytoplankton.The remaining experiments, which were therefore made during the winter, showed that commercial ammonium sulphate, ammonium nitrate and monoammonium phosphate could replace the sodium nitrate and superphosphate used hitherto. Two further experiments in the following spring using ammonium chloride and urea did not, however, prove effective. All the salts used had been found in laboratory tests by Miss F. A. Stanbury to be suitable for diatom growth, and the reason for the failure of these two in the loch is unknown.The utilization of the nutrients was extremely rapid even in winter but it is probable that their disappearance is not entirely caused by the phytoplankton or bottom-living algae but partly by adsorption on the bottom mud or by suspended matter. On one occasion it may have been caused by a serious fall in loch level.The zooplankton which during the first year of fertilizations was richer in Loch Craiglin than in the outside loch diminished in the second year and remained poor thereafter in spite of, or perhaps because of, the intensive fertilizations. The dense phytoplankton and other vegetation raised the pH at times to levels dangerous to animal life.
The Ecology of the Amphipoda of the South of the Isle of Man
Authors: Jones N. S. 
Published: May 2009

A survey was made during 1946 covering the Amphipoda of the south end of the Isle of Man from an ecological aspect. The object was to revise the records of the area and to obtain additional information about the habitats of the species found.The area in which the survey took place was within a radius of 10 miles from Port Erin.Various sorts of gear were used for collection offshore and it is concluded that the fine-meshed dredge is the most useful instrument for collecting amphipods.A systematic treatment of the species found includes a summary of records regarding habitat for each species.It is suggested that the Amphipoda may be of greater economic importance than has previously been realized.A discussion of offshore, intertidal, and brackish-water habitats includes lists of the more important species obtained grouped according to type of ground and zonation with regard to tidal level and salinity. The importance of offshore species is assessed on a basis of the average number of individuals collected per haul.Comparison of the zonation of littoral and estuarine species with that known from other areas reveals a general agreement.The existence of more than one form of several species of the genusGammarusis discussed and it is suggested that they are in an active state of evolution.I am indebted to Prof. J. H. Orton for encouragement and discussion, and to Mr G. M. Spooner for allowing me to read a proof of his recent paper.
Methods of Identification of the Larvae of Balanus Balanoides (L.), B. Crenatus Brug. And Verruca Stroemia O. F. Müller
Authors: Pyefinch K. A. 
Published: May 2009

A description is given of characters which allow the larval stages of Balanus balanoides, B. crenatus and Verruca stroemia to be identified rapidly.It is emphasized that the characters used in this method of identification are only valid for these three species inter se, further work on similar lines for other species may reveal difficulties not apparent in the present scheme.
Feeding in some monogenean skin parasites: Entobdella soleae on solea solea and Acanthocotyle Sp. on Raia clavata
Authors: Kearn G. C. 
Published: May 2009

Entobdella soleae, a monogenean skin parasite of the common sole was induced to feed on its host. The feeding organ (,pharynx-) is protruded during feeding and encloses a circular area of host skin. The gland cells in the feeding organ produce a proteolytic secretion which digests the epidermis of the fish. The liquid food is then pumped by the feeding organ into the intestinal diverticula, where it is absorbed.Acanthocotyle sp. from the skin of an elasmobranch fish, Raia clavata, feeds on epidermis in the same way as Entobdella soleae. Observations on other skin and gill-parasitic monopisthocotylineans indicate that the majority of them are epidermis feeders, although there is evidence that some gill parasites, for example Amphibdella torpedinis, may feed on blood.The evolution of parasitism in the Monogenea is tentatively attributed to the outstanding qualities offish epidermis as a food for a potential ectoparasite and in particular to its rapid rate of regeneration.
The age and growth of the scallop, Pecten maximus (L.), in Manx waters
Authors: Mason James 
Published: May 2009

Growth-rings on the shell of the scallop (Pecten maximus) are laid down annually, in spring, and so can be used to determine the age.Scallops grow from spring to December, and cease growing in winter. The resumption of growth in the spring is marked by the appearance of the annual growth-ring at the edge of the shell.The first year's growth is of one of two types. A few scallops have shells which show a large first year's growth, 28 mm or more wide, while the great majority have shells which show a small first year's growth, less than 28 mm wide. These two types probably depend on the two principal spawning periods of the scallop, most of the former arising from the spring spawning and most of the latter from the autumn one.The growth curve of P. maximus is of a type characteristic of lamellibranch shells. The annual growth is greatest in the first two or three years of life, after which it decreases steadily.Scallops grow more quickly in shallow water than in deeper water.Possible causes of the annual cessation of growth are discussed.A paucity of young scallops was noted in the dredge samples, as previous workers have reported. No reason can be given.
The fishery for crawfish, Palinurus elephas, off the coast of Cornwall
Authors: Hepper B. T. 
Published: May 2009

Off the coast of Cornwall from the Lizard Head to Padstow there has been, for many years, a small but locally important fishery for crawfish Palinurus elephas (Fabr.).The fishermen had used pots and tangle nets up to the outbreak of the Second World War in 1939. From 1945 tangle nets had been little used and the fishery was pursued mainly by pot fishermen until the early 1960s when divers using self-contained under-water breathing apparatus began to collect crawfish. Tangle nets were re-introduced widely in the late 1960s.
Observations on the opisthobranch mollusc Acteon tornatilis (L.).
Authors: Fretter Vera , Graham Alastair 
Published: May 2009

SummaryActeon tornatilis is an opisthobranch mollusc which burrows in sand, using foot, labial and cephalic tentacles in the process. The last also help to exclude sand from the mantle cavity, which is extended into a caecum coiling alongside the visceral hump, presumably used for respiration but also for excretion. The main pallial water current is an exhalant one on the right.The mantle skirt carries, on the left, numerous repugnatorial glands with toxic secretions.Labial glands lie at the mouth and the buccal cavity contains jaws and a reduced buccal mass and radula. Into it open salivary glands the structure of which is like that of the pyramidellids. The oesophagus shows traces neither of glands nor of torsion whereas the stomach, though simplified, has resemblances to that of a prosobranch.The reproductive system is shown to be different from previous descriptions. Male and female ducts are separate from the lower end of the little hermaphrodite duct. The former passes to a prostate from which a vas deferens leads to a large uninvaginable penis; the latter has associated albumen and mucous glands and there is a receptaculum seminis to the duct of which a ventral channel leads from the female aperture in the mantle cavity.Discussion of these aspects of the animal's structure confirms its position as the most primitive of the opisthobranchs.
The position of Pontophilus echinulatus (M. Sars) in the Crangonidae
Authors: Lebour Marie V. 
Published: May 2009

On 26 November 1953 the new research ship Sarsia on her first cruise collected a number of Pontophilus echinulatus (M. Sars) (with an Agassiz trawl, depth 100 fm., La Chapelle, Bay of Biscay). Mr G. R. Forster, of the Plymouth Laboratory, noted that these did not fit into the key given by Kemp (1910) in that they have in the male a distinct appendix interna at the base of the four last pairs of pleopods, while in the female this is absent, the inner ramus being usually undivided, although occasionally an indistinct division can be made out. Otherwise they agree with Kemp's diagnosis.Kemp (1910) notes M. Sars 1861 as authority, but this is only a preliminary description. In Sars (1868), given in Kemp's (1910) bibliography but not under the species, it is seen that he describes both male and female exactly as in the specimens from Sarsia, the male having a distinct appendix interna on the last four pairs of pleopods and an appendix masculina also on the second pair, the female pleopods having very short inner rami, except in the first which is long, and there is no appendix interna. Sars's figures of these limbs are very good. Kemp (1911) joins Philocheras with Pontophilus, and in this he is now followed by most authors.Kemp (1916) reviewed the pleopods in the genus Pontophilus, as far as he could with the material he had in India, and he proposed certain groups according to the presence or absence of the appendix interna.
Protostyela heterobranchia n.gen., n.sp., a styelid ascidian from the scottish west coast
Authors: Millar R. H. 
Published: May 2009

SummaryProtostyela heterobranchia n.gen. n.sp. is a compound styelid ascidian from Scottish waters. The branchial sac has three longitudinal bars on each side and no folds, and the stigmata are transverse. Both hermaphrodite and unisexual (male) gonads are present.
The breeding and development of the ascidian Pelonaia corrugata Forbes and Goodsir
Authors: Millar R. H. 
Published: May 2009

SummaryPelonaia corrugata in the Firth of Clyde breeds for only 2–4 weeks in January or February. The species is oviparous. Early cleavage is similar to that of other ascidians, but after gastrulation the embryo passes through a two-hemisphere stage. One of these hemispheres is endodermal. From the other hemisphere, which slowly envelops the endoderm, two ampullae grow and fix the embryo to the substratum. The young ascidian develops directly from this attached embryo, and the development is therefore anural. Elimination of the pelagic larval stage is regarded as an adaptation to the sand-dwelling habit of the adult, as it prevents dispersal to unsuitable habitats.
Innervation of an amphipod heart
Authors: Alexandrowicz J. S. 
Published: May 2009

SummaryIn the heart of Marinogammarus marinus three systems of nerve elements have been found, viz. (1) a local system consisting of a ganglionic trunk situated on the dorsal surface of the heart and sending branches to the muscle fibres, (2) two paired nerves, termed the 1st and 2nd cardiac nerves, connecting the local system with the central nervous system, and (3) nerves supplying the muscles of the arterial valves. It is assumed that the local system rules the beat of the heart and that the cardiac nerves have a regulating function.Not directly connected with the heart, but having relation to the blood circulation are two sets of nerves: (1) nerves supplying the alary muscles, presumably regulating the pressure in the pericardial cavity, and (2) nerves spreading over the lateral wall of the pericardium in neuropile-like plexuses and supposed to have a neurosecretory function.It is suggested that the centre controlling the blood circulation could be localized in the infraoesophageal ganglion.
A marine fungus Plectospira dubia n.sp. [Saprolegniaceae], infecting crustacean eggs and small Crustacea
Authors: Atkins D. 
Published: May 2009

SummaryA marine fungus, Plectospira dubia n.sp., has been found infecting crustacean eggs and small Crustacea in the Plymouth Laboratory. It has the following characteristics: mycelium mostly intra-matrical, coarse, hyphae 50–100µ in diameter. Sporangia irregularly inflated, emptying by efferent hyphae of variable length and frequently of irregular diameter; sometimes proliferous; wall persistent. Zoospores dicystic and dimorphic, but the first swimming stage largely suppressed, the first zoospores mostly encysting within the sporangium after a short period of feeble activity, then swimming in the second stage. The first zoospores pyriform and flagellate (probably biflagellate): in the second motile stage laterally grooved with two laterally inserted flagella. First zoospores about 1oµ long, when encysted 7–8µ in diameter; in the second motile stage 11–12µ long, when encysted 6–7µ. in diameter. Gemmae numerous, spherical, up to 1OOµ. in diameter. Sexual organs so far unknown.
Biologically active compounds in the sea
Authors: Johnston R. 
Published: May 2009

SUMMARYThe concept of external metabolites in the sea, which has received support from biological investigations, invites chemical corroboration which, until recently, has not been forthcoming. Separations of organic matter from filtered sea water using a variety of methods are reported and a preliminary assessment made. Organic residues obtained from different open sea sources by adsorption on carbon give rise to different paper chromatogram patterns. Certain organic components of a carbon adsorbate contain substances which affect the growth of a number of marine phytoplankton organisms. Further research is planned employing methods of isolation and chromatography of the dissolved organic matter from different sea waters and the assessment of biological activity of certain fractions by means of common marine organisms. Some aspects of the significance of biologically active compounds in the sea are mentioned.
The salp Ritteriella off the English coast—a correction
Authors: Fraser J. H. 
Published: May 2009

In a recent short note in this Journal (Fraser, 1954) the occurrence was announced, off the entrance to the English Channel, of the solitary form of the salp Ritteriella picteti (Apstein), and seven aggregate forms of R. amboinensis (Apstein), taken by H.M.S. Challenger in 1953. The identification of the aggregate forms as R. amboinensis and not as R.pictetiv/as based, as then stated, on Thompson's (1948) description from a very young specimen of R. picteti which emphasized the similarity of its muscle arrangements to those of Salpa cylindrica and not to Ritteriella amboinensis.Since this was written, Berner (1954) has described the aggregate form of R. picteti from good specimens found off the west coast of U.S.A., and he has shown that the musculature was in fact not like that of Salpa cylindrica but very similar to Ritteriella amboinensis. Differences were noted in the number of fibres constituting the various body muscles and in the number and arrangement of the oral muscles. A still more recent paper by Yount (1954) includes comparisons of the two forms, based on Berner's characters but also including differences in the length of the endostyle and in body shape (length of anterior and posterior processes, and degree of extension of the gut outside the rest of the body). Yount also goes into greater detail in describing the oral musculature in tie two species.A re-examination of the specimens taken by H.M.S. Challenger shows them to be in fairly close agreement with both Berner's and Yount's descriptions of R. picteti, but with one or two small differences. The actual number of fibres in the muscles is rather smaller than given by Berner for R. picteti, though the precise figure is difficult to ascertain, and there is no median interruption of the first sphincter muscle in the upper lip which Berner believed to be characteristic, and which Yount accepted.
Carotenoid pigments in the optic cushion of Marthasterias glacialis (L.)
Authors: Millott Norman , Vevers H. G. 
Published: May 2009

SUMMARYThe optic cushion of Marthasterias glacialis is seen to contain yellowish orange and reddish orange pigments. The former occurs throughout the cushion, the latter is confined to the wall of the optic cups and a few scattered, irregular patches. Both pigments occur in the cytoplasm of long and narrow or irregular cells, some in the form of granules or vacuoles.Optic cushions yield an orange extract in methanol which decomposes in light.The behaviour of methanolic extracts after partitioning, saponification, chromatographic separation and spectrophotometric examination indicates the presence of β-carotene and esterified astaxanthin.The significance of the results in relation to previous findings and their possible bearing on photoreception is discussed.
The growth rate of the Long Rough Dab Hippoglossoides platessoides (Fabr.)
Authors: Bagenal T. B. 
Published: May 2009

SUMMARYThe ages of 1426 female, and 135 male Long Rough Dabs have been determined from otolith readings. The females were found to live into their seventh year and reach 30.5 cm, compared with males that live to their fifth year and reach 19.0 cm in length. However, the mean increase in length per year for a given length, has been found to be the same. The growth of the females has been shown to fit the equation lt=26.437 (I—0.574t) and of the males lt=17.754 (I —0.585t). In the case of the females the observed and calculated values agree quite closely, but with the males there is a greater difference, and it is believed that the discrepancy is due to net selection. The suggestion is made that the calculated mean lengths for each age group are better estimates of those of the population than are the observed sample means. The two standard deviations limits can be estimated about the population means and the sample values are found to be within these limits.Comparison with previous studies shows that the Clyde fish are smaller and shorter-lived than more northern specimens, though broadly speaking the rate of growth for comparable ages is not so dissimilar.
The feeding behaviour of starfish on Essex oyster beds
Authors: Hancock D. A. 
Published: May 2009

SUMMARYLaboratory and field observations were made on the food and feeding of the starfish in relation to its role as a predator on oyster beds in the rivers of Essex, particularly in the river Crouch.Asterias rubenswas found most likely to be associated with large numbers ofCrepidula, the most serious competitor of the oyster.Laboratory experiments showed that althoughAsteriasoccasionally ate spat and adult oysters, the greater part of its food was made up of organisms which are competitors of the oyster. The smaller sizes ofAsteriasate large numbers of barnacles, with occasional spat of oysters andCrepidula. The larger occasionally ate oysters and oyster spat, but almost always exhibited a preference for mussels and, in the absence of these, forCrepidula, and sometimes even forUrosalpinx.Some observations were made on the method and rate of feeding and distribution ofAsteriasandSolaster papposus, and certain aspects of the feeding behaviour of the stone crab,Hyas araneus.It was concluded thatAsteriasis not such a serious enemy of the oyster as was previously supposed, and that under certain conditions, its presence may be beneficial to oyster culture.
The diet and feeding mechanism of Idotea
Authors: Naylor E. 
Published: May 2009

SUMMARYIdotea feeds on large food masses. It is potentially an omnivorous scavenger, but each species may have a characteristic diet depending on the availability of food in its particular habitat.The structure, topography and action of the mouthparts are described: spines on the maxillules and maxillipedes scrape the food material whilst the mandibles actually bite the food; toothed spines on the maxillules and mandibles push the food upwards to the molar processes of the mandibles; debris is brushed forwards between the lobes of the paragnath by setae on the inner endites of the maxillules, maxillae and maxillipedes; and spines on the maxillipedal palp, and on the first leg, comb the mouthparts.The structure of the foregut resembles that of Asellus and Ligia.The relation of the feeding mechanism to the functional evolution of the mouthparts of Peracarida as a whole is discussed.
Annual Variations in Length of Copepods in the Sargasso Sea off Bermuda
Authors: Deevey Georgiana B. 
Published: May 2009

SUMMARYMeasurements of cephalothorax length were made on the females of five species of oceanic copepods for the period from January 1958 through August 1959. The seasonal length variations of the three species of Pleuromamma (P. piseki, P. abdominalis and P. xiphias) followed the cycle in total phytoplankton. Significant positive correlations were obtained between the mean lengths of P. abdominalis and P. piseki and the mean quantity of phytoplankton of the month previous to sampling, but there was no correlation between length and temperature.The seasonal length variations of females of Haloptilus longicornis and Lucicutia flavicornis differed in pattern from that of the Pleuromamma species and no correlation was found between their mean lengths and the annual cycles of phytoplankton or temperature. These species may feed selectively on some possibly unmeasured fraction of the plankton or on particulate organic matter.Previous work has shown that in waters with a wide temperature range there is a high negative correlation between length and temperature and no correlation between length and phytoplankton. In other regions with an intermediate temperature range the sizes of successive generations of copepods are correlated to almost equal degree with the temperature and the quantity of phytoplankton available during growth. In the Sargasso Sea, where there is a narrow temperature range but a definite seasonal cycle in total phytoplankton, the length variations of the Pleuromamma species are correlated with the phytoplankton cycle and not with temperature.