bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Quantitative Method for Estimating the Periodicity of Diatoms
Authors: Aleem Anwar Abdel 
Published: May 2009

The method described below was evolved as a substitute for counting, which is unsatisfactory for epiphytic marine diatoms. It depends upon the estimation of the amount of diatom-silica associated with unit dry weight of the sub-stratum. The sea-weed samples are first freed from sand particles and are then treated with strong nitric acid in the usual way. In order to convert the insoluble silica of the diatoms into a soluble form suitable for chemical estimation, the material is fused in a platinum crucible with a mixture of K2CO3 and Na2CO3 and the fused mass is dissolved in (silica-free) distilled water and filtered. The amount of silica in the filtrate is determined colorimetrically according to the method of Dienért and Wandenbulcke (cf. Atkins, 1926). The method is simple in practice and saves considerable time and labour. The full procedure is illustrated by reference to a study of the periodicity of Grammatophora marina (Lyngb.) Kütz. at Swanage, Dorset.This species (PL. I) is found all the year round on Cladophora rupestris in a pit in one of the reefs at Peverel Point, Swanage. In summer it is the only epiphytic diatom on the Cladophora, while in spring and autumn small numbers of other epiphytes (Cocconeis, Opephora, Rhoicosphenia) are present. In order to obtain a fairly representative picture of the abundance of Grammatophora at different times, samples of the Cladophora were collected monthly from a definite area in the pit, each including 3–4 cm. of the apices of five to ten Cladophora tufts cut at random.
The Occurrence of British Aplysia
Authors: Grigg Ursula M. 
Published: May 2009

On 13 November 1947 a specimen of the sea hare, Aplysia depilans L., which had been trawled in Babbacombe Bay, was sent to the Plymouth Laboratory. When it was realized that the animal was not the common A. punctata Cuv., collecting trips to likely places were undertaken in the hope of finding more. No others were found, but on one of the expeditions Dr D. P. Wilson picked up a specimen of A. limacina L.Both A. depilans and A. limacina are found in the Mediterranean and on the west coast of Europe: A. depilans has been found in British seas before, but so far as is known A. limacina has not.These occurrences provide the main reason for publishing this study. The paper also includes an account of the distribution of aplysiids in British waters and a review of the controversy over the identity of large specimens. As the animals are not usually described in natural history books, notes on the field characters are added.I would like to thank the Director of the Plymouth Laboratory for affording me laboratory and collecting facilities and for his interest in the work. I am most grateful to Dr G. Bacci, who went to much trouble to send me specimens from Naples; to Dr W. J. Rees, who arranged for me to have access to the British Museum collection; to Dr D. P. Wilson, who has provided the photographs of A. punctata (Pl. I) and A. limacina (Pl. II); and to D. J. Slinn, who prepared the map.
Studies on the Growth of Marine Phytoplankton I.Asterionella Japonica Gran
Authors: Kain Joanna M. , Fogg G. E. 
Published: May 2009

A planktonic marine diatom, Asterionella japonica, has been grown in unialgal, but not bacteria-free, culture under controlled conditions and its growth has been measured by means of optical density determinations and cell counts in combination.The relative growth constant has been found to be usually between 0·7 and 1·2 loge units per day, and to be little affected by variation of the concentration of nitrate, phosphate and silicate within wide limits. Rapid growth occurred in waters having salinities between 20 and 40‰ S. The optimum temperature for growth was 20–25° C and the optimum light intensity from 4000 to 10,000 lux. The relative growth rate was affected most markedly by variation in hydrogen-ion concentration. This was manifest in stagnant cultures in which the rise of pH above 8·3, caused by absorption of carbon dioxide, resulted in the inhibition of growth. This could be countered by increased aeration or by the addition of the buffer tris(hydroxymethyl)aminomethane.Evidence has been obtained which suggests that A. japonica requires a thermostable substance present in natural sea water and that a thermolabile substance stimulating its growth is produced in culture.Final yields of the order of 4000 cells per mm3 were obtained and, within limits, were dependent on the amounts of nitrate and silicate supplied. The nitrogen requirements per cell was determined as 0·255 μμg atom. Indications were obtained of the presence of a growth-inhibiting substance in the filtrates from old cultures.The optical density of the cells was increased at high nitrate concentrations and when exhaustion of silicate prevented cell division.
On the Biology of Calanus Finmarchicus X. Seasonal Changes in Oxygen Consumption
Authors: Marshall S. M. , Orr A. P. 
Published: May 2009

The seasonal changes in the respiration of Calanus are considerable and are, on the whole, related to size and therefore to weight. Length alone is not enough to account for the differences since ripe females, although the same length as unripe, have a markedly higher respiration. In addition, by taking samples of large and of small Calanus of a single stage, it was shown that the difference in respiration was small. Neither is weight by itself enough to account for the difference between groups. Stage V Calanus are, for a given length, heavier even than ripe females and yet their oxygen utilization is low. In this instance, however, an important part of the weight consists of fat which is a food reserve and not actively metabolizing. The difference of weight between ripe and unripe females is not known, but ripe females must be heavier and this will account for their higher oxygen consumption.Although the oxygen and therefore the food required during the spring months is high, at that time the phytoplankton is at its maximum and is probably sufficient to fulfil all needs. Egg-laying depends on the food supply and it is then that Calanus starts breeding. In winter, on the other hand, the Calanus is present as Stage V and oxygen consumption is little more than half what earlier figures suggested. No ‘hibernation’ seems to take place but the population is living in an economical way for Stage V use little oxygen, live in deep water and do not undertake diurnal vertical migration.At 10° C ripe female Calanus will require daily from 3·9–7·2% of their body weight as dry matter in summer and from 2·8–6·7% in winter. Stage V will require 2·3–3·1% in summer and 1·4–3·3% in winter. The higher values are for carbohydrate and the lower for fat.It is difficult to believe that Calanus in winter will be able to find enough food by filtration alone. The fact that in the winter months it depends more on predation may account for its survival.
The Distribution of Gas and Liquid within the Cuttlebone
Authors: Denton E. J. , Gilpin-Brown J. B. 
Published: May 2009

The newest chamber of a cuttlebone is always incomplete and full of a watery solution. This contains sodium and potassium in concentrations close to those of sea water.The second newest chamber contains a gas space and sometimes contains liquid. This liquid is rarely localized at the siphuncular end of the chamber. It is not certain that liquid is initially extracted through the siphuncular wall of the chamber, although this is possible.When liquid is pumped out of a newly formed chamber the salt which it initially contains is not left behind, either free or bound into the structure of the bone.The 3rd to about the 10th newest chambers usually contain no visible liquid. But their siphuncular walls are permeable to liquid and liquid does enter these chambers when the cuttlebone becomes very dense.At cuttlebone densities around 0·6, i.e. close to values which will make the cuttlefish neutrally buoyant, the older and more posterior chambers are almost full of liquid. This liquid can, however, be pumped out. When a cuttlebone has a density around 0·5 very little liquid can be seen in any of its chambers.The pressure of gas within a newly ‘pumped out’ chamber is very low, but by the time a chamber has become the ninth newest the pressure of gas is close to the average value for the whole cuttlebone, i.e. about 0·8 atm.The low pressure of gas found in the newest chambers is explained by the slowness with which gas diffuses into a space created by the active removal of liquid.
The Functional Morphology of the British Species of Veneracea (Eulamellibranchia)
Authors: Ansell Alan D. 
Published: May 2009

The functional morphology of twelve British species of the Veneridae is described. The systematic position ofMysia undataand evolution within the Veneracea are discussed.Structurally, the members of the family Veneridae show a lack of special adaptations. The ability to move horizontally as well as ventrally in soft substrata is retained; the pedal gape is large and the foot well developed. The siphons are relatively short and fused. The food-collecting mechanisms of the mantle cavity are largely unspecialized and function in maintaining a considerable flow of water, and retaining as much as possible of the suspended material. Members of the Veneridae show a considerable uniformity of structure, but trends of evolutionary change may be distinguished. The generaGafrariumandCallistaare least specialized. The genusDosiniahas evolved along an independent line and is specialized by the possession of a stream-lined, circular shell, deep lunule, and greatly elongated siphons, for a relatively deep-burrowing habit. Within the superfamily Veneracea major lines of adaptive evolution have given rise to the rock-boring Petricolidae and the deep-burrowing Glaucomyidae, and the generaVenerupisandIrusshow affinities with both these families.
The Hydroid of the Anthomedusa Bougainvillia Britannica
Authors: Edwards C. 
Published: May 2009

The hydroid of the Anthomedusa Bougainvillia britannica Forbes has not been known with certainty, though its identity with B. flavida Hartlaub has appeared probable.From colonies found on Aporrhais pespelecani in the Firth of Clyde medusae of B. britannica have been reared. A description and figures of the hydroid and the young stages of the medusa are given.Bougainvillia flavida Hartlaub and B. linearis (Alder) are junior synonyms of B. britannica Forbes.
Observations on the Biology of the Marine Oligochaete Tubifex Costatus
Authors: Brinkhurst R. O. 
Published: May 2009

Tubifex costatus is a marine euryhaline species of tubificid, commonly found in brackish water. It is common in estuaries, where it colonizes a wide variety of substrata.The species breeds sexually once a year in early summer, and it is likely that it takes 2 years to reach maturity, and after breeding it dies.There is only one likely predator, Nereis diversicolor, and the population of T. costatus seems to be kept at a very constant level.
Some Aspects of Ionic and Osmotic Regulation inTisbe[Copepoda, Harpacticoida] in Relation to Polymorphism and Geographical Distribution
Authors: Battaglia B. , Bryan G. W. 
Published: May 2009

Ability to tolerate low salinities has been compared in homozygous adult females of thetrifasciataandviolaceaforms of the polymorphic copepodTisbe reticulatafrom Chioggia (lagoon of Venice). Both forms appear to be equally capable of tolerating sea-water concentrations of between 100 and 33 %. Further comparison with thetrifasciataform ofT. reticulatafrom Plymouth and with three different geographical populations ofTisbe furcatahas shown that these copepods are rather less tolerant.A study of ionic regulation using the isotopes22Na,42K and137Cs has shown that in diluted sea waterT. reticulatadoes not control the body Na concentration but does control the K concentration. Exchange rates for42K and137Cs are higher in theviolaceathan in thetrifasciataforms ofT. reticulatafrom Chioggia and the difference may have an adaptive nature although its significance is not clear. With regard to42K, the difference between the two polymorphic forms from the same population ofT. reticulatais greater than that between the three different geographical populations ofT. furcata. This serves to add more emphasis to the fact that colour polymorphism inT. reticulatacan be associated with other processes.
On Scyphomedusae of the Genus Pelagia
Authors: Russell F. S. 
Published: May 2009

The characteristics of the genus Pelagia are discussed.It is concluded that two good species, P. noctiluca (Forskål) and P. flaveola Eschscholtz, are already described.A third species P. colorata n.sp. has been erected for the medusa recorded from time to time from the coast of California which has been reported previously as P. noctiluca var. panopyra.
Observations on the Effects of Changes of Hydrostatic Pressure on the Behaviour of Some Marine Animals
Authors: Rice A. L. 
Published: May 2009

An apparatus and experimental method for the investigation of the effects of changes of pressure on the behaviour of marine animals is described.In 43 of a total of 53 species examined in this apparatus definite responses to abrupt pressure changes of 1000 millibars or less have been observed, increased pressure generally causing increased activity and movement upwards or towards the light, and decreased pressure causing decreased activity and movement downwards or away from the light. The relative importance of light and gravity in the orientation of these movements is generally correlated with the degree of development of the light and gravity receptors in the species concerned.The possible significance of these pressure responses in nature is discussed and it is suggested that pressure may be an important factor affecting the distribution of marine plankton, particularly during the hours of darkness.
On the Biology of the Whiting, Gadus Merlangus, in Manx Waters
Authors: Nagabhushanam A. K. 
Published: May 2009

The biology of whiting in Manx waters has been investigated at different stages of the life-cycle, with special reference to their diet. Planktonic postlarvae occurred chiefly in May, these measured between 4.5 and 16.5 mm, and had fed chiefly on Pseudocalanus. Larger whiting (between 21 and 52 mm) were taken in association with Rhizostoma. They were approximately 2–4 months old, and had fed on copepods supplemented with Hyperia and euphausiid furcilia. Immature whiting 77 mm long appeared in July in a shallow sandy bay—a nursery area. The fish were about 4–5 months old, and fed on swarming amphipods, isopods and mysids after dark, when these organisms were free-swimming. This diet was supplemented to an appreciable extent during the following April-June quarter by the inclusion of juvenile Ammodytes. After staying for nearly 1 year in the nursery area, the bulk of the fish appear to migrate to the open sea.In the open-sea habitat, the immature fish fed chiefly on euphausiids, decapods and sprats—nektonic forms particularly. These whiting are themselves eaten by larger whiting in the same habitat. Adult whiting (over 220 mm) were taken only offshore, and fed chiefly on euphausiids, Crangon, Pandalus, Pasiphaea, Clupea and gadoids. A few samples taken off the east coast of I.o.M. indicated that the whiting are capable of feeding on infauna and plankton in an environment deficient in active epifauna and nekton. The whiting is an active feeder throughout the year.Two length-weight relationships have been calculated for Manx whiting: nursery-area, and open-sea fish—the latter gain weight more rapidly than the former would be expected to do.
Studies on Marine Flagellates VII. Nephroselmis Gilva Sp.Nov. and Some Allied Forms
Authors: Parke M. , Rayns D. G. 
Published: May 2009

A new species provisionally attributed to the genus Nephroselmis has been described with the aid of light- and electron-microscopy. Significant features include the presence of a single layer of scales over the flagellar and cell surfaces as in Micromonas squamata Manton & Parke, though the morphology of the flagellar scales is as in the outer scale layer of Pyramimonas and Halosphaera. Reasons are given for rejection of Thalassomonas on the grounds of nomen confusum and for homologizing various representatives of it with Micromonas squamata.Some additional facts about the latter include details of the imbrication of the flagellar scales and demonstration, made possible by the use of lead staining of sections, of a close association between golgi bodies and the scale-producing vesicles.
Carbohydrate and Organic Matter in Suspension in Loch Striven during 1962
Authors: Marshall S. M. , Orr A. P. 
Published: May 2009

The number of diatoms, and the carbohydrate and organic matter in suspension, were followed during most of the year 1962 in Loch Striven.A rise in diatom numbers was always accompanied by a rise in both carbohydrate and organic matter, but the agreement was not quantitative.
Observations on the Fertility of the Oyster (Ostrea Edulis)
Authors: Walne P. R. 
Published: May 2009

The production of larvae by Ostrea edulis L. was studied in collections made from brooding females obtained from oyster grounds on the east, south and south-west coasts of England and from the Menai Straits. The size of the brood was directly related to the size of the oyster, but considerable variation was found from oysters of the same size whether measured as diameter, volume between the shells or dry meat weight. Part of the scatter was due to variation in condition of the oyster at spawning; oysters in good condition at the time of spawning produced more eggs than those in poor condition. This cause of variation was also seen in different populations; those with a high average condition index had a higher average fertility than those in poor condition, although the correlation was not quite significant at the P = 0.05 level (r = 0.632). It is presumed that most of the remaining variation is of genetic origin.Fertility was related to size rather than age, although it is suggested that in some old slow-growing oysters it may be reduced. No decline in fertility was found as the breeding season progressed, nor was there clear evidence that larvae are liberated at a smaller size late in the season.A comparison of the average size of broods at an early stage of development with those that were nearly mature showed that there was no loss of larvae during brooding. Samples of shelled larvae from 204 broods were measured; less than 10 % exceeded 190 µ size.
The Feeding of Plaice and Sand-Eel Larvae in the Southern North Sea
Authors: Ryland J. S. 
Published: May 2009

Larvae of the sand-eel,Ammodytes marinus, appear in large numbers in the Southern Bight during March, some 2–4 weeks after the peak hatching period of plaice eggs. The sand-eel larvae outnumber those of the plaice about tenfold, but the factor may be 60 or more locally.The principal food components in sand-eel guts in 1961 were copepod nauplii and appendicularians, while plaice were feeding almost exclusively on the latter. Larvae of both species show identical feeding patterns, with activity ceasing at night, and both aggregate during the day at depths of about 2–6 fm. Thus the sand-eel larvae are not separated from the plaice larvae by any pattern of behaviour, and are partially exploiting the same food reserve.Consideration of prey size suggests that any direct competition from the larval sand-eels would first affect the smallest plaice larvae, which are in any case the most vulnerable to shortage of food. But any reduction in the crop of small appendicularians will later be reflected in the number of larger ones, and in this way older plaice larvae might be affected. While the food supply appears to have been adequate up to the time of the investigation, the reserve apparently represented only 3 days' rations. The significance of this observation is unfortunately obscured by our ignorance of appendicularian biology; but, should the food reserve become so diminished, competition between plaice and sand-eel larvae might be expected. The extent of its impact on survival is only likely to emerge from more comprehensive surveys.
The ecology of Chondrus crispus and Gigartina stellata (Rhodophyta) in Galway Bay
Authors: Pybus C. 
Published: May 2009

In the Galway Bay area the carragheen species, Chondrus crispus Stackh. and Gigartina stellata (Stackh.) Batt., are still collected using traditional methods. The weeds are picked by hand, spread out on any convenient area of grass, allowed to dry and, in the case of Chondrus, bleach in the open air. Most collecting is done during the autumnal equinoctial spring tides and is virtually restricted to the intertidal zone.The Irish seaweed industry has declined since 1960, when according to Chapman (1970) production reached its peak. When describing the industry in 1974, Cahill & Sweeney made the following comments. ‘A small number of firms are engaged in harvesting and primary processing. Between 1000 and 1250 people are seasonally employed. Almost 40000 tons of wet weed are harvested annually with a landed value of approximately £200000. Harvesting techniques are largely manual and there is a possibility that the industry may decline in the medium term as alternative and more lucrative employment opportunities become available.’