ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1977.tb04566.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Since 1971, four peregrine falcons,Falco peregrinus,coated with an oil‐like contamination, have been received for analysis at Monks Wood Experimental Station. All were from north or west Scotland. The contamination from one bird was examined and found to be a highly weathered oil of recent biological origin. The biochemical evidence did not indicate an unequivocal source for the oil, but was compatible with the hypothesis, for which there is strong circumstantial evidence, of fouling by stomach oil from a fulmar,Fulmarus glacialis.The possible circumstances of the oiling are discussed. Stomach oil production by petrels and albatrosses is unlikely to have evolved solely in response to selection pressure for nest defence. Oiling by fulmars appears to a small, but possibly significant, cause of mortality in coastal peregrine

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1977.tb04567.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Various aspects of the biology, population dynamics, growth, sexuality, reproduction, settlement and mortality of populations ofCorbicula fluminea(Muller, 1774) inhabiting Plover Cove reservoir and the Shum Chuen river, Hong Kong are described. These data are correlated with the hydrological picture of the reservoir to obtain a better understanding of the conditions under which the processes of growth, reproduction and settlement occur. An analysis of the shell dimensions of the component age groups comprising the population is obtained and, using the growth formula of Bertalanffy (1938), the maximum theoretical length ofC. flumineafor this locality is calculated, which when considered in conjunction with other data relevant to the biology provides a more meaningful definition of this species. Such information, if obtained for other species, would provide a better taxonomic picture of the Corbiculacea as a whole and permit a greater understanding of those corbiculids introduced into the U.S.A. which are a pest of water supply systems. A preliminary comparison with such information as is available from the North American populations ofCorbicula,indicates that at least two species, namely C.fluminea(Muller 1774) andC. fluminalis(Muller 1774) have been possibly introduced.Other species may have been introduced, but until a more thorough examination of the species both within their home and introduced ranges has been undertaken, the taxonomic picture will remain obscure.This paper demonstrates that in Hong KongC. flumineais a protandric consecutive hermaphrodite, which incubates its young in a ctenidial marsupium. This refutes the conclusion reached by earlier researchers and emphasizes the need for more detailed studies.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1977.tb04568.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Three races ofQuelea quelea,inhabiting East, West and southern Africa, each perform a migration at the beginning of the wet‐season, but the distances involved differ greatly. The quantity of pre‐migratory fat accumulated differs in the three populations and correlates with the respective migration lengths. The timing of fattening is in some way associated with the onset of heavy rain. Though winged termites usually provide the food supply for fattening they do not appear to stimulate the process. Flight muscle hypertrophy accompanies fattening; it is suggested that the extra protein is required for body maintenance during the fasting period of the migrat

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1977.tb04569.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

The seasonal testicular changes in the Soft‐shelled turtle,T. sinensis,show a well‐marked temporal differentiation between the functional activity of the seminiferous tubules and the interstitial tissue. In the March‐April breeding period, the interstitial cells are large and lipid‐free, with rounded turgid nuclei and a strongly positive reaction to tests for A5‐3P‐hydroxysteroid dehydrogenase. As might be expected with such histochemical manifestations of high androgen secretory activity, the epididymis is also highly developed during this period. In contrast, the seminiferous tubules are regressed, spermatogenetically inactive, and heavily lipoidal. Fertilization is achieved by spermatozoa discharged from the epididymidal canals.Immediately following the breeding period, the interstitial tissue atrophies and becomes strongly lipoidal and negative to tests for 3P‐HSD. This interstitial regression is accompanied by the regression of the epididymides and a concomitant recrudescence of seminiferous tubule activity. The latter rapidly become depleted of their lipid and become strongly positive to tests for 3P‐HSD. Spermatogenesis resumes, and the seminiferous tubules become filled with representatives of all the germinal stages by the end of May. In early autumn there is a cessation of spermatogenesis, and, as the epididymides recover under the influence of a recovering androgen secretion by the redeveloping interstitial cells, the spermatozoa become evacuated from the tubule‐lumina to the epididymidal canals, where they remain until the succeeding breeding season.The seasonal histochemical events are discussed in relation to the basic pituitary‐gonadal regulation of

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1977.tb04570.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

The major blood vessels of the sealion pupsNeophoca cinereaandPhocarctos hookeriare described, and the results compared with descriptions in the literature of the vascular systems of phocoid and otarioid seals. The arteries of pinnipeds, in general, follow the normal mammalian plan, but modifications have occurred in the venous system. These modifications have been well documented for many phocids, but in the eared seals and walruses limited information suggests differences from the phocid pattern. Eared seals and walruses have a venous system much more like that of a typical mammal and they do not appear to have pericardial rete, or a typical phocid renal stellate plexus, or enlarged extradural vein; while they do possess normal renal veins and venous drainage of the head by the external jugular vein.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1977.tb04571.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

The invertebrate fauna of mud bottoms in Lake George was examined in 1971‐1972. No evidence was found of seasonal changes in the composition or absolute levels of the benthic invertebrate density and biomass, though local changes occurred in some species which were attributed to swarming behaviour or larval settlement patterns. Comparison of the benthic fauna at nine sites showed considerable similarity over the whole lake. Multivariate analysis on the sample data showed that an “inshore/offshore” difference accounted for 30‐40% of the total variation between samples. It is suggested that this difference is related to the texture and stability of the substratum. Comparison with the literature shows that the Lake George benthos is an extreme type, but one that is represented in other inter‐tropical Afri

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1977.tb04572.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

The lengths, weights and condition factors of young adult lampreys caught feeding on Gaspereau,Alosa pseudoharengus.Shad,Alosa sapidissima,and White suckers,Catostomus commersoni,in the lake‐like extensions of the St. John River system during May, suggest that many lampreys do not feed in the nine to ten months following the initiation of metamorphosis in mid‐July. The mean lengths (d‐95% confidence limits) of individuals taken in four samples between May 13 and 29 did not differ significantly and ranged from 132‐7± 2‐81 to 135‐7 ±3‐71 mm. A significant increase in mean condition factor from II15 to 1‐353 during this time indicates that the short period spent feeding in May enables the animal to replenish its food reserves prior to its downstream migration. Since several of the 81 feeding adults caught between the latter part of June and mid‐July, at a point 140 km from the estuary of the St. John, were still attached to spawning‐run Atlantic salmon,Salmo salar,this teleost host had probably been responsible for their transport upstream. The wide range in their length (156‐403 mm), together with the presence in the lakes in May of a few young adults larger than those which have only just started feeding, suggest that the time of onset of the parasitic phase is variable but may generally commence in either the late autumn or in the spring. Scarring on salmon due to lamprey attack was predominantly (84%) on the ventral surface between the operculum and caudal peduncle. Over 35 % of the salmon examined in June 1975 had been attacked, more of these attacks being on the right side of the body of both males (59‐6%) and females (49‐8%) than on either the left (20‐2 and 23‐7 %) or both sides (20‐2 and 26‐5 %). While lamprey attacks may cause some mortality among the smaller teleosts, any effect on salmon is probably indirect through causing increased susceptibility to infection and stress. The ability of adult anadromous Sea lampreys to feed and grow in fresh water demonstrates the relative ease with which landlocked forms could have been evolved in response to extreme environmental changes. This evolutionary step has involved a decline in the ability to osmoregulate in high salinities and a reduction in body size and fecundity, the adaptive significances of which are discussed. Data on upstream migrants indicate that males and females undergo length reductions of at least 11 and 15 % respectively between the time of their entry into fresh w

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1977.tb04573.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY