Browsing by Author "Day, J H"
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- ItemOpen AccessBehaviour of large mammals during the formation of Lake Kariba(1965) Child, Graham Foster Tamplin; Day, J HThe present study sought to make use of conditions during the formation of Lake Kariba, which resulted from the impoundment of the Zambezi. Three important factors led to changes in the ecology of the Kariba Basin, an area of 2,109 sq. miles, inhabited by primitive tribesmen and supporting extensive populations of large game mammals. In chronological order these were: i) the evacuation of the native inhabitants; ii) the preparation of fishing grounds; and iii) the inundation of almost the whole floor of the Central Zambezi Valley. The removal of the people resulted in large areas, especially those on or adjacent to fertile alluvium, which had been over-populated, being fallow until either cleared for fishing or submerged by the lake. The bush clearing of selected areas designated for fishing-grounds resulted in the destruction of most vegetation, while the filling of the Lake transformed a terrestrial environment, bisected by a seasonally fluctuating river, into a large static body of water within four and a half years. The habitat thus eliminated was typical of dry marginal areas in Rhodesia, the remaining strongholds of large mammals in the territory. This paper aims at describing some of the effects of the formation of lake Kariba on large mammals and their response not only to flooding, but also to the over-populated conditions which arose on islands on which they became marooned. In so doing it is, however, necessary to touch on the influence of past human settlement on the distribution and abundance of large mammals and on the effects of the clearing of incipient fishing-grounds. It is also convenient to mention briefly some of the most obvious responses of other groups of animals, as they showed certain similarities with those of mammals.
- ItemOpen AccessThe ecology of Patella(1973) Branch, George M; Day, J HThe present thesis is aimed principally at the population dynamics and biological interactions of Patella species. Most of the work is based on all eleven of the South African species, although volume of work necessitated the omission of the less common species from parts of the work. The research has been centred around the juveniles and adults, although it is realised that larval biology is logically the next field which needs to be explored. The thesis is presented as a series of separate papers, the first in published form and the remainder in manuscript, and is concluded by a resume. A single supporting paper is also included. The entire thesis is based on original work by the candidate, except where acknowledged in the text. The more important conclusions are summarised at the end of each section.
- ItemOpen AccessFishes of the genus Lutianus off the East African coast and Part 2: Notes on the biology of the Lutjanids of the East African coast(1960) Talbot, Frank Hamilton; Day, J HWhile investigating the biology of the economically important members of the genus Lutianus on the East African coastline, difficulty was experienced with the identification and the nomenclature of the group using existing literature. It was essential that adequate descriptions of the species of the genus should be available before their biology could be investigated. Routine work of the East African Marine Fisheries Research Organization has produced over 1,000 specimens for study. The Organization's vessel, the M.V. "Research", has collected by handlines, multiple trolling lines, gill nets, deep lines and basket traps over the six hundred mile coastline of Kenya, Tanganyika and Zanzibar Protectorate, i.e. from Lat. l o 30" S. to 10° 30" S. This material forms the basis of the present paper. Underwater observations with and without a Seibe-Gorman aqualung down to seven fathoms have been made on a number of coral reefs. In this way some knowledge of the habits of certain species of the genus has been acquired, and some species rarely taken by normal fishing methods were discovered to be common. Specimens of these have been collected by spear guns. Where notes of habits of a species have been made they have been appended under the heading "Ecological note". Of the thirteen species of the genus found in the area, all (except the very small L. ehrenbergi) pass through the local markets and are considered good eating, and seven are important food fishes. Economically the genus ranks as one of the three most important groups of bottom Telcosts; the others being the Epinephelids and the genus Lethrinus.
- ItemOpen AccessRed Sea Polychaetes from the Gulf of Elat (Aqaba) : a contribution to the knowledge of the Polychaeta fauna and the environmental conditions which affects its distribution(1973) Gitay, Asher; Day, J HA study of 50 samples of Polychaeta mainly from a northern profile (0.5 - 550 m) and down to 800 m, reveals that the fauna is characterised by extremely small specimens and a great taxonomic divergence. Techniques of handling minute specimens are described, together with 21 new species, including three subspecies, six new genera and a new subgenus. The discovery of aberrant genera indicates a substantial endemism, the evolution of which is enabled by: (a) the narrow Straits of Tiran which separates the Gulf from the Red Sea proper; (b) the hydrographical factors causing vertical homogeneity of temperature, salinity and oxygen, as well as (c) a possible zone of convergence which isolates the Gulf's northern part to an as yet unknown degree. The pattern of family distribution and specimen frequencies confirms the existence of six successive benthic associations along an analysed sediment profile. The poor biomass of the fauna indicates that the Gulf has an overall low productivity, caused by the limited amount of fresh water run-off, low content of organic matter and small quantities of nutrients.
- ItemOpen AccessSome aspects of the biology of the tobacco beetle, Lasioderma serricorne (F), (Coleoptera : Anobiidae)(1951) Rayner, Vivienne Iris; Day, J H; Broekhuysen, G JSince about 1866 the "tobacco beetle," Lasioderma serricorne, has been recognized as a pest of considerable economic importance. In addition to cured tobacco, the larval stage attacks a great variety of other materials of both plant and animal origin. Much of the work done on the biology of this beetle is fragmentary and not precisely recorded. The present author has aimed at correlating as much of the available valid information as possible and supplementing it with original records. Further, most previous investigations have centred on control rather than bionomics. But a sound knowledge of bionomics is needed as a basis for an effective scheme or control. Therefore, as research had to be limited in some way, in this paper attention has been paid primarily to bionomics (with some relevant morphology). The section on control comprises only a few original observations, and this aspect offers a wide field for future research.
- ItemOpen AccessSome aspects of the life history and bionomics of the Fig moth, Ephestia cautella (Wlk.), and some comparisons with the mediterranean flour moth, E. kuhniella (Zell) and the tobacco moth, E. elutella (Hb.)(1951) Newman, Patricia Ann; Day, J H; Broekhuysen, G JIn this paper, the morphological differences among the three common species of Ephestia have been confirmed by the present author, so that they may be easily identified. The life history of E. cautella has also been worked out, as well as some aspects of the life history of E. elutelle. and E. kuhniella. These three species have been found to differ at certain points of their life histories. Finally, the results of other authors have been compared with the findings of the present author.
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- ItemOpen AccessThe chaetognatha community of the Agulhas Current: its structure and related properties(1965) Stone, James Herbert; Stone, James Herbert; Day, J HA study has been made of a select group of marine zooplankton - the Chaetognatha. The analysis was done from a community viewpoint, that is, an objective technique was used to identify related groups of the Chaetognatha and these groups were then correlated with the distribution, abundance and fecundity of the individual species and with the existing hydrographical conditions. Competitive relationships among the species for habitats and niches were also examined.
- ItemOpen AccessThe ecology of Patella(1973) Branch, George M; Day, J HThe present thesis is aimed principally at the population dynamics and biological interactions of Patella species. Most of the work is based on all eleven of the South African species, although volume of work necessitated the omission of the less common species from parts of the work. The research has been centred around the juveniles and adults, although it is realised that larval biology is logically the next field which needs to be explored. The thesis is presented as a series of separate papers, the first in published form and the remainder in manuscript, and is concluded by a resume. A single supporting paper is also included. The entire thesis is based on original work by the candidate, except where acknowledged in the text. The more important conclusions are summarised at the end of each section.
- ItemOpen AccessThe fossil Cercopithecoidea of South Africa(1955) Freedman, Leonard; Day, J H