A modified photogrammetric technique for assessing age-structures of elephant populations and its use in Kidepo National Park

(1) A modification of an aerial photographic technique for assessing the age-structure of African elephant populations is introduced. (2) The method is quick, inexpensive, and provides important population dynamics information relevant to one of the most serious wildlife management problems in Africa–namely, the interaction of elephants and their habitats. (3) The method consists of photographing elephant breeding herd groups vertically, measuring their relative lengths, and then relating the lengths to a mean breeding herd growth-curve. (4) An example of the application of the technique is given in an assessment of the age-structure of two elephant populations in the Kidepo Valley National Park, Uganda. (5) The Kidepo populations are similar in age-structure and are in general healthy. The similarities probably represent allopatric responses to the same climatic regime. (6) Peaks and troughs in the age-structures are related to local rainfall, which indirectly aifects conception and mortality of young animals. (7) There are some obvious differences between the two populations, the home-ranges of which exhibit differences in rainfall and habitat characteristics. The differences between the populations reaffirm the sensitivity of elephant population regulating mechanisms to local variations in climate and rainfall. (8) The relative roles of post-mortem and observational techniques in elephant studies and the need for long-term research are discussed.     

Photosynthetic and Respiratory Studies During Pod and Seed Development in Pisum sativum L.

The photosynthetic and respiratory potential of Pisum sativumfruit depends on a combination of factors such as fruit age,light intensity and the atmospheric CO₂ concentration. Fruitwere capable of a net CO₂ uptake from the atmosphere only duringthe period of pod extension growth and at light intensitiesgreater than 12 klx. During subsequent development the respiratoryCO₂ evolution attributable to seed growth exceeded the photosyntheticcapacity of the pod. Despite this the extent of fruit CO₂ losswas consistently less in the light than in the dark. An increase in the CO₂ concentration beyond 300 p.p.m. markedlyreduced fruit CO₂ loss and in some instances effected a transitionfrom a net CO₂ output to a net CO₂ uptake. Conversely, a decreasein the CO₂ concentration substantially increased the extentof fruit CO₂ loss. The CO₂ compensation point concentrationincreased with fruit age from 150 p.p.m. to possibly more than550 p.p.m., whereas the corresponding value for the pod (minusseed) remained between 120 and 175 p.p.m. throughout fruit development. A proportion of the CO₂ respired by the seed and pod accumulatedwithin the pod cavity. The CO₂ concentration attained dependedon fruit age and nodal location. In the course of fruit developmentconcentrations within the range 0•1 to 4{dot}3 per centCO₂ occurred during mid-photoperiod. The CO₂ concentration washighest when the enclosed seed had attained approximately 50per cent of their final dry weight.     

Observations on Pre-enrichment for Isolating Salmonellas from Sewage Polluted Natural Water Using Muller-Kauffmann Tetrathionate Broth Prepared with Fresh and Desiccated Ox Bile

Desiccated bile (Oxoid L50) was substituted for fresh bile obtained from the abattoir in Muller-Kauffmann Tetrathionate Broth. Two versions of the enrichment medium were prepared, one with desiccated bile the other with fresh bile. The efficiency of these two media was compared using 25 ml quantities of sewage polluted natural water as inocula. Direct enrichment and preenrichment techniques were used. With direct enrichment the Muller-Kauffmann Tetrathionate Broth prepared from fresh bile was more efficient for salmonella isolation. With the pre-enrichment technique using preliminary culture of the water sample in buffered peptone water prior to enrichment, there was no significant difference between the efficiency of the two versions of tetrathionate. Comparison of direct enrichment with the pre-enrichment method for isolating salmonellas from sewage polluted water clearly demonstrated the advantages of pre-enrichment. This would certainly have a bearing on the quantitative estimation of salmonellas in polluted water and might increase the number of serotypes isolated from a sample divided into subsamples.