Cholecalciferol-induced bait shyness in possums (Trichosurus vulpecula)

Cholecalciferol (vitamin D₃) is used in a variety of bait formulations to control populations of the brushtail possum (Trichosurus vulpecula), an introduced pest that seriously damages and threatens primary production and native biota in New Zealand. In cage trials, possums readily ate sublethal baits containing either an estimated LD₁₅ or LD₄₀ dose of cholecalciferol, leading to a depression of appetite that lasted for 7-15 days. When lethal quantities of baits were presented 21-30 days after the initial LD₁₅ or LD₄₀ baits, 40 and 88% of possums survived, respectively, compared with a 21% survival rate among naive possums, and bait consumption was also reduced among survivors of the initial baits. Subsequent switching of the bait base to a gel was partially successful in overcoming bait shyness, killing 40% of one group (formed by pooling the original groups), while switching both the bait type (to gel) and the toxicant (to 1080) resulted in a 63% mortality rate in a second group. By comparison, 95 and 100% of naive groups were killed by cholecalciferol and 1080 gel respectively. Practical measures are identified for both avoiding and overcoming bait shyness based on the use of alternative bait types and toxicants.     

Lactate dehydrogenase isoenzymes in the lungs of sheep with acute and chronic pneumonia

Total lactate dehydrogenase and the absolute and percentage levels of its isoenzymes were measured in lung lesions and macroscopically normal areas of lung from lambs with chronic proliferative exudative pneumonia and acute pasteurella pneumonia. Lung lesions had a higher total enzyme activity which was associated mainly with increases in the activity of the LDH4 and LDH5 isoenzymes, particularly in chronic pneumonia, and gave lung lesions a considerable potential for altering the serum isoenzyme distribution. Thus, the nature of any changes in the serum isoenzyme distribution will depend on whether the isoenzymes are released from abnormal or normal areas of lung. This appears to be the first report on lactate dehydrogenase isoenzymes in ovine pneumonia.     

An improved TLC method for the detection of flunixin in equine serum

A method for flunixin detection in equine serum extracts involving thin layer chromatography, spraying the chromatogram with alkaline sodium hypochlorite solution and heating with a detection limit of 50 ng ml-1 is described.     

Analysis of peritoneal fluid as a diagnostic aid in grass sickness (equine dysautonomia)

The analysis of peritoneal fluid is of value in the differential diagnosis of equine colic but its characteristics have not been evaluated in grass sickness. Peritoneal fluid was collected from 15 normal horses and from 11 cases of medical colic, 11 cases of surgical colic, 20 cases of acute grass sickness and 13 cases of subacute grass sickness. The fluid was analysed for its appearance, total and differential white cell count, specific gravity, total protein concentration and total and intestinal alkaline phosphatase activity. Fluid from cases of medical colic was normal in these respects. Surgical cases were unique in having bloodstained fluid with a high alkaline phosphatase activity. Grass sickness cases had a higher specific gravity and protein content than the cases of medical colic although the appearance of the fluid was similar. Grass sickness cases were distinguishable from cases of surgical colic on the basis of the appearance of the fluid and its lower alkaline phosphatase activity.     

Indices of landscape pattern

Landscape ecology deals with the patterning of ecosystems in space. Methods are needed to quantify aspects of spatial pattern that can be correlated with ecological processes. The present paper develops three indices of pattern derived from information theory and fractal geometry. Using digitized maps, the indices are calculated for 94 quadrangles covering most of the eastern United States. The indices are shown to be reasonably independent of each other and to capture major features of landscape pattern. One of the indices, the fractal dimension, is shown to be correlated with the degree of human manipulation of the landscape.     

Scaling relations between riparian vegetation and stream order in the Whitewater River network,Kansas, USA

Riparian communities have been well-studied along individual streams, but not within the context of networks of which streams are a part. To study networks, hydrologists use Horton–Strahler ordering to assign streams to discrete categories in which increasing numerical value (ω) reflects increasing size of the stream and complexity of the network. A key use of this classification method has been to demonstrate scaling relations between hydrogeomorphic variables and order. These relations now provide a foundation to determine how ecological processes are associated with the geometry and topology of river networks. We used geographic information systems (GIS) to map and measure the stream network and riparian vegetation of the Whitewater River basin of eastern Kansas, USA. With the resulting data, we tested if (1) riparian vegetation scaled with order, and (2) riparian vegetation at confluences of two streams differed from that found along constituent streams. Most characteristics of riparian vegetation scaled with order. In confluence zones, density and diversity of riparian vegetation generally were equivalent to that of the largest constituent stream. Scaling relations between riparian vegetation and order provide a framework to quantify the role of riparian vegetation in the water balance of stream networks and a tool to predict area and distribution of riparian vegetation from network topology.