Recoveries by hunters of 842 black swans banded at Lake Whangape, North Island, New Zealand,between 1962 and 1975 were mainly confined to the Waikato and Northland districts, 88% being recovered within a 30-mile (50 km) radius of the lake. Five were recovered from South Island. At Lake Ellesmere, South Island, a cyclonic storm in April 1968 which altered the lake's ecology caused a change in the swans' dispersion.
During 1956-68 and 1969-75 respectively, hunters returned 3950 and 745 bands, 83 and 78% of which were from within 10 miles (16km) of the lake. Of the more distant recoveries, 72 and 73 % were from the south-east of South Island. Most of the swans recovered from North Island were 2-year-olds.
In 1969-75 more first and second-year birds and fewer older birds were shot on Lake Ellesmere than during 1956 and 1968. This difference is considered the result of a shorter game season and poorer food supply at the lake in 1969-75.
BRIDGES is a recurring feature of J-NABS intended to provide a forum for the interchange of ideas and information between basic and applied researchers in benthic science. Articles in this series will focus on topical research areas and linkages between basic and applied aspects of research, monitoring, policy, and education. Readers with ideas for topics should contact Associate Editors Nick Aumen and Ashley Moerke.
Karst aquifers are important groundwater resources, but are vulnerable to contamination due to relatively rapid subsurface transport. Springs, points where the landscape and water table intersect and cold groundwater discharges, link aquifer systems with land surfaces and water bodies. As such, in many regions, they are critical to the viability of lakes, streams and cold-water fish communities. An understanding of where springs are located is important to watershed, fishery and environmental management efforts in karst regions. To better understand spatial distribution of springs and as a potential method for identifying variables that characterize locations of springs for improved land and watershed management, a nearest-neighbor analysis and a discriminant function analysis (DFA) of springs were conducted in Winona County, Minnesota, USA, a karst landscape. Nearestneighbor analysis examined the spatial spring distribution. Twenty-two variables describing the locations of springs were analyzed to ascertain their ability to discriminate correct aquifer unit or bedrock unit classification for each spring. Springs were clumped with the highest densities in the lowest elevations. Springs were correctly assigned to aquifer units and bedrock units with eight and 11 landscape variables, respectively. Forest land cover was the only land cover type contributing to spring discrimination. Consideration of upland human activities, particularly in forested areas, on spring discharge along with a better understanding of characteristics describing spring locations could lead to better management activities that locate and protect springs and their important contributions to regional ecohydrology.
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