Lago Rupanco is located in the central plain of Chile
(Borgel, 1964) at 40° 50' S; 72° 30' W. It lies at 117 m
above sea level, and corresponds to type 28c of Hutchinson's
(1967) classification. Lago Rupanco is a warm, monomictic
lake, with winter circulation and summer stratification.
Physical,...
Total copper concentrations of 10 [mu]g/l to 100 [mu]g/l appeared to
alter the predator-prey interactions of fathead minnows (Pimephales
promelas) and Daphnia pulex. The effect of copper concentration on
the total amounts of D. pulex consumed over a 12-h period varied with
the density of prey stocked hourly in the...
From July 1985 to April 1987 the pelagic zooplankton community of Crater Lake, Oregon was studied to determine taxonomic structure, absolute and relative densities, and spatial and temporal distributional patterns. Samples were collected using vertically-towed zooplankton nets. The community structure consisted of two cladoceran and nine rotifer species, which were...
A vegetation study was made of four coastal marshes near Juneau,
Alaska. Results confirmed earlier studies' findings in southeast
Alaska that communities or assemblages of species can be identified
but from marsh to marsh these assemblages appear to have no consistent
relationship to each other or to environmental "factors" such...
Seasonal abundance and life history traits were compared between populations of the brine fly Ephydra (Hydrokyrus) hians Say (Diptera:Ephydridae), from two western Great Basin alkaline salt lakes. Abert Lake, Oregon, has a relatively low salinity (20-30 g/1 total dissolved solids) and more co-inhabitant benthic species than the higher salinity Mono...
Larval mortality of leafcutting bee, Megachile pacifica (Panzer)
(= rotundata (F.)), is high, usually exceeding 50%. Parasites and
predators are not a limiting factor in the survival of the progeny.
The disease chalk brood has been an important mortality factor since
1974. Inadequate food supply, pollen and nectar, may affect...
National Forest management in the Pacific Northwest is shifting
from a focus on commodity production to ecosystem management, in which
the health of the entire forest ecosystem is considered, rather than that
of a few key species. Ecosystem management includes retention of some
live trees following timber harvest (green-tree retention)...
The groundfish trawl fishery operating off the coasts of Oregon
and Washington 1985-1987 caught six major assemblages of species
which could be treated as units in developing mixed-species
management plans. Eighty-one percent of the tows observed on
commercial vessels were consistently placed in one of the assemblage
designations using three...
