Federally listed as threatened in 1990 primarily because of habitat loss, the northern spotted owl (Strix occidentalis caurina) has continued to decline despite conservation efforts resulting in forested habitat being reserved throughout its range. Recently, there is growing evidence the congeneric invasive barred owl (Strix varia) may be responsible for...
Dams impound the majority of rivers and provide important societal benefits, especially daily water releases that enable on-peak hydroelectricity generation. Such “hydropeaking” is common worldwide, but its downstream impacts remain unclear. We evaluated the response of aquatic insects, a cornerstone of river food webs, to hydropeaking using a life history–hydrodynamic...
The spatial distribution of plankton is highly aggregated, so one might expect that a vertically migrating animal enters a biotic environment that is markedly different each evening and that the changes in environment between daylight periods spent at depth are equally great. To measure the extent of these changes, as...
Estimates of species' vital rates and an understanding of the factors affecting those parameters over time and space can provide crucial information for management and conservation. We used mark–recapture, reproductive output, and territory occupancy data collected during 1985–2013 to evaluate population processes of Northern Spotted Owls (Strix occidentalis caurina) in...
Stratified bongo net samples taken at depths between 0 and 500 m at Ocean Station “P” in the subarctic Pacific in early July 1971 have been analyzed to determine the vertical structure of the zooplankton community. Distributions for 99 categories of animals have been grouped by factor analysis into five...
Population dynamics of Calanus finmarchicus have been modelled using very finely divided representation of the stock according to age-within-stage, in the manner of models developed by C. S. Davis, A. Sciandra, F. Carlotti and others. A key assumption of the model is that development
rate is relatively insensitive to food-limitation,...
An attempt has been made to interbreed populations of Acartia clausi from Woods Hole, Massachusetts, and Yaquina Bay, Oregon. Individuals from these populations are morphologically similar, but differ somewhat in size. Cultures from both sources produced many successive generations in the laboratory, but interbreeding with production of viable offspring did...
Many hazelnut (Corylus avellana L.) cultivars
fail to thrive in vitro on standard growth medium and the
reasons for poor growth are not well understood. Our initial
study of five C. avellana cultivars showed that changes in
the mineral nutrients of Driver and Kuniyuki walnut
(DKW) medium, including doubling the...
Calanoid copepod eggs have a robust, chitinous outer chorion, which makes field‐collected, formaldehydefixed eggs difficult to penetrate with stains or molecular probes. Egg development studies in copepods have involved physical, chemical, and enzymatic treatments to remove the chorion. We present an efficient, one‐step method for staining copepod eggs with the...