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Filter Total Items: 3377

Geographic variation in Yellow-headed Blackbirds from the northern Great Plains

We assessed geographic variability in morphology among Yellow-headed Blackbirds (Xanthocephalus xanthocephalus) collected from breeding populations in Minnesota, North Dakota, and South Dakota in the United States and Alberta, Manitoba, and Saskatchewan in Canada during spring. Both male and female Yellow-headed Blackbirds tended to be larger in the more northern breeding populations. Males collec
Authors
Daniel J. Twedt, William J. Bleier, George M. Linz

Hydrologic control of litter decomposition in seasonally flooded prairie marshes

The effect of seasonal inundation on the decomposition of emergent macrophyte litter (Scolochloa festucacea) was examined under experimental flooding regimes in a northern prairie marsh. Stem and leaf litter was subjected to six aboveground inundation treatments (ranging from never flooded to flooded April through October) and two belowground treatments (nonflooded and flooded April to August). Fl
Authors
Hilary A. Neckles, Christopher Neill

Community‐level field method for testing the toxicity of contaminated sediments in estuaries

The objective of this study was to demonstrate a method for testing the toxicity of contaminated sediments under field conditions. An artificial sediment that matches field sediment in grain‐size distribution and organic matter content was mixed from 11 components and used as the test substrate. Clean sediments and sediments spiked with zinc (∼8,000 mg/kg) were exposed in the field on a holding ra
Authors
Mary C. Watzin, Pasquale F. Roscigno, W. David Burke

Distribution and status of submerged vegetation in estuaries of the upper Texas coast

Composition and biomass of beds of submerged aquatic vegetation (SAV) in estuaries along the upper Texas coast were examined from bottom core and rake samples taken along 72 line transects during July–August 1987. Substrate composition, salinity, water depth, and water clarity were also measured at each sample station. Halodule wrightii was the dominant species of SAV meadows (69% occurrence), fol
Authors
S.E. Adair, J.L. Moore, Christopher P. Onuf

Aquatic invertebrate production in southeastern USA wetlands during winter and spring

We measured aquatic invertebrate abundance, standing stock biomass, and community production in three types of wetlands on Noxubee National Wildlife Refuge from December 1987 through April 1988. Together, Orthocyclops modestus and Daphnia pulex were the most abundant organisms collected in all habitats during both winter and spring, but each contributed little to total standing stock biomass or pr
Authors
Walter G. Duffy, Douglas LaBar

MAPS is for the birds

No abstract available
Authors
David L. Watts, Daniel J. Twedt, Allan J. Mueller

Effects of weather and tides on feeding and flock positions of wintering redheads in the Chandeleur Sound, Louisiana

We studied the effects of weather and tides on percent feeding and flock positions of wintering redheads (Aythya americana Eyton) in the Chandeleur Sound, Louisiana, USA. Flock scans (n = 750) were made on 55 flocks from November through March of 1988–1989. The percent of the flock that was feeding was negatively correlated with time of day, temperature, water level, and distance of the flock from
Authors
Thomas C. Michot, E. Barry Moser, Wayne Norling

Mangroves, hurricanes, and lightning strikes: Assessment of Hurricane Andrew suggests an interaction across two differing scales of disturbance

The track of Hurricane Andrew carried it across one of the most extensive mangrove for ests in the New World. Although it is well known that hurricanes affect mangrove forests, surprisingly little quantitative information exists concerning hurricane impact on forest structure, succession, species composition, and dynamics of mangrove-dependent fauna or on rates of eco-system recovery (see Craighea
Authors
Thomas J. Smith, Michael B. Robblee, Harold R. Wanless, Thomas W. Doyle