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Analysis of a Lake Superior coastal food web with stable isotope techniques Analysis of a Lake Superior coastal food web with stable isotope techniques

Food-web components of a Lake Superior coastal wetland and adjacent offshore waters were examined with stable isotope ratio techniques for carbon and nitrogen. We found distinct carbon isotope ratio signatures for organisms collected in the wetland and from offshore. Both food-web groups seemed to be based on carbon fixed by phytoplankton. Compared to offshore organisms, the wetland food...
Authors
Janet R. Keough, Michael E. Sierszen, Cynthia Hagley

Ecosystem management: A decision support GIS approach Ecosystem management: A decision support GIS approach

This paper describes a new approach using decision support GIS for handling information in ecosystem management. Technical research efforts resulted in specialized spatial decision support systems for wetland restoration planning, wetland permit analysis, and wildlife research and management. These applications are briefly presented to illustrate the usage of the methodology. With its...
Authors
Wei Ji

Lipid and water depletion in migrating passerines following passage over the Gulf of Mexico Lipid and water depletion in migrating passerines following passage over the Gulf of Mexico

Lipid depletion is currently believed to be the primary factor limiting flight duration of migrating birds in North America, while the influence of water loss is thought to be small. Three migrating species of passerines, wood thrush (Hylocichla mustelina), Swainson's thrush (Catharus ustulatus), and summer tanager (Piranga rubra) were captured during the 1993 spring migration just after...
Authors
P.L. Leberg, T. J. Spengler, Wylie C. Barrow

Food availability and feeding preferences of breeding fulvous whistling-ducks in Louisiana ricefields Food availability and feeding preferences of breeding fulvous whistling-ducks in Louisiana ricefields

Expansion of the breeding distribution of the Fulvous whistling-duck (Dendrocygna bicolor) into the southeastern United States after the mid-1800s coincided with the establishment of rice (Oryza sativa) cultures in Texas, Louisiana, and Florida. In southern Louisiana, where approximately 80% of rice is aerially seeded in water, Fulvous whistling-ducks are suspected of feeding extensively...
Authors
William L. Hohman, Timothy M. Stark, Joseph L. Moore

Biomass patterns in seagrass meadows of the Laguna Madre, Texas Biomass patterns in seagrass meadows of the Laguna Madre, Texas

The Laguna Madre of Texas supports the most extensive seagrass meadows in the western Gulf of Mexico, In 1988 seagrasses covered 730 km2 or about three-quarters of the embayment. Halodule wrightii dominated the entire upper laguna, and total biomass was quite uniform near 160 g˙m-2 throughout. Four species shared dominance in the lower laguna. Where present mean biomass of Thalassia...
Authors
Christopher P. Onuf

A 7 year record of above-ground net primary production in a southeastern Mexican mangrove forest A 7 year record of above-ground net primary production in a southeastern Mexican mangrove forest

Spatial and temporal variations in net above-ground primary production (NPP) and litter turnover rate were studied, from 1987 to 1993, in a mangrove forest bordering Laguna de Terminos, Mexico. NPP, the sum of total litter fall and wood production, was measured over the entire study period in three zones in a basin forest: zone I, where Rhizophora mangle (red mangrove) occurs but...
Authors
J.W. Day, Carlos Coronado-Molina, F. R. Vera-Herrera, R. Twilley, V. H. Rivera-Monroy, V. H. Alvarez-Guillen, Richard H. Day, William Conner

Age determination in manatees using growth-layer-group counts in bone Age determination in manatees using growth-layer-group counts in bone

Growth layers were observed in histological preparations of bones of known-age, known minimum-age, and tetracycline-marked free-ranging and captive Florida manatees (Trichechus manatus latirostris), substantiating earlier preliminary findings of other studies. Detailed analysis of 17 new case histories showed that growth-layer group (GLG) counts in the periotic bone were consistent with...
Authors
M. Marmontel, T. J. O'Shea, H. I. Kochman, S.R. Humphrey

Environmental gradients and identification of wetlands in north-central Florida Environmental gradients and identification of wetlands in north-central Florida

Vegetation composition, soil morphology, and hydrology were characterized along wetland-to-upland gradients at six forested sites in north-central Florida to compare results of Federal wetland delineation methods with 3–5 yr of hydrologic data. Wetland and non-wetland identifications were supported by hydrology data in eight of nine plant communities. Lack of hydric soil indicators and...
Authors
M.M. Davis, S.W. Sprecher, J.S. Wakeley, G.R. Best
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