HR: 16:30h
AN: NB44C-05    [Abstracts]
TI: Relationships Between Litter Processing and Impervious Surface Cover in Headwater Tributaries of the St. Johns River, Florida
AU: * Chadwick, M A
EM: chadwick@bama.ua.edu
AF: Department of Biological Sciences, University of Alabama, Box 870206, Tuscaloosa, Al 35487 United States
AU: Dobberfuhl, D R
EM: ddobberfuhl@sjrwmd.com
AF: Division of Environmental Sciences, Saint Johns River Water Management District, 4049 Reid St. , Palatka, Fl 32177 United States
AU: Benke, A C
EM: abenke@biology.as.ua.edu
AF: Department of Biological Sciences, University of Alabama, Box 870206, Tuscaloosa, Al 35487 United States
AU: Huryn, A D
EM: huryn@bama.ua.edu
AF: Department of Biological Sciences, University of Alabama, Box 870206, Tuscaloosa, Al 35487 United States
AU: Suberkropp, K
EM: ksuberkp@biology.as.ua.edu
AF: Department of Biological Sciences, University of Alabama, Box 870206, Tuscaloosa, Al 35487 United States
AU: Thiele, J E
EM: thiel002@bama.ua.edu
AF: Department of Biological Sciences, University of Alabama, Box 870206, Tuscaloosa, Al 35487 United States
AB: We investigated relationships between land-use and litter processing in 18 tributaries of the St. Johns River, Florida. The percent total impervious area (PTIA) of these catchments ranged from 0-66%. We measured mass loss and fungal biomass (as ergosterol) and associated macroinvertebrate biomass for 2 litter species (red maple [Acer rubrum] and sweetgum [Liquidambar styraciflua]). Processing rates ranged from 0.010-0.046d^-1 for maple and 0.006-0.018d^-1 for sweetgum. The fastest processing occurred at intermediate PTIA. Fungal biomass peaked at 24 days with the lowest biomass occurring in the low PTIA stream. Rates of processing were positively related to both mean macroinvertebrate biomass and taxa richness. Shredder biomass was not related to maple, but was negatively related to sweetgum processing. Scraper biomass peaked at intermediate PTIA, and was positively related to processing rates for both leaf species. We reduced correlated physicochemical, land-use and biological variables to several orthogonal variables using principle components analysis. Regression models based on these variables accounted for 70% of the variance in processing rates for both leaf species. Collectively, these results demonstrate that PTIA and other land-use indicators are associated with differences in stream ecosystem patterns and processes between low gradient, subtropical streams.
DE: 9810 New fields (not classifiable under other headings)
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly