PARENT SESSION
Contributed Oral Session 139: Landscape Ecology: Streams; Wetlands
Thursday, August 11, 1:30 PM - 5:00 PM, Meeting Room 520 A, Level 5, Palais des congrès de Montréal
From the land to water: linking watershed land cover and estuarine condition.
DeLuca, William 1, Marra, Peter1, Baker, Matthew1, King, Ryan2, Weller, Donald1, 1 Smithsonian Environmental Research Center, Edgewater, MD, USA2 Baylor University, Waco, TX, USA
ABSTRACT- Approximately two thirds of the global population lives within 400 km of a coastline, consequently estuaries are becoming increasingly impacted by anthropogenic landscape modifications. We developed an index of waterbird community integrity (IWCI) and applied it to Chesapeake Bay, USA for two years (2002-2003) to examine the relationship between land cover and estuarine ecosystem integrity. We identified development as the primary land-cover stressor to estuarine integrity and tested its effect on IWCI scores at three different spatial scales. Our results indicate that models including land cover within the entire watershed while emphasizing development near the shoreline are most accurate when predicting IWCI scores. Changepoint analysis indicated that waterbird community integrity declined significantly when as little as 4% of the area near the subestuary shoreline was developed. Although the total effects of development on the waterbird community did not vary between years, direct effects accounted for 92% of this impact in 2002 (drought year) whereas in 2003 (wet year) 62% of the total effects were attributed to indirect pathways. Such findings suggest that urban development in the coastal zone may have more variable and more profound impacts than previously considered.
Key words: index of waterbird community integrity, landscape modifications, threshold response, direct and indirect effects