Spatially restricted surveys over time for aquatic resources

Consideration of the natural characteristics of aquatic resources and avail able frame material has led to the development of new designs for surveying large-scale regions. This paper illustrates survey designs developed to me et the requirements for surveying various aquatic resources, including a fi nite, discrete population, such as lakes within one or more states; a conti nuous linear population within a bounded area, such as wadeable streams wit hin one or more states; and a continuous two-dimensional population within a bounded area, such as coastal waters associated with one or more states. We present a unified approach that addresses the differences of the aquatic resources assuming the availability of frame material, such as Geographic Information System (GIS) coverages of the boundary for coastal waters, stre am network, and lake locations from U.S. Environmental Protection Agency's River Reach File 3, derived from U.S. Geological Survey digital line graph data from 1:100,000 scale maps. The basic design methodology distributes th e sample over the spatial extent of the resource domain, and a panel struct ure can be used to extend the sample through time. Key features for the app roach are (1) utilizing survey theory for continuous populations within a b ounded area, (2) explicit control of the spatial dispersion of the sample, (3) variable spatial density, (4) nested subsampling, and (5) incorporating panel structures for sampling over time.