LANDSCAPE APPROACHES TO THE ANALYSIS OF AQUATIC ECOSYSTEMS

1. In the mid-1970s, Hynes (1975) wrote eloquently about the complex i nteractions between aquatic and terrestrial systems. Central theories in stream ecology developed thereafter have dealt with the longitudina l flow of energy, materials and organisms in streams, and, with the ex ception of the flood pulse concept (Junk, Bayley & Sparks, 1989), have largely ignored areas outside the riparian zone. The structure of the upland and activities occurring there play a more important part than previously recognized in regulating community structure and ecosystem processes in streams. 2. These new perspectives are made possible by developments in hierarchy theory, patch dynamics, and the refinement o f tools used to quantify spatial and temporal heterogeneity. 3. Geogra phical information systems (GIS), image processing technology and spat ial statistical techniques allow quantitative assessment of lateral, l ongitudinal and vertical components of the landscape that interact at several spatial and temporal scales to influence streams. When GIS is used in concert with geostatistics, multivariate statistics, or landsc ape models, complex relationships can be elucidated and predicted. 4. To a certain extent, the tools discussed above have only automated fun ctions that were previously performed manually. This suite of tools ha s improved the ability of aquatic ecologists to examine relationships and test theories over larger, more heterogeneous regions than were pr eviously possible. 5. At the local, state and federal level, managemen t and regulatory frameworks are currently being re-evaluated to incorp orate this new perspective in resource management and policy decision making. 6. We will discuss current and future trends in technologies a nd tools used for aquatic ecosystem research, and the use of technique s as they are applied in these regional assessments are also discussed .