1982 - 2002; ill., maps; Title covers calendar years 1990-2002; Bibliographic description is based on 1990 annual report; CA 9000-8-0006 Subagreement 8; Includes bibliographic references; Issues lack volume numbering
Executive Summary Limnological studies of Crater Lake were initiated by the National Park Service (NPS) in 1982 in response to an apparent decline in lake clarity and possible changes in characteristics of the algal community. Congress passed Public Law 97-250 in the fall of 1982, and thereby authorized and directed the Secretary of the Interior to conduct a 10-year limnological study of the lake. The study revealed many of the components and processes important to lake clarity and to the dynamics of the ecosystem. In no case, however, did any component of the lake system exhibit unidirectional or exponential changes associated with increasing lake productivity. Thus, the researchers concluded that the lake was in pristine condition, with the exception of the consequences of introduced fishes. Although results of the 10-year study documented the importance of many lake components to the dynamics of the lake, many questions were generated that could not be addressed in sufficient detail within the scope of the program. This information shortfall was a concern for several reasons. First, several human-related activities that may have negative impacts on the lake were identified. Crater Lake is a unique lake from a global perspective and is highly valued nationally and internationally. Responsible management of this system is a priority of NPS, and the NPS requires additional information to be effective in its management efforts. Second, the long-term data set that existed in 1993 was of great value for understanding processes that are common to all lake systems. The scientific value of these data would grow immensely if additional data could be added. Clearly, long-term monitoring of selected features of the lake system, coupled with special short-term studies, is needed for management and scientific purposes. In response to these needs, Crater Lake National Park initiated a long-term limnological monitoring program in 1993, which was base-funded in 1994. iii. Results from the studies in 1997 continue to illustrate that Crater Lake is a complex, dynamic, and unproductive (oligotrophic) system. Although no long-term or undirectional changes were observed, water clarity, chlorophyll, primary production, plankton abundance and species assemblages, and kokanee salmon biomass exhibited considerable variation during the period from 1978 to 1997. The monitoring program continues to emphasize the interrelationships among environmental, terrestrial, anthropogenic, and aquatic components of the lake system. Future work will continue to emphasize an ecosystem approach and the additional development of conceptual models.
Executive Summary Limnological studies of Crater Lake were initiated by the National Park Service (NPS) in 1982 in response to an apparent decline in lake clarity and possible changes in characteristics of the algal community. Congress passed Public Law 97-250 in the fall of 1982, and thereby authorized and directed the Secretary of the Interior to conduct a 10-year limnological study of the lake. The study revealed many of the components and processes important to lake clarity and to the dynamics of the ecosystem. In no case, however, did any component of the lake system exhibit unidirectional or exponential changes associated with increasing lake productivity. Thus, the researchers concluded that the lake was in pristine condition, with the exception of the consequences of introduced fishes. Although results of the 10-year study documented the importance of many lake components to the dynamics of the lake, many questions were generated that could not be addressed in sufficient detail within the scope of the program. This information shortfall was a concern for several reasons. First, several human-related activities that may have negative impacts on the lake were identified. Crater Lake is a unique lake from a global perspective and is highly valued nationally and internationally. Responsible management of this system is a priority of NPS, and the NPS requires additional information to be effective in its management efforts. Second, the long-term data set that existed in 1993 was of great value for understanding processes that are common to all lake systems. The scientific value of these data would grow immensely if additional data could be added. Clearly, long-term monitoring of selected features of the lake system, coupled with special short-term studies, is needed for management and scientific purposes. In response to these needs, Crater Lake National Park initiated a long-term limnological monitoring program in 1993, which was base-funded in 1994. iii. Results from the studies in 1997 continue to illustrate that Crater Lake is a complex, dynamic, and unproductive (oligotrophic) system. Although no long-term or undirectional changes were observed, water clarity, chlorophyll, primary production, plankton abundance and species assemblages, and kokanee salmon biomass exhibited considerable variation during the period from 1978 to 1997. The monitoring program continues to emphasize the interrelationships among environmental, terrestrial, anthropogenic, and aquatic components of the lake system. Future work will continue to emphasize an ecosystem approach and the additional development of conceptual models.