Limnological Report – 03 Long-Term Monitoring Program

Crater Lake Limnological Studies Final Report
 Long-Term Monitoring Program

 

The 10-year limnological study of Crater Lake revealed many of the components and processes important to lake clarity and to the dynamics of the lake ecosystem as a whole (Table 1). Although the relative importance of these components was well documented in many instances, many questions were generated which could not be addressed in sufficient detail within the scope of the program. This shortfall poses a problem because several human-related activities were identified which may have negative impacts on the lake (Table 2). Crater Lake is a unique lake from a global perspective, and it is highly valued both nationally and internationally. Responsibility for management of such a system should be a priority. Furthermore, the long-term data set that now exists for the lake has great scientific value for understanding processes that are common to all aquatic systems. Few pristine lakes have received such extensive study. The scientific value of these data will grow immensely if additional data can be added. The National Park Service, the agency charged with maintaining the pristine condition of the lake, must regulate human activities within the context of existing information and regulations, and simultaneously support the collection of additional information. Long-term monitoring of selected features of the lake system coupled with special short-term studies is needed for additional information for management and scientific purposes.

Table 1. A rating of the importance of selected processes or components of the Crater Lake ecosystem in relation to knowledge of lake clarity and the lake system. A rating of the level of knowledge of the processes and components is included.

Component or Process

Relative Importance to Understanding Lake Clarity

Relative Importance to Understanding the Lake System

Level of Knowledge

Lake level

Moderate

Moderate-High

Moderate

Water budget

Moderate

High

Moderate

Depth of surface mixing in winter

High

High

Moderate

Thermal stratification

High

High

Moderate

Depth of surface mixing in fall

High

Moderate

Low

Abiotic particles: mudslides, avalanches, runoff & storm events

High

Low-Moderate

Low

Nutrient budget

Moderate

High

Moderate

Hydrothermal inputs

Low

High

Moderate

Organic detritus
Water column
Benthic

Moderate
Low

High
High

Moderate
Moderate

Nutrient upwelling from the deep lake

High

High

Moderate

Spring 42 nitrate – N

Low

Low

High

Atmospheric deposition
Nutrients
Particles

Moderate
?

High
Low-Moderate

Moderate
Low

Particle flux

Moderate

High

Moderate

Boat and automobile Emissions/Petroleum wastes

?

?

Low

Phytoplankton production dynamics

Moderate-High

High

Moderate

Zooplankton production dynamics

Low-Moderate

High

Low-Moderate

Benthic flora (production & nutrient dynamics)

Low

High (?)

Low

Benthic fauna (production dynamics)

Low

Moderate

Low

Fish production dynamics

Low-Moderate

High

Low-Moderate