Issues associated with the possible impairment of estuarine beneficial uses by copper need resolution. These are issues that must be resolved in the consideration of a site specific objective for copper and associated reassessment of the Bay segments. Two critical issues pertain to the appropriate indicator species that should be considered and the extent of copper organic complexation in San Francisco Bay.
The extent of the water quality impairment due to copper depends on the indicator species selected. Many types of marine algae are orders of magnitude more sensitive to copper than larger invertebrates. Current and proposed Federal criteria are driven by the latter, i.e., reproductive success of the blue mussel, Mytilus edulis. The only algae represented in the national dataset are diatoms, the most copper-tolerant species. Consequently, the significance of copper sensitive algae species, such as dinoflagellates and cyanobacteria, needs to be resolved.
An initial review of indicator organisms for South San Francisco Bay has been prepared by the City of San Jose and is currently being reviewed by the the Santa Clara Basin Watershed Management Initiative, Regional Board staff, and external scientists. This work can form the basis for selecting indicator organisms in the other bay segments. If copper sensitive algae species are selected, then a technical review of copper toxicity to algae should be conducted. In addition, a controlled study is needed to determine the extent to which ambient copper actually impairs plankton growth. That study should resolve copper toxicity from physical stressors, such as grazing and light limitation.
Complete review of indicator organisms applicable to all Bay segments.