The technical and scientific background information was generally well presented. The use of mussels as bioindicators has a long history in the biomonitoring literature. However, the proposal does not adequately address its limitations. Mussels in the Pacific Northwest usually do not occur in high gradient headwater streams, particularly those prone to frequent bedload movement. Thus, the distribution alone makes the mussel group less suitable for use in monitoring than other taxa. Furthermore, numerous other proposed projects have discussed the fact that the mussel group is in jeopardy. In addition, the areas selected for study (Upper Columbia, John Day, Upper Salmon, and estuary) are all within the anadromous fish zone. It would seem that mussels could provide biomonitoring value to resident fish areas as well, but none were chosen.

In addition, a filter feeder will not have high concentrations of most contaminants, even if they are present. Other ephemeral contaminants will depend upon the time of the year the sample was collected (spray season), and can be more easily completed with a semi-permeable membrane device (SPMD) placed in the water. The Mussel Watch Program along the coast came into existence before the advent SPMDs, which can now be used for monitoring purposes (independent of mussel distribution). SPMDs collect contaminants from water just like the filter-feeding mussels. The ISRP was surprised that no contaminants were scheduled for analyses, although some samples were going to be archived for possible analyses.

It would seem like the condition of the mussels will be so dependent upon local conditions that it would be very difficult to compare locations and associated habitats in a meaningful way to obtain overall patterns and to understand what is responsible for them, i.e., age ratios, growth rates, other body measurements, etc.

No single approach is best for monitoring contaminants in the Columbia River Basin, but a combination of SPMDs, selected fish species and top predators (mammalian or avian) may be effective. Top predators should be evaluated if there is concern about contaminants that biomagnify up the food chain. With certain contaminants, the timing of collections (e.g., related to spray season for non-persistent pesticides) is very important.

Relationships to other projects is clearly articulated. However, some of the proposed work in the John Day River may duplicate John Day mussel research in the ongoing BPA-funded study. A weakness of the proposal is a lack of detail on how contaminant levels in mussel tissues will be related to pollution sources. As described in the proposal, there does not seem to be a strong connection with water quality monitoring agencies such as EPA, Oregon DEQ, and Washington DOE. Such a partnership would help this project.

A couple of the tasks (e.g., 2.d) call for physiological studies conducted in the lab, where it will be very hard to duplicate typical diurnal and seasonal variability in basic parameters such as temperature. For contaminants, this issue becomes even more difficult because many contaminants are pulsed into the drainage system. One approach the investigators might consider is devising a mobile laboratory that can travel to the sites and utilize flow-through water supplies, making it much easier to simulate natural conditions. Such a setup can provide a more controlled environment than the mussel caging studies without sacrificing some of the natural environmental variability.