In response to the Council’s December 13, 2013 request, the ISRP reviewed the Interim Project Progress Report (November 2013) for the Yakama Nations’ Upper Columbia Nutrient Supplementation Project (#2008-471-00). The progress report is intended to address a condition placed on this project as part of the Council decision made on May 12, 2010 that concurred with the ISRP recommendation on the project. Specifically, the ISRP found that the project had the potential to be a useful nutrient experiment (ISRP 2010-8). However, the ISRP recommended that a complete study plan was needed that included the following critical project components:
- identification of the form in which nutrients will be added
- power analyses of the detection of a response in fish production
- stable isotope work details
- securing of permits for sampling fish
The Council agreed with the ISRP and stated that these issues could be addressed over two to three years as the Yakama Nation gathered pre-treatment data. The Council noted that the information could then be included in an updated study plan by 2013 and submitted to the ISRP for review. Based on this understanding, the Council recommended to Bonneville to implement the pre-treatment activities and that implementation of the nutrient enrichment study depends on favorable scientific review of an updated study plan.
The ISRP notes that the study has changed considerably from the previously reviewed proposal. The revised proposal includes a set of pilot experiments on Hancock Springs to be followed by a nutrient treatment on a section of the Twisp River. The initial proposal was to add nutrients to a much longer reach of the Twisp River. As a result of the fundamental restructuring of the study, the ISRP feels it is appropriate to review this submission as a new project. Although we do provide comments relative to the four issues identified during the previous review, many of our comments concern the revised experimental design.
Recommendation
Does Not Meet Scientific Review Criteria
The ISRP recommends that any future proposal carefully consider the comments below, especially those related to experimental design and statistical analysis. Should a future proposal be developed, it should fully address the issues raised in this ISRP review and be presented as a stand-alone study proposal rather than combined with a progress report.
Summary
Nutrient enhancement has become an increasingly popular technique in the Columbia Basin over the last decade. However, the effectiveness of this technique is poorly understood. The authors propose to implement two, large-scale, unreplicated field experiments in an attempt to evaluate food web response to nutrient augmentation with carcass analogs. In addition, one of the study sites (Hancock Springs) also will evaluate food web response to habitat restoration and removal of brook trout. Unfortunately, in the ISRP’s judgment, the design of both the Hancock Springs and Twisp River components of this study are seriously flawed. The design issues appear to be fundamental problems that cannot be corrected by using different sampling or data analysis methods. Consequently, the ISRP does not believe the proposed studies, as they are currently structured, will provide a rigorous test of the potential benefits from habitat restoration, nutrient addition, and invasive species removal.
The ISRP did find the emphasis placed on food web response to the application of various restoration treatments a very attractive element of the study approach. We appreciate how difficult it is to compile the data required to generate the detailed energy flow analyses summarized in figures 21 and 22. In general, this aspect of system response to restoration treatments has not received the degree of attention that it should. Trophic response to all types of restoration designs, not just nutrient addition, may make an important contribution to the treatment effectiveness. A better understanding of this aspect of stream restoration will be very important in refining restoration strategies in the future. The project sponsors are to be commended for recognizing the significance of this issue.
The ISRP visited Hancock Springs during a field tour in 2013. The ISRP did feel this study site offered opportunities for a detailed study of system response to various experimental manipulations due to the manageable size of the study site and the wealth of data that were being collected on trophic system dynamics. However, the ISRP was not fully aware of the experimental design issues, detailed below, at the time of the tour. Review of the proposal made these problems evident.
See the full ISRP memo for detailed comments.
