In response to the Council’s December 4, 2014 request, the ISRP reviewed a revised proposal for the Yakama Nations’ Upper Columbia Nutrient Supplementation Project (#2008-471-00). The revised proposal is intended to address a condition placed on this project as part of the Council’s decision made on the project on May 12, 2010 and a follow-up review by the ISRP in February 2014 (ISRP 2014-2). In addition to the 2014 ISRP review, the ISRP has reviewed the project three other times (ISRP 2009-27, 2009-50, and 2010-8). In the 2014 review, the ISRP found that the project proponents’ submittal did not meet scientific review criteria and recommended that any future proposal be presented as a stand-alone study proposal that addresses the ISRP’s comments, especially those related to experimental design and statistical analysis.
Project short description:
This project evaluates the effects of nutrient addition on natural production of anadromous salmonids in Hancock Spring Natural Laboratory in the Methow River Basin. The project applies a food web approach to quantify energy flow through food webs, using both Trophic Basis of Production modeling and stable isotope analyses. The project also assesses the effects of habitat complexity on efforts to restore natural production. To scale findings, the project formalizes ecological mechanisms of energy routing in a mechanism-based model for understanding restoration effects on ESA-listed fish species.
The ISRP found that the revised proposal does not meet scientific review criteria.
Some of the concerns raised in the previous ISRP review were addressed in the revised proposal and in the point-by-point responses provided by the project proponents. For example, limiting the experimental treatment to analog additions reduced the issue of confounding effects from multiple types of treatments associated with the previous design.
However, the revised proposal still has a number of major flaws:
- The nutrient addition study will still be unreplicated, lacks a non-enrichment control, and suffers from a lack of independence between the restored and unrestored reaches. Reach 2 is immediately downstream of Reach 1. Any activities occurring in Reach 1 could impact conditions in Reach 2, including the addition of analogs to Reach 1 (i.e., Reach 2 will receive enrichment from both the analogs placed in this reach and any organic matter and nutrients transported from Reach 1). Therefore, it would not be possible to attribute any difference in response to enrichment with analogs between Reach 1 and Reach 2 to difference in physical habitat condition. The lack of an unenriched reference site will affect the ability to ascribe observed responses to the treatment rather than temporal effects. A before-after control-impact (BACI) design is needed to disentangle treatment and temporal effects. The lack of replication implies that any conclusions would be specific to this particular location and may not be applicable to other locations.
- The two study reaches appear to be physically very different, even before Reach 1 was restored (see comments below). This further increases concern about the validity of attributing any differences in food web responses to the habitat restoration actions that were undertaken before enrichment began.
- Hancock Springs is an unusual site at the landscape scale, as the proponents acknowledge in the proposal. Therefore, concerns remain about the applicability of the information generated at Hancock Springs to other systems in the Upper Columbia region. Using the Hancock Springs data to parameterize ecosystem models may aid, somewhat, in understanding the extent to which the responses observed at Hancock Springs can be applied to other sites. However, the application of models parameterized with data from a spring stream to systems with the variable flow and thermal regimes typical of non-spring streams will be highly uncertain. It is likely that knowledge gained from this project will be of limited value in improving restoration actions on other small tributaries.
Although a better understanding of food web response to various restoration actions remains a key knowledge gap across the Columbia Basin, the issues listed above indicate that Hancock Springs is not an appropriate location to conduct this type of research. Overall, the proponents have not provided a convincing argument that this project will provide new information that can be used by other researchers or managers.