Review of the Historical GCMRC Aquatic Food Base Program
Approach: Monitor benthic algae, invertebrates, and organic material, and track changes in their composition and mass with changes in flow regimes.
Science Advisors findings:
- The reviewers found the overall direction of the program (as specified by the RFPs) in inadequate for meeting the food base information needs required to inform GCD AMP management decisions.
- The reviewers were in full agreement, that even given the science requested by the RFPs, the NAU work had significant weaknesses that should have been corrected as regards accepted methodological, statistical, and analysis/interpretation standards.
Review of the GCMRC 2001 Program Evaluation: Protocol Evaluation Panel (PEP) Report of the Aquatic Food Base Science Program
Conclusion:
- The historical food base program was characterized as insufficient to provide clarification on ecosystem linkages.
- A direction was proposed towards a total system carbon budget and food web elucidation for clarification of linkages, possibly through stable isotope work.
- Assessments of impacts of carbon from all sources (autochthonous and allochthonous) is critical to an ecosystem level understanding of the aquatic food base.
- While there may be some desire to establish or continue some routine monitoring of biomass, it is clear that the variability of space and time in the standing stocks of algae and invertebrates is so great that it is impossible to make inferences on the status and trends of the food base using the type of approach employed over the last 13 years.
- The SAs agree with the PEP Report that a modeling framework might be appropriate, and should include putative trophic linkages as well as the physical drivers in the system (e.g., temperature changes, flow, etc.).
Recommendations:
Move to evaluations of production processes, energetics, ecosystem level linkages, etc.
GCMRC 2003 Proposal for Future Food Base Science
- Assess ecosystem processes
- Pursue issues of foodweb productivity and energetics
- Evaluate requirements of upper trophic levels (i.e. HBC)
- Quantify where nutrients come from
- Importance of external versus internal carbon sources, and
- the food web dynamics for very different reaches of the river.
- An entirely new science effort is recommended.
- Shift in focus from biomass and standing stocks to energetic considerations and fluxes.
- Maintain hypothesis driven research
- Stable isotope work to determine how energy is transferred up the foodweb.
|
