Cache Slough water quality monitoring station. Courtesy USGS
A recent test found more than 250 chemicals in the Delta’s Cache Slough, but "Dr Doom" says figuring out what they all are, and their concentrations, is beside the point in our efforts to understand stressors on native fish resilience.
“Knowing the effect on the fish is more informative than knowing which chemicals may be causing it,” says UC Davis’ Richard Connon (whose colleagues gave him his sinister title), referring to taking an ecological rather than regulatory perspective on fish health, and also to the less obvious sublethal effects of contaminants on fish behavior and reproduction. Connon is the lead author of a wide-ranging journal article
in the December 2019 issue of SFEWS on how to better focus contaminants research in the Delta, and how to use more advanced tools to get at the synergistic and additive effects of multiple contaminants and stressors. Despite decades of monitoring, gigabytes of available data, and significant regulatory oversight, there remains “major uncertainty” on the extent of these effects, according to the article. The article also highlights the gap between assessment techniques currently used by regulators and the more advanced techniques now at the fingertips of forward-thinking scientists.
The article describes an array of advanced analytical tools for getting at the complexities. These include “high-throughput screening” and “rapid throughput bioassays,” which can speed up costly and time-consuming testing of both water samples and biological effects. Some of the tools detailed go by names unfathomable to the non-scientist (in-silico analyses, Omic approaches, bioinformatics, eDNA metabarcoding…). Taken together, however, the 22 pages compiled from 27 co-authors clearly point to the synthesis and dedication required ahead to make useful recommendations to Delta managers. “Contaminants are always going to end up in waterways, but if we know which locations are having the worst effects, maybe we focus our efforts there, and also provide organisms with respites and refuges so they can better cope with all these stressors,” says Connon. “… like putting a fish in a spa or on a treadmill so they can build up their fitness.”