A research team of marine biologists from Scripps Institution of Oceanography at UC San Diego and statisticians from Cal Poly has developed a new approach to better assess whale population data along the California coast.
The team examined microbial "ecological habitats" as predictors of how many filter-feeding whales occupied the California coast between 2014 and 2020, from San Diego to Morro Bay.
Traditional whale monitoring methods include visual surveys, photo identification, acoustic monitoring, satellite imagery and genomic methods.
Tracking whale populations has long been challenging due to wide-ranging migration areas and intermittent surface appearances.
The new approach uses environmental DNA, or eDNA, collected from seawater samples.
Seawater is filtered, DNA from organisms in the water is extracted, and specific genetic markers are amplified and sequenced. Researchers can then identify organisms present by matching sequences to reference databases.
“The concept of this project was to try and find an indirect signal that’s based on ecological relationships in the microbial communities that are in the water and how they respond to macro-organisms, such as whales,” said Trevor Ruiz, a Cal Poly assistant professor of statistics and one of the study’s lead authors. “We developed a tailored approach, and while our methods are not off the shelf, they remain transferrable to prediction from microbial data more broadly, and along with our scientific findings we have provided a portable software implementation of the methods to lower barriers to adoption for other researchers who might be interested in applying our approach to other problems.”
The study found that predictions of whale densities based on microbial communities were on average 53% more accurate than traditional forecasts.
