Dramatic Climate Change-Driven Impacts Documented Across Marine Life Spectrum

"This is the first evidence in the ocean that climate change can have dramatic effects on large-scale fisheries ecosystems," said Scripps Professor George Sugihara. "These are some very interesting consequences that people haven't really thought about. These warming events could actually cause a constellation of species that normally don't interact to begin to interact and that could have potentially large effects on what we think ought to be the natural ecosystem."
The study, led by Chih-Hao Hsieh while he was a student at Scripps Oceanography, and who is now at National Taiwan University, is based on data from the California Cooperative Oceanic Fisheries Investigations (CalCOFI), a program based at Scripps that has monitored the marine environment of the California Current for nearly 60 years. Hsieh, Sugihara and their coauthors used the CalCOFI database to decipher the sensitivity of fish habitats in response to climate-driven ocean warming.
To arrive at their results, the researchers studied quantities of larvae for 34 fish groups. Numbers and geographic locations of fish larvae - a quantity known as "biomass"-are indicative of the abundance of fish species. They compared that information with physical measurements, including water temperature.
Among their findings, the researchers describe a significant increase in the population of 25 fish groups from a cold period (1951-1976) to a warm one (1977-1998), including species such as dogtooth lampfish, longfin lanternfish, California lanternfish and Panama lightfish.
They also found that fish species that typically migrate vertically in the marine water column shifted geographically northward to colder waters, a change that wasn't seen in other fish that don't migrate as such in the water column. The authors speculate this may be because the upper layers of the water column warmed considerably more than deeper levels, leaving the bottom dwellers less impacted. Migrating species would have sensed the warming more readily and moved in response.