When Black first began publishing comparisons of tree rings and the otoliths or ear bones of long-lived fish, he attracted the attention of climate change scientists.
"We found that chronologies for rockfish living at the 300-meter depth in the Pacific strongly related to tree-ring chronologies in the Cascade Mountains as well as to Pacific geoduck along the coast," Black said.
That study, recently published by Black in the professional journal Marine Ecology-Progress Series, showed that climate synchronized the growth of organisms from the continental shelf to alpine forests.
"The next step was to use the longest-lived organisms trees and the geoduck to tell us about climate prior to the start of instrumental records," Black pointed out.
Sea surface temperatures affect climate on land and when there is a spike in average yearly temperatures, such as during an El Nino year, it can have a profound impact on both trees and marine life. In general, Black said, warmer temperatures boost metabolism in geoduck and result in greater growth rates. Warm sea surface temperatures also mean less snow in the Cascade Mountains and a longer growing season for Douglas-firs and other trees, which are reflected in wider growth rings.
The limiting factor in using growth rings to study climate change is the age of the geoduck specimens. Old-growth evergreens may reach 500 to 1,000 years in age, but geoducks rarely exceed 150 years.
"Scientists at the Canadian Department of Fisheries and Oceans are dredging up shells of dead geoducks fro
|Contact: Bryan Black|
Oregon State University