Bomb radiocarbon - White abalone
Bomb radiocarbon dating of white abalone
Published in Marine and Freshwater Research 2013
Bomb radiocarbon dating of white abalone (Haliotis sorenseni): investigations of age, growth and lifespan
Understanding basic life history characteristics of white abalone (Haliotis sorenseni), such as estimated life span, is critical to making informed decisions regarding the recovery of this endangered species. All predictive modeling tools used to forecast the status and health of populations following restoration activities depend upon a validated estimate of adult lifespan. Of the seven Haliotis species in California, white abalone is considered to have the highest extinction risk and was the first marine invertebrate listed as an endangered species under the Federal Endangered Species Act (ESA). Lifespan was previously estimated from observations of early growth, but no study has generated ages for the largest white abalone. To address questions of age and growth, bomb radiocarbon (∆14C) dating was used on shells from large white abalone. Measured bomb ∆14C levels were compared to regional ∆14C reference records to provide estimates of age, growth and lifespan. Bomb radiocarbon dating indicated growth was variable among individuals with a maximum estimated age of 27 years. The findings presented here provide support for previous age and growth estimates and an estimated lifespan near 30 years. These age data support the perception of a critical need for restoring the remnant aging and potentially senescent population.
Authors: Allen H. Andrews, Robert T. Leaf, Laura Rogers-Bennett, Melissa Neuman, Heather Hawk, and Gregor M. Cailliet.
If you would like to know more about the white abalone and its current status as an endangered species and the population recovery effort, follow the link to the NOAA Fisheries Office of Protected Resources.
Bomb Radiocarbon and the northeastern Pacific Ocean
This figure incorporates a series of radiocarbon records and individual samples from locations along the Northeastern Pacific Ocean margin. These data exemplify the complicated nature of the bomb radiocarbon signal and its timing in regions of complex oceanography. Upwelling due to geostrophic flow and current interactions with bathymetry lead to mixed sources of radiocarbon (depleted deep-water and mixed surface water). Hence, the post-bomb peak and decline periods are highly variable through time.
In addition to the research performed on white abalone, a series of references for the Southern California Bight (SCB) and farther abroad were assembled to describe what the rise of ∆14C may have been for the region. Some are from afar and are simply references that are the closest complete records from regions with similar coastal oceanography (yelloweye rockfish and Pacific halibut). Samples specific to the SCB were a mix of dissolved inorganic carbon (DIC) measurements and abalone shells analyzed in this study. In addition, a rare season record from Half Moon Bay was included to show how much ∆14C can vary seasonally along the California Coast during the year. This fluctuation of >100 per mille in a single year provides an idea of how a measurement from a fish or a shell cannot be tied to a specific date. While the rise of ∆14C appears to be similar in timing, the post-bomb record was highly variable. Note that the abalone shell samples also vary at this magnitude post-peak.
