Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10117747 | Continental Shelf Research | 2018 | 41 Pages |
Abstract
Shoaling of the saturation horizon for aragonite in the California Current System has been well-documented; however, these reports are based primarily on surveys conducted in waters off the continental shelf. Here we characterize, for the first time, regional spatial and seasonal patterns in aragonite saturation state (Ωarag) in the shallow, nearshore waters of the southern California continental shelf through a series of synoptic surveys. Spectrophotometric pH and total alkalinity samples were collected quarterly from 72 sites along the shelf for two years. Samples were collected using Niskin bottles deployed at 2-3 depths per station (surface, mixed layer, and near-bottom) to characterize site extremes in Ωarag (highest values near the surface, lowest at depth). Ωarag in bottle samples ranged between 3.0 and 0.54 and was strongly associated with density; average Ωarag from samples collected in the top 10â¯m was 2.5 compared to an average of 1.1 in samples below 100â¯m. The average depth of corrosive waters (Ωarag < 1) was interpolated for the shelf from the bottle data and was estimated to be an average of 100â¯m regionally, though there were instances when the saturation horizon rose to less than 20â¯m depth, primarily in the northern part of the coast during the spring. Ωarag was strongly correlated with dissolved inorganic carbon and dissolved oxygen indicating that patterns in Ωarag were linked to biological processes. The seasonality and spatial patterns we observed on the continental shelf were comparable to those observed by the California Cooperative Fisheries Investigations (CalCOFI) and West Coast Ocean Acidification (WCOA) programs in offshore southern California waters, suggesting that oceanic forcing is a strong driver defining broad patterns in aragonite saturation state on the shelf.
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Geology
Authors
Karen McLaughlin, Nikolay P. Nezlin, Stephen B. Weisberg, Andrew G. Dickson, J. Ashley T. Booth, Curtis L. Cash, Adriano Feit, Joseph R. Gully, Meredith D.A. Howard, Scott Johnson, Ami Latker, Michael J. Mengel, George L. Robertson, Alex Steele,