The likelihood of observing dust-stimulated phytoplankton growth in waters proximal to the Australian continent

• Published in: Journal of Marine Systems
• Main Authors: Cropp, RA, Gabric, AJ, Levasseur, M, McTainish, GH, Bowie, AR, Hassler, CS, Law, CS, McGowan, H, Tindale, N, Viscarra Rossel, R
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier Science Bv 2013
• Subjects: Earth Sciences; Oceanography; Chemical Oceanography; Southern Ocean
• Online Access: https://doi.org/10.1016/j.jmarsys.2013.02.013; http://ecite.utas.edu.au/84462

We develop a tool to assist in identifying a link between naturally occurring aeolian dust deposition and phytoplanktonresponse in the ocean. Rather than examining a single, or small number of dust deposition events, wetake a climatological approach to estimate the likelihood of observing a definitive link between dust depositionand a phytoplankton bloomfor the oceans proximal to the Australian continent.We use a dust stormindex (DSI)to determine dust entrainment in the Lake Eyre Basin (LEB) and an ensemble of modelled atmospheric trajectoriesof dust transport fromthe basin, themajor dust source in Australia. Deposition into the ocean is computed asa function of distance fromthe LEB source and the local over-ocean precipitation. The upper ocean's receptivity tonutrients, including dust-borne iron, is defined in terms of time-dependent, monthly climatological fields forlight, mixed layer depth and chlorophyll concentration relative to the climatologicalmonthly maximum. The resultantlikelihood of a dust-phytoplankton link being observed is then mapped as a function of space and time.Our results suggest that the Southern Ocean (north of 45S), the North West Shelf, and Great Barrier Reef areocean regions where a rapid biological response to dust inputs is most likely to be observed. Conversely, dueto asynchrony between deposition and ocean receptivity, direct causal links appear unlikely to be observed inthe Tasman Sea and Southern Ocean south of 45S.