Has the role of atmospheric dust as a control on productivity in oligotrophic regions been overestimated?

Dust particles settling into the surface of open ocean environments are for years assumed to provide nutrients to these distant nutrient-limited areas.

Torfstein and Kienast (2018, see reference below) present a unique high-resolution coupling between dust concentrations (hourly resolution) and chlorophyll-a concentrations (daily time scale resolution) across a 4-year period in the deep, nutrient-poor water column of the north Red Sea, which seriously questions this hypothesis.

This long time series study reveals that there is no correlation between dust and surface chlorophyll-a concentrations, regardless of the time of year, or the possible lags between the dust settling and the oceanic response.

The authors conclude that the role of atmospheric dust as a control on productivity could have been previously overestimated.

18 Torfstein

Figure: The study took place in (a) the Gulf of Aqaba, northern Red Sea, and combined monthly and daily resolved records of  chlorophyl-a concentrations sampled at (b) the Interuniversity Institute for Marine Sciences (IUI) and station A (29°280N, 34°560E, water depth 700 m), respectively. The distance between the two sites is approximately 4 km. Dust time series were recorded at the IUI and its vicinity at weekly, daily and hourly resolution.  (c) A comparison between water temperatures and vertical chlorophyll-a (chl-a) concentrations at station A (monthly resolution), daily and monthly chl-a surface concentrations (μg/L), and dust concentrations (μg/m3) at a weekly, 6 hour and 1 hour time resolution, between January 2012 and August 2016, imply that no statistically significant correlation exists between dust patterns and chl-a concentrations. Click here to view the figure larger.

Reference:

Torfstein, A., & Kienast, S. S. (2018). No correlation between atmospheric dust and surface ocean chlorophyll-a in the oligotrophic Gulf of Aqaba, northern Red Sea. Journal of Geophysical Research: Biogeosciences, 123. https://doi.org/10.1002/2017JG004063

Latest highlights

Science Highlights

Trace metal quotas in small flagellates: diatoms are challenged!

Sofen and colleagues found that in natural plankton assemblages and in culture, small flagellates operated at the lower range of iron quotas.

14.09.2022

Science Highlights

A vivid picture of particle distribution and sources in the Arctic Ocean

Extensive description of particle concentrations and chlorophyll-a fluorescence distribution along Arctic GEOTRACES sections.

08.09.2022

Science Highlights

The Tonga arc, an iron boundary in the South West Pacific Ocean

As part of the TONGA GEOTRACES process study, Tilliette and colleagues identified high dissolved iron concentrations in the west of the Tonga arc.

31.08.2022

Science Highlights

Dominance of the benthic flux of rare earth elements on continental shelves

Deng and his colleagues focus on one of the largest land–ocean interfaces in Asia, the Changjiang River–East China Sea system.

30.08.2022

Rechercher