Publication Date:
2013-11-19
Description:
[1] Increasing anthropogenic atmospheric deposition of nutrients, trace metals and toxic substances to oceans may synergistically enhance or inhibit some specific phytoplankton growth, subsequently modulating primary productivity. In this study, on-board incubation experiments were performed in the Southern Yellow Sea in the spring of 2011 to explore the responses of micro-, nano- and pico-phytoplankton to various combinations of added substances. The water samples used were collected at a lower nutrient concentration zone with an N/P ratio of 10, where satellite data showed a bloom on the 11 th day after collection. The bloom also occurred in the control experiment on the 9 th -11 th days. We simulated atmospheric input by artificially adding Asian dust, rainwater, nitrogen (dissolved inorganic N), phosphorus (P) and iron (Fe). The addition of a large amount of Asian dust increased both the maximum concentration of chlorophyll a (Chl a) and the conversion efficiency index of N into Chl a (CEI) by ~40 % and ~30 %, respectively, compared to the control, indicative of promoting growth of the phytoplankton. However, no promotion effect on phytoplankton growth was observed when the addition of Asian dust was reduced to 10 % of the original amount. The addition of rainwater increased the maximum concentration of Chl a by ~40 % but decreased the CEI by ~40 %, indicating inhibition coexisting with promotion of some phytoplankton species. Moreover, the size-fractioned Chl a data showed that the inhibition effect pertained to nano-phytoplankton and occurred following the bloom (after the 8 th day).
Print ISSN:
0148-0227
Topics:
Biology
,
Geosciences
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