Atmospheric Deposition Effects on Plankton Communities in the Eastern Mediterranean: A Mesocosm Experimental Approach
Résumé
The effects of atmospheric deposition on plankton community structure were
examined during a mesocosm experiment using water from the Cretan Sea (Eastern
Mediterranean), an area with a high frequency of atmospheric aerosol deposition events.
The experiment was carried out under spring-summer conditions (May 2012). The
main objective was to study the changes induced from a single deposition event,
on the autotrophic and heterotrophic surface microbial populations, from viruses to
zooplankton. To this end, the effects of Saharan dust addition were compared to the
effects ofmixed aerosol deposition on the plankton community over 9 days. The effects of
the dust addition seemed to propagate throughout the food-web, with changes observed
in nearly all of the measured parameters up to copepods. The dust input stimulated
increased productivity, both bacterial and primary. Picoplankton, both autotrophic and
heterotrophic capitalized on the changes in nutrient availability and microzooplankton
abundance also increased due to increased availability of prey. Five days after the
simulated deposition, copepods also responded, with an increase in egg production.
The results suggest that nutrients were transported up the food web through autotrophs,
which were favored by the Nitrogen supplied through both treatments. Although, the
effects of individual events are generally short lived, increased deposition frequency
and magnitude of events is expected in the area, due to predicted reduction in rainfall and increase in temperature, which can lead to more persistent changes in plankton
community structure. Here we demonstrate how a single dust deposition event leads
to enhancement of phytoplankton and microzooplankton and can eventually, through
copepods, transport more nutrients up the food web in the Eastern Mediterranean Sea.
Domaines
Milieux et Changements globauxOrigine | Fichiers éditeurs autorisés sur une archive ouverte |
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