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Climatic Effects
on Oceanic DMS Producers
Wong, C.-S., Wong, S.-K. E., Pena, A. and
Levasseur, M. 2006. Climatic effect on DMS
producers in the NE sub-Arctic Pacific: ENSO on
the upper ocean.
Tellus
58B: 319-326.
Dimethylsulfide (DMS), which is derived from
its algal precursor dimethylsulphoniopropionate
(DSMP), is a climatically-important trace gas
that has its origin in the activity of certain
types of marine phytoplankton and is believed to
play a major role in keeping earth's temperature
within bounds that are conducive to the
continual existence of life. Very briefly, and
rather simplistically, in response to an initial
warming (caused by an increase in the air's CO2, the climate-stabilizing mechanism
begins with a warming-induced increase in the
productivity of certain marine phytoplankton,
which leads to a greater production of oceanic
DMS and its release to the atmosphere, which
boosts the number of gas-to-particle
conversions, increasing the atmosphere's
population of cloud condensation nuclei and,
ultimately, the albedos of marine stratus and
altostratus clouds via a narrowing of the cloud
droplet spectrum and a decrease in the mean
radius of the cloud droplets, both of which
phenomena tend to counteract the initial impetus
for warming.
From 1996 to 2001 the authors recorded DMS
concentrations and physical oceanographic data
at ocean stations P26 (50°N, 145°W) and P20
(49°34'N, 138°40'W) in the Northeast Pacific Ocean,
after which they analyzed the data in a number
of different ways. What was learned Wong's
work confirmed that as the sea surface
temperature of a region rises, "the
stratification of the upper water column
intensifies and oceanic upwelling weakens," such
that "in the nutrient-rich waters of the
sub-Arctic Pacific, higher stratification and
shallower mixed layer favor the growth of
small-sized phytoplankton such as flagellates,
dinoflagellates and coccolithophorids." And
noting that "most prolific DMSP producers are
members of these phytoplankton groups," they say
that, "consequently, the local ecosystem is
shifted towards one with structure and function
adapted to [increasing] production of DMSP and
DMS."
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