Changes in marine dinoflagellate and diatom abundance under climate change
Hinder SL, Hays GC, Edwards M, Roberts EC, Walne AW, and Gravenor MB
Imagine looking at your garden one morning and finding that the
grass had suddenly been replaced by bushes. Far fetched ? You might
think so but changes of this magnitude have recently been reported
in the biology of the North Atlantic with a dramatic switch in the
prevalence of dinoflagellates and diatoms, two groups that include
many of the microscopic planktonic plants that lie at the base of
the food chain.
The findings, published in Nature Climate Change by a team
of researchers from Swansea University and the Sir Alister Hardy
Foundation for Ocean Science, show that this shift from
dinoflagellates to diatoms is partly driven by increases in water
temperature which are a well known part of global warming. But more
unexpected was the discovery that the plankton shift is also
strongly driven by an increase in the windiness in the North
Atlantic region over the last 50 years. This increase in windiness
is something that is often overlooked.
In the ocean, windiness promotes vertical mixing of the water,
which in turn has profound impacts on surface nutrients levels and
the vertical distribution of plankton. In general, windier
conditions seem to favour diatoms over dinoflagellates. The new
patterns show major shifts in the distribution of economically
important species known to cause harmful effects through toxin
poisoning. The wider implication of this discovery are not fully
known, but the switch from dinoflagellates to diatoms is likely to
have propagated up the food chain to impact much larger animals
such as fish and whales.