Shallow marine
calcifiers play an important role as marine ecosystem engineers and in the
global carbon cycle. Understanding their response to warming is essential to
evaluate the fate of marine ecosystems under global change scenarios.
A rare opportunity to
test the effect of warming on natural ecosystems is by investigating
heat-polluted areas. A research study headed by BGU's Prof. Sigal Abramovich, carried out by her PhD student Danna Titelboim,
in collaboration with Dr. Ahuva Almogi-Labin (Geological Survey of Israel),
Prof. Barak Herut (Israel Oceanographic and Limnological Research), and
Cambridge University investigated the growth and calcification of single cell
organisms called foraminifera.
Their results were just
published in the journal Global Change Biology.
Foraminifera are large
eukaryotic protists that thrive in the oceans, precipitate CaCO3 shells that
accumulate on the ocean floor in mass quantities, and are thus a major
component of the marine carbonate factory.
This study used
foraminifera that inhabit a thermally polluted coastal area in Israel, where
they are exposed to elevated temperatures reaching up to ~42°C in summer,
mimicking a future warming scenario.
Their results provide
the first direct field evidence that these foraminifera species not only
persist at extreme warm temperatures but continue to calcify and grow at
temperatures as high as 40°C. Their results also show a clear calcification
sensitivity to cold winter temperatures.
Their findings indicate
that under realistic future warming scenarios, calcification in some
foraminifera species will not be inhibited during summer. Furthermore, an
inhibition of their calcification at low temperatures indicates that the
temperature window for their calcification will be expanded throughout much of
the year and the role of heat-tolerant foraminifera in carbonate production
will most likely increase with the ongoing warming in future decades.
The research was funded
by the BMBF-MOST cooperation in Marine Sciences Grant, the Ministry of Energy,
and Water Resources and support provided to Danna Titelboim by the
Mediterranean Sea Research Center of Israel.
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Danna Titelboim, Aleksey
Sadekov, Ahuva Almogi-Labin, Barak Herut, Michal Kucera, Christiane Schmidt,
Orit Hyams-Kaphzan, Sigal Abramovich
“Geochemical signatures of benthic foraminiferal shells from a heat-polluted shallow marine environment provide field evidence for growth and calcification under extreme warmth”
