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Friday, March 19, 2004, 4:00 pm in POST 723
Calcareous nannofossils in shelf
environments
By
Dr. Mario Cachao
University of Lisbon, Portugal
Calcareous nannoplankton comprises present day coccolithophores and other
phytoplankton groups. Coccolithophores form a major component of the extant
marine calcareous nannoplankton and are one of the main open ocean primary
producers. Traditionally considered oligotrophic they play a significant
role in the CO2-O2 exchanges between the ocean and the atmosphere,
seriously affecting both the biological and the carbonate pumps and
producing an additional feedback to climate changes. Each coccolithophore
is surrounded by small calcite more or less complex discs in the coccoliths
- which form a discontinuous calcareous shell around the living single
cell, representing the most important component of deep-sea sediments and
providing highly significant information for the interpretation of global
change in the geological record.
Mainly oceanic, the role of Coccolithophores in coastal environments is
gradually being investigated and several works have already addressed this
issue in distinct sectors of the coastal margin off Portugal. For almost a
decade we have been carrying out research on present day and Quaternary
coccolith distribution patterns on the neritic environments of the Western
Iberia shelf as well as inside paralic environments such as coastal lagoons
and estuaries. Our research led to the development of several models which
will be discussed during the presentation.
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