The School of Geography, Earth and Environmental Sciences organises a regular series of research seminars throughout the academic year to which everyone is welcome to attend. Speakers - both external and internal to the University - will talk on topics related to all aspects of Earth Sciences.
Today's speaker is Dr Christopher Smart from the University of Plymouth.Planktic foraminifera provide useful information about past marine environments, and their distribution, abundance and isotopic composition are commonly used for reconstructing past oceanic conditions. The Miocene was a time of major changes in the ocean-atmosphere system and foraminifera provide key information about the environments during this important time interval. Biserial foraminifera were abundant in the early Miocene (~19-17 Ma) in the eastern Atlantic and western Indian Oceans. Morphologically, they were assigned to the benthic Bolivina, but stable isotope data show they were planktic, and therefore placed in Streptochilus. Modern Streptochilus globigerus is genetically identical to the benthic Bolivina variabilis, surviving in both planktic and benthic domains (tychopelagic). Such taxa may be able to evolve into true planktic species given favourable oceanographic conditions. The distribution of Miocene Streptochilus is examined and data suggest that they thrived during an interval with locally abundant nutrients. The widespread occurrence of areas with a food-rich, deep-thermocline niche may have provided the environmental trigger for these forms to invade the plankton.