Long-term drop in Caribbean marine export productivity with the demise of the Central American Seaway

Author(s): Norris, R. D.; Trumbo, S. K.
Author Affiliation(s): Primary:
Scripps Institution of Oceanography, La Jolla, CA, United States
Volume Title: AGU 2015 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2015; American Geophysical Union 2015 fall meeting, San Francisco, CA, Dec. 14-18, 2015. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: The progressive closing of the Central American Seaway ∼3-7 Ma substantially altered the surface ocean salinity, nutrient content, and biology of the Caribbean Sea and Eastern Equatorial Pacific Ocean. Data from fossil plankton, reef development and oceanographic models of the shoaling Central American Seaway suggest that there was a distinct change in Caribbean productivity with closure of the seaway, but there has not been a detailed comparison of export production between the two ocean basins. Here we show that export production gradually decreased in the Caribbean starting about 2.7 Ma while remaining relatively stable in the eastern equatorial Pacific. Data are derived from 0-5.3 Ma XRF records of Caribbean Site ODP 999 and Pacific Site ODP 846 at ∼600-1000 year resolution. Caribbean export production falls during glacial phases in response to ventilation of the tropical thermocline by increasingly nutrient-starved Glacial North Atlantic Intermediate Water. In contrast, Caribbean production peaks during interglacials when nutrient-rich Antarctic Intermediate Water ventilates the tropical thermocline. Export production in both the eastern Pacific and Caribbean is governed mostly by high latitude nutrient sources as seen in the dominance of high latitude orbital forcing. The gradual intensification of Caribbean oligotrophy may be responsible for the well documented delay in extinction of Caribbean reef associated fauna relative to closure of the central American Seaway. The increasing nutrient starvation of the Caribbean during glacial events may also have rendered Caribbean reef corals unusually susceptible to anthropogenic nutrient loads in modern times.
Year of Publication: 2015
Research Program: ODP Ocean Drilling Program
Key Words: 07 Marine Geology and Oceanography; Atlantic Ocean; Caribbean Sea; Central American Seaway; Colombian Basin; Core; Leg 165; Marine sediments; North Atlantic; ODP Site 999; Ocean Drilling Program; Productivity; Sediments
Coordinates: N124437 N124437 W0784422 W0784422
Record ID: 2016050852
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