Trace Metals and the Ecology of Marine Cyanobacteria
Abstract
The marine cyanobacteria Synechococcus and Prochlorococcus are important primary producers in oligotrophic oceans. The abundance and cell division rates of these cyanobacteria can be influenced by trace metals such as iron and copper. Iron is an essential trace metal that is present in the high nutrient, low chlorophyll waters of the equatorial Pacific in extremely low concentrations. When these waters were enriched with iron, Prochlorococcus cell division rates doubled indicating that these cells were iron limited. Mortality rates nearly doubled as well and as a result cell numbers remained constant. Copper is also essential for growth, but in the Sargasso Sea it can be present in toxic, rather than limiting concentrations. We hypothesize that ambient copper levels may influence the relative abundance and cell division rates of Prochlorococcus and Synechococcus in the Sargasso Sea. Prochlorococcus isolates were more sensitive to copper than Synechococcus, and in the field there was a rough inverse correlation between Prochlorococcus abundance and free Cu2+. Net growth rates were substantially reduced when Prochlorococcus from environments where the in situ free Cu2+ was low were exposed to copper. The distribution of Synechococcus is more uniform and they were relatively copper resistant across a range of environments.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 2000
- Accession Number
- ADA384499
Entities
People
- Elizabeth L. Mann
Organizations
- Massachusetts Institute of Technology