Zooplankton living in low-oxygen water

Jennifer Saltzman, Ph.D.
U.S. Naval Academy
Annapolis, Maryland

Wednesday, March 11, 1998
3:30 p.m.—Pacific Forum

We all know that we need oxygen in order to live. We breathe in oxygen from the air while marine invertebrates get their oxygen from the water. At mid depths in all oceans, the amount of oxygen in the water is at a minimum. In the eastern tropical Pacific, a prominent oxygen-minimum zone (OMZ), with less than 0.1 ml O₂/L, is found at about 100-1,000 meters. The purpose of this research was to determine which zooplankton live in the low-oxygenated waters of the OMZ and their abundance and distribution within the water column. I will discuss the trends in the vertical distribution of zooplankton and the surprising secondary peak in zooplankton abundance at the depth where oxygen begins to increase.

The eastern tropical Pacific has often been described as a biogeographical province. I will present several new species of zooplankton identified from this research. One is an abundant Pleuromamma copepod which shows dimorphic asymmetry. Another new species is a near-bottom opossum shrimp, or mysid. This research was conducted near the seamount Volcano 7, an island which never reached the sea surface. The life history and abundance of the mysid living in the OMZ on the seamount will be discussed. Morphologically this species is different from previously described species, yet the life history traits examined are similar to other bathypelagic and benthopelagic mysids.

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