Kathy Schroeder, May 8, 2010

NOAA Teacher at Sea
Kathy Schroeder
Aboard NOAA Ship Oscar Dyson
May 5 – May 18, 2010

Mission: Fisheries Surveys
Geographical Area: Eastern Bering Sea
Date: May 8, 2010

CTD Water Samples 5/8

Today I was able to see a different type of equipment deployed. It is called a CTD (conductivity temperature depth). The CTD went down 150 meters. On the metal frame that holds the CTD are 12 water bottles with caps at each end. The frame is lowered with both end caps open.

Once at its depth the end caps are closed to take a water sample. This is then repeated at 5 different depths on its return to the surface. The water is then put into plastic containers of known volume, which are then taken to a filter (about the size of a quarter) that separates the microscopic plants called phytoplankton from the seawater. The filters with the phytoplankton are then frozen in small plastic vials to be sent to a lab in Seattle where they determine how much chlorophyll was on each filter. The amount of chlorophyll tells us how much phytoplankton was in the water at each depth. Another water sample taken from the CTD is to verify the salinity values measured by the CTD. We haven’t found much pollock the last few hauls. We are now finding Pacific cod, and of course krill and arthropods such as copepods, amphipods, barnacle nauplii. Amber spotted a Minke whale this morning. I hope to see one soon!