Aloha to the Pacific Remote Island Marine National Monument waters of Johnston Atoll. The sampling objectives have been accomplished and the scientists and crew onboard the NOAA Ship Oscar Elton Sette and are heading home. The bird colony (comprised mainly of Boobies) from Johnston Atoll Wildlife refuge provided frequent companions for us and have provided a running commentary on our sampling techniques.
The sampling efforts included:
• collecting enough fin-clip tissue samples from bottomfish in this area for DNA analyses
• capturing pelagic stage specimens of the bottomfish inhabiting this area
• conducting ocean measurements to characterize the physical environment that pelagic stage bottomfish may be associated with.
These samples, once analyzed, may lead to a better understanding of the environmental habitat of the bottomfish under investigation (these bottomfish species include the Hawaiian grouper “hapu’upu’u” and six species of deep-water snappers (“opakapaka”, “ehu”, “onaga”, “lehi”, “gindai”, and “kalekale”) and provide an understanding of the extent that populations between Johnston Atoll and the Hawaiian Archipelago are interconnected.
As the ship makes the journey back toward Oahu it will be stopping every night to continue collecting temperature, salinity, and dissolved oxygen chlorophyll measurements within the water column and pelagic stage specimens of the bottomfish being investigated. These samples will be collected using the same methods employed in the waters off Johnston Atoll. See previous bottomfish research expedition post for more information: http://bit.ly/1cGVagv
CTD and chlorophyll samples
Some of the major factors that play a role in primary productivity include ocean temperature, dissolved oxygen levels, and salinity. These contributing factors along with light availability and nutrients such as nitrates, phosphates, and iron influence the amount of chlorophyll or phytoplankton productivity in a given area. Measuring the amount of chlorophyll production coupled with ocean temperature, oxygen levels, and salinity along a depth gradient gives us an idea of how productive the area is and where it is occurring in the water column.
Aloha Sharks and Johnston Atoll, the next couple of blogs will talk about the close encounters we had with the local shark and our visit to Johnston Atoll itself. See next bottomfish research expedition post: http://bit.ly/17RGrdg