So what does science at sea look like?
Here’s a look at a few of our operations in action: CTD casts, fluorometry, trawling, passive acoustic monitoring, and visual marine mammal observations.
CTD casts and fluorometry
Throughout the Kona IEA survey, we are conducting sunrise and sunset CTD casts. These casts measure conductivity (to determine salinity), temperature, pressure (to determine depth), dissolved oxygen, and fluorescence. We also collect water samples at ten depths as the casts ascend.
Caption: The CTD sensors and bottle rosette. In the center are a number of sensors. The bottles around the outside are triggered to close at specific depths as the rosette ascends.
Caption: After CTD casts, we filter the water samples to measure the amount of chlorophyll at each depth sampled. Here, scientists Kaile’a Carlson and Eric Mooney (from left) filter water in the wet lab.
Caption: After filtering, the filters are placed in acetone to extract the chloropigments from the filters. Here, scientist Kaile’a Carlson preps the acetone to be run through our fluorometer.
Our trawling operations are now complete, but here’s a look at how the trawls were conducted.
Caption: The Sette’s deck crew and members of the science party hauling in the trawl net.
Caption: Clockwise from left, scientists William Truong, Melanie Abecassis, Jon Martinez, Adam Renick, and Johanna Wren detaching the trawl net’s cod end. The cod end is the very end of the net where all the catch accumulates.
Caption: From left, scientists Jon Martinez and William Truong weighing the total trawl catch before sorting it.
Caption: From left, scientists Jon Martinez, Melanie Abecassis, and William Truong sorting the trawl catch in the Sette’s wet lab.
Passive acoustic monitoring and visual marine mammal observations
To detect marine mammals, we tow a hydrophone array behind the ship. The clicks and whistles detected by the array are amplified and transmitted back to the ship. Through listening to these detections and plotting their range and bearing from the ship (not shown), it is possible to determine the locations of groups of marine mammals. During daylight hours, scientists conduct visual observations to assist in determining the location of marine mammals.
Caption: Scientist Melanie Abecassis and Teacher-at-Sea Adam Renick listen to the array and watch a spectrogram of the sounds being collected.
Caption: Scientist Kaile’a Carlson looks out through the “big-eye” binoculars on the Sette’s flying bridge.
Thank you to scientists Jessica Chen, Eric Mooney, and Chad Yoshinaga for the photos used in this blog post!