On Monday, we had a second chance to help out with preparing nitrogen enriched water for nitrogen fixation incubation experiments. We were also able to troubleshoot replacing nitrogen gas canisters, and learned more about the regulators HOT uses for their compressed gas.

On Tuesday, we toured the Hawai’i Institute of Marine Biology (HIMB) on Moku o Lo’e, or Coconut Island. It was a great chance to see the northern side of Oahu, as well as learn more about current research outside of the HOT team!

We toured a lab growing coral in different conditions, to simulate future changes in climate, as well as to preserve endangered species and identify resilient corals.

We also toured the Marine Conservation Innovation Group (MCIG) lab. One of their projects has been to design structures that can help improve coral recruitment and survivorship. They tested a variety of different shapes by 3D printing them with ceramic. They found that a spiral shape was the most successful design, and created scaled-up versions of the spiral shape out of concrete using custom molds. The cement coral habitats were recently attached to an even larger breakwater structure and deployed, to reduce wave force and erosion with rising sea levels, as well as to provide critical habitat. It was really cool to see all of the different designs, as well as the tools and 3D printers used to create these structures!

Finally, we had the chance to learn more about some local invertebrates, including sea cucumbers!

We finished up the day by heading back to campus and attending a pre-cruise meeting.

On Wednesday, we learned how to disassemble and check the electronic and mechanical components of a Sea-Bird SBE 32 Carousel Water Sampler. In the process of disassembling the carousel, one of the bolts sheared off – so we switched to disassembling and checking a spare. We looked for corrosion, rust, or salt crystals on the electronics, and didn’t find any. We also inspected the O-rings and applied anti-seize to insure a good, watertight seal.

After we finished working with the CTD, we helped acid clean some equipment for our upcoming cruise.

On Thursday, we practiced RS232 serial cable splicing! We made a custom cable that can connect a CTD auxiliary port to a Photosynthetically Active Radiation (PAR) sensor, and a second custom cable that can connect a CTD auxiliary port to a BENTHOS altimeter. This will allow the HOT team to add these sensors alongside a typical CTD ‘fish’ and increase the amount and types of data collected with each cast! It was a lot of fun to get some hands-on electrical experience and make a product that will be useful for the HOT team in the future.

With each cable, we started by diagramming each end. In both cases, we were connecting a six-pin CTD cable to a four-pin instrument cable. Next, we cut back the protective cover and stripped each wire. Then, we checked which color wire was connected to each port using a multimeter. After that, we connected the corresponding wires based on the ports and colors we had previously determined using a Western Union Splice, and cut back the extra wires from the six-pin cable that we weren’t using. We applied a heat-shrink solder to the ends of the unused wires to seal them off. Then, we used traditional solder to solidify the connections between the other wires. Dan Fitzgerald emphasized the importance of keeping the connection hot while soldering to avoid a ‘cold solder’ which would be more brittle. We held the soldering iron under the splice and allowed the solder to flow through the wires to get a solid connection.

Next, we wrapped each connection with scotch fill, wrapped the wires together with more scotch fill, and finished off our cables with electrical tape.

On Friday, we helped load up the ship for our cruise on Sunday, and shadowed Dan Fitzgerald as he worked on the electrical cable termination. After loading, we met with Dr. Angelicque White to talk more about the HOT program as a whole.

It was another great week and I’m excited for our upcoming cruise – though also sad our internship is coming to a close! I have loved getting to know the team and working with them at sea and in the lab.