E.V. Nautilus Expedition - Day 2 - East Node deploying hydrophone platforms

Date: September 14, 2015     Time: 8:57am PT  

Location: East Node, Strait of Georgia, BC Canada

Today the E/V Nautilus is in the Strait of Georgia at the East Node, in sight of Tsawwassen. The ship is deploying two hydrophone platforms for Ocean Networks Canada. The platforms work together to track noises in the Strait of Georgia. This audio can be used by scientists to hear what wildlife and ship traffic is in the area. The area has a diversity in life that including whales, dolphins and salmon. The Tsawwassen / Vancouver area also has the busiest port in Canada. Finding how much the human made noises is affecting marine life in the Strait of Georgia is important to maintaining the ecosystem here.

The hydrophone platforms have some interesting features in the their design to lower acoustic volume. Over the hydrophone is a yellow sock, a piece of fabric, which keeps the water flow off the hydrophone. It's like if someone were wearing a headset mic without foam covering the microphones' diaphragm. If  the person blew on the microphone, there would be a loud wind noise coming out over the speakers. But, if they put the foam back on the microphone there would be less wind noise on the audio. The same is happening on the hydrophone with the yellow sock, but instead of wind, it's water flow.

Another interesting feature is the way the platform keeps the support pipes from vibrating and making more noise for the hydrophone to pick up. The pipes are wrapped in rope and covered in black tape to hold the rope in place. This breaks up the water flow around the pipes, minimizing the vibrations, which the hydrophone would pick up. The whole platform is designed to get the best acoustic audio.

Ocean Networks Canada has audio clips on their website with a variety of underwater sounds. Some of the sounds include wildlife, like whales and dolphins. Interestingly, in one Arctic location, the hydrophone was even able to hear the ice breaking! Other hydrophones have been known to pick-up earthquakes as they are coming into the area. Here is a link to the sounds on the Ocean Networks Canada website. http://www.oceannetworks.ca/sounds-deep

Tomorrow we will be heading back over to the Delta Dynamics Observatory Laboratory where a platform will be brought back on ship for repair and then redeployed.