Tuesday, April 16, 2013

Our first acoustic recordings of a coral reef

A recorder about to be recovered using a lift bag (Photo: M. Kaplan)
Over the last two days we have deployed, retrieved, and redeployed 4 acoustic recorders. Late last night we looked at our first 24-hour recordings from one of our deployment sites - Tektite. This site has the most coral cover of our three sites and we expect that it will also have the most complex soundscape. A quick look through the recordings suggests a strong background noise produced by snapping shrimp, with a number of low-frequency fish sounds on record throughout the 24 hours. By deploying 4 recorders at each site, we're hoping to be able to better characterize the spatial variability in sound production within a site, and to compare that variability between sites.

Max recovering a lift bag at the surface (Photo: S. Zacarias)
After an overnight data download, the recorders were redeployed this morning at a site with intermediate coral cover. They will be recovered tomorrow and then redeployed the following day at our site with the least coral cover. In the meantime, we've been working on getting our long-term moorings ready for their 4-month deployment. This afternoon's quick trip back to the hardware store means that we now have (hopefully) all that we need to make sure our instruments are secure for their long underwater deployment.

Aran with two recorders during our redeployment this morning (Photo: M. Kaplan)
A typical reefscape encountered during our visual surveys (Photo: M Kaplan)
In addition to instrument deployment we've been carrying out visual surveys of the benthic cover and fish diversity over the last few days, in order to better characterize our sites. These surveys involve line transects, video and photography, and allow us to take a closer look at what species live on the reef and how abundant they are.

A visual representation of some fish grunts recorded during our first deployment. 

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