Sustainability of Reef Fishes and Causes of Harmful Algal Blooms

Micro-ROV dives at the Liberty Ships site

Dr. Stacey D. Lyle, Texas A&M University Corpus Christi
Oct. 13 2012

Today, the Fisheries group at the Harte Research Institute (TAMU-CC) deployed their micro remote operated vehicle (ROV) at the Liberty Ships reef site MU-802. The Fisheries group normally uses their micro ROV for fish surveys at their artificial reef sites along south Texas. However, given the presence of a working-class ROV on the R/V Falkor, and a team of professional crew and pilots to drive and maintain this 3D capable unit, the micro ROV was brought aboard only as a backup unit. Due to a slight communication issue between the ship and the “macro” ROV, it was time for the micro ROV to “strut its stuff” and keep the surveys ongoing during this temporary timeout.

The goal of the micro ROV mission was to test the ability of the team to find the Liberty Ships from a dynamically positioned R/V Falkor. During dynamic positioning (DP), the ship automatically maintains its position over a small area by strategically situating itself againts the wind and current and making minor adjustments with the propellers and bow thrusters to stick to the spot. Because the team had precise multi-beam data from mapping the Liberty Ships on the previous night, the captain was able to position R/V Falkor a very short distance away from the reef site. Then, using careful coordination and communication with the captain, the Fisheries group methodically approached the site with the micro ROV and successfully located the southernmost Liberty ship of the reefing area. This was completed without the use of sonar, which is no easy feat in murky conditions!

The surface of the ship was located at approximately 30 meters (100 ft) and immediately revealed an abundance of snappers, triggerfish and angelfish. While slowly roving the Liberty ship’s deck, the team was able to locate a variety of hatches where ammunition was previously stored on these transcontinental World War II Ships. To the delight of the scientists, the micro ROV returned to the R/V  Falkor with nearly an hour of high-definition footage of the site, including information on the temperature profile between surface and bottom waters of the artificial reef and laser-derived size estimates for a host of fish species.

Now that Dr. Greg Stunz and Dr. Matt Ajemian have high-quality and recent georeferenced images of the Liberty Ships generated from the cruise, they can return to this site and use their micro ROV to repeat these transects over time. The successful ROV mission demonstrated the ability of the scientists and ship’s crew to work together and keep operations “afloat” even when technical issues arise.

-Written by Drs. Stacey D. Lyle and Matt Ajemian for Schmidt Ocean Institute

Video from the test Deployment of Texas A&M University-Corpus Christi micro-ROV at Liberty Ships artificial reef from Schmidt Ocean Institute research vessel Falkor on October 12, 2012.  Video credit: Dr. Stacey D. Lyle at Texas A&M University-Corpus Christi

Schmidt Ocean Institute marine technician Nathan Cunningham discussed his work onboard research vessel Falkor on October 12, 2012.  Video credit: Dr. Stacey D. Lyle at Texas A&M University-Corpus Christi

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Texas A&M University- Corpus Christi Expedition Blog

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