Diving into the Details of Underwater Surveying

By Tatum Updegraff
​From May 17, 2018
During the span of the USF course, Tropical Marine Ecology and Conservation, students participating in the program have had to show adequate diving skills tailored for scientific research. Underwater surveying has been the largest skill set that’s been taught, and includes benthic point intercept surveys, fish surveys, and photo transects.

​Benthic point intercept surveys are performed over three 30m transects that are laid end-to-end at a depth of 15m and require one buddy team to start at transect one. One partner documents the distance from 0m-5m and the other does 5m-10m. At 10cm intervals, whatever is under the transect tape is recorded. The point intercept aspect of the survey helps discourage bias from impinging on the collected data. The procedure is then repeated for the remaining two transects. Post-dive, data analysis is performed, which requires the data to be input to an excel file where the percent coverages are calculated for coral, macroalgae, filamentous cyanobacteria, substrates, dead coral covered in algae, sponges, and crustose coralline algae. This data is later compiled into a pooled average of all the benthic surveys taken throughout the duration of the course and is used to draw conclusions about the effectiveness of marine protected areas and how sedimentation affects reef organisms.

Fish surveys are conducted simultaneously with the point intercept surveys along the same three 30m transects. Two buddy pairs are required to cover the length of the transects. One pair of divers starts at transect one and the other at transect three. Each diver is then responsible for surveying a cylinder with a 5m radius in which the diver records on a slate any fish species that swim through that designated area along with their approximate size. The data is then analyzed to give an idea of which species are more prevalent at certain sites.

As fish surveys and benthic point intercept surveys are being completed, photos are also being taken every other meter as part of a photo transect.  Four photos are taken 75cm above the bottom to make up a full meter squared. These photos are later input to a program called Coral Point Count with excel (CPCe) that overlays twenty random points on each picture. The points are then identified as species of coral, organism, macroalgae, or substrate, which then gives an idea of an unbiased percentage of benthic coverage.

Being able to participate in such an enriching program has been an incredible experience that I would highly recommend to anyone that is even remotely interested in marine science or field work. The skills that I’ve been taught on this trip are invaluable and have helped to prepare me for many future projects that pertain to my career path and overall has been a fun time. So, thanks to those of you who read the blog and have kept up with our journey. Until next time, go Bulls.