National Geographic

VOICES Voices Icon Ideas and Insight From Explorers

Menu

Analyzing Seagrass Beds in the Bahamas: Diving into Field Research with Shedd Aquarium

A small conchfish inside a queen conch
Queen conch (Strombus gigas) and Conchfish (Astrapogon stellatus). Image credit: Shedd Aquarium / Keith Pamper.

The second installment in a series of posts by Chicago area college students enrolled in the John G. Shedd Aquarium’s Marine and Island Ecology course offered through the Associated Colleges of the Chicago Area (ACCA). Our students work closely with Shedd staff through both field work and onsite classes. At the end of the course, students fly into Nassau to live aboard Shedd’s 80-foot research vessel, the R/V Coral Reef II, in the Exuma Islands, Bahamas. Click here for the first story.

My name is Elise Raz, and I am a junior at Aurora University majoring in Biology and Secondary Education. My dream career is to teach high school Biology and Ecology through hands-on problem based learning. When Shedd Aquarium offered me the opportunity to study ecology, research, and conservation practices, I simply could not pass it up.

During our time onboard the Coral Reef II, our class worked with several instructors, including Shedd’s Postdoctoral Research Associate, Dr. Alexander Tewfik. He investigates how overfishing of Queen conch (Strombus gigas) and spiny lobster (Panulirus argus) impact ecosystems in the Bahamas. As part of his work, Dr. Tewfik is assessing the quality of seagrass beds in the coastal marine environment of the Bahamas with respect to the impacts on conch

A woman dives to the seagrass bed with the core sampler
Erin dives to take a core sample. Image credit: Shedd Aquarium / Alex Tewfik.

During our trip, Dr. Tewfik gave us a hands-on introduction to marine research by designing an activity that allowed us to collect data from seagrass beds using some of the same methods that he uses. We were split into groups and were assigned to measure depth and percent of seagrass coverage every 10 meters off the beach at Shroud Cay in the Exuma Islands. We were given PVC quadrants (50 by 50 cm squares) to conduct our measurements. We took six measurements to assess plant cover through visual estimates while also recording any invertebrates we saw along the entire transect. We also took bottom core samples every 20 meters to directly measure the biomass of seagrass above and below the sandy floor.

Taking these observations and measurements in the Exumas gave me a whole new respect for field researchers. Estimating percent coverage may sound self-explanatory, but in practice it is much more difficult to do consistently. My group of 3 students had very different perspectives about the percentage of seagrass cover that we observed: In one quadrant, our estimates ranged from 25 to 60 percent. We had to go back and review photos that showed what different coverage would look like as a standard for our measurements.

Two women in dive gear stand in chest-deep water with research equipment.
Alexis Gramera (left) and Elise Raz, college students in Shedd Aquarium’s Marine and Island Ecology course, bag core samples of seagrass beds in the Bahamas. Image credit: Shedd Aquarium / Alex Tewfik.

Extracting core samples from the seagrass bed was no walk in the park, either. We were given a coring device to push into the sediment at least 10cm, extracting a representative sample of seagrass shoots and root structure. This was not so difficult in the shallower areas closer to the shore, where we could easily stand and place pressure down on the device. However, when it came to taking samples more than 1 meter below the surface, extraction became a much more difficult task and required a few dives down to complete.

We may have looked ridiculous to the other boats, but it was fun and well worth it in the name of science. Overall, I have come to the conclusion that researchers require much more than the ability to crunch numbers in a lab. My experience with Shedd on board the Coral Reef II gave me a whole new appreciation for conservation field research.

In partnership with the Bahamas National Trust and Bahamas Department of Marine Resources, Shedd Aquarium, led by Dr. Tewfik, has embarked on a three-year research program to conduct assessments of exploited Queen conch and spiny lobster populations in the context of important seagrass and coral ecosystems respectively. 

A diver holds a spiny lobster
Students get up-close with a spiny lobster, the largest fishery in the Bahamas and the fourth largest lobster fishery in the world. Image credit: Shedd Aquarium / David Wagner.

Comments

  1. Don Ale Mar Llego
    murcia
    July 31, 2013, 4:53 am

    this article is good… please keep on posting more studies about sea grasses. i really need it in my undergraduate thesis.

    thank you