In partial fulfillment of the requirements for the degree of

Master of Science in Biology

in the

School of Biological Sciences

Mary McWhirt

Will defend her thesis

“Microbiome Variation in Wild vs. Captive Eagle Rays (Aetobatus narinari)”

Thursday, July 18, 2019

1:00 PM

Ford ES&T L1118

Thesis Advisor:

Dr. Frank J Stewart

School of Biological Sciences

Georgia Institute of Technology

Committee Members:

Dr. Lisa Hoopes

Director of Research, Conservation and Nutrition

Georgia Aquarium

Dr. Brian Hammer

School of Biological Sciences

Georgia Institute of Technology

Abstract:

The microbial communities (microbiomes) associated with elasmobranchs are currently not well-understood. The spotted eagle ray (Aetobatus narinari) is a slow-maturing ray that is globally distributed in tropical and warm-temperate waters, and is listed as near-threatened by the IUCN Red List. To test how the environment shapes the spotted eagle ray microbiome, we used 16S rRNA Illumina sequencing to compare the microbiomes of the dorsal skin, gill, and cloaca from a ray population near Mote Marine Lab (Sarasota, FL) to those from a captive population in the Ocean Voyager exhibit at Georgia Aquarium, while also analyzing water column microbiomes from both environments. Cloaca microbiomes of both populations had the lowest alpha diversity and highest beta diversity, potentially indicating the presence of transient microbes associated with changes in diet between the environments. The composition of the gill and skin microbiomes differed between captive and wild populations and are similar to, but distinct from, the water column communities while cloaca microbiomes are more dispersed from the water. This pattern is consistent with that seen in teleost fishes and marine mammals. These results indicate a dual role for body niche and environmental conditions in shaping ray microbiomes and identify key taxa that may be important to the health of the rays.