Little Ambergris

Exploring Microbial Mat Ecosystems on Little Ambergris Cay, B.W.I.

To understand the signatures of habitability on other planetary surfaces, we must also be familiar with the expression and preservation of life on Earth. Stromatolites and microbialites represent perhaps the oldest remnants of ancient life on Earth, dating back to the early Archean. The signatures of these structures observed in the rock record, as well as the environmental conditions they preserve, are best understood by studying modern analogs of these ancient systems.

One spectacular modern analog is found on an uninhabited island in the Turks and Caicos. Little Ambergris Cay is a ~6 km long, 1.6 km wide uninhabited island on the Caicos platform in the Turks and Caicos. Much of the island is covered by microbial mats, vertically stratified collections of microorganisms that respond to vertical gradients in sunlight and chemistry. Little Ambergris provides an analog for the study of microbial mat development in the sedimentary record. We use a combination of UAV- and ground-based mapping to characterize the sedimentology of biogacies across Little Ambergris and understand the factors that control their morphology. In the summer of 2016 and 2017, we quantified cm-scale variations in topography as a function of water depth by generating high resolution UAV-based orthomosaics and digital elevation models that we compared with in-situ mapping (publication forthcoming). Because of the sensitivity of the microbial mats to water depth, Little Ambergris is also an excellent site to track how the mats respond to short-scale changes brought on by drought, sea-level rise, and stochastic events like hurricanes. In September of 2017, Little Ambergris was directly hit by (in the eye of) the category 5 hurricane Irma. We have recorded the incredible response and recovery of the ecosystem in four field sessions since the hurricane to better understand the impact of large storms in similar environments (publication also forthcoming).

I am also working in collaboration with Caltech's Center for Autonomous Systems and Technologies (CAST) to develop an entirely autonomous drone and drone enclosure that will be housed on Little Ambergris Cay. The drone will be mounted with a miniaturized hyperspectral imaging spectrometer and color camera. Because Little Ambergris is uninhabited, the drone enclosure will be entirely self-sufficient, charging, calibrating, and processing and downlinking data from the drone. We previously mounted the imaging spectrometer on a DJI Matrice 600 to investigate the response of mats to environmental factors by tracking changes in their pigmentation. Some images from this are below. You can also see a video of prototype testing below.

Fieldwork was sponsored by the Agouron Institute.