Seafloor and Community Characterization on Low Temperature Ridge Flank Hydrothermal Systems

Anne M. Hartwell
Ph.D. Dissertation Proposal Defense
Thursday, Jun. 17, 2021, 10:00am

Life in the deep-sea is largely unexplored, in-part due to challenges of deep-sea exploration that limit the availability of data. Developing informed management plans for deep-sea communities and modeling their responses to environmental change requires mapping species distribution, biodiversity, and understanding biological relationships with their environment. In 2013, the discovery and exploration of Dorado outcrop, a discharge outcrop on a Ridge Flank Hydrothermal Systems (RFHS), yielded an unprecedented volume of observations and coverage of the seabed (3 km). A second RFHS was found within the Davidson Seamount Management Zone National Marine Sanctuary (DSMZ-NMS). RFHS ecosystems are unique as they contain both ambient cold bottom water and high-temperature venting systems. Fluid discharge from RFHS outcrops is warmer (+10°C) than ambient bottom water but is absent of chemical alteration (with the exception of dissolved oxygen) and results in the occurrence of warm pockets at points of discharge. High resolution multibeam surveys that enable fine-scale characterization of the geomorphology, temperature, dissolved oxygen and thousands of images were collected at both locations. Annie's dissertation focuses on comparing environmental variables and benthic community composition between vent and non-vent zones on Dorado and in the DSMZ-NMS, characterizing the geomorphology of RFHS at local and regional scales, and creating a habitat suitability model for identified species to assess the impacts of future environmental conditions on the current RFHS communities, as well as exploring the applicability of habitat suitability models to predict the occurrence of other RFHS based on geomorphology and heat flow. This study presents a rare exploratory opportunity to characterize the geology and biology of deep-sea species associated with geothermally unique outcrops. This will expand our knowledge of deep-sea biodiversity, improve our ability to model and interpret the impacts of climate change, and predict the occurrence of additional similar systems.


Annie is a 2010 graduate of the University of New Hampshire, where she obtained an B.S. in Geology. She earned a Master of Science in Oceanography at the University of Rhode Island Graduate School of Oceanography in 2013. Her master's project focused on interpreting global marine nitrogen cycling during the Last Glacial Maximum from a set of un-reacted pore fluids collected below the North Pacific Gyre.

After graduating, Annie held a position as a research associate in a geochemistry lab at the University of Akron, an opportunity that afforded her the chance to dive 1.5 miles below the sea surface in HOV ALVIN.  Following her position as a research associate, Annie remained at the University of Akron as a visiting scholar, and split her time as a remote researcher for the University of Alaska Fairbanks and as an adjunct faculty member at Cuyahoga Community College. After leaving Ohio in spring of 2016, Annie continued to work remotely for UAF and, in fall of 2017, she held a short term position as a Research Associate at Bigelow Laboratory for Ocean Sciences. In addition to Annie’s work as a marine geochemist, she takes a deep interest in deep-sea exploration. In 2018, she published a paper investigating the largest and deepest cluster of brooding octopods ever observed and their ill-fated future.

Annie is currently pursuing a Ph.D. in Oceanography. Her research will focus on habitat mapping. Ultimately, Annie is interested in the connection between the biosphere and the environment. For instance, understanding the macro-community members and distribution, and investigating what roll the environmental factors (geological, chemical, physical, thermal) have on them. In additional to scientific research, Annie enjoys scientific outreach and has been a contributing blog writer to since 2013.