Central/South American Convergent Margins: Biology Meets Subduction

This project draws together biologists, geochemists, petrologists, and outreach professionals to take a regional view of the deep subsurface biosphere across a convergent margin. The Costa Rica convergent margin is caused by the oceanic Cocos plate being subducted under the Caribbean plate. As the plate is subducted, dewatering due to compression and serpentinization reactions between water and rock drive nutrient rich hot springs whose surface expression reflects the deep processes that feed it. We are taking a multi-disciplinary approach to connecting these surface expressions to the deep subsurface biosphere. We work with collaborator Maarten de Moor and colleagues at OVSICORI. We are finding that chemolithoautotrophic subsurface ecosystems contribute to the sequestration of carbon emanating from the deeply-buried tectonic plate below them. More recently, we have extended this work to sample actively-venting fluids along the volcanic arc backarc of the Andean Convergent Margin in Argentina (collaborating with Agostina Chiodi and colleagues at IBIGEO) and the forearc and volcanic arc of the Andean Convergent Margin in Chile (collaborating with Gerdhard Jessen and colleagues at Universidad Austral de Chile and Jenny Blamey at the Fundacion Biociencia). This is also a collaboration with Peter Barry (WHOI), Donato Giovannelli (U. Naples, Italy), and Matt Schrenk (Michigan State U.).

Left: Logo from Biology Meets Subduction (by Josh Wood). Right: Logo from Chile field trip 2020 (by Patricia Barcala Dominguez).

We sampled Poás volcano crator lake in February 2017. Photo by Tom Owens. Check out the current eruption status of Poás here.

Puna volcanic back arc in Argentina. Photo by Karen Lloyd.

Hot spring sampling in Argentina 2019. Photo by Peter Barry.

Current PhD student TJ Rogers sampling hot springs in Chile 2020. Photo by Karen Lloyd.

Deep oceanic subsurface

We are working on the IODP Leg 347: Baltic Sea Paleoenvironment and IODP Leg 366: Mariana Convergent Margin and South Chamorro Seamount. Here, we analyze deep subsurface microbial communities buried in up to 86 meters beneath the seafloor into either pelagic sediments (Leg 347) or serpentinizing mud volcanoes (Leg 366). This work is largely a collaboration with Brandi Reese at Dauphin Island Sea Lab.

Left: Former PhD student, Richard Kevorkian, processing a deep subsurface core aboard the Joides Resolution in IODP Leg 366: Mariana Convergent Margin and South Chamorro Seamount. Right: Greatship Manisha outfitted for the Leg 347 expedition to the Baltic Sea.

Arctic fjords and permafrost in Svalbard

The effects of climate change are exacerbated in polar regions. We are examining feedbacks between the novel, uncultured microorganisms and marine sediments at the foot of the receding glaciers in marine fjords in Ny Alesund, Svalbard, 79°N. For this, we work with the AWIPEV Arctic Research Base. We are starting a new project drilling into permafrost to study how subsurface microbes handle potential greenhouse emmissions as the perfmafrost thaws from climate change, in collaboration with Tatiana Vishnivetskaya (Center for Environmental Biotechnology UTK), Andrew Steen (UTK), TC Onstott (Princeton U.), Robert Hettich (ORNL), and John Cliff (PNNL) working with the UK Arctic Research Station.

Former PhD student Joy Buongiorno and current PhD student Katie Sipes in Ny Alesund, Svalbard, 79°N.

Former PhD student Joy Buongiorno sampling sediments in Kongsfjorden, Svalbard.

Glacier in Kongsfjorden, Svalbard.

Siberian permafrost

Long-term frozen permafrosts present a unique situation to study microbes that have been preserved in time, or are growing very slowly in small saline pockets of liquid water. We are on a project headed by Tatiana Vishnivetskaya (see above for contact info) to examine such permafrosts in Siberia. See videos from that project under the outreach tab.

Low Energy Methanogens

Methane-producing archaea (methanogens) are responsible for almost all of the methane on Earth. Although natural methanogens often operate under severely nutrient limited conditions, most of what is known about methanogen physiology comes being grown under high energy conditions. When grown at low substrate concentrations, methanogens are one of the lowest energy life forms on Earth, hence they are of interest in astrobiology. We are studying natural methanogens from the White Oak River estuary and Cape Lookout Bight, both in North Carolina, to determine the properties of low energy methanogens. These will provide key constraints in the search for extraterrestrial microbial life, which, if present, is likely to include methanogens.


Undergraduate students Taylor Pickett, Talor Noordhoek, and Jacob Rosalsky sampling estuarine mud to search for low energy methanogens in the White Oak River estuary, North Carolina

Deep-Sea Aerobic Methanotrophs

We have a new collaboration with Christopher S. Martens at the University of North Carolina to study deep-sea aerobic methanotrophic communities stimulated by natural releases of methane at the seafloor offshore North Carolina and in the Gulf of Mexico. These organisms ma buffer against geological and industrial releases of the greenhouse gas methane to the atmosphere.

© Karen Lloyd 2020