Award: OCE-1851421

Deep-sea methane seeps are fascinating because they support entire ecosystems that thrive without sunlight. Instead of photosynthesis, life at these sites is fueled by methane and other chemicals rising from the seafloor. Giant tube worms, mussels, shrimp, clams, and white bacterial mats form complex communities, with methane-feeding microbes forming the base of the food web.

This National Science Foundation funded study used advanced deep-sea vehicles—Alvin (a human-occupied submersible), Jason (a remotely operated vehicle), and Sentry (an autonomous underwater vehicle)—to deploy instruments that measure deep-sea currents and to collect organisms such as mussels. In terms of Physical Oceanography, observations were used to validate high-resolution ocean model simulations that can also assimilate regional observations from satellites, moorings, glider/ship surveys to help predict deep sea currents and larval dispersal among seep sites, as well as better understand extreme events such as deep-sea heat waves that can negatively impact these ecosystems. In terms of Biological Oceanography, mussels form growth rings in their shells like tree rings. These rings, along with chemical signatures preserved in the shells from different stages of the mussels’ lives, provide clues about how fast they grew, when larvae were released, and the water conditions they experienced as they drifted and eventually settled on the seafloor. For example, the water mass chemical signatures in the shells of mussels differed significantly among depths, sampling years, and sites, which were largely distinguished by the chemical elements barium, nickel, and manganese ratios, possibly reflecting depth-related food sources such as phytoplankton. The chemical signatures in shells also varied among growth regions on the shells of deep-sea mussels in a manner that suggested larvae are more mixed during early dispersal than later in their dispersal. 

By combining shell chemistry, information about water masses, and computer models of deep-sea currents, scientists can better understand how larvae travel between seep sites and which areas supply new generations to others. This knowledge helps guide conservation efforts and deepens our understanding of these remarkable and fragile deep-sea ecosystems.

Last Modified: 02/17/2026
Modified by: David B Eggleston