Apparent tectonic disturbance reshapes seepage and disrupts symbiotic species distributions at a Costa Rican methane seep

Chemosynthetic ecosystems experience pronounced short-term environmental fluctuations and steep abiotic gradients compared to background deep-sea environments, leading to the suggestion that chemosynthetic organisms may be more resilient to disturbance. However, the extent of this resilience and the identity of potential pioneer species remains uncertain. A magnitude 6.5 earthquake event on the Pacific Costa Rican Margin in November 2017 provided a rare opportunity to assess the effect of a natural disturbance event on symbiotic methane-seep species and associated communities. Using a spatial mapping and maximum entropy modeling approach, shifts in abiotic conditions and species distributions before and after the earthquake were evaluated. Our results reveal substantial changes in seepage activity across the Mound 12 site, including in areas inhabited by dense foundation species aggregations. Notably, vesicomyid clams exhibited strong pioneer species characteristics, appearing to have relocated across the site in response to changes in seepage signals. This study provides direct evidence of such movement in a methane-seep habitat, and offers crucial insights into the potential responses of these ecosystems to future natural and anthropogenic disturbances.