Throughout the month of July, researchers with NOAA’s National Centers for Coastal Ocean Science (NCCOS) and NOAA’s Office of Response and Restoration engaged in a joint preparedness exercise in coastal Louisiana, testing newly developed field-based mesocosms — simulated environments within caged enclosures — for potential use in natural resource damage assessments (NRDA) of nearshore marsh ecosystems. Scientists use mesocosms (Photo 1) to study the effects of various elements, such as oil and chemicals, on habitat and organisms. 

Photo 1: Securing the lid on a mesocosm cage after loading test organisms for the 20-day deployment. Credit: NOAA.

For this event, the team deployed 12 mesocosm cages at two sites in the Little Lake area of Louisiana’s Pearl River bayou. The team collected local killifish and shrimp that they released into the mesocosms for a 20-day mock exposure period. Throughout the exposure period, the team tested the use of visible implant elastomer tags — individual implant devices (Photo 2) — which enabled them to track and assess individual survivorship and growth rate throughout the study period. To test the water quality surrounding the mesocosms, the team deployed passive sampler silicone bands and water quality samplers to monitor for chemical contaminants, and water quality sondes — probes that continuously monitor environmental conditions such as water temperature, salinity, dissolved oxygen, and pH. The team used the NOAA-Mississippi State University Northern Gulf Institute facility at the Stennis Space Center to stage the gear and equipment and for the project’s laboratory component, which involved tagging the live animals and measuring and weighing them before and after the deployment. 

The team was joined in the field by co-trustees from the Louisiana Department of Environmental Quality and Louisiana Oil Spill Coordinator’s Office so they could learn about this process and how it could be applied to NRDA case work in Louisiana. 

This study represented the first full-scale deployment of the systems at a remote site by boat. Ultimately, the purpose of the mesocosms is to assess in situ effects during oil or chemical spills in estuarine areas of the Southeastern U.S. and Gulf of Mexico in support of a Natural Resource Damage Assessment. This pilot exercise enabled the team to assess logistical challenges and to further refine methodologies.

Visit the project page to learn more about using mesocosms to assess the impacts of chemical spills. Explore this storymap to see how the team constructs and prepares mesocosms for deployment.

Photo 2 (left): Measuring total length of a killifish tagged with a Visible Implant Elastomer tag (note red markings near dorsal and caudal fins). Photo 3 (right): Submerged mesocosm cages at a deployment site along marsh edge in the Pearl River area, Louisiana. Credit: NOAA.