Skip to main content
2023 ESA Annual Meeting Main banner
Icon Legend
This session is not in your schedule.
This session is in your schedule. Click again to remove it.
Back

Contributed Talk

Session: : Restoration Ecology 10

COS 223-6 - Scared strong: Using predator chemical cues to enhance oyster survivorship at the restoration scale

Wednesday, August 9, 2023
4:45 PM – 5:00 PM PDT
Location: E145
Abstract: Many prey species can adjust morphology to reduce predation risk in response to predator cues. Using predator cues to enhance prey defenses may improve survival of cultivated species and enhance species restoration efforts, but assessment of such benefits across industrially relevant scales and identification of these chemical cues is needed. We examined how raising a model foundation species, oysters, under commercial hatchery conditions with cues from a common predator species can improve survival in the field and reef restoration success. In partnership with the Mississippi Department of Marine Resources, we twice settled 12 million oyster larvae on nine tons of oyster shell as “spat-on-shell” in multi-tank saltwater flow-through systems. Half the spat were exposed to caged blue crabs to release predator cues while the other half received no predator cues as a control. After one month of these nursery conditions, spat were planted in the field to produce two reefs where survivorship was assessed periodically for three months. Concurrently, we ran bioassays to identify the chemical cues predators release that stimulate oysters to grow stronger shells. We placed recently settled oysters into jars and exposed them to eight different concentrations of urine extracted from blue crabs as well as candidate molecules for inducing defenses. Oysters were held under these conditions for two months before measuring individual growth and shell strength. Oyster shell strength increased by 20 – 100% when exposed to predator cues in the hatchery system and followed a standard dose response curve with crab urine concentration causing shell strength to peak at ~0.19 mL urine/L seawater. Additionally, induced oysters had 73% higher survivorship than controls after being in the field after one month, although survivorship differences varied substantially depending on the time period and site. These findings demonstrate the utility of using predator cues to enhance the survival of target species, and highlight an opportunity to employ nontoxic methods to control pest-based mortality.