Hardening in oysters drives increased growth

It’s a stage specific thing

March 8, 2024

In the meticulously orchestrated world of marine science, a groundbreaking experiment has unfolded in the hands of Eric Essington, casting the spotlight on an unlikely protagonist: the oyster. This narrative begins with the arrival of 235 adult oysters from Pacific Hybreed, their sizes ranging impressively from 40 to 100mm, and further complemented by a diverse younger contingent—120 juveniles, 120 seed, and approximately 120 spat, all courtesy of the USDA’s 2023 spawn.

The experimental setup divided these oysters into two groups: one destined for a control tank, mirroring their natural aquatic environment at a serene 17ºC, and the other for a treatment tank, where conditions were significantly altered. The latter group was subjected to a deliberate increase in temperature, a gradual ascent of 2ºC per hour until the water reached a stress-inducing 26ºC, maintained for six hours daily over a seven-week span (began 10 2 2023, ended 11 21 2023). This thermal regimen aimed to simulate the increasingly erratic and harsh conditions wrought by climate change.

Adding a layer of complexity, adults and juveniles were subjected to mechanical stress, an innovative use of a salad spinner for 15 minutes on selected dates (10/2/2023, 10/4/2023, 10/11/2023). This unusual methodology aimed to mimic the physical disturbances oysters might face in their natural habitats, from tumbling in currents to encounters with predators and debris.

The culmination of this phase was marked by a meticulous sampling process on November 21, 2023. Selected groups of oysters were divided for detailed analysis, with some undergoing immediate tissue sampling for RNA and DNA analysis, while others faced an additional stress test—a 30-minute immersion in 32ºC water followed by a tumbling session in the salad spinner. This process was designed to simulate an acute stress event, allowing researchers to gauge the oysters’ physiological responses to compounded stressors.

Several months later, on February 28, 2024, the experiment was revisited with a focused approach. This time, the younger generation of oysters was spotlighted, undergoing tissue sampling without the prior mechanical stress, to isolate the effects of thermal stress.

Take-away to date - Stress hardening in spat in October and November resulted in increased growth compared to controls in February.

This experiment is not merely an investigation into the resilience of oysters to thermal and mechanical stress; it’s a narrative about adaptation, survival, and the intricate dance of life beneath the waves.

See Eric’s Post for more details.