Lethal and sublethal implications of low temperature exposure for three intertidal predators.

Area of Science:

• Marine ecology
• Intertidal zone biology
• Invertebrate physiology

Background:

• Intertidal predators regulate ecosystems, but winter cold stress effects are understudied.
• Summer heat stress on these predators is well-researched, unlike winter cold.
• Understanding winter impacts is crucial for intertidal ecosystem health.

Purpose of the Study:

• To investigate the effects of winter cold exposure on key intertidal predators.
• To assess supercooling points, survival, and feeding rates of sea stars and dogwhelks.
• To examine microhabitat use and body temperature variation during winter low tides.

Main Methods:

• Measured supercooling points and survival of Pisaster ochraceus, Evasterias troschelii, and Nucella lamellosa after cold exposure.
• Assessed feeding rates following sublethal cold stress.
• Quantified predator body temperatures across different microhabitats during winter low tides.

Main Results:

• Predators showed internal freezing at mild sub-zero temperatures (sea stars: -2.5°C, dogwhelks: -3.99°C).
• Survival rates were moderate-to-low after exposure to -8°C.
• Feeding rates significantly decreased for two weeks post-exposure to -0.5°C.

Conclusions:

• Intertidal predators have limited freeze tolerance, making them vulnerable to winter conditions.
• Reduced feeding and survival can alter predator-prey dynamics in intertidal zones.
• Habitat microclimate influences predator body temperature, but behavioral thermoregulation was not observed.