Hydrodynamic sensory stressors produce nonlinear predation patterns

Area of Science:

• Ecology
• Marine Biology
• Behavioral Ecology

Background:

• Predator effects on community structure are significant but can be reduced by physical stress.
• Environmental conditions can limit predator foraging and prey detection, acting as sensory stressors.
• Traditional refuge models may overlook how environmental conditions simultaneously affect predator and prey behavior.

Purpose of the Study:

• To investigate how hydrodynamics (flow velocity and turbulence) influence predation intensity between blue crabs (Callinectes sapidus) and hard clams (Mercenaria mercenaria).
• To determine if environmental conditions that impede predator foraging also increase prey vulnerability.
• To explore the complex relationship between environmental stress, sensory perception, and predator-prey interactions in a field setting.

Main Methods:

• Field experiments manipulating turbulence in sites with varying flow velocities.
• Comparison of predation levels on hard clams by blue crabs across different hydrodynamic conditions.
• Integration of laboratory findings on sensory responses of crabs and clams to flow.

Main Results:

• Blue crabs exhibit peak foraging effectiveness at intermediate flow velocities and turbulence levels.
• These intermediate conditions, while suboptimal for blue crabs, significantly impair hard clams' ability to detect and evade predators.
• Predation rates do not necessarily decrease with increasing environmental stress when both predator and prey behaviors are affected.

Conclusions:

• Sensory stressors can create complex predator-prey dynamics, where reduced predator efficiency is offset by increased prey vulnerability.
• Environmental forces influencing predator foraging and prey avoidance can alter the balance of lethal and nonlethal predator effects in ecosystems.
• The concept of environmental refuges needs refinement to account for simultaneous impacts on sensory and behavioral processes of interacting species.