Green crab (Carcinus maenas) foraging efficiency reduced by fast flows

Area of Science:

• Marine Ecology
• Invasive Species Biology
• Behavioral Ecology
• Hydrodynamics

Background:

• Predators critically influence ecosystem structure and function.
• Environmental stressors like fluid velocity can modify predator impacts by altering foraging.
• The invasive green crab (Carcinus maenas) is globally distributed in marine habitats.

Purpose of the Study:

• To investigate how hydrodynamics affect the foraging behavior of the green crab (Carcinus maenas).
• To identify the mechanisms by which flow velocity influences green crab predation rates.
• To determine the effects of flow on prey detection, foraging efficiency, and prey handling time.

Main Methods:

• Field study using baited traps to assess crab capture rates at varying flow velocities.
• Laboratory flume assays to quantify foraging efficiency and prey handling time under controlled flow conditions.
• Experimental manipulation of flow velocity to simulate different hydrodynamic environments.

Main Results:

• Fewer green crabs were captured in baited traps at high flow velocity sites compared to slow flow sites, despite higher crab abundance in high-flow areas.
• Foraging efficiency of green crabs significantly decreased with increasing flow velocity in laboratory flume assays.
• Prey handling time for green crabs significantly increased in high-velocity flows.

Conclusions:

• Flow velocity imposes significant chemosensory and physical constraints on green crab foraging.
• Hydrodynamics play a crucial role in modulating the foraging success and ecological impact of green crabs.
• Findings suggest that altered flow regimes can influence the predator-prey dynamics in rocky intertidal communities.