Giant clams as open-source, scalable reef environmental biomonitors

Area of Science:

• Marine Biology
• Biomonitoring
• Environmental Science

Background:

• Valvometry, measuring bivalve shell movements, is a proven biomonitoring tool for ecological studies.
• Existing valvometric methods are not readily applicable to coral reef environments, hindering research on reef resilience.
• Giant clams (Tridacna derasa) are ideal candidates for valvometry due to their coral reef habitat and sensitivity to environmental changes.

Purpose of the Study:

• To develop and test an accessible, open-source valvometry system for monitoring giant clam behavior.
• To investigate the relationship between giant clam valve activity and environmental variables in a simulated reef setting.
• To assess the potential of giant clams as bio-indicators for coral reef health.

Main Methods:

• An open-source valvometry system using off-the-shelf components was deployed on smooth giant clams (Tridacna derasa).
• The system recorded valve opening and closing behavior in the Biosphere 2 Ocean simulated reef environment.
• Data analysis focused on correlating valvometric patterns with light availability, pH, and chlorophyll-a levels.

Main Results:

• Valvometric data confirmed diurnal behavior patterns, with clams opening valves during daylight for photosynthesis and partially closing at night.
• Increased valve closure frequency correlated significantly with pH and showed a lagged relationship with chlorophyll-a.
• These findings suggest giant clams adjust feeding and behavior in response to light, pH, and phytoplankton availability.

Conclusions:

• The developed open-source valvometry system is effective for monitoring giant clam behavior and environmental interactions.
• Giant clams exhibit behavioral plasticity, responding to environmental cues relevant to ocean warming and acidification.
• Widespread adoption of this accessible valvometry technique can facilitate comparative studies of coral reef health and resilience.