Behavioral Response of Invertebrates to Experimental Simulation of Pre-Seismic Chemical Changes

Unusual behavior before earthquakes has been reported for millennia but no plausible mechanism has been identified. One possible way in which animals could be affected by pre-earthquake processes is via stress activated positive holes leading to the formation of hydrogen peroxide at the rock water interface. Aquatic and fossorial animals could be irritated by H₂O₂ and move down the concentration gradient. Here, we carry out avoidance tests with hydrogen peroxide in two model organisms; Daphnia pulex and earthworms. Daphnia were found to move away from increasing concentrations of H₂O2 but earthworms appeared unaffected. It is possible that earthworm swarming behavior, reported frequently before earthquakes, is caused by electric field shifts or another unknown mechanism, whereas zooplankton may be affected by increasing levels of H₂O₂.