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

Simple Summary: We exposed two invertebrates to hydrogen peroxide to mimic some of the conditions that occur before large earthquakes. Water fleas changed their position in an aquarium to avoid the hydrogen peroxide but earthworms appeared not to be affected and did not change position. We discuss this in the context of unusual animal behavior often seen before earthquakes. Abstract: 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.