Noise in the Sea and Its Impacts on Marine Organisms

Italy introduces pre and post operation monitoring phases for offshore seismic exploration activities

Concern is growing that marine fauna can be affected by noise such as naval sonar, pile driving or geophysical surveys, among others. Literature reports a variety of animal reactions to human noise (from apparently null or negligible to strong). However, conclusive results on its effects on marine mammals at individual and population level are still lacking. In 2015, the Italian Environmental Impact Assessment Commission mandated seismic operators apply a standard scientific protocol comparing marine mammal presence before, during, and after offshore seismic survey. For 60days before and after the survey, marine mammals are monitored using visual and acoustic methods. One or more acoustic autonomous recorders, depending on area size, must also be deployed throughout the three phases for continuous monitoring. Consistent data gathered from many surveys will enable robust statistical analysis of results. Diffusion of this monitoring method internationally would improve the study of far-reaching, intense, low frequency noise.

Effects of anthropogenic sound on digging behavior, metabolism, Ca(2+)/Mg(2+) ATPase activity, and metabolism-related gene expression of the bivalve Sinonovacula constricta

Anthropogenic sound has increased significantly in the past decade. However, only a few studies to date have investigated its effects on marine bivalves, with little known about the underlying physiological and molecular mechanisms. In the present study, the effects of different types, frequencies, and intensities of anthropogenic sounds on the digging behavior of razor clams (Sinonovacula constricta) were investigated. The results showed that variations in sound intensity induced deeper digging. Furthermore, anthropogenic sound exposure led to an alteration in the O:N ratios and the expression of ten metabolism-related genes from the glycolysis, fatty acid biosynthesis, tryptophan metabolism, and Tricarboxylic Acid Cycle (TCA cycle) pathways. Expression of all genes under investigation was induced upon exposure to anthropogenic sound at ~80 dB re 1 μPa and repressed at ~100 dB re 1 μPa sound. In addition, the activity of Ca²⁺/Mg²⁺-ATPase in the feet tissues, which is directly related to muscular contraction and subsequently to digging behavior, was also found to be affected by anthropogenic sound intensity. The findings suggest that sound may be perceived by bivalves as changes in the water particle motion and lead to the subsequent reactions detected in razor clams.