A cost-effective technique for measuring relative water movement for studies of benthic organisms

Abstract

Because water movement has been shown to affect the structure and community composition of the marine environment, the ability to monitor and record water movement is important in marine research. The present study describes a cost-effective, repeatable method for measuring relative water movement both spatially and temporally with an ‘off the shelf’ accelerometer. The technique involves suspending the accelerometer in the water column near the seafloor; movement of the apparatus by the water column is recorded as changes in acceleration relative to Earth’s gravity. Water movement recorded by this technique was highly correlated (r2 = 0.822, P < 0.01) with measurements from a recognised commercial device (wave-rider buoy). Deployment tests revealed that total wave height showed the most significant relationship (r2 = 0.83) with data from the technique. Use of the technique in a field situation allowed the detection of small-scale water-movement patterns within the Houtman Abrolhos Islands off Western Australia, and the quantification of the relative differences in water movement among coral-monitoring sites. Overall, the technique is a cost-effective way of obtaining basic long-term temporal water-movement data at small spatial scales (less than hundreds of metres).