Does temporal variability limit standardized biological monitoring at wave and tidal energy sites?
Keywords:biological monitoring, fish, marine renewable energy, stationary acoustics
Commercial viability of Marine Renewable Energy (MRE) is progressing but no national or international monitoring standards have been established for wave or tidal energy sites. Standardized monitoring within and across MRE sectors is necessary to expedite project permitting/consenting, detect environmental impacts, and enable comparison among sites and technologies. Acoustic backscatter from a bottom-deployed platform at a pilot wave energy site off Newport, Oregon was compared to data collected at a tidal turbine site in Admiralty Inlet, Washington. Metrics that describe fish and macrozooplankton densities and vertical distributions derived from acoustic backscattered energy were compared using wavelets and Autoregressive Moving Average models (ARMA). Average density and vertical distribution values significantly differed between sites. Metrics of density and location in the water column displayed diel (24 h) and tidal (12 h) cycles. Dispersion of animals in the water column varied at 64- and 128-h periods at both sites. Applicability of methods in both sectors suggests that a standard approach to biological monitoring is possible. Stationary acoustics and analytic methods presented here can be used to characterize pre-installation conditions and refine post-installation monitoring to site-specific characteristics to ensure cost-effective detection of impacts associated with MRE development.
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