Sensor Development for Monitoring Biofilm Production and Accumulation using Underwater Imaging in Nearshore Waters

Abstract

The presence of eelgrass in the nearshore environment can be used as a proxy for the amount of ecosystem health due to its quick response to the ever changing properties of water quality, benthic condition, and physical forcing. A key ecological service provided by eelgrass is the accumulation of biofilm as a food source for marine organisms. Biofilm is a functional community of microbes embedded in an organic polymer matrix, adhering to a surface. Biofilm has three basic components which include microbes, glycocalyx and a substrate. Biofilm growth is limited by the availability of nutrients in the immediate environment, the perfusion of those nutrients to the cells within the biofilm and the removal of waste. Not only is identifying the amount of growth and accumulation of biofilm on eelgrass ecologically important, understanding biofilm accumulation can also assist in improving the functionality and performance of underwater sensors. The development of an in-situ sensor to assess biofilm production and accumulation on a variety of surface materials that may act as proxies of eelgrass structure for the purpose of quantifying ‘slime’ accumulation is presented. The aim of this research and development project is to asses a non-destructive method for the selection of construction materials used to simulate in-situ slime accumulation on eelgrass in the nearshore. While this work is conducted in the low energy nearshore environment of existing eelgrass beds in Puget Sound, Washington, the proposed method provides an approach which returns optimum material selections for other nearshore settings. In addition to monitoring the accumulation of biofilm, the in-situ sensor also monitors changes in environmental conditions which influence the production of ‘slime’. This work provides nearshore scientists and managers a cost-efficient alternative to the design and implementation of monitoring tools for the growth of biofilm accumulation in nearshore environments with potential application as a key component to those interested in monitoring programs during shoreline restoration projects