The authors explain and describe the mutually rewarding insights that resulted from the interdisciplinary collaboration between an environmental study group working coastal ecosystems and effects of oil spills and applied mathematicians modelling wave motion on sandy beaches. By using the unified Navier-Stokes equations with a Bingham fluid model for spilled oil, multi-phase flow analysis were made. Decomposition of spilled oil by bacteria was simulated as a chemical reaction, and the theoretical and numerical analysis suggested a countermeasure to help reduce stress on coastal ecosystems....