A Method for Estimating Final Concentrations in Aquatic Systems that Accounts for Dilution During Sampling: A Case Study of Virus-Like-Particles Near a Coral Reef

Total concentrations in aquatic systems as a whole can be determined based on concentrations in the water sample and surrounding environment, the volume of sample, and the velocity of sample extraction. Although the model presented herein focuses on virus-like-particle (VLP) concentrations, it could be used to determine concentrations of any component of interest, e.g., dissolved organic carbon (DOC). Obtaining accurate estimates of concentrations at aquatic sites is important for understanding fluxes of organismal abundances or nutrient levels. However, the sampling process can alter concentrations at sampling sites by extracting water from the system, because the extracted water is then replaced with water flowing into the system from the surrounding environment. When concentrations are higher at the sampling site than in the surrounding environment, extracting water from the site of interest results in dilution of concentrations at the sampling site and in the sample. The sampling process is assumed to be stochastic, since it is human operated; other aspects of this system are also expected to be stochastic. We created a model that determines how dilution affects VLP concentration in the sample and at the sampling site for the system of interest. This model is based on two ordinary differential equations that calculate the VLP flux rate from the sampling site to the sample.