This document has been written for wetland managers, researchers, and monitoring specialists. For wetland managers, it serves as a resource for identifying and understanding biological impacts that could result from regulated and unregulated activities in wetlands. For researchers and monitoring specialists, it facilitates interpretation of collected data by providing a context of what we already know. In preparing this, our sole focus has been to update a literature review on the same topic sponsored and published previously by the USEPA. As such, this document is not intended as stand-alone guidance for persons wishing to learn how to develop wetland biomonitoring programs, or for persons seeking to prioritize research.