Collaborative Research: BoCP-Implementation: Quantifying the Response of Biodiverse Freshwater Ecosystems to Abrupt and Progressive Environmental Change

Collaborative Research: BoCP-Implementation: Quantifying the response of biodiverse freshwater ecosystems to abrupt and progressive environmental change ABSTRACT & MAJOR GOALS Coastal freshwater ecosystems are well-known for being biologically diverse and they provide important services to humans worldwide. With continued global warming, these coastal systems are at risk of undergoing dramatic environmental changes associated with rising seas. Future sea-level rise scenarios suggest either a gradual or a rapid upland migration of marine waters, yet the response of freshwater systems to these novel environmental conditions is unknown. Establishing an understanding of how ecosystems respond to marine water inundation is difficult to constrain using only modern observations. The low-lying freshwater ecosystem in eastern Guatemala, which is made up of two interconnected lakes and several important wetlands (known as the Izabal/Golfete system), has undergone two significant environmental changes during the recent past, one associated with a rapid and a second with a gradual inundation by marine waters. These two historical natural experiments provide an unparalleled opportunity to investigate how the Izabal/Golfete system responded to different degrees of environmental stress. This project will constrain these changes using sedimentological, geochemical, biological, and genetic methods. We aim to reveal how the environment and biota responded to these two scenarios of marine water inundation, providing crucial information to assess how this and other at-risk ecosystems will respond to future sea-level rise. We aim to provide essential data for managers and entities to safeguard these important biological hotspots, establish strong international relationships, and engage with local communities and governmental and educational institutions in the US and Guatemala. Future sea-level rise models suggest that marine flooding of coastal freshwater ecosystems will increase in frequency, yet the response of these biologically-diverse systems to different degrees of marine inundation is unknown. This project will use the Izabal/Golfete system, a freshwater ecosystem in eastern Guatemala, to assess how variations in marine inundation affected the environment and its functional diversity. Our study is therefore in an unrivaled position to make contributions to our understanding of how ecosystems function and respond to marine flooding events. We will do this by collecting sediment cores, surface sediment, fish, and water samples and generate high- resolution time series of environmental and biological changes using sedimentological, inorganic and organic geochemical, micropaleontological, and genetic data. The combination of datasets will allow us to model functional diversity through temporally different environmental stressors and transitions, allowing us to understand and forecast the response of freshwater ecosystems to marine inundation events. Finally, the highly integrative, multi-institution, and international nature of this project will be of significant benefit to the participating students, will allow us to establish several outreach programs in US and Guatemalan schools and museums, and will provide a foundation for understanding the impacts of potential change to the regional system in eastern Guatemala and other similar systems worldwide.