CREST-PRF: Linking physiology and demography in the Eastern Mosquitofish Gambusia holbrooki

Mercado-Molina Alex E, San Juan PR

Investigators

Abstract

The Centers of Research Excellence in Science and Technology-Postdoctoral Research Fellowship (CREST-PRF) track within the CREST program supports beginning CREST Center investigators with significant potential and provides them with training and research experiences that will broaden perspectives, facilitate interdisciplinary interactions and establish them in positions of leadership within the scientific community. This CREST-PRF project is aligned with the research focus of the CREST Center for Aquatic Chemistry and the Environment (CAChE) at Florida International University. The project will focus on how mercury (Hg) affects organisms' physiology, vital rates, and local population growth. The Everglades, a network of interconnected freshwater ecosystems that includes local areas contaminated by (Hg) and its methylated or organic form, methylmercury, will provide a natural laboratory for this study. The eastern mosquitofish, Gambusia holbrooki, will be used as a model species to document the demographic and population consequences of physiological stress induced by water contaminants (Hg). Since the eastern mosquitofish play a critical role in the Everglades food webs, this project will advance our knowledge and understanding of how human-induced contaminants affect aquatic biota. Findings from this study will be useful for designing conservation and restoration activities. The research will contribute to the postdoctoral training of a Latin American student, thus increasing the number of underrepresented minority candidates pursuing a career in STEM, an important goal of the CREST-CAChE. In addition, this research project will be integrated into the education and outreach program at the Center. The overarching goal of the research is to determine whether the organism's physiological response to environmental stress regulates individual and population performance. Although other studies have examined the demographic consequences of stress in aquatic organisms, studies considering multiple life-history traits (e.g. growth, survival, and reproduction) are scarce. Furthermore, research examining how local population dynamics are affected by variation in patterns of resource allocation due to physiological stress, are warranted. This study will also test the life-history trade-off hypothesis as the basis to understand species' adaptation to environmental conditions by measuring the relationship between organisms' physiological conditions and demographic and population performance. This project will address such gaps by measuring, both in the field and in controlled lab experiments, the demographic response of G. holbrooki to mercury-induced physiological stress. The demographic data (growth, survival, and reproductive output) will be used to develop stage-based population matrix models to estimate population growth rates under different physiological pressures. By combining empirical physiological data with demographic modeling, the proposed study will be among the first to test such a relationship directly. The outcomes of this study will provide quantitative evidence of the success (or failure) of using physiological measurements as a biomarker to determine the effects of water contaminants in the demography and life-history traits of aquatic organisms.