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Using early life stage assessments to connect mechanisms of PFAS toxicity to adverse outcomes in killifish (Fundulus heteroclitus)
Citation:
Burke, T., H. Schrader, M. Francoeur, L. Mills, N. McNabb, AND B. Clark. Using early life stage assessments to connect mechanisms of PFAS toxicity to adverse outcomes in killifish (Fundulus heteroclitus). SETAC North Atlantic Chapter, 28th Annual Meeting 2022, Groton, CT, June 27 - 28, 2022.
Impact/Purpose:
This presentation evaluates developmental biological endpoints in Atlantic killifish (Fundulus heteroclitus) that contribute to our understanding of the survivability of individuals and the persistence of their populations when exposed to PFAS in the marine environment. To assess the risks associated with PFAS exposures, a variety of biological endpoints were measured, and a subset of embryos were sacrificed for ‘omics analyses. By connecting molecular mechanisms to developmental endpoints, adverse outcomes measured in killifish for specific PFAS exposures can be extrapolated to untested species and other chemical pollutants. The information presented in this research provides more insight to managers and scientists about how human activities can affect natural dynamics, ecological stressors, and ecosystem conditions.
Description:
Per- and Polyfluoroalkyl substances (PFAS) are long lasting chemicals found in the environment that have been linked to adverse impacts in fish and other species, including humans. PFAS contamination may adversely impact fish on the organismal level through a variety of pathways that may affect their development, survival, and ability to reproduce. The early life stages of fish are useful to assess the effects of pollutants because they are often more sensitive than adult stages and have the potential for later life impacts that can affect population persistence. To assess the risks associated with PFAS exposures, early developmental stages of Atlantic killifish (Fundulus heteroclitus), an ecologically important species with a well-annotated genome, were exposed to a variety of PFAS directly by aquatic exposures in standardized embryo larval assays (ELAs). In ELAs, non-destructive measurements of growth and development were monitored in individuals after exposure until 16 days post-hatching (dph). A subset of embryos was sacrificed for ‘omics analyses to discern molecular mechanisms affected by pollutant exposures. In the presented ELAs, a variety of biological endpoints were measured including embryonic survival, development, phenotypic abnormalities, and heart rate, as well as larval survival, growth, swim bladder size, and behavior. Detailed microscopic phenotyping was conducted 10 days-post-fertilization (10 dpf) and used to examine embryos for developmental abnormalities including, but not limited to abnormal head or body size, hemorrhages of the tail, head, and pericardial area, and heart features such as offset heart chambers and an elongated sinus venosus. To assess heart function, video analysis of 10 dph killifish embryos was performed with DanioScope software to determine average heart rate in beats per minute by individual embryo. Swim bladder measurements were taken to discern possible treatment effects on inflation. To measure larval length and growth, images were taken using a mounted Nikon camera and analyzed with ImageJ processing software at 0 dph, 7 dph, and 16 dph to determine larval growth rates. Larval behavior was analyzed using Ethovision software to detect differences in locomotor activity between light and dark phases. Results from these assays provide examples showing that the concentration and specific type of PFAS chemical exposure had varying effects on the frequency and severity of each developmental endpoint. These data can be used directly to inform ecological models, including Individual Based Models, under development for killifish that predict adverse chemical outcomes at the population level, which often cannot be measured directly. Furthermore, by connecting molecular mechanisms to developmental endpoints, adverse outcomes measured in killifish for PFAS exposures may be extrapolated to untested species and other related chemical pollutants.
