ORCC: Collaborative Research: Mechanisms underpinning the unusual, high CO2 sensitivity of sand lances, key forage fishes on the Northwest Atlantic Shelf

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Ocean warming and acidification are direct, predictable consequences of anthropogenic climate change with likely vast but still insufficiently understood consequences for marine life. So far, most tested fish species appear only mildly sensitive to ocean acidification, but sand lances are an exception. Sand lances are small, eel-like, schooling fishes of enormous importance as food for seabirds and mammals in temperate to polar ecosystems. Recent research conclusively demonstrated that many sand lance embryos have trouble developing and hatching under predicted future ocean conditions. This project uses modern experimental and molecular tools to understand exactly WHY sand lance embryos are so unusually sensitive and which genes and enzymes are responsible for this. Genes will also reveal whether some specific genotypes are less sensitive to warming and acidification, which can then be used to predict whether the species could evolve to be more tolerant over time. Another important objective is to test a closely related sand lance species to find out whether the high climate sensitivity might be of general concern in this important group of forage fishes. This research will provide critical information needed to protect the bioeconomy of fisheries. The project combines innovative ecological, evolutionary, and genomic research to help society anticipate looming marine ecosystem changes in the 21st century, while equipping the next generation of scientists with the needed tools and expertise to succeed in the challenges ahead. The project also creates opportunities for high school students from underprivileged Connecticut schools to accompany the team on sand lance sampling trips to Stellwagen Bank National Marine Sanctuary. Two recent studies on Northern sand lance (Ammodytes dubius), a key forage fish on offshore sand banks across the Northwest Atlantic shelf, have robustly demonstrated that predicted future CO2 conditions induce some of the most severe reductions in embryo survival and hatching success seen yet among tested fish species. This project has four objectives for revealing the mechanisms underpinning this unusual, high CO2-sensitivity as well as the ubiquity and genetic basis of this phenomenon. [1] For the first time, we will rear A. dubius offspring produced from wild spawners to late larval stages at factorial CO2 × temperature conditions to test whether sand lance larvae are as CO2-sensitive as embryos. [2] For the first time, we will use transcriptomic tools (RNAseq, RT-qPCR) to elucidate mechanisms causing ‘CO2-impaired hatching’, focusing specifically on hatching enzymes, to better understand a newly discovered mortality mechanism due to high CO2 in fishes. [3] Modern genomic approaches (low-coverage whole genome sequencing; allele frequency shifts, relatedness analyses) will reveal whether high CO2-sensitivity has a genetic basis in sand lance and could therefore evolve. [4] And for the first time, we will extend CO2 × temperature experiments to a congener, the American sand lance (A. americanus), which provides an important scientific contrast between nearshore vs. offshore species CO2-sensitivities and will yield critical insights whether high CO2-sensitivity is a wider concern within the sand lance family. This award was co-funded through the BIO/IOS Organismal Responses to Climate Change Program and the GEO/OCE Biological Oceanography Program.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.