Drivers of Antarctic krill reproductive output

Antarctic krill are small shrimp-like crustaceans that are an essential part of the marine food web of the Southern Ocean, the waters surrounding Antarctica. In the northern reaches of the Antarctic Peninsula, where Antarctic krill are most abundant, they are also the focus of a rapidly growing international fishery. Warming at the northern Antarctic Peninsula is causing fundamental changes in the marine ecosystem, negatively affecting krill. Understanding changes in krill population dynamics in response to climate change is critical both to the management of the fishery and the ability of scientists to predict changes in the Antarctic marine ecosystem. This project will have two broader societal impacts. First, the project will support the training and mentoring of two graduate students and three undergraduates for careers in oceanography. The students will be recruited from underrepresented groups in an effort to increase diversity, equity and inclusion in STEM. Second, results from this project will contribute to the development of improved population models, which are essential for the effective management of the Antarctic krill fishery. Through collaboration with US delegates on the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR, the international body that oversees the Antarctic krill fishery), the researchers will produce a policy report outlining the key findings from the study.

 

Effective population modeling relies on empirical and theoretical understanding of krill reproductive output and success, and the environmental factors that drive variability therein. Two key stages in the reproductive development of female Antarctic krill are critical to ensuring reproductive success: previtellogenesis (early egg development) and vitellogenesis (advanced egg development and spawning). The timing and duration of early egg development can determine the number of eggs produced and, consequently, the number of spawning events a female can undergo in a given season. The research team will make use of archived samples of preserved Antarctic krill collected in late winter/early spring, summer and early fall at the northern Antarctic Peninsula to assess the reproductive development stages of individual females. These data will be modeled against climatological and oceanographic data to test the hypotheses that (1) colder winter conditions will correspond with a greater proportion of the female krill population in previtellogenesis in late winter (indicative of early preparation for spawning); (2) favorable winter-summer conditions will correspond with a greater proportion of the female krill population in vitellogenesis in January (indicative of early spawning); and (3) favorable winter-summer conditions will correspond with a greater proportion of the female krill population still in vitellogenesis in March (indicative of longer spawning season). The study will advance current understanding of the environmental conditions that promote early spawning and a prolonged spawning season in Antarctic krill and will fill an important gap in current knowledge of the reproductive development and output of female Antarctic krill.

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This project is funded by the National Science Foundation, Award #2038145 .