A transcriptomic resource for the northern krill Meganyctiphanes norvegica based on a short-term temperature exposure experiment.

The northern krill, Meganyctiphanes norvegica, is an important component of the pelagic food web across the North Atlantic. Widespread from the Mediterranean to the Subarctic Atlantic, populations appear to be strongly adapted to local temperatures, and seem to have very little plasticity. The goal of this study was to create and annotate a de novo transcriptome assembly to allow for comparative and physiological studies and to explore the gene expression response of M. norvegica from the Gulf of Maine to two different temperature conditions. Our Trinity assembly produced 405,497 transcripts with ~16% annotation success versus nr with a stringent cutoff (>1e), and substantial cross-annotation versus FlyBase and other published pelagic crustacean transcriptomes. There were 122 transcripts that were differentially expressed based on our 2-day 9 versus 12°C temperature exposure, and their annotation suggested changes in energetic metabolism and molting. These results generate a useful molecular resource for further more directed studies as well as provide initial insight into the physiological processes that may shape the temperature response of the northern krill.