DNA barcoding of the marine macroalgae from Nome, Alaska (Northern Bering Sea) reveals many trans-Arctic species

Marine macroalgal species are expected to shift northward with temperature regimes in the wake of climate change. Monitoring ecosystem shifts in the Arctic will depend on accurate and consistent species level datasets from key locations. The Northern Bering Sea is an area with limited sampling, and will be critical to monitoring the potential movement of Pacific species into the Arctic. We therefore sampled the marine flora of Nome, Alaska, and surrounding area, August 12-22 (2017). Specimens were pressed and/or preserved in silica for DNA barcoding procedures. Several genetic markers were sequenced including the 5 end of the cytochrome c oxidase subunit I gene (COI-5P; n=551), elongation factor Tu (tufA; n=41), full length reads of the internal transcribed spacer of the ribosomal cistron (ITS; n=56), and full or partial reads of the ribulose-1, 5-biphosphate carboxylase large subunit (rbcL or rbcL-3P, respectively; n=24). These collections represented eight species of green algae, 21 species of brown algae, and 24 species of red algae. Most of the species sampled (66%, n=35) represented trans-Arctic species, 17% (n=9) represented species with distributions restricted to the Pacific, 8% (n=4) represented species restricted to the Arctic, and the remaining 9% (n=5) represented previously unsampled genetic groups. Our survey revealed that the marine flora of Nome, Alaska, is largely contiguous with the North-west Atlantic. Repeated sampling from Nome and other key locations in the Northern Bering Sea (e.g., St. Lawrence Island) will be critical to further establishing baseline data for monitoring ecosystem shifts in an era of climate change.