Applying coralline algal sclerochronology to Arctic fishery implications: Geochemical evidence of primary productivity variability over 200 years

The Arctic is one of the regions most affected by climate change, globally. Recent hydro-ecological studies have pointed to increasing primary productivity due to greater riverine or terrestrial nutrient runoff and solar irradiance as a result of warming temperatures and sea ice loss. This has significant implications for Arctic marine food webs and fisheries management, as any shift in primary producers can cause ecological cascades within the Arctic ecosystem. However, there is a lack of highly resolved long-term instrumental data from many Arctic regions, limiting our ability to disentangle hydro-ecological dynamics and track its inter-annual variability prior to the satellite record (1979-present). Here, we present annually-resolved geochemical data – barium/calcium and stable carbon isotope ratios (Ba/Ca and δ¹³C) – from the calcifying coralline red algae, Clathromorphum compactum, collected in Lancaster Sound, Nunavut, Canada, suggesting larger and longer-lasting phytoplankton blooms over the last 30 years. Through this proxy data, we also demonstrate the variability of primary productivity over the last 200 years and its links to atmospheric, cryospheric and oceanographic trends. We compare these data to those derived from C. compactum specimens collected in other regions including glacially impacted sites in the Canadian Arctic Archipelago and Svalbard, as well as subarctic sites in the Labrador Sea. The contrasting results from these different Arctic regions reveal geographic variability in in barium and carbon dynamics in coastal ocean waters due to nearness to freshwater and glacier runoff. We conclude by discussing the implications of these findings for fisheries management and Indigenous livelihoods.

Primary Presenter: Natasha Leclerc, Memorial University of Newfoundland (natasha.leclerc@mail.utoronto.ca)

Authors:

Natasha Leclerc, Memorial University of Newfoundland  (ndhlnl2@mun.ca)

Julia Kim, University of Toronto St George  (juliaym.kim@mail.utoronto.ca)

Gauri Menon, University of Toronto Mississauga  (gaurisans.menon@mail.utoronto.ca)

Joshita Sehgal, University of Manitoba  (joshita.sehgal@mail.utoronto.ca)

Mohammad Siddiqui, University of Toronto Mississauga  (afzal.siddiqui@mail.utoronto.ca)

Maya Smith, University of Toronto Mississauga  (maya.smith@mail.utoronto.ca)

Meghan Zulian, University of California Davis  (mzulian@ucdavis.edu)

Minoli Dias, University of Toronto Mississauga  (minoli.dias@mail.utoronto.ca)

Steffen Hetzinger, Christian-Albrechts-Universität zu Kiel  (steffen.hetzinger@ifg.uni-kiel.de)

Alexandra Tsay, University of Geneva  (alexandra.tsay@unige.ch)

Jochen Halfar, University of Toronto  (jochen.halfar@utoronto.ca)