Are Arctic productivity hotspots sources or sinks? A trait-based approach to mesozooplankton life history and energetics along advective corridors

• Main Authors: Banas, Neil, Ashjian, Carin J., Campbell, Robert G., Laidre, Kristin Liisa, Møller, Eva Friis, Nielsen, Torkel Gissel, Simon, Malene
• Format: Conference Object
• Language: English
• Published: 2018
• Subjects: Arctic; Bering Sea; Chukchi Sea; Greenland; Pacific; Chukchi; Disko Bay; Pacific Arctic; Phytoplankton
• Online Access: https://pure.au.dk/portal/da/publications/are-arctic-productivity-hotspots-sources-or-sinks-a-traitbased-approach-to-mesozooplankton-life-history-and-energetics-along-advective-corridors(5446d663-ac7d-4b50-bc08-b4d229603655).html; https://osm.agu.org/2018/

Marine productivity hotspots are usually conceived of, or defined as, sources of energy and nutrients to surrounding waters (for example, in the context of marine protected areas that serve as buffers against fisheries catch elsewhere). This study considers whether Arctic hotspots for top predators are indeed sites of net production - and thus standing in contrast to the Arctic system as a whole - or whether they are net sinks at lower trophic levels, sites that collect plankton productivity from other oceans and deliver it in concentrated form to top predators. A new model, Coltrane (Copepod Life history Traits and Adaptation to New Environments) provides a relatively simple mathematical framework for layering multiple levels of mesozooplankton biology on top of oceanographic models. It resolves 1) individual life history (strategy traits controlling growth, development, and size, diagnosed from a broad review of lab studies); 2) population dynamics (the time-dependent energy balance between growth, egg production, and predation mortality); and 3) community assembly (the envelope of viable trait combinations under particular annual cycles of prey and temperature). Advective pathways in the Atlantic and Pacific Arctic were mapped using the BIOMAS oceanographic model, and Coltrane was used to map the energy budget of Calanus populations along northward transport corridors. Results in the Pacific Arctic show a spatial offset between the regions where biomass is transferred from phytoplankton to mesozooplankton and where it is transferred from mesozooplankton to higher predators. These results suggest that the yield of Calanus to predators in the Chukchi Sea is dependent primarily on Bering Sea phytoplankton blooms, although this complex interdependence could change as ice retreats and phytoplankton phenology shifts. Similar model results in Disko Bay, West Greenland are reinforced by a statistical analysis revealing intense predation by bowhead whales on overwintering Calanus : an unexpected trophic link from ...