Using sea-ice to calibrate a dynamic trophic model for the Western Antarctic Peninsula

Abstract

The pelagic ecosystems of the Western Antarctic Peninsula are dynamic and changing rapidly in the face of sustained warming. There is already evidence that warming may be impacting the food web. Antarctic krill, Euphausia superba , is an ice-associated species that is both an important prey item and the target of the only commercial fishery operating in the region. The goal of this study is to develop a dynamic trophic model for the region that includes the impact of the sea-ice regime on krill and krill predators. Such a model may be helpful to fisheries managers as they develop new management strategies in the face of continued sea-ice loss. A mass balanced food-web model (Ecopath) and time dynamic simulations (Ecosim) were created. The Ecopath model includes eight currently monitored species as single species to facilitate its future development into a model that could be used for marine protected area planning in the region. The Ecosim model is calibrated for the years 1996–2012. The successful calibration represents an improvement over existing Ecopath models for the region. Simulations indicate that the role of sea ice is both central and complex. The simulations are only able to recreate observed biomass trends for the monitored species when metrics describing the sea-ice regime are used to force key predator-prey interactions, and to drive the biomasses of Antarctic krill and the fish species Gobionotothen gibberifrons . This model is ready to be used for exploring results from sea-ice scenarios or to be developed into a spatial model that informs discussions regarding the design of marine protected areas in the region.

Changing circumpolar distributions and isoscapes of Antarctic krill: Indo‐Pacific habitat refuges counter long‐term degradation of the Atlantic sector

“…Large scale analyses are hampered, however, by a relatively poor understanding of how krill‐based food webs vary between sectors and different areas of ecological significance. Detailed food web reconstructions have only been completed for a handful of systems in the Southern Ocean, and these show major differences in reliance on E. superba (e.g., Hill et al 2012; Pinkerton and Bradford‐Grieve 2014; Dahood et al 2019). Furthermore, some predator species may migrate or integrate across systems (Bengtson Nash et al 2018; Hindell et al 2020), requiring a circumpolar‐scale baseline of their potential food sources.…”

The Celtic Sea Through Time and Space: Ecosystem Modeling to Unravel Fishing and Climate Change Impacts on Food-Web Structure and Dynamics

“…PP and zooplankton suitable habitat (ZSH) time-series drove the production of phytoplankton groups (see Christensen et al, 2009) and the consumption of zooplankton (small and large mesozooplankton, macrozooplankton), respectively. More specifically, ZSH time-series were used as multiplier of the arena area for zooplankton-phytoplankton interactions, of zooplankton vulnerability for fish-zooplankton interactions, and of both parameters for zooplankton-zooplankton interactions (see Supplementary Appendix SF; Dahood et al, 2019). Temperature variations and corresponding preference functions to the model drove the consumption of fish groups (foraging environmental response; see Bentley et al, 2017;Serpetti et al, 2017;Corrales et al, 2018).…”

Time-Dynamic Food Web Modeling to Explore Environmental Drivers of Ecosystem Change on the Kerguelen Plateau

“…Therefore, this model can be seen as a representation of the mean state of the ecosystem from the late 1980s to 2018. A similar approach has been used for Ecosim models in other regions of the Southern Ocean (e.g., Dahood et al, 2019).…”