Robust prediction of population responses to changing environments requires the integration of factors controlling population dynamics with processes affecting distribution. This is true everywhere but especially in polar pelagic environments. Biological cycles for many polar species are synchronised to extreme seasonality, while their distributions may be influenced by both the prevailing oceanic circulation and sea-ice distribution. Antarctic krill (๐๐ถ๐ฑ๐ฉ๐ข๐ถ๐ด๐ช๐ข ๐ด๐ถ๐ฑ๐ฆ๐ณ๐ฃ๐ข) is one such species exhibiting a complex life history that is finely tuned to the extreme seasonality of the Southern Ocean. Dependencies on the timing of optimal seasonal conditions has led to concerns over the effects of future climate on krillโs population status, particularly given the speciesโ important role within Southern Ocean ecosystems.
Under a changing climate, established correlations between environment and species may breakdown. Developing the capacity for predicting krill responses to climate change therefore requires methods that can explicitly consider the interplay between life history, biological conditions, and transport. The Spatial Ecosystem And Population Dynamics Model (SEAPODYM) is one such framework that integrates population and general circulation modelling to simulate the spatial dynamics of key organisms. Here, we describe a modification to SEAPODYM, creating a novel model โ KRILLPODYM โ that generates spatially resolved estimates of krill biomass and demographics. This new model consists of three major components: (1) an age-structured population consisting of five key life stages, each with multiple age classes, which undergo age-dependent growth and mortality, (2) six key habitats that mediate the production of larvae and life stage survival, and (3) spatial dynamics driven by both the underlying circulation of ocean currents and advection of sea-ice.
Here we present the first results of KRILLPODYM, using published deterministic functions of population processes and habitat suitability rules. Initialising from a non-informative uniform density across the Southern Ocean our model independently develops a circumpolar population distribution of krill that approximates observations. The model framework lends itself to applied experiments aimed at resolving key population parameters, life-stage specific habitat requirements, and dominant transport regimes, ultimately informing sustainable fishery management.
This dataset represents KRILLPODYM modelled estimates of Antarctic krill circumpolar biomass distribution for the final year of a 12-year spin up. Biomass distributions are given for each of the five key life stages outlined above.
The accompanying background, model framework and initialisation description can be found in the following reference paper:
๐๐ฟ๐ฒ๐ฒ๐ป ๐๐, ๐ง๐ถ๐๐ฎ๐๐ฑ ๐ข, ๐๐ฒ๐๐๐น๐ฒ๐ ๐ฆ, ๐๐ผ๐ฟ๐ป๐ฒ๐ ๐ฆ๐ฃ, ๐๐ถ๐ป๐ฑ๐ฒ๐น๐น ๐ ๐, ๐ง๐ฟ๐ฒ๐ฏ๐ถ๐น๐ฐ๐ผ ๐ฅ, ๐๐ผ๐ป๐ฐ๐ต๐ผ๐ป ๐, & ๐๐ฒ๐ต๐ผ๐ฑ๐ฒ๐ ๐ฃ. (2023) KRILLPODYM: a mechanistic, spatially resolved model of Antarctic krill distribution and abundance. ๐๐ณ๐ฐ๐ฏ๐ต๐ช๐ฆ๐ณ๐ด ๐ช๐ฏ ๐๐ข๐ณ๐ช๐ฏ๐ฆ ๐๐ค๐ช๐ฆ๐ฏ๐ค๐ฆ, 10 Article 1218003. https://doi.org/10.3389/fmars.2023.1218003
