KRILLPODYM modelled estimates of Antarctic krill circumpolar distribution

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 (𝘌𝘶𝘱𝘩𝘢𝘶𝘴𝘪𝘢 𝘴𝘶𝘱𝘦𝘳𝘣𝘢) 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 krill’s population status, particularly given the species’ 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 – KRILLPODYM – 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:

𝗚𝗿𝗲𝗲𝗻 𝗗𝗕, 𝗧𝗶𝘁𝗮𝘂𝗱 𝗢, 𝗕𝗲𝘀𝘁𝗹𝗲𝘆 𝗦, 𝗖𝗼𝗿𝗻𝗲𝘆 𝗦𝗣, 𝗛𝗶𝗻𝗱𝗲𝗹𝗹 𝗠𝗔, 𝗧𝗿𝗲𝗯𝗶𝗹𝗰𝗼 𝗥, 𝗖𝗼𝗻𝗰𝗵𝗼𝗻 𝗔, &amp; 𝗟𝗲𝗵𝗼𝗱𝗲𝘆 𝗣. (2023) KRILLPODYM: a mechanistic, spatially resolved model of Antarctic krill distribution and abundance. 𝘍𝘳𝘰𝘯𝘵𝘪𝘦𝘳𝘴 𝘪𝘯 𝘔𝘢𝘳𝘪𝘯𝘦 𝘚𝘤𝘪𝘦𝘯𝘤𝘦, 10 Article 1218003. https://doi.org/10.3389/fmars.2023.1218003

Tags: Antarctic krill, Earth systems, Ecosystem modelling, Euphausia superba, Fisheries, Mid-trophic pelagic prey, Population connectivity, Southern Ocean, Spatial processes
Organization: Australian Ocean Data Network