KRILLPODYM: a mechanistic, spatially resolved model of Antarctic krill distribution and abundance

• Published in: Frontiers in Marine Science
• Main Authors: David B. Green, Olivier Titaud, Sophie Bestley, Stuart P. Corney, Mark A. Hindell, Rowan Trebilco, Anna Conchon, Patrick Lehodey
• Format: Article in Journal/Newspaper
• Language: English
• Published: Frontiers Media S.A. 2023
• Subjects: Southern Ocean; ecosystem modelling; earth systems; population connectivity; fisheries; mid-trophic prey; Science; Q; General. Including nature conservation; geographical distribution; QH1-199.5; Antarctic; Antarc*; Antarctic Krill; Euphausia superba; Sea ice
• Online Access: https://doi.org/10.3389/fmars.2023.1218003; https://doaj.org/article/a5e6833e55874c6ca6d205060c50ce88

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 (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 have 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. We present the first results of KRILLPODYM, using published deterministic functions of population processes and habitat suitability rules. Initialising from ...