Biolocomotion and premelting in ice

TL;DR

This paper explores how biota in ice environments use bio-enhanced premelting and active biolocomotion, influenced by thermal and chemical gradients, to navigate and survive in icy habitats, with implications for astrobiology and climate science.

Contribution

It introduces the concept of bio-enhanced premelting and models bioparticle motion in ice using active Ornstein-Uhlenbeck dynamics, revealing how nutrients and temperature gradients affect biolocomotion.

Findings

Thermal regelation is modified by biolocomotion in icy environments.

Nutrient sources influence the direction and efficiency of bioparticle movement.

Bio-enhanced premelting impacts the survival strategies of extremophiles in ice.

Abstract

Biota are found in glaciers, ice sheets and permafrost. Ice bound micro-organisms evolve in a complex mobile environment facilitated or hindered by a range of bulk and surface interactions. When a particle is embedded in a host solid near its bulk melting temperature, a melted film forms at the surface of the particle in a process known as interfacial premelting. Under a temperature gradient, the particle is driven by a thermomolecular pressure gradient toward regions of higher temperatures in a process called thermal regelation. When the host solid is ice and the particles are biota, thriving in their environment requires the development of strategies, such as producing exopolymeric substances (EPS) and antifreeze glycoproteins (AFP) that enhance the interfacial water. Therefore, thermal regelation is enhanced and modified by a process we term {\em bio-enhanced premelting}. Additionally, the motion of bioparticles is influenced by chemical gradients influenced by nutrients within the icy host body. We show how the overall trajectory of bioparticles is controlled by a competition between thermal regelation and directed biolocomotion. By re-casting this class of regelation phenomena in the stochastic framework of active Ornstein-Uhlenbeck dynamics, and using multiple scales analysis, we find that for an attractive (repulsive) nutrient source, that thermal regelation is enhanced (suppressed) by biolocomotion. This phenomena is important in astrobiology, the biosignatures of extremophiles and in terrestrial paleoclimatology.