Magnetic signature of vertically migrating aggregations in the ocean

TL;DR

This paper proposes a novel magnetometry-based method to detect and quantify the magnetic signatures of migrating plankton aggregations, offering a non-invasive way to study their role in ocean mixing and climate impact.

Contribution

The study introduces a new approach using modern magnetometry, including quantum-enhanced techniques, to remotely detect flow-induced magnetic fields from migrating organisms.

Findings

Magnetic signatures are proportional to fluid transport by migrations.

These signals can be detected remotely at significant distances.

The method offers a new way to quantify ocean mixing contributions.

Abstract

The transport of heat and solutes by vertically migrating aggregations of plankton has long been explored as a potentially important source of ocean mixing. However, direct evidence of enhanced mixing due to these migrations remains challenging to obtain and inconclusive. These shortcomings are due to the limitations of current measurement techniques, i.e., velocimetry techniques, which require a priori knowledge of the precise aggregation location and typically trigger animal avoidance behavior from introducing instrumentation into the migration. Here we develop a new approach to overcome these longstanding limitations by leveraging advancements in modern magnetometry to detect the flow-induced magnetic fields that naturally arise from seawater as it moves through the Earth's geomagnetic field. We derive quantitative predictions showing that these flow-induced magnetic fields in the vicinity of migrating aggregations have a strength proportional to the integrated fluid transport due to the migration. Importantly these magnetic signatures are potentially detectable remotely at a significant distance far from the aggregation and region of moving fluid with emerging quantum-enhanced magnetometry techniques such as Nitrogen-Vacancy centers in diamond. These results provide a new, testable framework for quantifying the significance of fluid transport in the ocean due to swimming organisms that may finally resolve a scientific debate with potentially enormous implications for our understanding of ocean dynamics and climate change.