Magnetic Signature of Vertically Migrating Aggregations in the Ocean

Abstract

Biologically generated mixing from vertically migrating aggregations of plankton remains a poorly understood mechanism by which heat and solutes are potentially mixed in the ocean (Dabiri, 2009;Dewar et al., 2006;Houghton et al., 2018;Wilhelmus & Dabiri, 2014). While the induced flow and stirring associated with an isolated animal occur at the scale of the swimmer (Visser, 2007), plankton often exist in dense swarms over 10s of meters in height and 100s of meters in width (Huntley & Zhou, 2004;Sato et al., 2013), and collectively traverse 100s of meters during their diel vertical migrations (Sato et al., 2013;Wiebe et al., 1979). The emergence of aggregation-scale mixing eddies comparable to the stratification length scales of the water column has been proposed as a potential mechanism through which vertically migrating aggregations can induce appreciable transport in the water column through which the organisms migrate (

Limnology and Oceanography Bulletin Volume 33 Number 2 May 2024 1‐95

“…To address this challenge of identifying DVM in the field, new concepts are emerging to indirectly detect biogenic ocean mixing based on associated physics or biology. These include strategies that would leverage the magnetic signature of vertical flow currents in Earth's geomagnetic field (Fu and Dabiri 2023), or exploit sampling of environmental DNA associated with DVM (Office of Naval Research 2022). Both of these approaches could circumvent challenges associated with uncertainties in identifying swimming aggregations in field studies, while also avoiding triggering escape or avoidance behaviors that can cause organisms to avoid measurement instrumentation deployed in their vicinity.…”

Do Swimming Animals Mix the Ocean?

“…To address this challenge of identifying DVM in the field, new concepts are emerging to indirectly detect biogenic ocean mixing based on associated physics or biology. These include strategies that would leverage the magnetic signature of vertical flow currents in Earth's geomagnetic field (Fu and Dabiri 2023), or exploit sampling of environmental DNA associated with DVM (Office of Naval Research 2022). Both of these approaches could circumvent challenges associated with uncertainties in identifying swimming aggregations in field studies, while also avoiding triggering escape or avoidance behaviors that can cause organisms to avoid measurement instrumentation deployed in their vicinity.…”