Modeling Environmental DNA Transport in the Coastal Ocean Using Lagrangian Particle Tracking

Elizabeth A Andruszkiewicz,Christopher A Edwards,Jeffrey R Koseff,Alexandria B Boehm,Nicholas T Ouellette,Oliver B Fringer,Anna B Lowe

doi:10.3389/fmars.2019.00477

Elizabeth A Andruszkiewicz, Christopher A Edwards + Show 5 more

Open Access

https://doi.org/10.3389/fmars.2019.00477

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Abstract

A number of studies have illustrated the utility of environmental DNA (eDNA) for detecting marine vertebrates. However, little is known about the fate and transport of eDNA in the ocean, thus limiting the ability to interpret eDNA measurements. In the present study, we explore how fate and transport processes affect oceanic eDNA in Monterey Bay, California, USA (MB). Regional ocean modeling predictions of advection and mixing are used for an approximately 10,000 km2 area in and around MB to simulate the transport of eDNA. These predictions along with realistic settling rates and first-order decay rate constants are applied as inputs into a particle tracking model to investigate the displacement and spread of eDNA from its release location. We found that eDNA can be transported on the order of tens of kilometers in a few days and that horizontal advection, decay, and settling have greater impacts on the displacement of eDNA in the ocean than mixing. The eDNA particle tracking model was applied to identify possible origin locations of eDNA measured in MB using a quantitative PCR assay for Northern anchovy (Engraulis mordax). We found that eDNA likely originated from within 40 km and south of the sampling site if it had been shed approximately 4 days prior to sampling.

Highlights

Oceans cover two-thirds of the planet and contain a vast biodiversity of organisms from microbes to whales
An initial case was examined in which there was no decay of environmental DNA (eDNA) to understand how far, in the 7-day time limit, it may be transported from its source and to investigate the effect of settling rate on displacement and spread (Figure 4)
As expected, with settling, the vertical displacement and spread of eDNA increased; displacement of the center of mass was approximately 500 m and the spread increased to approximately 100–125 m (Figure 4D)

Summary

Introduction

Oceans cover two-thirds of the planet and contain a vast biodiversity of organisms from microbes to whales. Humankind relies on marine organisms for food, medicines, and ecosystem services (de Groot et al, 2010; Hattam et al, 2015). A key reason for this is that biomonitoring data sets used to characterize abundance and distribution rely mostly on human observations, and are temporally and spatially sparse (Schratzberger et al, 2002; Edgar et al, 2004). There remains an urgent need to develop spatially and temporally high-fidelity technologies to Modeling Environmental DNA Transport in the Ocean characterize the abundance and distribution of marine organisms that are cost effective, accurate, and rapid so that we can fully understand how anthropogenic and natural changes are impacting biodiversity in the ocean

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