Environmental changes are prominent in Arctic ecosystems, where the distribution, abundance, life history, and health of marine organisms such as the bowhead whale (Balaena mysticetus) are tightly connected to sea ice and sea temperature. However, due to logistical and other challenges of data collection in the Arctic, appropriate assessments of past, present and future effects of climate change and human activities are lacking for many Arctic species. Environmental DNA (eDNA) is emerging as a noninvasive and cost‐effective way of obtaining genetic material from the environment and has the potential to complement traditional methods for biodiversity and genetic monitoring. In this study, we investigate whether eDNA isolated from seawater samples has the capacity to capture the genetic diversity of bowhead whales in Disko Bay, West Greenland, for the implementation of long‐term genetic monitoring programs of key Arctic marine species. A total of 41 eDNA “footprint” samples were obtained from the water surface after a whale had dived and an additional 54 eDNA samples were collected along transect lines. Samples were screened for bowhead DNA using a species‐specific qPCR primer and probe assay, and a subset of 30 samples were successfully Sanger‐sequenced to generate individual mitochondrial control region haplotypes. Moreover, by shotgun sequencing ten footprint samples on an Illumina NovaSeq platform we show that footprints generally contain less than 1% endogenous DNA, resulting in partial mitochondrial genomes in four samples out of ten samples. Our findings suggest that sampling in the footprint or wake of traveling animals is a promising method for capturing the genetic diversity of bowhead whales and other marine megafauna. With optimization of sampling and target DNA sequencing for higher endogenous DNA yield, seawater eDNA samples have a large potential for implementation in the long‐term population genetic monitoring of marine megafauna in the Arctic and elsewhere.
Studies of cetacean evolution using genetics and other biomolecules have come a long way—from the use of allozymes and short sequences of mitochondrial or nuclear DNA to the assembly of full nuclear genomes and characterization of proteins and lipids. Cetacean research has also advanced from using only contemporary samples to analyzing samples dating back thousands of years, and to retrieving data from indirect environmental sources, including water or sediments. Combined, these studies have profoundly deepened our understanding of the origin of cetaceans; their adaptation and speciation processes; and of the past population change, migration, and admixture events that gave rise to the diversity of cetaceans found today.
Marine mammals in the North Atlantic have experienced severe depletions due to overexploitation. While some species and populations have now recovered, there are numerous other anthropogenic activities impacting their North Atlantic ecosystem. Studying marine mammals is often associated with logistical challenges, and many species have an elusive nature, resulting in substantial knowledge gaps on the distribution, abundance and diversity of marine mammals in the North Atlantic. Environmental DNA (eDNA) is an emerging tool in biodiversity monitoring and has successfully been demonstrated to complement traditional monitoring methods for a wide range of marine taxonomic groups. The promising potential of seawater eDNA is owe to advances within an array of molecular methods used to extract, detect and/or sequence the genetic material of marine organisms from a single seawater sample. We present a literature review of eDNA studies of marine mammals and discuss the potential applications and practical challenges of eDNA in marine mammal research, management and conservation. Environmental DNA has already been introduced to a wide range of applications within marine mammal science, from detection of endangered species to population genetic assessments. Furthermore, eDNA has the power to capture other biologically important species in the marine ecosystem and food web, which could facilitate insight into the spatiotemporal variation of different marine communities in a changing environment. With methodological and technological standardization, eDNA based approaches have a promising potential to be integrated into regular monitoring practices and management strategies.
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