A large scale temporal and spatial environmental DNA biodiversity survey of offshore marine vertebrates in Brazil following the upriver Fundão tailings dam failure
Lines, Rose et al. (2022), A large scale temporal and spatial environmental DNA biodiversity survey of offshore marine vertebrates in Brazil following the upriver Fundão tailings dam failure, Dryad, Dataset, https://doi.org/10.5061/dryad.sqv9s4n3t
Seawater contains a wealth of genetic information, representing the biodiversity of numerous species residing within a particular marine habitat. Environmental DNA (eDNA) metabarcoding offers a cost effective, non-destructive method for large scale monitoring of environments, as diverse taxonomic groups are detected using metabarcoding assays. A large-scale eDNA monitoring program of marine vertebrates was conducted across three sampling seasons (Spring 2018, Autumn 2019 and Spring 2019) in coastal waters of Brazil. The program was designed to monitor for signs of impact and/or recovery in the region following the Fundão tailings dam failure in November 2015. A total of 445 water samples were collected around the mouths of eight river systems, covering approximately 500km of coastline. Metabarcoding assays targeting the mitochondrial genes 16S rRNA and COI were used to detect fish, marine mammals and elasmobranchs. We detected temporal differences between seasons and spatial differences between rivers/estuaries sampled. Changes in marine biodiversity over time could not be attributed to effects of, or recovery after, the dam failure event as similar species assemblage patterns were observed at the impacted study area and an unimpacted reference study area. In addition, the lack of eDNA samples from before the dam failure to use as a comparison with current data, prevented more detailed molecular interpretation of the dam failure on the marine vertebrate diversity in the area affected. Overall, the largest eDNA survey in Brazil to date, revealed 207 taxa from Class Actinopterygii (fish), 18 taxa from Class Chondrichthyes (sharks and rays), 4 taxa of marine and estuarine mammals and 23 species of conservation significance including 2 species of endangered dolphin. Our large-scale study reinforces the value eDNA metabarcoding can bring when monitoring the biodiversity of coastal environments and demonstrates the importance of collection of time-stamped environmental samples to better understand the impacts of anthropogenic activities.
Seawater samples collected along the coastline of Brazil were sequenced using 16S and COI assays. Bioinformatic analysis was performed in accordance with Mousavi-Derazmahalleh et al., (2021). eDNAFlow, an automated, reproducible and scalable workflow for analysis of environmental DNA (eDNA) sequences exploiting Nextflow and Singularity. Molecular Ecology Resources. doi: 10.1111/1755-0998.13356.
This work was commissioned and funded by BHP Brazil as part of a larger routine marine environmental monitoring program in coastal waters of Espírito Santo and Bahia.
Fasta files for each sample and metabarcoding assey have been provided.