Ballast Water Exchange and Invasion Risk Posed by Intracoastal Vessel Traffic: An Evaluation Using High Throughput Sequencing

Abstract

Ballast water remains a potent vector of non-native aquatic species introductions, despite increased global efforts to reduce risk of ballast water mediated invasions. This is particularly true of intracoastal vessel traffic, whose characteristics may limit the feasibility and efficacy of management through ballast water exchange (BWE). Here we utilize high throughput sequencing (HTS) to assess biological communities associated with ballast water being delivered to Valdez, Alaska from multiple source ports along the Pacific Coast of the United States. Our analyses indicate that BWE has a significant but modest effect on ballast water assemblages. Although overall richness was not reduced with exchange, we detected losses of some common benthic coastal taxa (e.g., decapods, mollusks, bryozoans, cnidaria) and gains of open ocean taxa (e.g., certain copepods, diatoms, and dinoflagellates), including some potentially toxic species. HTS-based metabarcoding identified significantly differentiated biodiversity signatures from individual source ports; this signal persisted, though weakened, in vessels undergoing BWE, indicating incomplete faunal turnover associated with management. Our analysis also enabled identification of taxa that may be of particular concern if established in Alaskan waters. While these results reveal a clear effect of BWE on diversity in intracoastal transit, they also indicate continued introduction risk of non-native and harmful taxa.

Metabarcoding as a tool to enhance marine surveillance of nonindigenous species in tropical harbors: A case study in Tahiti

“…These differences in taxonomic classifications may be due, in part, to differences in the amplification efficiency of primers for different taxa (Leray & Knowlton, 2015). These known artifacts may impact results, which can have important implications in the marine biosecurity context (von Ammon et al., 2018a; Darling et al., 2018, 2020; Wood, et al., 2019a).…”

Status and prospects of marine NIS detection and monitoring through (e)DNA metabarcoding

“…Borrell et al 2017, Rey et al 2019, Suarez-Menendez et al 2020 or to zooplankton (e.g. Zaiko et al 2015a,b, Abad et al 2016, Darling et al 2018, Lin et al 2020. Environmental DNA can be extracted directly from environmental samples, such as water and sediments, and can originate from organisms' body parts, mucus, tissues, cells, secreted faeces or extracellular DNA, leaking to the environment through the normal life or upon death of organisms (Turner et al 2014, Sassoubre et al 2016, Holman et al 2019.…”

“…1B). Zooplankton sampling has been conducted in ships ballast water (Zaiko et al 2015a,b, Ghabooli et al 2016, Darling et al 2018, Lin et al 2020, boats bilge water (Fletcher et al 2017), and in sea water in ports and marinas or nearby natural habitats , Zaiko et al 2015c, Abad et al 2016, Stefanni et al 2018, Couton et al 2019, Leduc et al 2019, Rey et al 2020, Westfall et al 2020. The monitoring of larvae in plankton samples in ports or in the close vicinities, may provide key information about NIS introduction status or detect their presence at an earlier stage (Couton et al 2019).…”

“…4). (Darling et al 2018). The 18S region is also the formal primary marker adopted for barcoding protists (Pawlowski et al 2012).…”

“…When targeting a broad taxonomic range, the inadequate choice of primers can lead to the underrepresentation or even failed detections of NIS, resulting in false negatives of potential taxa of concern (Darling et al 2018, von Ammon et al 2018b. For instance, DNA metabarcoding employing 18S and COI, failed to detect several bryozoan taxa in a New Zealand's marina, despite several entries can been found for those species and markers on GenBank (von Ammon et al 2018b).…”