Validation of eDNA as a viable method of detection for dangerous cubozoan jellyfish

Abstract

Stings from certain species of cubozoan jellyfish are dangerous to humans and their seasonal presence in tropical marine waters poses a significant risk to coastal communities. The detection of cubozoans is difficult due to high spatial and temporal variation in their occurrence and abundance. Environmental DNA (eDNA) has the potential to detect rare species and therefore offers potential to detect cubozoans, not only pelagic medusae, but presence of cryptic polyp life stages. The objective of this study was to validate the use of eDNA as a viable detection method for four cubozoan species (Chironex fleckeri, Copula sivickisi, Carybdea xaymacana, and Carukia barnesi). Species-specific primers were developed for each of these four cubozoans and an eDNA approach validated utilizing both laboratory and field trials. Laboratory DNA degradation experiments demonstrated that C. sivickisi DNA degraded quickly but could still be detected in sea water for up to 9 days post-jellyfish removal.Positive detection was found for C. fleckeri, C. xaymacana, and C. sivickisi medusae in the waters surrounding Magnetic Island, Queensland, in the Austral spring/summer (September-January). Based on visual surveys, there was a poor relationship between concentration of eDNA and abundance of jellyfish. Positive eDNA amplification was also found from water sampled near the substratum when C. sivickisi medusae were out of season and absent. This suggests the eDNA analysis was likely detecting C. sivickisi polyps located within the substratum. Consequently, eDNA is an effective tool to detect both the medusae and likely polyps of cubozoans. This approach provides the means to reduce the risk of envenomation to swimmers and enhance our knowledge of cubozoan ecology.

Fieldable Environmental DNA Sequencing to Assess Jellyfish Biodiversity in Nearshore Waters of the Florida Keys, United States

“…Sequence alignments conducted with MAFFT (E-INSI algorithm), and tree reconstructed with FASTTREE on Geneious Prime version 2019.1.1. study. As these box jellyfish medusae are rather large and conspicuous (Figure 7), it is conceivable that our sequences corresponded to eDNA from microscopic life stages (planulae or polyps) present at collection sites, in line with recent findings of eDNA signal detected for benthic cnidarians (Sawaya et al, 2019;Bolte et al, 2021). A. alata is the best documented species of the family Alatinidae, but at least one other has been reported in the Gulf of Mexico (Graham, 1998;Lewis et al, 2013;Lasley et al, 2016;Lawley et al, 2016).…”

Population Structures and Levels of Connectivity for Scyphozoan and Cubozoan Jellyfish

“…The phylogeny of cubozoan species has also been investigated [69,77]. The development of primers and probes allowed for the application of eDNA to detect cubozoans [78]. Further, genetic sequencing used to develop species-specific PCR primers for Chironex indrasaksajiae revealed two incipient species in Thailand (Figure 1).…”

“…Hartwick [94] did locate a wild population of C. fleckeri polyps and noted that young medusae occurred nearby; however, no data on the relationship between polyp and medusae abundance were collected. The polyps of most jellyfish are difficult to find, but studies on connectivity may be refined through the detection of polyp beds using eDNA, as has been done for the cubozoan Copula sivickisi [78].…”

An environmental DNA metabarcoding approach versus a visual survey for reefs of Koh Pha‐ngan in Thailand

“…It is collectable directly from the water column, benthic sediments, or fecal and gut collections (Berry et al, 2017; Koziol et al, 2019; Rodríguez‐Ezpeleta et al, 2021; Taberlet et al, 2012). In recent years, eDNA has emerged as a breakthrough approach to surmount the challenges of biodiversity monitoring and management; it has been used to successfully detect invasive, rare, cryptic, and bioindicator species (Bohmann et al, 2014; Bolte et al, 2021; Deiner et al, 2017; Mariani et al, 2021; Rees et al, 2014; Ruppert et al, 2019).…”