Abstract
AbstractStings 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.
Highlights
The Cubozoa are a class of jellyfish with relatively low species diversity (~50 species; Bentlage et al 2010; Kingsford & Mooney, 2014)
Our specific aims were as follows: (1) develop species-specific primers to detect presence of each of these cubozoans; (2) experimentally determine the degradation rate of cubozoan Environmental DNA (eDNA); (3) determine if eDNA could detect cubozoan medusae in the field and ascertain if the amount of eDNA correlated with abundance as estimated from visual surveys; (4) determine if presence of cryptic cubozoan polyps can be detected with eDNA at times when medusa are absent using C. sivickisi as the model organism
This study is the first to report on the detection of small cubozoan jellyfish in marine systems using an eDNA approach
Summary
The Cubozoa (box jellyfishes) are a class of jellyfish with relatively low species diversity (~50 species; Bentlage et al 2010; Kingsford & Mooney, 2014). Envenomations and Irukandji syndrome can lead to death, or serious injury, with symptoms that include lower back pain, muscle cramps, vomiting/sweating, vasoconstriction, prostration, possible hypertension, feeling of impending doom, and acute heart failure or death (Tibballs et al, 2012) Though these jellyfishes pose major health risks to humans, their spatial rareness and elusiveness makes detection in marine waters difficult and as a result their ecology and distribution is presently poorly understood (Kingsford & Mooney, 2014; Tibballs et al, 2012). Our specific aims were as follows: (1) develop species-specific primers to detect presence of each of these cubozoans; (2) experimentally determine the degradation rate of cubozoan eDNA; (3) determine if eDNA could detect cubozoan medusae in the field and ascertain if the amount of eDNA correlated with abundance as estimated from visual surveys; (4) determine if presence of cryptic cubozoan polyps can be detected with eDNA at times when medusa are absent using C. sivickisi as the model organism
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