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

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

Towards a Precise Measurement of Matter Clustering: Lyman-alpha Forest Data at Redshifts 2-4

We measure the filling factor, correlation function, and power spectrum of transmitted flux in a large sample of Lya forest spectra, comprised of 30 Keck HIRES spectra and 23 Keck LRIS spectra. We infer the linear matter power spectrum P(k) from the flux power spectrum P_F(k), using an improved version of the method of Croft et al. (1998) that accounts for the influence of z-space distortions, non- linearity, and thermal broadening on P_F(k). The evolution of the shape and amplitude of P(k) over the range z= 2-4 is consistent with gravitational instability, implying that non-gravitational fluctuations do not make a large contribution. Our fiducial measurement of P(k) comes from data with = 2.72. It has amplitude Delta^2(k_p)=0.74^0.20_-0.16 at wavenumber k_p=0.03 (km/s)^-1 and is well described by a power-law of index -2.43 +/- 0.06 or by a CDM-like power spectrum with shape parameter Gamma'=1.3^+0.7_-0.5*10^-3 (km/s) at z=2.72. For Omega_m=0.4, Omega_Lam=0.6, the best-fit Gamma =0.16 (h^-1mpc)^-1, in good agreement with the 2dF Galaxy Redshift Survey, and the best-fit sigma_8=0.82 (Gamma/0.15)^-0.44. Matching the observed cluster mass function and our Delta^2(k_p) in spatially flat models requires Omega_m=0.38^+0.10_-0.08 + 2.2 (Gamma-0.15). Matching Delta^2(k_p) in COBE-normalized, flat CDM models with no tensor fluctuations requires Omega_m = (0.29 +/-0.04) n^-2.89 h_65^-1.9. The Lya forest complements other probes of P(k) by constraining a regime of redshift and lengthscale not accessible by other means, and the consistency of these inferred parameters with independent estimates provides further support for inflation, cold dark matter, and vacuum energy (abridged).Comment: Revised version fixes error in normalization (now 1 sigma higher). ApJ in press Dec 10 issue, 34 pages, 23 postscript figures, emulateapj.st

Facial Identity Recognition in the Broader Autism Phenotype

Peer reviewedPublisher PD