Coral larvae move toward reef sounds

Free-swimming larvae of tropical corals go through a critical life-phase when they return from the open ocean to select a suitable settlement substrate. During the planktonic phase of their life cycle, the behaviours of small coral larvae (<1 mm) that influence settlement success are difficult to observe in situ and are therefore largely unknown. Here, we show that coral larvae respond to acoustic cues that may facilitate detection of habitat from large distances and from upcurrent of preferred settlement locations. Using in situ choice chambers, we found that settling coral larvae were attracted to reef sounds, produced mainly by fish and crustaceans, which we broadcast underwater using loudspeakers. Our discovery that coral larvae can detect and respond to sound is the first description of an auditory response in the invertebrate phylum Cnidaria, which includes jellyfish, anemones, and hydroids as well as corals. If, like settlement-stage reef fish and crustaceans, coral larvae use reef noise as a cue for orientation, the alleviation of noise pollution in the marine environment may gain further urgency.Mark J. A. Vermeij, Kristen L. Marhaver, Chantal M. Huijbers, Ivan Nagelkerken and Stephen D. Simpso

Single Particle Cathodoluminescence Spectroscopy with Sub-20 nm, Electron-Stable Phosphors

Lanthanide-doped nanophosphors have emerged as promising optical labels for high-resolution, "multicolor"electron microscopy. Here, we develop a library of 11 unique lanthanide-doped nanophosphors with average edge lengths of 15.2 ± 2.0 nm (N = 4284). These nanophosphors consist of an electron-stable BaYF5 host lattice doped at 25% atomic concentration with the lanthanides Pr3+, Nd3+, Sm3+, Eu3+, Tb3+, Dy3+, Ce3+, Ho3+, Er3+, Tm3+, and Yb3+. Under â 100 pA/nm2 beam current in a transmission electron microscope, each nanophosphor species exhibits strong cathodoluminescence spectra with sharp characteristic emission lines for each lanthanide. The bright emission and stability of these nanoparticles enable not only ensemble, but also single-particle cathodoluminescence spectroscopy, which we demonstrate with BaYF5:Ln3+, where Ln3+ = Tb3+, Ho3+, Er3+, Sm3+, Eu3+, or Pr3+. Single-particle cathodoluminescence corresponds directly with HAADF intensity across nanoparticles, confirming high spatial localization of the measured cathodoluminescence signal of lanthanide-doped nanophosphors. Our synthesis and characterization of sub-20 nm, electron-stable nanophosphors provides a robust material platform to achieve single-molecule labeled correlative cathodoluminescence electron microscopy, a critical foundation for high-resolution correlation of single molecules within the context of cellular ultrastructure

Exploring Scientific Ideas in Informal Settings: Activities for Individuals with Visual Impairments

Four new modules for the scientific education of individuals with visual disabilities are reported. Designed for informal settings, the modules are safe and inexpensive and last 10–15 min each. The module entitled The Sound and Feel of Data represents axes and data points with pipe cleaners and coins, respectively, allowing for a discussion of data presentation and trends without reliance on visual signals. The Conductivity of Materials module tactilely introduces concepts of electron flow in metallic, semiconducting, and insulating materials using marbles, followed by a sound volume representation of the conductivity of everyday objects. The Optical Lenses module uses rope segments secured to a corkboard to trace tactile ray diagrams representing the concept of focusing, diverging, and aberration in optical lenses. Finally, the Chemistry and Physics of Heat module uses the dissolution of ammonium nitrate and sodium sulfate in sealed plastic tubes as well as the crystallization of sodium acetate to describe endothermic and exothermic processes. The modules were tested during an event attended by 38 participants with visual impairments; answers to learning assessment questions as well as pre- and post-module surveys suggest that we were successful at introducing scientific concepts and generating interest in science. This work provides new ways to introduce science that are applicable to all learners, visually impaired or not

The population genetic structure of a common tropical damselfish on the Great Barrier Reef and eastern Papua New Guinea

Understanding patterns of connectivity in marine species is vital for the management and conservation of marine biodiversity. Here, the population genetic structure of a common and abundant tropical reef damselfish, Pomacentrus amboinensis, is reported. Using nine polymorphic microsatellite loci, the genetic structure at both small (i.e., around Lizard Island, Great Barrier Reef [GBR]) and large (GBR and Papua New Guinea [PNG]) spatial and temporal scales (2–1,600 km; 28 days– 6 years; n = 1,119) was analyzed. Temporal analyses found no evidence of genetic differentiation within or between Lizard Island recruitment pulses (RST = -0.001, P = 0.788), or corresponding established adult populations separated by 6 years of sampling (RST = 0.003, P = 0.116). The spatial analysis revealed that P. amboinensis populations are largely panmictic on the GBR and eastern PNG (RST = 0.001, P = 0.913), the only genetic discontinuity being between Kimbe Bay to the north of PNG and all populations south of PNG (RST = 0.077, P\0.0001). Despite assumed high levels of self-recruitment based on previous tagging studies (15–60%), data presented here indicate that enough recruits are dispersing to impede the evolution of genetic structure over distances as great as 1,600 kms in this species. Data therefore indicate that the temporal genetic stability recorded here is maintained by high levels of gene flow

Genetic tools link long-term demographic and life-history traits of anemonefish to their anemone hosts

International audienceThe life-history traits and population dynamics of species are increasingly being attributed to the characteristics of their preferred habitats. While coral reef fish are often strongly associated with particular habitats, long-term studies establishing the demographic and life-history consequences of occupying different reef substrata are rare and no studies have monitored individuals in situ over their lifetime and determined the fate of their offspring. Here, we documented a quasi-turnover and local reproductive success for an entire population of orange clownfish (Amphiprion percula) from Kimbe Island, Papua New Guinea, by taking bi-annual samples of DNA over a 10-yr period (2003–2013). We compared demographic and life-history traits of individuals living on two host anemone species, Heteractis magnifica and Stichodactyla gigantea, including female size, adult continued presence (a proxy for relative longevity range), early post-settlement growth, the number of eggs per clutch and ‘local’ reproductive success (defined for each adult as the number of offspring returning to the natal population). Our results indicate that while the relative longevity of adults was similar on both host anemone species, females living in H. magnifica were larger than females in S. gigantea. However, despite females growing larger and producing more eggs on H. magnifica, we found that local reproductive success was significantly higher for clownfish living in S. gigantea. Life-history traits also exhibited local spatial variation, with higher local reproductive success recorded for adults living on S. gigantea on the eastern side of the island. Our findings support a ‘silver-spoon’ hypothesis that predicts individuals that are fortunate enough to recruit into good habitat and location will be rewarded with higher long-term reproductive success and will make a disproportionate contribution to population renewal