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Transmission of Ranavirus between Ectothermic Vertebrate Hosts  [PDF]
Roberto Brenes, Matthew J. Gray, Thomas B. Waltzek, Rebecca P. Wilkes, Debra L. Miller
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0092476
Abstract: Transmission is an essential process that contributes to the survival of pathogens. Ranaviruses are known to infect different classes of lower vertebrates including amphibians, fishes and reptiles. Differences in the likelihood of infection among ectothermic vertebrate hosts could explain the successful yearlong persistence of ranaviruses in aquatic environments. The goal of this study was to determine if transmission of a Frog Virus 3 (FV3)-like ranavirus was possible among three species from different ectothermic vertebrate classes: Cope’s gray treefrog (Hyla chrysoscelis) larvae, mosquito fish (Gambusia affinis), and red-eared slider (Trachemys scripta elegans). We housed individuals previously exposed to the FV3-like ranavirus with na?ve (unexposed) individuals in containers divided by plastic mesh screen to permit water flow between subjects. Our results showed that infected gray treefrog larvae were capable of transmitting ranavirus to na?ve larval conspecifics and turtles (60% and 30% infection, respectively), but not to fish. Also, infected turtles and fish transmitted ranavirus to 50% and 10% of the na?ve gray treefrog larvae, respectively. Nearly all infected amphibians experienced mortality, whereas infected turtles and fish did not die. Our results demonstrate that ranavirus can be transmitted through water among ectothermic vertebrate classes, which has not been reported previously. Moreover, fish and reptiles might serve as reservoirs for ranavirus given their ability to live with subclinical infections. Subclinical infections of ranavirus in fish and aquatic turtles could contribute to the pathogen’s persistence, especially when highly susceptible hosts like amphibians are absent as a result of seasonal fluctuations in relative abundance.
The behaviour of the recently described Rodrigues damselfish, Pomacentrus rodriguesensis
Emily Ruth Hardman, Reshad Jhangeer-Khan, Jean Stephen Jovani Raffin, Marie Sabrina Meunier, Sydney Perrine, Runolph Raffaut
Western Indian Ocean Journal of Marine Science , 2011,
Abstract: This was the first study to make preliminary observations on the behaviour of a recently described species, Pomacentrus rodriguesensis from the island of Rodrigues. P. rodriguesensis was observed to be solitary species with a preference for territories in live coral. Individuals fed using a combination of methods, feeding predominantly on plankton, but also occasionally on benthic algae. P. rodriguesensis was found to defend its territory against other individuals. Conspecifics elicited the majority of agonistic responses and P. rodriguesensis also acted aggressively towards benthic feeders such as Pomacentrus pikei and Stegastes limbatus. During summer, P. rodriguesensis also interacted with species of wrasse. It is suggested that the pattern of territoriality observed in P. rodriguesensis serves to reduce the loss of benthic algae to competitors and protect the nest from egg predators.
Spot the Difference: Mimicry in a Coral Reef Fish  [PDF]
Monica Gagliano, Martial Depczynski
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0055938
Abstract: Eyespots on the body of many animals have long been assumed to confer protection against predators, but empirical evidence has recently demonstrated that this may not always be the case and suggested that such markings may also serve other purposes. Clearly, this raises the unresolved question of what functions do these markings have and do they contribute to an individual’s evolutionary fitness in the wild. Here, we examined the occurrence of eyespots on the dorsal fin of a coral reef damselfish (Pomacentrus amboinensis), where these markings are typical of the juvenile stage and fade away as the fish approaches sexual maturation to then disappear completely in the vast majority of, but not all, adult individuals. By exploring differences in body shape among age and gender groups, we found that individuals retaining the eyespot into adulthood are all sexually mature males, suggesting that these eyespots may be an adult deceptive signal. Interestingly, the body shape of these individuals resembled more closely that of immature females than mature dominant males. These results suggest that eyespots have multiple roles and their functional significance changes within the lifetime of an animal from being a juvenile advertisement to a deceptive adult signal. Male removal experiments or colour manipulations may be necessary to establish specific functions.
Variability in Isotope Discrimination Factors in Coral Reef Fishes: Implications for Diet and Food Web Reconstruction  [PDF]
Alex S. J. Wyatt,Anya M. Waite,Stuart Humphries
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0013682
Abstract: Interpretation of stable isotope ratios of carbon and nitrogen (δ13C and δ15N) is generally based on the assumption that with each trophic level there is a constant enrichment in the heavier isotope, leading to diet-tissue discrimination factors of 3.4‰ for 15N (ΔN) and ~0.5‰ for 13C (ΔC). Diet-tissue discrimination factors determined from paired tissue and gut samples taken from 152 individuals from 26 fish species at Ningaloo Reef, Western Australia demonstrate a large amount of variability around constant values. While caution is necessary in using gut contents to represent diet due to the potential for high temporal variability, there were significant effects of trophic position and season that may also lead to variability in ΔN under natural conditions. Nitrogen enrichment increased significantly at higher trophic levels (higher tissue δ15N), with significantly higher ΔN in carnivorous species. Changes in diet led to significant changes in ΔN, but not tissue δ15N, between seasons for several species: Acanthurus triostegus, Chromis viridis, Parupeneus signatus and Pomacentrus moluccensis. These results confirm that the use of meta-analysis averages for ΔN is likely to be inappropriate for accurately determining diets and trophic relationships using tissue stable isotope ratios. Where feasible, discrimination factors should be directly quantified for each species and trophic link in question, acknowledging the potential for significant variation away from meta-analysis averages and, perhaps, controlled laboratory diets and conditions.
Comparative Phylogeography in Fijian Coral Reef Fishes: A Multi-Taxa Approach towards Marine Reserve Design
Joshua A. Drew,Paul H. Barber
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0047710
Abstract: Delineating barriers to connectivity is important in marine reserve design as they describe the strength and number of connections among a reserve's constituent parts, and ultimately help characterize the resilience of the system to perturbations at each node. Here we demonstrate the utility of multi-taxa phylogeography in the design of a system of marine protected areas within Fiji. Gathering mtDNA control region data from five species of coral reef fish in five genera and two families, we find a range of population structure patterns, from those experiencing little (Chrysiptera talboti, Halichoeres hortulanus, and Pomacentrus maafu), to moderate (Amphiprion barberi, Φst = 0.14 and Amblyglyphidodon orbicularis Φst = 0.05) barriers to dispersal. Furthermore estimates of gene flow over ecological time scales suggest species-specific, asymmetric migration among the regions within Fiji. The diversity among species-specific results underscores the limitations of generalizing from single-taxon studies, including the inability to differentiate between a species-specific result and a replication of concordant phylogeographic patterns, and suggests that greater taxonomic coverage results in greater resolution of community dynamics within Fiji. Our results indicate that the Fijian reefs should not be managed as a single unit, and that closely related species can express dramatically different levels of population connectivity.
Andirobin from X. moluccensis  [cached]
Chutima Jittaniyom,Damrong Sommit,Nongnuj Muangsin,Khanitha Pudhom
Acta Crystallographica Section E , 2012, DOI: 10.1107/s1600536812027705
Abstract: The title compound (systematic name: methyl 2-{(1R,2R)-2-[(1aS,4S,4aS,8aS)-4-(furan-3-yl)-4a-methyl-8-methylene-2-oxooctahydrooxireno[2,3-d]isochromen-7-yl]-2,6,6-trimethyl-5-oxocyclohex-3-en-1-yl}acetate), C27H32O7, was isolated from X. moluccensis seeds from Thailand. The conformations of the six-membered rings are distorted half-chair, chair and half-chair for the isolated cyclohexane, fused cyclohexane and lactone rings, respectively. In addition, the lactone ring bears in an equatorial orientation an essentially planar furan ring (r.m.s. deviation = 0.004 ), which forms an angle of 63.87 (13)° with the mean plane defined by the ten atoms of the two fused six-membered rings (r.m.s. deviation = 0.213 ). The absolute configuration was fixed on the basis of literature data.
A Global Estimate of the Number of Coral Reef Fishers  [PDF]
Louise S. L. Teh, Lydia C. L. Teh, U. Rashid Sumaila
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0065397
Abstract: Overfishing threatens coral reefs worldwide, yet there is no reliable estimate on the number of reef fishers globally. We address this data gap by quantifying the number of reef fishers on a global scale, using two approaches - the first estimates reef fishers as a proportion of the total number of marine fishers in a country, based on the ratio of reef-related to total marine fish landed values. The second estimates reef fishers as a function of coral reef area, rural coastal population, and fishing pressure. In total, we find that there are 6 million reef fishers in 99 reef countries and territories worldwide, of which at least 25% are reef gleaners. Our estimates are an improvement over most existing fisher population statistics, which tend to omit accounting for gleaners and reef fishers. Our results suggest that slightly over a quarter of the world’s small-scale fishers fish on coral reefs, and half of all coral reef fishers are in Southeast Asia. Coral reefs evidently support the socio-economic well-being of numerous coastal communities. By quantifying the number of people who are employed as reef fishers, we provide decision-makers with an important input into planning for sustainable coral reef fisheries at the appropriate scale.
Shifting from Right to Left: The Combined Effect of Elevated CO2 and Temperature on Behavioural Lateralization in a Coral Reef Fish  [PDF]
Paolo Domenici, Bridie J. M. Allan, Sue-Ann Watson, Mark I. McCormick, Philip L. Munday
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0087969
Abstract: Recent studies have shown that elevated CO2 can affect the behaviour of larval and juvenile fishes. In particular, behavioural lateralization, an expression of brain functional asymmetries, is affected by elevated CO2 in both coral reef and temperate fishes. However, the potentially interacting effects of rising temperatures and CO2 on lateralization are unknown. Here, we tested the combined effect of near-future elevated-CO2 concentrations (930 μatm) and temperature variation on behavioural lateralization of a marine damselfish, Pomacentrus wardi. Individuals exposed to one of four treatments (two CO2 levels and two temperatures) were observed in a detour test where they made repeated decisions about turning left or right. Individuals exposed to current CO2 and ambient temperature levels showed a significant right-turning bias at the population level. This biased was reversed (i.e. to the left side) in fish exposed to the elevated-CO2 treatment. Increased temperature attenuated this effect, resulting in lower values of relative lateralization. Consequently, rising temperature and elevated CO2 may have different and interactive effects on behavioural lateralization and therefore future studies on the effect of climate change on brain functions need to consider both these critical variables in order to assess the potential consequences for the ecological interactions of marine fishes.
The Role of Turtles as Coral Reef Macroherbivores  [PDF]
Christopher H. R. Goatley, Andrew S. Hoey, David R. Bellwood
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0039979
Abstract: Herbivory is widely accepted as a vital function on coral reefs. To date, the majority of studies examining herbivory in coral reef environments have focused on the roles of fishes and/or urchins, with relatively few studies considering the potential role of macroherbivores in reef processes. Here, we introduce evidence that highlights the potential role of marine turtles as herbivores on coral reefs. While conducting experimental habitat manipulations to assess the roles of herbivorous reef fishes we observed green turtles (Chelonia mydas) and hawksbill turtles (Eretmochelys imbricata) showing responses that were remarkably similar to those of herbivorous fishes. Reducing the sediment load of the epilithic algal matrix on a coral reef resulted in a forty-fold increase in grazing by green turtles. Hawksbill turtles were also observed to browse transplanted thalli of the macroalga Sargassum swartzii in a coral reef environment. These responses not only show strong parallels to herbivorous reef fishes, but also highlight that marine turtles actively, and intentionally, remove algae from coral reefs. When considering the size and potential historical abundance of marine turtles we suggest that these potentially valuable herbivores may have been lost from many coral reefs before their true importance was understood.
MAPPING OF CORAL REEF ECOSYSTEM IN THE NATUNA ISLANDS USING ALOS IMAGERY  [cached]
Suyarso,Yaya Ihya Ulumuddin,Bayu Prayuda
Journal of Coastal Development , 2011,
Abstract: The coral reef ecology of the Natuna Islands has been studied over 10 years. However, none of those studies produced a coral reef map. Maps of coral reef ecosystem are important for planning, management and monitoring tool. The present study integrates the 115 field data and the ALOS satellite data, using depth invariant index algorithm to generate coral reef ecosystem classes. Those classes are: life corals, dead coral and rubble aggregates, mixing of substrates and sand. The algorithm that composed of three visible bands is applicable at clear water rather than at turbid water environment. Hence, vegetation coverage as well as seagrass, seaweed and macro algae which are in small extent and usually covered by fine sand materials and associated with turbid water, cannot be classified.The aim of this research, which is funded by Critic Coremap – LIPI, is to produce map of coral reef ecosystem in the Natuna Islands.
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