599 research outputs found

    Differences in demographic traits of four butterflyfish species between two reefs of the Great Barrier Reef separated by 1,200 km

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    Author Posting. © The Author(s), 2011. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Coral Reefs 31 (2012): 169-177, doi:10.1007/s00338-011-0838-z.Many species demonstrate variation in life history attributes in response to gradients in environmental conditions. For fishes, major drivers of life history variation are changes in temperature and food availability. This study examined large-scale variation in the demography of four species of butterflyfishes (Chaetodon citrinellus, C. lunulatus, C. melannotus, and C. trifascialis) between two locations on Australia’s Great Barrier Reef (Lizard Island and One Tree Island, separated by approximately 1200km). Variation in age-based demographic parameters was assessed using the re-parameterised von Bertalanffy growth function. All species displayed measurable differences in body size between locations, with individuals achieving a larger adult size at the higher latitude site (One Tree Island) for three of the four species examined. Resources and abundances of the study species were also measured, revealing some significant differences between locations. For example, for C. trifascialis, there was no difference in its preferred resource or in abundance between locations, yet it achieved a larger body size at the higher latitude location, suggesting a response to temperature. For some species, resources and abundances did vary between locations, limiting the ability to distinguish between a demographic response to temperature as opposed to a response to food or competition. Future studies of life histories and demographics at large spatial scales will need to consider the potentially confounding roles of temperature, resource usage and availability, and abundance / competition in order to disentangle the effects of these environmental variables.This work was supported by a National Science Foundation (USA) Graduate Research Fellowship (MLB) and by PADI Project A.W.A.R.E. (MLB).2012-11-1

    Intestinal Microbiome Richness of Coral Reef Damselfishes (Actinopterygii: Pomacentridae)

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    Fish gastro-intestinal system harbors diverse microbiomes that affect the host's digestion, nutrition, and immunity. Despite the great taxonomic diversity of fish, little is understood about fish microbiome and the factors that determine its structure and composition. Damselfish are important coral reef species that play pivotal roles in determining algae and coral population structures of reefs. Broadly, damselfish belong to either of two trophic guilds based on whether they are planktivorous or algae-farming. In this study, we used 16S rRNA gene sequencing to investigate the intestinal microbiome of 5 planktivorous and 5 algae-farming damselfish species (Pomacentridae) from the Great Barrier Reef. We detected Gammaproteobacteria ASVs belonging to the genus Actinobacillus in 80% of sampled individuals across the 2 trophic guilds, thus, bacteria in this genus can be considered possible core members of pomacentrid microbiomes. Algae-farming damselfish had greater bacterial alpha-diversity, a more diverse core microbiome and shared 35 ± 22 ASVs, whereas planktivorous species shared 7 ± 3 ASVs. Our data also highlight differences in microbiomes associated with both trophic guilds. For instance, algae-farming damselfish were enriched in Pasteurellaceae, whilst planktivorous damselfish in Vibrionaceae. Finally, we show shifts in bacterial community composition along the intestines. ASVs associated with the classes Bacteroidia, Clostridia, and Mollicutes bacteria were predominant in the anterior intestinal regions while Gammaproteobacteria abundance was higher in the stomach. Our results suggest that the richness of the intestinal bacterial communities of damselfish reflects host species diet and trophic guild

    Epinephelus chlorostigma, Brownspotted Grouper

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    Epinephelus chlorostigma is a fairly widespread and relatively abundant species that inhabits reefs in both shallow and deep waters. There are signs of localised declines due to fishing effort in some areas, particularly in the Seychelles, and suspected declines in others (Indonesia). Catches of this species are generally low in comparison to other groupers in many parts of its range, which may be a function of its deeper depth preference. Population declines are not suspected on a global level at this time; therefore, it is listed as Least Concern. It is recommended that catches, particularly in areas where groupers are lumped, should be monitored carefully and frequently to provide more species-specific quantitative information

    Contrasting population genetic structure in three aggregating groupers (Percoidei: Epinephelidae) in the Indo-West Pacific: The importance of reproductive mode

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    Background: Understanding the factors shaping population genetic structure is important for evolutionary considerations as well as for management and conservation. While studies have revealed the importance of palaeogeographic changes in shaping phylogeographic patterns in multiple marine fauna, the role of reproductive behaviour is rarely considered in reef fishes. We investigated the population genetics of three commercially important aggregating grouper species in the Indo-West Pacific, namely the camouflage grouper Epinephelus polyphekadion, the squaretail coral grouper Plectropomus areolatus, and the common coral trout P. leopardus, with similar life histories but distinct spatio-temporal characteristics in their patterns of forming spawning aggregations. Results: By examining their mitochondrial control region and 9-11 microsatellite markers, we found an overarching influence of palaeogeographic events in the population structure of all species, with genetic breaks largely coinciding with major biogeographic barriers. The divergence time of major lineages in these species coincide with the Pleistocene glaciations. Higher connectivity is evident in E. polyphekadion and P. areolatus that assemble in larger numbers at fewer spawning aggregations and in distinctive offshore locations than in P. leopardus which has multiple small, shelf platform aggregations. Conclusions: While palaeogeographic events played an important role in shaping the population structure of the target species, the disparity in population connectivity detected may be partly attributable to differences in their reproductive behaviour, highlighting the need for more investigations on this characteristic and the need to consider reproductive mode in studies of connectivity and population genetics

    Fishes of the Cocos (Keeling) Islands: new records, community composition and biogeographic significance

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    The Cocos (Keeling) Islands comprise the most isolated oceanic atoll in the tropical Indian Ocean and are situated 1000 km south-west of Indonesia. The remoteness of the islands has shaped the composition of marine communities but also limited scientific research. This study summarises field research on the marine fishes of the Cocos (Keeling) Islands over the last 14 years (2001–2014). Sixty-seven new records (from 28 families) are described and raise the total number of known fishes to 602 species from 84 families. New records span a variety of body sizes (3 cm TL Gobiodon unicolor to 500 cm TL Rhincodon typus), were observed in all major habitats,and found at both the Southern Atoll and at North Keeling Island. Notable new records include first records for the families Alopiidae, Coryphaenidae, Eleotridae, Gempylidae, Istiophoridae, Molidae, Polymixiidae, Rhincodontidae, Sillaginidae and Xiphiidae. Sampling from pelagic and deepwater (60–300 m) reef environments significantly increased the number of species described from these habitats. New records include species that have dispersed more than 2500 km (Centropyge acanthops) and dispersal ability appears to explain the lack of syngnathids and the high representation of acanthurids and holocentrids in the community. Some of the Indian Ocean species that have colonised the Cocos (Keeling) Islands now co-occur with their Pacific Ocean sister species, increasing the potential for hybridisation. Although the fish community of the Cocos (Keeling) Island resembles that of the Indo-West Pacific, the isolation and co-occurrence of Indian and Pacific Ocean species distinguishes it from all other locations

    Feeding Strategies of Optaflexx on Growth Performance and Carcass Characteristics of Feedlot Steers

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    Live BW and carcass traits of steer calves were evaluated after feeding Optaflexx (200mg/day) for 35 days on an intermittent basis or continuously. The negative control consisted of 63 days on the same diet without Optaflexx, whereas the positive control consisted of Optaflexx supplemented daily during the last 35 days prior to harvest. The four-day intermittent treatment consisted of feeding Optaflexx for seven days, followed by four days of no Optaflexx, while the seven-day intermittent treatment consisted of seven days on Optaflexx, followed by seven days off. In both the four-day and seven-day intermittent treatments, cattle received Optaflexx for a total of 35 days. Regardless of the delivery pattern, feeding Optaflexx increased ADG, DMI, and live BW. Feeding 200 mg per steer daily of Optaflexx for a total of 35 days in either four-day or seven-day intermittent patterns was as effective but no more so as continuous feeding for a 35-day period

    Water Filtration Using Plant Xylem

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    Effective point-of-use devices for providing safe drinking water are urgently needed to reduce the global burden of waterborne disease. Here we show that plant xylem from the sapwood of coniferous trees – a readily available, inexpensive, biodegradable, and disposable material – can remove bacteria from water by simple pressure-driven filtration. Approximately 3 cm3 of sapwood can filter water at the rate of several liters per day, sufficient to meet the clean drinking water needs of one person. The results demonstrate the potential of plant xylem to address the need for pathogen-free drinking water in developing countries and resource-limited settings

    Feeding Strategies of Optaflexx on Growth Performance and Carcass Characteristics of Feedlot Steers

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    Live BW and carcass traits of steer calves were evaluated after feeding Optaflexx (200mg/day) for 35 days on an intermittent basis or continuously. The negative control consisted of 63 days on the same diet without Optaflexx, whereas the positive control consisted of Optaflexx supplemented daily during the last 35 days prior to harvest. The four-day intermittent treatment consisted of feeding Optaflexx for seven days, followed by four days of no Optaflexx, while the seven-day intermittent treatment consisted of seven days on Optaflexx, followed by seven days off. In both the four-day and seven-day intermittent treatments, cattle received Optaflexx for a total of 35 days. Regardless of the delivery pattern, feeding Optaflexx increased ADG, DMI, and live BW. Feeding 200 mg per steer daily of Optaflexx for a total of 35 days in either four-day or seven-day intermittent patterns was as effective but no more so as continuous feeding for a 35-day period
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