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Reimer J.D.,University of Ryukyus | Albinsky D.,University of Ryukyus | Yang S.-Y.,University of Ryukyus | Lorion J.,University of Ryukyus | Lorion J.,Palau International Coral Reef Center
Marine Biodiversity | Year: 2014

Palau is world famous for its relatively pristine and highly diverse coral reefs, yet for many coral reef invertebrate taxa, few data exist on their diversity in this Micronesian country. One such taxon is the Zoantharia, an order of benthic cnidarians within the Class Anthozoa (Subclass Hexacorallia) that are commonly found in shallow subtropical and tropical waters. Here, we examine the species diversity of zoanthids in Palau for the first time, based on shallow-water (<35 m) scuba surveys and morphological identification to create a preliminary zoanthid species list for Palau. Our results indicated the presence of nine zoanthid species in Palau (Zoanthus sansibaricus, Z. gigantus, Palythoa tuberculosa, P. mutuki, P. heliodiscus, Palythoa cf. toxica, Epizoanthus illoricatus, Parazoanthus sp., Microzoanthus kagerou), apparently slightly more than have been recently observed in nearby Guam, Saipan, and the Ogasawara Islands. Additionally, it appears that some zoanthid species that have been observed to be co-occurring in the fringing reefs of Okinawa may inhabit different locations in the better developed reefs of Palau. © 2013 Senckenberg Gesellschaft für Naturforschung and Springer-Verlag Berlin Heidelberg. Source

Shamberger K.E.F.,Woods Hole Oceanographic Institution | Cohen A.L.,Woods Hole Oceanographic Institution | Golbuu Y.,Palau International Coral Reef Center | McCorkle D.C.,Woods Hole Oceanographic Institution | And 2 more authors.
Geophysical Research Letters | Year: 2014

Anthropogenic carbon dioxide emissions are acidifying the oceans, reducing the concentration of carbonate ions ([CO3 2-]) that calcifying organisms need to build and cement coral reefs. To date, studies of a handful of naturally acidified reef systems reveal depauperate communities, sometimes with reduced coral cover and calcification rates, consistent with results of laboratory-based studies. Here we report the existence of highly diverse, coral-dominated reef communities under chronically low pH and aragonite saturation state (Ωar). Biological and hydrographic processes change the chemistry of the seawater moving across the barrier reefs and into Palau's Rock Island bays, where levels of acidification approach those projected for the western tropical Pacific open ocean by 2100. Nevertheless, coral diversity, cover, and calcification rates are maintained across this natural acidification gradient. Identifying the combination of biological and environmental factors that enable these communities to persist could provide important insights into the future of coral reefs under anthropogenic acidification. ©2013. American Geophysical Union. All Rights Reserved. Source

Lindfield S.J.,University of Western Australia | Lindfield S.J.,Palau International Coral Reef Center | Harvey E.S.,Curtin University Australia | Halford A.R.,Kensington | McIlwain J.L.,Curtin University Australia
Coral Reefs | Year: 2016

Coral reefs are subjected to unprecedented levels of disturbance with population growth and climate change combining to reduce standing coral cover and stocks of reef fishes. Most of the damage is concentrated in shallow waters (<30 m deep) where humans can comfortably operate and where physical disturbances are most disruptive to marine organisms. Yet coral reefs can extend to depths exceeding 100 m, potentially offering refuge from the threats facing shallower reefs. We deployed baited remote underwater stereo-video systems (stereo-BRUVs) at depths of 10–90 m around the southern Mariana Islands to investigate whether fish species targeted by fishing in the shallows may be accruing benefits from being at depth. We show that biomass, abundance and species richness of fishery-targeted species increased from shallow reef areas to a depth of 60 m, whereas at greater depths, a lack of live coral habitat corresponded to lower numbers of fish. The majority of targeted species were found to have distributions that ranged from shallow depths (10 m) to depths of at least 70 m, emphasising that habitat, not depth, is the limiting factor in their vertical distribution. While the gradient of abundance and biomass versus depth was steepest for predatory species, the first species usually targeted by fishing, we also found that fishery-targeted herbivores prevailed in similar biomass and species richness to 60 m. Compared to shallow marine protected areas, there was clearly greater biomass of fishery-targeted species accrued in mesophotic depths. Particularly some species typically harvested by depth-limited fishing methods (e.g., spearfishing), such as the endangered humphead wrasse Cheilinus undulatus, were found in greater abundance on deeper reefs. We conclude that mesophotic depths provide essential fish habitat and refuge for fishery-targeted species, representing crucial zones for fishery management and research into the resilience of disturbed coral reef ecosystems. © 2015, Springer-Verlag Berlin Heidelberg. Source

Mumby P.J.,University of Queensland | Bejarano S.,University of Queensland | Golbuu Y.,Palau International Coral Reef Center | Steneck R.S.,University of Maine, United States | And 3 more authors.
Coral Reefs | Year: 2013

A process-orientated understanding of ecosystems usually starts with an exploratory analysis of empirical relationships among potential drivers and state variables. While relationships among herbivory, algal cover, and coral recruitment, have been explored in the Caribbean, the nature of such relationships in the Pacific appears to be variable or unclear. Here, we examine potential drivers structuring the benthos and herbivorous fish assemblages of outer-shelf reefs in Micronesia (Palau, Guam and Pohnpei). Surveys were stratified by wave exposure and protection from fishing. High biomass of most herbivores was favoured by high wave exposure. High abundance of large-bodied scarids was associated with low turf abundance, high coral cover, and marine reserves. The remaining herbivores were more abundant in reefs with low coral cover, possibly because space and hence food limitation occur in high-coral-cover reefs. Rugosity had no detectable effect on herbivorous fish abundance once differences in exposure and coral cover were accounted for. At identical depths, high wave exposure was associated with greater volumes (cover × canopy height) of macroalgae and algal turfs, which most likely resulted from high primary productivity driven by flow. In exposed areas, macroalgal cover declined as the acanthurid biomass increased. The volume of algal turfs was negatively associated with coral cover and herbivore biomass. In turn, high coral cover and herbivore biomass are likely to intensify grazing. The density of juvenile corals was variable where macroalgal cover was low but was confined to lower densities where macroalgal cover was high. High coral cover and density of juvenile corals were favoured in sheltered habitats. While a weak positive relationship was found between scarid biomass and juvenile coral density, we hypothesise that high scarid densities may hinder juvenile density through increased corallivory. New hypotheses emerged that will help clarify the role of acanthurids, wave exposure, and corallivory in driving the recovery of Pacific coral communities. © 2012 Springer-Verlag Berlin Heidelberg. Source

Golbuu Y.,Palau International Coral Reef Center | Friedlander A.M.,U.S. Geological Survey
Estuarine, Coastal and Shelf Science | Year: 2011

In Palau, Ngerumekaol and Ebiil Channels are spawning aggregation sites that have been protected from fishing since 1976 and 2000, respectively. Groupers and other targeted fisheries species were monitored monthly over a 1.5 year period at these two spawning aggregations and two nearby exploited reference sites where grouper formerly aggregated to spawn. At the protected aggregation sites, three grouper species (Plectropomus areolatus, Epinephelus polyphekadion, and Epinephelus fuscoguttatus) accounted for 78% of the abundance and 85% of the biomass of all resource species surveyed but comprised <1% of the total abundance and biomass at reference sites not protected from fishing that formally harbored spawning aggregations. Abundance and biomass of grouper species pooled were 54% and 72% higher, respectively, at Ngerumekaol compared to Ebiil. Comparisons with data from the same locations in 1995-1996 showed order of magnitude declines in abundance of E. polyphekadion at both locations. The lower numbers of E. fuscoguttatus and the near absence of E. polyphekadion at Ebiil may reflect the effects of previous and current overexploitation. © 2011 Elsevier Ltd. Source

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