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Cyronak, T, Andersson AJ, Langdon C, Albright R, Bates NR, Caldeira K, Carlton R, Corredor JE, Dunbar RB, Enochs I, Erez J, Eyre BD, Gattuso JP, Gledhill D, Kayanne H, Kline DI, Koweek DA, Lantz C, Lazar B, Manzello D, McMahon A, Melendez M, Page HN, Santos IR, Schulz KG, Shaw E, Silverman J, Suzuki A, Teneva L, Watanabe A, Yamamoto S.  2018.  Taking the metabolic pulse of the world's coral reefs. Plos One. 13   10.1371/journal.pone.0190872   AbstractWebsite

Worldwide, coral reef ecosystems are experiencing increasing pressure from a variety of anthropogenic perturbations including ocean warming and acidification, increased sedimentation, eutrophication, and overfishing, which could shift reefs to a condition of net calcium carbonate (CaCO3) dissolution and erosion. Herein, we determine the net calcification potential and the relative balance of net organic carbon metabolism (net community production; NCP) and net inorganic carbon metabolism (net community calcification; NCC) within 23 coral reef locations across the globe. In light of these results, we consider the suitability of using these two metrics developed from total alkalinity (TA) and dissolved inorganic carbon (DIC) measurements collected on different spatiotemporal scales to monitor coral reef biogeochemistry under anthropogenic change. All reefs in this study were net calcifying for the majority of observations as inferred from alkalinity depletion relative to offshore, although occasional observations of net dissolution occurred at most locations. However, reefs with lower net calcification potential (i.e., lower TA depletion) could shift towards net dissolution sooner than reefs with a higher potential. The percent influence of organic carbon fluxes on total changes in dissolved inorganic carbon (DIC) (i.e., NCP compared to the sum of NCP and NCC) ranged from 32% to 88% and reflected inherent biogeochemical differences between reefs. Reefs with the largest relative percentage of NCP experienced the largest variability in seawater pH for a given change in DIC, which is directly related to the reefs ability to elevate or suppress local pH relative to the open ocean. This work highlights the value of measuring coral reef carbonate chemistry when evaluating their susceptibility to ongoing global environmental change and offers a baseline from which to guide future conservation efforts aimed at preserving these valuable ecosystems.

Crawley, A, Kline DI, Dunn S, Anthony K, Dove S.  2010.  The effect of ocean acidification on symbiont photorespiration and productivity in Acropora formosa. Global Change Biology. 16:851-863.   10.1111/j.1365-2486.2009.01943.x   AbstractWebsite

Ocean acidification is expected to lower the net accretion of coral reefs yet little is known about its effect on coral photophysiology. This study investigated the effect of increasing CO(2) on photosynthetic capacity and photoprotection in Acropora formosa. The photoprotective role of photorespiration within dinoflagellates (genus Symbiodinium) has largely been overlooked due to focus on the presence of a carbon-concentrating mechanism despite the evolutionary persistence of a Form II Rubisco. The photorespiratory fixation of oxygen produces phosphoglycolate that would otherwise inhibit carbon fixation though the Calvin cycle if it were not converted to glycolate by phosphoglycolate phosphatase (PGPase). Glycolate is then either excreted or dealt with by enzymes in the photorespiratory glycolate and/or glycerate pathways adding to the pool of carbon fixed in photosynthesis. We found that CO(2) enrichment led to enhanced photoacclimation (increased chlorophyll a per cell) to the subsaturating light levels. Light-enhanced dark respiration per cell and xanthophyll de-epoxidation increased, with resultant decreases in photosynthetic capacity (P(nmax)) per chlorophyll. The conservative CO(2) emission scenario (A1B; 600-790 ppm) led to a 38% increase in the P(nmax) per cell whereas the 'business-as-usual' scenario (A1F1; 1160-1500 ppm) led to a 45% reduction in PGPase expression and no change in P(nmax) per cell. These findings support an important functional role for PGPase in dinoflagellates that is potentially compromised under CO(2) enrichment.

Connell, SD, Kroeker KJ, Fabricius KE, Kline DI, Russell BD.  2013.  The other ocean acidification problem: CO2 as a resource among competitors for ecosystem dominance. Philosophical Transactions of the Royal Society B-Biological Sciences. 368   10.1098/rstb.2012.0442   AbstractWebsite

Predictions concerning the consequences of the oceanic uptake of increasing atmospheric carbon dioxide (CO2) have been primarily occupied with the effects of ocean acidification on calcifying organisms, particularly those critical to the formation of habitats (e. g. coral reefs) or their maintenance (e. g. grazing echinoderms). This focus overlooks direct and indirect effects of CO2 on non-calcareous taxa that play critical roles in ecosystem shifts (e. g. competitors). We present the model that future atmospheric [CO2] may act as a resource for mat-forming algae, a diverse and widespread group known to reduce the resilience of kelp forests and coral reefs. We test this hypothesis by combining laboratory and field CO2 experiments and data from 'natural' volcanic CO2 vents. We show that mats have enhanced productivity in experiments and more expansive covers in situ under projected near-future CO2 conditions both in temperate and tropical conditions. The benefits of CO2 are likely to vary among species of producers, potentially leading to shifts in species dominance in a high CO2 world. We explore how ocean acidification combines with other environmental changes across a number of scales, and raise awareness of CO2 as a resource whose change in availability could have wide-ranging community consequences beyond its direct effects.

Casas, V, Kline DI, Wegley L, Yu YN, Breitbart M, Rohwer F.  2004.  Widespread association of a Rickettsiales-like bacterium with reef-building corals. Environmental Microbiology. 6:1137-1148.   10.1111/j.1462-2920.2004.00647.x   AbstractWebsite

White band disease type I (WBD I) has been a major cause of the dramatic decline of Acroporid coral populations throughout the Caribbean during the last two decades, yet the aetiological agent of this disease is unknown. In this study, the bacterial communities associated with both healthy and diseased Acropora species were compared by 16S rDNA analyses. The bacterial communities of both healthy and diseased Acropora spp. were dominated by a single ribotype with 90% identity to a bacterium in the order Rickettsiales. Screening by nested PCR specific to the coral-associated Rickettsiales 1 (CAR1) bacterium showed that this microbe was widespread in both healthy and diseased A. cervicornis and A. palmata corals from 'healthy' (i.e. low WBD I incidence) and 'stressed' reefs (i.e. high WBD I incidence). These results indicate that there were no dramatic changes in the composition of the microbial community associated with WBD I. CAR1 was also associated with non-Acroporid corals of the Caribbean, as well as with two Acroporid corals native to the Pacific. CAR1 was not present in the water column. This bacterium was also absent from preserved Caribbean Acroporid samples collected between 1937 and 1980 before the outbreak of WBD I. These results suggest CAR1 is a relatively new bacterial associate of Acroporids and that a non-bacterial pathogen might be the cause of WBD I.

Calamia, MA, Kline DI, Kago S, Donovan K, Dulunaqio S, Tabaleka T, Mitchell BG.  2010.  Marine-based community conserved areas in Fiji: an example of indigenous governance and partnership. Indigenous peoples and conservation: from rights to resource management. ( Walker Painemilla K, Rylands AB, Woofter A, Hughers C, Eds.).:95-114., Arlington, VA.: Conservation International Abstract
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