33 results
 Pacific Data Hub

Ocean acidification (OA), attributed to the sequestration of atmospheric carbon dioxide (CO2) into the surface ocean, and coastal eutrophication, attributed in part to land-use change and terrestrial runoff of fertilizers, have received recent attention in an experimental framework examining the effects of each on coral reef net ecosystem calcification (Gnet). However, OA and eutrophication in conjunction have yet to receive attention from the perspective of coral reef sediment dissolution.

 Pacific Data Hub

Declining health of scleractinian corals in response to deteriorating environmental conditions is widely acknowledged, however links between physiological and functional genomic responses of corals are less well understood. Here we explore growth and the expression of 20 target genes with putative roles in metabolism and calcification in the branching coral, Acropora millepora, in two separate experiments: 1) elevated pCO2 (464, 822, 1187 and 1638 $μ$atm) and ambient temperature (27 °C), and 2) elevated pCO2 (490 and 822 $μ$atm) and temperature (28 and 31 °C).

 Pacific Data Hub

Ocean acidification represents a key threat to coral reefs by reducing the calcification rate of the major reef framework builders. In addition, acidification is likely to affect the important relationship between corals and their symbiotic dinoflagellates, and on the productivity of this association. However, little is known about how acidification impacts on the physiology of key reef builders and how acidification interacts with warming.

 Pacific Data Hub

We test for trace element proxies in the high-magnesium calcite fraction of bamboo coral internodes by comparing environmental conditions and growth rates to the specimen-mean compositions of 73 corals that were live-caught at depths ranging from 3 to 3950 m and collected from habitats ranging from tropical coral reefs to the Antarctic slope.Comparisons were done at a large geographic scale (LGS) and for a well sampled area south of Australia, across depths at a single site, in order to help separate the effects of environmental variables that co-vary at one spatial scale, but not the other

 Pacific Data Hub

Ocean acidification and warming are predicted to affect the ability of marine bivalves to build their shells, but little is known about the underlying mechanisms. Shell formation is an extremely complex process requiring a detailed understanding of biomineralization processes. Sodium incorporation into the shells would increase if bivalves rely on the exchange of Na+/H+ to maintain homeostasis for shell formation, thereby shedding new light on the acid-base and ionic regulation at the calcifying front.

 Pacific Data Hub

There is a long history of examining the impacts of nutrient pollution and pH on coral reefs. However, little is known about how these two stressors interact and influence coral reef ecosystem functioning. Using a six-week nutrient addition experiment, we measured the impact of elevated nitrate (NO−3) and phosphate (PO3−4) on net community calcification (NCC) and net community production (NCP) rates of individual taxa and combined reef communities.

 Pacific Data Hub

With respect to their sensitivity to ocean acidification, calcifiers such as the coccolithophore Emiliania huxleyi have received special attention, as the process of calcification seems to be particularly sensitive to changes in the marine carbonate system. For E. huxleyi, apparently conflicting results regarding its sensitivity to ocean acidification have been published (Iglesias-Rodriguez et al., 2008a; Riebesell et al., 2000). As possible causes for discrepancies, intra-specific variability and different effects of CO2 manipulation methods, i.e.

 Pacific Data Hub

Skeletal growth records in annually banded massive coral skeletons are an under-exploited archive of coral responses to environmental changes. Average linear extension and calcification rates in Indo-Pacific Porites are linearly related to average water temperatures through 23 to 30¯C. Assessing long-term trends in Porites extension and density requires caution as there is evidence of an age effect whereby in earlier growth years corals will tend to extend less and form a higher density skeleton than in later years. This does not appear to affect calcification rates.

 Pacific Data Hub

Due to the elevated atmospheric carbon dioxide, ocean acidification (OA) has recently emerged as a research theme in marine biology due to an expected deleterious effect of altered seawater chemistry on calcification. A system simulating future OA scenario is crucial for OA-related studies. Here, we designed an OA-simulated system (OASys) with three solenoid-controlled CO2 gas channels. The OASys can adjust the pH of the seawater by bubbling CO2 gas into seawaters via feedback systems.

 Pacific Data Hub

Anthropogenically-modulated reductions in pH, termed ocean acidification, could pose a major threat to the physiological performance, stocks, and biodiversity of calcifiers and may devalue their ecosystem services. Recent debate has focussed on the need to develop approaches to arrest the potential negative impacts of ocean acidification on ecosystems dominated by calcareous organisms. In this study, we demonstrate the role of a discrete (i.e.

 Pacific Data Hub

Marine acidification will be an important environmental problem in the near future as a result of persistent emissions of CO2 and dissolution into seawater. In this study, we found that calcification and respiration of the Zhikong scallop (Chlamys farreri) are likely to be severely affected by increasing acidification. Calcification and respiration significantly declined as pH decreased. The calcification rate decreased by 33% when the pH of water was 7.9 compared with a pH of 8.1, and decreased close to 0 when the pH was reduced to 7.3.

 Pacific Data Hub

The effects of elevated CO2 and temperature on photosynthesis and calcification in the calcifying algae Halimeda macroloba and Halimeda cylindracea and the symbiont-bearing benthic foraminifera Marginopora vertebralis were investigated through exposure to a combination of four temperatures (28°C, 30°C, 32°C, and 34°C) and four CO2 levels (39, 61, 101, and 203 Pa; pH 8.1, 7.9, 7.7, and 7.4, respectively). Elevated CO2 caused a profound decline in photosynthetic efficiency (FV : FM), calcification, and growth in all species. After five weeks at 34°C under all CO2 levels, all species died.

 Pacific Data Hub

The cheilostome bryozoan Melicerita chathamensis from the continental shelf around southern New Zealand is unusual in having macroscopic annual growth checks. It thus presents an opportunity to examine annual variations in age, growth, calcification and carbonate mineralogy in a temperate bryozoan. Forty-one colonies dredged south of Snares Islands, New Zealand (47° 49.537′S, 166° 45.910′E, 166 m water depth, 2 February 2008) ranged from 2 to 9 years old and were up to 40 mm long.

 Pacific Data Hub

Several studies have demonstrated that shellfish calcification rate has been impacted by ocean acidification. However, the carbonate system variables responsible for regulating calcification rate are controversial. To distinguish the key variables, we manipulated a seawater carbonate system by regulating seawater pH and dissolved inorganic carbon (DIC). Calcification rates of juvenile blue mussel (Mytilus edulis) and Zhikong scallop (Chlamys farreri) were measured in different carbonate systems.

 Pacific Data Hub

Cryptic colouration in crustaceans, important for both camouflage and visual communication, is achieved through physiological and morphological mechanisms that are sensitive to changes in environmental conditions. Consequently, ocean warming and ocean acidification can affect crustaceans' biophotonic appearance and exoskeleton composition in ways that might disrupt colouration and transparency.

 Pacific Data Hub

The impact of ocean acidification (OA) on coral calcification, a subject of intense current interest, is poorly understood in part because of the presence of symbionts in adult corals. Early life history stages of Acropora spp. provide an opportunity to study the effects of elevated CO2 on coral calcification without the complication of symbiont metabolism.

 Pacific Data Hub

Ocean acidification is a threat to marine ecosystems globally. In shallow-water systems, however, ocean acidification can be masked by benthic carbon fluxes, depending on community composition, seawater residence time, and the magnitude and balance of net community production (NCP) and calcification (NCC). Here, we examine how six benthic groups from a coral reef environment on Heron Reef (Great Barrier Reef, Australia) contribute to changes in the seawater aragonite saturation state ($Ømega$a).

 Pacific Data Hub

Body size has large effects on organism physiology, but these effects remain poorly understood in modular animals with complex morphologies. Using two trials of a ∼24 day experiment conducted in 2014 and 2015, we tested the hypothesis that colony size of the coral Pocillopora verrucosa affects the response of calcification, aerobic respiration and gross photosynthesis to temperature (∼26.5 and ∼29.7°C) and PCO2  (∼40 and ∼1000 µatm). Large corals calcified more than small corals, but at a slower size-specific rate; area-normalized calcification declined with size.

 Pacific Data Hub

Background Recent reviews suggest that the warming and acidification of ocean surface waters predicated by most accepted climate projections will lead to mass mortality and declining calcification rates of reef-building corals. This study investigates the use of modeling techniques to quantitatively examine rates of coral cover change due to these effects. Methodology/Principal Findings Broad-scale probabilities of change in shallow-water scleractinian coral cover in the Hawaiian Archipelago for years 2000–2099 A.D.

 Pacific Data Hub

Corals build their skeletons using extracellular calcifying fluid located in the tissue-skeleton interface. However, the mechanism by which corals control the transport of calcium and other ions from seawater and the mechanism of constant alkalization of calcifying fluid are largely unknown. To address these questions, we performed direct pH imaging at calcification sites (subcalicoblastic medium, SCM) to visualize active pH upregulation in live aposymbiotic primary coral polyps treated with HCl-acidified seawater.