Metabolically-induced pH fluctuations by some coastal calcifiers exceed projected 22nd century ocean acidification: a mechanism for differential susceptibility?
Anthropogenically-mediated decreases in pH, termed ocean acidification (OA), may be a major threat to marine organisms and communities. Research has focussed mainly on tropical coral reefs, but temperate reefs play a no less important ecological role in colder waters, where OA effects may first be manifest.
Calcium carbonate (CaCO3) sediment dissolution under elevated concentrations of carbon dioxide (CO2) and nitrate (NO3−)
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.
Ocean acidification hampers sperm-egg collisions, gamete fusion, and generation of Ca 2+ oscillations of a broadcast spawning bivalve, Tegillarca granosa
Although the effect of ocean acidification on fertilization success of marine organisms is increasingly well documented, the underlying mechanisms are not completely understood. The fertilization success of broadcast spawning invertebrates depends on successful sperm-egg collisions, gamete fusion, and standard generation of Ca2+ oscillations.
Expression of calcification and metabolism-related genes in response to elevated pCO2 and temperature in the reef-building coral Acropora millepora
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).
Impacts of groundwater discharge at Myora Springs (North Stradbroke Island, Australia) on the phenolic metabolism of eelgrass, Zostera muelleri, and grazing by the juvenile rabbitfish, Siganus fuscescens
Myora Springs is one of many groundwater discharge sites on North Stradbroke Island (Queensland, Australia). Here spring waters emerge from wetland forests to join Moreton Bay, mixing with seawater over seagrass meadows dominated by eelgrass, Zostera muelleri. We sought to determine how low pH / high CO2 conditions near the spring affect these plants and their interactions with the black rabbitfish (Siganus fuscescens), a co-occurring grazer. In paired-choice feeding trials S. fuscescens preferentially consumed Z. muelleri shoots collected nearest to Myora Springs.
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.
Long-term exposure to elevated carbon dioxide does not alter activity levels of a coral reef fish in response to predator chemical cues
ABSTRACT: Levels of dissolved carbon dioxide (CO2) projected to occur in the world's oceans in the near future have been reported to increase swimming activity and impair predator recognition in coral reef fishes. These behavioral alterations would be expected to have dramatic effects on survival and community dynamics in marine ecosystems in the future.
Upwelling modulation of functional traits of a dominant planktonic grazer during “warm-acid” El Niño 2015 in a year-round upwelling area of Humboldt Current
Climate change is expected to exacerbate upwelling intensity and natural acidification in Eastern Boundaries Upwelling Systems (EBUS). Conducted between January-September 2015 in a nearshore site of the northern Humboldt Current System directly exposed to year-round upwelling episodes, this study was aimed at assessing the relationship between upwelling mediated pH-changes and functional traits of the numerically dominant planktonic copepod-grazer Acartia tonsa (Copepoda).
Contrasting impact of future CO2 emission scenarios on the extent of CaCO3 mineral undersaturation in the Humboldt Current System
The eastern boundary upwelling systems are among those regions that are most vulnerable to an ocean acidification‐induced transition toward undersaturated conditions with respect to mineral CaCO3, but no assessment exists yet for the Humboldt Current System. Here we use a high‐resolution (∼7.5 km) regional ocean model to investigate past and future changes in ocean pH and CaCO3 saturation state in this system. We find that within the next few decades, the nearshore waters off Peru are projected to become corrosive year round with regard to aragonite, the more soluble form of CaCO3.
Response of subtropical coastal sediment systems of Okinawa, Japan, to experimental warming and high pCO2
Increasing seawater temperatures and CO2 levels associated with climate change affect the shallow marine ecosystem function. In this study, the effects of elevated seawater temperature and partial pressure of CO2 (pCO2) on subtropical sediment systems of mangrove, seagrass, and coral reef lagoon habitats of Okinawa, Japan, were examined.
Based upon surveys conducted in November 2012 and June 2013, the distribution and dynamics of aragonite saturation state ($Ømega$arag) were investigated in the southern Yellow Sea (SYS) of China. In summer, surface water $Ømega$arag ranged from 2.1–3.8 and enhanced biological production fueled by Changjiang River freshwater input increased $Ømega$arag to 3.8 in the southern SYS. However, subsurface water $Ømega$arag was \textless 2.0 in the central SYS.
High CO2 reduces the settlement of a spawning coral on three common species of crustose coralline algae
Concern about the impacts of ocean acidification (OA) on ecosystem function has prompted many studies to focus on larval recruitment, demonstrating declines in settlement and early growth at elevated CO2 concentrations. Since larval settlement is often driven by particular cues governed by crustose coralline algae (CCA), it is important to determine whether OA reduces larval recruitment with specific CCA and the generality of any effects.
A “core-top” screen for trace element proxies of environmental conditions and growth rates in the calcite skeletons of bamboo corals (Isididae)
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
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.
Increasing atmospheric CO2 can decrease the seawater pH and carbonate ions, which may adversely affect the larval survival of calcareous animals. In this study, we simulated future atmospheric CO2 concentrations (800, 1500, 2000 and 3000 $μ$atm) and examined the effects of ocean acidification on the embryonic and larval stage of an infaunal clam Paphia undulate. Significant decrease of hatching of P.
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.
Using the results from the NCAR CSM1.4-coupled global carbon cycle–climate model under the Intergovernmental Panel on Climate Change (IPCC) emission scenarios SRES A2 and B1, we estimated the effects of both global warming and ocean acidification on the future habitats of corals in the seas around Japan during this century. As shown by Yara et al.
Even when environmental data quantify the risks and benefits of delayed responses to rapid anthropogenic change, institutions rarely respond promptly. We propose that narratives complementing environmental datasets can motivate responsive environmental policy. To explore this idea, we relate a case study in which a narrative of economic loss due to regionally rapid ocean acidification-an anthropogenic change-helped connect knowledge with action.
Production of CO2-tolerant microalgae have received much attention as well as physicochemical fixation of CO2 in industrial flue gas. Although many microalgae that are tolerant to high levels of CO2 have been found and evaluated, the CO2 concentration for their good growth is generally lower than their maximum tolerable CO2 level. In the present study, we attempted to isolate microalgae capable of growing in high levels of CO2 (high-level-CO2-preferring microalgae, HCP-microalgae). We used a CO2-permeable polystyrene bottle for the enrichment of HCP-microalgae in environmental samples.
Ocean acidification is expected to negatively impact many calcifying marine organisms by impairing their ability to build their protective shells and skeletons, and by causing dissolution and erosion. Here we investigated the large predatory “triton shell” gastropod Charonia lampas in acidified conditions near CO2 seeps off Shikine-jima (Japan) and compared them with individuals from an adjacent bay with seawater pH at present-day levels (outside the influence of the CO2 seep).