Sentences with phrase «calcification rates of»

Another important element affecting calcification rates of corals is the calcium carbonate saturation state of the mineral aragonite (Cohen et al., 2009; Gattuso et al., 1998; Marshall & Clode, 2002).

Our novel technique involved analysing coccolithophore skeletal remains and applying observations from modern specimens to estimate, for the first time, calcification rates of fossil coccolithophores.»

Moreover, using the average emission scenario (IS92a) of the Intergovernmental Panel on Climate Change, we predict that the calcification rate of scleractinian - dominated communities may decrease by 21 % between the pre-industrial period (year 1880) and the time at which pCO2 will double (year 2065).

Not exact matches

Emerging evidence for variability in the coral calcification response to acidification, geographical variation in bleaching susceptibility and recovery, responses to past climate change, and potential rates of adaptation to rapid warming supports an alternative scenario in which reef degradation occurs with greater temporal and spatial heterogeneity than current projections suggest.

Dr Sarah O'Dea, from Ocean and Earth Science at the University of Southampton and lead author of the study, says: «Our results show that climate change significantly altered coccolithophore calcification rates at the PETM and has the potential to be just as significant, perhaps even more so, today.

Previous studies showed that the coral calcification process has a diel rhythmic cycle of increasing rates towards midday, and then decreasing towards dusk (Gutner - Hoch et al., 2016; Schneider et al., 2009).

Hence, it could be suggested that the small differences in the calcification rates observed between 100 mg / L and 200 mg / L calcium additions during the day could be a result of relatively mediocre photosynthetic activities of the endo - symbionts, but this should be further studied.

The calcification rate values (µmol CaCO3 h − 1 cm − 2) were calculated according to the equation: Δ A T 2 ∗ V chamber − V coral T ∗ A coral where ΔAT is the difference in Total Alkalinity (AT) measured between the beginning and the end the incubation period, V is the volume of the chamber or the coral fragment, T is the duration of the incubation and A is the coral surface area.

In addition, reductions in calcification from lowered pH in surface waters could reduce phytoplankton sinking rates through loss of ballast (Hofmann and Schellnhuber, 2009), though this effect will depend on the ratio of the fraction of ballasted vs. un-ballasted fractions of the sinking POC.

Reduced food supply owing to lower POC fluxes could exacerbate these impacts because the metabolic cost of increased rates of calcification become greater as pH declines (Wood et al., 2008).

Following the concept that seawater Ωarag is a function of CO 3 2 − and calcium ion -LRB-[Ca2 +]-RRB- concentrations (Cyronak, Schulz & Jokiel, 2016), Longdon et al. (2000) and Marshall & Clode (2002) showed that exposing scleractinian corals to seawater with high calcium concentrations induces high calcification rates.

This decreases the rate and amount of calcification among many marine organisms that build external skeletons and shells, ranging from plankton to shellfish to reef - building corals.

In addition, the effect of the high calcium concentration was stronger in the calcification rates during day compared to the night (Fig. 2).

In the Nature study you state that previous work has not determined the impact of acidification on the ability of individual species to calcify because they measured net calcification (that is, gross calcification minus dissolution) thus failing to disentangle the relative contributions of gross calcification (the amount of carbonate deposited by an animal over time) and dissolution rates.

Since you state that a decrease in net calcification could result from a decrease in gross calcification, an increase in dissolution rates, or both, you distinguish between these responses and get to the conclusion that the impact of ocean acidification on a creature's net calcification may be largely controlled by the status of its protective organic cover and that the net slowdown in skeletal growth under increased CO2 occurs not because these organisms are unable to calcify, but rather because their unprotected skeleton is dissolving faster.

The study, which evaluated the calcification in the arteries of Egyptian mummies found high rates of atherosclerosis.

There are several feedbacks between decreasing the rate of calcification that organisms do in the ocean, and the carbon cycle.

The reef flat at Moorea displayed a higher rate of organic production and a lower rate of calcification compared to previous measurements carried out during austral summer.

Our data suggest that the rate of calcification during the last glacial maximum might have been 114 % of the preindustrial rate.

In addition, they state that there was «no significant correlation between calcification rate and seawater aragonite saturation (Ωarag)» and «no evidence of CO2 impact on bleaching.»

Lower calcification rates would reduce the alkalinity pump, reduce surface CO2 and increase the buffering capacity of surface waters.

Accordingly numerous studies have reported that greater rates of photosynthesis correlate with greater rates of calcification.

The team found that rates of reef calcification were 40 percent lower in 2008 and 2009 than they were during the same season in 1975 and 1976.

As such, ocean acidification could represent an abrupt climate impact when thresholds are crossed below which organisms lose the ability to create their shells by calcification, or pH changes affect survival rates (see the Extinctions section below for more discussion of these issues).

* The rising CO2 content of the atmosphere may induce very small changes in the well - buffered ocean chemistry (pH) that could slightly reduce coral calcification rates; but potential positive effects of hydrospheric CO2 enrichment may more than compensate for this modest negative phenomenon.

In order to establish a cause - and - effect relationship between acidification and decreased calcification, a team led by Carnegie's Ken Caldeira and including Jacob Silverman (the lead author) and Kenneth Schneider, formerly of Carnegie, compared measurements of the rate of calcification in one segment of Australia's Great Barrier Reef called Bird Island that were taken in between 1975 and 1979 to those made at the neighboring Lizard Island in 2008 and 2009.

Other potentially confounding factors are calcification, diagenesis, and the nature of the growth - rate - limiting factor, e.g. light vs nutrients.

All coastal engineering communities support intense metabolic processes, including high primary production, respiration and calcification rates, thereby affecting CO2, CO3 −, and alkalinity concentrations and surface water pH. However, many metabolically intense coastal habitats are experiencing global declines in their abundance at rates in excess of 1 % per year (Duarte et al. 2008; Ermgassen et al. 2013).

A growing number of studies have demonstrated adverse impacts on marine organisms, including decreases in rates of coral calcification, reduced ability of algae and zooplankton to maintain protective shells, and reduced survival of larval marine shellfish and fish [13], [14], [15].

Coastal ecosystems may show acidification or basification, depending on the balance between the invasion of coastal waters by anthropogenic CO2, watershed export of alkalinity, organic matter and CO2, and changes in the balance between primary production, respiration and calcification rates in response to changes in nutrient inputs and losses of ecosystem components.

Work from another team led by Caldeira found that rates of reef calcification were 40 percent lower in 2008 and 2009 than they were during the same season in 1975 and 1976.

In this study, averaged across all generation points, each coccolithophore cell increased its calcification rate (26 %) and calcium carbonate quota (26 %) in the future ocean treatment (figures 2a and 3a), and the total concentration of calcium carbonate in the culture (PIC l − 1) increased 18 % in the future ocean condition (table 4).

These responses include impacts on calcification rates [18,19], immune function [20], reproduction and carryover effects in larval and juvenile stages of invertebrates [21], enhanced productivity in phytobenthos [22 — 25] but reduced calcification and growth in calcareous algae [26 — 28].

These geologically ancient, long - lived, slow - growing and fragile reefs will suffer reduced calcification rates and, as the aragonite saturation horizon moves towards the ocean surface, large parts of the oceans will cease to support them by 2100 (Feely et al., 2004; Orr et al., 2005; Raven et al., 2005; Guinotte et al., 2006).