Effects of low pH and feeding on calcification rates of the cold-water coral Desmophyllum dianthus

Cold-Water Corals (CWCs), and most marine calcifiers, are especially threatened by ocean acidification (OA) and the decrease in the carbonate saturation state of seawater. The vulnerability of these organisms, however, also involves other global stressors like warming, deoxygenation or changes in sea surface productivity and, hence, food supply via the downward transport of organic matter to the deep ocean. This study examined the response of the CWC Desmophyllum dianthus to low pH under different feeding regimes through a long-term incubation experiment. For this experiment, 152 polyps were incubated at pH 8.1, 7.8, 7.5 and 7.2 and two feeding regimes for 14 months. Mean calcification rates over the entire duration of the experiment ranged between −0.3 and 0.3 mg CaCO3 g−1d−1. Polyps incubated at pH 7.2 were the most affected and 30% mortality was observed in this treatment. In addition, many of the surviving polyps at pH 7.2 showed negative calcification rates indicating that, in the long term, CWCs may have difficulty thriving in such aragonite undersaturated waters. The feeding regime had a significant effect on skeletal growth of corals, with high feeding frequency resulting in more positive and variable calcification rates. This was especially evident in corals reared at pH 7.5 (ΩA = 0.8) compared to the low frequency feeding treatment. Early life-stages, which are essential for the recruitment and maintenance of coral communities and their associated biodiversity, were revealed to be at highest risk. Overall, this study demonstrates the vulnerability of D. dianthus corals to low pH and low food availability. Future projected pH decreases and related changes in zooplankton communities may potentially compromise the viability of CWC populations.

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Peer Review #2 of "Vertical and horizontal distribution of Desmophyllum dianthus in Comau Fjord, Chile: a cold-water coral thriving at low pH (v0.1)"

10.7287/peerj.194v0.1/reviews/2 ◽

2013 ◽

Author(s):

A Freiwald

Keyword(s):

Peer Review ◽

Cold Water ◽

Horizontal Distribution ◽

Low Ph ◽

Vertical And Horizontal Distribution ◽

Desmophyllum Dianthus ◽

Water Coral

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Nordic Seas Acidification

10.5194/bg-2020-339 ◽

2020 ◽

Author(s):

Filippa Fransner ◽

Friederike Fröb ◽

Jerry Tjiputra ◽

Melissa Chierici ◽

Agneta Fransson ◽

...

Keyword(s):

Barents Sea ◽

Cold Water ◽

Deep Ocean ◽

Case Scenario ◽

Worst Case ◽

Saturation State ◽

Nordic Seas ◽

Model Studies ◽

Deep Waters ◽

Anthropogenic Co2

Abstract. Being windows to the deep ocean, the Nordic Seas play an important role in transferring anthropogenic carbon, and thus ocean acidification, to the abyss. Due to its location in high latitudes, it is further more sensitive to acidification compared with many other oceanic regions. Here we make a detailed investigation of the acidification of the Nordic Seas, and its drivers, since pre-Industrial to 2100 by using in situ measurements, gridded climatological data, and simulations from one Earth System Model (ESM). In the last 40 years, pH has decreased by 0.11 units in the Nordic Seas surface waters, a change that is twice as large as that between 1850–1980. We find that present trends are larger than expected from the increase in atmospheric CO2 alone, which is related to a faster increase in the seawater pCO2 compared with that of the atmosphere, i.e. a weakening of the pCO2 undersaturation of the Nordic Seas. The pH drop, mainly driven by an uptake of anthropogenic CO2, is significant all over the Nordic Seas, except for in the Barents Sea Opening, where it is counteracted by a significant increase in alkalinity. We also find that the acidification signal penetrates relatively deep, in some regions down to 2000 m. This has resulted in a significant decrease in the aragonite saturation state, which approaches undersaturation at 1000–2000 m in the modern ocean. Future scenarios suggest an additional drop of 0.1–0.4 units, depending on the emission scenario, in surface pH until 2100. In the worst case scenario, RCP8.5, the entire water column will be undersaturated with respect to aragonite by the end of the century, threatening Nordic Seas cold-water corals and their ecosystems. The model simulations suggest that aragonite undersaturation can be avoided at depths where the majority of the cold-water corals live in the RCP2.6 and RCP4.5 scenarios. As these results are based on one model only, we request additional observational and model studies to better quantify the transfer of anthropogenic CO2 to deep waters and its effect on future pH in the Nordic Seas.

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Physiological characteristics of rats and ground squirrels during prolonged lethargic hypothermia

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1960.199.3.467 ◽

1960 ◽

Vol 199 (3) ◽

pp. 467-471 ◽

Cited By ~ 22

Author(s):

V. Popovic

Keyword(s):

Blood Pressure ◽

Body Temperature ◽

Arterial Blood Pressure ◽

Cold Water ◽

Physiological State ◽

Low Ph ◽

Ground Squirrels ◽

Adult Rats ◽

Arterial Blood

After intensive cooling, rats can be maintained at constant body temperature during several hours in a cylinder surrounded by cold water. The rats live in lethargic hypothermia at a body temperature of 15°C for 8–10 hours but can recover only if the hypothermia has not lasted more than 5.5 hours, average time of ‘biological survival.’ After 6 or more hours at 15°C adult rats showed irreversible hemoconcentration, hypoglycemia, drop in arterial blood pressure and low pH of the blood, but no change in pulse rate. Artificially cooled ground squirrels survived 110 hours at a body temperature of 10°C, ‘biological survival’ time being only 75 hours. Hemoconcentration, low arterial blood pressure and hypoglycemia have also been found in lethargic ground squirrels during the last part of survival. They cannot be rescued by rewarming. The deeply cooled animal with stabilized temperature is in a physiological state that changes with time and ultimately leads to death. A recovery prognosis during long-term hypothermia has been attempted, and the cause of death has been discussed.

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Peer Review #1 of "Effects of low pH and feeding on calcification rates of the cold-water coral Desmophyllum dianthus (v0.1)"

10.7287/peerj.8236v0.1/reviews/1 ◽

2020 ◽

Keyword(s):

Peer Review ◽

Cold Water ◽

Low Ph ◽

Desmophyllum Dianthus ◽

Water Coral

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Peer Review #2 of "Effects of low pH and feeding on calcification rates of the cold-water coral Desmophyllum dianthus (v0.1)"

10.7287/peerj.8236v0.1/reviews/2 ◽

2020 ◽

Keyword(s):

Peer Review ◽

Cold Water ◽

Low Ph ◽

Desmophyllum Dianthus ◽

Water Coral

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Peer Review #1 of "Vertical and horizontal distribution of Desmophyllum dianthus in Comau Fjord, Chile: a cold-water coral thriving at low pH (v0.1)"

10.7287/peerj.194v0.1/reviews/1 ◽

2013 ◽

Keyword(s):

Peer Review ◽

Cold Water ◽

Horizontal Distribution ◽

Low Ph ◽

Vertical And Horizontal Distribution ◽

Desmophyllum Dianthus ◽

Water Coral

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CARINA oxygen data in the Atlantic Ocean

Earth System Science Data ◽

10.5194/essd-1-87-2009 ◽

2009 ◽

Vol 1 (1) ◽

pp. 87-100 ◽

Cited By ~ 10

Author(s):

I. Stendardo ◽

N. Gruber ◽

A. Körtzinger

Keyword(s):

Atlantic Ocean ◽

North Atlantic ◽

Deep Ocean ◽

Saturation State ◽

The North ◽

Sample Density ◽

The Individual ◽

High Level ◽

Oxygen Measurements

Abstract. In the CARINA (Carbon dioxide in the Atlantic Ocean) project, a new dataset with many previously unpublished hydrographic data from the Atlantic, Arctic and Southern Ocean was assembled and subjected to careful quality control (QC) procedures. Here, we present the dissolved oxygen measurements in the Atlantic region of the dataset and describe in detail the secondary QC procedures that aim to ensure that the data are internally consistent. This is achieved by a cross-over analysis, i.e. the comparison of deep ocean data at places that were sampled by different cruises at different times. Initial adjustments to the individual cruises were then determined by an inverse procedure that computes a set of adjustments that requires the minimum amount of adjustment and at the same time reduces the offsets in an optimal manner. The initial adjustments were then reviewed by the CARINA members, and only those that passed the following two criteria were adopted: (i) the region is not subject to substantial temporal variability, and (ii) the adjustment must be based on at least three stations from each cruise. No adjustment was recommended for cruises that did not fit these criteria. The final CARINA-Oxygen dataset has 103414 oxygen samples from 9491 stations obtained during 98 cruises covering three decades. The sampling density of the oxygen data is particularly good in the North Atlantic north of about 40° N especially after 1987. In contrast, the sample density in the South Atlantic is much lower. Some cruises appear to have poor data quality, and were subsequently omitted from the adjusted dataset. Of the data included in the adjusted dataset, 20% were adjusted with a mean adjustment of 2%. Due to the achieved internal consistency, the resulting product is well suited to produce an improved climatology or to study long-term changes in the oxygen content of the ocean. However, the adjusted dataset is not necessarily better suited than the unadjusted data to address questions that require a high level of accuracy, such as the computation of the saturation state.

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