Acid–base balance and metabolic response of the sea urchin Paracentrotus lividus to different seawater pH and temperatures

Purpose
In order to better understand if the metabolic responses of echinoids could be related to their acid–base status in an ocean acidification context, we studied the response of an intertidal sea urchin species, Paracentrotus lividus, submitted to low pH at two different temperatures.
Methods
Individuals were submitted to control (8.0) and low pH (7.7 and 7.4) at 10°C and 16°C (19 days). The relation between the coelomic fluid acid–base status, the RNA/DNA ratio of gonads and the individual oxygen uptake were studied.
Results
The coelomic fluid pH decreased with the aquarium seawater, independently of temperature, but this explained only 13% of the pH variation. The coelomic fluid showed though a partial buffer capacity that was not related to skeleton dissolution ([Mg2+] and [Ca2+] did not differ between pH treatments). There was an interaction between temperature and pH on the oxygen uptake (V O2) which was increased at pH 7.7 and 7.4 at 10°C in comparison with controls, but not at 16°C, indicating an upregulation of the metabolism at low temperature and pH. However, gonad RNA/DNA ratios did not differ according to pH and temperature treatments, indicating that even if maintenance of physiological activities has an elevated metabolic cost when individuals are exposed to stress, they are not directly affected during short-term exposure. Long-term studies are needed in order to verify if gonad production/growth will be affected by low pH seawaters exposure.

Catarino AI, Bauwens M & Dubois P., 2012. Acid–base balance and metabolic response of the sea urchin Paracentrotus lividus to different seawater pH and temperatures. Environmental Science and Pollution ResearchArticle (subscription required).

1 Response to “Acid–base balance and metabolic response of the sea urchin Paracentrotus lividus to different seawater pH and temperatures”


  1. 1 Aibrahim 28 February 2012 at 23:25

    as a specialist in acidification impact on physiology on marine organisms,stating this with experimental proofs , you are using the pH wont make impact, at this pH 7.7 and 7.4 (it should be a control) , at less than pH 6.8, it will get molecular and cellular impact,

    if you want to modulate or expect the change on the the ratio of DNA/RNA the acidity strength has to go below to the pH from 6.5 you will get mild change at this stage all cell organelles will respond mildly ,

    if you want trigger the ratio more effectively find the LC 50, and find the tolerance limit i confirmed that it will change drastically at pH 5.00,

    this is not an experiment even if you find the result /check the DNA / RNA ratio at pH 8.00 must have some changes than pH 7.4/ 7.7,

    i have supervised and completed some research projects, in this same aspect ,effect of environmental acidification on molecular modulations, including DNA / RNA ratios

    if you want to clarify contact me
    Prof A.Ibrahim Abdul Azeez
    Head department of biology
    Ocean acidification,climatic change and fisheries and aquaculture research lab
    Cuttington University
    Liberia
    00231 88 6646234
    iforibrahim@live.com


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