| Popis: |
Increased atmospheric CO2 emissions are inducing changes in seawater carbon chemistry, lowering its pH. This phenomenon, known as ocean acidification, is happening at a faster rate in cold regions, i.e., polar and sub-polar waters. The larval development of a sub-Antarctic population from the species Arbacia dufresnei was studied at control (8.0) and lower pH (7.7 and 7.4) waters. A significant larval development delay was only recorded at pH 7.4, with no significant increase of abnormal forms. Larvae were isometric between pH treatments. Adult A.dufresnei seemed to present some degree of coelomic fluid buffer capacity and low seawater pH had no effect on the gonads and body wall metabolic status (RNA/DNA and carbonic anhydrase activity). Furthermore, spine regeneration was slightly affected. It is noteworthy that even at calcium carbonate saturation states lower than 1, skeleton deposition did occur, indicating calcification was most likely affected in an indirect way. In conclusion, both larvae and adults of A. dufresnei appeared rather resistant to acidification, at least at short term, reinforcing the idea of resilience of polar and sub-polar sea urchins towards acidification and underlining their potential to invade further Antarctic ecosystems. |
