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| Moderate acidification affects growth but not survival of 6-month-old oysters |  |
| Amaral, V.; Cabral, H.N.; Bishop, M.J. (2012). Moderate acidification affects growth but not survival of 6-month-old oysters Aquat. Ecol. 46(1): 119-127. dx.doi.org/10.1007/s10452-011-9385-5 |
| In: Aquatic Ecology. Springer: Berlin. ISSN 1386-2588, meer |
| Trefwoorden |
Acidification; Loggen; Rotsige kusten; Sulphuric acid; PSE, Australia, New South Wales, Sydney Harbour; Marien; Brak water |
| Abstract |
Oyster populations periodically exposed to runoff from acid sulfate soils (ASS) are of depressed abundance and have fewer smaller individuals than unaffected populations, despite having similar recruitment levels to unaffected sites during dry periods. We examined how the timing and duration of exposure to ASS runoff influences the growth and survival of successfully settled oysters. We predicted that among 6-month-old oysters, growth and survival would be (1) lower among individuals continuously exposed to ASS-acidified waters than those that are episodically exposed, and (2) most negatively affected during rainfall events, which enhance transport of ASS runoff to estuaries. Six-month-old Sydney rock oysters, Saccostrea glomerata, were deployed at ASS-affected and unaffected sites within each of two south-east Australian estuaries. After 10 weeks, oysters were transplanted within and across sites in an estuary and maintained in situ for another 10 weeks. Oysters that remained for 20 weeks at ASS-affected sites grew at just over half the rate of oysters at reference sites. Oysters transplanted from acidified to reference sites grew more than oysters transplanted from reference to acidified sites or oysters that remained at reference sites. Unexpectedly, overall oyster mortality was low. Greater rainfall, and hence a lower pH, is likely to have accounted for the greater impact of acidification on growth during the second 10 weeks. Where oysters recruit to a 6-month age cohort, they may be able to tolerate subsequent, moderate, acidification events. Reduced growth during acidification periods may be offset by positive growth during intervening dry periods. |
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