Potential for acclimation of banded-dye murex, Hexaplex trunculus (Linnaeus, 1758) after long-term exposure to low pH

• Previous work on ocean acidifi cation highlighted contrasting response between marine species and population. This so-called species-specifi c response was hypothesized to be partly a consequence of local adaptation to the present range of natural variability in the carbonate chemistry. Under that hypothesis, species tolerance threshold should be correlated to its environmental pH niche. This paper aims to evaluate shell growth rate of Hexaplex trunculus, an important predatory gastropod in benthic communities of Mali Ston Bay. A long-term experiment (310 days) was designed to test a range of pH treatments covering present and future pH levels relevant in the context of future ocean acidification (7.95-7.22 pHT) at the sampling site. Sex had an effect on the shell growth rate irrespective of pH, and was only signifi cant after 236 days. As growth rate in all pH treatments followed seasonal patterns correlating to changes in seawater temperature, the data were divided into 3 time periods. A positive relationship between shell growth rate (SGR, mm day-1) and pH was observed for the period 1-59 days (temperature ranging between 26.5 & 18.8 & DEG;C), whereas SGR decreased signifi cantly with pH for the following period (60-236 days, temperature ranging between 20.6 & 8.5 & DEG;C). After 236 days (temperature ranging between 27.5 & 14.1 & DEG;C), there was no signifi cant diff erence in SGR among pH. Similar temperature was experienced between the fi rst and third period and the difference in response could be explained as a consequence of an acute negative response versus a longer exposure indicating possible potential for acclimation. Our results highlight the modulating eff ect of temperature and the importance of long-term experiments to better assess impacts of ocean acidification on marine organisms.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Environmental Sciences (hsv//eng)

Nyckelord

ocean acidification

growth rate

shell length

acclimation

Hexaplex trunculus

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