Assessing cockle shells (Anadara granosa) for reconstruction subdaily environmental parameters: Implication for paleoclimate studies |
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Authors: | M-Reza Mirzaei Aileen Tan Shau Hwai |
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Institution: | Marine Sciences Laboratory, School of Biological Sciences, Universiti Sains Malaysia, 11800 Minden, Penang, Malaysia |
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Abstract: | This study aims to investigate the potential of cockle shells as an environmental recorder, examining the environmental factors controlling the shell growth of the intertidal Anadara granosa from west coast of Malaysia. Subdaily environmental factors were recorded from December 2011 to November 2012. A total of 600 individuals were collected on a monthly basis and the shells sectioned from umbo to ventral margin, polished, etched and photographed under a light microscope to observe microgrowth bands and increments. Comparison of correlation matrix between mean increment width and each environmental factor indicated that shell growth had the highest positive correlation with seawater temperature (+0.72) and weak positive correlation with salinity (+0.53). Multiple regression analysis was used to assess independent associations between shell mean increment width and environmental parameters. Study model showed that 60.8% of the variation in shell growth could be explained by temperature, salinity, rainfall and tidal change. Individually, temperature and salinity made the greatest unique contribution to explain shell growth, respectively (p < 0.01). Laboratory results showed shell growth was in a linear trend to optimum temperature and salinity. These findings provide a basis for the interpretation of the temporal changes in shell microgrowth patterns in terms of environmental conditions of cockle shells. |
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Keywords: | growth pattern shell microgrowth increments intertidal temperature salinity shell cross section |
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