RESCON 2024

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https://ir.lib.pdn.ac.lk/handle/20.500.14444/2080

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Browsing RESCON 2024 by Author "Abhishek, R. S. P. K."

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    Aragonite saturation and nutrient levels on coral reefs in the eastern and southern coasts of Sri Lanka
    (Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2024-11-01) Abhishek, R. S. P. K.; Vithanage, M.; Thilakarathne, E. P. D. N.; Samarasekara, R. S. M.; Bandara, J.; Perera, Nayani; Chandrarathna, Isuri
    Corals rely on adequate aragonite saturation level (Ωar) in the ocean. Reduced Ωar makes corals more susceptible to dissolution. High concentrations of phosphate (PO₄³⁻) lower the Ωar and nitrate (NO₃⁻ ), intensifying coral bleaching during heat stress. Identifying how these parameters affect corals can guide effective interaction strategies to protect these ecosystems. This study evaluated the Ωar, NO₃⁻ , and PO₄³⁻concentrations of coral reefs on the eastern coast (EC) and southern coast (SC) of Sri Lanka from March to May 2024 during the global coral bleaching event. Sampling was done in six sites on EC (Pasikudah, Kalkudah, Pigeon Island, Kayankerni, Adukkupar, and Salli Beach) and six sites on SC (Polhena, Mirissa, Talaramba, Weligama, Unawatuna, and Hikkaduwa). Three water samples were randomly collected from each coral reef from the sea surface, and salinity, pH, and temperature were recorded on-site. A set of samples was preserved at 4 ºC and immediately transported to the laboratory to determine total alkalinity, NO₃⁻ , and PO₄³⁻ concentrations. Total alkalinity and PO₄³⁻data were plotted using R 4.3.1 software for Ωar calculation. The mean values of the Ωar, NO₃⁻ and PO43- on the SC were 4.21 ± 0.43, 2.19 ± 1.28 μmol/L, and 0.74 ± 0.22 μmol/L, and the same on the EC were 4.44 ± 0.29, 1.29 ± 0.91 μmol/L, and 0.35 ± 0.07 μmol/L, respectively. One-way ANOVA test confirmed no significant difference (p > 0.05) of Ωar in sampling areas. However, there was a significant difference (p < 0.05) in NO₃⁻ and PO₄³⁻ concentrations in sampling areas. Results showed Ωar was above the ecological threshold (3.5-3.6). Higher NO₃⁻ concentrations above 2 μmol/L in the SC were likely due to human activities, which may intensify coral bleaching during heat stress. The current result showed that Ωar in both coastal areas was ideal for coral formation and growth.