In situ photosynthetic performance of Porites lutea inhabiting contrasting habitats of the Northern Straits of Malacca (NSoM), Malaysia

Abstract

ABSTRACT Coral reefs in the Northern Straits of Malacca (NSoM), Malaysia, are frequently exposed to high concentrations of total suspended solids (TSS), thus reducing the light availability for photosynthesis. This study describes the photosynthetic performances of Porites lutea inhabiting contrasting habitats of Pulau Kendi, Pulau Songsong, and Pulau Payar in the NSoM. The light attenuation (Kd (PAR)) was significantly different between all sites, whereby highly turbid water of Pulau Kendi has the highest Kd (PAR) (m−1) = 0.8 ± 0.0 and TSS (mg/L) = 95.7 ± 2.5 in comparison to the protected reef in Pulau Payar, Kd (PAR) (m−1) = 0.5 ± 0.0 and TSS (mg/L) = 36.7 ± 0.4. Here, Pulse-Amplitude-Modulated fluorometry (PAM) and Rapid Light Curves (RLCs) indicate that P. lutea exhibits a different trend of photosynthetic performances to cope with in situ light availability. Turbid waters of Pulau Kendi were observed to provide some protection from light-induced photoinhibition whereby the maximum photosynthetic yield (F v /F m = 0.8 ± 0.0) was significantly higher than those in Pulau Payar and Pulau Songsong. This observation suggested that they could survive near darkness with low light availability for photosynthesis, but a significant reduction in photosynthetic capacity (rETRmax = 77.5 ± 7.4) was also observed. In contrast, greater photosynthetic capacities were observed in P. lutea inhabiting the high-light environment of Pulau Payar. This study emphasized that P. lutea can photoacclimate by maximizing light availability for photosynthesis to ensure survival in turbid nearshore environments.