Carbon dynamics in the intertidal rockpools along the central west coast of India
Date
2025Author
Nandakumar, K.
Shetye, S. S.
Lakshmi, S.
Kurian, S.
Sarath, R.
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Shallow inter-tidal ecosystems such as rockpools provide important insights into the ongoing climatic changes and their consequences. We studied the diurnal and seasonal variations in carbon chemistry and associated physicochemical parameters of intertidal rockpools along the central west coast of India for four years. The temperature (26��C�39��C), salinity (3�55), pHT (7.79�9.27) and other carbon parameters exhibited a huge variation in the studied rockpools. These significant variabilities were observed in the parameters among seasons and low to high intertidal transition (tidal zone). Ecosystem productivity along with calcification, evaporation, and salinity stress-induced TOC exudation play a key role in the variability of carbon parameters in intertidal rockpools. Productivity resulted in the decrease of alkalinity, bicarbonates (HCO3?), and pCO2 coupled with the increase in pHT, total organic carbon (TOC), and Chlorophyll-a (Chl-a) among the studied pools. Consequently, the dissolved oxygen (DO) concentrations in the system increase to hyperoxia with the highest concentration of 20.27�mL/L during the day, while, the process is reversed at night due to ecosystem respiration. Higher ecosystem productivity in the day counters the carbonate dissolution by respiration at night as indicated by carbonate mineral saturation constants above 1. However, the rockpools are more vulnerable to changes in carbonate chemistry during the southwest monsoon (SWM) due to freshwater influence, along with reduced productivity due to cloud cover. This poses a concern for the calcareous organisms inhabiting these rockpools, as they endure a prolonged duration of carbonate undersaturation state during the SWM. This study suggests that the organisms in the rockpools are already undergoing large variabilities in the environmental stressors that will make them more resilient towards future climatic changes. However, the sudden drastic changes due to marine heat waves, heavy rainfalls, etc can impact these organisms, so monitoring is crucial in the climate change scenario.
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