Climate change is one of the most critical global challenges today where CO2 concentrations in atmosphere are increasing at an alarming rate. Eutrophication is another environmental problem which is driven by the nutrient enrichment caused by anthropogenic activities. The present work was conducted to study the relationship of eutrophication status to ocean acidification in Mumbai coastal waters. Sampling was carried along the Mumbai coast at four different locations based on the stress factors like pollution, sewage discharge etc. Water quality parameters such as water temperature, salinity, pH, dissolved oxygen, alkalinity, ammonia, nitrate, nitrite and phosphate were estimated for all the stations from September 2017 to May 2018 for a time period of 9 months. Water temperature varied from 25 to 31°C, pH: 7.4 to 8.3, salinity: 32 to 39ppt, dissolved oxygen: 2 to 9.6mg/l, alkalinity: 125 to 364mg/l, ammonia: 4.77 to 22.14μM nitrate: 10.22 to 38.18μM, nitrite: 0.21 to 7.67μM, phosphate: 0.09 to 7.25μM. The physicochemical parameters such as temperature, salinity, pH and alkalinity were used as the inputs in the CO2sys program (Lewis and Wallace, 1998) and the pCO2 level (μatm) was estimated for the Mumbai waters. The resultant pCO2 was found to range from 204 to 1770μatm which is significantly higher than the global average value of 380μatm.
The result of the present study clearly indicate the susceptibility of coastal waters towards ocean acidification as a consequence of higher magnitude of eutrophication status prevailing in the near shore areas adjacent to metropolitan cities like Mumbai. Thus the marine species inhabiting in this variable coastal environments is more pronounced to ocean acidification effects.