Fig 1.
Map of Chilika Lagoon with sectoral zonation; i) Northern Sector (macrophyte dominated), ii) Central Sector (partially macro algae-SAV dominated), iii) Southern Sector (seagrass dominated), and iv) Outer Channel (tidally active).
ArcGIS ver 10.5.1 was used for creating the map.
Table 1.
Mean (± SD) seasonal variation of physico-chemical parameters, nutrients and sediment organic carbon of surface waters of the Chilika Lagoon; numbers in parentheses indicate the observed range.
Fig 2.
Distribution of pCO2 with respect to salinity in different sectors of Chilika Lagoon; SS = Southern Sector; CS = Central Sector; NS = Northern Sector and OC = Outer Channel.
Table 2.
Mean (± SD) seasonal variation of CO2 and CH4 concentrations and fluxes from surface waters of the Chilika Lagoon; numbers in parentheses indicate the range observed.
Table 3.
Mean (± SD) seasonal variation of CO2 and CH4 concentrations and fluxes from surface waters of rivers entering the Chilika Lagoon; numbers in parentheses indicate the range observed.
Table 4.
Correlation results between pCO2 and salinity of all the sectors of the Chilika Lagoon.
Fig 3.
Distribution of pCO2 with respect to DO saturation at different parts of the Chilika Lagoon; SS = Southern Sector; CS = Central Sector; NS = Northern Sector and OC = Outer Channel.
Fig 4.
Excess DIC distribution during the dry and wet seasons at different sectors of the Chilika Lagoon; SS = Southern Sector; CS = Central Sector; NS = Northern Sector and OC = Outer Channel.
(Error bars represent Standard Deviation).
Fig 5.
Residual methane between observed concentrations and values estimated from conservative mixing with respect to salinity during a) dry and b) wet seasons in different sectors of the Chilika Lagoon; SS = Southern Sector; CS = Central Sector; NS = Northern Sector.
Table 5.
Correlation results between CH4 residuals and salinity (S) of all the sectors of the Chilika Lagoon.
Fig 6.
Influence of sediment organic carbon (SOC) on the distribution of dissolved CH4 in different sectors of the Chilika Lagoon; SS = Southern Sector; CS = Central Sector; NS = Northern Sector and OC = Outer Channel.
Fig 7.
Influence of seagrass cover (%) in Southern sector on CH4 flux (mmol m-2 d-1).
During wet season, seagrass cover never surpasses 60%. Seagrass density is reduced drastically due to its decay (influenced by higher freshwater input) contributing to higher CH4 emission rates in the wet season (Error bars represent Standard Deviation).
Fig 8.
Air- water exchange flux of CO2 and CH4 in terms of CO2 equivalents (CO2e) during present study from different parts of the Chilika Lagoon.
SSD = Southern Sector Dry; SSW = Southern sector Wet; CSD = Central Sector Dry; CSW = Central Sector Wet; NSD = Northern Sector Dry; NSW = Northern Sector Wet; OCD = Outer Channel Dry and OCW = Outer Channel Wet; SS = Southern Sector, CS = Central Sector; NS = Northern Sector; OC = Outer Channel.
Fig 9.
Relationship between CO2 and CH4 fluxes in Seagrass dominated southern sector, Lagoon waters of central sector and Macrophyte dominated northern sector of the Chilika Lagoon.
Table 6.
Correlation results between CO2 and CH4 fluxes of all the sectors of Chilika Lagoon.