Assessment of the relationship between environmental variables and benthic fauna along Padubidri region, Karnataka

Abstract

Monthly assessment of benthic fauna in response to environmental variables investigated along Padubidri, Karnataka, from January 2023 to December 2024. Stratified random sampling method was applied for sampling. A total of 25 benthic species were identified and grouped under four different classes: bivalve (10), gastropod (11), scaphopod (1), and echinoderm (3). The environmental variables such as air temperature (28.36 to 31.21 oC), water temperature (29.79 to 33.24 oC), transparency (1.65 to 5.30 m), pH (7.39 to 8.04), dissolved oxygen (4.43 to 6.71 mg/l), salinity (28.97 to 38 psu), TDS (31874.29 to 60525.71 mg/l), TSS (131.14 to 577.14 mg/l), biologic oxygen demand (1.37 to 2.78 mg/l) were recorded in optimum level. Variations in nutrient concentration such as NH3-N (1.84 to 13.73 µg-at.NH3-N/l), NO2-N (0.57 to 2.72 µg-at.NO2-N/l), NO3-N (0.73 to 3.81 µg-at.NO3-N/l), PO4-P (0.87 to 2.57 µg-at.PO4-P/l) and SiO2-S (36.74 to 59.32 µg-at.SiO2-S/l) were noted. The scaphopod, Dentalium sp., and polychaete showed dominance throughout the study period. The diversity indices express that the benthic diversity was moderate along the coast. The variation in an abundance of benthic fauna could be attributed to changes in environmental variables.