Vol. 12, Issue 4 (2023)

Author(s):
Dr. Chandrakant Lingadhal, Dr. Padmanabha A, Dr. Rajanna KB, Dr. TS Annappaswamy and Dr. Lakshmipathi MT

Abstract:
Hydrographical study is an important pre-requisite in nearshore waters as it is very susceptible to natural and manmade influence. In this paper, attempt has been made to study the spatial and temporal variations in hydrographical properties of the nearshore waters of Keni and Belekeri, Ankola, Uttara Kannada district, Southwest coast of India during the period from October 2020 to September 2021. The air and water temperatures ranged from 25.5 to 33.5 °C and 26.0 to 34.5 °C respectively, pH varied from 8.0 to 8.6, salinity fluctuated from 16 to 34PSU, dissolved oxygen ranged from 4.88 to 8.54 mg/l, ammonia-nitrogen varied from 0.63 to 32.52 µg-at./l, concentrations of nutrients, viz., nitrite-nitrogen and nitrate-nitrogen ranged from 0.06 to 8.13 µg-at./l and 0.13 to 15.67 µg-at./l respectively, phosphate-phosphorus and silicate-silicon varied from 0.29 to 3.53 µg-at./l and 2.44 to 72.71 µg-at./l respectively were recorded. The higher values of temperature, pH and salinity were recorded during pre-monsoon season. In contrast, an increase in dissolved oxygen, ammonia, nitrite, nitrate, phosphate and silicate were observed during monsoon season. Dissolved oxygen, ammonia and silicate showed significant positive correlations with each other, nitrite showed a significant positive correlation with nitrate and salinity showed significant negative correlations with dissolved oxygen, ammonia and silicate. The hydrographical parameters showed significant spatial and temporal variations.The present baseline information is useful for the further ecological monitoring and assessment along the coastal beaches.