Indian Journal of Geo Marine Sciences Vol. 47 (01), January 2018, pp. 193-199 Pre-monsoon and monsoon seasonal changes in physico-chemical characteristics of Chinnamuttom and Colachel harbour waters, Southeast coast of India Nithya, P1., B. Dhanalakshmi1, .P. Santhanam2* & S. Dinesh Kumar2 1PG and Research Department of Zoology, Nirmala College for Women (Autonomous), Coimbatore-641018, Tamil Nadu, India 2Marine Planktonology & Aquaculture Lab., Department of Marine Science, School of Marine Sciences, Bharathidasan University, Tiruchirappalli-620 024, Tamil Nadu, India. * [E-mail: [email protected], [email protected]] Received 02 November 2015 ; revised 17 November 2016 º Seasonal variations in physico-chemical parameters such as atmospheric temperature, surface water temperature ( C), -1 pH, salinity (psu) and dissolved oxygen (mg L ) in Chinnamuttom and Colachel harbours waters were 26-33 (S1), 26-32.3 (S2); 23.6-26.8 (S1), 23.2 -26.4 (S2); 7.44 -8.12 (S1), 7.46 -8.11 (S2); 27.1 -33.5 (S1), 27-33 (S2); 3.8-5.3 (S1), 4.1-5.6(S2) respectively. Ranges of inorganic nutrients (mg L-1) viz., phosphate, nitrite, nitrate, reactive silicate and ammonia were 0.59-1.96 (S1); 0.56-1.93 (S2); 0.79-1.77 (S1), 0.63 -1.74 (S2); 0.097-0.4 (S1), 0.095-0.38 (S2); 0.65-0.77 (S1), 0.64-0.77 (S2); 0.01-0.03(S1), 0.014-0.032(S2) respectively. Physico-chemical parameters of harbour waters have obtained important seasonal and spatial variations. Due to increased harbour activities in both the selected study sites over the last decades, there has been a lot of anthropogenic stress on the aquatic ecosystem. There is an urgent need to evaluate the pollution status of selected harbour waters so as to protect marine life and to minimize the impact of port and shiping activities on surrounding ecosystem. [Keywords: Harbour waters, water quality, temperature, salinity, nutrients] Introduction system are mainly controlled by the fluctuations in the The environmental conditions such as topography, physical and chemical characteristics of the water water movement and stratification, salinity, oxygen, body5. To improve the management of harbors, its temperature and nutrients characterizing particular water quality conditions should be thoroughly water mass also determining the composition of its assessed. The present study is to assess the physical biota1,2. Usually in the near shore waters and characteristics as well as to collect information on the estuaries, they exhibit considerable seasonal chemical conditions of the selected harbor water. variations depending on the local condition of rainfall, tidal incursions, various abiotic and biotic processes, Materials and Methods quantum of fresh water inflow affecting the nutrient Kanyakumari stands to gain with a number of cycle of different coastal environments3. The healthy fishing harbour works in progress. Chinnamuttom lies condition of the any aquatic system depends upon its in between the coordinates of 8°5'45"N; 77°33'47"E. physical, chemical and biological characteristics, The town is located on the Eastern coastal side of which actually fluctuates with season and degree of Kanyakumari district falls in the coordinates of pollution. Physico-chemical characteristics are indeed 8°09′N and 77°08′E / 8.15°N and 77.14°E / 8.15 and vital parameters for monitoring and assessing water 77.14. An eastern and western breakwater approaches quality due to their instability4. The nature and to Colachel fishing harbour. Colachel has always been distribution of the flora and fauna in the aquatic a fishing harbour. The livelihood of most people 194 INDIAN J. MAR. SCI., VOL. 47, NO. 01, JANUARY 2018 around this harbour is fisheries dependent. while the lower air temperature reported during the The sample collection was carried out from the monsoon season and attributed it to the effect of following two stations. Station 1- Chinnamuttom atmospheric cooling8 and upwelling of cooling water fishing harbour situated nearly 2 km away from near the shore9. In both Chinnamuttom and Colachel Kanyakumari town. Station 2 - Colachel harbour is a maximum value was recorded during the month of natural harbour in Kanyakumari district in Tamil July, 2014 which could be attributed to high solar Nadu located 20 km away from Nagarcoil of Tamil radiation in the season. Surface water temperature is a Nadu. According to the standard procedures the water universal factor in the aquatic ecosystem, which may samples were collected in clean polythene bottles influence the physico-chemical characteristics and without any air bubbles. The bottles were rinsed also distribution of the organisms. Surface water before sampling and tightly sealed after collection and temperature in the Chinnamuttom varied from 23.6 to labelled in the field. The samples were kept in ice box 26.8 ºC (Fig. 1b). Minimum and maximum value was maintained at 4°C and were analysed according to recorded during the month of November and August, following standard methods. 2014. At Colachel the value ranged from 23.2 to 26.4º The temperature and salinity of the water in both C. Minimum (23.2º C) was recorded during the month the stations was recorded in the spot using standard of November, 2014 because of strong land sea breeze mercury Thermameter and hand refractometer (Erma, and precipitation and maximum was recorded (26.4º Japan) respectively. Dissolved oxygen was estimated C) during the month of August could be attributed to by modified Winkler’s method6. Inorganic nutrients higher solar radiation10-14. like phosphate, nitrite, nitrate, silicate and ammonia Water pH ranged between 7.44 and 8.12 (Fig. 1c). were estimated by adopting the method described by Minimum (7.44) and maximum (8.12) pH was Strickland and Parsons6. noticed at Chinnamuttom in October 2014 and July, 2014 respectively. pH value determines whether water Results and Discussion is acidic or alkaline. The pH range between 5 and 9 is As environmental damage from human activities not directly lethal to organisms (fishes). However the due to urban industrialization and developments toxicity of several common pollutants is markedly increasingly affects the water quality of surface affected by pH changes within this range and waters, there is an acute societal and global need to increasing acidity or alkalinity may make these monitor water quality characteristics of some waters7. poisons more toxic15. In the present study, pH at So in the present study the two stations Chinnamuttom varied from 7.44 to 8.12. Minimum (Chinnamuttom S-I and Colachel S-II) were chosen was recorded during the month of October, 2014 and and their water quality was analysed. Monsoon and maximum during the month of July, 2014. At pre-monsoon variations in meteorological and Colachel, pH varied from 7.46 to 8.11. Minimum was physico-chemical parameters viz., atmospheric recorded during the month of October, 2014 may be temperature, surface water temperature, pH , salinity, due to dilution effect and maximum during the month dissolved oxygen, inorganic nutrients such as of July, 2014 could be due to higher phytoplankton phosphate, nitrate, nitrite, silicate and ammonia photosynthetic activity16. The main reason of higher content in harbour waters were analysed for a period alkalinity in the harbour water may have been of 6 months from July to December 2014. Physico- influenced by the presence of domestic waste and the chemical parameters of the harbour environment absence of normal tidal action, which would have had observed in the present study showed both spatial and flushing and diluting effect on dissolved constituents temporal variations. Atmosphere temperature varied as well as bi-carbonates which could increase between 26 and 33 ºC (Fig. 1a). The minimum (26 ºC) alkalinity levels. Seasonal influence resulting to was recorded at both the station in November 2014 higher alkalinity values during the rainy season, over while the maximum (33 ºC) was recorded at levels in the dry season was also reported by Chinnamuttom in July 2014. The temperature is one Alabaster and Lloyd17. Salinity fluctuation was of the important factors in the coastal ecosystem, found between 27 and 33.5psu (Fig. 1d). Minimum which may influence the distribution and abundance (27psu) was recorded at Colachel in October 2014 of flora and fauna, in the present study atmospheric while the maximum (33.5psu) was observed at temperature in the Chinnamuttom varied from 26 to Chinnamuttom in July 2014. Salinity varies in 33 ºC while in Colachel it varied from 26 to 32.3º C. different ecosystems according to the topography, Minimum value was recorded during the month of tides (high and low tide) and freshwater inflow. The December, 2014 which could be due to the cloudy sky salinity in the Chinnamuttom was minimum (27.1psu) NITHYA et al.: SEASONAL CHANGES IN PHYSICO-CHEMICAL CHARACTERISTICS OF HARBOUR WATERS 195 during the month of October, 2014 and 1d) Salinity maximum (33.5psu) during the month of July, 2014. 1a) Atmosphere temperature Atmosphere (ºC)Atmosphere Temperature 1e) Dissolved oxygen 1b) Surface water temperature Fig. 1a-d— Monthly variation in physico-chemical characteristics at Chinnamuttom and Colachel harbour waters In Colachel salinity ranged from 27 to 33psu. 1c) pH Minimum was recorded during the month of October, 2014 may be because of freshwater discharge caused by precipitation and the maximum during the month of July, 2014 due to higher solar radiation besides evaporation11. Dissolved oxygen content was varied from 3.8 to 5.6 mg L-1 (Fig. 1e). Minimum (3.8 mg L-1) was recorded at Chinnamuttom in July 2014 while the maximum (5.6mg L-1) was observed at Colachel in November 2014. Dissolved oxygen concentration varies according to many factors; the main factors are photosynthesis and respiration by plants and animals in water. It has been observed from the present study that dissolved oxygen in Chinnamuttom was varied from 3.8 (July, 2014) - 5.3 mg L-1 (November, 2014).