SEASONAL VARIATIONS IN WATER AND SEDIMENT DYNAMICS IN THE MANGROVE WETLANDS OF KANDALERU CREEK, NELLORE DISTRICT, ANDHRA PRADESH, SOUTH COAST

Transcription

1 J. Indian bot. Soc. ISSN Vol. 94 (3 & 4) 2015 : SEASONAL VARIATIONS IN WATER AND SEDIMENT DYNAMICS IN THE MANGROVE WETLANDS OF KANDALERU CREEK, NELLORE DISTRICT, ANDHRA PRADESH, SOUTH COAST Department of Botany, Jawahar Bharati Degree & P.G.College, Kavali rao.nsrk@gmail.com Seasonal variations in physico-chemical characteristics of water and sediment in the Kandaleru mangrove ecosystem in Nellore district was carried out during Statistical analysis of the data showed that except surface water temperature, Zn and Cu, all other variables were affected by seasons. Except ph and salinity the other variables were not affected among the three habitats. Correlation of coefficient between several pairs of variables showed high degree of correlation. Key words : Physico-chemical characteristics, Kandaleru, Mangroves, ANOVA, Coefficient of correlation Mangroves are a unique, dynamic, evergreen and multifunctional ecosystem occurring along the land-sea interface. They are also described as marine tidal forests or coastal wet lands; found at intertidal zones of tropical and subtropical belts, inhabiting tidal creeks, estuaries, river banks, deltas and broad mud flats. These complex ecosystems occur between latitudes 38 north and 38 south along the tropical coasts of Australia, Asia and the Americas. The greatest mangrove diversity exists in southeast Asia. Mangrove wetlands are subject to daily exchange between brackish and fresh water and frequent tidal inundation. The mangals are a specialized ecological group adapted to high salinity, anaerobic soils and environmental stress through special morphological, anatomical and physiological features. Among other functions, mangroves act as a bio-shield against tidal waves, promote soil conservation, sustainable fisheries, provide medicinal products and fodder and firewood and sequester carbon (Kathiresan and Qasim 2005, Swain and Rama Rao 2008). There are several reports on the effect of physico-chemical factors on the mangroves of the south-east coast of Tamil Nadu (Ashok Prabhu et al. 2008, Govindasami et al. 2000, Manikannan et al. 2011, Srilatha et al. 2013, Vijayakumar et al. 2000, Saravanakumar et al. 2008). Krishna Rao (2013) studied the effect of some seasonal changes on the physicochemical parameters on the mangrove habitat of Iskapalli lagoon in Nellore district. Except for this, no comprehensive studies have been conducted with reference to the seasonal variations on physico-chemical factors on the mangrove habitats of Prakasam and Nellore districts comprising south coast of Andhra Pradesh. The objective of the present study is analyze the season-wise effect of water and nutrient dynamics on three major mangrove habitats of Kandaleru creek of Nellore district in the south coast. MATERIALS AND METHODS Study area Nellore district is located at 13 30'-15 10' N longitude and 79 5'-80 16' E latitude. The district has a coastline of 175 km. along Bay of Bengal. In Nellore district there are no major rivers except the Pennar. Swarnamukhi and Kandaleru are non-perennial rivers traversing the district before joining the Bay of Bengal. Kandaleru creek, a 45 km. long creek which is essentially a drainage canal of the watershed of the region and maintains a permanent opening with the Bay of Bengal. Kandaleru creek lies between '24" 14 15'40" N and 80 00' 15" 80 08' 10" E. The creek begins its course near Gudur town in Nellore district, traverses through villages / hamlets in four mandals namely Manubolu, Venkatachalam, Chillakur and Muthukuru and merges with the sea at Krishnapatnam in Muthukur mandal. The total length of the creek is 45 km of which 11 km is * A talk delivered in the session of 37th All India Conference of The Indian Botanical Society (7-9 Nov.2014) for the award of 'Prof.V.Puri Medal-2014'. Received on May 30, Accepted on August 14, 2015

2 fresh water regime and 34 km is brackish water canal. The width of creek varies from 200 to 250 m and the depth from 1m to 12m. The salinity profile is from fresh water condition during November December to about 25 ppt in May- June and ppt during the rest of the year. The tidal amplitude is about 1.0 m Kandaleru creek supports robust and dense mangroves over a length of about 10 km behind Krishnapatnam where it merges with the Bay of Bengal. Luxuriant growth of mangroves is made possible due to flushing of fresh water and daily tidal water fluctuation, nutrients brought downstream of the creek and from the sea. The present study was undertaken during 2013 at three mangrove habitats of Kandaleru creek, namely, Varagali (Station 1), Epuru- Venkannapalem (E.V.Palem) (Station 2) and Gummaalladibba (Station 3).The first two stations are at least 1 km apart and 5 km away from the sea while Station 3 is very close to Bay of Bengal and is in the neighbourhood of Krishnapatnam. GVR PALEM EPURU BIT-11 EV PALEM EPURU BIT-1-B VARAGALI KRISHNAPATNAM PORT GUMMALLADIBBA Figure 1.The Kandaleru creek showing the sampling stations. Water and mud sediment samples were assessed during summer (April- June), southwest monsoon (July-Sept), north-east monsoon (Oct-Dec) and post-monsoon (Jan- Mar) during the year Surface water temperature, Salinity and D.O were measured for water samples. Except for air temperature and surface water temperature, salinity and D.O. the remaining parameters were determined for mud sediment samples collected close to the mangrove trees. Mud sediment samples were collected with the help of soil corer from a depth of 15 cm every season. Sampling was consistently done at exactly the same spots during the four seasons. Sediment samples were collected in sterile plastic bags, labeled, brought to laboratory, shade-dried to remove moisture and again duly labeled. The fully dried samples were ground and passed through a 2 mm steel sieve and labeled. The ph and electrical conductivity were measured with Elico Digital ph meter and Digital Conductivity meter, respectively. Water salinity was measured with the help of Atachi (Japan) hand refractometer and water D.O. by Elico Dissolved Oxygen meter. The protocol followed in respect of the other parameters is as follows: O.C : Walkley and Black (1934), D.O: Parsons et al. (1989), Available Nitrogen : Subbaiah and Asija (1956), Phosphorus : Olsen et al. (1954), Potassium (Toth and Prince (1949), Magnesium and Calcium: Cheng and Bray (1951), Sulphur: Pandey and Girish (2007) and the micronutrients, Cu, Fe, Mn, and Zn as per Lindsay and Norvell (1978). RESULTS AND DISCUSSION The effect of seasonal variations on physicochemical parameters on the three stations of Kandaleru creek is shown in Tables 1, 2 and 3. Air temperature and Surface Water temperature : At all three stations the maximum air temperature was almost uniform over the four seasons while the minimum temperature was slightly higher at Station 3 (32.6 C) during south-west and post-monsoon seasons. Surface Water temperature was almost uniform for all three stations over all four seasons. Temperature regulates the rate of photosynthesis in aquatic ecosystems. Higher values of air temperature during summer and lower values during monsoon observed during this study confirm the general established trends along the southeast coast and is in conformity with earlier studies (Rajendran and Kathiresan 1999; Manikannan et al. 2011). Surface water temperature largely depends upon solar radiation, evaporation, fresh water

3 Seasonal variations in Water and Sediment Dynamics in the Mangrove Wetlands of Kandaleru Creek 204

4 influx, cooling and mixing due to water currents and tidal flow. ph : The ph of the sediment at all three stations was almost uniform throughout the four seasons. Except during summer, the ph remained alkaline-neutral at all three stations. Alkaline ph is a characteristic feature of marine environment and this is due to presence of sufficient quantities of carbonate (Trivedi and Goel 1984). The increase in ph during monsoon could be attributed to the uptake of CO 2 by phytoplankton for their photosynthetic activity. High ph values observed during monsoon may be attributed to fresh water influx, dilution of sea water, low temperature and organic matter decomposition. The ph trends observed in the present study are in agreement with similar earlier investigations from southeast coast of Tamil Nadu (Palanichamy and Rajendran 2000, Ashok Prabhu et al. 2008, Sundaramanickam et al. 2008, Damotharan et al. 2010, Manikannan et al. 2011). Salinity : Results show that salinity values are higher during south-west monsoon at all three stations as the study area receives rain water only during north- east monsoon. Salinity varies in different ecosystems according to topography, tides and fresh water inflow (Satheeshkumar and Khan 2009). Dissolved Oxygen ( D.O.) : In the present study the D.O. values of water at the sampling stations are higher during summer and postmonsoon. As the water exchange is less and also due to phytoplankton activity the dissolved oxygen is higher during the above period. This is reported in other back water systems in Pondicherry and Kundapura mangrove ecosystem in Karnataka (Satheeshkumar and Khan 2009, Vijakumar and Vijayakumaran 2013). Electrical Conductivity (E.C) : In the present study EC of the sediment was consistently higher during summer than the other three seasons at all three stations. Generally, EC is expected to be lower during monsoon due to rain water mix up, decline in rate of evaporation and temperature. Results obtained here are in agreement with earlier studies (Manikannan et al. 2011) during summer and post-monsoon. Organic Carbon (O.C) : O.C. values of the sediment are maximum during south-west monsoon at all three sampling stations which may be due to faster decomposition of leaf and other litter during the period. Islam et al., (2004) and Saravanakumar et al. (2008) also reported higher values of O.C. during monsoon. Available Nitrogen, Phosphorus and Potassium: At all three stations these parameters of the sediment were highest during south-west /north-east monsoon and minimum during summer/ post-monsoon. Of these three parameters, available nitrogen content was highest ( ) followed by Potassium ( ) and Phosphorus ( ). Calcium, Magnesium and Sulphur : The behavioural pattern of these three nutrients in the sediment is similar to that of Available Nitrogen, Phosphorus and Potassium, being highest in content during south-west monsoon and lowest during summer. Their content is much higher than available N, P and K with Ca ranging between , Mg ( ) and S ( ). At all three stations these three nutrients were lowest during summer. These results show that among the major macro-nutrients, at all three stations the content of S was highest during south-west monsoon almost invariably followed by Mg, Ca, N.,K and P in that descending order. The micro-nutrients : At all three stations, in the sediment, Zn content was maximum during the monsoon and minimum during summer while Fe content was maximum during postmonsoon and minimum during summer at all three stations. Copper content was maximum at all three stations during m monsoon while Mn content was maximum during monsoon and minimum during summer. Put together, Zn, Cu and Mn content was high at all stations during monsoon while Fe differed from this trend, recording higher values during post-monsoon. For all three stations, among these micronutrients Fe content was highest, followed by

5 Seasonal variations in Water and Sediment Dynamics in the Mangrove Wetlands of Kandaleru Creek 206 Mn, Zn and Cu in that decreasing order. From the foregoing results it is seen that among the chemical parameters, O.C, N, P, K, Ca, Mg, S and Cu levels were maximum during southwest monsoon while Zn and Mn levels were maximum during north-west monsoon at all three stations. While all the ten parameters stated above registered maximum levels during monsoon, only Fe behaved differently; its levels were maximum at all three stations during post-monsoon. In their study, Srilatha et al. (2013) reported higher levels of total phosphorus, total nitrogen, ammonia and nitrite during monsoon at Muthupettai mangrove region. As with the present study higher levels of phosphorus and nitrogen were reported (Manikannan et al and Sukumaran et al. 2013). In a study on seasonal changes in nutrient constituents of Sundarban mangroves, Enamul Hoq et al. (2002) found that levels of N, P, K, Cu and Zn during monsoon were higher while Ca, Mg and Na were higher during pre-monsoon. Islam et al. (2004) reported higher levels of organic matter, calcium, total nitrogen, phosphorus, copper and iron during monsoon, but levels of Mg, K, S and Zn and Mn were higher during summer in mangrove soils of Sundarbans. Statistical tools/ procedures are used in the analysis of observations and to check the reliability of the data. ANOVA (Analysis of Variance) is one such tool and has been employed here in order to determine whether the different seasons and stations affect the mean levels of the variables under the study in a statistically significant /not significant manner. The table of significant values (Table 4) is included in order to provide a ready reference to the conclusions. From the above table it may be deduced that except for the variables, air temperature, surface water temperature, Zn and Cu, the mean levels of all the other thirteen variables are affected by seasons in a statistically significant manner. Similarly, except for ph and salinity the mean levels of the rest of the other fifteen variables do not appear to be affected by habitats in a statistically significant manner. In

6 other words, except air temperature, surface water temperature, Zn and Cu, the other variables are subjected to temporal effect. Fifteen other variables save ph and salinity are free from spatial effect. Coefficient of correlation among the variables is shown in Table 5. Coefficient of correlation is denoted by' r.' From the Table 5, we may infer that there is 1) a very high positive correlation ( r >0.9 < 1.0) between the following 5 pairs of variables : P-S; Ca-Mg; Mg-S; Mg-Cu; S-Cu; and 2). sufficiently high correlation (r >0.75 < 0.9) between the 13 pairs of variables : E.C-O.C ; O.C-K; N-Mg ; P-K ; P-Ca; P-Mg ; P-Cu; K- Ca ; K-Mg ; K-S; K-Cu; Ca-S; Ca-Cu ). The parameters under the present study are affected by seasons but not by stations. The monsoons, especially south-west, had profound effect by making the nutrients available for rapid growth of mangrove flora. In contrast, during summer, most of the physico-chemical characteristics were at the lowest at all three stations. The author is grateful to UGC, New Delhi for financial support in the form of a major research project, to the authorities of Jawahar Bharati Degree & P.G. College, Kavali for facilities, to Dr. R.Ramasubramanian, Mangrove Biologist, M S Swaminathan Research Foundation, Kakinada for useful suggestions, Dr. K. Hari Narayana and Dr. T.V. Ramana for help in statistical analysis. REFERENCES Ashok Prabhu V, Rajkumar M and Perumal P 2008 Seasonal variations in physico-chemical characteristics of Pichavaram mangroves, Southeast coast of India. J Environ Biol

7 Seasonal variations in Water and Sediment Dynamics in the Mangrove Wetlands of Kandaleru Creek 208 Cheng K L and Bray R H 1951 Determination of Calcium and Magnesium in soil and plant material. Soil Sci Damotharan P, Perumal N V and Perumal P 2010 Seasonal variations in physico-chemical characteristics of Point Calimere coastal waters (southeast coast of India) Middle-East. J Sci Res Enamul Hoq M, Islam M L, Paul H K and Ahmed U 2002 Decomposition and seasonal changes in nutrient constituents in mangrove litter of Sundarbans mangrove. Bangladesh Indian J Mar. Sci Govindasami C, Kannan L and Jayapaul A 2000 Seasonal variations in physico-chemical properties and primary production in the coastal water biotopes of Coramandel coast. Indian J Environ Biol Islam M L, Alam M J, Rheman S, Ahmed S U and Mazid M A 2004 Water Quality, nutrient dynamics and sediment profile in shrimp farms of Sundarban Mangrove forest. Bangladesh. Indian J Mar Sci Kathiresan K and Qasim S Z 2005 Biodiversity of Mangrove Ecosystem. Hindustan Publishing Corporation (India), New Delhi. pp 251. Krishna Rao N S R 2013 Study on the mangrove habitats of Iskapalli lagoon, Nellore district, Andhra Pradesh. J Indian bot Soc Lindsay W L and Norvell W A 1978 Development of a DPTA Soil Test for Zinc, Iron, Manganese and Copper. Journal of Soil Society of America Manikannan R, Subramanian A and Abdul Hameed M S A 2011 Seasonal variations in physico-chemical properties of Vedaranyam Swamp, Point Calimere Wildlife Sanctuary, South-east coast of India. Afr J Environ Sci Tech Olsen S R, Cole C V, Watanabe F S and L A Dean 1954 Estimation of Available Phosphorus in soils by Extraction with Sodium bicarbonate. U.S. Department of Agriculture circular No Palanichamy S and Rajendran A 2000 Heavy metal concentration in seawater and sediments of Gulf of Mannar and Pak Bay, southeast coast of India. Indian J Mar Sci Pandey R N and B H Girish 2007 An improved turbidimetric method for estimation of Sulphur in soil extracts. J Ind Soc of Soil Sci Parsons T M, Malta Y and Lall C M 1989 A manual of chemical and biological methods for sea water analysis. Oxford : Permagon Press. pp 173. Rajendran N and Kathiresan K 1999 Seasonal occurrence of juvenile prawn and environmental factors in Rhizophora mangal, south east coast of India. Hydrobiologia Satheeshkumar P and Khan B A 2009 Seasonal variations in physico- chemical parameters and water sediment characteristics of Pondicherry mangroves. Africans Journal of Basic & Applied Sciences 1 (1-2) Saravanakumar A, Rajkumar M, SeshSerebiah and Thivakaran G A 2008 Seasonal variations in physico- chemical characteristics of water, sediment and soil texture in arid zone mangroves of Kachchh- Gijarat. J Environ Biol Srilatha G, Varadarajan D, Chamundeswari K, and Mayavu P 2013 Study on physicochemical parameters in different mangrove regions, Southeast Coast of India. J Environ Anal Toxicol Subbaiah B V and Asija G L 1956 A rapid procedure for determination of available nitrogen in soil. Curr Sci Sukumaran M, Muthukumaravel K and Sivakami R 2013 Seasonal variations in physico- chemical characteristics of Aginar estuary, south coast of India. Asia Pacific Journal of Research

8 Sundaramanickam A, Sivakumar T, Kumaran R, Ammaiappan V and Velappan R 2008 A comparative study of physico-chemical investigation along Paragipettai and Cuddalore coast. J Environ Sci Technol Swain P K and Rama Rao N 2008 Floristic studies on mangroves of Prakasam district in Andhra Pradesh. In : Bioresources Conservation and Management. Today & Tomorrow's Printers and Publishers, New Delhi. pp Toth S J and Prince A L 1949 Estimation of cation exchange capacity and exchangeable Ca, K and Na by flame photometry technique. Soil Sci Trivedi R K and Goel P K 1984 Chemical and Biological Methods for water pollution studies. Environmental Publication Karad, India. Vijayakumar S K, Rajesh K M, Mridula R M and Hariharan V 2000 Seasonal distribution and behavior of nutrients with reference to rhythm in Mulki estuary, southeast coast of India. J Mar Biol Ass India Vijayakumar K M and Vijayakumaran 2013 Physico-chemical analysis of water quality of Kundapura mangrove forest, Karnataka, India. Global Journal of Biology, Agriculture & Health Sciences 2 (3) Walkley A and Black T A 1934 Estimation of soil organic carbon by chromic acid titration method. Soil Science