INTRODUCTION:

The inland freshwater ecosystem has great potential of primary producers which constitutes a significant position in the trophic levels of aquatic ecosystem. The biological productivity of any wetland depends largely on its ability to support the growth of autotrophic organisms consisting algae and macrophytes (Kumari and Kumar, 2002). Primary production studies are important in estimating pollution nature, nutrient enrichment and standing crop of any wetland ecosystem. The solar energy is trapped by green plants is called primary productivity and thus represent whole metabolic cycle in the any natural ecosystem. Many workers have correlated nutrients quantity in estimation of trophic status of wetlands. These nutrients help in chlorophyll synthesis and acting as carriers of essential materials and so it is needful to estimate the major nutrients and their role in the aquatic productivity (Paul and Verma, 1999). A deficiency or excess of these nutrients leads to unbalance the ecosystem. High rate of production both in natural and man-made ecosystems occur when physico-chemical factors are favorable. Biological production is the key to the extent to which natural wetland resources may be utilized for whatever purpose (Bohra and Kumar, 2002).

Ferris and Tyler (1985) documented relationship between chlorophyll and phosphorus. Comita (1985) reported seasonal cycles of primary production. Khan et al (1988) also reported relationship between nutrients and primary productivity. High rate of production both in natural and man-made ecosystems occur when physico-chemical factors are favorable. Biological production is the key to the extent to which natural wetland resources may be utilized for whatever purpose (Bohra and Kumar, 2002). The fish production in wetlands and other water bodies is gaining importance to combat and fulfill animal protein needs. This demand can only be fulfilled by increasing the fish production in several utilized wetlands and other water habitats with diverse geological and climatic features of India. This can be achieved only by increasing the primary production in these wetlands as it forms the basis of increasing production at the next trophic level.

The present study gives an account of primary production in Shatiya wetland sites at Gopalganj district of North Bihar. The study of primary production includes gross primary productivity, net primary productivity and community respiration, where organic matter is accumulated when GPP exceeds CR and therefore NPP can also be used as an index of secondary productivity (Brylinsly, 1980).

METHODS AND MATERIALS:

Studies were made at monthly basis on selected two sites of Shatiya wetland from January 2020 to December 2020. The wetland sites were selected for the analysis purposes. First site is located in the peripheral area and is designated as site 1. Site 1 is located near about Tadwan in the North direction while site 2 is present in the central zone of the wetland and is about 200 m near Alapur. Both the Sites are about 1.5 km apart from each other. Water is present throughout the year at site 2. While during few months of summer site 1 becomes dry. The maximum water at site 2 was recorded up to 4 feet during summer season while during rainy season it was up to 7 feet.

Primary production was estimated by measuring the changes in the dissolved oxygen (DO) concentration in light and dark bottles after following methodology of Gaarder and Gran (1927) and Vollenweider (1969). The dissolved Oxygen (DO) was determined on the site in the field itself using Wrinkler’s modified technique as described in APHA (1992). Chlorophyll was estimated after following methodology given by Trivedy and Goel (1984).

RESULTS AND OBSERVATIONS:

The wetland showed fluctuations in parameters as NPP, GPP, Community respiration and Chlorophyll quantity during the study period was given in Table 1.

Table 1: Monthly variation in Primary productivity, Community respiration and Chlorophyll a in Shatiya wetland sites

Sites→	NPP (gC/m3/hr)		GPP (gC/m3/hr)		CR (gC/m3/hr)		Chl a (mg/l)
Months↓	Site 1	Site 2	Site 1	Site 2	Site 1	Site 2	Site 1	Site 2
Jan	0.689	0.566	0.825	0.728	0.138	0.164	0.833	0.724
Feb	0.925	0.677	1,025	0.785	0.102	0.110	0.564	0.894
Mar	1.375	1.266	1.421	1.377	0.049	0.113	2.612	2.592
Apr	1.575	1.466	1.715	1.644	0.143	0.180	2.922	2.848
May	1.640	1.577	1.825	1.715	0.188	0.140	3.132	2.826
Jun	1.727	1.216	2.138	2.142	0.407	0.928	3.212	3.362
Jul	1.525	1.430	1.815	1.926	0.292	0.498	3.072	3.037
Aug	1.619	1.668	1.818	1.919	0.201	0.253	2.563	3.141
Sep	1.221	1.290	1.503	1.604	0.284	0.316	2.821	2.705
Oct	1.393	1.374	1.583	1.705	0.192	0.331	3.153	0.917
Nov	1.734	1.282	1.833	1.955	0.101	0.675	3.263	2.066
Dec	1.144	1.345	1.233	1.356	0.091	0.013	1.439	2.467

There site 1 showed NPP variation 0.689gC/m³/hr as recorded in January and 1.142gC/m³/hr in December 2020, whereas 0.566gC/m³/hr as recorded in January and 1.345g C/m³/hr recorded in the month of December 2020 with high value in Summer, moderate in monsoon and low in winter season during the study period.

The GPP at site 1 showed GPP variation 0.825gC/m³/hr as recorded in January and 1.233gC/m³/hr in December 2020, whereas 0.728gC/m³/hr as recorded in January and 1.356gC/m³/hr recorded in the month of December 2020 with high value in Summer, moderate in monsoon and low in winter season during the study period.

Similarly community respiration (CR) rates were also found to fluctuate in Shatiya wetland sites (Table 1). The Community respiration (CR) at site 1 showed 0.138gC/m³/hr as recorded in January 2020 and 0.091gC/m³/hr in December 2020, whereas 0.164gC/m³/hr as recorded in January 2020 and 0.013g C/m³/hr recorded in the month of December 2020 with high value in Winter, moderate in monsoon and low in winter season during the study period.

The Chlorophyll a at site 1 varied as 0.833 gC/m³/hr in January 2020 and 1.437gC/m³/hr in December 2020, whereas 0.724gC/m³/hr in January 2020 and 2.467gC/m³/hr in December 2020 with high value in May to July and October and November and low in January and February months during the study period.

Table 2: Statistical summary of parameters and variables in Shatiya wetland sites

Parameters	Variables	Sites	Coefficients of variation (r )	Significance (p=0.005)
Gross Primary productivity (GPP)	Chlorophyll a	Site 1	0.705	+
	Chlorophyll a	Site 2	0.006	+
	Phytoplankton	Site 1	0.571	-
	Phytoplankton	Site 2	0.664	+
	Water Temp	Site 1	0.694	+
	Water Temp	Site 2	0.045	+
Net Primary productivity (NPP)	Phytoplankton	Site 1	0.446	-
	Phytoplankton	Site 2	0.866	-
	Chlorophyll a	Site 1	0.743	+
	Chlorophyll a	Site 2	0.612	+
	Water Temp	Site 1	0.634	+
	Water Temp	Site 2	0.634	+
Chlorophyll a	Phytoplankton	Site 1	0.134	-
Chlorophyll a	Phytoplankton	Site 2	0.333	-

The statistical analysis of parameters showed significant r value in terms of both GPP and NPP except phytoplankton biomass, while variables are significant in terms of water temperature (Table 2).

DISCUSSION:

The primary production involves photosynthetic and chemosynthetic processes which resultantly working for energy flow in the ecosystem. In the present study of primary production in Shatiya wetland sites is more or less similar status in terms of GPP, NPP, CR and Chlorophyll value during the study period. Seasonal variation of primary productivity does not remain same throughout the study is in same pattern with previous researchers in tropical aquatic ecosystems (Prasad and Nair, 1963 and Ali and Khan, 1979). Also, the values recorded of gross production were always found higher than the values of net primary production. It was due to the fact that phytoplankton cells lose an large carbon load during different metabolic activities particularly through respiration and excretion (Haque, 1991). A large population under unfavorable conditions may have a low rate of production, whereas a small population under favorable conditions may have high rate of production (Bohra and Kumar, 2002).

In the present investigations bimodal variations were recorded in the primary productivity showing peaks of higher rates of NPP during summer, and post monsoon seasons at wetland sites. The variation in the rates of production as noted might be due to favorable and unfavorable abiotic factors during different months in this wetland. A higher rate of production indicates that this wetland is primarily rich in nutrients with enough lighted zone and energy content. The maximum rate of NPP during summer periods of investigation was probably due to high temperature and appreciable phytoplankton density. This concept was also reported by Gaur (1998) as high value during summer and at the time of good plankton production. Higher values of primary production during some months of post monsoon and monsoon, in wetland sites were exhibited due to increased nutrients biomass added along with the surrounding agricultural fields. The higher primary production has also reported during summer and monsoon seasons (Ayyappan and Gupta, 1985). The low productivity in winter months might be related with low temperature, less photoperiod and low intensity of light due to dense fog cover and less sunshine or visibility.

The photosynthetic rate of phytoplankton and other green algae has been noticed to be in higher value at some intensity between extremes of mid-day irradiance at the surface (Lewis, 1974). The statistical analysis showed positive correlation of GPP and NPP with Chlorophyll and water temperature (Table 2) at the wetland sites but with phytoplankton, the values showed a non-significant positive correlation at site 1 and negative correlation at site 2 of Shatiya wetland (Table 2).

Community Respiration (CR), the rate of plankton respiration was also estimated in terms of gC/m³/hr. The values of CR were found to vary from season to season and from one to another site of this wetland during the investigation period, which may be exhibited with high rate of organic decomposition in the wetland sites and some turbid conditions during different months of investigations.

There is similar variation of Chlorophyll ‘a’ in the wetland sites (Table 1). Welch (1952) stated Chlorophyll a as a standing crop measure of phytoplankton in aquatic ecosystems. The spatial variations in the values of Chlorophyll ‘a’ showed almost the same trend as exhibited by NPP. The high values of GPP and NPP in the Shatiya wetland sites were correlated with Chlorophyll amount. A correlation analysis also showed significant direct relationship between Chlorophyll ‘a’ and GPP and NPP in this wetland (Table 2).

CONCLUSION:

These wetlands were found to be highly productive showing peaks during summer and post monsoon seasons. Higher rates in productivity as compared to reported ones, indicates that these wetlands are primarily rich in nutrients with enough lighted zones and energy content being productive in nature and free from pollution load, except sewage input. These wetlands of Aligarh region of northern India can very well be used intensively for pisciculture or even for integrated fish farming after following the modern technology used and recommended by CIFA, Kaushalyaganga, Bhubneshwar, Odissa for their proper management.

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Received on 17.02.2022 Modified on 24.02.2022

Research J. Science and Tech. 2022; 14(1):37-40.

DOI: 10.52711/2349-2988.2022.00005