Effect of Physico-Chemical Parameters and Inorganic Nutrient Ions in Relation with Seasonal Algal Diversity of River Ichhamati, West Bengal, India.

The present study reflects seasonal algal diversity as a source of food for fishes in the river Ichhamati during October 2021 to August 2022. To understand the seasonal algal pattern in the river Ichhamati, physico -chemical parameters of river water such as Hardness, Conductivity, pH, Total Dissolve Solids, Turbidity, Dissolve Oxygen, Salinity, Turbidity, Total Alkalinity, Salinity, Biological Oxygen Demand as well as biologically significant inorganic ion concentrations in river water namely sodium, potassium, calcium, carbonate, bicarbonate, nitrate, chloride were also evaluated during study period. It is found that physico-chemical parameters and inorganic ions in river water play an important and significant role in seasonal algal growth. Throughout the study period it was established that river Ichhamati is not very rich in floral diversity. During study time it was observed that dominant group of algae in this river are Chlophytes, Cyanophytes and Bacilariophyceae, including Species of Oscillatoria Nostoc , Klebsormidium , Spirogyra, Lyngbya , Chlorococcum, Chlorella , Diatoms in all seasons. During spring, summer and monsoon Conductivity, salinity, TDS and hardness of river water is high. Ichhamati contained adequate Na+, K+ and NO 3 - in summer and monsoon season. High rate of bio-mineralisation during winter was found due to presence of high calcium ion concentration and also high TDS along with high salinity as well as high hardness of river water.


Introduction
River always plays a vital role sustaining life of any civilisation as it is a prime sector of economy.River is an important source to maintain ecosystem. 1Ichhamati River make its way through India and Bangladesh and also acts as a border between India and Bangladesh. 2 Ichhamati travels a distance of nearly 216 km and finally meet with Kalindi river at Hasnabad, North Moore Island of West Bengal. 3Ichhamati is a branch of Mathabhanga river bifurcates into two branches Ichhamati and Churni at Majdia of Nadia district in West Bengal.Range of algal diversity is wide from lentic to lotic ecosystem. 4Seasonal variation in algal growth in aquatic environment is acquired due to change in nutritional, temperatur, light, grazing pressure level throughout a year. 5Aquatic fauna such as fishes, snails, crabs and others finds a main source of their food from phytoplanktons such as algae.Phytoplanktons present at the base level in aquatic ecosystem forms major source of carbon. 6Depending on water quality algae forms main connection between food chain and its productivity. 7To asses water quality and its to understand its basic nature study of algal diversity play a major role. 8 -,11][19] Sodium, potassium and calcium ions are the bulk metal ions of living system.Presence of high calcium ion concentration leads to high rate of biomineralisation. This study is undertaken to evaluate seasonal algal composition of river Ichhamati water in different seasons such as autumn, winter, spring, summer and Rainy season in relation to some physicochemical parameters and biologically significant inorganic ions.The present study also evaluate presence of available algae act as a source of food for fishes in this river.

Water Sampling and Analysis
River water taken in the month of October -December 2021, January, February, March, May, July and August of 2022 frequently from Ichhamati.Water collected from river were analyzed through Titrimetry method, Flame photometry and spectrophotometric and other methods.On site analysis of pH, Conductivity, Temperature, Total Dissolve Solid, DO, Salinity were made by using proper scientific instruments.After collecting river water preserved in sterile Polyethylene sampling bottles and Turbidity, Total Alkalinity, Na + and K + , Ca + and NO 3 -ions analyzed by using proper scientific instruments and Titrimetric method.All instrumental and titrimetric methods were done at Laboratory.

Algal Sampling
Benthic algae grown on the hard surface of rock collected by using of spatula, scalpel, small knife by scraping algae from hard surface and kept in small jar of polyethylene.With the help of pipette algal specimen collected from soft muddy surface and kept in polyethylene bottle.Some floating algal specimen were collected from water surface by using fine meshed dip nets and with the help of hand and kept for preservation polyethylene sterile bottle.Plankton nets with 50µm mesh size are used for collection of phytoplankton from water.After collecting, specimens were preserved with 3% Formaldehyde solution.Standard microscopic methods were applied for observation of algal specimen.[25][26] Result Water from 7 study locations of Ichhamati River were taken in every season i.e., during autumn, winter, spring, summer and monsoon.Physico-chemical parameters and biologically significant nutrient ions are measured.3 replicas of each parameter have taken.Replicas were taken from same place but from three different spots keeping distance at least 300 meters.IBM SPSS 20 Software and PAST Softare used in this study for statistical analysis and presented in tables below

Discussion
The mean temperature of river water of Ichhamati ranges between 23.2⁰C to 31⁰C throughout study period.It is reported that 25-30⁰C temperature range is ideal for algal growth. 29The present study also suggests these findings.pH value of River Ichhamati ranged between 7.65 to 8.05 and make this slightly alkaline.It was reported that pH range 5.0 to 6.6  increased algal abundance. 30The present study report that slightly alkaline river water is suitable for some algal growth (Table 3).The mean value of Conductivity ranged between 808.5-16026.67µS/ cm.For periphyton algae increased Conductivity can stimulate attached algal biomass and productivity. 31his study also found abundance growth of periphytonic algae during study time.Mean salinity value of river water was 393 to 14096.66 ppm during study time.
Ichhanmati water TDS value found between 577.5 -18457.33ppm.TDS effectively related with salinity to create toxicity and change in ionic composition of fresh water creating limited biodiversity, shifting of aquatic populations and exclusion of weakly tolerable species. 32The present study also found presence of less aquatic flora during high salinity and TDS level but some micro algae may be tolerant of high salinity and TDS as shown in table

Fig 1 :
Fig 1: CCA score at L 1 between river algae and physico-chemical parameters

Fig 2 :
Fig 2: CCA score at L 2 between river algae and physico-chemical parameters

Fig 3 :
Fig 3: CCA score at L 3 between river algae and physico-chemical parameters

Fig 7 :
Fig 7: CCA score at L 7 between river algae and physico-chemical parameters
41Calcium ion concentrations range between 46.50 to 432.50 ppm.Nitrate ion concentration is important factor for promoting algal growth36.Mean nitrate concentration ranged between 344 to 3702ppm.The present study observed high nitrate concentration during March, May and August month of 2022 and probable reason may be addition of chemical manure with rain water used by farmers for agricultural purpose besides river bank.Bicrbonate ion concentration is key for algal photosynthesis.37Bicarbonate ioriver ranged between 155.31 and 205.75 ppm making this good photosynthetic condition throughout the year.This study finds the river water is suitable for growth of Chlorophyceae and Diatoms.. Monsoon has rich variety of vegetation.This study had identified 7 cyanophycian algae, 14 chlorophycian algae and 9 diatoms (Table3) belonging to the family Cyanophyceae, Chlorophyceae, Charophyceae and Bacillariophyceae.Monsoon season present some abundant growth of algal species such as Klebsormidium, Spirogyra, Lymgbya, Nitzschia, Pinnularia.Temperature change during winter may be probable reason for diatoms as dominant species.Fishes preferred diatoms as food.It is reported that dominancy of diatoms in aquatic body improve the growth of fish and shrimp to meet their nutritional demandL.3 8 Ichhamati a number of variety of fishes.We examined gut sample of Mystes tengara and found Spirogyra, Ulothrix, Pinnularia, Chlorella, Pithophora and Chlorococcum from gut sample.So it is clear that algae provide a large part of food for fishes in river Ichhamati.Present study identified 7 cyanophycean algae reportedly having biological nitrogen fixing ability39and resulting river bank soil fertility and cessation of submerged weeds growth.Green algae Chlorella vulgaris conain good quantity of protein40and important source of fish food and their growth, immunity.41ConclusionsItmay be concluded that ecosystem of river Ichhamati is suitable for algal growth and diversity.Data of present observation in the sense of dominance showed by different group of algae and present observation reported accordingly 47% belongs to Chlorophyta, 23% are Cyanophyta and 30% are Diatoms form food reserve for aquatic animal.According to their dominancy various algal division were Chlorophyta > Cyanophyta > Bacillariophyta in the autumn, spring and monsoon.In winter it was observed that the dominancy is Bacillariophyta > Chlorophyta > Cyanophyta and in summer Cyanophycea > Chlorophyceae > Bacillariophyceae.It may also reported that Ichhamati is good for fishery mainly for Hilsha fish.But in spring, summer and rainy season salinity, TDS is very high and this may be mixing of sea water during high tide.Presence of sufficient concentration of nitrate and potassium ions justified that river bank is fertile for agricultural purpose.