72

DISCUSSION

Lots of studies on the effects of pollution causing agents have been

carried out through assessment of water quality and planktonic studies in

freshwater systems in India and abroad, however, comparatively little work

on the benthic fauna has been done. Benthos is the integral and inseparable

associates of the biotic components of an aquatic system. They inhabit both

lotic and lentic water systems and forms a major component of the food

chain (Sinha & Das, 1993).

Several species of benthos are highly sensitive to aquatic pollution and

quickly respond even to short term environmental change whereas, the

population of most of the species suffer badly, some of them proliferate

under the changed conditions finding it more suitable for their development

(Sunder, 1996). Reduction in the species diversity, population of several

species and even emergence of new species has been noticed. Any variation

in these parameters have been observed to cause considerable changes in

their population and bio-diversity and thus the study relating to their

population has been considered as an important tool for the determination of

trophic state of a water body.

pH: All biochemical reactions are sensitive to the variation of pH.

Extremes of pH or rapid pH changes can exert stress conditions or kill

aquatic life. Even moderate changes from acceptable criteria limits of pH are

deleterious to some species (Jamil, 2002). There was not much difference in

the pH values between the stations and seasons. The pH of water at all the

stations was found towards alkaline in nature and it supported the growth of

benthic communities. Thus, there was no specific effect of pH in the

succession of benthic communities. Same results were observed by Lund

(1965) and Sahai et al., (1985). Highest pH 8.42 at site-1 in Oct’09, the

Epifloral communities were contributed by Cyclotella sp, Gomphonema sp,

73

Gyrosigma sp, Pediastrum boryanum, Pediastrum simplex, Navicula

radiosa, Navicula cuspidata, Ulothrix sp, Melosira sp. Among faunal

communities Nothalca sp, Monostyla clasteroceraca, Monostyla lunaris,

Monia sp, Daphnia sp, Cladocera, Nematode, tintinnopsis sp, Ostracoda

were found. Lowest pH was found to be 7.03 in site-2, site-3 during May’09

& Dec’09. The Epifloral communities were contributed by Cyclotella comta,

Cyclotella glomerata, Navicula lanceolata, Oscillatoria sp, Cymbella sp,

Gomphonema sp, Gyrosigma sp, Pediastrum sp. Among faunal communities

Copepod, Cladocera, Ostracoda, foraminifera, Boleophthalamus dussumieri

and Nereis diversicola were found.

There was no wide fluctuation in Soil pH except July’08 at site-3. It

was 6.8. This might be due to the drastically changes occur with time due to

exposure with air, biological activity, and temperature changes. The same

observation was cited by (Broominathan and Khan, 1994). Epifloral

communities at highest pH 9.68 at site-3 in May’09 were contributed by

Cyclotella comta, Navicula ambigua, Navicula cuspidata, Navicula

palpebralis, Cymbella sp, Gomphonema sp, Gyrosigma attenuatum,

Gyrosigma proceum, Tabellaria sp. Among faunal communities Copepod,

Nematode, Cladocera, Boleophthalamus dussumieri and Nereis diversicola

were found. Epifloral communities at lowest pH 6.8 at site-3 July’09 were

represented by Coscinodiscus sp, Navicula sp, Amphora sp, Melosira

undulata, Synedra iconic, Synedra mazamaensis, Pinnularia sp,

Scenedesmus obliquus and Scenedesmus quadricauda. Among faunal

communities Nematode, Ceriodaphnia silvestrii, Ceriodaphnia dubia,

Difflugia sp and Boleophthalamus dussumeiri were found.

Water temperature is basically important for its effects on the

chemistry and biological reactions in the organisms present in water. At

higher temperature metabolic activity of organisms increases, requiring more

oxygen but at the same time solubility of oxygen decreases, thus

74

accentuating the stress on aquatic life. The overall sequence of rise and fall

of water temperature was almost the same with minor differences. During

rainy season the water temperature showed decline which may be attributed

to lesser period of insolation, frequent clouds and high percentage of

humidity, high velocity, increased turbidity and high water levels. In

summer, low water levels, clear atmosphere, and high insolation, frequent

clouds, high percentage of humidity, high velocity, increased turbidity and

high water levels. Ruttner (1953) stated that temperature is one of the

factors which affect the concentration of oxygen. The attainment of

maximum levels of DO during winter month in the river might be due to

relatively low temperature of the water and sudden fall in DO value during

summer months could be due to general rise in temperature. In the present

study temperature was indirectly controlling the algal production as well as

meiofaunal community. Same observation was made by (Anand, 2002). The

maximum temperature was 29.60C at site-3 in Sept’09, the Epifloral

communities dominated by Ulothrix monliformis, Ulothrix zonata, Synedra

ulna, Synedra iconic, Synedra mazamaenis, Gomphonema sp, Gyrosigma sp,

Navicula ambigua, Cymbella minuta. Among faunal communities

Nematode, Ceriodaphnia silvestrii, Ceriodaphnia dubia, Difflugia sp,

Boleophthalamus dussumeiri and Neries sp were found.

Soil temperature at all sites was influenced with the water temperature

and atmospheric temperature. It is an important parameter and has impact

upon the community aggregation. In the present study, the maximum

temperature was recorded 28.60C at site-3 and site-1 in Sept’09 & Apr’10.

The Epifloral communities were represented by Melosira varians, Synedra

sp, Pinnularia sp, Cymbella sp, Scenedesmus longispina, Spirogyra sp,

Oedogonium sp, Cosmarium sp. While faunal communities were represented

by Tintinnopsis sp, Lecane signifera, Lecane obtuse, Lecane flexilis,

Ostracoda, Cladocera, Nematode and Boleophthalamus dussumeiri.

75

Gold and Morales (1976) found that temperature was not the only

factor for the succession of tintinnids. (Kimor and Wood, 1975) stated that

Adverse weather conditions, which induce turbulence and variable predation

rates, were also major contributors to the disappearance of the number of

algal groups.

Dissolved oxygen is very important pollution parameters, as they

indicate the degree of pollution in water. DO is one of the most important

parameters in water quality assessment and reflects the physical and

biological processes prevailing in the waters. Likewise other aquatic

organisms in the aquatic ecosystems are affected adversely during conditions

of decreased DO, its presence is essential to maintain the higher forms of

biological life in water and the effects of a water discharge in a water body

are largely determined by the oxygen balance of the system. Non-polluted

surface waters are normally saturated with dissolved oxygen. Oxygen can be

rapidly removed from the waters by the discharge of the oxygen demanding

wastes. Other inorganic reductants such as hydrogen sulphide, ammonia,

nitrates and other oxidisable substances also tend to decrease DO in water.

The concentration of oxygen also reflects whether the processes undergoing

are aerobic or anaerobic.

The present study reveals a reduction in DO content which was found

to be 1.3 mg/l at site-3 in Apr’09. The Epifloral communities dominated by

Gomphonema angutum agardh, Gyrosigma attenuatum, Gyrosigma

proceum, Pediastrum sp, Navicula sp, Ulothrix zonata, Melosira undulata,

Tabellaria sp. While faunal communities represented by Calanoidcopepod,

copepod, Cladocera, Ostracoda, Discorbis sp (foraminifera),

Boleophthalamus dussumeiri, Nereis diversicola. Blum (1957) and

Venkateswarlu (1970) stated that low values of dissolved oxygen was

usually associated with high organic matter. In the river Kali near

Mansurpur, Verma and Dalela (1975) had noticed that the high load of

76

organic matter present in the waste influences greatly on the oxygen budget

of the river and adversely changes the water and sediment quality.

DO is high during rainy season and is maximum during winter.

Periods of high temperature is nearly coincides with low oxygen content, a

feature noted by Gonzalves and Joshi (1946) and Singh (1960). The present

study reveals the same i.e., DO was found to be maximum 6.69 mg/l at site-1

in Jan’10, the Epifloral communities were dominated by Anabaena sperica,

Amphora sp, Melosira sp, Cocconeis placentula, Nostoc sp, Pediastrum sp,

Ulothrix monliformis, Pinnularia sp, Pleurosigma angutum. While the

faunal communities followed by Nematode, Ostracod cypris, Turbellaria,

Gastrotricha, Rotifera, Copepod, Helisoma sp, Vivipora sp and Turritella sp.

Cocconeis Placentula, was most abundant during this study. In several

studies these species seem to be common at nutrient rich, well oxygenated

sites (Steinberg and Schiefele, 1988., Hofmann, 1994., Silva-Benavides,

1994). Fabri et al., (1984) found that Cocconeis placentula was able to

tolerate moderately polluted conditions if oxygen saturation levels were

high. High amount of DO was recorded in winter due to the intensive

photosynthesis activity on the upper levels (Ganapati, 1962). The high

amount of DO enhance the growth of Anabaena sp. & Ulothrix sp. while

Nostoc sp was favored by moderate oxygen content of the river water.

Results showed that survival of Epifloral communities is directly

proportional to the dissolved oxygen. There was an increase in the algal rate

where the temperature was low and dissolved oxygen was high. In the

present study the less number of harpacticoid copepod and Ostracoda were

recorded, during the depletion of DO. According to Tietjen (1969), as he

observed death of harpacticoid copepod and Ostracoda in anoxic conditions.

BOD is one of the most important parameters used in almost all water

pollution studies to evaluate the impact of waste water on water bodies

which are toxic to the organisms, involved in the biological breakdown of

77

the organic matter. Materials, which may contribute to the BOD, include

carbonaceous organic materials useable as a food source by aerobic

organisms, oxidisable nitrogen derived from nitrites, ammonia and organic

nitrogen compounds which serve as food for specific bacteria. Water with

high BOD indicates the presence of decomposing organic matter and

associated increased bacterial concentrations that degrade its quality and

potential uses. A byproduct of high BOD concentrations can increase algal

concentrations which results from decomposition of the organic matter and

which form the basis of algal populations (Jamil, 2001). High values of

BOD at site-3 indicate the influence of domestic wastes or a cause of

anthropogenic in origin. When maximum BOD was found in Jan’10 at site-3

the Epifloral communities were Synedra elegans, Ulothrix sp, Gomphonema

gracile, Coscinodiscus sp, Surirella sp, Fragillaria intermedia, Fragillaria

crotonensis. While faunal communities were represented by Copepod,

Boleophthalamus dussumieri and Nereis diversicola.

COD is a purely chemical oxidation test device as an alternate method

of estimating the total oxygen demand of waste water. Generally low DO

value indicates high pollution and high COD values indicate the presence of

oxidisable organic materials in the water (Jamil, 2001). High level of COD

suggests a high level of organic pollution. In the present study fluctuations in

COD concentration was observed in site-1 than compared to site-2 and site-

3. COD found to be maximum 1747 mg/l at site-3 in Jan’10. Epifloral

communities were contributed by Synedra sp, Ulothrix sp, Gomphonema sp,

Melosira sp, Gyrosigma nodiferum, Gyrosigma proceum. While faunal

communities were contributed by Copepod, Nereis diversicola and

Boleophthalamus dussumieri. While when the COD (8.69 mg/l) was

minimum in the month of Feb’10 at site-2 the Epifloral communities such as

Pleurosigma directum, Gyrosigma sp, Amphora sp, Melosira undulata,

Synedra iconic, Synedra mazamaensis, Pinnularia viridis were found. While

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the faunal communities included by Ostracoda, Nematode, Cladocera,

Copepod and Nereis diversicola.

Hydrogen sulphide: The sampling station is located closer to a

sewage disposal site. Because of this there was an abundant supply of

nutrients and partly decayed organic material. The organic material content

clearly reflected the rich organic deposition of the sediments. According to

(Nybakken, 1988) water circulation practically ceases and the interstitial

habitat becomes anoxic, thus resulting in less number of meiofaunal

communities, which is also found in the present study. Similarly Govindhan

et al., (1983) also revealed moderate fauna in the Purna and Mindhola

estuaries and poor fauna in Ambica estuary.

Sulfide indicates the organic matter present in water (Shastree, 1991).

In the present study Sulphide was positively co-rrelated with the organic

carbon content and negative correlated with the lead. H2S content observed

to be highest 2.58mg/l at site-3 in Oct’08. Meiofauna at highest H2S content

reported were the Euplotes sp, Copepod, Cladocera, Discorbis sp and Nereis

diversicola which are representatives of the sulfide system where exposure

to sulfide is continuous but the oxygen content was remains scarce during

this period.

Organic matter percentage was influencing the water holding capacity,

because of the affinity of organic matter is high for water (Gupta, 2004). In

the present study organic matter found to be decrease with decrease in water

holding capacity. The organic matter from various sources (allochthonous,

autochthonous) in the sediment plays important role in the nutrition of the

benthic organisms (Gowda et al., 2009). Organic carbon content increases

with the increasing finer fractions and decreases with increasing coarse

fractions of sediment (Varughese et al., 2009). Same observation was cited

in the present study. Organic carbon from the soil forms another important

component in deciding the occurrence of meiobenthos. Mare (1942)

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observed that the difference in the density and distribution of the

meiobenthos co-rrelated with the levels of organic matter in the sediments.

Kandalaro (1984) found maximum density of the benthic copepod in the

sediments having high organic matter. However, Varshney et al., (1981) did

not find any co- relation between meiofaunal density and sediment organic

carbon. Ansari (1988) also observed inconsistent pattern between the

horizontal distribution of meiobenthos and organic carbon. In the present

study the meiobenthos showed a negative correlation with organic carbon

except for harpacticoid copepod. Present investigation shows that organic

matter was found to be maximum 13.56% at site-2 in the month of Feb’09,

the Epifloral communities were Pleurosigma angutum, Gyrosigma sp,

Amphora sp, Melosira sp, Synedra sp, Pinnularia sp. While when the faunal

communities were represented by Copepod, Ostracoda, Nematode and

Nereis diversicola. When the organic matter was found to be minimum

0.05% at site-1 in the month of Apr’09, the Epifloral communities

contributed by Gomphonema sp, Gyrosigma sp, Pediastrum boryanum,

Pediastrum simplex, Navicula palpebralis, Navicula radiosa, Ulothrix

monliformis, Melosira varians. Among faunal communities represented by

Copepod, Cladocera, Ostracoda, Gastrotricha, Kinorhynca, Sipunculid sp.

Chloride occurs naturally in all types of waters and waste water. In

natural freshwater, however, its concentration remains quite low and is

generally lesser than that of Sulphate concentration. Discharge of

Agricultural, industrial, and domestic waste water can contribute the

presence of chloride in natural water. During summer the values of chloride

concentration were very high whereas in the rainy season they remained very

low. Although in winter there was a gradual rise in the chloride content and

on the onset of summer the maxima was again attained. During the present

study the maximum values recorded is 14782mg/l at site-3 in the month of

Apr’10 the Epifloral communities dominated by Melosira sp, Synedra sp,

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Pinnularia sp, Cymbella lanceolata, Cymbella tumida, Scenedesmus sp,

Oedogonium sp, Tabellaria fenestrate. Among faunal communities

Nematode, Rotifera, Copepod, Boleophthalamus dussumieri and Nereis

diversicola were found. Chloride concentration was found to be lowest 11

mg/l during the month of Aug’08 at site-1 and the Epifloral communities

observed were Coscinodiscus sp, Anabeana scheremetievi, Oscillatoria

princeps, Synedra sp, Pinnularia viridis, Ulothrix sp, Eudorina sp,

Pleurosigma sp. While faunal communities represented by Nematode,

Ostracoda, Turbellaria, Rotifera, Copepod, Kinorhynca, Helisoma sp,

Vivipora sp and Turritella sp.. Thresh et al., (1944) pointed out that high

chlorides are generally indicator of large amount of organic matter in water.

It was observed that the chloride has a positive correlation with the hydrogen

sulphide content and in soil with the Sulphate concentration.

The chloride and Ammonical nitrogen in soil were recorded high as

compared to water quality, throughout the study period. Whereas the other

nutrients were recorded high in water quality. Recording the high salinity

during the summer season was due to the high rate of evaporation in the

shallow coastal area owing to high atmospheric temperature the same was

also cited by (Govindasamy et al., 1997). A direct correlation between

chlorides and water temperature has been observed in present investigation,

since both of them exhibits rise and fall almost identically.

For the benthic animals more important are the interstitial chlorinity or

salinity, between the mud particles (Mclusky, 1981). During the present

study the chloride concentration in soil was found maximum 9647 mg/kg at

site-3 during the month Mar’09 the Epifloral communities were dominated

by Gomphonema angutum Agarth, Gyrosigma attenuatum, Navicula

cuspidata, Navicula digitoradiata, Navicula radiosa, Pediastrum duplex,

Ulothrix sp, Nitzchia inconspicua, Nitzchia dissipata, Melosira sp. Among

faunal communities Brachionus calyciflorus, Brachionus plicatilis,

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Nematode, Euplotes sp, Foraminifera, Boleophthalamus dussumieri and

Nereis diversicola were found. Chloride concentration was found to be

lowest 6.99 mg/kg at site-1, during the month of Aug’09 the Epifloral

communities were dominated by Coscinodiscus sp, Anabeana sp,

Oscillatoria sp, Synedra sp, Pinnularia sp, Ulothrix sp, Eudorina sp,

Pleurosigma sp. While faunal communities were represented by Nematode,

Ostracoda, Turbellaria, Rotifera, Copepod, Kinorhynca, Helisoma sp,

Vivipora sp, Turritella sp.. It has been constantly shown that the interstitial

salinity varies much less than the salinity of overlying water, as a result of

slow rate of the interchange between them (Mclusky, 1981). The present

study is in conformity with this observation.

The most important source of ammonia is the ammonification of

organic matter. Occurrence of ammonia in the waters can be accepted as the

chemical evidence of organic pollution. The toxicity of ammonia increases

with pH because at higher pH most of the ammonia remains in the gaseous

form. The decrease in pH decreases its toxicity due to conversion of

ammonia into ammonium ions, which are much toxic than the gaseous form.

The ammonia is maximum in the rainy season and the seasonal variation is

almost identical in the aquatic system (Rao, 1955 and Zafar, 1964). In the

present study the peak concentration was observed during the rainy seasons,

and subsequently the values dropped down during the month of summer and

thus it was observed that the seasonal variation is more pronounced in the

present study than that of the spatial variation. It was observed that the

growth of Oscillatoria sp, Navicula sp was favored by high quantity of

Ammonical nitrogen. The growth of blue green algae was favored by low

content of nitrate and phosphate, while the maximum growth of Pediastrum

duplex and Scenedesmus armatus was observed in nitrogen and phosphate

rich water. It was concluded that several species showed interesting pattern

82

of succession in relation to pollution load while rest of the algal species

showed variable pattern.

Ammonia in the soil is considered as an important factor for the

distribution of community, it was found to be maximum in 299.22 mg/kg at

site-2 during the month of July’08 the Epifloral communities dominated by

Cyclotella glomerata, Coscinodiscus stellaris, Pandorina morum,

Scenedesmus sp, Pleurosigma directum, Tabellaria sp, Gyrosigma

acuminatum and the faunal communities were represented by Rotifer,

Ostracoda, Nematode, Cladocera. Higher concentration of ammonia in soil

did not contribute to high algal density, but it showed the high diversity in

sediments of Tapi. According to Vidakovic (1983) pollution plays a major

role in controlling density and distribution of meiofauna. He further added

that sewage tends to increase density and decrease the diversity of meiofauna

organism. The present investigation was same as cited above. When low

concentration of Ammonia was found in soil, the nitrite and nitrate nitrogen

was attained its maximum level. The Epifloral communities dominated by

Cyclotella sp, Coscinodiscus stellaris, Coscinodiscus granii, Pandorina

morum, Scenedesmus sp, Pleurosigma sp, Gyrosigma proceum. Among

faunal communities Rotifer, Ostracoda, Nematode, Cladocera, were found.

Discharge of domestic sewage and industrial wastes, containing

nitrogen and phosphorus compounds would ultimately result in increase in

nutrient levels. In the present study it is clear that nitrate concentration is

higher at site-2 and site-3 as compared to that observed at site-1., but

significant increase in the value and the peak value recorded was 4.78 mg/l

at site-1 during the month of Dec’09. The possible reason for this is the

anthropogenic waste, indicating the waste water discharges in or around

these regions, Domestic sewage also contains very high amount of

nitrogenous compounds. Run-off from agricultural field is also high in

nitrate contents. Nitrate concentration was found highest 4.78 mg/l at in the

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month site-1 in the month of Dec’09. The Epifloral communities represented

by Coscinodiscus granii, Coscinodiscus stellaris, Amphora sp, Melosira sp,

Synedra iconic, Synedra ulna, Pinnularia sp, Ulothrix zonata, Navicula

ambigua, Pleurosigma directum. Among benthic communities represented

by Rotifera, Copepod, Cladocera, Nematode, Ostracoda, Turbellaria,

Helisoma sp, Vivipora sp and Turritella sp.. While the minimum value of

nitrate concentration in water was observed 0.016mg/l at site-1 during

Mar’09 and as well as Mar’10. Epifloral communities contributed by

Coscinodiscus sp, Pandorina sp, Synedra sp, Pinnularia sp, Ulothrix sp,

Eudorina sp, Pleurosigma sp. Among faunal communities Rotifera,

protozoa, Copepod, Cladocera, Nematode, Ostracoda, Turbellaria were

represented.

Maximum nitrite concentration in water 3.217 mg/l was observed in

the month of Jan’09 at site-3. Epifloral communities were dominated by

Navicula sp, Oscillatoria sp, Pediastrum sp, Gomphonema sp, Gyrosigma

sp, Ulothrix sp, Melosira sp, Rhizosolenia sp. None of the species of

protozoa was found during premonsoon for both of the years of

investigation. During pre- monsoon period altogether 3 species of protozoa

were recorded throughout the study period and the species found were

Euplotes sp, Difflugia sp, Dipleptus sp. In winter period, only 2 species of

protozoa were recorded during the period of investigation and the species

found were Euplotes sp, Difflugia sp in which, Euplotes sp was dominant in

the 1st year of investigation. Among faunal communities Calanoidcopepod,

Nematode, Sipunculid sp, Boleophthalamus dussumieri, Nereis diversicola

were found altogether. While the minimum concentration 0.002 mg/l at site-

2 during the month of Jan’10 and Mar’10. Epifloral communities represented

by Coscinodiscus sp, Volvox sp, Melosira sp, Synedra sp, Cosmarium sp,

Ulothrix sp, Pinnularia sp, Pleurosigma sp. Among faunal communities

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Hexarthra sp, Oithono colcarva, Monia sp, Daphnia sp, Keratella sp,

Nematode and Nereis diversicola were found.

The nitrate concentration in soil is higher at site-1 as compared to that

of site-2 and site-3., but suddenly the value increased and the peak value

recorded was 60.43 mg/kg at site-1 during the month of Nov’09. The

Epifloral communities were represented by Coscinodiscus sp, Melosira sp,

Navicula sp, Oscillatoria sp, Gomphonema gracile, Gyrosigma sp,

Pediastrum duplex, Pediastrum boryanum. Among faunal communities

Copepod, Cladocera, Ostracoda, Helisoma sp, Vivipora sp and Turritella sp.

were found.

While the minimum concentration of nitrate in soil was 0.06mg/kg at

site-1 during the month of Nov’08. While at low values of nitrate

concentration, the abundance of the above group comparatively found to be

decreased.

Maximum nitrite concentration in soil was found 323 mg/kg at site-3

during the month of Nov’09. The Epifloral communities were represented by

Coscinodiscus sp, Gyrosigma sp, Pleurosigma sp, Nitzchia palea, Nitzchia

intermedia, Gomphonema sp, Ulothrix sp, Synedra sp, Spirulina subsalsa,

Thalassiosira sp. Among faunal communities Nematode, Copepod,

Cladocera, Rotifera and Nereis diversicola were found. While the minimum

concentration of nitrite in soil was 0.052 mg/kg at site-1 and site-3, during

the month of Jan’09 and Apr’09. The Epifloral communities were

represented by Navicula sp, Oscillatoria sp, Pediastrum sp, Gomphonema

sp, Gyrosigma sp, Ulothrix sp, Melosira sp. Among faunal communities

Calanoid copepod, Cladocera, Nematode, Boleophthalamus dussumeiri and

Nereis diversicola were found.

The total phosphorus concentration was chosen as the most important

productivity limiting (trophic) factors in inland waters. The prime concern of

phosphorus lies in its ability to promote the growth of nuisance algae and

85

eutrophication. Phosphorous as such is not harmful to the organisms. The

high values of phosphate during the rains may be due to the addition of

phosphate through drainage. The high values of phosphate may be attributed

to the formation or accumulation of inorganic phosphates and also to the

substantial addition of phosphate through agricultural drainage and sewage

from the neighboring areas (Blum, 1957). During the later part of the winter

and the early part of the rainy season, the phosphate content remained low.

In the present investigation, Maximum phosphate concentration was

recorded 3.64mg/l at site-3 during the month of Aug’09. Venkateshwarlu

(1976) observed that high temperature and more phosphate were favorable

for the growth of Scenedesmus armatus, while in the present investigation,

the maximum growth of S. armatus was observed at the moderate

temperature and high amount of phosphate. Epifloral communities

dominated by Navicula sp, Surirella gemma, Scenedesmus sp, Gomphonema

sp, Microcystis sp, Pinnularia viridis, Stauroneis javanica, Oedogonium sp.

Among faunal communities Nematode, Rotifera, Copepod, Boleophthalamus

dussumieri were observed.

Dissolved phosphates have been the most widely available form of an

inorganic phosphate for algal growth and with nitrate were reported as

limiting nutrients (Reynolds, 1998., Hobbie, 1974). A seasonal increase in

the concentration of nutrients was associated with inflow from water

drainage during the rains (Atoma, 2004). Kemdirim (2000) reported trace

composition during this period asserting that the rains helped to dilute

concentrations. Among faunal communities Nematode, Rotifera, Copepod

were observed.

The phosphorous in water is precipitated and lost to the sediments,

resulting in the overall decrease of phosphorous in water and increase in the

sediments (Habib, 2002). Present finding is in concurrence with the

observation of (Habib, 2002). Higher concentrations of phosphorous

86

recorded were 77.45mg/kg at site-1 during Feb’09. The Epifloral

communities dominated during this month were Coscinodiscus sp, Amphora

sp, Melosira sp, Synedra sp, Pinnularia sp, Hydrodictyon sp, Oedogonium

sp. Among faunal communities Cladocera, Nematode, Ostracoda,

Turbellaria, Rotifera, Copepod, Tardigrada, Helisoma sp, Vivipora sp,

Turritella sp. were present. While at the minimum concentrations which was

recorded 0.88 mg/kg at site-2, during the month of Mar’09. The growth of

Scenedesmus sp and other blue green algae Anabaena sperica, Anabaena

scheremetievi, Spirulina subsalsa, Oscillatoria sp were found and followed

by diatoms such as Gomphonema sp, Gyrosigma sp, Navicula sp. Among

faunal communities Nematode, Copepod, Cladocera, Rotifer, Nereis

diversicola were present. It was likely becomes limiting for a specific period

of individual development of fast growing rotifer (Elser et al., 2000). High

pollution load due to entry of sewage, eutrophication and heavy metals might

have led to the diversity of species in rotifers. Similar studies have been

noted in the present findings. Rotifers respond quickly to environmental

changes and are considered good indicators of water quality and trophic

conditions because of their short generation time and fast population renewal

(Pontin and Langley, 1993., Sladecek, 1983). Many author suggested that

both rotifers species composition and abundance could be used as indicators

of trophic state (Berzins and Pejlar, 1989., Matveeva, 1991., Duggan et

al., 2001).

During present investigation maximum Sulphate concentration was

2732.8 mg/kg at site-3 during the month of June’09. The Epifloral

communities dominated by Diatoms such as Coscinodiscus sp, Synedra sp,

Pinnularia sp, Ulothrix sp, Eudorina sp, Pleurosigma sp. Among faunal

communities Nematode, Rotifera, Copepod, Boleophthalamus dussumieri,

Nereis diversicola were present. Minimum Sulphate concentration was

recorded 5.85 mg/kg at the riverine zone of Tapi during the month of

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Aug’08. The Epifloral communities dominated by Coscinodiscus sp,

Anabeana sperica, Oscillatoria sp, Scenedesmus obliquus, S. quadicauda,

Pinnularia sp, Ulothrix sp, Eudorina sp, Pleurosigma sp, Nitzchia sp.

Among faunal communities Nematode, Ostracoda, Rotifera, Sipunculid sp

Copepod, Turbellaria, Helisoma sp, Vivipora sp, Turritella sp. were present.

The ecological significance of heavy metals as stressed by some

earlier workers (Keith and Telhard, 1979., Purves, 1985) could be due to

their toxicity and cumulative behaviour with serious public health

implications (Phillips and Rainbow, 1993). Unlike other pollutants they are

not biodegradable hence undergo a global ecobiological cycle (Nurnberg,

1984) in which natural waters are the main pathways. Benthic communities

like any other living population, are generally affected by the trace metals or

heavy metals. Although most metals are highly toxic and many hazardous

substances discharged into the aquatic environments are known to

accumulate in river or estuarine sediments and even accumulated in the

organisms, also over a period of time along a food chain (Forstner and

Muller, 1973). Normally sediments are not subjected to much variations

when compared to the overlying water body. Sediments act as traps for

various compounds in the aquatic system. Hence the analysis of sediments is

a good indicator of water quality (Forstner and Salmons, 1980). Thus, for a

proper understanding, it is necessary to analyze the bottom deposits for trace

metals (Iyer, 1994).

Of the three stations selected for the regular monitoring in the present

study, stations (1) recorded higher level for copper in the sediment during

post monsoon months and minimum level during pre- monsoon months. For

the other three stations values were relatively low and significant seasonal

pattern could not be observed. Copper is regarded as a wide spread pollutant

in industrialized estuarine areas and is relatively more toxic than other

essential trace metals. Rajathy & Azariah (1996) reported elevated levels

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of copper in the industrialized region of Ennor estuary during monsoon and

post- monsoon seasons. Whereas low values were recorded during the

summer months (Venugopal et al., 1982). There are a number of reports

regarding the fate of metals in estuarine waters (Gibbs, 1973., de Groot,

1973., Dunicker and Nolting, 1976). Maximum value of copper in soil was

recorded 128.43 mg/kg at site-2 during the month of Dec’08. Epifloral

communities contributed by Oscillatoria sp, Spirogyra sp, Ulothrix sp,

Melosira varians, Pediastrum sp, Navicula sp, Cymbella aspera, Cymbella

cistula, Gomphonema sp. Among faunal communities Copepod, Cladocera,

Ostracoda, foraminifera, Nereis diversicola were found. Minimum value of

copper in soil was recorded 0.306 mg/kg at site-2 during the month of

Aug’08. Epifloral communities contributed by Surirella gemma, Surirella

elegans, Navicula sp, Microcystis sp, Fragillaria crotonensis, Fragillaria

capucina, Rhizosolenia imbricata. On the basis of the above mentioned algal

species, it became clear that in changed habitat, the original community

struggle to register their presence whereas Rhizosolenia imbricata, a new

tolerant species would struggle to register its presence in these changed

condition of the habitat. So far the member of Bacillariophyceae is

concerned; only 3 species Navicula sp, Fragillaria capucina, Rhizosolenia

imbricata were recorded during the 1st

period of investigation, whereas in the

corresponding period of 2nd

year of investigation, this species Surirella

gemma, Surirella elegans, Navicula sp, Fragillaria crotonensis, Fragillaria

capucina, Rhizosolenia imbricata were recorded. Among the faunal

community Crustacean nauplius larvae, Acartia hudsonica, Ceriodaphnia

dubia, Brachionus plicatilis, Stenostomum sp were recorded.

The main sources of zinc in river water was refineries, galvanizing

process, brass manufacturing, metal plating, plumbing, construction

materials, dry batteries, pigments and printing processes (Arya et al, 2002).

Zinc concentration was found maximum 83.57 mg/kg at site-2 during the

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month of Feb’10. Epifloral communities contributed by Pandorina sp,

Gyrosigma sp, Amphora sp, Melosira sp, Synedra sp, Pinnularia sp. Among

faunal communities Ostracoda, Nematode, Cladocera, Copepod, Nereis

diversicola were found. The same benthos was found when the zinc

concentration was minimum 0.16 mg/kg at site-2 during the month of

Aug’08 as compared to minimum value of copper during the present

investigation.

Man’s continuous utility and exploitation of lead smelters, battery

manufacturing, paper and pulp industries, boat and ship fuels and

ammunition industries are important sources of lead contamination (Jamil,

2001). A seasonal distribution of lead in Cochin estuary was reported by

Nair et al., (1990). They recorded high values for lead during premonsoon

and post monsoon period but low values during monsoon. Jayasree and

Nair (1995) reported low concentrations of lead towards the freshwater zone

of Cochin estuary and they attribute this observation to the sandy nature of

the sediment as was proposed earlier by Zindge et al., (1998). However, in

the present investigation the maximum value of lead in soil was noticed

38.38 mg/kg at site-1 (upstream of Tapi River) during the month of July’08

and was not co-rrelated with the above findings. Epifloral communities were

represented by Melosira sp, Nitzchia dissipata, Anabeana sperica,

Oscillatoria sp, Synedra sp, Eudorina sp, Pleurosigma angutum. Among

faunal communities Nematode, Ostracoda, Turbellaria, Rotifera, Copepod,

Kinorhynca, Helisoma sp, Vivipora sp and Turritella sp. were found. When

the lead concentration was minimum 0.02 mg/kg at site-3 during the month

of Oct’08. Epifloral communities was represented by Navicula sp ,Surirella

sp, Cymbella cistula, Gyrosigma sp, Pinnularia sp, Stauroneis

phonicenteron. Among faunal communities Euplotes sp, Copepode,

Cladocera, foraminifera, Boleophthalamus dussumieri and Nereis diversicola

were present.

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Cadmium content although decreased with increasing depth of soil

profile, the adsorption was more at the surface than at the lower layers

because of higher content was retained by adsorption in mineral interface

and interaction with organic matter. The adsorption of metals by organic

matter was more at the surface due to higher content of organic carbon

(Sharma et al., 2004). Mostly Cadmium Concentration noted was below

detectable level, but was gradually recorded in post monsoon period, while

the maximum concentration was found (0.49mg/kg) at site-1 during the

month of Jan’09. The high incidence of cadmium might be a result of

anthropogenic sources mainly industrial and domestic effluents

(Ramalingam pillai et al., 1994). Main sources of cadmium effluents are the

cladding industry where it is used in protective metal coating, nuclear

reactors, alkaline cells and alloy industry (Jamil, 2001). Algae as Nitzchia

palea among diatoms and Nematode is a widely adaptable taxon on the state

of an aquatic environment. In this study, it was found that diatom had a

specific tolerance to heavy metals (Pb and Cd) in river water samples. The

result indicates that the higher is the concentration of heavy metal in the

river environment. Thus Algae as Nitzchia palea among diatoms and

Nematode can be used as bioindicators of heavy metal pollution. Therefore,

it was found that the diatom Nitzchia palea and Nematode had a tolerance to

heavy metals in river water, being able to live in such an environment. From

the viewpoint of both biological and chemical analyses, Tapi is still polluted

with heavy metals, because their concentration in the river samples was very

high. All these observations indicate that the tolerance to heavy metals by

various algae appears to be species specific irrespective of the type of their

habitat (Break et al., 1976). Coull and Wells (1981) observed that

Nematodes were dominant only in unpolluted sites. Observations by Hodda

and Nicholas (1985) showed that meiofaunal density decreased with

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increasing pollution. In the present study also, the marine Nematodes have

been found quite resistant to cadmium.

Brinkhurst (1970, 1972) and Cairns and Dickson (1971) have

advocated that the macrobenthic faunal study could provide useful

information about the pollution status as well as past and present water

quality conditions, since their life span is comparatively long, they quickly

respond to changes in Physico-chemical conditions, they have middle order

position in food chain and can be easily procured and preserved and handled

for experimental work. Further in addition to spatial variations the

meiobenthos inhabiting the intertidal zone also vary seasonally with the

Physico-chemical regime (Sunitha Rao, 2000). According to Chatterji et

al., (1995) the study of seasonal patterns of meiofauna provides information

on the productivity of the area. However Ingole and Paruleker (1988)

stated that the tropical estuaries subjected to distinct seasonality are

comparatively less studied for the seasonal variations than the temperate

estuaries. From the few seasonal studies of meiobenthos in the tropics the

significant influence of rainfall has been revealed (Alongi, 1987).

While the number of animals decreased during the pre-monsoon

period (March-June) leading to the seasonally natural mortality or

elimination of meiobenthos during the monsoon period (June-September),

the postmonsoon season (Sept-March) was characterized by increasing

number and biomass. In other words, the post monsoon season was the

period of benthic production during present investigation.

The abundance and species composition of meiobenthos are controlled

primarily by physical factors such as particle size of sediments, temperature

and salinity (Mcintyre, 1971). While this is true in a most general sense, it is

becoming increasingly clear that biological interactions, habitat

heterogeneity and predatory controls, play just an important role in

structuring the meiofauna assemblage (Coull and Bell, 1979). The long-

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term variations in the meiofaunal abundance are small, but seasonal changes

are quite pronounced (Ansari and Paruleker., 1998).

Most of the fauna were absent during the (June-Sept) and few species

were replenished during the month of Jan’09. Species richness and

abundance increased from post to pre-monsoon (Feb-May). There were

distinct seasonal differences in the occurrence of particular species and their

abundances.

Thus other factors such as water dilution, current velocity, and

possible changes in nutrient quality may account for the seasonal variation of

density with seasons. It is therefore reasonable to suggest that despite the

nature of sediment, that the overlying water has measurable influence on the

quality of the sediments, which subsequently affects the fauna dwelling

therein. It is also possible that other density dependent factors such as intra

and inter-specific competition may reduce the number of individuals in such

sediments in wet season.

There are three main constituents of soil: organic matter, air, water.

The organic matter is derived mostly from decaying vegetable matter which

is broken down and decomposed by the action of the many different forms of

animal life, which live in the soil. The role of organism in soil formation is

of critical importance for without life there can be no soil formation. While

normally both air, and water occupy the spaces between the structures of the

soil, but if a soil is saturated with water most of the air is driven out

(Bridges, 1970).

Porosity, water-holding capacity, texture are fundamental physical

properties of sediments. A measurement of these properties is rapid,

inexpensive and highly reproducible (Whalley, 1980).

Results for texture shows that texture remained similar throughout the

sampling period. The sediments in the mud bank in intertidal region of the

Tapi estuary were observed to be thinly distributed. The superficial layer of

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the muds that deposited, on the underlying hard substrate were limited to less

than 10 cm, below this 10 cm the substrata were very hard and completely

blackish in nature. It shows that the oxygenated region in the intertidal

region of Tapi estuary were restricted only in the superficial layers because

of this the meiofaunal communities had a very limited area of survival. The

superficial layer of sediments was clayey in nature and hence very unstable.

There are chances for meiofaunal communities to get washed away from

unstable substrata due to the turbulence along with high tide.

According to Ansari (1988), organisms are important in controlling

sediments fabrics by their burrowing and feeding activity. It is not

unreasonable to expect a strong biological influence on sediment porosity,

water content, cohesion and compaction. Medium size particles play an

important role in the distribution of meiobenthos. Certain taxa, genera and

species are restricted to a particular sediments type. Preference of different

species and taxa to different grain size has been confirmed experimentally by

(Tita et al., 1999). Small difference in grain size composition alters the

porosity and permeability of sediments which in turn affects the oxygen

content and animals that live in (Nair and Govindakutty, 1972). Thus

Jansson (1967) regards the grain size composition as the ‘Super- Parameter”

for sediments living fauna. In present study, site-1 mainly consists of Loamy

sand in texture of which soil materials containing 70-90% sand, 0-30% silt

and 0-15% clay. As such, they resemble sands in that they are loose and

single grained and most individual grains can be seen and felt. Because they

do not contain slightly higher percentage of silt and clay than do the sands.

At site-2 and site-3, mainly consists a sandy loamy in texture. A Sandy loam

consists of soil materials containing somewhat less sand, and more silt plus

clay. As site-2 shows an increasing trend from the river to the middle region

of the Tapi and thereafter site-3 was marginally declining towards the

seaward end. But on the whole despite the fluctuations, the trend was

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increasing from freshwater towards the Seaward end. During present

investigation, site-2 i.e., estuarine sediments of the region due to their finer

grain size contains more clay minerals and organic matter. However, organic

carbon exhibited positive correlation to silt and clay fractions, while negative

correlation with the sand composition.

During present study, the Polychaeta were found in site-2 and site-3.

This may be due to the texture of the sediments. Gowda et al., 2009 reported

that polychaete found to prefer fine to medium type of sandy bottom with the

admixture of silt and clay.

Regarding the biological characteristics of the sediments, highest

number of Polychaete were recorded in April’09 and May’09 at site-2.The

peak value of Polychaete was observed in Feb’09 at site-3. While maximum

value of polychaete was observed during post monsoon period in site-2 and

site-3. Similar type of polychaete abundance was observed in Zuari estuary

and brackish water pond of Nethravati estuary by Gowda et al., 2009.

Macrofauna Boleophthalamus dussumieri (mud skipper) was recorded

at site-3 throughout the study period. This may be due to the presence of

muddy substratum and the detritus as organic food. Similar observation was

cited by Desai., 1997.

Molluscan were found in site-1 (Fresh water zone) monsoon and post

monsoon season till Feb’10. The Species richness was dominated by

Helisoma sp, Vivipora sp, Turritella sp.. While crab was found only during

rainfall period during June & July’08 at site-3. Whereas at site-2 during the

month of July’08 & Sept’08.

Soil bulk density is defined as the ratio of the mass of oven dried

solids to the bulk volume of the solids plus pore spaces. The pores are

occupied by the liquid and gas. These air and water filled pores vary

reciprocally with the moisture content of the soil and are indirectly depend

upon the texture and structure (Gupta, 2004). In the present study it was

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found that when bulk density was minimum, the value of pore space found to

be maximum. Bulk density was found highest 1.92 g/cm3 at site-3 during the

month of Oct’09. The Epifloral communities were represented by Cyclotella

sp, Gomphonema sp, Gyrosigma sp, Pediastrum sp, Navicula sp, Ulothrix

sp, Melosira sp. Among faunal communities Rotifera, Copepod, Cladocera,

Nematode were present. Bulk density was found minimum 1.02 g/cm3 at

site-2 during the month of July’08. The Epifloral communities contributed

were Volvox sp, Cymbella sp, Surirella sp, Navicula sp, Microcystis sp,

Gyrosigma sp, Fragillaria and Oscillatoria sp. Among faunal communities

Nematode, Scapholebris ramneri, Bosminia sp, Daphnia sp, Centropyxis sp,

Lecane sp, Keratella sp were found.

Particle density of the soil refers to the density of the solid particles

collectively. It is the ratio of the total mass of the soil particles to their total

volume, excluding pore space between particles (Gupta, 2004). During

present investigation there was a positive correlation found particle density

with that of moisture content. When particle density found maximum 2.85

g/cm3 at site-3 during the month of Mar’09. The Epifloral communities were

represented by Gomphonema angutum Agardh, Gyrosigma proceum,

Navicula palpebralis, Navicula radiosa, Pediastrum sp, Ulothrix sp, Nitzchia

dissipata, Melosira sp. Among faunal communities Brachionus calyciflorus,

Brachionus plicatilis, Nematode, Euplotes sp, Foraminifera, Boleoph-

thalamus dussumieri were found.

Minimum value of particle density was found 2.15 g/cm3 at site-1

during the month of Oct’08. The Epifloral communities were represented by

Coscinodiscus stellaris, Navicula sp, Pediastrum simplex, Rhizosolenia

hebata, Gyrosigma sp, Melosira sp. Among faunal communities Monostyla

sp, Lecane sp, Nothalca sp, Ostracode cypris, Gastrotricha, Tardigrada,

Helisoma sp, Vivipora sp and Turritella sp. were present.

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Pore space in soil consists of the soil volume which is not occupied by

solids. The volume of sediments occupied with water is known as liquid

phase or capillary porosity. These values are not constant but vary with the

soil’s physical condition and moisture content (Gupta, 2004). Pores in soil

are the result of irregular shapes of primary particles, and their aggregation,

worms, and insects and of expanding gases entrapped by water. Clay soil

may have 50 to 60 % pore space. Whereas, sandy soils have low pore space

of about 30 percent. Clay and clayey soils have a greater number of micro or

capillary pores, in which water can be held tighter in small pores than in

large ones. When pore space was found maximum 56.03 % at site-2 during

the month of July’08.The Epifloral communities were represented by Volvox

aureus, Cymbella cistula, Surirella sp, Navicula sp, Microcystis sp,

Gyrosigma sp, Fragillaria sp and Oscillatoria sp.

Among faunal communities Nematode, Scapholebris ramneri,

Bosminia sp, Daphnia sp, Centropyxis sp, Lecane sp, Keratella sp were

observed. When pore space was found minimum 23.93% at site-1 during the

month of May’09. Epifloral communities were represented by Coscinodiscus

sp, Navicula sp, Amphora sp, Melosira sp, Synedra sp, Pinnularia sp,

Hydrodictyon sp, Scenedesmus sp, Oedogonium sp. Among faunal

communities Rotifera, Copepod, Cladocera, Nematode, Ostracoda,

Turbellaria were found.

Water Holding Capacity is controlled primarily by soil texture and

organic matter. Thus a soil with high percentage of silt and clay particles,

has a higher water holding capacity. Also it was found that there is a positive

correlation between WHC and organic carbon. Maximum water holding

capacity was recorded 64.73 % at site 2 during the month of Aug’09 the

Epifloral communities were recorded Navicula sp, Surirella sp, Cymbella sp,

Gomphonema sp, Gyrosigma sp, Pinnularia sp, Stauroneis sp. Among

faunal communities Nematode, Rotifera, Copepod, Boleophthalamus

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dussumieri and Crab. While when the minimum water holding capacity was

recorded 24 % at site-1 during the month of Apr’09. The Epifloral

communities were recorded Fragillaria sp, Pleurosigma sp, Cymbella sp,

Coscinodiscus sp, Amphora sp, Cocconeis sp, Pandorina sp. Among faunal

communities Copepod , Ostracoda, Nematode were present.

Moisture of all the three sites was predominantly within the range 40-60% in

range. Moisture content of soil was maximum 52.63% at site-2 during the

month of Apr’09.

The Epifloral communities were found to be Gomphonema sp,

Gyrosigma sp, Pediastrum sp, Navicula sp, Ulothrix sp, Melosira sp. Among

faunal communities Copepod, Cladoceran, Ostracoda, Nematode were

recoded. When moisture content of soil was minimum 40.64% at site-1

during the month of Oct’08. The Epifloral communities represented by

Cosconodiscus granii, Coscinodiscus stellaris, Navicula sp, Pediastrum sp,

Rhizosolenia sp, Gyrosigma sp, Melosira varians. Among faunal

communities Monostyla sp, Lecane sp, Nothalca sp, Ostracode cypris,

Gastrotricha, Tardigrada, Helisoma sp, Vivipora sp, Turritella sp. were

found.