INTRODUCTION:

A number of researchers in the early part of the 19th Century published data on fresh water ecology; the important ones being Pearsall (1922) who interpreted the factors influencing the distribution of free floating vegetation and indicated it as a valuable asset in the study of plankton. The most influential limnologists that followed him were Patrick (1948), Prescott (1948), Andrews (1948), Schultz (1952), Round (1953), Zeelar (1953), Wright (1954), Gerloff and Skoog (1957), Evans (1958), Paterson (1960), Talling and Driver (1963), Wilson (1963), Copeland and Whitworth (1963), Woodson and Holoman (1964), Lind (1965), Davis (1956), Kemmerer and Narhold (1969), Muzino and Moris (1970), Morgan and Margaret Kalk (1970), Marcos and Mohalis (1970), Kilham (1971) and Lind (1938). Limnological studies on the Indian fresh water bodies were not known until 1916. Iyengar (1940) worked on algal flora of some rain water pools. Philipose (1960) worked on the periodicity of algae. Ganapathi's (1940) work on pollution and related growth of temple ponds; Gonzalves and Joshi (1946) on algal ecology, Saxena (1955) on the occurrence of Euglenaceae, and Singh (1960) on phytoplankton ecology are all land marks in the study of ecology.

During the later period many significant publications appeared; the important ones being those of Rondhawa (1936) on the distribution of fresh water algae, Das and Srivastava (1955-56) on the correlation of plankton to the hydrological factors; Shrebuvarsan (1963) on primary production of lakes, Zafar (1959-67) on the limnology of lakes, Khan and Quayamm (1966) on the ionic composition of fish ponds. Srinivasan (1970) on the limnology of tropical impoundments, and Rao (1971-72) on the ecological studies of fresh water ponds. The work of Munnawar (1972) and Seenayya (1973) on polluted and unpolluted environments are of interest. Rao (1971-72), Hosmani and Bharati (1980), Hosmani and Naganandini (1992) have done significant work on fresh water bodies.

Most of these works only deal with physico-chemical parameters operating in a particular body of water, while some have discussed the distribution of unicellular and colonial organisms. Biochemical aspects of water pollution have not received much attention in India; although physico-chemical parameters have been dealt in many water bodies. This would give a comprehensive picture of what exactly is going on inside a water body. In fresh waters, dissolved organic matter plays a significant ecological role and exhibits relationships with organisms that produce, transform and use it. The phytoplankton liberates carbon newly fixed in photosynthesis into the external medium in the form of dissolved organic matter (Wilson 1963). This excreted organic material is an effective substrate for the growth of different microorganisms including algae.

MATERIALS AND METHODS:

Biochemical aspects of water pollution in two water bodies of Mysore city were studied for a period of two years. They are situated about five kilometers apart. They differ in size, shape, depth, aquatic vegetation, degree of pollution and also in the physicochemical nature of the water. Dalvoi lake receives continuous inflow of domestic sewage from the city. Kukkarahalli lake once received waste from the city but the inflow was stopped later. The soil in and around them is lateritic. The lake is disturbed to a great extent by animal and human beings. These two water bodies are heavily polluted based on the activities in and around them. The liberation of extra cellular products by the plankton and their significance is discussed for the first time and there is absolutely no record of such studies form this region.

Samples were collected monthly from both the water bodies for physico-chemical, biochemical, phytoplankton, zooplankton and bacterial estimations. These samples were later processed and the plankton enumerated in them. Phytoplankton, zooplankton and bacteria were correlated for the occurrence of physicochemical and biochemical complexes (Al.Hassan, R.H. and S.J.Coughlan, 1976). As a result, certain interesting correlations were observed. Standard methods were used in the determination and enumeration of the data. Detailed account of the methodology is provided in the reference - Hosmani et al., (1999).

RESULTS AND DISCUSSION:

To arrive at precise conclusions, a correlation matrix between each parameter and inter correlation matrix between the plankton, physico-chemical and biochemical parameters were derived. The results presented in Tables 1 to 6 are discussed below.

PHYSICOCHEMICAL COMPLEXES:

Distinguishing the effects of physical and chemical parameters on the natural phytoplankton communities remains a major problem. Discussions are based on grouping associated parameters and their inter-relations and their effect in regulating biochemical properties as well as plankton population. Air and water temperature does not differ significantly, and minor variations between them are a result of the different water levels during various seasons. Sunshine affects temperature directly, whereas sunshine and temperature together increase the carbon dioxide content; while rainfall seems to favour higher concentrations of oxygen. Hydrogen ion concentration and carbon dioxide vary inversely in the water bodies. The total alkalinity is very high in Dalvoi lake mainly because of the inflow of regular sewage increasing the hydrogen ion concentration. Since Kukkarahalli lake receives no inflow of sewage presently, the total alkalinity is low and the hydrogen ion concentration of this water is less alkaline. Phosphates and dissolved oxygen are interrelated and phosphates are present in relatively small amounts, which are subjected to wide variations. Dissolved oxygen and phosphorous show an inverse relationship.

Both the water bodies have an abundance of albuminoid ammonia and lower amounts of nitrates. The death and decay of enormous amounts of plankton in these waters and their rapid decay may be the probable reason for the high amounts of albuminoid ammonia recorded. Chlorides are low during monsoon months but are in considerable amounts during the other seasons of the year. Their increase is attributed to regular disturbances - the pollution being of animal origin. Biological and chemical oxygen demands are measures of active decomposition taking place in the water body. They are at the lowest recorded in both water bodies indicating rapid decomposition of organic matter. Oxygen and carbon dioxide are not inversely proportional. Carbon dioxide is completely absent in Kukkarahalli lake indicating that respiratory rate is higher than the photosynthetic rate because of the continuous existence of thick blooms in the water. Both these gases in Dalvoi lake indicate partial inverse relation at certain times mainly because the water is not allowed to stabilize due to regular inflow of domestic sewage. Total dissolved solids and hydrogen ion concentration show an inverse relation between them. The fact that alkaline waters have more total dissolved solids is not true in the present observation. Total alkalinity in Kukkarahalli lake is not very high, whereas, it has reached maximum levels in Dalvoi lake.

DISTRIBUTION AND PERIODICITY OF PHYTOPLANKTON:

In order to understand the interrelations between planktonic groups in these water bodies, they were considered separately which would give a better understanding of their distribution and periodicity.

Chlorococcales in general react to wide variations in physicochemical complexes. The maximum number recorded during this study is 1932 organisms/litre in Dalvoi lake during the summer months represented by species of Scenedesmus. It can be said that Chlorococcales can tolerate extremities in physicochemical complexes and they appear in all types of water bodies irrespective of the type of water they habitat. Yearly averages of Chlorococcales indicate that they are more in Dalvoi lake and less in Kukkarahalli lake. They were high during the second year of study and were low during summer months in Kukkarahalli lake. A total of 14 species of Chlorococcales were observed during the course of this study. Of these, five species belong to Scenedesmus. Dalvoi lake showed the maximum number of species. Their periodicity was not well marked and occurred when the physico-chemical complexes deviated greatly from the normal.

The physicochemical complexes do have certain correlation with the periodicity of Euglenaceae and indicate that they do not follow a definite pattern in the present study. Some species appear abruptly, give way to a unialgal or multi algal Euglenaceae bloom almost instantly and sometimes remain unseen from the surface water for a long duration. Species that occurred in one water body did not appear in the other except for a few and therefore it is difficult to assess the periodicity of Euglenaceae. Before the formation of blooms, the oxygen/carbon dioxide ratio is very low and gradually increases during the bloom and reaches a high value after the bloom indicating a high rate of photosynthesis as well as respiration during the bloom. Generally there is neither a precise rhythm nor correlation in the occurrence of these organisms. Of the two water bodies, Dalvoi supports higher numbers towards summer months and decreases slowly towards monsoon months. Euglenaceae in Kukkarahalli lake are poorly represented in diversity but has higher total counts; while Dalvoi lake supports a wide variety of species of Euglenaceae indicating it is contaminated to a greater extent than Kukkarahalli lake. The sporadic behaviour of Euglenaceae does not point out any physicochemical factor to be a critical criterion.

The amount of sunshine, phosphate, nitrate, oxygen and carbon dioxide have a significant effect on the growth of Myxophyceae. Temperature seems to play a less important role in the present study. Myxophyceae are quantitatively rich in both the water bodies, Microcystis aeruginosa being the dominant species in Kukkarahalli lake. The maximum peak of the blue green algae is observed during the summer months. Myxophyceae in general do not present a marked periodicity. Other species that occurred with Microcystis aeruginosa was Merismopedia tenuissima. Microcystis aeruginosa was the only common species that dominated these water bodies during various seasons which is an indication of the fact that it has a wide adaptability to all types of waters.

The abundant presence of blue-green algae has an antagonistic effect on the occurrence of desmids. The water bodies have high Myxophycean population and low desmid population. Secondly, the diversity of Chlorococcales seems to be high but the total number is low and both these algal groups have a role in reducing the number of desmids in the lakes. Kukkarahalli Lake represented only three species, mainly Closterium lunula, Cosmarium margaritatum and Staurastrum tetracerum and a few others that had no definite periodicity. Dalvoi lake represented only Closterium lunula indicating the high intensity of pollution in the water body. Desmids are poorly represented in both the water bodies.

Diatoms are controlled by many factors like pH, nitrate, phosphate, carbon dioxide and oxygen (Hosmani S.P. and L. Vasanth Kumar, 1996). Some prefer these in lower concentrations while others prefer them in higher concentrations. The water bodies under study support a poor diatom population, represented by Cymbella sps. Synedra ulna, Navicula rhomboides and Navicula sphaerophora.

The phytoplankton and zooplankton population is poorly related and the percentage occurrence of these shows that zooplankton is only 2% while the remaining 98% is phytoplankton. Zooplanktons are more in Kukkarahalli lake compared to Dalvoi lake.

The two water bodies have high amounts of faecal contamination and are far from being potable, but can act as a storehouse of organisms that produce H2S, which may include forms of salmonella, Proteus, Citrobacter and some strains of Klebsiella. The H2S strip test is significantly useful for screening water sources such as Kukkarahalli lake and Dalvoi lake, which have high faecal contamination.

BIOCHEMICAL PARAMETERS:

Algae in their natural habitat excrete polysaccharides into the medium they grow in. Healthy cells liberate these products and not injured, dead or decaying cells. Kukkarahalli lake has higher concentration of carbohydrates compared to Dalvoi lake. They vary from a minimum of 0.07mg/ml to a maximum of 0.19 mg/ml. An increase in the nitrogen content decreases the amount of total carbohydrates. The accumulation of carbohydrates is found to increase only after cessation of the exponential growth of algal blooms. Kukkarahalli lake supports a bloom of Cyanophyceae throughout the year and hence this may be one of the reasons for the high amounts of extra cellular carbohydrates in its water.

The glycollate excrete may directly reflect the growth and photosynthetic activity of phytoplankton (Viccaro.J.P. and E.L. Ambye, 1972). The amount of glycolic acid recorded in these waters was at an average concentration of 0.25 mg/ml in Kukkarahalli lake and slightly low (0.20 mg/ml) in Dalvoi lake. Glycolic acid liberated is high in Kukkarahalli lake in which the amount of carbon dioxide is almost negligible. While in Dalvoi lake the carbon dioxide content is high wherein the quality of glycolic acid is reduced. Other algae and bacteria are capable of utilizing excreted glycolic acid as a carbon source. The fluctuations in phytoplankton population can be partly accounted by the amount of extracellular products liberated.

The occurrence of Microcystis aeruginosa and occasionally Spirulina nordstedtii as permanent blooms and their death and decay accelerate the growth of other forms. In doing so the quantity of phycobiliproteins increases. Phycobiliproteins are high in Kukkarahalli lake. Dalvoi lake on the other hand supports a diverse plankton population mainly constituted by the members of Euglenaceae and has comparatively lower quantity of extracellular phycobiliprotein. Albuminoid - nitrogen is high in both the lakes and the total protein quantity is also high. This may be due to a large number of Myxophyceae liberating total proteins that is more pronounced in Kukkarahalli lake. Greater the saprobic nature, greater is the amount of chlorophyll liberated in a waterbody. The amount of chlorophyll in Kukkarahalli lake is less compared to Dalvoi lake. As both the waterbodies are contaminated with sewage, the planktonic population is high; the waters have sufficient quantities of extracellular chlorophyll in them.

A seasonal relationship between the occurrence of phytoplankton and the biochemical parameters indicates decrease in Euglenaceae and Chlorococcales members, which results in increase of glycolic acid, phycobiliproteins, total proteins and carbohydrates, while chlorophyll decreases to a certain extent (Writtingham, C.P. and C.F. Pritchard, 1963). The relationship of diatoms and desmids to other factors was not taken into account as they are absent throughout the year in Dalvoi lake but appear occasionally for a few months in Kukkarahalli lake. However, their importance is discussed in the correlation matrix.

The correlation and inter correlation matrix which is a statistical derivation taking into account all the parameters studied, indicates that the group Chlorococcales is a dependent factor and is controlled by the amounts of total alkalinity, water temperature, dissolved oxygen and chlorides. Chlorococcales are inversely proportional to certain physicochemical factors. Euglenaceae are dependent upon nitrate, total dissolved solids and nitrites where as Escherichia coliform and total bacteria are independent factors.

The regression analysis indicates that the liberation of carbohydrates is dependent on the number of diatoms, desmids and bacterial population. The activity of Chlorococcales and Myxophyceae reduce the growth of desmids. Total proteins and phycocyanin are the most prominent parameters and show negative association to chlorophyll. Euglenaceae are the most significant factor and are dependent on nitrite, total dissolved solids and phosphates.

CONCLUSION:

Both lakes are highly productive, one in terms of biochemical productivity (Kukkarahalli lake) and the other in terms of plankton productivity (Dalvoi lake). The total richness of chemicals, which may be the result of extracellular products liberated by the death and decay of algal blooms common in both water bodies, accelerates the occurrence of blooms (Euglenaceae and Myxophyceae). These in turn respond to the biochemical concentration of waters. Dalvoi lake is rich in the number of species while Kukkarahalli lake has a few individual species in abundance. Myxophyceae and Euglenaceae are inversely proportional. When plankton growth is abundant, the biochemicals are low and vice versa.

Both the water bodies have high electrolytes, low dissolved oxygen, relatively high phosphates and nitrogen and show a quantitative abundance of plankton with variable quantities and occasional occurrence of blooms. Myxophyceae are the most abundant.

Exploitation of algae for biotechnological products occurs in established and new businesses. Knowledge of algal polysaccharides continues to grow. Several new businesses process phycobiliprotein pigments from algae for use as sensitive fluorescent dyes and immunochemical reagents, and clinical diagnostics have been developed (Perdomo. J. 1986). As many as 40 diagnostic applications using phycobiliproteins have been developed to date. They are extremely efficient fluorochromes and function at wave lengths compatible with existing light sources, and they can also be used in multiple colour analysis. Application of glycolic acid in tanning industry for determining the quality of skin in fixing the dye and polishing metals along with other acids is in practice. Glycolic acid is also used in dyeing of wool and acid dyes for nylon. The oil soluble chlorophylls are widely used for food cloning, canned products and confectioneries. All these features indicate that the two water bodies are highly eutrophic and harbour a large number of plankton that liberate useful extracellular products and hence a 'PHYCOTECHNOLOGICAL' approach to these waters seems appropriate.

REFERENCES: