Lakes – Biodiversity and Sustainable management with special reference to the lakes of Mysore

Mathew Thomas Principal, St. Thomas English Medium School , Vishweshwaranagar, Mysore – 570 008 A. G Devi Prasad Senior Lecturer, Dept. of Environmental Science, University of Mysore , Mysore – 570 006

SYNOPSIS

    The knowledge about the biodiversity of lakes along with its present conservation status will help in the wise-use of these lakes, enabling in their sustainable utilisation, for the benefit of humankind in a way compatible with the maintenance of its natural properties. Basic information about its biological diversity and integrity, factors influencing their variety and variability, ecological contents and complexes will develop environment-sensitive behaviours. The integrity of these ecosystems, its ability to sustain diversity, productivity, self-repair and self-organisation can be preserved over time by ecological understanding and skillful actions. The foremost significance necessary to prevent degradation of lake ecosystems is to maintain its biological integrity and health. Biological assessment and monitoring of its resources is necessary for sustaining its integrity. The biotic components that supports rich biodiversity which includes the phytoplankton, zooplankton, macrophytes, fishes, macro-invertebrates and birds are under threat in most of the lakes due to anthropogenic pressure. Proper awareness programmes and education in about environment is necessary to protect the lakes. The vast potentials of the lakes when used judiciously and sustainably will prevent the undesirable degradation of the lake ecosystems. For successful implementation of sustainable development of the lake systems, it is necessary to practice favouring steps and procedures like environmental status assessment, environmental impact evaluation and environmental planning. Environmental-friendly practices and environmental-sensitive attitudes are the key for sustainable development of the lake systems.

1. INTRODUCTION :

    Lakes are a dynamic inland aquatic system that supports and maintains a balanced adaptive community of organisms having diverse species composition, and the functional organisation of all the organisms support a unique biotic integrity. Lakes, the major life supporting systems, are facing ecological degradation today, due to undesirable anthropogenic activities. The undesirable activities and unscientific utilisation of resources from the lakes have caused undesirable environmental problems, thus threatening the biodiversity sustained by it. It is again important to note that these species-rich aquatic ecosystems are capable of self-maintaining, however the delicate equilibrium is sensitive to external stimuli such as human activities promoted by socio-economic goals. Exercising a control on the prevailing anthropogenic activities is necessary to sustain these socio-economically and bio-aesthetically important aquatic ecosystems. These aquatic ecosystems representing the highest levels of ecological integration clearly emphasises the obligatory relationships, interdependence and interactions. The rich biodiversity sustained by nature in these lakes is as a result of the interweaved functioning of several complex factors. Limnobiotic status of certain lakes as studied by limnologists showed that several physical, chemical and biological factors act simultaneously to influence the biotic fluctuations.

    Adequate information about the various components, influencing parameters and the delicate dynamics sustained by them is of supreme importance to formulate appropriate environmental management strategies and protect the rich biodiversity of the lakes. Thus, for stable management of these lakes which have greatly influenced the progress of human societies since times, they have to be investigated in detail, specially to know its structure and ecological dynamics. Concrete steps should be taken to understand the complex interdependencies among physico-chemical parameters of the water, population dynamics of organisms, impacts of external influences, so that awareness about its dynamics and ecological values can be created among the public. It will greatly enable in better ecosystem management, and in sustaining its biodiversity and utility over long terms.

2. LAKE STRUCTURE AND DYNAMICS

    The physico-chemical factors and the biota it supports, source of water and its movement, interaction of environmental factors with the biotic components and its nutrient status and productivity constitute the lake structure. Understanding how these freshwater system functions is complex because of the interdependencies among chemicals in these waters and sediments, dynamic population of organisms, the changes in the nature of the surrounding landscape. In the lake ecosystems, the material cycles and energy flow is specially capable of self-maintaining. The natural equilibrium though very delicate is in self-correction mode and all materials, organisms greatly interact and influence each other, thus sustaining homeostasis. However, this equilibrium maintained is sensitive to external influences which can reach it to a stage of total collapse if man exerts undesirable pressure. Knowledge about the delicate dynamics between the biotic and abiotic components being influenced by the climatic factors along with the understanding of the various complex functions in the lake system is necessary for implementing all conservation measures.

3. PHYSICO-CHEMICAL PARAMETERS

    As stated by Prescott (1948), if any of the ecological factors can be regarded as more important, it would be the physico-chemical factors and others are only next to them. The physico-chemical study of the lakes enables in drawing out vital conclusions regarding the eutrophic status of these waterbodies. Limnobiologists have always considered that the study of physico-chemical status of the lake water is an indispensable study that will specify the relationships, interdependencies and interactions functioning in these ecosystems. With respect to the abiotic factors, it is noteworthy to mention that in lake ecosystems, there is significant direct and inverse relationship between the physico-chemical parameters, and it further influences the plankton fluctuations in these waters.

    The vital physico-chemical parameters like water temperature, pH, electrical conductivity, total hardness, total dissolved solids, total alkalinity, dissolved oxygen, free carbon dioxide, BOD, COD, calcium, phosphates, magnesium, nitrites, nitrates, ammonia-nitrogen, sulphates and bicarbonates decides the physico-chemical environment of the lake waters. These physico-chemical parameters are analysed by some standard methods given by APHA, IS, Trivedy and Goel. The investigation of these parameters enables in establishing important relationships, specifying the influence on the planktonic communities and other organisms and in drawing out vital conclusions regarding the eutrophic status of these waterbodies. The physico-chemical complexes exerting some vital influences on the plankton and also interrelationships between them can be best indicated from statistical analysis. Statistical methods like Pearson’s correlation matrix, Hierarchical cluster analysis, Principal component analysis (PCA), and Canonical correspondence analysis (CCA) significantly establishes relationships between variables. Pearson’s correlation matrix helps in forming clusters with linked parameters, hierarchical cluster analysis indicates the linkage between similar parameters, and dendrogram obtained shows percentage of similarities between the parameters. Factors of complex nature operating in these waterbodies can be best interpreted by utilising these statistical analysis. Several positive and negative correlations between parameters enables in drawing out the type of internal influences operating in these waterbodies.

4. ECOLOGICAL DEGRADATION OF LAKES

    Anthropogenic activities just for socio-economic benefits, higher greed to flourish at all expenses of the nature has continuously exerted unwanted pressure, and has become a reason for many of the environmental crisis like drought, soil maladies, ubiquitous pollution of water, threat to the existence of biotic species causing extinction of many species. Some of the indefinite unjustified activities penetrating into lake’s natural system and threatening its existence are:

• Flow of large quantities of nitrogen, phosphorus and organic matter that stimulate excess growth of algae and oxygen consuming bacteria. This process, known as cultural eutrophication, ultimately results in loss of water clarity, loss of oxygen in water affecting other organisms.
• Changes in physical landscape in the surroundings of the lake that affects the chemical inputs, which in turn affects the aquatic biota.
• Undesirable proliferation of exotic plant and animal species affecting native species and causing species loss in many lakes.
• Shrinkage of lake as a result of heavy silt landing, caused by soil erosion due to deforestation, overgrazing and other activities in the catchment area.
•  Over use, misuse and abuse of resources from the lakes affecting the ecological and biological integrity of the ecosystem

    Such anthropogenic pressure will severely affect the natural processes of the ecosystem, reduces its ability of self-organisation and the capacity of self-repair and all such external influences affects the overall health of the lake ecosystem. In the presence of undesirable and continuous external pressure, the ecosystem’s diversity, productivity, renewability and the entire integrity will be severely affected resulting into ecological degradation. Therefore ecological knowledge, and understanding about the various levels and functioning is necessary to skillfully use the ecosystem’s wealth without affecting the ecosystem’s health and sustainably maintaining them over time.

5. BIODIVERSITY AND THREAT

    The ability of a lake ecosystem to support and maintain a balanced, adaptive community of organisms having a species composition, diversity and functional organisation has made it a system with high biological integrity.The lakes of Mysore supports large number of flora and fauna. The biotic components mainly includes the phytoplankton, zooplankton, hydrophytes, periphyton, macro-invertebrates, fishes both endemic and exotic, birds which includes local and migratory birds, thus picturing a rich biodiversity. It is noteworthy to mention that these natural wealth from these lakes are intimately linked with the livelihood of the local inhabitants of this region.

5.1 Phytoplankton diversity

    The study of phytoplankton community, particularly the diversity, distribution pattern, abundance and variations along with the influencing factors forms an important part of lake-related studies. It is more important because the productivity of the lake ecosystem depends largely on the presence and diversity of the plankton biomass. Groups like Chlorococcales, Euglenophyceae, Cyanophyceae, Desmidaceae and Bacillariophyceae represent the phytoplankton community in the lakes. Mostly, the dominant phytoplankton group is the Bacillariophyceae and they were found to be dominant during summer. Generally the generic representation of Euglenophyceae is the lowest in the lakes. Cyanophyceae generally form blooms in the lakes, and these blooms of blue-green algae mainly included Anabaena oscillarioides. Microcystis aeruginosa. Phormidium fragile and Oscillatoria sps. The phytoplankton diversity and community structure can be best elucidated with the help of Soyer’s (1970) index (f%), which mentions about the frequency of their distribution, Bellan-Santini’s (1969) index (DI%) which gives details about the qualitative dominance of the species. Shannon-Weaver’s (1949) index (H') indicates the species diversity, Pielou’s (1975) index (J') indicates about the species evenness and Margalef’s (1952) index (SR) calculated gives details about the species richness in the lakes. Seasonal upsurge of some algal blooms has close relationship with the variations in certain parameters and also with anthropogenic perturbation. Many workers like Kumaraguru (1994), Hughes et al., (1958) have mentioned that cyanobacterial blooms are often capable of producing autotoxins which not only limit their own population, but also endangers the life of other aquatic organisms. Some of the dominant diatoms were Cymbella hungarica, Cyclotella catenata, Melosira islandica and Surirella capronoida.

5.2 Zooplankton diversity

    Zooplankton constitutes an important link in the aquatic food webs, transferring energy from the producers to aquatic carnivores. Ecologically, they form an important level of animals, which are also referred to as indicator species of pollution, fishery potentials and productivity of lake systems. Zooplankton are the ecological indicators of the waterbodies, and their distribution and abundance is an index for the health of an aquatic environment (Gajbhiye and Desai, 1981). They can be considered as the most suitable organisms for the toxicological studies and appropriate environmental monitoring of freshwater habitats, especially lakes, which is mainly due to their shorter life span and wide distribution. Based on their life cycle, it is possible to distinguish two major groups; the meroplankton, that spends only a part of their life cycle as plankton (temporary plankton) and the haloplankton, that are the permanent plankton. The zooplankton of lake waters are dominated by protozoans, rotifers, ostracods and the sub-classes of the crustaceae, the cladocerans and the copepods. During the study on the zooplankton diversity of the lakes of Mysore, more than 70 species belonging to 53 genera were identified. They showed the highest density during monsoon. Among the different groups, rotifers had the maximum representation. Certain species of rotifers, like rotaria, monostyla, lepadelly and cephalodella were indicator species of pollution. The cyclopoids has greater importance mainly because Microcyclops, Megacyclops and Mesocyclops attack mosquito larvae and helps in biological control. The cladocerans are also economically important because they are much preferred by the larvae of commercially important fishes. Chromadora candensis, Branchionus calciflorus and Keratella tropica are some of the dominant species found in lake waters.

5.3 Fish diversity

    The fish community in lakes includes the native species and the introduced species for the purpose of fish production. In Mysore district, there are many shallow lakes of varied dimensions, supporting rich ichthyofaunal diversity. The Cauvery river and its tributaries flowing through the district form many small and large reservoirs. There are more than 45 species of fishes identified from the lakes of Mysore. Many of the fish species are endemic to this region and the Cauvery river basin. Fishes belonging to genus Puntius, Labeo, Cirrhinus, Channa, Mystus are more common. Many species of genera Puntius like Puntius parrah, P. pinnauratus, P. narayani, P. puckelli reported by Jayaram et al., (1982) are not found commonly, indicating that they have become very rare. Exotic species introduced in most of the lakes either on purpose or accidentally can decimate native species and significantly alter the aquatic food webs. Oreochromis mossambica (Tilapia), which has inadvertently entered and dominated most of the lakes are prolific breeder and can multiply fast in them, thus resulting in the decline of indigenous fish species. Other exotic fish species commonly found are Hypophthalmicthys molitrix (Silver carp), Cyprinus carpio (Common carp) and Ctenopharyngodon idella (Grass carp), which are mainly stocked for fish production.

    The endangered fishes in the lakes were those, which were in danger of extinction and whose survival was unlikely if the causal factors continued to operate and happened to negatively influence them. Puntius filamentosus, Channa striatus and Labeo konitus were few endangered species. Threatened fish species were those fish species, which were likely to become endangered within the foreseeable future if the endangering factors are not checked. Danio aequipinnatus, Puntius carnaticus, Anguilla bengalensis were few threatened fish species identified from the lakes of Mysore. To conserve all endemic fish species and the total fish diversity, it is necessary to prevent drainage of pesticides and fertilisers from surrounding crop fields, heavy siltation during heavy rainfall, high density of fingerling stocking of selected culture fishes, fish diseases. Sustainable fish production by taking appropriate steps for sustaining fish diversity is necessary to conserve these vulnerable, but valuable resources.
Some rational management measures towards it are:

• In-situ conservation of endangered fish species
•  Prevention of over-stocking of fish fingerlings
•  Prevention of agro-chemical pollution and domestic pollution that can increase the nutrient levels causing eutrophication and connected problems.
•  Preventing Tiplapia-menace and proliferation of other exotic species, which can exert immense grazing pressure.
•  Ensuring that the water-use from them is within sustainable limits, to prevent habitat degradation.
•  Monitoring the waters to prevent the cynobacterial blooms which is known to produce toxins that can endanger the life of fish and other organisms.

5.4 Hydrophytes and others

    Macrophytes comprising of emergent, free-floating and submerged forms are remarkable plant life forming a more or less precarious footing in the lake ecosystem. Nymphaea, Nelumbo, Ceratophyllum, Vallisneria, Ipomea, Hydrilla, Eichhornia, Lemna, Trapa and Wolfia are the most common hydrophytes. Inhabitants staying close to the lakes use macrophytes as food, medicine, fibre, thatching and basketry.

    Large population of fish and gastropods get pocketed and exposed during winter, due to which a large number of migratory birds are attracted and thus are found to inhabit the banks of the lakes. The rhizomes of Nelumbo nucifera is powdered and prescribed for piles, similarly dried and powdered rhizome of Nymphaea nouchali is used for piles and dysentery. The cotyledons of Trapa, Nymphaea is edible and the stems of Phragmitis karka are used for making baskets and mats.

5.5 Threats to biodiversity

    The major threats to the biodiversity of lakes are;

•  Extension of agriculture in the vicinity of lakes and over-utilisation of water for irrigating the fields, causing decrease in the water levels, thus causing problems to the biotic components.
•  Filling up of many lakes and enroachment of lake area for urban extensions have resulted in habitat destruction, wiped out the biotic members.
•  Agro-chemical runoff, sometimes having toxic chemicals from surrounding fields causing danger to life of aquatic organisms.
•  Unscientific activities in the catchment area, causing excessive siltation, habitat destruction, thus posing threat to the life contained in it.
•  Flow of untreated sewage containing domestic wastes and discharge of polluted water has been another cause for reduction and elimination of population of sensitive species.
•  Uncontrolled commercial exploitation of species has endangered the species diversity, many becoming vulnerable and rare.
•  Introduction of non-native (exotic) species, especially for fish culture, has caused a decline of many endemic fish species, thus threatening the species richness.

To prevent these threats, proper conservation priorities have to be executed. Some steps towards it are:

? In-situ conservation of the critical species and the endangered species of organisms at the risk of extinction.
? Developing awareness about the endangered species and dangers of threatening biological integrity.
? Comprehending the vast social, economic, scientific, technological and ecological potentials of the biodiversity.

6. SUATAINABLE MANAGEMENT

    People should develop and adopt new, more ecologically sustainable and socially useful approaches that sustain ‘inter-generational equity’. The present and the future generation must strive to use resources and achieve comforts from the lake systems, that is equitably distributed and within the limits of the natural systems. To achieve any form of economic development with minimum damage to the lake structure, one needs to plan and implement those steps and procedures that are environmentally friendly, avoid any actions that happens to degrade it, and at the same time sustain its development. The quality of future life, especially of the future generation depends to a great extent on the present sustainable use and development of the resources from such aquatic systems. The past mistakes of over-consumerism and over-utilisation of resources from it, which are negatively experienced at present, should not penetrate into the future and threaten the well being and quality of life in the future. Sustainable development aims at utilisation of resources in a balanced and judicious manner. However several times, the utilisation of resources for development has caused several negative impacts. Therefore to make developments environmentally sound and sustainable without much constrains on the health of the lakes, the following aspects have to be considered:

6.1 Environmental Status Assessment (ESA)

    The status assessment of the existing environment in the vicinity of the lake, done scientifically will be an effective management strategy to prevent any adverse effects on the environment. Like cost-benefit analysis is done before the implementation of the developmental projects, similarly it is important to have a clear and systematic assessment of the present status of the lake. Status evaluation will enable in knowing whether the developmental projects can be implemented or whether the environment can support and sustain such proposals. The health of the environment in and around the lake when assessed will give the existing conditions and give details about its sustenance to the pressures of developmental projects.

6.2 Environmental Impact Evaluation (EIE)

    Lakes, which are important sources for drinking water, irrigation and life supporting systems for the biotic components can get degraded and deteriorated when influenced by severe anthropogenic activities. Pollutants of the lakes from various sources like domestic sewage, washing of herbicides, fertilisers disturbs lake ecosystem and increases the levels of nutrients, which gives rise to algal blooms and extensive growth of aquatic weeds. These growths impair and threaten the life of other organisms and also affect fish spawning, fishing, domestic use and even navigation. Environmental impact assessment is thus an objective analysis conducted to identify and measure the likely environmental, economic, social and aesthetic effects of any activity, which also helps in suggesting alternatives. Thus by this tool of management, the environmental quality is fully considered in decision making processes. The Environmental Impact Statement (EIS) obtained should cover the following:

• Effect on the lake system by the major activities in the catchment zone
• Impacts of deforestation and compensatory afforestation in the vicinity of the lake
• Impacts of domestic sewage, industrial effluents on the lake system
• Lake resource utilization and its impact on flora, fauna and total biodiversity.
• Enroachment of land on the banks of the lakes and its effects
• Effects of intensive agriculture in the vicinity and discharge of fertilisers into the lakes
• Environmental impacts of the less monitored and unscientific fish stocking and fish farming.

6.3 Environmental planning and administration

    Emphasis should be on prevention, rather than cure of environmental degradation. Environmental protection with economic development should become a more responsive need. Environmental impact statement, whose specific objective was to provide means for giving environmental quality, for which a careful and appropriate consideration in planning and administration should be one of the main objectives before all environmental decision making processes. Main basis for environmental planning and administration should be:

 •Approaches that aims at judicious use of resources, sustainable development and eco-friendly exercises.

• Proper resource utilisation and resource handling that enables in preservation and protection of lake environment

• Evaluating the impact of human activities on the lake systems, planning and designing strategies for sustainable development.

• Setting up institutions and centres for environmental management, which can actively co-ordinate with scientific efforts of applied groups that enables in implementing measures to have optimum balance in the total lake ecosystem.

• Environmental education that enables them to actively participate in the programmes that highlights the acts of protecting the lake and other ecosystems, the nature in whole, and expressing a concern towards preserving and conserving them.

7. AWARENESS ABOUT CONSERVATION

    It is a fact that uncontrolled dependence on the things from the lakes and connected resources, and the greed to flourish at all expenses of nature has created situations from which one can’t think of having a favourable, life enriching environment. Inspite of this extent of all happenings, all is not lost or over, and that forthcoming grim destiny can be held back by planning, implementing approaches that aims at judicious use of resources and most importantly by creating the awareness about its conservation. In the presence, and after surge of interest towards creating awareness about its conservation and working towards taking care of it, develop appreciation for its wonderful things and transform the interest into strong will to protect and conserve them. Habitat improvement programmes, mass awareness programmes have to be initiated on a regular basis to prevent all possible disasters in the future. Specially encouraging the learners to understand the environmental concerns in their own cognitive sphere and making better sense out of it will create and instill in them an awareness that will motivate them to secure them forever.

7.1 Role of individuals and community

    Individuals, groups, community should develop and reinforce in them an environmentally sensitive behaviour, understanding and avoiding those activities that disturbs the balance in the systems and develop a sense to find new patterns for sustainable utilisation of resources from these lakes. Sensitising oneself and the people around about the importance of lake systems and the problems, having genuine concern to its restoration and attempting to foster awareness about its complexities is necessary for sustainable development.

8. ENVIRONMENTALLY LITERATE LEARNERS

    Learners at the institutions should be provided with opportunities to acquire the knowledge, values, attitudes, commitment and skills essential to protect the lake and other aquatic ecosystems. They should think of a life in perfect harmony with the nature. They should also understand that all progress, in all forms, at any time should be in pace with sustainable development. The magnitude of importance lying in the application of sustainable development in harmony with the nature should be implanted into their mind, so that it grows and projects as efforts to protect the biodiversity, conserve the resources, thus emphasising sustainable development at a right time. Ultimately they should become self-motivated to care for nature and wisely use and live harmoniously with nature. Well-selected methods and techniques can only promote the objectives of creating awareness about the environmental sensitivity.

8.1 Education in the Environment

    Education in the environment involves the use of the environment as a resource for imparting education. If they are provided with opportunities to understand about the lake in a natural setting by taking them to visit the nearby lakes. Trying to establish at least few of the linkages in the concept of the textbooks by exploring the realities in a setting where they actually are able to experience them will make learning more practical and meaningful. Particular occurrence or presence of environmental issues or problems in the lakes closeby, resource utilization from them becomes more field-oriented, activity included methods which will bring about desirable changes in their behaviours that focuses on environmental issues. This will also enable in transferring the knowledge and skills in an intelligible and interesting manner, having some deepest influences on them.

8.2 Education about the Environment

    Education about the environment aims at understanding the environmental issues and problems. It mainly attempts at identification of the local environmental problems. Conducting surveys, investigating, and observation about the happenings in nearby habitats enables in the actual understanding of environmental issues connected with it. All innovative and creative methods of teaching like craft activities, story telling, performing plays, conducting exhibition are made use to familiarise issues of environment. Even the electronic media and internet facilities are best utilized to develop support materials and learning activities that gives the best experiences of environmental concepts. They should be enabled to develop the necessary skills of observing, collecting and studying the important components of the lake ecosystem. Education should enable them to develop a desire to have an in depth understanding of environmental issues and explore their contribution for the improvement and development of the degraded and threatened areas of the environment.

8.3 Education for the Environment

    Education for environment is actually a deeply felt approach that includes proper planning and developing learning activities that creates an awareness and understanding of the environment and develops an environment sensitive behaviour. Developing in the learners a concern, and instilling in them the values, attitudes, commitment and skills that ultimately involves in improving the environment. Methods like brain storming, case studies, field studies, project works, role-plays find much application as effective methods in fostering education for the environment. A teacher’s thoughtful ingenuity counts greatly in selecting the appropriate methods at appropriate situations or integrating them into the teaching concepts. The aims of imparting education regarding lake-related issues can be achieved if by proper teacher initiative, it is possible to develop a concern for the lake ecosystems, understand its important roles, develop a sense of responsibility to conserve them, and show an urgency towards everything that improves them. They should be motivated to participate in the programmes that highlight the acts of protecting the nature.

9. REFERENCES

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Hosmani, S.P and Naganandini M. N. 1998. Ecology of certain inland waters of Mysore district. Poll. Res.

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Jayaram, K.C. 1996. Manual for field identification – Common freshwater fishes of Karnataka. WWF Project , India .

Kumaraguru, A.K. 1995. Water pollution and Fisheries. Ecol. Env. Con . 1 (1-4) : 143-150 .

Miller R.L and Khan J.S 1962. Statistical analysis in the geological science. John Wiley and Sons . New York , USA .

Munnawar, M. 1970. Limnological studies on freshwater of certain polluted and unpolluted environment. Hydrobiologia, 39 : 105-128.

Pielou, E.E. 1975. Species diversity and pattern diversity in the study of ecological succession. J. Theor. Bio., 10 : 370-383.

Prescott , G.W. 1939. Some relationships of phytoplankton. Limnology and aquatic biology. Publ. American Asso. Adv. Sci . 10 : 65-78.

Shannon , C.E and Weaver, v. 1949. A mathematical theory of communication. Univ. Press, Urbana . 101-117 .

Trivedy, R.K and Goel, P.K. 1986. Chemical and biological methods for water pollution studies. Environmental Publication, Karad.

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