Restoration and enhancement of Hussain Sagar Lake Biodiversity 1 2 3 *S.M. Maqsood Javed , N. Chandramohan Reddy , C. Srinivasulu , 4 5 1 M.S. Kodarkar , C. Sudhakar Reddy and Farida Tampal *Corresponding author Email: Javedwwf2007@gmail.com 1 - WWF-India, Andhra Pradesh State Office, 818, Road No. 2, Castle Hills, Near NMDC, Vijayanagar Colony, Hyderabad -57 2 - Buddha Purnima Project Authority, # 6-3-1-2/1, Tank Bund Road, Hussain Sagar, Hyderabad Andhra Pradesh, India 3 - Department of Zoology, University College of Science, Osmania University, Hyderabad - 07 4 - Indian Association of Aquatic Biologists, VV College, Koti, Hyderabad - 95 5 - Forestry and Ecology Division, NRSA, Balanagar, Hyderabad -37 Abstract O O The 450 year old Hussain Sagar lake (17 25’22”N, 78 28’28”E) is one of the oldest man-made reservoir of peninsular India presently located in greater Hyderabad the capital city of Andhra Pradesh. For over four centuries it has been the main source of drinking water to the growing urban conglomerate of Hyderabad and its twin city – Secunderabad. The industrial expansion that commenced in early 1970’s in the catchment area of the Hussain Sagar Lake and continuous increment in terms of both industrialization and urbanization has polluted the Hussain Sagar Lake water to levels way above international permissible limits. This urban lake is choking to slow death and biodiversity both within the lake and environs has declined significantly. Keeping this in view, the WWF-India in collaboration with Buddha Purnima Project Authority of HUDA, Govt. of Andhra Pradesh has carried out biodiversity status study between February, 2007 and June, 2008 and suggests mitigation strategies to counter biodiversity loss. The study revealed decline in species diversity of all taxa in general and local extirpation of unique indigenous flora and fauna. Through this paper we would like to share the findings of the study and propose mitigation strategies to counter pollution levels and on-site remedial actions to restore and conserve biodiversity in general. To mitigate high concentration of heavy metals in water and sediments, and pollution in general we propose bioremediation strategies using microbial inoculation, phytoremediation and bioaugmentation. Cage culturing is recommended to increase fish diversity while installation of bat and bird boxes in surrounding environs is recommended for increasing bat and bird diversities. We also recommend landscape level intervention to increase the floral diversity which in turn would help in increase in species diversity of other biota. Introduction: The city of Hyderabad (centered 17.36ON and 78.47OE), is the capital of Andhra Pradesh. Founded by the Golconda rulers - the Qutub Shahi dynasty in 1590, the city was fabled to be the heaven on earth with beautifully planned layout strewn with palaces, kothis, mosques and living colonies for the common. The city of the yesteryears grew in expanse and by the late 20th century has established itself as an 1 important IT-hub. Hyderabad lies in the Deccan Plateau and rises to an average height of 540 m above the sea level. The futuristic and holistic approach of the city planners in the 16th century and later resulted in planning, commissioning and construction of a number of tanks and reservoirs, like Hussain Sagar, in and around Hyderabad to cater to the drinking needs of the citizens. Some of the lakes/reservoirs constructed then, like the Mir Alam, Osman Sagar and Himayat Sagar, are still the major sources of drinking water. Hussain Sagar Lake is one of the oldest man-made lakes/reservoirs of Andhra Pradesh. The salient features of this lake are provided in Table 1.1a. It is located in the middle of an urban expanse of the Hyderabad with Secunderabad lying to its north and most of Hyderabad to its south. This 450 years old lake is today well-known as one of the most polluted lake of the State (Kodarkar, 2001; Saravotham Rao, 2006) owing to urbanization pressures, industrialization and effluents discharge. The resultant effect has been the loss of aquatic and terrestrial biodiversity of the Lake and its catchment area. The present study was initiated between February 2007 and January 2008 by WWF-India on behalf of BPPA, to conduct a detailed study of the biodiversity and ecology of the Hussain Sagar Lake and to prepare an inventory of all existing flora and fauna along with the recommendation for its conservation. The major objectives of the present study include: 1. 2. 3. 4. 5. 6. Inventorying and recording seasonal changes of plants species present in and around the lake. Inventorying all the faunal species (terrestrial and aquatic) present in and around the lake. Monitoring and recording fluctuations, if any, in species presence. Inventorying microbial fauna like- algae, fungi and planktonic organisms found in the lake. Mapping important habitats for plant and animal activity in and around the lake. Recommending suggestions for improvement of the biodiversity. Study Area: The Hussain Sagar Lake and its environs were surveyed and different sampling sites were established for maintaining consistency in sampling. Terrestrial flora and fauna: The entire shoreline and adjacent areas were surveyed for studying terrestrial flora and fauna, four sampling sites (Fig. 1) were selected, namely, A. B. C. D. Sanjeevaiah Park and Wetland eco-conservation zone (WECZ) Sailing Club Lumbini Park, and NTR Gardens, were selected. Aquatic flora and fauna: For studying the aquatic flora and fauna, water samples from the lake as well as the feeder canals were collected at regular intervals during the study period. To maintain consistency in the sampling procedures, four sampling sites (Fig. 1), were selected. Brief details of these sampling points are provided below: 1. STP point (GPS: 170 24’ 59’’N & 780 28’ 06’’E): This point is situated at the entrance of the inlet that brings in treated water from the existing 20 MLD Sewage Treatment Plant. The treated 2 water is expected to bring about an improvement in the water quality in the lake. The point is selected to monitor if there is any change in phyto- and zooplankton in this zone of the lake. 2. Kukatpally point (GPS: 170 25’ 58’’N & 780 28’ 12’’E): The sampling station is at the zone where a mix of effluents and sewage from the Kukatpally stream enters the lake. This zone is extremely polluted and has heavy silt and effluent residues. 3. Picket point (GPS: 170 25’ 49’’N & 780 28’ 54’’E): This sampling station is situated at the mouth of the Picket nala that comes from Begumpet. It is the area where a new STP of 50 MLD capacity is proposed. 4. Central Lake Point (GPS: 170 25’ 01’’N & 780 21’ 37’’E): This sampling site is near the Buddha Statue, where the lake is the deepest. 3 Fig. 1. Hussain Sagar Lake – Showing study and sampling sites Courtesy: Google earth 1-4 A-D Site A: Sanjeevaiah Park = Planktonic biota sampling sites = Terrestrial biota sampling sites Site B: Sailing Club Site C: Lumbini Park Site D: NTR Gardens 4 Methodology: Aquatic flora and fauna Planktonic Sampling – Collected water samples were analyzed in the laboratory of the Indian Association of Aquatic Biologists (IAAB), Hyderabad and Environmental Biology Lab, Kakatiya University, Warangal. Standard identification protocols were followed (Needham and Needham, 1972, APHA, 1991, Kodarkar, 2006). Terrestrial flora and fauna At these sampling sites flora and fauna encountered were documented on a monthly basis. These sites were visited between 0600 to 1100 hrs and 1600 to 1830 hrs for 7-days during the first week of every month between February 2007 and January 2008. For detection of nocturnal fauna a total of six night surveys between 2000 to 2359 hrs were also conducted. • Floral Sampling – All floral elements that were encountered were photographed and a herbarium of the seasonal wild herbs collected has been prepared. Two sites, namely the WECZ near Jalvihar and Sanjeevaiah Park, were studied intensely as on these two sites, more number of species occurred naturally. The species were identified using standard guides (Pullaiah and Chennaiah, 1997). • Faunal Sampling – All faunal elements that were encountered were photographed. Bird diversity was studied through observation on nesting and roosting sites). Identification of species followed Ali & Ripley (1987). Herpetofauna (reptiles and amphibians) were studied by direct observation and encounter rates. Das (2002) and Daniel (2002) were followed for the identification of herpetofauna. Mammals were detected by direct sighting methodology. Invertebrates were estimated using percent frequency of occurrence and were identified following Kodarkar (2006). Status of different groups recorded during the study is as given below: An exhaustive biodiversity inventory of Hussain Sagar Lake has never been attempted till date. The present study has tried to achieve this. The lake supports several species of microorganisms, migratory and resident birds, freshwater fishes, reptiles, amphibians and other aquatic creatures, and several species of aquatic and terrestrial flora. The study revealed the existing status of the biodiversity and ecology of the Hussain Sagar Lake. Among the microorganisms about 3 species of phytoplanktons and 30 species of zooplanktons were recorded. In flora about 117 plant species (103 wild and 14 planted) belonging to 40 families were recorded. In fauna a total number of 48 species of butterflies, 7 species of dragonflies, 2 species of damselflies, 2 species of amphibians, 7 species of reptiles, 4 species of fishes, 77 species of birds and 6 species of mammals were recorded from the Hussain Sagar Lake and its environs. Noteworthy findings include a wild herb Euphorbia sebastinei (Fig.2) and a rare bird Grey-headed Lapwing Vanellus cinereus (Fig.3). 5 This study endeavors to address certain lacunae in knowledge by gathering comprehensive information on the biodiversity and ecology of the Hussain Sagar Lake and its environs. We are hopefully that the mitigation strategies and recommendations mentioned in this article would be useful for biodiversity management, conservation and research in a long run. Javed/WWF-APSO Fig. 2. Euphorbia sebastinei Javed/WWF-APSO Fig. 3. The Grey-headed Lapwing Vanellus cinereus Mitigation Strategies and Recommendations: As is evident by the present study, certain biodiversity components of the Hussain Sagar Lake ecosystem are alarmingly low leading to a visible misbalance. This could be attributed to the rapid anthropogenic changes around Hussain Sagar Lake. To restore the ecological balance of the lake, the following mitigation measures are recommended. A. Maintaining high water quality : The present practice of controlling on site pollution levels of the industrial effluents and water treatment by sewage treatment plants is commendable. But it does not cater for all the inlets of the lake such as Kukatpally and Picket nalas. Certain cost effective treatment procedures has to be used such as bioremediation, phytoremediation and bioaugmentation (or biostimulation) are recommended. Bioremediation - Bioremediation can be defined as a process that uses microorganisms or their enzymes to return the environment altered by contaminants to its original condition. Bioremediation may be employed to attack specific contaminants, such as chlorinated pesticides that are degraded by bacteria, or a more general approach may be taken, such as oil spills that are broken down using multiple techniques including the addition of fertilizer to facilitate the decomposition of crude oil by bacteria. However, it is important to note that not all contaminants 6 are readily treated through the use of bioremediation; For example, heavy metals such as cadmium and lead are not readily absorbed or captured by organisms. The integration of metals such as mercury into the food chain may make things worse as organisms bioaccumulate these metals. Generally, bioremediation technologies are classified as in situ or ex situ. In situ bioremediation involves treating the contaminated material at the site while ex situ involves the removal of the contaminated material to be treated elsewhere. Phytoremediation - Phytoremediation is the direct use of living plants for in situ remediation of contaminated soil, sludge, sediments, and ground water through contaminant removal, degradation, or containment. Growing and, in some cases, harvesting plants on a contaminated site as a remediation method is an aesthetically pleasing, solar-energy driven, passive technique that can be used to clean up sites with shallow, low to moderate levels of contamination. This technique can be used along with or, in some cases, in place of mechanical cleanup methods. Phytoremediation can be used to clean up metals, pesticides, solvents, explosives, crude oil, polycyclic aromatic hydrocarbons, and landfill leachates. Phytoremediation is a general term for several ways in which plants are used to remediate sites by removing pollutants from soil and water. Plants can degrade organic pollutants or contain and stabilize metal contaminants by acting as filters or traps. Some of the methods that are being tested are described below (US-EPA, 1999). Phytoextraction, also called phytoaccumulation, refers to the uptake and translocation of metal contaminants in the soil by plant roots into the aboveground portions of the plants. Certain plants like hyper accumulators absorb unusually large amounts of metals in comparison to other plants. One or a combination of these plants is selected and planted at a site based on the type of metals present and other site conditions. After the plants have been allowed to grow for several weeks or months, they are harvested and either incinerated or composted to recycle the metals. This procedure may be repeated as necessary to bring soil contaminant levels down to allowable limits. If plants are incinerated, the ash must be disposed of in a hazardous waste landfill, but the volume of ash should be less than 10% of the volume that would be created if the contaminated soil itself were dug up for treatment. Example: Indian mustard (Brassica juncea). Rhizofiltration is the adsorption or precipitation into plant roots or absorption into the roots of contaminants that are in solution surrounding the root zone. The plants to be used for cleanup are raised in greenhouses with their roots in water rather than in soil. To acclimatize plants once a large root system has been developed, contaminated water is collected from a waste site and brought to the plants where it is substituted for their water source. The plants are then planted in the contaminated area where the roots take up the water and the contaminants along with it. As the roots become saturated with contaminants, they are harvested and either incinerated or composted to recycle the contaminants. Ideal plant for rhizofiltration should be able to accumulate and tolerate significant amounts of the target metals in conjunction with easy handling, low maintenance cost, and a minimum of secondary waste requiring disposal. It is also desirable plants to produce significant amounts of root biomass or root surface area (Prasad and Freitas, 2003). Example: Water hyacinth (Eichhornia crassipes); Pennywort (Hydrocotyle umbellate) and Duckweed (Lemna minor). 7 Phytostabilization is the use of certain plant species to immobilize contaminants in the soil and ground water through absorption and accumulation by roots, adsorption onto roots, or precipitation within the root zone. This process reduces the mobility of the contaminant and prevents migration to the ground water or air, and it reduces bioavailability for entry into the food chain. This technique can be used to reestablish a vegetative cover at sites where natural vegetation is lacking due to high metal concentrations in surface soils or physical disturbances to superficial materials. Metal-tolerant species can be used to restore vegetation to the sites, thereby decreasing the potential migration of contamination through wind erosion, transport of exposed surface soils, and leaching of soil contamination to ground water. Plants chosen for phytostabilization should be poor translocators of metal contaminants to aboveground plant tissues that could be consumed by humans or animals. The lack of appreciable metals in shoot tissue also eliminates the necessity of treating harvested shoot residue as hazardous waste. Example: Agrostis tenuis and Festuca rubra (cultivars). Phytodegradation, also called phytotransformation, is the breakdown of contaminants taken up by plants through metabolic processes within the plant, or the breakdown of contaminants external to the plant through the effect of compounds (such as enzymes) produced by the plants. Pollutants are degraded, incorporated into the plant tissues, and used as nutrients. Rhizodegradation, also called enhanced rhizosphere biodegradation, phytostimulation, or plant assisted bioremediation/degradation, is the breakdown of contaminants in the soil through microbial activity that is enhanced by the presence of the rhizosphere and is a much slower process than phytodegradation. Microorganisms (yeast, fungi, or bacteria) consume and digest organic substances for nutrition and energy. Certain microorganisms can digest organic substances such as fuels or solvents that are hazardous to humans and break them down into harmless products through biodegradation. Natural substances released by the plant roots— sugars, alcohols, and acids—contain organic carbon that provides food for soil microorganisms, and the additional nutrients enhance their activity. Biodegradation is also aided by the way plants loosen the soil and transport water to the area. Phytovolatilization is the uptake and transpiration of a contaminant by a plant, with release of the contaminant or a modified form of the contaminant to the atmosphere from the plant. Phytovolatilization occurs as growing trees and other plants take up water and the organic contaminants. Some of these contaminants can pass through the plants to the leaves and volatilize into the atmosphere at comparatively low concentrations. Example: Cattail (Typha latifolia) and Arabidopsis thaliana. Bioaugmentation - Bioaugmentation can be defined as the addition of pre-grown microbial cultures to enhance microbial populations at a site to improve contaminant clean up and reduce clean up time and cost. As biodegradation is the major process affecting natural attenuation of contaminants, and during this process, contaminants are metabolized into less toxic or non-toxic compounds by naturally occurring organisms. As often these natural processes are slow and there is a requirement to increase the rate of biodegradation. This can be accomplished by one of two main techniques: bioaugmentation and biostimulation. Biostimulation is the technique of adding amendments to the soil or groundwater matrix to stimulate the native microbial population to increase in size, which could be another term for ‘enhanced bioremediation’. 8 Thus, bioaugmentation is the addition of native or non-native microbial cultures or “inocula” to the matrix to enhance or replace the native microbial population. Indigenous or native microbes are those that occur naturally at a site. They are usually present in very small quantities. They may not be able to prevent the spread of the contaminant. In some cases, native microbes do not have the ability to degrade a particular contaminant. Bioaugmentation offers a way to provide specific microbes in sufficient numbers to complete the biodegradation. Microbial inocula are prepared in the laboratory from soil or groundwater either from the site where they are to be used or from another site where the biodegradation of the chemicals of interest is known to be occurring. Microbes from the soil or groundwater are isolated and are added to media containing the chemicals to be degraded. Only microbes capable of metabolizing the chemicals will grow on the media. This process isolates the microbial population of interest, which may contain several different strains of microbes. The isolated microbes can then be propagated in a nutrient medium and concentrated to produce an inoculum. Using native soils has the advantage that the microbes are more likely to survive and propagate when reinjected at the site, and also there will be less public resistance to their use. Using microbes from a different site has the advantage that they are known to biodegrade the chemicals of concern. However, there is a possibility that these microbes will not be able to adapt to their new environment and will not propagate. Typically the microbes will adapt if the new environment is similar to their native environment. There are simple laboratory tests that can be performed before inoculum injection to ensure the biocompatability and biodegradation efficiency of the microbes. Bioaugmentation has several advantages over biostimulation. A concentrated population of specific microbes is injected and can begin degrading contaminants immediately. For biostimulation there is a delay after injection of nutrients as the microbial population propagates. Also, the nutrients are not specific and all microbes present at the site will potentially propagate, diluting the effect of the nutrients. One of the main environmental applications for bioaugmentation is at sites with chlorinated solvents. Reductive dechlorination of solvents such as perchloroethylene and trichloroethylene is performed by microbes called Dehalococcoides ethenogenes. These microbes may not be present at a chlorinated solvent site or the microbes present may not completely reduce the chloroethenes to ethene and ethane. Injection of an inoculum from a site where the solvents are being completely degraded can quickly activate the pathway at the site, thereby reducing cleanup costs and time. Inocula are also available for treating BTEX (benzene, toluene, ethylbenzene, and xylene) contaminated sites. Research programme and funding should be channelized in this direction to prepare site- and compound-specific inocula that are present in Hussain Sagar Lake. Bioaugmentation has many applications in municipal wastewater treatment. These include: • • • • • Accelerating system start-ups to achieve steady-state operation in days as opposed to weeks; Enhancing removal of pass-through or difficult-to degrade compounds (surfactants, solvents, oil and grease, petroleum hydrocarbons, etc.); Improving biological oxygen demand (BOD) and Total Suspended Solids (TSS) removal efficiency; Reducing sludge through increased enzymatic activity on biodegradable solids; Reducing foam due to degradation of surfactants and de-stabilization of filamentous bacteria; 9 • • Reducing odor due to greater degradation of odor causing compounds (H2S, mercaptans, amines, volatile fatty acids, etc.); and Improving solids settling by destabilizing filamentous organisms. Other applications include improving nitrification (ammonia removal), polymer reduction and greater oxygen transfer efficiency. Bioaugmentation can also be a less costly alternative to retrofitting a plant in some cases. Additionally, bioaugmentation can be used for treatment of oil and grease in the automotive and petroleum industries, grease in the food industry, septic tanks, and wastewater treatment in the chemical industry. In Catchment Area As there are many numerous polluting industries and human habitations in the catchment of the Hussain Sagar Lake, the mitigation measures need to be holistic in approach and should address problems at multi-level and multi-dimensional aspects. The effluents that join the main canals of the Hussain Sagar Lake should be properly treated by individual industries or consortium of industries before it is dumped in to the feeder canals. Same is the case with sewer lines. Establishment of Sewage Treatment Plants on all the main canals is greatly needed. Besides these, different technologies available to contain heavy metal and oil-based contaminants are to be implemented. We propose that all industrial effluents and waste water needs to be treated by bioaugmentation process using different commercially available ‘inocula’. In the low lying areas, especially the backwaters of the Hussain Sagar Lake, phytoremediation using two of the abundant exotic weeds, namely, Water Hyacinth Eichhornia crassipes known for accumulation of heavy metals such as lead (Pb),chromium (Cr), zinc (Zn), manganese (Mn), and copper (Cu) (Tiwari et al., 2007), Amaranthus spinosus and Alligator Weed Alternanthera philoxeroides, needs to be undertaken. In Lake Basin In the lake basin and at all the mouths of the main and feeder canals, ‘floats’ of Water Hyacinth Eichhornia crassipes and reedbeds of Typha angustata, Cyperus spp. of different sizes and shapes need to be maintained to achieve phytoremediation. Similarly on the shorelines maintaining beds of Alligator Weed Alternanthera philoxeroides would serve the purpose. These two weeds are known to have high uptake of heavy metals. Different protocols and different regimens of treatments need to be implemented to treat the Lake water. Although complete draining has been suggested before such an action is implemented, we do not recommend this process as it might lead to shifting of the problem to other areas rather than mitigating it. As such there are only few biotas existing in the waters of Hussain Sagar Lake, large scale water treatment, either directed to coagulate contaminants and heavy metals and / or bioaugmentation using different ‘inocula’, would serve the purpose. Once the levels of heavy metals and other pollutants are brought under permissible levels, vegetation and other biota can be reintroduced into the system. Such processes have been successfully implemented in some of the lakes in Canada and Europe. The holistic approach that was followed to treat and contain pollution levels in Thames River in United Kingdom is the best example that gives us the hope that the water quality of Husain Sagar Lake could be brought back to normal levels. 10 B. Biodiversity Conservation: The environs of Hussain Sagar Lake have visibly shrunk over the years with the development of human establishments. These factors have definitely affected the lakes biodiversity. On the other hand, the establishment of parks, roadside plantation and the wetland eco-conservation zone has conserved green cover to some extent. This in turn has attracted a rich variety of garden birds, but it is not so. When compared to Indira Park, the numbers of individuals of garden bird species is relatively low in Sanjeevaiah Park and NTR Gardens. This is attributed to human disturbance and also to non-availability of food plants and roosting or nesting sites. Similarly, biodiversity in the water, especially the planktons and fish has drastically declined. Only hardy species that can tolerate high levels of contaminants survive here. To augment biodiversity and the populations of already existing species reintroductions of micro-organisms, cage culture of some fish species, plantation of butterfly host plants and installation of bird nest- and bat-boxes are suggested. The details of the strategies that need to be implemented are provided below. In Lake Basin The aquatic biodiversity in the Hussain Sagar Lake could be increased only after the increased BOD/COD level in water is brought under normal levels. To increase the diversity and populations of micro-organisms, meso-organisms and planktons, inoculation of the Lake is suggested. This can be attained by bringing water and sediment samples from other lakes and water bodies and ‘injecting’ the material in to the Husain Sagar Lake for this experiment to be successful, it must be ensured that Hussain Sagar water is free of toxic heavy metals. Constant sequel monitoring would be needed for this. Repeated efforts by the state fisheries department to feed the lake with carp and other fish fingerlings have been unsuccessful. It is possible that the lake water is not conducive to the survival of certain fish. Only the hardy and voracious Clarius batrachus survives. Fish species diversity could be augmented by following Cage Culture practice. The details of this practice that could be implemented in Husain Sagar Lake are provided below. Cage culture - Cage culture can be practiced in standing bodies of water such as ponds, lakes, reservoirs, rivers, and streams (Huguenin, 1997). Cage culture is an inexpensive method to augment fish populations under supervision. By this practice the fish health and growth are easier to monitor in conjunction with physico-chemical parameters (Temperature, Oxygen, pH, Alkalinity and hardness, and levels of Ammonia) of the water. Cages have developed a great deal since their inception and today there is a diversity of types and designs. Fish cages used could be one of the following four types: a) Fixed - Fixed cages consist of a net supported by posts driven into the bottom of a lake or river; they are comparatively inexpensive and simple to build, but their use is restricted to sheltered shallow sites with suitable substrates. b) Floating - The floating cages have a buoyant frame or collar that support the bag; they are less limited than most other types of cages in terms of site requirements and can be made in a great variety of designs, and are the most widely used ones. 11 c) Submersible - The submersible cages rely on a frame or rigging to maintain shape. The advantage over other designs is that its position in the water column can be changed to take advantage of prevailing environmental conditions. Generally these cages are kept at the surface during calm weather and submerged during adverse weather. d) Submerged - The submerged cages can be wooden boxes with gaps between the slats to facilitate water flow and are anchored to the substrate by stones or posts. The fish cages can be built in several types and sizes; however most of them present the following common components: floating system, mooring system, anchor system, net cage and services system. Floating system: Provides buoyancy and holds the system at a suitable level in the surface of the water. In some cages this component is an important part to hold the shape of the cage. Common flotation materials include metal or plastic drums, high-density polyethylene (HDPE) pipes, rubber tires and metal drums coated with tar or fiberglass. Fiberglass drums or buoys are preferred as they can last for many years although the initial cost is comparatively high. Styrofoam blocks, covered with polyethylene sheets provide good buoyancy and may last for as long as 5 years under tropical conditions (Chua and Tech 2002). The buoyant force varies depending on size and materials used. The assembly of the system can be by connectors, stitching or tying. Services system: This is the system required for providing operating and maintenance services, for example: feeding, cleaning, monitoring or grading. One way to provide this is by a catwalk around the cage or along part of the cage. Some cages use their flotation collars like catwalks and access for these services. These flotation collars are made of metal or plastic pipes with or without additional internal or external floats. The assembly with the cage or its structure is by connectors or ties using ropes. The size depends on the cage design. The initial cost of catwalks could be relatively high, but the services are indispensable. Alternative methods to provide these services are by access from a boat or a more stable platform such as a barge or a raft. Cage bag: The function of the bag is to contain and protect the fish and to provide a marine habitat. The net is normally flexible and made of synthetic netting of nylon or polythene fibers reinforced with polythene ropes, although recently new stronger materials like Spectra or Dynema have appeared. The nets are kept stretched vertically with weights at the bottom of the cage or fastened by rope to the framework depending of the type of cages (Chua and Tech, 2002). Rigid cages made of metal netting (galvanized mesh, copper-nickel mesh or vinyl-coated mesh) mounted on rigid metal frameworks also are used. The flexible net bag is most used due to cost (Huguenin, 1997). Mooring system: This holds the cage in the suitable position according to the direction and depth decided in the design, and sometimes helps to maintain the shape of the cage. The mooring joins the cage at the anchor system. A mooring system must be powerful enough to resist the worst possible combination of the forces of currents, wind and waves without moving or breaking up (Thoms, 1989). The materials used in the mooring systems are sea steel lines, chains, reinforced plastic ropes and mechanical connectors. The mooring force capacity depends on both the material and size, and can be adjusted to the requirements. Attachment to the system is by metallic connectors and ties. 12 Anchor system: This holds the cage and all the components in a particular site in the seabed and is connected to the cage by the mooring system. There are basically three types: pile anchors, dead weight anchors and anchors that get their strength by engaging with the seabed. Pile anchors are buried piles in the seabed, they are effective, especially for systems where a small space is necessary, they are driven into the seabed usually by a pile hammer from a barge on the surface; but, they are expensive to buy and install. Dead weight anchors are usually concrete blocks. Their one big advantage is that they are fairly consistent in holding power (Thoms, 1989). There are a few basic principles to consider when building a fish cage: 1. All material used for the cage should be durable, nontoxic, and rustproof. Copper and zinc can be toxic. Galvanized wire has been used in the past, but it usually rusts-out after one year and fish may injure themselves on the rough surface. Plastic netting or vinyl coated wire fabric is often used. Sunlight can also damage the plastic mesh, so leaving the cages in the water year-round may be better than pulling them out and storing on the pond bank. 2. The netting material used for the body of the cage must allow maximum water circulation through the cage without permitting fish escapes. Mesh sizes less than 1⁄2 inch oRen clog with algae. Netting material of 1⁄2 inch and 3⁄4 inch mesh size are most commonly used. 3. Some type of flotation is needed to suspend the cage at the water’s surface - small inner tubes, plastic jugs, or pieces of styrofoam. Clear plastic jugs do not last as long as colored ones. PVC cement should be applied to the cap threads to prevent water leakage into the jugs. 4. Sunlight stresses fish; therefore a lid should be included to block some of the light. Lids also prevent predators from entering the cage and fish from jumping out. The lid should incorporate a feeding hole for free access. Cage fabric lids covered with fiberglass (filon) lids are suggested. 5. Fish cages should have a volume of at least 1.3 cubic yards or 35.7 cubic feet (1.0 m3). Cylindrical shaped cages appear to work the best; however, square or rectangular shaped cages are widely used. The cylinder has no corners for the fish to bump into and become injured. Regardless of the shape, do not lift the entire cage out of the water with the fish inside unless the cage is properly reinforced. 6. Fish cage placement - It is very important that the wastes from the fish and excess fish feed fall through the cage and away from the immediate area of the cage. Therefore, the fish cage should be placed in an area where there is at least two feet of water between the bottom of the cage and Lake Bottom. It is undesirable for wastes to accumulate near the fish cage. Cage should be placed in open water where the prevailing winds can create water movement. Even the slightest breeze helps to flush water through and around the cage, remove waste products, and provide fresh, oxygenated water. Disturbances near the cage, such as swimming, boating, and fishing activities are not desirable. Lake Environs The lake environs itself need to be given special attention. Open spaces surrounding the lake should be vegetated with butterfly host plants and species that attract birds and bats (Appendix IV). 13 Indigenous elements should be given preference. However, the lake being in the midst of the city and perceived by common man as a ‘tourist spot’, ornamental species would also suffice. We suggest the following strategies to achieve the same. Habitat modification – Open spaces and wetland eco-conservation zone need to be covered with plants that simulate the riparian habitats. A landscape of vegetation gradient beginning with emerging vegetation on the lake bed, followed by a belt of aquatic grasses (like Typha angustata, Cyperus spp., etc.), followed by a belt of butterfly host herbs and shrubs, lastly followed by indigenous trees need to be created. This landscape should be kept out-of-bound from human interference allowing it to regain its biodiversity. Bird Nest- and Bat-Boxes - To increase the bird and bat populations in the vicinity of Hussain Sagar Lake, putting up bird nest boxes and bat boxes is recommended. 1. Bird Nest Box – These are made up of wood, and may be of different sizes and shapes. These boxes provide nesting sites for many species of urban dwelling birds. Provision of nest boxes in urban parks has been beneficial in terms of bird diversity. 2. Bat Box – Bat boxes are made up of wood, and may be of different sizes and shapes. These boxes provide roosting sites to many insectivorous species of bats. Provisions of bat boxes in urban parks are known to increase bat diversity. Resource protection – Large portions of the 200m wide lakeshore of Hussain Sagar Lake are under severe disturbance caused by tourism activities. Some of the tracts that are not yet been developed need to be conserved as “Conservation Belts” where no human disturbance is allowed. The immediate lakefront area facing such zones should also be protected from any kind of disturbances. This measure would ensure the natural process of faunal colonization once re-vegetation has been initiated. C. Outreach Programmes During the study it was found that the local stakeholders as well as most of the tourists who visit Hussain Sagar Lake are unaware of the essential needs of the environment and biodiversity. Except complaining about the deteriorating water quality as suggested by the disquieting stench, a large percentage of populace is ignorant of the status of Hussain Sagar Lake and its biodiversity. For increasing awareness about the same, we recommend the following: 1. Educational Hoardings – Although there are a few such hoardings in place, we suggest more colorful interesting and informative hoardings to attract people’s attention. 2. Posters depicting Flora and Fauna – Posters depicting flora and fauna of Hussain Sagar Lake needs to be prepared and distributed to schools, colleges Government offices, tourist spots, eateries, entertainment parks, boating and sailing clubs around the lake. 3. Posters and pamphlets depicting destructiveness of untreated effluents on lake and its biodiversity – Using data recorded during the present study, posters and pamphlets depicting effects of untreated effluents on Hussain Sagar Lake and its biodiversity needs to be prepared. These documents should emphasize on the responsibility of each visitor to ensure the cleanliness of the lake directly and indirectly. 14 4. Website – An official website on Hussain Sagar Lake and its biodiversity would go a long way in making tech savvy public aware about the status and conservation actions taken. Websites already existing on the tourism aspects of the lake may be furnished with additional information on biodiversity of the lake and BPPA’s efforts at conservation. These are expected to motivate visitors browsing website to change their outlook. 5. An Annual Lake Festival – An Annual Hussain Sagar Lake Festival should be conducted, involving school and college students and other citizens to drive in the information on Hussain Sagar Lake and its biodiversity status. This would also help in garnering public support to take action against any industry or enterprises that is observed to be polluting the lake in the catchment area. 6. Nature Interpretation Centre – A Nature Interpretation Centre near Hussain Sagar Lake is recommended to educate visitors, school and college students about the importance of the Hussain Sagar Lake, biodiversity and conservation. Conclusion: The study summarizes and outlines recommendations to mitigate the environmental constraints that degrade biodiversity. As the Hussain Sagar Lake’s catchment area is heavily urbanized, it is felt that the efforts to improve water quality and restore ecological balance would have valuable results with global implications. A holistic approach of ecosystem restoration and management through the above given mitigation strategies would be the ideal way to conserve Hussain Sagar Lake and its environs. Acknowledgements: Ms. Farida Tampal (FT) and Mr. S. M. Maqsood Javed (SMMJ) acknowledge Mr. Jayesh Ranjan, IAS, former VC, HUDA; Mr. K.S. Jawahar Reddy, IAS, VC, HUDA and BPPA authorities for their keen interest in knowing the status of biodiversity of the Lake and sanctioning the project. We acknowledge Mr. Anil Kumar V. Epur, Chairman of WWF Andhra Pradesh State Committee and all State Committee Members for being a great source of inspiration for all our efforts. FT and SMMJ also thank Mr. Ravi Singh, SG and CEO of WWF-India for his continued support and encouragement. Dr. C. Srinivasulu and Dr. C. Sudhakar Reddy acknowledge the Department of Zoology, Osmania University and NRSA respectively, for lending facilities and support during the studies. Dr. Chiranjibi Pattanaik is also acknowledged for painstakingly preparing the herbarium and Dr Ravishanker Piska for his identification of the fish species. All the authors are thankful to the following individual’s Mr. G. Anand, Mr. P.S.M. Srinivas, Ms. Archana Waran, Mr. S. Saravanan and Mr. Venkat for providing logistical and administrative support. We also acknowledge Mr. Sreekar (WWF Volunteers) and Ms. Sneha Mala Kesiraju (WWF intern) for help during surveys and secondary data collection. Thanks to Mr. Sreekar and Mr. Rudra Pratap for keeping an eye on the bird activity at the lake and for sighting Grey headed Lapwing. References: Chua, T.E. and E. Tech (2002). Introduction and History of Cage Culture. CAB International, 40pp. Daniel, J.C. (2002). The Book of Indian Reptiles and Amphibians. BNHS-Oxford University Press, Mumbai. viii + 238pp. 15 Das I. (2002). A Photographic Guide to the Snakes and Other Reptiles of India. New Holland publishers (U.K.) Ltd., London. 144 pp. Huguenin, J. (1997). The design, operations and economics of cage culture systems. Aquacultural Engineering, 16: 167-203. Kodarkar, M.S. (ed.) (2006). Methodology for Water Analysis. Publ. No. 2, 3rd Edition. IAAB, Hyderabad. 106 pp. Prasad, M. N. V. and Freitas, H. M. D. O. (2003). 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