The algal bloom at the Ulhitiyawa Reservoir
March 19, 2013, 8:20 pm (Island News Paper)
by Vidya Nidhi PROF. S. A. Kulasooriya
The Ulhitiyawa reservoir is situated between Mahiyangana and Dehiattakandiya in the Badulla District of the Uva Province. People interviewed on television said that they have observed several wild animals including water birds and elephants avoiding the reservoir water which indicated that it is not safe to use the water. It is heartening to find that our rural population is aware of such dangers. A public health Inspector on TV stated that samples have been sent to the Medical Research Institute (MRI) and they were awaiting advice from the authorities.
Major source of water
Ulhitiyawa tank is the major source of water for a number of families living in this area. The plight of the people who were not sure whether it is safe to use this water or not, has yet to be known. The Institute of Fundamental Studies Kandy (IFS) has the expertise and facilities to investigate this type of problem. We therefore took the initiative to send a team to bring some representative samples of the bloom and water from the affected areas of the reservoir.
Microscopic examination of the algal samples revealed that the bloom is due to the predominant presence of Microcystis aeroginosa. The irregularly shaped loose colonies of several cells each having numerous gas vesicles which make them buoyant are typical characteristics that make it easy to identify this blue-green alga. These algae are now categorized as Cyanobacteria because of their prokaryotic cellular structure. However in common parlance and in limnology they are still commonly called algae.
This cyanobacterial species is well known to produce a group of toxins called microcystins that are toxic to digastrics animals. It is a hepato-toxin that affects the liver of humans. The presence of algae is normal in stagnant water bodies but bloom formation is generally associated with the increase in nutrient content called eutrophication often supported by high light and high temperature. Nutrients that frequently spark off algal blooms are phosphorous and nitrogen and these are generally associated with pollution particularly from the unrestricted use of fertilizers and other agro-chemicals as well as soap and washing powders.
An interesting observation during our microscopic examination of the algal samples was that the Microcystis colonies were invariably associated with short Nostocacean filaments some of which had heterocysts, the specialized cells that fix atmospheric nitrogen (see the photograph).
This means that this association could grow rapidly even under low levels of nitrogen and the critical nutrient for bloom formation in this case is likely to be phosphorous. This proved to be correct as determination of available phosphorus in our laboratories as well as those reported by others including the National Water Supply and Drainage Board, reported high levels of available P in these waters.
We also determined the levels of the algal toxin Microcystin as well as the presence of DNA capable of producing this toxin in the samples collected. The levels of Microcystin were 2.5 micro-grams per liter which was very high and more than twice the level of one micro-gram per liter given by the WHO as the upper dangerous limit. The potential toxin producing DNA levels were also very high. (We are in the possession of verifiable results that could be scrutinized by any organization).
Toxins in 61 inland
reservoirs
Recent surveys carried out by the IFS in 61 inland reservoirs of Sri Lanka has shown that potential toxin producing cyanobacteria are common in them with Microcystis and Cylindrospermopsis being predominant together with Anabaena, Lyngbya and Oscillatoria sometimes present. An article entitled "Is the Water we Drink Safe?" written by this author published in two parts in the Island of August 6th and 8th 2005, traced how the algal populations of our freshwater reservoirs have gradually changed from harmless species to toxin producing ones from the beginning to the end of the 20th century.
It is time that we focus our attention on the deterioration of inland water bodies that are natural resources essential for the sustenance of our rural population. Any stagnant water body under high light and temperature will usually sustain a small and diverse algal population. When such a water body gets polluted specially with nitrogen and phosphorus rich nutrients it undergoes eutrophication and further pollution could lead to hyper-eutrophication. Under such circumstances most of the sensitive algal species disappear leaving behind the resistant toxin producing cyanobacteria notably Microcystis, Cylindrospermopsis and Anabaena.
How do our reservoirs get such high concentrations of phosphorus? An excellent article on this aspect was published in the Island newspaper of Friday 6th February 2013. The authors of this article are leading soils scientists who have served the Department of Agriculture for several years and the principal author Dr. Sarath Amarasiri retired from service as the Director-General of Agriculture.
According to them our inland water bodies receives so much of phosphorus primarily due to the application of high levels of soluble phosphorus fertilizers like triple super phosphate, far in excess of what is required. In this manner we are not only wasting money on such fertilizers but also pollute our water bodies which pose a danger to the people. It is essential that we make the farmers and the general public aware so that they could be alert to this situation.
Dangers of Algae toxin
accumulation
Accumulation of algal toxins in water is dangerous. These toxins have been reported to contribute to liver and kidney ailments and some types of cancers. As these toxins are thermo stable they are not destroyed by boiling the water. These are cumulative poisons that could pass from lactating mothers to their infants. In this respect the state and all of us have a responsibility to protect not only the present but even the future generations from this danger.
It is imperative that the government coordinate the activities of the National Water Supply and Drainage Board, the Irrigation Department and the Agriculture Department and take some unified action to minimize the excessive use of soluble phosphorus fertilizer. If public awareness by itself does not have an impact, it may be necessary even to enact legislation to reduce this menace as done in certain countries according to the article of February 6th.
Pollutants in stagnant water
bodies
Most of these stagnant water bodies receive pollutants through inflows from canals, streams, rivers etc as particle bound colloidal matter. Certain countries minimize such pollution by growing reeds across the inflow pathways and planting pollutant absorbing trees along the banks of water reservoirs. Yet others introduce herbivorous fish and zooplanktons and reduce the populations of carnivorous fish species that prey upon algal consumers. These are some areas of research that we should embark upon in order to minimize this menace of toxigenic algae becoming predominant in our lakes and reservoirs.
The author is an Emeritus Professor of Botany, University of Peradeniya and is currently a Research Professor at the Institute of Fundamental Studies, Kandy.
He can be contacted at ananda@kulasooriya.com
In this special feature article to mark World Water Day today (22nd March), IPS researchers Chatura Rodrigo (Research Economist) and Athula Senaratne (Research Fellow) examine the usefulness of the ‘Integrated Water Resource Management’ approach as a solution to an impending water crisis.
Hydrologists and water resource economists have suggested that by 2030 one third of the world population will be based along river basins and the scarcity of water for agriculture will have a tremendous impact on their livelihoods. Overall, the world’s water demand will grow from 4500 billion cubic metres to 6900 billion cubic metres by 2030 - a 40% increase from the current water supply. Not only in the developing world but also in the developed world countries such a USA, Spain, Germany, and France, are already facing water scarcity for agriculture and have a limited supply of irrigation water for agricultural use. Therefore, policy makers around the world are now confronted with the challenge of formulating alternative strategies for water management to address these issues.
There is increasing evidence to suggest that water scarcity is likely to be aggravated further by the inevitable reality of climate change. The Intergovernmental Panel on Climate Change (IPCC) suggests that climate change affects all components of freshwater systems. As a result, water quality and availability will be major issues in the future. Today, close to 70% of the water in the world is used for agricultural purposes and of that, much is utilized by developing countries. Therefore, it is fair to say that, in the future, developing countries will be more affected by water scarcity for agriculture than developed countries. Climate change affects the intensity as well as the patterns of distribution of rainfall. The Food and Agriculture Organization (FAO) suggests that climate change will affect livelihoods of the rural masses, especially in developing countries, by limiting the water availability for agriculture. FAO suggests that the increased intensity of droughts and floods can also lead to widespread crop damages, thereby further affecting the livelihood security of farmers.
Ground Realities
Sri Lanka is heavily dependent on agriculture and both rain-fed and irrigated agriculture form the backbone of rural livelihoods. Scientists have suggested that the overall rainfall received by Sri Lanka has decreased in many areas of the country. The established patterns of rainfall have changed and the distribution of rainfall in different parts of the country also appears to be undergoing changes. While the droughts cause delays in planting seasons and are responsible for crop damages, floods have been destroying mature crops awaiting harvest.
According to current statistics, the total cultivated area in Sri Lanka is estimated at 1.86 million ha. About 632,000 ha. of this area is irrigated; the rest is rain-fed. Irrigated agriculture is mainly comprised of major irrigation schemes. In addition, there are numerous minor schemes, which can be identified as semi rain-fed systems. They include over 15,000 village tanks scattered across the dry zone areas of the country. Irrigated agriculture in Sri Lanka has received a great deal of attention from policy makers over the past several decades, which culminated in the accelerated Mahaweli Development Program in the mid 1980s. Many steps have been taken to rehabilitate and restore ancient irrigation systems.
Majority of the irrigated land in Sri Lanka is used for paddy cultivation. The demand for water is high in paddy cultivation compared to many other crops. Water is essential for the preparation of land, and the planting and maintenance of the crop throughout the planting-harvest cycle. On average, the water requirement for irrigated rice is between 900-2250 mm per day. By 2025, paddy cultivation area is projected to increase by 28%, with the annual growth in the cultivated area of paddy rising to 1077 ha, compared to 836 ha in 1991. Sri Lanka’s dry zone is the main paddy producing area in the country and some parts of this area will face an absolute scarcity of water by 2025. Furthermore, research has suggested that paddy production in Sri Lanka will increase by 10% by year 2025 and that additional amount will be totally irrigation-based.
Applying the IWRM Approach
To manage these challenges, experts have stressed the importance of an Integrated Approach of Water Resource Management (IWRM) to face the rising threat of water scarcity. The concept of IWRM was first proposed about 60 years ago and was re-examined in the 1990’s. IWRM calls for a holistic approach where agricultural water management is considered a part of an overall strategy of natural resource management. The way in which water is managed for agricultural purposes is a function of different management practices that are closely associated with the management of other natural resources as well. Accordingly, management of water will depend on the actions taken by the different users of water and other natural resources. For example, the management of water for agriculture from an irrigation tank largely depends on the management of the catchment area of the tank. The actions taken by the users of the catchment area will affect the water storage of the tank; thereby determining the availability of water for agriculture.
Even though IWRM has been discussed as the most sustainable way of managing water resources, there is some criticism as well. While it is attractive on a conceptual level, the implementation of macro- and meso-scale water resource management projects has faced certain difficulties. Among the reasons for this are the heterogeneity of water users and poor institutional arrangements. Evidence shows that farmers in Sri Lanka are moving towards intensive commercial agriculture, and privately oriented land/water management strategies are rapidly being adopted. As a result, the emerging agricultural systems have ignored the traditional practices of integrated management of associated resources, such as catchment areas.
However, experts have suggested that innovative ways of IWRM can be used to meet the future demand of water in developing countries. One innovative idea is the concept of "virtual water". Virtual water refers to the hidden or unobserved flow of water when commodities are traded from one country to another. The virtual water content of a commodity is the volume of water required to produce the commodity, which is measured at the original place of the production. This contains the sum of water use for that commodity at various stages of the production process. Therefore, if a country with scarce water resources is producing a particular commodity requiring a large quantity of water, then they could potentially import that commodity from another country that has relatively less water issues, and thereby save the water needed to actually produce that commodity in the country itself. Secondly, water-scarce countries can increase the efficiency of their water management practices through new technological/institutional strategies and water conservation. Thirdly, countries can use more efficient, economical, and environmentally- friendly approaches to prevent the pollution of water. Finally, naturally unusable water, such as saline and sodic water, can be treated to use for agricultural purposes with the use of new technologies. However, the application of these strategies should be compatible with country-specific needs and development agendas. With emerging technologies and private sector involvements, agricultural water management has become increasingly complex. Countries like the USA, China, Japan and Germany appear to have placed more faith on larger investments and modern technologies, while developing countries are focussing on adopting an IWRM approach.
Breaking with Tradition
There are significant efforts by governments over the past few years to establish new infrastructure, rehabilitate or renovate existing dams, reservoirs and canals, and promote agro wells and micro-irrigation technologies to meet the rising demand for agricultural water. Despite such efforts, however, the problem of water scarcity continues grow. In order to meet the future demands of agricultural water innovative approaches are needed. The demand for agricultural water has to be balanced with the municipal and industrial water demands. In balancing these demands, the goals of public health, environmental protection, economic viability, and food security need to be carefully assessed. The development of crop varieties that demand less water is one possible strategy to manage competing demands for water. The selective adoption of technologies appropriate for small farmers is another tool. Planning and coordinating irrigation water is also very important to save the excess use of water. Farmer organizations, local institutions, and state agencies such as the Agrarian Development Department, Department of Agriculture, Department of irrigation, and the Department of Meteorology all have an important role to play. They must work closely and share knowledge and information so that irrigation water can be better managed through an IWRM approach.
References
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Morrison J. Et al, 2009, "Water Scarcity and Climate Change: Growing risks for Business and Investors", The Pacific Institute.
United Nations News Centre, 2011, Climate Change Related Water Scarcity to Affect Global Food Production, http://www.un.org/apps/news/story.asp?NewsID=38673#.UUVERzdtiSo, visited on 17th March 2013.
Bouwer Herman, 2000, "Integreted Water Management: Emerging Issues and Challanges", Agriculture Water Management, Vol 45, PP. 217-228.
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Weerakoon W.M.W, Abeysekara A, and Wijesundara C, 2010, "Agronomic Strategies to Increase Rice Yield in Sri Lanka", Rice Research and Development Centre, Ibbagamuwa, and Regional Agriculture Research and Development Centre, Bombuwela, Sri Lanka.
Sandaratne, N,….. "The Paddy Paradox: Challenges in the Next Decade", Post Graduate Institute of Agriculture, University of Peradeniya, Sri Lanka, accessed online 18th March 2013.
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