EUTROPHICATION: A SILENT KILLER OF LAKES

Shrinking of water bodies, “foul smell of lakes”, fish kills in summer, enormous macrophytic growth and ecosystem threats in Kashmir! What is the common link?

Dr. Ummer Rashid Zargar
Srinagar, Publish Date: Oct 26 2017 11:31PM | Updated Date: Oct 26 2017 11:31PM
EUTROPHICATION: A SILENT KILLER OF LAKES

The straightforward answer is, nutrient enrichment of lakes. Eutrophication is the nutrient enrichment of waters that stimulates an array of symptomatic changes that can include increased phytoplankton and rooted aquatic plant (macrophyte) production, fisheries and water quality deterioration, and other undesirable changes that interfere with water uses. For a layman eutrophication is simply a nutrient enrichment or fertility of lake. The impacts of eutrophication are more severe than recognized. Vonlanthen and his co-workers (Nature, 2012) provided an evidence that eutrophication can lead to extinction or ‘speciation reversal’ and ‘demographic reversal’ in Whitefish across European Lakes. 

Eutrophication is most often the result of an elevated supply of nutrients, particularly nitrogen and phosphorus, to surface waters that results in enhanced production of primary producers, particularly phytoplankton and aquatic plants. As per report of Moore and his associates published in 2003, Nutrient pollution and associated eutrophication of freshwaters threaten the ecological integrity and the services provided to humans by lakes. Global warming and climate change has been additive factors for eutrophication as nutrient enrichment has shown signs of link with the global climatic change.

Anthropogenic eutrophication has become a global problem, affecting many marine systems (US, EU, China, Japan, Australia and elsewhere) as well as fresh water systems. The extreme eutrophication of lakes and water bodies can have major impact on aquatic flora and fauna. The resulting ecologic effects of eutrophication, including habitat destruction, shifts in species composition and distribution range, invasion of non-native species, and changes in food web efficiency, are increasingly apparent in both fresh water as well as marine water bodies. 

The water bodies of Kashmir Valley, especially lakes are facing cultural eutrophication. Water pollution shadows human population growth and development and is caused by diffuse (non-point) and concentrated (point) nutrient enrichment, especially Total Phosphate and Nitrates. The ill effects of eutrophication are at its peak. The loss of endemic fish fauna can be attributed to the decreased water quality in last three decades, although other factors have also contributed in this cause. The fish kill in Nigeen Lake, 2012 summer, is a clear proof how degraded water quality can badly affect the survival of aquatic fauna. Sudden mortality of fish in Nageen Lake, as per concerned authorities, was due to depleted dissolved oxygen and alteration in temperature, although few suggested its link with global warming.  In addition, nutrient loading during the summer months increases to greater extent which leads to unwanted growth of macrophytes and finally affects the water quality. In broader context, Nigeen episode warned us against big catastrophe in coming years, as we witness fish kill on small scale in different lakes which remain unnoticed. 

Natural Eutrophication is a natural or an evolutionary process which slowly and steadily transforms a water body or a lake from an oligotrophic to hypertrophic condition. However, such a process is very slow and takes hundreds of years to complete. The condition our lakes are facing is the accelerated eutrophication, which is the abrupt hike in the contamination of lakes through phosphorus inputs. At present, we are left with few lakes whose condition is still conducive for aquatic life. It has been stated by experts that all lakes in Kashmir are undergoing eutrophication, though the pace of eutrophication differs from one lake to another. 

Eutrophication has already put lot of pressure on the limited aquatic resources and has also encouraged the growth of invasive weeds. Recent evidences suggest that unwanted weeds have engulfed urban lakes of Kashmir, especially Dal Lake. Dal Lake is presently engulfed with the obnoxious weeds including dangerous Azola. The massive growth of these weeds have been an alarm bell for authorities as Dal Lake is evolving from eutrophic state to hypertrophic state. This is not the first time that the water body in Kashmir shows massive bloom of alien species. Dinoflagellate bloom, red bloom and macrophytic bloom have been already reported in past which indicate that all is not well in our lake ecosystems. It is speculated that some lakes may be wiped out in next few centuries if there is no immediate rescue operation started (needs experimental base). 

Fish, which is an important economic resource for inhabitants of Valley has been badly affected by eutrophication and pollution. Many native species have already lost their breeding grounds in past thirty years due to excessive fertilization of lakes. Eutrophication has already proved to be fatal for the survival of fish fauna.

There are ample evidences that Lake Eutrophication in Kashmir has badly affected both fauna and flora and the situation calls for immediate attention from our part. Although in past lot of efforts have been made to combat the deleterious effects of eutrophication, but we have not achieved the set goals. An argument is commonly followed in Kashmir that mitigation programmes either started by government or NGO’s, in the last ten to twenty years have yielded nothing.  They further argue that previous mitigation plans were insufficient to tackle the deleterious effects of eutrophication because there was lack of vision and intent that was needed to curb the impacts of polluted water. However, we should not be disheartened as we can still take initiatives by making amendments in the management plans that are according to international standards. 

It is potentially much easier to preemptively avoid eutrophication than to attempt restoration of eutrophic lakes. The main focus of the lake management programme in Kashmir should be to halt nutrient loads coming from outside. Although, some initiatives are in place to prevent the entry of external nutrients, but present condition calls for a more vibrant mechanism to restrict the phosphate and nitrate components into the lake. Lake authorities should also keep watch on internal loading of lakes which has been reported in some lakes to be a component significant of annual nutrient load. According to Søndergaard and his co-workers (2003, Hydrobiologia), internal loading may prevent improvements in water quality even after having full control over external nutrient loading. It is pertinent to suggest future researchers to take up both of these aspects to investigate the possible impact of both internal and external loading in our water bodies by using advanced study designs. 

There is an urgent need for the universal regulation of nutrients around the lakes to protect drinking water supplies and aquatic biodiversity. To achieve this goal, LAWDA in Kashmir need to hire modern gadgets for surveillance purpose. Day-to-day monitoring of lakes through well planned manner will help us to keep up to date information about the contamination level. 

 General public in Kashmir is unaware about the real situation of water bodies partly due to the fact that the message is not communicated properly by the authorities in general public. It is the duty of local authorities to inform public in areas where there is any major risk from enhanced eutrophication to humans or aquatic organisms. There is need of full public participation at different levels while starting any rehabilitation program so that they are convinced that safety of water bodies lies in the hands of local population. The commination gap is still wide between authorities and public as narratives differ regarding the conservation of lake water bodies. The modern, fast communication methods like social websites, radio, television and internet can be geared up to serve the purpose. Local authorities should also install temporary warning signs along the water bodies affected by the bloom or anoxic condition. 

In sum, enhanced eutrophication is a major concern for lake authorities as well as to the general public in Kashmir. Lake eutrophication has already reached to the alarming rate in last three decades and is predicted that it may create a great mess in near future. Although, it is a general perception in Kashmir that future of our lakes is bleak, however, political will and local support can change the scenario in a big way.  

Dr. Ummer Rashid Zargar is SERB_DST Fellow, Department of Zoology, Central University of Kashmir. The views expressed in the article are authors own and does not reflect the views of the Institute or the Organization with which he is associated