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On the role of Remote Sensing in environmental impact analysis of shrimp farming
Tripathi. N. K
Space Technology Application and Research Program, School of Advanced Technology,
Asian Institute of Technology Bangkok, P.O. Box. 4,
Klong Luang, Pathumthani 12120, THAILAND
Tel: 66-2-524-6392, Fax: 66-2-524-5597 nitinkt@ait.ac.th
Annachchatre, A and ., Patil, A. A.
Environmental Engineering, School of Environment of Resource Development,
Asian Institute of Technology Bangkok, P.O. Box. 4, Klong Luang,
Pathumthani 12120, THAILAND
Tripathi. N. K
Space Technology Application and Research Program, School of Advanced Technology,
Asian Institute of Technology Bangkok, P.O. Box. 4,
Klong Luang, Pathumthani 12120, THAILAND
Tel: 66-2-524-6392, Fax: 66-2-524-5597 nitinkt@ait.ac.th
Annachchatre, A and ., Patil, A. A.
Environmental Engineering, School of Environment of Resource Development,
Asian Institute of Technology Bangkok, P.O. Box. 4, Klong Luang,
Pathumthani 12120, THAILAND
Abstract
Intensive shrimp farming has developed rapidly in response to dramatic increase in Seafood demand. It has become a thriving business in many developing countries including Thailand. Shrimp farming and aquacultural activities are mostly carried out in mangroves and coastal regions as they provide a nice habitat. But intensive shrimp farming has adverse impact on mangroves and marine environment. An attempt has been made to find the effect of effluent from shrimp ponds on neighboring surface water bodies in terms of suspended solids and organic matter. The residual salts from the dried shrimp ponds are generally thrown on nearby land. This is causing serious salinity of the soil thus making the arable land infertile and turning them into wasteland. As a case study, a coastal province of Thailand has been undertaken. This paper investigates the environmental impact of shrimp farming on landuse pattern, surface water bodies, marine water, mangrove forests and agricultural land using satellite data.
Introduction
Thailand has experienced rapid growth in shrimp farming in response to dramatic increase in seafood demand and decline in natural fisheries due to pollution and over exploitation. It has developed rapidly into a thriving business in many countries and has provided more than 25% of world's annual shrimp market since 1990. In 1994, 733,000 metric tons of shrimp from 1,144,000 ha of ponds were produced in which tiger shrimp (Penaeas monodon) was most dominant species comprising about 61% of total shrimp production (Rosenberry 1994) and it is still increasing.
Despite the apparent economic success of intensive shrimp farming, its sustainability has been a major concern of the industry. The externalities associated with modern production have become increasingly evident and now confront difficult problems related to effluent discharge (Landesman 1994). The effluent laden discharge form shrimp pond can be a potential for nutrient enrichment and eutrophication of natural water bodies and its impact on coastal environment has caused greater concern (Phillips et. al. 1993). Increasing, eutrophication in natural water can lead to ecologically undesirable consequences. Shrimp farming, while generating important benefits has also contributed to degradation of coastal environment and this threatens sustainability of the production. The risk of failure increases with greater stocking density, which requires extra intensive management, meaning more food input, more water exchange. It relates directly to greater amount of waste being produced in the ponds, which may eventually reach the flash point of pond carrying capacity by poisoning with excessive waste.
Shrimp farming and Aquacultural activities are mostly carried out in mangroves and coastal regions all over the world. The intensive shrimp farming has significant impact on mangroves and marine environment as well. It has been realized that the polluted water discharge from shrimp farms causes deterioration of water quality of adjacent water bodies like mangroves and coastal zone. Coastal zones are places of ending changes. Effective inventorying and monitoring of these changes are required for the understanding and managing these environments (Pundharikanthan, 1997).
There are many conventional methods to find out the impact of all concentrations on the ecosystem. These conventional methods only give us the concentration of pollutant at a particular point or so but can not show the dispersion pattern or extent of pollution at the same time. Much harder to detect is pollution that has had great length of time to disperse and hence cover large area, or pollution that does not emanate from a point source (Clark, 1993).
Remote sensing provides better tool to serve all these purposes to give synoptic coverage of water bodies. The greatest advantage of remote sensing technology is that it provides augmented view of spatial and temporal variability of water quality and land use status which can not be obtained by any conventional measuring techniques. Several workers have utilized the satellite remote sensing and GIS for detecting and analysing water qualities like ch-a, SSC, Chemical composition etc. (Alfoldi (1982), Lathrop and Lillesand (1991), Clark (1993)).
In the present study an attempt is made to determine the environmental changes that has occurred due to shrimp farming in Ranong, Thailand. The interpretation from satellite data has been compared with past records to estimate the changes. The focus in present work being discussed in this paper is effect on water quality and degradation in forest and mangrove area.
Study Area
The study area is located at western coast of Thailand. It has extensive mangrove forests and dense tropical vegetation. The vegetation predominantly comprises of evergreen forests, coconut, rubber and palm plantations. The shrimp farms are frequently seen inside the mangroves or adjacent to it. The physical location of the study area can be given as 9o 50¢ 00¢¢ N to 10o 00¢ 00¢¢N and 98o 30¢ 00¢¢ E to 98o 40¢ 00¢¢ E. The study area is shown in figure 1. The study area has high hill ranges that are covered with tropical rain forests. There are numerous streams flowing down these hills carrying silt and organic wastes in the marine regions.
Landsat TM digital image in all the bands has been acquired for the study region falling under scene path no. 130 and row no. 053. Topographic map nos. NC 47-6 and NC 47-10 were used for generating the base map and geo-referencing the satellite data.
Methodology
Landsat TM bands have been analysed for better understanding and interpretability of marine and coastal vegetation cover. It is found that FCC generated with bands 432 has offered a synaptic coverage revealing the landuse categories such as vegetation species, urban dwellings, shrimp farms, river channels, and suspended sediments. In addition it is found that FCC 531 was more useful in extracting information on minor channels and effluents from shrimp farms. The different vegetation species have also become very distinct in this band combination. Using these two products the areas covered by shrimp farms have been delineated and an inventory has been prepared. By traditional surveying this task is very difficult and often not possible. The pollution control authorities have strict instructions to treat the wastewater and then shrimp farmers are allowed to dump in adjoining channels but rarely such treatment is carried out. There is no check in absence of viable monitoring techniques. In FCC 531 it is evident that effluent from shrimp farms is of different quality showing yellowish shade. This waste is generally a amino compound which are fed to shrimps in form of proteins. The effect of this and other waste regularly dumped in streams is toxic and has adverse effect on fishery and other aquatic life.
Environmental Impact Due to Shrimp Farming
From the published records and inventory from satellite data an analysis is shown in Figure 3 on degradation of mangrove areas in the study area. It is evident that there is gradual decline in mangrove areas since 1961 till 1996. The reason of loss in mangrove
Area is attributed to rapid growth in shrimp farming in the region. Shrimp farms are generally developed by clearing mangroves and using the easily available seawater for the ponds. The effluent from Shrimp ponds find a way to the adjoining channels and are further transported to the sea.
Figure 1 Marine environ of Ranong (Thailand)
Landsat band1 image (Figure 1) shows the setting of shrimp farms inside the mangrove areas. These are generally situated near seacoast and adjoining channels. Figure 2, offers a very detailed view of a cluster of shrimp farms. Shrimp farms are generally used for a period of five years for intensive farming. After that, they loose their fertility and are abandoned or regenerated after dredging the settled waste material. These abandoned ponds are having large salt deposits and can not be used for agriculture purpose. Shrimp farming cause following environmental degradation:
Figure 2 Shrimp farms in mangrove areas(Thailand)
In present study the loss of mangrove forest areas has been highlighted using Landsat TM data. The mangrove forest is considered the most important coastal ecosystem in terms of primary production and coastal protection. Thailand's mangrove forests have seriously depleted in last decade. There is strong realization for intensive monitoring using remote sensing techniques and also restrict shrimp farming to non-mangrove areas.
Abandoned shrimp farms are easily located on FCC432 due to their dull brown colour which is in contrast to active shrimp farms with blue colour. These abandoned farms have soil laden with thick wastes in farm of nitrogen and phosphorous and salts. It is useless for any fruitful agriculture.
During shrimp farming various external additives like feeding pallets, fertilizers, and other chemicals are being added to farm. Those additives can not be utilized by the culture completely for its growth, so they settle down or get dissolved in the water. Frequently this water which is contaminated is dumped in freshwater streams thus making them polluted. Tha main contaminants in this process can be listed as nutrients, dissolved oxygen, dissolved organic matter etc.
Conclusion
The work presented in this paper is part of the major ongoing project on Ranong area. The priminary investigations have confirmed the usefulness of Landsat TM digital image in delineating degradation in mangrove areas. Active and abandoned shrimp farms have also been located using different false colour composites. On visual interpretation of band 1 it is found that sediment concentration can be monitored. FCC 531 has also shown a yellow colour effluent from shrimp farms entering the streams. Based on the outcome of this study, authors are currently engaged to investigate more on quantitative information extraction on water quality deterioration in shrimp farm areas using multi-band satellite digital image.
References
Intensive shrimp farming has developed rapidly in response to dramatic increase in Seafood demand. It has become a thriving business in many developing countries including Thailand. Shrimp farming and aquacultural activities are mostly carried out in mangroves and coastal regions as they provide a nice habitat. But intensive shrimp farming has adverse impact on mangroves and marine environment. An attempt has been made to find the effect of effluent from shrimp ponds on neighboring surface water bodies in terms of suspended solids and organic matter. The residual salts from the dried shrimp ponds are generally thrown on nearby land. This is causing serious salinity of the soil thus making the arable land infertile and turning them into wasteland. As a case study, a coastal province of Thailand has been undertaken. This paper investigates the environmental impact of shrimp farming on landuse pattern, surface water bodies, marine water, mangrove forests and agricultural land using satellite data.
Introduction
Thailand has experienced rapid growth in shrimp farming in response to dramatic increase in seafood demand and decline in natural fisheries due to pollution and over exploitation. It has developed rapidly into a thriving business in many countries and has provided more than 25% of world's annual shrimp market since 1990. In 1994, 733,000 metric tons of shrimp from 1,144,000 ha of ponds were produced in which tiger shrimp (Penaeas monodon) was most dominant species comprising about 61% of total shrimp production (Rosenberry 1994) and it is still increasing.
Despite the apparent economic success of intensive shrimp farming, its sustainability has been a major concern of the industry. The externalities associated with modern production have become increasingly evident and now confront difficult problems related to effluent discharge (Landesman 1994). The effluent laden discharge form shrimp pond can be a potential for nutrient enrichment and eutrophication of natural water bodies and its impact on coastal environment has caused greater concern (Phillips et. al. 1993). Increasing, eutrophication in natural water can lead to ecologically undesirable consequences. Shrimp farming, while generating important benefits has also contributed to degradation of coastal environment and this threatens sustainability of the production. The risk of failure increases with greater stocking density, which requires extra intensive management, meaning more food input, more water exchange. It relates directly to greater amount of waste being produced in the ponds, which may eventually reach the flash point of pond carrying capacity by poisoning with excessive waste.
Shrimp farming and Aquacultural activities are mostly carried out in mangroves and coastal regions all over the world. The intensive shrimp farming has significant impact on mangroves and marine environment as well. It has been realized that the polluted water discharge from shrimp farms causes deterioration of water quality of adjacent water bodies like mangroves and coastal zone. Coastal zones are places of ending changes. Effective inventorying and monitoring of these changes are required for the understanding and managing these environments (Pundharikanthan, 1997).
There are many conventional methods to find out the impact of all concentrations on the ecosystem. These conventional methods only give us the concentration of pollutant at a particular point or so but can not show the dispersion pattern or extent of pollution at the same time. Much harder to detect is pollution that has had great length of time to disperse and hence cover large area, or pollution that does not emanate from a point source (Clark, 1993).
Remote sensing provides better tool to serve all these purposes to give synoptic coverage of water bodies. The greatest advantage of remote sensing technology is that it provides augmented view of spatial and temporal variability of water quality and land use status which can not be obtained by any conventional measuring techniques. Several workers have utilized the satellite remote sensing and GIS for detecting and analysing water qualities like ch-a, SSC, Chemical composition etc. (Alfoldi (1982), Lathrop and Lillesand (1991), Clark (1993)).
In the present study an attempt is made to determine the environmental changes that has occurred due to shrimp farming in Ranong, Thailand. The interpretation from satellite data has been compared with past records to estimate the changes. The focus in present work being discussed in this paper is effect on water quality and degradation in forest and mangrove area.
Study Area
The study area is located at western coast of Thailand. It has extensive mangrove forests and dense tropical vegetation. The vegetation predominantly comprises of evergreen forests, coconut, rubber and palm plantations. The shrimp farms are frequently seen inside the mangroves or adjacent to it. The physical location of the study area can be given as 9o 50¢ 00¢¢ N to 10o 00¢ 00¢¢N and 98o 30¢ 00¢¢ E to 98o 40¢ 00¢¢ E. The study area is shown in figure 1. The study area has high hill ranges that are covered with tropical rain forests. There are numerous streams flowing down these hills carrying silt and organic wastes in the marine regions.
Landsat TM digital image in all the bands has been acquired for the study region falling under scene path no. 130 and row no. 053. Topographic map nos. NC 47-6 and NC 47-10 were used for generating the base map and geo-referencing the satellite data.
Methodology
Landsat TM bands have been analysed for better understanding and interpretability of marine and coastal vegetation cover. It is found that FCC generated with bands 432 has offered a synaptic coverage revealing the landuse categories such as vegetation species, urban dwellings, shrimp farms, river channels, and suspended sediments. In addition it is found that FCC 531 was more useful in extracting information on minor channels and effluents from shrimp farms. The different vegetation species have also become very distinct in this band combination. Using these two products the areas covered by shrimp farms have been delineated and an inventory has been prepared. By traditional surveying this task is very difficult and often not possible. The pollution control authorities have strict instructions to treat the wastewater and then shrimp farmers are allowed to dump in adjoining channels but rarely such treatment is carried out. There is no check in absence of viable monitoring techniques. In FCC 531 it is evident that effluent from shrimp farms is of different quality showing yellowish shade. This waste is generally a amino compound which are fed to shrimps in form of proteins. The effect of this and other waste regularly dumped in streams is toxic and has adverse effect on fishery and other aquatic life.
Environmental Impact Due to Shrimp Farming
From the published records and inventory from satellite data an analysis is shown in Figure 3 on degradation of mangrove areas in the study area. It is evident that there is gradual decline in mangrove areas since 1961 till 1996. The reason of loss in mangrove
Area is attributed to rapid growth in shrimp farming in the region. Shrimp farms are generally developed by clearing mangroves and using the easily available seawater for the ponds. The effluent from Shrimp ponds find a way to the adjoining channels and are further transported to the sea.
Figure 1 Marine environ of Ranong (Thailand)
Landsat band1 image (Figure 1) shows the setting of shrimp farms inside the mangrove areas. These are generally situated near seacoast and adjoining channels. Figure 2, offers a very detailed view of a cluster of shrimp farms. Shrimp farms are generally used for a period of five years for intensive farming. After that, they loose their fertility and are abandoned or regenerated after dredging the settled waste material. These abandoned ponds are having large salt deposits and can not be used for agriculture purpose. Shrimp farming cause following environmental degradation:
- Loss of mangrove forest or fertile land
- Degradation of the soil due to salinization
- Deterioration of water quality
Figure 2 Shrimp farms in mangrove areas(Thailand)
In present study the loss of mangrove forest areas has been highlighted using Landsat TM data. The mangrove forest is considered the most important coastal ecosystem in terms of primary production and coastal protection. Thailand's mangrove forests have seriously depleted in last decade. There is strong realization for intensive monitoring using remote sensing techniques and also restrict shrimp farming to non-mangrove areas.
Abandoned shrimp farms are easily located on FCC432 due to their dull brown colour which is in contrast to active shrimp farms with blue colour. These abandoned farms have soil laden with thick wastes in farm of nitrogen and phosphorous and salts. It is useless for any fruitful agriculture.
During shrimp farming various external additives like feeding pallets, fertilizers, and other chemicals are being added to farm. Those additives can not be utilized by the culture completely for its growth, so they settle down or get dissolved in the water. Frequently this water which is contaminated is dumped in freshwater streams thus making them polluted. Tha main contaminants in this process can be listed as nutrients, dissolved oxygen, dissolved organic matter etc.
Conclusion
The work presented in this paper is part of the major ongoing project on Ranong area. The priminary investigations have confirmed the usefulness of Landsat TM digital image in delineating degradation in mangrove areas. Active and abandoned shrimp farms have also been located using different false colour composites. On visual interpretation of band 1 it is found that sediment concentration can be monitored. FCC 531 has also shown a yellow colour effluent from shrimp farms entering the streams. Based on the outcome of this study, authors are currently engaged to investigate more on quantitative information extraction on water quality deterioration in shrimp farm areas using multi-band satellite digital image.
References
- Alfoldi T.T., 1982, Remote sensing for water quality monitoring. In Remote sensing for resources management, edited by C. J. Johannsen and J. L. Sanders (Ankey Iowa: soil conservation society of America). Pp. 317-328.
- Clark C.D., 1993, Satellite and remote sensing of marine pollution. International Journal of Remote Sensing Vol. 14 No. 16: 2985-3004.
- Landesman L., 1994, Negative impacts of coastal Aquaculture development World Aquaculture. 25, 12-17 pp
- Lathrop, R.G. and Lillesand T.M., 199, Testing the utility of simple multi-date thematic mapper calibration algorithm for monitoring turbid inland waters. International Journal of Remote Sensing, Vol.12: 2045-2063.
- Phillips M.J., Lin C.K. and Bereridge M.C.M. 1993, shrimp culture and environment lessons from world's most rapidly expending warm water Aquaculture sector. Environmental and Aquaculture in Development Countries (Ed. By R.S.V. Pullin, H. Roenthal and T. L. Madean) I.C.Larm conference proceedings 31, 171-197.
- RAS/86/120, 1991, Integerated multidisciplinary survey and research programe of the Ranong mangrove ecosystem, UNDP/UNESCO Regional project-research and its application to the management of the mangroves of Asia and the Pacific.
- Rosenberry R., 1994 A new record world shrimp farming; Shrimp news international December 1994 pp 1-29