HANDBOOK 4 WATER POLLUTION

Transcription

1 Natural Resources and Environment Board Sarawak HANDBOOK 4 WATER POLLUTION Monitoring of Fish shrimps and prawns (Kuching Rivers)

2 HANDBOOK 4 WATER POLLUTION Monitoring of Fish, shrimps and prawns (Kuching Rivers) Erling Povlsen April 2006

3 Handbook 4 Water Pollution Monitoring of Fish shrimps and prawns The use of number of species, total abundance and abundance of indicator species as indicators for water quality of rivers Erling Povlsen, COWI A/S, Consulting Engineers and Planners 1 st Edition (1 st Print) April copies The Authors, Natural Resources and Environment Board, Sarawak and Danida Copenhagen Quotation permitted with source credit Printed by UM Colour Printing Co. Report No. UEMS_TEC_02-60

4 Table of Contents FOREWORD 1 1. INTRODUCTION 3 2. MONITORING PARAMETERS 4 3 MONITORING STRATEGY AND PROCEDURE Field work Fish identification Data presentation and reporting 7 6. REFERENCES 19

5 FOREWORD The Natural Resources and Environment Board, Sarawak (NREB) assisted by the Sarawak Government/DANIDA Sustainable Urban development (SUD) project ( ) and the Urban Environmental Management System (UEMS) project ( ) has undertaken a number of surveys to identify indicator parameters for the future monitoring of river quality and health in Sarawak. Since 1998 the NREB has monitored a number of physical/chemical river water quality parameters. These parameters are, however, only partly able to describe the environmental quality of the river and the potential impact imposed on it by the fast economic development. In urban areas and other areas especially intensive influenced by development, additional parameters are required. The surveys undertaken were initiated to identify these parameters. The NREB publishes the developed standards for these parameters in a series of handbooks. In 2001 the NREB published guidelines for odour measurements in water (NREB Handbook 1. Water Pollution. Determination of odour concentrations in water (SUD-02-29) and in 2002 the NREB published guidelines for measurements of river bed sediment and benthic fauna (NREB Handbook 2. Water Pollution. Monitoring of sediment and river bed invertebrate fauna). In 2005 a handbook on oil and grease traps was published (NREB Handbook 3 Water Pollution. Guidelines on the oil and grease trap sizing for food outlets (UEMS_TEC-02_49). This handbook is the fourth publication in the series. The handbook describes the parameters related to the abundance of fish, prawns and shrimps in rivers. The handbook describes a procedure for monitoring of fish, shrimps and prawns in rivers and streams within the city of Kuching. The development of the parameters is based on one year of fishing at 8 sites along the urban stretches of Sg Sarawak, Sg Kuap and Sg Maong, Kuching This fishing survey is documented in the report "NREB

6 Fish shrimps and prawns as indicators of pollution of Kuching Rivers"(UEMS_TEC_02-65). I would like to take this opportunity to record our gratitude to Danida for its support. In addition, I would like to record our appreciation to the many individuals from various Federal and State Government departments, who provided valuable support and cooperation in this matter. "TOWARDS TOTAL ENVIRONMENTAL QUALITY MANAGEMENT" CHONG TED TSIUNG Controller of Environmental Quality / Project Director Natural Resources and Environment Board / Urban Environmental Management System Project SARAWAK 2

7 1. INTRODUCTION Fishes have been used as indicators for pollution and other environmental changes in marine, estuarine and freshwater environments for a long time (Ward et. al.1998, Stephens et. al.1988, Brown, 2000). Fish are well suited as indicators because they are generally large and relatively easy to identify. Some fish species are sensitive to changes in the physical, chemical and biological quality of their habitat while others are not. In addition deleterious effects on fish due to pollution are of particular public interest because fish are exploited for food and recreation. A survey on the use of fish, prawns and shrimps as indicators for river quality in Sarawak was carried out in Sg. Sarawak, Sg Kuap and Sg Maong in Kuching City, Sarawak during the period October 2003-August The aim of the survey was to: 1 Identify appropriate fishing method (fishing gear, fishing time, fishing season etc.) for the future monitoring 2 Identify the existing fish, shrimp and prawn fauna in Sg Sarawak and tributaries, and document their distribution in relation to water quality 3 Identify indicator species for polluted and unpolluted river water and 4 Elaborate methods for data interpretation and presentation. The outcomes of the survey are: The report "Fish shrimps and prawns as indicators of pollution of Kuching Rivers"Vol I and II (UEMS_TEC_02-65). Katherine Atack: "A field guide to the fishes of Kuching Rivers" Natural History Publications (Borneo), 2006) 3

8 This handbook on the use of fish, shrimps and prawns as indicators for rivers quality. The methods described in this handbook have been developed for the lower reaches of Sg Sarawak and its tributaries in Kuching, where tidal influence is small due to the barrage. The method cannot be used for upper stretches of rivers in Sarawak because the indicator species for polluted and clean water would be different from those identified for Sg Sarawak and its tributaries. Care should also be taken for using the identified indicator species in rivers strongly influenced by tide and where salinity fluctuates significantly on a daily basis. 2. MONITORING PARAMETERS The survey has identified the following parameters as indicators for the environmental quality of rivers: Total abundance of fish, shrimps and prawns (expressed as CPUE (cf. below) Total number of species of fish, shrimps and prawns Diversity of fish, shrimps and prawn populations Abundance of indicator species 3. MONITORING STRATEGY AND PROCEDURE 3.1 Field work Fishing sites and strategy In order to be able to correlate the fishing data with environmental data, fishing should be carried out at or close to the monitoring sites for water and sediment quality. In addition, field measure- 4

9 ments of salinity, dissolved oxygen and turbidity must be carried out during the fishing (cf. below) Fishing time Fishing is carried out twice a year: In November (during the wet season) and In June (during the dry season) For each of the two fishing months fishing are carried out for 5 days at each site. It is recommended that one gill net is deployed each day on each site for 5 hours (see below) Fishing methods Fishing is done by Jaring nets (gills nets). It is recommended to use a net that is 70 feet long and 6 feet deep of the three-layer type (i.e. a small mesh size in the centre (38 mm) and two large mesh sizes on the outer sides (96.5 mm). The nets are deployed in the morning and left for 5 hours before being hauled. As far as possible the fish are identified and counted in the field. The fish are then transferred to cooling boxes with ice and transported to the laboratory for confirmation of field identification and final counting of numbers of individuals of different species. 5

10 Figure 1. Fishing by the use of Jaring nets Field measurements The salinity, oxygen concentration and turbidity of the water at the fishing site are measured by portable field equipment before setting the nets and after hauling. Measurements shall be undertaken in three different depths: In the surface water (i.e. immediately beneath the surface); 6

11 In mid-water (i.e. in the water depth half between the surface and the sea-bed); and In bottom water (i.e. the water layer immediately above the seabed). The reason for measuring in three depths at each site is that due to saline stratification, oxygen depletion may occur in the bottom water while high concentrations are encountered in the surface water layers Field notes At each fishing site the following is noted: Length of the applied net Fishing time Number of individuals of different species caught Conditions during fishing in terms of: 1) Water flow speed. It is noted whether the water is stag nant, slow flowing or fast flowing. 2) Water flow direction. It is noted whether the water is outgoing or ingoing. 3) Weather conditions. It is noted whether it is raining, cloudy, sunny and/or windy. 3.2 Fish identification The fish are identified to species level as far as possible using the field guide for the fish of Sg Sarawak (Atack 2005). The numbers of individuals of each species are counted. 3.3 Data presentation and reporting The catch data are registered together with water and sediment quality data from the physical/chemical water quality monitoring (such as NREBs water quality monitoring programme) and the results of the field measurements of salinity, oxygen concentration and turbidity carried out during the fishing. 7

12 Regarding Sg. Sarawak it is important that data on the barrage operation during the fishing month is obtained (i.e. hours of opening/hours and amount of inflow and outflow). This is essential for the interpretation of the data. 4. MONITORING PARAMETERS 4.1 Total abundance of fish, shrimps and prawns The abundance of each species on each catch location is expressed as catch per unit effort (CPUE). CPUE is the aggregation of the numbers of individuals of each species per standard length of net per standard length of time. Catch per 70 meter net per 5 hours fishing are recommended. Alternatively the numbers caught per 1m of net length per hour of fishing may be used. 4.2 Total number of species of fish, shrimps and prawns The total number of species of fish shrimps and prawns is the total number of species identified in at least one catch at the site during the fishing month. 4.3 Diversity of fish, shrimps and prawn populations The Shannon Wiener (H ) and Margalefs (D) indices are used to assess the diversity and species richness of the fish, shrimp and prawn fauna. The Shannon Wiener index is calculated as: s H` = n i /n ln (n i /n) i =1 where s = number of species n = total number of individuals (expressed as total CPUE) n i = number of individuals of species i (expressed as CPUE) 8

13 Shannon-Wiener index mg/l The Margaleff index is calculated as: D = (s-1)/ln n, where s = number of species n= number of individuals (expressed as CPUE) As will appear from fig 2 the diversity decreases with increasing level of organic pollution measured as decreasing oxygen concentration in the water. 2,5 2 1,5 1 0,5 0 S8 S4 S6 SM2 SM1 3,5 3 2,5 2 1,5 1 0,5 0 Shannon-Wiener Oxygen in water Figure 2. Shannon-Wiener diversity of species of fish and shrimps caught in Sg Sarawak (S8, S4, and S6) and Sg Maong (SM1 and SM 2) in October 2003 (wet season) compared to the concentrations of oxygen on the sites Abundance of Indicator species An indicator species is a species selected for its sensitivity or tolerance to pollution. Sg Sarawak and Sg Maong in Kuching are polluted by discharges of untreated and insufficiently treated sewage and wastewater. The survey has demonstrated that fish, shrimps and prawns in these waters are affected by the poor water quality. 9

14 Table 1 and 2 presents the indicator species for poor water quality and indicator species for good water quality, respectively, identified for Sg Sarawak and Sg Maong. The indicator species are found in freshwater (0-1 o / oo salinity) and in slightly brackish water (0.5-5 o / oo ) and some of the species even at higher salinities Indicators for poor water quality Table 1. Indicator species for poor water quality in freshwater or slightly brackish water in lowland floodplains Species Nile tilapia Oreochromis niloticus niloticus Snakeskin gourami Trichogaster pectoralis Moonlight gourami Trichogaster microlepis Liposarcus pardalis Tarpon Megalops cyprionoides Ecology A freshwater species that can live in brackish water at salinities up to o / oo. Hardy opportunistic feeder that can live in polluted environments. Species introduced for aquaculture. Reared in ponds organically enriched with livestock waste (faeces, urine, spilled animal feed) and with low oxygen concentration Can live in low oxygenated conditions and can breathe directly from air. Aquaculture species. Reared in ponds organically enriched with livestock waste (faeces, urine, spilled animal feed) and with low oxygen concentration Aquaculture species. Can breathe directly from air. Reared in ponds organically enriched with livestock waste (faeces, urine, spilled animal feed) and with low oxygen concentration Freshwater species can breathe air to some extent. Introduced species. Locally named after the government cleaning body Ikan DBKU this species is hardy and can live in polluted and low oxygenated waters. Can tolerate low oxygen conditions by breathing air into a lung like air bladder 10

15 Figure 3. Nile tilapia (Oreochromis niloticus niloticus). Indicator for poor water quality. (Photo: Chíen C. Lee). Figure 4. Snakeskin gourami (Trichogaster pectoralis). Indicator for poor water quality. (Photo: Chíen C. Lee). 11

16 Figure 5. Moonlight gourami (Trichogaster microlepis). Indicator for poor water quality (Photo: Chíen C. Lee). Figure 6. Liposarcus pardalis. Indicator for poor water quality (Photo: Chíen C. Lee). 12

17 Indicators for good water quality Table 2. Indicator species for good water quality in freshwater or slightly brackish water in lowland floodplains. Species Carinotetraodon borneensis Yellowtail rasbora (Rasbora tornieri) Kryptopterus cryptopterus Fire eel Mastacembelus erythrotaenia Giant freshwater prawn Macrobrachium rosenbergii Ecology Freshwater species. Currently only known from southern Sarawak Freshwater species. Occurs in streams, canals and ditches in lowland floodplains Freshwater species. Occurs in large rivers with turbid water and in streams and canals A lowland floodplain species occurring in slow moving rivers and inundated plains. A freshwater species that migrate to brackish water to spawn Figure 7. Carinotetraodon borneensis. Indicator for good water quality (Photo: Chíen C. Lee). 13

18 Figure 8. Yellowtail rasbora (Rasbora tornieri) Indicator for good water quality (Photo: Chíen C. Lee). Figure 9. Kryptopterus cryptopterus Indicator for good water quality (Photo: Chíen C. Lee). 14

19 Figure 10. Fire eel Mastacembelus erythrotaenia. Indicator for good water quality (Photo: Chíen C. Lee). Figure 11. Giant freshwater prawn (Macrobrachium rosenbergii). Indicator for good water quality (Photo: Chíen C. Lee). 15

20 When using the indicators species care should be taken in interpretation if the salinity is higher than about 5 o / oo. On rivers strongly influenced by tide with a large diurnal variation in salinity, the identified indicators species cannot be used. In such areas use of abundance, number of species and diversity can be used as monitoring parameters for water quality. 5. PRESENTATION OF RESULTS Graphs comparing physical/chemical data with total abundance, number of species, diversity and abundance of indicator species are prepared. An example is presented in figure 2 above. Below some additional examples of data presentations of results from the pilot study are presented. One parameter that is affected is the number of species which clearly decreases with increasing organic pollution. Fig 12 and 13 compares the number of species caught during the wet season in October 2003 and during the dry season in June 2003, respectively, at three sites in Sg Sarawak and two in Sg Maong. It is evident that the number of species decreases with decreasing concentration of oxygen, which is a result of the discharge of sewage. 16

21 Number of species mg/l Number mg/l S8 S4 S6 SM2 SM1 3,5 3 2,5 2 1,5 1 0,5 0 Number of species Oxygen in water Figure.12. Number of species of fish and shrimps caught in Sg Sarawak (S8, S4, and S6) and Sg Maong (SM1 and SM 2) in October 2003 (wet season) compared to the concentration of oxygen measured on the sites S8 S4 S6 SM2 SM1 3 2,5 2 1,5 1 0,5 0 Number of species Oxygen in water Figure 13. Number of species of fish and shrimps caught in Sg Sarawak (S8, S4, and S6) and Sg Maong (SM1 and SM 2) in June 2003 (dry season) compared to the concentration of oxygen measured on the sites. 17

22 Number mg/kg In figure 14 the number of species caught is compared to the concentration of NH 4 -N in the sediment, which is another indicator of pollution S8 S4 S6 SM2 SM Number of species NH4-N in sediment Figure 14. Number of species of fish and shrimps caught in Sg Sarawak (S8, S4, and S6) and Sg Maong (SM1 and SM 2) in October 2003 (wet season) compared to the concentrations of NH 4 -N in sediments on the sites. The indicator species composition also changes with increasing organic pollution. The percentage of species that are indicators for organic pollution (cf. Table 1) increase with decreasing concentrations of oxygen (Fig 15). 18

23 % Indicator species mg/l S8 S4 S6 SM2 SM1 4 3,5 3 2,5 2 1,5 1 0,5 0 Abundance pollution indicator species (%) Oxygen in water Figure 15. Abundance of fish that are indicators for organic pollution in percentage of total abundance caught in Sg Sarawak (S8, S4, and S6) and Sg Maong (SM1 and SM 2) in December 2003 compared to the oxygen concentration in water). 6. REFERENCES Atack, K (2006). A Field Guide to the Fishes of Kuching Rivers. Sarawak, Malaysian Borneo. Natural History Publications (Borneo) Kota Kinabalu Brown, L.R. (2000). Fish Communities and Their Associations with Environmental Variables, Lower San Joaquin River Drainage, California. Environmental Biology of Fishes. 57 (3) Stephens, J.S. et al.(1988). Fish Assemblages as Indicators of Environmental Change Near shore Environments. pp In: Soule, D.F. and Keppel, G.S (eds.), Marine Organisms as Indicators. Springer Verlag. Ward et al. (1998). Environmental Indicators for National State of the Environment Reporting Estuaries and the Sea. Environment Australia, part of the Department of the Environment. Commonwealth of Australia