- Email: [email protected]
Biomonitoring Validation
A P P E N D I X
E Biomonitoring Validation
A plastic strainer with a diameter of 20 25 cm and 1 mm mesh size and tweezers are used for directly collecting macroinvertebrates. The strainer should be used as follows: • To collect organisms living in the water column or close to the river bank, as well as those living on submerged vegetation, by pulling the strainer through the water. • The strainer should be held behind or underneath rocks or other substrates while they are lifted; organisms can also be removed by hand from lifted substrates and caught with the strainer while drifting. • Ground substrate can be kicked with the heels and the strainer used for sifting through the current with the separated material. • Leaf packs should be placed inside the strainer and searched with tweezers for macroinvertebrates. Tweezers should be used mainly when macroinvertebrates live tightly attached to the substrate. The average strainer “emptying rate” is after each pass, up to three passes in the case of rock-lifting. Total sampling time is divided approximately 50% using strainer and 50% using tweezers. For sampling the river usually has to be crossed. Collection starts at one side and continues until the other side is reached (for rivers with a depth of 1 m and a breadth of up to 15 m; if deeper than 1 m or broader than 15 m, then a boat and a strainer attached to a pole are usually needed). The river is usually crossed back by the collecting person some meters further upstream (zigzag direction) toward the original starting site. The main criterion for this semiquantitative collection method is time; there are no defined sampling areas. All types of microhabitats present at a particular site have to be equally examined for macroinvertebrates. Collected organisms should be fixed immediately in 70% ethanol at the time of sampling. At the beginning of collecting at each study site, a presampling has to be carried out, consisting of subsamples taken every 30 min in order to establish a representative sampling time. From the results obtained an accumulated taxa curve should be elaborated. In the example (Fig. E.1), 120 min were determined as a representative sampling time (second stable point). Under ideal conditions a weekly sampling strategy is recommended; if time and money are limiting factors, then a monthly sample, taken always at the same day and time (sampling is recommended to take place during early morning and under normal current situations; during high water or flooding macroinvertebrates will hide in order to escape being carried away by the strong currents). The strainer method presented here has been suggested by the Government of Costa Rica (other techniques using D-nets or kick-nets can also be calibrated) under a biomonitoring law proposal (Anon., 2005). This method is coupled to the use of a modified BMWP (Biological Monitoring Working Party) index for Costa Rica, and originally developed in the year 1970 in England as a quick, easy, and cheap method for evaluating water quality using macroinvertebrates as bioindicators. The index is used to define different levels of water quality (Table E.1), based on identification of organisms to family level. Each family is assigned a sensitivity value ranging from 1 to 10 (Fig. E.2), reflecting tolerance to pollution based on the knowledge of distribution and abundance. The values for each family are then summed up
293
294
APPENDIX E
30
Accumulated number of taxa
25 20 15 10 5 0 0
20
40
100 60 80 Time of sampling (min)
120
140
FIGURE E.1 Accumulated number of taxa curve of aquatic macroinvertebrates in a presampling campaign (December 2004) at the Dos Novillos River, Gua´cimo, Limo´n, Costa Rica. Source: Taken from Stein, H., Springer, M., Kohlmann, B., 2008. Comparison of two sampling methods for biomonitoring using aquatic macroinvertebrates in the Dos Novillos River, Costa Rica. Ecol. Eng. 34, 267 275 (Stein et al. 2008). TABLE E.1 Categories of Water Quality as Defined by the Numerical Values of the Biological Monitoring Working Party (BMWP) Index and Their Color Equivalents for Mapping Purposes Water quality
BMWP
Color
Excellent
.120
Light blue
Good: no pollution or obvious distortions
101 120
Dark blue
Regular: eutrophic, medium pollution
61 100
Green
Bad: polluted
36 60
Yellow
Bad: very polluted
16 35
Orange
Very bad: extremely polluted
,15
Red
FIGURE E.2 Field guide with some macroinvertebrate families as bioindicators of excellent to good water quality and their associated Biological Monitoring Working Party sensitivity numbers, modified for Costa Rica.
APPENDIX E
295
independently from abundance and generic or species diversity. Sensitivity scores higher than 120 points indicate undisturbed aquatic ecosystems, while low values indicate serious contamination (mostly organic) of the environment.
References Anon., 2005. Ley del Recurso Hı´drico No. 14.585. Available from: ,https://www.ministeriodesalud.go.cr/sobre_ministerio/do/productos/ V_Cont_Abr09_Nov09/Informe%20final%20V%20etapa-2/Proyectos%20adicionales/Anexo%202%20Productos/Anexo%202.A%20productos/Anexo%202.A.4/Base%20Datos%20ambito%20Agua/Marco%20Legal/Proyecto%20Ley/LEY%20%20REC%20Hidrico%2014.585.pdf.. Stein, H., Springer, M., Kohlmann, B., 2008. Comparison of two sampling methods for biomonitoring using aquatic macroinvertebrates in the Dos Novillos River, Costa Rica. Ecol. Eng. 34, 267 275.
E Biomonitoring Validation
A plastic strainer with a diameter of 20 25 cm and 1 mm mesh size and tweezers are used for directly collecting macroinvertebrates. The strainer should be used as follows: • To collect organisms living in the water column or close to the river bank, as well as those living on submerged vegetation, by pulling the strainer through the water. • The strainer should be held behind or underneath rocks or other substrates while they are lifted; organisms can also be removed by hand from lifted substrates and caught with the strainer while drifting. • Ground substrate can be kicked with the heels and the strainer used for sifting through the current with the separated material. • Leaf packs should be placed inside the strainer and searched with tweezers for macroinvertebrates. Tweezers should be used mainly when macroinvertebrates live tightly attached to the substrate. The average strainer “emptying rate” is after each pass, up to three passes in the case of rock-lifting. Total sampling time is divided approximately 50% using strainer and 50% using tweezers. For sampling the river usually has to be crossed. Collection starts at one side and continues until the other side is reached (for rivers with a depth of 1 m and a breadth of up to 15 m; if deeper than 1 m or broader than 15 m, then a boat and a strainer attached to a pole are usually needed). The river is usually crossed back by the collecting person some meters further upstream (zigzag direction) toward the original starting site. The main criterion for this semiquantitative collection method is time; there are no defined sampling areas. All types of microhabitats present at a particular site have to be equally examined for macroinvertebrates. Collected organisms should be fixed immediately in 70% ethanol at the time of sampling. At the beginning of collecting at each study site, a presampling has to be carried out, consisting of subsamples taken every 30 min in order to establish a representative sampling time. From the results obtained an accumulated taxa curve should be elaborated. In the example (Fig. E.1), 120 min were determined as a representative sampling time (second stable point). Under ideal conditions a weekly sampling strategy is recommended; if time and money are limiting factors, then a monthly sample, taken always at the same day and time (sampling is recommended to take place during early morning and under normal current situations; during high water or flooding macroinvertebrates will hide in order to escape being carried away by the strong currents). The strainer method presented here has been suggested by the Government of Costa Rica (other techniques using D-nets or kick-nets can also be calibrated) under a biomonitoring law proposal (Anon., 2005). This method is coupled to the use of a modified BMWP (Biological Monitoring Working Party) index for Costa Rica, and originally developed in the year 1970 in England as a quick, easy, and cheap method for evaluating water quality using macroinvertebrates as bioindicators. The index is used to define different levels of water quality (Table E.1), based on identification of organisms to family level. Each family is assigned a sensitivity value ranging from 1 to 10 (Fig. E.2), reflecting tolerance to pollution based on the knowledge of distribution and abundance. The values for each family are then summed up
293
294
APPENDIX E
30
Accumulated number of taxa
25 20 15 10 5 0 0
20
40
100 60 80 Time of sampling (min)
120
140
FIGURE E.1 Accumulated number of taxa curve of aquatic macroinvertebrates in a presampling campaign (December 2004) at the Dos Novillos River, Gua´cimo, Limo´n, Costa Rica. Source: Taken from Stein, H., Springer, M., Kohlmann, B., 2008. Comparison of two sampling methods for biomonitoring using aquatic macroinvertebrates in the Dos Novillos River, Costa Rica. Ecol. Eng. 34, 267 275 (Stein et al. 2008). TABLE E.1 Categories of Water Quality as Defined by the Numerical Values of the Biological Monitoring Working Party (BMWP) Index and Their Color Equivalents for Mapping Purposes Water quality
BMWP
Color
Excellent
.120
Light blue
Good: no pollution or obvious distortions
101 120
Dark blue
Regular: eutrophic, medium pollution
61 100
Green
Bad: polluted
36 60
Yellow
Bad: very polluted
16 35
Orange
Very bad: extremely polluted
,15
Red
FIGURE E.2 Field guide with some macroinvertebrate families as bioindicators of excellent to good water quality and their associated Biological Monitoring Working Party sensitivity numbers, modified for Costa Rica.
APPENDIX E
295
independently from abundance and generic or species diversity. Sensitivity scores higher than 120 points indicate undisturbed aquatic ecosystems, while low values indicate serious contamination (mostly organic) of the environment.
References Anon., 2005. Ley del Recurso Hı´drico No. 14.585. Available from: ,https://www.ministeriodesalud.go.cr/sobre_ministerio/do/productos/ V_Cont_Abr09_Nov09/Informe%20final%20V%20etapa-2/Proyectos%20adicionales/Anexo%202%20Productos/Anexo%202.A%20productos/Anexo%202.A.4/Base%20Datos%20ambito%20Agua/Marco%20Legal/Proyecto%20Ley/LEY%20%20REC%20Hidrico%2014.585.pdf.. Stein, H., Springer, M., Kohlmann, B., 2008. Comparison of two sampling methods for biomonitoring using aquatic macroinvertebrates in the Dos Novillos River, Costa Rica. Ecol. Eng. 34, 267 275.