The river health of Alista River based on macroinvertebrates communities at Selorejo Village Dau Subdistrict Malang Regency

The Alista River is one of the rivers in the upstream Brantas watershed which has relatively natural conditions, but currently there are agricultural activities on the riverbank. The aim of this study was to analyze the health status in Alista River based on the macroinvertebrate communities. This study uses a survey method. Sampling was carried out at 5 stations based on different land use. Sampling of macroinvertebrates used the kicking technique with a hand net with a mesh size of 500 μm in a 10 meter long riffle area. Data analysis used the value of BMWP index (Biological Monitoring Working Party) and the ASPT (Average Score Per Taxon). The results of the identification of macroinvertebrates found were 38 families for instance Glossossomatidae, Lepidosmatidae, and Richardsonianidae. The families belong to 10 orders and 3 classes. The lowest family is 11 families at station 5 (citrus and bamboo gardens). The highest families are 29 families at station 3 (citrus gardens and forests). The results show BMWP-ASPT score ranged from 6.3–4.3 indicating excellent to moderately poor health status. Stations with excellent categories, namely stations 1,2,3,4. Station land use 1,2,3 secondary forest before tourism was discovered including Glossosomatidae. Station 4′s land use is in the form of a tourism location and Lumbriculidae has been found. Stations in the moderately poor category, namely station 5 which is located after tourism sites (citrus gardens and settlements) were found Richardsonianidae.


Introduction
A river basin is a topographical area where water flows from land areas to river systems flowing towards estuaries [1].The current condition of watersheds has been damaged [2], one of which is the upstream Brantas watershed [3].Rivers are the aquatic part of a watershed.River ecosystems have flow properties that flow in one direction from upstream to downstream [4].Based on its trophic characteristics, the dominant biota that live in river ecosystems are heterotrophic organisms, meaning they cannot make their own food, namely benthic macroinvertebrates.The biological approach is generally complementary to the physical and chemical approach to water.Various aquatic biota can be used to monitor river water conditions, for example fish, benthic algae and macroinvertebrates [5].[6].
Macroinvertebrates are invertebrates that are confined to mesh sizes >200 to 500 µm [7], [8].Abundant invertebrates in upstream river ecosystems are dominated by 95 percent insect larvae and nymphs [9], [10].Macroinvertebrates are the biota most often used to monitor the health of river water 1328 (2024) 012008 IOP Publishing doi:10.1088/1755-1315/1328/1/012008 2 quality [11], [12], [13] because they live relatively sedentary at the bottom of the water, have a long life cycle and taking samples is relatively easy [14], [15].The problem of environmental damage that occurs in Indonesia has become the concern of many parties.The frequent occurrence of natural disasters such as landslides, floods and droughts is an indication that environmental damage has occurred.The reduction in the carrying capacity of river basins is thought to be the main cause of environmental damage which is getting worse from year to year.
The Alista River is one of the rivers in the upper Brantas watershed that is still found in relatively natural conditions.Macroinvertebrate profile conditions in rivers in the upper Brantas watershed are generally found to be tolerant, as found by Richardsonianidae [3].Based on observations during a survey on the Alista River on October 12 2022, it appears that the condition of the river is already being used for tourism with land clearing for tourism becoming wider and wider for camping areas.The land use upstream of the Alista River includes a garden area for orange picking tourism.This can cause the quality of the Alista River waters to decline due to the use of pesticides in orange groves.Based on the results of a survey on April 15 2023, it was found that in the upper reaches of the Alista River there were agricultural activities on the riverbanks which caused landslides, even though there were still natural areas found upstream.Even though the Alista River is used as a water source for agricultural activities.
Based on the description above, the research team wants to conduct research on the health status of the Alista River based on macroinvertebrates in Sekorejo Village, Dau District, Malang Regency and it is hoped that the output of this research can become a biological guidance document for bioassessment of the Alista River to be submitted to the Selorejo Village Government.The aim of this research is to analyze the health status of the Alista River biologically using macroinvertebrates.

Material & Method
The stage that will be carried out in this research is a macroinvertebrate community data base representing the reference area for bioassessment instructions for the Alista River.Before conducting research, the sampling areas or stations must first be determined by looking at the location and condition of the river to facilitate the sampling mechanism [5], [16], by conducting a survey on April 15 2023.Sampling was carried out on the Alista River in Selorejo Village, Dau District, Malang Regency.Taking macorinvertebrate is enough to do once because they have a long life cycle [17].Determination of stations based on land use along the river.The location of the sampling station when presented on a map looks like in Figure 1.Sampling is used to obtain a variety of different species.The tool used is a hand net with a kicking technique [5], [18].The use of hand nets for sampling macroinvertebrates is generally used in shallow water with a total length of 10 m in the riffle area [5], [19], [20].
The data analysis carried out in this research was to carry out calculations using the BMWP-ASPT Index.The Biological Monitoring Working Party (BMWP) determines the number of family indicators in the sample.BMWP assigns a pollution tolerance score between 1 and 10 to all indicator organisms at the family level.The greater the tolerance of organisms to pollution, the lower their BMWP values.Individual scores are then tabulated to obtain a total BMWP score [21], [22], [23], [24].Water quality assessments are generally related to ASPT scores listed in Table 1.ASPT scores were calculated for each macroinvertebrate sample taken from each research location.

ASPT Formula =
Total BMWP indes score Number of families found and have a score (1) Table 1.Average Score Per Taxon (ASPT)

Figure 2. Alista River Macroinvertebrate Composition
The lowest number of families was at station 5, namely 10 families (see Figure 2), including Richardsonianidae, Chironomidae, Simuliidae, Baetidae, Planorbidae, Lumbriculidae, Glossosomatidae, Hydropsychidae, Lepidostomatidae, and Planaridae.The land use is in the form of orange groves and bamboo, the basic substrate is large rocks, stones, gravel and fine sand.Simuliidae inhabit a variety of lotic habitats where they are abundant on rocks, submerged wood, or vegetation in fast to slow currents.Simuliidae has an adaptation pattern to fast currents.The existence of Simuliidae is in fast currents because they have an adaptation pattern to fast currents [25], [26].Simuliidae larvae attach to rocks in fast currents using their heads equipped with hair-like fringes [27].
The highest number of families was at station 3, namely 29 families (see Figure 2), including Glossosomatidae, Limnephilidae, Lepidostomatidae, Leptoceridae, and Polycentropodidae.Land use consists of primary forest and orange groves.The basic substrate of station 3 is large rocks, stones, gravel and sand.Glossosomatidae, Limnephilidae, Lepidostomatidae, Leptoceridae, and Polycentropodidae are part of the order Trichoptera.Habitat for Trichoptera larvae is generally shallow rivers with sow to fast flow, and substrates of rock, gravel, sand, mud, rubbish or aquatic plants.This shows that this station is a suitable habitat for Trichoptera larvae.The existence of Trichoptera larvae is found in fast currents and hard substrate types because this type has an adaptation pattern that can survive in fast current conditions, such as the Glossosomatidae [28], [29].
Based on analysis using the BMWP-ASPT index, the classification results based on macroinvertebrates in the Alista River, Selorejo Village, Malang Regency, obtained from grouping 5 observation stations are presented in Table 2.The results of calculating the Alista River BMWP-ASPT index are classified as excellent to moderately poor water quality (see Table 2).The ASPT score for station 1 is 6.1 in the excellent category.The families that make up station 1 include Hydropsychidae, Perlidae, Lepidostomatidae, Glossosomatidae, Blephariceridae, Limnephilidae, Philopotamidae, Baetidae, and Planaridae.Station 1 is a natural area with land use in the form of primary forest.Glossosomatidae are often found at station 1 because there is food and habitat suitable for their life.Glossosomatidae are scapers or eaters of benthic algae and fine particulate organic matter [30], [31].Glossosomatidae live attached to large rock substrates (clingers) so they are often found at station 1. Station 1 has clean river conditions with the discovery of sensitive macroinvertebrates such as Glossosomatidae.
The ASPT score for station 2 is 6.4 in the excellent category.The families found at station 2 include Glossosomatidae, Lepidostomatidae, Limnephilidae, Perlidae, and Philopotamidae.Station 2 has primary forest and coffee plantation land use.Glossosomatidae was found at station 2 because it has a substrate suitable to its habitat.Glossosomatidae have bodies covered with rocks as a form of adaptation to life in fast currents.The stones that cover the body function as protection and slow down its movement, making it easier to catch food [32].
The ASPT score for station 3 is 6.2 in the excellent category.The families found at station 3 include Glossosomatidae, Lepidostomatidae, Limnephilidae, Leptoceridae, and Perlidae.Station 3 has primary forest and orange grove land use.Glossosomatidae was found at station 3 because it has an environment that is suitable for its habitat.Likewise, the Limnephelidae are sensitive and are found at station 3. Limnephilidae are found in mountainous areas and live as shredders (eaters of litter detritus or coarse organic material) [33], [34].The presence of Glossosomatidae and Limnephilidae at station 3 may indicate that station 3 is still in clean condition with the discovery of sensitive macroinvertebrates.
The ASPT score for station 4 is 6.2 in the excellent category.The families found at station 4 include Glossosomatidae, Lepidostomatidae, Perlidae, Leptoceridae, and Lumbriculiidae.The land use of station 4 is a tourism area with shaded vegetation consisting of trees and dominated by grass.
Glossosomatidae and Lepidostomatidae were found at station 4 because the conditions at station 4 were suitable for their habitat.Glossosomatidae and Lepidostomatidae live on rock and gravel substrates.Trichoptera larvae have different life habits from crawlers, active swimmers, to forming casings.Glossosomatidae have casings in the form of small rocks which function to protect themselves and live attached to large rocks.The presence of sensitive macroinvertebrates such as Glossosomatidae and Lepidostomatidae shows that station 4 is actually in a clean condition [33].However, Lumbriculiidae was found which is an indicator of dirty waters.Lumbriculiidae live on smooth substrates and have external gills that can help supply oxygen to the body [35].The presence of Lumbriculiidae at station 4 indicates that there has been smoothering (stone covered in mud) on the substrate, it is thought that erosion has occurred in the upper area which resulted in the carrying away of smooth substrate that adheres to the stone substrate at station 4. The results of the analysis show that station 4 has experienced damage and warning for the above agricultural activities.
The ASPT score for station 5 is 4.3 in moderately poor category.The families that make up station 5 include Glossosomatidae, Lepidostomatidae, Planorbidae, Lumbriculidae, and Richardsonianidae.The land use of station 5 is an orange grove area with a substrate of large stones, rocks, gravel and fine sand.The low ASPT value at station 5 is supported by the discovery of Lumbriculidae and Richardsonianidae at station 5. Leeches are often found on smooth substrates, while at station 5 the substrate consists of large rocks, stones, gravel and sand.Station 5 has experienced smoothing or the rock substrate has been covered with mud.This is thought to be due to agricultural activities carried out at the top, resulting in erosion and mud runoff entering the river.Richardsonianidae is an indicator of heavily polluted waters.Based on the results of the analysis, station 5 has experienced damage with the discovery of Lumbriculiidae and Richardsonianidae as macroinvertebrates that are tolerant of dirty environments [5].

Conclusion
Based on the results of the observations made, the following conclusions were obtained.There are 38 families of macroinvertebrates found in the Alista River, Selorejo Village, Dau District, members of 10 orders (Trichoptera, Diptera, Coleoptera, Ephemeroptera, Plecoptera, Odonata, Tricladida, Haplotaxida, Arhynchobdellida and Lepidoptera) and 3 classes (Amphipoda, Gastropoda and Oligochaeta).The lowest family is at station 5, namely 10 families, while the highest family is at station 3, namely 29 families.
The results of the BMWP Index analysis obtained a classification of the health of the Alista River in Selorejo Village based on scores from macroinvertebrates at all stations, obtaining ASPT values ranging from 6.4-4.3 which were classified as excellent to moderately poor water quality.Stations 1,2,3,4 ASPT values are 6.1 respectively; 6.4; 6.2; 6.2 with very good water category and station 5 with an ASPT score of 4.3 in the moderately poor health status.The ASPT score for station 4 (tourism land use) was 6.2 in the excellent category but Lumbriculidae was found to be tolerant of heavily polluted waters.Station 5 (land use for orange and bamboo plantations) with an ASPT value of 4.3 in the moderately poor water quality was found in the Lumbriculidae and Richardsonianidae families.This shows that the presence of this family is an indication of damage to stations 4 and 5 so that it becomes a warning for human activity around the Alista River.Based on the results research is recommended to suggestions that can be given to provide protection for macroinvertebrate habitats.

[ 1 ]
Minister of Forestry Regulation Number 22 of 2021 concerning Implementation of Environmental Protection and Management [2] Pambudi AS 2019 The Indonesian Journal of Development Planning 3 [3] Sudaryanti S 2020 Macroinvertebrates for management planning indicators for the Brantas River sub-region upstream of the Batu City area Dissertation [4] Moore JW 2015 J. Fish Aquatic 72 1-11 [5] Sudaryanti S 2021 Benthic Macroinvertebrates for Bioassessment of River Water Health p 147

Table 2 .
Alista River Grouping Based on the BMWP-ASPT Index