Study of the Physical and Chemical Characteristics of Lake Tondano, North Sulawesi

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FORMOSA NEWS

Minahasa, North Sulawesi —Study of the Physical and Chemical Characteristics of Lake Tondano, North Sulawesi. This research was conducted by Jefry Jack Mamangkey, Livana Rawung, and Meidy Atina Kuron from Manado State University (UNIMA) in a scientific article published in the International Journal of Scientific Multidisciplinary Research (IJSMR).

Research conducted by Jefry Jack Mamangkey, Livana Rawung, and Meidy Atina Kuron revealed that the physical and chemical conditions of Lake Tondano water are still within the tolerance limit for aquatic organisms, but show indications of environmental pressure due to human activities around the lake, especially from domestic waste, agriculture, and fish farming using floating net cages.

Strategic Lakes with Human Activity Pressure

Lake Tondano is a volcanic lake located in the Minahasa highlands with an area around 4,278 hectares. This lake has an important role for the people of North Sulawesi. In addition to being a source of raw water for regional drinking water companies (PDAM), this lake also supports hydropower generation and becomes a center for freshwater fisheries activities through the system floating net cage.

However, increased human activity around the lake has ecological consequences. Settlements, agricultural activities, and fish farming put pressure on water quality. Domestic waste from households as well as fish feed residues from cages are the main sources of nutrients entering the lake.

The accumulation of nutrients such as nitrogen and phosphorus can trigger Eutrophication, which is a condition when waters become too rich in nutrients so that it triggers the excessive growth of aquatic plants and algae. This phenomenon can reduce the quality of the ecosystem and disturb the biological balance of the lake.

Research Method: Measurements at Five Lake Points

The research was conducted with an Quantitative Descriptive through water sampling in several locations representing different conditions in Lake Tondano. The research team determined Five observation stations, namely:

1. Aquatic vegetation area
2. The middle of the lake as a control area
3. The inlet or river that enters the lake
4. Floating net cage fish farming area
5. Outlet or outlet of the lake

Water sampling is carried out at ambient depths 0.5–1 meter, then analyzed using water quality measuring devices such as DO meters and pH meters. The analyzed parameters include:

1. Water temperature
2. pH or acidity level
3. Dissolved Oxygen (DO)

The data obtained is then compared to the water quality standards set in the Government Regulation of the Republic of Indonesia Number 22 of 2021 concerning Environmental Management.

Research Results: Stable Temperature, Oxygen Pressured in Cultivation Area

The results of the study show that in general, the physical condition of Lake Tondano water is still within the range that can support the life of aquatic organisms.

Some of the study's key findings include:

1. Water temperature: 25.4 – 27.7 °C
2. Water pH: 6.2 – 8.6 (neutral to slightly alkaline)
3. Dissolved oxygen (DO): 4.8 – 8.7 mg/L

This temperature range is still considered ideal for aquatic organisms. This condition also shows that the heat distribution in the lake is relatively even due to the fairly good circulation of water masses.

The pH value which is in the neutral to slightly alkaline range also indicates that the waters are still quite chemically stable. These conditions support the physiological processes of fish and other aquatic organisms.

Nevertheless, researchers found indications of environmental pressure, especially in Floating net cage fish farming area. At these locations, dissolved oxygen levels reached the lowest value, namely 4.8 mg/L, close to the minimum limit required for fish life. This decrease in oxygen is strongly suspected to be triggered by decomposition of fish feed residues and organic waste, which consumes large amounts of oxygen during the decomposition process.

Water Quality Status: Light to Moderate Polluted

Based on the analysis Pollution Index, the water conditions of Lake Tondano are categorized as light to moderate pollution.

Areas with higher pollution levels are generally around:

1. Residential areas
2. Floating net cage area
3. The location of the river flow from the mainland

The ever-increasing accumulation of organic waste and nutrients has the potential to exceed the lake's natural ability to decompose pollutants. If this condition is left unchecked, the lake is at risk of siltation faster due to sedimentation and growth of aquatic plants such as Hyacinth.

Ecological Impacts and Future Threats

The decline in lake water quality not only has an impact on the ecosystem, but also on the economic activities of the community. If oxygen levels continue to drop, the risk Mass Mortality of Farmed Fish can be increased. In addition, excessive growth of aquatic plants can cover the surface of the lake and inhibit the penetration of sunlight into the water.

In the long term, these conditions can interfere with the strategic function of Lake Tondano as:

1. Source of clean water
2. Electrical energy source
3. Fishing area
4. Biodiversity Ecosystem

Research Recommendation: Integrated Lake Management

Researchers from Manado State University emphasized the importance of Integrated and sustainable management to maintain the health of the lake ecosystem.

Some recommended steps include:

1. Control of domestic waste from settlements around the lake.
2. Regulating the number of floating net cages so that they do not exceed the carrying capacity of the waters.
3. Reduction of the use of chemical fertilizers on agricultural land around water catchment areas.
4. Regular monitoring of water quality to detect environmental changes early.

A collaborative approach between the government, the community, and the academic sector is considered important to maintain the sustainability of Lake Tondano.

 

Author profile

1.       Jefry Jack Mamangkey – Manado State University.

2.       Livana Rawung – Manado State University.

3.       Meidy Atina Kuron – Manado State University.

Research source

Mamangkey, J. J., Rawung, L., & Kuron, M. A. (2022).

International Journal of Scientific Multidisciplinary Research (IJSMR)

DOI: https://doi.org/10.55927/ijsmr.v4i2.6
Official URL: https://journalijsmr.my.id/index.php/ijsmr