UNAIR NEWS – Reservoirs are tapering bodies of water created by river dams. Generally, reservoirs have an elongated shape to follow the riverbed currents. Bajulmati Reservoir is one of the reservoirs that functions as an irrigation reservoir. However, there is no information regarding the condition of these waters, especially the fertility of the waters in the Bajulmati Reservoir.
In this regard, one of the lecturers from Universitas Airlangga (UNAIR) Suciyono S.St.Pi., MP, tried to review the productivity of Bajulmati reservoir water based on the abundance of phytoplankton. Reporting from a popular scientific article entitled “Assessment of Seasonal Waters Quality Based on Abundance, Diversity, and Domination of Phytoplankton in Bajulmati Reservoir”, Suciyono explained that in determining the fertility of waters, there are several water quality assessments that can be carried out including aspects of physics, chemistry and biology.
“Measurement of temperature, transparency, and dissolved oxygen is carried out directly (in situ). Meanwhile, nitrogen and phosphate measurements are carried out in the laboratory, by taking a 250 ml water sample and storing it in a cool box, “he explained.
The research method, he continued, was using purposive sampling method with four sampling points from the entire reservoir area. The results showed that phytoplankton were nine genera, consisting of 5 genera from the Cyanophyceae Class, and one genus from each class, Chlorophyceae, Bacillariophyceae Class, Euglenophyceae, and Dinophyceae. The productivity of Bajulmati Reservoir waters is included in the eutrophic category. Meanwhile, the diversity index shows a stable distribution of individuals and a low community.
“The highest phytoplankton abundance was found in the two sampling sites which were classified as eutrophic. The difference in phytoplankton abundance in each place is caused by differences in nutrient content. The abundance of phytoplankton is directly proportional to the nitrogen content,” he said.
Furthermore, Suciyono explained that the low diversity index is assumed to be caused by an increase in water turbidity due to rainwater flow. The increasing turbidity causes a decrease in the penetration of sunlight which affects the photosynthesis process.
“In fact, each phytoplankton genus has a different response, especially to the nutrient ratio of nitrogen and phosphorus, in water bodies,” he said.
At the end, Suciyono explained that Bajulmati Reservoir has a high abundance of phytoplankton. Therefore, he said, Bajulmati Reservoir is included in the eutrophic category with nine genera.
“In addition, Bajulmati Reservoir has a stable individual distribution. Genus Cyanophyceae is the dominant class in these waters,” he concluded.
Author: Ananda Wildhan Wahyu Pratama
Editor: Nuri Hermawan
