Recently, many reservoirs have been built in the Special Region of Yogyakarta in several areas, both in Bantul and its surroundings. Some of the reservoirs that have been built are new and some are old. In addition, in the construction of the reservoir, some use tarpaulin and some use cement. The impact of the construction of reservoirs in different ways and times will have different ecosystem impacts. This phenomenon is the reason for the interest of the UNY research team led by Drs. Sudarsono, M.Si. to determine differences in environmental balance seen from primary productivity, abundance of plankton, diversity index, dominance index, and saprobic index in Potorono and Imogiri. The team led by Drs. Sudarsono, M.Si. are consisting of Dra. Ratnawati, M.Sc. as plant morphology and anatomy expert, Dra. Budiwati, M.Si. as a botanist, and 3 students from the biology study program, namely Dwi Rahmawati, Tri Purwa Ningrum and Muhammad Dzikron Amien. This research conducted between February and July 2021.

Potorono reservoir is located in Potorono Village, Banguntapan, Bantul. The reservoir began to be built in 2017 through the Telaga Desa program. It has an area of ​​4800 square meters which was built on an area of ​​30,000 square meters of wanadesa land. The construction of the reservoir is specifically used to accommodate the overflow of rainwater from the Mruwe River and the nearby Tambak baya. While the Imogiri reservoir is located in Wukirsari Village, Imogiri, Bantul. Imogiri reservoir began to be built in 2020 with a pool area of ​​2500 square meters. The  benefit of the construction of reservoir in Imogiri is for flood retention, because during the rainy season the water of the Celeng river often overflows and it is hoped that the water stored in the reservoir will not overflow into the area around the reservoir and the highway. With the existence of the reservoir, it is also expected that it can be useful as land conservation and water conservation, so that the surrounding ground water level rises and is beneficial for the community. In addition, it can become a new tourist location so that it can help improve the economy of local residents

 Judging from the year of construction, the Potorono Reservoir is one of the old ecosystems, while the Imogiri Reservoir is a new ecosystem. There is a difference in the year of manufacture in the two reservoirs, it is possible that it can cause differences in the environmental balance. One of the organisms that live in aquatic ecosystems and is very influential on environmental conditions is plankton. Plankton can provide information about water conditions through biological parameters.

Based on the results of research in the two reservoirs, Potorono has a plankton abundance value of 1,055.30 individuals/Liter while the Imogiri has a plankton abundance value of 2,084.4 individuals/Liter. The plankton diversity index value in Potorono ranged from  2,50 - 3,03 (medium) and the plankton diversity index value in Imogiri ranged from 2.26 to 2.50 (medium). (Lak)