Environmental controls of plankton community dynamics in a sub-tropical river system of Bangladesh

Surma River of Bangladesh is a representative of sub-tropical river system which is complex, dynamic and interacting socio-ecological system. Though land-based activities control the water quality of this river system, no studies have been conducted on the role of land-use patterns on water quality and biotic communities. Therefore, this study aimed to understand the impacts of water quality on the plankton community dynamics of Surma River basin. In addition, the study also examined the impacts of land-use patterns on water quality of river. Land-use patterns were identified by analyzing Landsat-8 imageries of the United State Geological Survey. Data on biotic and abiotic variables were collected from 15 sampling stations during dry season. Unsupervised and supervised classification techniques were used to identify the land-use patterns. Weighted arithmetic method was used to develop water quality index of river system. This study found four types of land-use patterns around Surma River basin (i.e., built-up area, barren land, river, vegetation and agriculture). Water quality index indicates that water quality is good in the rural area, while bad in the urban areas. Our study found that land-use pattern is a good predictor of water quality ( R 2 = 0.97) of Surma River basin. Our study also found that high plankton species diversity coincides with the good water quality of the river. This study will serve as tool for the management of Surma River basin of Bangladesh.