Vol.:(0123456789) 1 3 Community Ecology https://doi.org/10.1007/s42974-020-00015-6 ORIGINAL ARTICLE Multivariate approaches to determine the relationship between fsh assemblage structure and environmental variables in Karatoya River, Bangladesh Most. Mahmuda Akhi 1  · Md. Abu Sayed Jewel 1  · Md. Ayenuddin Haque 1  · Biplob Kumer Sarker 1  · Mst. Samsad Khatun 1  · Alok Kumar Paul 1  · M. Shahanul Islam 2  · Simon Kumar Das 3,4 Received: 17 January 2020 / Accepted: 3 June 2020 © Akadémiai Kiadó Zrt. 2020 Abstract Karatoya River is an important freshwater system that is home to diferent types of fsh species. In the present study, the seasonal abundance and diversity indices of fsh assemblage and their relationship with physicochemical parameters were studied. Fifty-four fsh species were recorded from four stations for 12 months. The highest number of fsh was recorded during the post-monsoon season and the lowest was recorded in the monsoon season. Analysis of similarity evidenced a sig- nifcant diference (P < 0.05) in species abundance among the seasons. Similarity percentage analysis showed that the overall average dissimilarity among the three seasons was 73.53%, and six species were responsible for this dissimilarity. Non-metric multidimensional scaling ordination plot based on similarity indicated that the monsoon season completely difered from the other two seasons (pre-monsoon and post-monsoon) in terms of fsh abundance. The values of Shannon–Wiener diversity, Margalef’s richness, and Pielou’s evenness indices varied from season to season. Canonical correspondence analysis was used to identify the most important water quality parameters infuencing the seasonal variation of fsh assemblage structure and to reveal the remarkable roles of alkalinity, total dissolved solids, electrical conductivity, and dissolved oxygen in the Karatoya River in Bangladesh. This study provides essential baseline information on the relationship between the environ- mental parameters and fsh diversity in freshwater habitats in Bangladesh. Keywords Environmental variables · Fish assemblage · Seasonal variation · Diversity indices · Canonical correspondence analysis · Freshwater ecosystem Introduction Bangladesh constitutes about 800 rivers with a total length of 24,140 km (Banglapedia 2012; DoF 2013), indicating the country’s great fshery potential; its fsh biodiversity ranked third in Asia (Hussain and Mazid 2001). The diferent types of freshwater bodies in Bangladesh are home to 265 fresh- water fsh species (Rahman 2005). However, over the past few years, fsh diversity from natural habitats in Bangladesh gradually decreased. Scientists found specifc problems, such as overfshing, the use of destructive fshing gear, pol- lution, and development activities, as the main degrading factors of the fshery status of the riverine ecosystem (Sham- suzzaman et al. 2017; Ali et al. 2014; Hussain 2010). The degradation of riverine ecosystem destroys the structure and function of riverine biota (Alam et al. 2013). Consequently, numerous fsh species have become vulner- able, endangered, or critically endangered. Bangladesh’s * Simon Kumar Das simon@ukm.edu.my; skdas_maa@yahoo.com 1 Department of Fisheries, Faculty of Agriculture, University of Rajshahi, Rajshahi 6205, Bangladesh 2 Faculty of Food Engineering and Biotechnology, Tianjin University of Science and Technology, No 29, 13th Avenue, TEDA, Tianjin, China 3 Department of Earth Sciences and Environment, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, D.E., Malaysia 4 Marine Ecosystem Research Centre, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi, Malaysia