Assessment of water quality based on diatom indices in a small temperate river system, Kowie River, South Africa

Abstract

This study aimed to assess the impact of land use patterns on water quality and benthic diatom community structure and to test the applicability of diatom indices developed in other regions of the world to a small temperate southern African river system. Sampling was conducted at eight study sites along the length of the river on four separate occasions. Multivariate data analyses were performed on the diatom community dataset to specify the main gradients of floristic variation and to detect and visualize similarities in diatom samples in relation to land-use patterns within the catchment. One hundred and twelve (112) diatom species belonging to 36 genera were recorded during the study. Canonical correspondence analysis (CCA) demonstrated that variations in the benthic diatom community structure were best explained by ammonium, nitrate, conductivity, pH, temperature, resistivity and water flow. OMNIDIA was used for calculation of selected diatom water quality indices. A number of the indices, e.g., the trophic diatom index (TDI), eutrophication/pollution index and biological index of water quality (BIWQ), either under-or over-estimated the water quality of the system. With few exceptions, there were no significant correlations (p> 0.05) between the diatom indices' values and the nutrient variables. The absence of any significant correlations between the diatom indices' values and selected physico-chemical variables suggests that indices developed in other regions of the world may not be suitable for temperate southern African rivers.

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“…The highest diversity and total numbers of epiphytic algae were recorded in the sites 4 and 1, possibly because these sites were surrounded by agriculture areas and grazing activities, rendering that they were vulnerable for the organic pollution as explained in previous studies (33). Lower number of species and biomass was recorded in the Site3, which is likely due to the swimming and fishing activities.…”

The Application of Benthic Diatoms in Water Quality Assessment in Lepenci River Basin, Kosovo

“…evaluation of the ecological status. Anyhow, large number of taxa that can be involved remains a problematic issue in using and analyzing diatoms as an biological indicator [Soltanpour et al 2011, Dalu et al 2016] that has been so far partially solved by using the indices that rely only on genera [Rumeau and Coste 1988, Rovira et al 2012, Blanco et al 2012. Additionally, other authors [Àcs et al 2004 in the biomonitoring studies in Kosovo concerning the water quality issues, the diatom flora has been neglected and has therefore received little attention or no attention at all, even though it is well-known that they, in particular the freshwater species, constitute a major group of algae.…”

Sử Dụng Chỉ Số Tdi (Trophic Diatom Index) Của Thực Vật Phù Du Để Đánh Giá Trạng Thái Dinh Dưỡng Ở Một Số Thủy Vực Trong Thành Phố Bến Tre

“…Nghiên cứu trên sông Nišava, Southeren (Serbia) đã thể hiện mối tương quan thuận và có ý nghĩa thống kê giữa chỉ số TDI và phốt phát, nitrat và ion amoni nhưng sự tương quan đó yếu (Andrejić et al, 2012). Ngược lại, nghiên cứu ở hệ thống sông Kowie (South Africa) đã cho thấy khá rõ mối tương quan của chỉ số TDI với các yếu tố môi trường như pH, độ mặn (Dalu, & Froneman, 2016). Nodine và cộng sự (2014) đã nhận định rằng việc sử dụng quần xã tảo silic để phản ảnh các thông số môi trường trong phạm vi không gian của thủy vực là đáng tin cậy.…”