Distribution of niche spaces over different homogeneous river sections at seasonal resolution

Abstract

Planktic algae have an essential role in the food web as primary producers; the determination of the ecological niche space occupied by them is thus essential in strategies aimed at sustaining the biodiversity of surface waters. In the present study, principal component analysis combined with the outlying mean index was applied to 14 water quality time series (1993-2005) derived from three previously determined homogeneous sections of the Hungarian part of the River Tisza. As a result, the seasonal distribution of the ecological n-dimensional hypervolumes was determined for the different river sections. In the first upper section, the seasonal niches overlay each other, and no clear separation could be detected. In the middle-and lower reaches, however, a clear separation between the seasons was observed. The identification of these separate niches of the various seasons as the main indicators/drivers of certain ecological communities (e.g. phytoplankton) proved possible.

Estimation of dissolved oxygen in riverine ecosystems: Comparison of differently optimized neural networks

“…2 aA). This is therefore suspected to be a result of the decreased flow velocity of the river ( Hatvani et al, 2018 ); this has also been seen in other rivers ( Cox, 2003 ).…”

“…A2). It was observed that the average runoff of the river quadruples from Tiszabecs (entry point of the river into the country) to Tiszasziget (the last sampling site in Hungary), while it has also been observed that the flow velocity decreases parallel to this ( Hatvani et al, 2018;EC, 2015). Heading downstream, the pH of the river can be considered quasi constant, while EC increased by 50% (Table 1).…”

“…It can be concluded that DO-estimation is more effective on the lower sections of the river, due to the smaller degree of variability in water quality parameters at the distinct sites (Table 1), or even between them (Table 4). This is attributed to the lower velocity and increased runoff of the river (Table 1; Hatvani et al, 2018;EC, 2015).…”

Transverse distribution of cyanobacteria in a regulated urban river

“…For instance, Hillebrand et al (2018) analysed seasonal variations, interdependent patterns, and temporal trends of phytoplankton in the River Elbe over the past 50 years. In terms of seasonal changes, Hatvani et al (2019) more scientifically applied principal component analysis combined with the outlying mean index, finding a clear separation between the seasons. Duan and Bianchi (2006) discussed seasonal variation and the relationship of chl‐a, total suspended solids, nutrients, and chromophoric dissolved organic matter in the lower Mississippi and Pearl Rivers (U.S.).…”