Changes in Algal Plankton Composition and Physico-Chemical Variables in a Shallow Oxbow Lake

Majd Muwafaq Yaqoob,Sándor Alex Nagy,György Dévai,Csaba Berta,István Grigorszky,László József Szabó,Szilárd Szabó,Éva Ács,István Bácsi,Imre Somlyai,János Nagy,Alexandra Simon

doi:10.3390/w13172339

Majd Muwafaq Yaqoob, Sándor Alex Nagy + Show 10 more

Open Access

https://doi.org/10.3390/w13172339

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Abstract

In our work, we sought to answer whether we find differences among the various zones of an oxbow lake with different land uses based on physico-chemical variables and dominant algal plankton species. The two ends of the oxbow lake are bordered by settlements, and near them there are open water areas where fishing is the major utilization form. Between the two open water areas we find a protected area with a large aquatic plant coverage and two transition zones towards the open water areas. The oxbow lake receives periodic water replenishment only at one end from one of the open water areas. During summer—due to the lack of rain—the water of the oxbow lake is used for irrigation in the surrounding arable land, so the water level fluctuation can be significant in the riverbed. Our study was performed within a vegetation period of spring, early summer, mid-summer, and fall. In connection with the ecological classification of a smaller water body, studies on the physical and chemical properties of the water and the composition of the algal plankton are usually carried out in few places and relatively infrequently. The characteristics of a water body are also influenced by seasonal changes, which can be the changes in the extent of vegetation coverage, the way land is used and the possibility of water replenishment, to which the algal community usually responds with changes. Based on our study, it can be said that even in a relatively small water body, we found a large differences based on the chemical and physical properties of the water and the characteristic algal species. Open water zones, areas with large macrovegetation coverage, and the transition zones were separated from each other.

Highlights

All over the world, shallow lakes are considered to be biodiversity hotspots for aquatic wildlife and human demands
TT represents the transitional zone between open water zone of Tiszanagyfalu area (OWT) and the middle zone (M)
During the April sampling period, the between-group Principle component analysis (PCA) calculated on the physico-chemical variables showed that the five zones could be divided into three groups (Figure 2A)

Summary

Introduction

Shallow lakes are considered to be biodiversity hotspots for aquatic wildlife and human demands. Most oxbow lakes can be found in lowlands with densely populated surroundings, which usually involves high risks of degradation [13]. They are critical refugees for maintaining biodiversity, because they provide unique habitats. In the lotic system of the Nagy–Morotva oxbow lake, which receives water from the Tisza River, the irregular dynamics of inflow and the variable flushing rates markedly alter environmental conditions for communities [17]. Phytoplankton response to the changing conditions can be direct through physiology, and indirect by mediating the effects on environmental factors limiting primary productionmost notably light and nutrients [25]. The L represents the left part of transects, the M represents the middle part of transect, and the R represents the right part of transects; these abbreviations apply to all sampling points

Sample Collection

Principal Component Analysis of Physical and Chemical Variables

Principal Componant Analysis of the Algal Plankton

Occurrence of Dominant Algal Species in the Investigated Sampling Times