Trend Analysis in Ecological Status and Macrophytic Characterization of Watercourses: Case of the Semois-Chiers Basin, Belgium Wallonia

Abstract

In order to analyze the distribution and evolution of the aquatic vegetation and ecological status of the Semois-Chiers basin (Semois sub-basin and Chiers sub-basin), macrophyte surveys were conducted at 48 sites in 2007 and 2013. Environmental parameters were also measured in order to characterize the waterbodies in terms of physico-chemical properties and anthropogenic pressure. The two-way clustering and indicator value (INDVAL) methods were used to assess groups of sites according to their macrophytic composition and species communities. The results showed a clear difference between streams in the Lorraine area (calcareous watercourses) and in the Ardennes (siliceous). Within each natural region, those with natural vegetation of high ecological status were separated from those dominated by resistant species. The Macrophytical Biological Index for Rivers (IBMR) was calculated for the sites visited in 2010 and 2013 and the results show a trend towards an increase of IBMR values of polluted sites. For the latter, the Wilcoxon test was performed to assess the significance of the difference in quality between 2010 and 2013. This showed a statistically significant difference (p-value = 0.035). Our results showed similarities with previous data, as well as some differences. The differences observed might indicate a gradual change in the composition of the vegetation in the study area, which was caused by changes in environmental conditions. They could also reflect a lack of information about the ecology of certain groups of plants, mainly bryophytes and macroalgae that were not considered in previous studies. Despite the measures implemented under the EU's Water Framework Directive (WFD), the current vegetation of the Semois river differs little from that observed in 1996. The headwaters of a Semois river, described in previous studies as polytrophic and devoid of vegetation, show a slight improvement, with the appearance of macrophytic species. In some parts of the Chiers sub-basin, however, resistant species observed in 1999 persist. S.-A. Khadija et al.

Assessment of Macrophyte Biological Index for Rivers, and evaluation of physicochemical parameters in the Sakarya River Basin of Turkey

“…Industrial effluents, urbanization-related wastewater inputs, and excess fertilizer usage in agricultural activities are considered significant sources of increased eutrophication in freshwaters such as rivers, streams, and ponds (Chislock et al, 2013;Khatri and Tyagi, 2015). These factors modify the chemical and physical characteristics of freshwaters, thereby directly affecting the floral and faunal elements (Ceschin et al, 2010).…”

A new multi-criteria method for the ecological assessment of lakes: A case study from the Transboundary Biosphere Reserve ‘West Polesie’ (Poland)

“…Macrophytes are used successfully in good long time monitoring of ecologic variations, because they are characterized by low mobility (if compared with phytoplankton, fishes or invertebrates), and also in a relative short time monitoring because they are closely linked to biodiversity and the environmental conditions (Botineau and Ghestem, 1995;Van der Molen et al, 2004;Kolada, 2008;Cianfaglione, 2011;Khadija et al, 2015;Bolpagni et al, 2016aBolpagni et al, , 2016b. They are widely used for the aquatic ecosystems assessment, integrating the environmental changes in their frequency, communities structure, phenological rhythm, development (functional traits s.l.…”