Quantitative and qualitative variability of epiphytic algae on one Apiaceae (Apium nodiflorum L.) in a karstic river (Southeast of France)

Abstract

Spatial distribution of the firmly attached epiphytic algae was investigated directly on the leaves of one Apiaceae (Apium nodiflorum L.) commonly found in chalky Mediterranean rivers, at two sampling dates (summer and autumn). The composition and structure of the epiphytic communities of the samples were determined at different levels: along the leaves, on both their sides and within each leaflet (n ¼ 13). Forty-eight leaflets from four randomly selected plants were cut along the longitudinal and vertical axes so as to define 16 microhabitats located on the edge, the centre and the vein. Only a few species of algae were found to be constantly present whatever the sampling date, and dominated all microzones (n ¼ 768). Their presence seemed to depend, rather, on the architectural structure of the plant. The other algae represented the major part of the epiphytic community and were only occasionally present. Those were more subject to temporal and environmental variations and less specific of the substrate. The epiphytes showed considerable spatial heterogeneity within their microhabitats, with an evident preference for the centre and the edge of the leaves, whereas two inhospitable spaces were the vein and apex. On the other hand, when the study was performed at a larger scale (along the leaf), the epiphytic populations of the youngest leaves (near the surface) and the eldest ones (close to the sediments) were homogenous, hence suggesting that other factors, independent from the physiology of the plant, may have an impact on epiphytic distribution.

LINKING BENTHIC ALGAL BIOMASS TO STREAM SUBSTRATUM TOPOGRAPHY1

“…Thus, similar mechanisms may be regulating algal growth at both macro-and microscales. For example, edges of substrata tend to accumulate more algae than the interior surface (Comte et al 2005), and rougher textured substrata (i.e., those with more microscale edges) tend to collect more algae (Clifford et al 1992, Sanson et al 1995. Additionally, algal cell attachment efficiency has been observed to increase with roughness at scales ranging from 1 to 14 lm (Scardino et al 2006), from 0.1 to 1.2 mm (Johnson 1994), and from 2.0 to 4.0 mm (Sanson et al 1995).…”

“…Thus, similar mechanisms may be regulating algal growth at both macro‐ and microscales. For example, edges of substrata tend to accumulate more algae than the interior surface (Comte et al. 2005), and rougher textured substrata (i.e., those with more microscale edges) tend to collect more algae (Clifford et al.…”

Epiphytic, littoral diatoms as bioindicators of shallow lake trophic status: Trophic Diatom Index for Lakes (TDIL) developed in Hungary

“…The EC Water Framework Directive (WFD; EC Parliament and Council, 2000) initiated a number of research focusing on basic concepts (Furse et al, 2006), typology of surface waters (Sandin & Verdonschot, 2006) and various kinds of methodical approaches (Comte et al, 2005;Besse-Lototskaya et al, 2006;Persson et at., 2006;Springe et al, 2006).…”

Serial Use of Helosciadum nodiflorum and Typha latifolia in Mediterranean Constructed Wetlands to Naturalize Effluents of Wastewater Treatment Plants

“…Apart from nicely illustrating the naturalization process of the already treated wastewater, the main novelty of our study was the use of H. nodiflorum, a native macrophyte that regularly appears in the streams of Europe. This plant shows a large standing biomass in rivers, even when temperatures and nutrients content are low [24], which makes it suitable for the water naturalization processes, even during the colder months under a Mediterranean climate. This naturalization consisted mainly in both the removal and the transformation of the remaining pollutants.…”