Performance of macrophyte indicators to eutrophication pressure in ponds

Abstract

Aquatic macrophytes in ponds are considered as reliable indicators for detecting eutrophication pressure. In this study, the spatial distribution of total phosphorus (TP) and the ratio between transparency and water depth (ZSD/ZM) were characterized in Lake Baiyangdian, north China. Total P and ZSD/ZM were adopted to represent eutrophication pressure. The macrophyte indicators including richness of different species, diversity /evenness, biomass, and relative abundance for submerged/emergent (RAsub/eme) and sensitive/tolerant submerged species (RAsen/tol), were measured for each of the 38 ponds in the study area. Results showed that except richness of emergent and floating-leaved species, other macrophyte indicators were significantly correlated with TP and ZSD/ZM. Among them, evenness, biomass, RAsub/eme and RAsen/tol were selected to evaluate pond status because of their stronger response to TP.To evaluate the status for each pond, a scoring system was created by integrating TP and the four selected macrophyte indicators. We suggest that, control of external pollution sources and internal pollution sources, especially surface runoff from cropland reclamation and intensive use of fish feed from aquaculture, should be the focus of local managers. Inferred from the response of submerged species abundance to light availability, the value of ZSD/ZM should be no less than 0.52 to restore submerged species in eutrophic ponds.

Effects of substrate and water depth of a eutrophic pond on the physiological status of a submerged plant,Vallisneria natans

“…Light availability, which is regulated by water depth and transparency, has been identified as the main factor limiting the distribution of submerged plants including V. natans ( Voesenek et al, 2006 ; Bai et al, 2015 ; Dong et al, 2004 ; Han & Cui, 2016 ). The optimal water depth for the growth of V. natans has been reported as 100–160 cm in an oligotrophic lake ( Xiao, Yu & Wu, 2007 ), in which water transparency and light availability were high.…”

Peer Review #1 of "Effects of substrate and water depth of a eutrophic pond on the physiological status of a submerged plant, Vallisneria natans (v0.1)"

“…Light availability, which is regulated by water depth and transparency, has been identified as the main factor limiting the distribution of submerged plants including V. natans (Voesenek et al 2006, Bai et al 2015, Dong et al 2014, Han and Cui 2016. The optimal water depth for the growth of V. natans has been reported as 100-160 cm in an oligotrophic lake (Xiao et al 2017), in which water transparency and light availability were high.…”

“…However, a steep light attenuation with increasing depth in eutrophic lakes and ponds is likely to limit the distribution of V. natans to shallow areas. Han and Cui (2016) used the ratio of transparency to water depth as an indicator of eutrophication pressure on macrophyte communities. They suggested that the ratio should be no less than 0.52 to restore submerged species in eutrophic ponds.…”

Figure 2: Schematic view of the field experimental design (A) and arrangement of ramets in a cage (B).

“…Most area inside the study pond was near or greater than 2.0 m deep, at which the growth of V. natans is likely to be inhibited. Light availability, which is regulated by water depth and transparency, has been identified as the main factor limiting the distribution of submerged plants including V. natans (Voesenek et al, 2006;Bai et al, 2015;Dong et al, 2004;Han & Cui, 2016). The optimal water depth for the growth of V. natans has been reported as 100-160 cm in an oligotrophic lake (Xiao, Yu & Wu, 2007), in which water transparency and light availability were high.…”