Effect of Aquatic Vegetation Restoration after Removal of Culture Purse Seine on Phytoplankton Community Structure in Caizi Lakes

Abstract

Many reports have demonstrated that the removal of aquaculture purse seine is conducive to the restoration of aquatic vegetation and the improvement in water quality, but less attention has been paid to the effects on phytoplankton. This paper addressed the response of phytoplankton community structure to aquatic vegetation restoration after purse seine removal in Caizi Lakes. The results showed that the average dissolved oxygen (from 7.43 ± 0.25 mg/L to 9.12 ± 0.49 mg/L) and Secchi depth (from 28.40 ± 6.20 cm to 47.61 ± 14.62 cm) in the water column of the Caizi Lakes increased after the restoration of aquatic vegetation, while the average concentrations of total nitrogen (from 2.00 ± 0.16 mg/L to 1.34 ± 0.18 mg/L) and total phosphorus (from 0.15 ± 0.02 mg/L to 0.06 ± 0.01 mg/L) decreased. After the restoration of the aquatic vegetation, the cell density of phytoplankton declined from 21.04 ± 4.57 × 106 cells/L to 12.74 ± 3.63 × 106 cells/L, and the biomass fell from 18.13 ± 3.57 mg/L to 9.72 ± 2.55 mg/L. We also observed that Shannon–Wiener diversity, Margalef and Pielou indices of phytoplankton surged by 66.50%, 46.20% and 84.68%, respectively. Because this study demonstrated that aquatic vegetation could alleviate the eutrophication, it can provide guidance for the restoration and protection of the aquatic ecosystem.

Metagenomic analysis of gut microbiota and antibiotic-resistant genes in Anser erythropus wintering at Shengjin and Caizi Lakes in China

“…The gut microbiota and ARGs in A. erythropus wintering at the two lakes were correlated with the physicochemical properties of the two lakes. It was previously reported that the concentrations of chemical ions in the surface and groundwater of the study area were higher than those of atmospheric precipitation, while total phosphorus, total nitrogen, chlorophyll-a, and transparency values of the surface water pointed to eutrophication (Cui et al, 2021 ; Gao et al, 2022 ; Zhao et al, 2022 ). The trophic state index and bacterial eutrophic index values showed that the two lakes were slightly eutrophic (Gao et al, 2022 ; Zhao et al, 2022 ).…”

“…It was previously reported that the concentrations of chemical ions in the surface and groundwater of the study area were higher than those of atmospheric precipitation, while total phosphorus, total nitrogen, chlorophyll-a, and transparency values of the surface water pointed to eutrophication (Cui et al, 2021;Gao et al, 2022; Zhao et al, 2022). The trophic state index and bacterial eutrophic index values showed that the two lakes were slightly eutrophic (Gao et al, 2022;Zhao et al, 2022). These previously reported results indicate that the physicochemical properties of these two lakes affect the structure and function of the gut microbiota and ARGs in A. erythropus.…”

Differences in Waterbird Communities between Years Indicate the Positive Effects of Pen Culture Removal in Caizi Lake, a Typical Yangtze-Connected Lake

“…Fox et al [26] reported that an increase in aquatic vegetation attracts a large number of waterbirds. Therefore, the increase in the waterbird abundance after purse seine removal in Caizi Lake may be attributed to the substantial recovery of aquatic vegetation [46]. The artificial acceleration of the restoration of aquatic vegetation in Caizi Lake is conducive to the increase in the waterbird abundance.…”

“…Caizi Lake has a long history of aquaculture. Net pens were constructed in the lake in the 1990s, covering more than 90% of its area [46]. Intensive aquaculture has destroyed aquatic vegetation, particularly submerged vegetation, throughout the lake.…”

“…In response to nationwide environmental inspections and the Yangtze River Grand Protection Policy, net pens in Caizi Lake were completely removed in March 2018 to restore the wetland ecosystem [40]. A total area of about 58 km 2 and a length of about 170 km of nets were removed from Caizi Lake [46].…”