Zoobenthos community structure and variation under different submerged macrophyte coverage in Shihoudian sub-lake in summer and autumn

Abstract:

To evaluate the community structure and changes of zoobenthos in summer and autumn under different submerged vegetation coverage, in July (summer) and October (autumn) of 2018, four coverage levels were selected in Shihoudian Lake, which were 25%, 50%, 75%, and 90% (C-25, C-50, C-75, C-90), and the control group is the area without submerged plants (C-0), and the respectively determined and analyzed the water physical and chemical parameters and zoobenthos community structure characteristics of each area. The results showed that:Submerged plants effectively reduced the concentration of total nitrogen (TN) and total phosphorus (TP). A total of 19 species were collected, belonging to 3 phyla, 4 classes, and 19 genera. Among them, the proportions of aquatic insects, gastropods, oligochaetes, and Lamellibranchia species were 68.42%, 15.79%, 10.52% and 5.26%, respectively; The number of benthic species in groups C-90, C-75, C-50, C-25 and C-0 was 10, 8, 11, 9 and 3, respectively. The Shannon-Weiner diversity index and Margalef richness index of zoobenthos increased first and then decreased with the increase of submerged vegetation coverage. Among them, the two diversity indexes of Zoobenthos in the C-50 group were significantly higher than those in other groups (P<0.05). Coverage, season, and the interaction effects of the two have significant effects on the density and biomass of zoobenthos (P<0.05), and the biomass of gastropods in the C-50 group in summer was significantly higher than that of other groups (P<0.05). Transparency, TDS and SPC are the main environmental factors affecting the distribution of Zoobenthos in summer and autumn. When the coverage is about 50%, the concentrations of TDS, SPC, TN and TP are the lowest, and the number of benthic species, Shannon-Weiner diversity index and Margalef richness index are the highest.