Effects of Nitrogen and Phosphorus in Sediment on the Occurrence of Cladophora sp. (Cladophoraceae) in Aquaculture Ponds.

Zhang, Yuanyuan; Liu, Kaifang; Lv, Jun; Peng, Xinliang; Tang, Yongtao; Zhao, Liangjie; Cheng, Yongxu; Liu, Qigen

Simple Summary: The overgrowth of Cladophora poses a threat to aquatic environments and cultured animals. This study investigated the effects of nitrogen and phosphorus levels in sediment on the growth of Cladophora in aquaculture ponds, which is a significant issue affecting water quality and aquatic life. We conducted microecosystem experiments to simulate varying nutrient conditions, discovering that a nitrogen-to-phosphorus ratio of 40:1 negatively impacts Cladophora growth. Our findings also indicated that benthic cyanobacteria, which formed dense mats on the sediment surface, can inhibit the growth of Cladophora, showing a strong negative correlation between their coverage and the wet weight of Cladophora. Furthermore, we found that total nitrogen levels in the water have a positive relationship with phytoplankton biomass, while benthic cyanobacteria coverage is linked to phytoplankton biomass through its role in phosphorus absorption and nitrogen release. Metabolite analysis identified several key compounds in benthic cyanobacteria, although none were recognized as allelochemicals or toxins. This research offers new insights into managing Cladophora by considering sediment nutrients and their interactions with benthic cyanobacteria, which could be valuable for improving aquaculture practices and preserving aquatic ecosystems. To explore the impact of sedimentary nitrogen and phosphorus on Cladophora occurrence, we conducted a microecosystem experiment simulating different nitrogen and phosphorus content as well as nitrogen-to-phosphorus ratios in the sediment. Subsequently, to further explore the specific mechanism of influence that epiphytic algae have on Cladophora, we designed various microsystem culture experiments. These results revealed that an N/P ratio of 40:1 was relatively unfavorable for Cladophora growth. Additionally, there was an extremely significant negative correlation between the benthic cyanobacteria coverage on the sediment surface and the wet weight of Cladophora (p < 0.01), indicating that benthic cyanobacteria could inhibit the growth of Cladophora. Total nitrogen levels in the water column showed a significant positive correlation with phytoplankton biomass (p < 0.05), while benthic cyanobacteria coverage exhibited an extremely significant positive correlation with phytoplankton biomass through phosphorus absorption and nitrogen release (p < 0.01). Metabolite analysis of benthic cyanobacteria identified annotations for 313 metabolites; among them cis,cis-muconic acid (32.48‰), erucamide (9.52‰), phosphoric acid (6.97‰), fenpropidin (6.53‰), and propionic acid (5.16‰) accounted for proportions exceeding 5‰. However, none of these metabolites have been recognized as allelochemicals or toxins at present. This study provides novel insights into controlling Cladophora occurrence by considering sediment nutrients, including nitrogen and phosphorus, along with allelochemicals.

CLADOPHORA; NITROGEN in water; PROPIONIC acid; WATER levels; WATER quality; CYANOBACTERIAL toxins

Biology (2079-7737), 2024, Vol 13, Issue 9, p739

2079-7737

Academic Journal

10.3390/biology13090739