Upstream nitrogen availability determines the Microcystis salt tolerance and influences microcystins release in brackish water

Copyright © 2024. Published by Elsevier Ltd..

The occurrence of large Microcystis biomass in brackish waters is primarily caused by its downward transportation from the upstream freshwater lakes and reservoirs through rivers rather than due to in situ bloom formation. Factors that determine the survival of freshwater cyanobacteria in brackish waters have not been well investigated. Here, we studied the spatiotemporal variability of inorganic nitrogen in an upstream lake and conducted laboratory and in-situ experiments to assess the role of nitrogen availability on the salt tolerance of Microcystis and the release of microcystins. A series of field experiments were carried out during bloom seasons to evaluate the salt tolerance of natural Microcystis colonies. The salt tolerance threshold varied from 7 to 17 and showed a positive relationship with intracellular carbohydrate content and a negative relationship with nitrogen availability in water. In August when upstream nitrogen availability was lower, the Microcystis colonies could maintain their biomass even after a sudden increase in salinity from 4 to 10. Laboratory-cultivated Microcystis that accumulated higher carbohydrate content at lower nitrogen availability showed better cell survival at higher salinity. The sharp release of microcystins into the surrounding water occurred when salinity exceeded the salt tolerance threshold of the Microcystis. Thus, Microcystis with higher salt tolerance can accumulate more toxins in cells. The obtained results suggest that the cell survival and toxin concentration in brackish waters depend on the physiological properties of Microcystis formed in the upstream waters. Thus, the life history of Microcystis in upstream waters could have a significant impact on its salt tolerance in downstream brackish waters, where the ecological risk of the salt-tolerant Microcystis requires special and careful management in summer at low nitrogen availability.

Medienart:

E-Artikel

Erscheinungsjahr:

2024

Erschienen:

2024

Enthalten in:

Zur Gesamtaufnahme - volume:252

Enthalten in:

Water research - 252(2024) vom: 15. Feb., Seite 121213

Sprache:

Englisch

Beteiligte Personen:

Li, Xinlu [VerfasserIn]
Li, Lei [VerfasserIn]
Huang, Yingying [VerfasserIn]
Wu, Haipeng [VerfasserIn]
Sheng, Shiwen [VerfasserIn]
Jiang, Xinran [VerfasserIn]
Chen, Xuechu [VerfasserIn]
Ostrovsky, Ilia [VerfasserIn]

Links:

Volltext

Themen:

059QF0KO0R
Brackish water
Carbohydrates
Journal Article
Microcystins
Microcystis blooms
N762921K75
Nitrogen
Nitrogen availability
Salt tolerance
Water

Anmerkungen:

Date Completed 29.02.2024

Date Revised 29.02.2024

published: Print-Electronic

Citation Status MEDLINE

doi:

10.1016/j.watres.2024.121213

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM367961318