期刊
MICROORGANISMS
卷 9, 期 10, 页码 -出版社
MDPI
DOI: 10.3390/microorganisms9102097
关键词
bioavailable nutrients; nitrogen; phosphorus; precipitation; cyanobacterial blooms; Dolichospermum; Microcystis
类别
资金
- Government of Canada
- interdepartmental Genomics Research and Development Initiative
- Metagenomics Based Ecosystem Biomonitoring (EcoBiomics) project
- Genome Canada/Genome Quebec grant for the Algal Blooms, Treatment, Risk Assessment, Prediction and Prevention through Genomics (ATRAPP) project
This study investigated the sources of nitrogen and phosphorus nutrients, as well as the impact of runoff on cyanobacterial blooms. The results showed that peaks in nitrogen and phosphorus concentrations were associated with intense cumulative precipitation events, and that nitrogen and phosphorus had a significant influence on cyanobacterial population dynamics.
Anthropogenic activities release large amounts of nitrogen (N) and phosphorus (P) nutrients into the environment. Sources of nutrients include surface and sub-surface runoffs from agricultural practices with the application of chemical fertilizers and manure as well as combined sewer overflows (CSOs). Nutrient runoffs contribute to the eutrophication of aquatic ecosystems and enhance the growth of cyanobacteria. Precipitation is an important driving force behind the runoff of nutrients from agricultural fields into surrounding water bodies. To understand the dynamics between nutrient input, precipitation and cyanobacterial growth in Missisquoi Bay, Lake Champlain (Quebec), one location in Pike River (a major tributary into the bay) and four locations in Missisquoi Bay were monitored from April to November in 2017 and 2018. Biweekly water samples were analyzed using chemical methods and high-throughput sequencing of 16S rRNA gene amplicons. High concentrations of N and P were typically measured in April and May. Three major spikes in nutrient concentrations were observed in early and mid-summer as well as early fall, all of which were associated with intense cumulative precipitation events of 40 to 100 mm within 7 days prior to sampling. Despite the high concentrations of nutrients in the spring and early summer, the cyanobacterial blooms appeared in mid to late summer as the water temperature increased. Dolichospermum sp. was the major bloom-forming cyanobacterium during both summers. A second intense bloom event of Microcystis was also observed in the fall (October and November) for both years. Variation in the cyanobacteria population was strongly associated with inorganic and readily available fractions of N and P such as nitrites and nitrates (NOx), ammonia (NH3) and dissolved organic phosphorus (DOP). During blooms, total Kjeldahl nitrogen (TKN) and total particulate phosphorus (TPP) fractions had a substantial influence on total nitrogen (TN) and total phosphorus (TP) concentrations, respectively. The abundance of bacteria involved in the metabolism of nitrogen compared to that of phosphorus revealed the importance of nitrogen on overall microbial dynamics as well as CB formation in the bay. Our findings emphasize the combined influence of precipitation events, temperature and several bioavailable fractions of nitrogen and phosphorus on cyanobacterial bloom episodes.
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