Phytoplankton nutrient deficiencies vary with season in sub-tropical lakes of Nepal

Rowland, Freya E.; North, Rebecca L.; McEachern, Preston; Obrecht, Daniel V.; Gurung, Tek Bahadur; Jones, Susan B.; Jones, John R.

doi:10.1007/s10750-019-3897-8

Cited by 7 publications

(24 citation statements)

References 62 publications

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“…Thus, the variabilities of nutrients and algal growth in this monsoon region were more amplified than those in the areas of the non-monsoon region. A similar circumstance is found in other tropical and subtropical Asian reservoirs in China [12], Taiwan [13], Nepal [14], India [3], and Bangladesh [15]. This indicates that the summer monsoon may be a critical component, modifying the functional relationship among limnological variables.…”

Section: Introductionsupporting

confidence: 70%

“…Most of the freshwater reservoirs are P-limited throughout the world, which means that the algal growth is controlled by the concentration of phosphorus rather than nitrogen [3,19,20]. On the contrary, the N-limitation reservoir has been found in high altitude areas such as Colorado in the United States and Nepal [14,21]. Currently, the perception of N and P co-limitation has been extensively used and found in the United States, Northern Ireland, and Nepal [14,21,22].…”

Section: Introductionmentioning

confidence: 99%

“…On the contrary, the N-limitation reservoir has been found in high altitude areas such as Colorado in the United States and Nepal [14,21]. Currently, the perception of N and P co-limitation has been extensively used and found in the United States, Northern Ireland, and Nepal [14,21,22].…”

Section: Introductionmentioning

confidence: 99%

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Trophic Responses of the Asian Reservoir to Long-Term Seasonal and Interannual Dynamic Monsoon

Mamun

Kim

2020

Water

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The main objectives of the study were to determine the trophic response of the temperate reservoir to seasonal and interannual variabilities of monsoon inorganic solids and nutrients along the gradients of the morphologically complex Asian reservoir using long-term datasets between 2000–2018. Nutrient regime (total nitrogen—TN, total phosphorus—TP), total suspended solids (TSS), and chlorophyll-a (CHL-a) were primarily affected by an intensity of summer monsoon and the longitudinal structure of riverine (Rz), transitional (Tz), and lacustrine (Lz) zone. The reservoir is a nitrogen-rich system and the phosphorus content of the water was relatively low, and it had low mean N:P ratios (<40), implying a P-limiting system. The Lz was a highly P-limited zone in comparison to Rz and Tz zone during both drought (2015) and flood year (2011). The TP content was higher in the mainstem (S3) than the embankment (S4 and S6) of the reservoir due to the monsoon river inputs of the nutrients. Nonparametric Mann–Kendall tests indicated that TP decreased over the long-term years in the Rz, while it did not show any trend in Tz, Lz, IT1, and IT2. TN showed an increasing trend in Rz, Tz, Lz, and IT2 except for IT1. The empirical regression model for chlorophyll nutrients showed that CHL-a had a strong positive relationship with TP (R2 = 0.67, p < 0.01) than TN (R2 = 0.06, p < 0.01), supporting the view that algal growth in lentic systems responds to TP enrichment and TP may provide a reliable basis for predicting algal biomass. The seasonality of CHL-a and TP showed a monomodal pattern and indicates that summer TP influences summer algal growth in Tz, Lz, and IT2. The water clarity (SD) of the reservoir was significantly (p < 0.01) influenced by TP (R2 = 0.62), TSS (R2 = 0.67), and CHL-a (R2 = 0.68) rather than TN (R2 = 0.10). The non-algal light attenuation coefficient (Kna) was determined mainly by suspended solids and the monsoon hydrology. The trophic state was much higher when assessments were based on TSI (CHL-a) than on TSI (TP) and TSI (SD). TSI (CHL-a) indicated the eutrophic state of the reservoirs except for the zone of Lz during the premonsoon season. Analysis of trophic state index deviation (TSID) suggested that the blue-green algae dominated the algal community, and the effects of non-algal turbidity and zooplankton grazing were minor in the reservoir.

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Section: Introductionsupporting

confidence: 70%

Section: Introductionmentioning

confidence: 99%

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Trophic Responses of the Asian Reservoir to Long-Term Seasonal and Interannual Dynamic Monsoon

Mamun

Kim

2020

Water

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“…The traditional paradigm designates P as the single primary macronutrient controlling phytoplankton growth and productivity in temperate freshwater lakes (Schindler, 1974(Schindler, , 1977, but there is evidence that N, too, has a role to play (Morris and Lewis, 1988;Elser et al, 1990; Lewis and Wurtsbaugh, 2008;Abell et al, 2010). Numerous inland studies even offer evidence of simultaneous control by P and N (Elser et al, 2007;North et al, 2007;Sterner, 2008;Rowland et al, 2019) and/or light (Millard et al, 1996;Knowlton and Jones, 2000;Dubourg et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Filling in the Flyover Zone: High Phosphorus in Midwestern (USA) Reservoirs Results in High Phytoplankton Biomass but Not High Primary Productivity

Petty

Obrecht

North

2020

Front. Environ. Sci.

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In lakes and reservoirs, climate change increases surface water temperatures, promotes thermal stability, and decreases hypolimnetic oxygen. Increased anthropogenic land-use and precipitation enhance nutrient and sediment supply. Together, these effects alter the light and nutrient dynamics constraining phytoplankton biomass and productivity. Given that lake and reservoir processes differ, and that globally, reservoir numbers are increasing to meet water demands, reservoir-centric studies remain underrepresented. In the agricultural Midwest (United States), ubiquitous reservoirs experience eutrophy and hypolimnetic anoxia. Here, we explore influences of eutrophication and landuse on the proximate light and nutrient status of phytoplankton communities in 32 Missouri reservoirs. Light and nutrient status indicators include mixed layer irradiance, phosphorus (P) and nitrogen (N) stoichiometry/debts, photosynthetic efficiency, and photosynthetic-irradiance parameters. Contributing to the ongoing P vs. N and P management debate, we evaluate if phytoplankton biomass and productivity are constrained by light, P, N, or a combination thereof, across gradients of trophic status and land-use during two contrasting wet and dry summers. Despite agricultural prevalence, P-deficiency is more prominent than either Nor light-deficiency. In 2018, ∼46% of samples were P-deficient with ∼36% indicating neither light nor nutrient deficiency. Gross primary productivity per unit chlorophyll-a (GPP B) demonstrates negative relationships with nutrients, biomass, and turbidity, and positive relationships with light availability. GPP B is highest in oligotrophic reservoirs where light utilization efficiency is also highest. Overall, phytoplankton biomass and productivity appear constrained by P and light, respectively. If Midwestern reservoirs are precursors of future inland waters affected by climate change and eutrophication, our crystal ball indicates that both P and light will be important regulators of phytoplankton dynamics and subsequent water quality.

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“…The traditional paradigm designates P as the single primary macronutrient contributing to phytoplankton growth and productivity in temperate freshwater lakes (Schindler, 1974(Schindler, , 1977, but there is evidence that N, too, has a role to play (Morris and Lewis, 1988;Elser et al, 1990;Lewis and Wurtsbaugh, 2008;Abell et al, 2010). Numerous inland studies suggest simultaneous control between P and N (Elser et al, 2007;North et al, 2007;Sterner, 2008;Rowland et al, 2019) and/or light, which is another factor vital for phytoplankton growth and production in freshwaters (Millard et al, 1996;Knowlton and Jones, 2000;Dubourg et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

An assessment of the light and nutrient regimes constraining phytoplankton dynamics in Missouri reservoirs

Petty¹

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Worldwide, nutrient pollution, or eutrophication, is one of the most pervasive environmental issues threatening water quality. Anthropogenic influences, primarily urbanization and agriculture, have drastically increased inputs of bioavailable nutrients to surface water resources, such as lakes and reservoirs. Excessive phosphorus (P) and nitrogen (N) in these waters amplify the growth of suspended algae, or phytoplankton, resulting in unsightly, sometimes odorous, cyanobacterial harmful algal blooms (CyanoHABs) that further degrade water quality and potentially endanger human and animal health. As global climate change increases surface water temperatures, promotes water column stability, and drives down bottom-water oxygen concentrations, environmental conditions are also becoming more favorable for CyanoHABs. With eutrophication prevailing and CyanoHABs increasing in frequency, intensity, and distribution around the globe, I seek to further understand the role of light and nutrients as limiting agents for phytoplankton biomass and primary productivity across Midwestern reservoirs. I utilize numerous lines of evidence to create a robust assessment exploring the influences of climate, eutrophication, and land-use on the proximate light and nutrient status of phytoplankton in 32 Missouri reservoirs. Through observation and experimentation, deficiencies of light, P, and N are evaluated using general indicators of water quality and physiological stress, including mixed layer irradiance, nutrient stoichiometry/debts, photosynthetic efficiency, and the photosynthetic-irradiance (P-E) parameters. Ultimately, I determine if phytoplankton biomass and productivity are constrained by light, P, N, or a combination thereof, across gradients of trophic status and land-use within the context of two contrasting wet and dry summers. As expected, higher proportions of agricultural land-use correspond with higher total in-reservoir nutrient concentrations. Despite agricultural prevalence, however, bioavailable N concentrations in the mixed layer are, overall, relatively low. Yet, P-deficiency is more prominent than either N- or light-deficiency. For the 2018 season, I estimate nearly half of all samples to be P-deficient, with fewer than 20 percent suggesting alternative deficiency or co-deficiency combinations, and approximately one-third indicating sufficiency in both light and nutrients. Primary productivity demonstrates negative relationships with nutrients, biomass, and turbidity, and positive relationships with light. Thus, productivity is highest in clear, low-nutrient reservoirs where light utilization efficiency is also highest. Overall, in Missouri reservoirs, phytoplankton biomass and primary productivity are constrained by P and light, respectively. If current conditions in Missouri reservoirs are at all indicative of those to come as surface waters are further affected by climate change and eutrophication, both P and light will be important regulators of phytoplankton dynamics and subsequent water quality. Contributing to the ongoing P vs NP nutrient management debate, these results both support and challenge aspects of the traditional P-paradigm of limitation on phytoplankton dynamics. It underscores the importance of P control in reservoirs, while offering support for additional consideration of light and N. Having critical implications for watershed management throughout the region, these results are particularly useful within watersheds experiencing high agricultural nutrient loading. Results inform resource managers seeking to employ more effective strategies to control phytoplankton biomass, avoiding harmful regime shifts and CyanoHAB development. Additionally, results may inform lawmakers and regulators developing policies and standards to mitigate nutrient pollution and its effects on water quality at the local, regional, and, potentially, global scales.

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Phytoplankton nutrient deficiencies vary with season in sub-tropical lakes of Nepal

Cited by 7 publications

References 62 publications

Trophic Responses of the Asian Reservoir to Long-Term Seasonal and Interannual Dynamic Monsoon

Trophic Responses of the Asian Reservoir to Long-Term Seasonal and Interannual Dynamic Monsoon

Filling in the Flyover Zone: High Phosphorus in Midwestern (USA) Reservoirs Results in High Phytoplankton Biomass but Not High Primary Productivity

An assessment of the light and nutrient regimes constraining phytoplankton dynamics in Missouri reservoirs

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