Improved estimation of carbon fixation rates from active flourometry using spectral fluorescence in light‐limited environments

Silsbe, Greg M.; Hecky, Robert E.; Smith, Ralph E. H.

doi:10.4319/lom.2012.10.736

Cited by 10 publications

(5 citation statements)

References 51 publications

(79 reference statements)

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“…Therefore, this study critically evaluates bio‐optical models that parameterize

P_{e}

, with a key emphasis on

a_{PSII} (λ)

methodology. As estimates of

a_{PSII} (λ)

likely cause the largest uncertainty in

P_{e}

measurements (Silsbe et al ), it is not clear if and how the growing number of

P_{e}

datasets, and by extension

Φ_{e, C}

datasets, can be reconciled. This study builds on a previous methods evaluation (Suggett et al ) by incorporating recent advances in bio‐optical instrumentation and algorithms (Röttgers and Doerffer ; Oxborough et al ).…”

Section: Overview Of Four Bio‐optical Methods That Quantify Apsii(λ)mentioning

confidence: 99%

Toward autonomous measurements of photosynthetic electron transport rates: An evaluation of active fluorescence‐based measurements of photochemistry

Silsbe

Oxborough

Suggett

et al. 2015

Limnology & Ocean Methods

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This study presents a methods evaluation and intercalibration of active fluorescence-based measurements of the quantum yield (/ 0 PSII ) and absorption coefficient (a PSII ) of photosystem II (PSII) photochemistry. Measurements of / 0 PSII , a PSII , and irradiance (E) can be scaled to derive photosynthetic electron transport rates (P e ), the process that fuels phytoplankton carbon fixation and growth. Bio-optical estimates of / 0 PSII and a PSII were evaluated using 10 phytoplankton cultures across different pigment groups with varying bio-optical absorption characteristics on six different fast-repetition rate fluorometers that span two different manufacturers and four different models. Culture measurements of / 0 PSII and the effective absorption cross section of PSII photochemistry (r PSII , a constituent of a PSII ) showed a high degree of correspondence across instruments, although some instrument-specific biases are identified. A range of approaches have been used in the literature to estimate a PSII ðkÞ and are evaluated here. With the exception of ex situ a PSII ðkÞ estimates from paired r PSII and PSII reaction center concentration (½RCII) measurements, the accuracy and precision of in situ a PSII ðkÞ methodologies are largely determined by the variance of method-specific coefficients. The accuracy and precision of these coefficients are evaluated, compared to literature data, and discussed within a framework of autonomous P e measurements. This study supports the application of an instrument-specific calibration coefficient (K R ) that scales minimum fluorescence in the dark (F 0 ) to a PSII as both the most accurate in situ measurement of a PSII , and the methodology best suited for highly resolved autonomous P e measurements.V C 2014 Association for the Sciences of Limnology and Oceanography Improved monitoring of phytoplankton productivity (PP) is a core goal across the aquatic sciences and underpins long term management plans for coastal seas and the global ocean (European Marine Board 2013). Following the success of global ocean observatory systems such as the free-drifting Argo profilers (http://www.argo.ucsd.edu/), scientists are now looking to integrate instruments that are capable of autonomous biological rate and flux measurements into environmental sensor networks (Claustre et al. 2010). Unlike traditional in vitro photosynthetic assays, active fluorescence-based photosynthetic measurements are well suited for environmental sensor networks as many of these optical instruments can operate autonomously providing high resolution in situ photosynthesis measurements. Bio-optical models scale active fluorescence measurements to generate estimates of electron transport rates by photosystem II (P e ), whose reductant yield fuels carbon fixation and growth. The derivation of P e is shown in Eq. 1 as the product of photon irradiance (EðkÞ), the absorption coefficient of photosystem II (PSII) light-harvesting pigments (a LHII ðkÞ), and E-dependent measurements of the quantum yield of PSII pho...

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“…Therefore, this study critically evaluates bio‐optical models that parameterize

P_{e}

, with a key emphasis on

a_{PSII} (λ)

methodology. As estimates of

a_{PSII} (λ)

likely cause the largest uncertainty in

P_{e}

measurements (Silsbe et al ), it is not clear if and how the growing number of

P_{e}

datasets, and by extension

Φ_{e, C}

Section: Overview Of Four Bio‐optical Methods That Quantify Apsii(λ)mentioning

confidence: 99%

Toward autonomous measurements of photosynthetic electron transport rates: An evaluation of active fluorescence‐based measurements of photochemistry

Silsbe

Oxborough

Suggett

et al. 2015

Limnology & Ocean Methods

View full text Add to dashboard Cite

show abstract

“…where A P is absorption before and A NAP is absorption after depigmentation, β is the path-length amplification factor to adjust for differences in absorption between water and filter, and V f /A f is the ratio of volume of water filtered to the filter area (Silsbe et al, 2012). We determined GPP using the R package phytotools (Silsbe and Malkin, 2015).…”

Section: Laboratory Analysesmentioning

confidence: 99%

Phytoplankton Community Response to Changes in Light: Can Glacial Rock Flour Be Used to Control Cyanobacterial Blooms?

Gaskill

Harris

North

2020

Front. Environ. Sci.

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Cyanobacterial harmful algal blooms are one of the most prominent threats to water quality in freshwater ecosystems and are expected to become more common as the climate continues to change. While traditional strategies to manage algal blooms have focused on controlling nutrients, manipulating light as a way to reduce cyanobacteria is less frequently explored. Here, we propose the addition of glacial rock flour (GRF), a fine particulate that floats on the water's surface and remains suspended in the water column, to reduce light availability and in turn, phytoplankton biomass dominated by cyanobacteria. To determine if a sustained reduction in light could lower cyanobacteria biomass and microcystin concentrations, we applied GRF to large-scale (11 kL) mesocosm tanks for 9 consecutive days. Mesocosm tanks were amended by adding nitrogen and phosphorus to generate chlorophyte-and cyanophyte-dominated experimental tanks. To assess how the phytoplankton community was impacted in each tank, we measured photosynthetic irradiance parameters, the maximum quantum yield of photosystem II, gross primary productivity (GPP), phytoplankton biovolume, and phytoplankton community composition before and after the addition of GRF. GRF effectively reduced cyanophyte biovolume by 78% in the cyanophytedominated tanks, despite no significant change in total phytoplankton community biovolume. Cyanophytes were replaced by cryptophytes, which increased by 106% in the chlorophyte-dominated tanks and by 240% in the cyanophyte-dominated tanks. The change in photosynthetic irradiance parameters and GPP after the addition of GRF was not significantly different between any of the treatment or control groups, suggesting that either the cyanophytes will likely recover if light availability increases, or that the new cryptophyte-dominated community was well suited to a reduced light environment. Cyanobacterial blooms are expected to increase in frequency and magnitude as climate change progresses, but our study suggests that light manipulation may be a useful in-lake management strategy for controlling these blooms and warrants further investigation.

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“…UV/VIS, Santa Clara, California, US) in 1 nm increments from wavelengths 350 to 750 nm. I calculated aφ based on Silsbe et al (2012):…”

Section: Biological Parametersmentioning

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.

show abstract

Improved estimation of carbon fixation rates from active flourometry using spectral fluorescence in light‐limited environments

Cited by 10 publications

References 51 publications

Toward autonomous measurements of photosynthetic electron transport rates: An evaluation of active fluorescence‐based measurements of photochemistry

Toward autonomous measurements of photosynthetic electron transport rates: An evaluation of active fluorescence‐based measurements of photochemistry

Phytoplankton Community Response to Changes in Light: Can Glacial Rock Flour Be Used to Control Cyanobacterial Blooms?

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

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