Optical proxy for phytoplankton biomass in the absence of photophysiology: Rethinking the absorption line height

Roesler, Collin S.; Barnard, Andrew H.

doi:10.1016/j.mio.2013.12.003

Cited by 115 publications

(124 citation statements)

References 46 publications

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“…is a proxy for Chl, but with physiological variability associated with solar quenching Roesler and Barnard, 2014) and nutrient stress (Cleveland and Perry, 1987). However, neither solar quenching nor Si limitation appears to be responsible for the difference in optical community index between Groups 1 and 2.…”

Section: Why Does the Chl F /B Bp Ratio Vary?mentioning

confidence: 98%

“…Phytoplankton biomass is assessed through several different optical proxies, including in situ chlorophyll a fluorescence (Chl F ; Lorenzen, 1966), the phytoplankton absorption coefficient (a phy (λ)) or particulate absorption coefficient in waters dominated by phytoplankton (Bricaud et al, 1995;Roesler and Barnard, 2014), and chlorophyll derived from in situ or remotely sensed ocean reflectance at visible wavelengths (O'Reilly et al, 1998). High-frequency optical measurements are ideal for detecting temporal change and spatial patchiness and for improving our understanding of the role of meso-and submesoscale physics in the distribution of phytoplankton in the ocean (Denman and Platt, 1976;Yoder et al,…”

Section: Introductionmentioning

confidence: 99%

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A simple optical index shows spatial and temporal heterogeneity in phytoplankton community composition during the 2008 North Atlantic Bloom Experiment

et al. 2015

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Abstract.The ratio of two in situ optical measurements -chlorophyll fluorescence (Chl F ) and optical particulate backscattering (b bp ) -varied with changes in phytoplankton community composition during the North Atlantic Bloom Experiment in the Iceland Basin in 2008. Using ship-based measurements of Chl F , b bp , chlorophyll a (Chl), highperformance liquid chromatography (HPLC) pigments, phytoplankton composition and carbon biomass, we found that oscillations in the ratio varied with changes in plankton community composition; hence we refer to Chl F /b bp as an "optical community index". The index varied by more than a factor of 2, with low values associated with pico-and nanophytoplankton and high values associated with diatomdominated phytoplankton communities. Observed changes in the optical index were driven by taxa-specific chlorophyllto-autotrophic carbon ratios and by physiological changes in Chl F associated with the silica limitation. A Lagrangian mixed-layer float and four Seagliders, operating continuously for 2 months, made similar measurements of the optical community index and followed the evolution and later demise of the diatom spring bloom. Temporal changes in optical community index and, by implication, the transition in community composition from diatom to post-diatom bloom communities were not simultaneous over the spatial domain surveyed by the ship, float and gliders. The ratio of simple optical properties measured from autonomous platforms, when carefully validated, provides a unique tool for studying phytoplankton patchiness on extended temporal scales and ecologically relevant spatial scales and should offer new insights into the processes regulating patchiness.

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Section: Why Does the Chl F /B Bp Ratio Vary?mentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

A simple optical index shows spatial and temporal heterogeneity in phytoplankton community composition during the 2008 North Atlantic Bloom Experiment

et al. 2015

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“…Cleveland and Perry, 1987;Roesler and Barnard, 2013;Sackmann et al, 2008). In this study, each profile of chlorophyll a fluorescence is converted into Chl following several considerations.…”

Section: Biogeochemical-argo Measurementsmentioning

confidence: 99%

Seasonal dynamics and disturbance of phytoplankton biomass in the wake of Tahiti as observed by Biogeochemical-Argo floats

Sauzède¹,

Martínez

Fommervault

et al. 2018

Preprint

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Abstract. The South Pacific Subtropical Gyre (SPSG) is a vast and remote area where large uncertainties on variability in phytoplankton biomass and production remain due to the lack of biogeochemical in situ observations. In such oligotrophic environments, ecosystems are predominantly controlled by nutrients depletion in surface waters. However, this oligotrophic 20 character can be disturbed in the vicinity of islands where enhancement of biological activity is known to occur (i.e. the island mass effect, IME). This study mainly focuses on in situ observations showing that an IME can be evidenced leeward of Tahiti the second one remained in the Tahitian wake (around 45 km from the island coasts). In the oligotrophic central SPSG, the wintertime increase in upper layer chlorophyll a concentration is likely due to photoacclimation process. Vertical observations show a light-driven deepening of the deep chlorophyll maximum (DCM) from winter to summer, consistently with previous descriptions. At the opposite, within the Tahitian wake, the DCM temporary widens during late spring in association with a biological enhancement in the upper layer. Combining in situ measurements with meteorological data along the Tahiti coasts, 30Hybrid Coordinate Ocean Model outputs and satellite-derived products (i.e., horizontal currents and associated fronts), the physical mechanisms involved in the disturbance of phytoplankton seasonal cycle in the Tahitian wake have been investigated. This disturbance results from the concomitant occurrence of strong precipitations and a zone of weak currents leeward Tahiti.We conjecture that the land drainage induces a significant supply of nitrate in the ocean upper layer (down to ~100 m) while a zone of weak currents in the southwestern zone behind Tahiti forms an accumulation zone, hence allowing phytoplankton 35 growth up to 20 km away from the coastlines. Moreover, bio-optical measurements suggest that the composition of

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“…Although observed patterns may indicate temporal and spatial variability of algal distribution in Milford Lake, differences also may be caused by variation in the relation between sensor-measured phycocyanin RFU, chlorophyll, and microcystin with depth. The phycocyanin sensor measures the fluorescence response of intracellular pigments, which may be affected by such factors as the thickness of algal cell walls, the physiological condition of the cells, and the heterogeneity of the algal communities being measured (Lawrenz and Richardson, 2011;Roesler and Barnard, 2013).…”

Section: Spatial Variability Of Harmful Algal Blooms In Milford Lakementioning

confidence: 99%

Spatial variability of harmful algal blooms in Milford Lake, Kansas, July and August 2015

Foster¹,

Graham²,

Stiles³

et al. 2017

Scientific Investigations Report

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Optical proxy for phytoplankton biomass in the absence of photophysiology: Rethinking the absorption line height

Cited by 115 publications

References 46 publications

A simple optical index shows spatial and temporal heterogeneity in phytoplankton community composition during the 2008 North Atlantic Bloom Experiment

A simple optical index shows spatial and temporal heterogeneity in phytoplankton community composition during the 2008 North Atlantic Bloom Experiment

Seasonal dynamics and disturbance of phytoplankton biomass in the wake of Tahiti as observed by Biogeochemical-Argo floats

Spatial variability of harmful algal blooms in Milford Lake, Kansas, July and August 2015

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