Optics and remote sensing of Bahamian carbonate sediment whitings and potential relationship to wind-driven Langmuir circulation

Dierssen, Heidi M.; Zimmerman, Richard C.; Burdige, David J.

doi:10.5194/bg-6-487-2009

Cited by 52 publications

(56 citation statements)

References 55 publications

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“…Particulate attenuation coefficients were higher at the patch reef after the storm of 17 October, when winds >10 m¨s´1 occurred. Dierssen et al [31] concluded that winds >7.35 m¨s´1 can trigger resuspension of sediments over the Bahamas Banks at depths of about 5 m. Lapointe et al [71] also proposed that winds play an important role in the dynamics of nutrients and chlorophyll concentrations by changing advection patterns in the Lower Florida Keys. Our results show high turbidity and c p conditions due to suspended sediments under these short high wind events, which are quite common in Florida during summer.…”

Section: Discussionmentioning

confidence: 99%

Characterization of Available Light for Seagrass and Patch Reef Productivity in Sugarloaf Key, Lower Florida Keys

et al. 2016

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Light availability is an important factor driving primary productivity in benthic ecosystems, but in situ and remote sensing measurements of light quality are limited for coral reefs and seagrass beds. We evaluated the productivity responses of a patch reef and a seagrass site in the Lower Florida Keys to ambient light availability and spectral quality. In situ optical properties were characterized utilizing moored and water column bio-optical and hydrographic measurements. Net ecosystem productivity (NEP) was also estimated for these study sites using benthic productivity chambers. Our results show higher spectral light attenuation and absorption, and lower irradiance during low tide in the patch reef, tracking the influx of materials from shallower coastal areas. In contrast, the intrusion of clearer surface Atlantic Ocean water caused lower values of spectral attenuation and absorption, and higher irradiance in the patch reef during high tide. Storms during the studied period, with winds >10 m¨s´1, caused higher spectral attenuation values. A spatial gradient of NEP was observed, from high productivity in the shallow seagrass area, to lower productivity in deeper patch reefs. The highest daytime NEP was observed in the seagrass, with values of almost 0.4 g¨O 2¨m´2¨h´1 . Productivity at the patch reef area was lower in May than during October 2012 (mean = 0.137 and 0.177 g¨O 2¨m´2¨h´1 , respectively). Higher photosynthetic active radiation (PAR) levels measured above water and lower light attenuation in the red region of the visible spectrum (~666 to~699 nm) had a positive correlation with NEP. Our results indicate that changes in light availability and quality by suspended or resuspended particles limit benthic productivity in the Florida Keys.

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Section: Discussionmentioning

confidence: 99%

Characterization of Available Light for Seagrass and Patch Reef Productivity in Sugarloaf Key, Lower Florida Keys

et al. 2016

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“…Hurricanes Edouard and Hortense introduced enough energy into a 70 m deep water column to resuspend bottom sediments over 30 m above the bottom [Chang et al, 2001]. Even lower but persistent winds can cause shallow water Langmuir "Supercells" that can serve to redistribute benthic algae and resuspend sediments off the seafloor [Gargett et al, 2004;Dierssen et al, 2009aDierssen et al, , 2009b. Once suspended, sediments can persist in the water column for several days.…”

Section: Temporal Variability In Particle Size Distributionsmentioning

confidence: 99%

A regional comparison of particle size distributions and the power law approximation in oceanic and estuarine surface waters

2010

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[1] The particle size distribution (PSD) is commonly used in studies of sediment fluxes, phytoplankton dynamics, and optical scattering from particulates, but little is known about the spatial and temporal variability of this parameter. Here, we analyze in situ laser diffraction measurements of the PSD from a variety of estuarine and open ocean systems. The power law or "Junge-type" distribution provided a good fit to surface ocean particle size distributions measured from 6 to 250 mm. PSD slopes ranged from 2.7 to 4.7 with a mean of 3.63. Consistent with theory, high particle slopes (3.78) and low particle concentrations characterized the open ocean waters of the Atlantic and the Southern Ocean. Lower PSD slopes (3.63) and high concentrations were characteristic of estuarine waters. River plumes consistently showed the lowest PSD slopes (3.30) and highest particle concentrations characteristic of larger bloom-forming phytoplankton and production of particle aggregates. In the North Atlantic, an inverse relationship was found between PSD slope and chlorophyll concentration. Such results follow the biological paradigm that larger phytoplankton are prevalent in bloom conditions and smaller phytoplankton dominate in oligotrophic water. Large temporal variability in PSD was observed in near coastal regions prone to sediment resuspension from storms and tidal flow. Dense sea grass beds consistently had lower particle concentrations compared to surrounding waters due to reductions in current flow and sediment resuspension. Simple power law approximations of particle size distributions can be successfully used to describe and assess particle distributions in a wide array of oceanic and estuarine water types.Citation: Buonassissi, C. J., and H. M. Dierssen (2010), A regional comparison of particle size distributions and the power law approximation in oceanic and estuarine surface waters,

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“…Suspended sediments, like the aragonite mud on the Great Bahama Bank, highly backscatter light out of the water (35). The size, outer coating, and 3D structure all influence the specific backscattering properties of phytoplankton (36).…”

Section: Backscattering Propertiesmentioning

confidence: 99%

Perspectives on empirical approaches for ocean color remote sensing of chlorophyll in a changing climate

Dierssen

2010

Proc. Natl. Acad. Sci. U.S.A.

164

107

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Phytoplankton biomass and productivity have been continuously monitored from ocean color satellites for over a decade. Yet, the most widely used empirical approach for estimating chlorophyll a (Chl) from satellites can be in error by a factor of 5 or more. Such variability is due to differences in absorption and backscattering properties of phytoplankton and related concentrations of colored-dissolved organic matter (CDOM) and minerals. The empirical algorithms have built-in assumptions that follow the basic precept of biological oceanography -namely, oligotrophic regions with low phytoplankton biomass are populated with small phytoplankton, whereas more productive regions contain larger bloom-forming phytoplankton. With a changing world ocean, phytoplankton composition may shift in response to altered environmental forcing, and CDOM and mineral concentrations may become uncoupled from phytoplankton stocks, creating further uncertainty and error in the empirical approaches. Hence, caution is warranted when using empirically derived Chl to infer climaterelated changes in ocean biology. The Southern Ocean is already experiencing climatic shifts and shows substantial errors in satellitederived Chl for different phytoplankton assemblages. Accurate global assessments of phytoplankton will require improved technology and modeling, enhanced field observations, and ongoing validation of our "eyes in space." biological oceanography | phytoplankton | primary productivity | satellite oceanography | ocean optics

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Optics and remote sensing of Bahamian carbonate sediment whitings and potential relationship to wind-driven Langmuir circulation

Cited by 52 publications

References 55 publications

Characterization of Available Light for Seagrass and Patch Reef Productivity in Sugarloaf Key, Lower Florida Keys

Characterization of Available Light for Seagrass and Patch Reef Productivity in Sugarloaf Key, Lower Florida Keys

A regional comparison of particle size distributions and the power law approximation in oceanic and estuarine surface waters

Perspectives on empirical approaches for ocean color remote sensing of chlorophyll in a changing climate

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