Year-end Sale % OFF 
Abstract
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·O2·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·O2·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.
Highlights
Tropical coral reefs and seagrass beds are shallow-water benthic communities of particular interest due to their high productivity and biodiversity, diverse environments, and high ecological and economic value [1,2,3]
Our results indicate that changes in light availability and quality by suspended or resuspended particles limit benthic productivity in the Florida Keys
At Sugarloaf Key in the Lower Florida Keys, tides and associated tidal currents, storms, and upwelling events led to short-term increases in turbidity and in spectral particulate absorption, attenuation and scattering in the patch reef and seagrass sites
Summary
Tropical coral reefs and seagrass beds are shallow-water benthic communities of particular interest due to their high productivity and biodiversity, diverse environments, and high ecological and economic value [1,2,3]. 2016, 8, 86 underwater light environment in these habitats is a complex function of variations in the percentage of sunlight reaching the ocean’s surface, light reflected and absorbed by water by diverse types of suspended living and detrital matter, dissolved substances, and by the benthos [5,6,7,8,9]. These changes in the underwater light field affect the productivity and ecological structure of these communities [10,11,12,13,14]. The nature of the sediments entering the coral ecosystem is important, as suspended terrigenous sediments such as silt and clay can reduce light penetration and coral photosynthesis more than reef-derived carbonate silt [16]
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
