Moore, Tim: Florida Atlantic University (Project Lead)
Project Funding:
2016 - 2020
NRA: 2015 NASA: Ocean Biology and Biogeochemistry
Funded by NASA
Abstract:
We are proposing to study the biogeochemical interactions between sediment resuspension and algal growth in western Lake Erie using a combination of in situ observations, laboratory experiments, model development and ocean color remote sensing data. Our main hypothesis is that wind-induced sediment resuspension events release bioavailable nutrients into the water column, and stimulate algal blooms including harmful cyanobacteria in western Lake Erie. Our proposal is directed towards NASA’s Ocean Biology and Biogeochemistry program section 2.1, and is well suited to fit within this program.
The current paradigm is that spring runoff and associated nutrient loading of western Lake Erie primarily through the Maumee River dictates the intensity of summer cyanobacteria blooms, which contain toxic species. Despite substantial research efforts, the mechanisms and drivers of these blooms are still poorly understood, as there is a time lag of months between the spring loading and the summer bloom peak.
A knowledge gap exists in how these events are connected, although there are theories. Our proposal will specifically address one of the possible mechanisms for nutrient delivery to the water column spurring algal growth in the summer sediment resupension from wind events and coupled with biogeochemical release of nutrients into the water column. Our previous work in western Lake Erie provides some evidence that initiation of algal blooms in the summertime are linked to sediment resuspension events, but the degree to which resuspended sediments contribute to fueling the massive cyanobacteria blooms is unknown. We propose to quantify this mechanism on short time scales with in situ instruments deployed on two buoys to continuously measure in-water properties, and with laboratory experiments on resuspension of sediment cores
collected in the western basin, nutrient fluxes and growth of cyanobacteria.
We will use optical properties as proxies to relate sediments with nutrients, and use remote sensing data to estimate nutrient availability across the western basin. We will use the remote sensing data to derive a seasonal estimate of the nutrient loading from sediment resuspension that can be directly compared to river nutrient loading during the spring and summer.
The major outcomes of the study will be:
o Quantification of nutrient release through resuspension as a function of total suspended solids (TSS) derived from erosion chamber experiments and linked to cyanobacteria growth experiments.
o Quantification of TSS through optical models and associated nutrient release from in situ sensors at high temporal resolution at the two buoy sites.
o Quantification of basin-wide phytoplankton response through satellite ocean color
observations that will lead to seasonal estimates for basin-wide internal loading.
o Evaluation of the loading estimates from the combined field work, lab experiments and
satellite data that will be directly compared to spring and summer loading through river
runoff, providing a measure of relevance for the role of resuspension in fueling algal
blooms in western Lake Erie.
As we will be measuring continuous in-water optical properties, our data will be available and valuable to the PACE bio-optical and atmospheric correction modeling community which is currently defining the science requirements for the NASA PACE satellite. In addition, the same data sets will be available and valuable to ESA with the recent launch of the Sentinel-3 satellite for the same reasons. More broadly, there will be benefits to agencies and scientists involved with ocean color satellite missions, specifically those which are seeking to improve their product
quality in coastal and lake applications.
More details may be found in the following project profile(s):
