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New Study Highlights Need for Integrated Nutrient Monitoring

June 12, 2024
Shell Point 1600

A sensor on SCCF’s River, Estuary, and Coastal Observing Network (RECON) Shell Point monitoring platform played a key role in a pilot study for the development of a nutrient monitoring program across Gulf of Mexico estuaries. 

The results of the study are featured in the August 2024 issue of Environmental Technology & Innovation.

“The study demonstrated that collecting nutrient data more frequently can provide necessary data on nutrient sources and potential triggers for algal blooms,” said SCCF Marine Lab Director Eric Milbrandt, Ph.D., lead author of the study. “More frequent nutrient data can also be useful for outreach about sources of nitrogen pollution in our estuaries, including fertilizers and stormwater runoff.” 

Problem with Nutrient Pollution

 With nutrient pollution as an ongoing challenge for water quality worldwide, the study recognized that much of the problem originates in inland watersheds, with many of the effects seen in coastal and estuarine waters that experience eutrophication, harmful algal blooms (HABs), and hypoxia.

Eutrophication is the gradual increase in the concentration of phosphorus, nitrogen, and other nutrients. Hypoxia refers to low or depleted oxygen in a water body that can lead to ‘dead zones ‘ or areas where life cannot be sustained.

High-nutrient runoff from agricultural lands and urban areas have been found to be the main causes of coastal eutrophication which can stimulate HABs that cause millions of dollars in damages annually.

To support research and management to assess the effectiveness of upstream nutrient reduction efforts on coastal water quality, the study looked at the role of enhanced nutrient monitoring.

Testing at RECON & LUMCON

It tested the operational status and integration of a commercial, in situ chemical analyzer for nitrate in two existing monitoring programs — SCCF’s RECON and one at the Louisiana Universities Marine Consortium (LUMCON) DeFelice Marine Center. 

Wet chemical nitrate sensors or WIZ (Water In Situ AnalyZer) probes were deployed at the mouth of the Caloosahatchee River and at the northern boundary of Terrebonne Bay in a saltwater marsh ecosystem that receives freshwater from the Mississippi and Atchafalaya Rivers, which increases nutrient inputs to these ecosystems, mainly from upstream fertilizer use.

The RECON WIZ was operational for approximately one year, from March 2020 through February 2021, while the LUMCON was also deployed in March 2020 but Hurricane Zeta made landfall in Louisiana in October 2020 causing substantial damage to the dock at which the WIZ was deployed, delaying the redeployment of the sensor.

WIZ before deployment at Shell Point

The RECON Shell Point location is in the lower estuary where phytoplankton are thought to be nitrogen-limited for most of the year. The site is also downstream of an urbanized tidal watershed with over 372 miles of canals and largely residential land use that is under the Caloosahatchee Estuary Watershed Basin Management Action Plan (BMAP) which sets total maximum daily loads for total nitrogen.

“Enhanced nitrate monitoring is of great importance in this system,” said Milbrandt.

What’s Needed for Integration

By testing the integration of these sensors into existing water quality monitoring programs, the study highlighted the need to address full interoperability with non-proprietary datalogger systems and ongoing needs for more site-specific calibrations and post-hoc corrections.

“Collecting continuous nutrient data within existing monitoring systems like RECON is challenging because of the complicated nature of mixing reagents and standards in a self-contained system,” explained Milbrandt. “It requires development of new communication protocols, such as when to apply power and when to turn on pumps, and new field preparation techniques for deploying a sensor in a highly fouling marine environment.” 

SCCF Marine Lab Manager A.J. Martignette and former Research Assistant Sierra Greene also contributed to the study which was funded by National Oceanic and Atmospheric Administration (NOAA) via the Alliance for Coastal Technologies and the Gulf of Mexico Coastal Ocean Observing System (GCOOS). Read the full study.


RECON was established in 2007 to understand the dynamic and changing conditions in the Caloosahatchee partly caused by extreme freshwater releases from Lake Okeechobee and the Caloosahatchee watershed.

Considered to be one of the most comprehensive monitoring systems in the Gulf of Mexico, RECON measures key water quality parameters such as: temperature, salinity, dissolved oxygen, depth, CDOM (chromophoric dissolved organic matter), chlorophyll a, and turbidity.


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