Report Date - February 27th to March 5th, 2023

Project Name: Florida Department of Environmental Protection Grant INVO14: Remote Sensing of Harmful Algal Blooms in the Indian River Lagoon and Connected Waterways in Brevard County

Prepared By: Andrew Kamerosky and Rachel Scime

For the week of February 27th, 2023, to March 5th, 2023, there was a general increase in HAB activity from the previous week, with the Southern Mosquito Lagoon and South-North Indian River Lagoon experiencing the largest increases. There were 2 useable Sentinel-2 scenes and 6 Sentinel-3 scenes during this period.

Table 1 - Sentinel 3 estimated ChlA percent change for the week of February 27, 2023, to March 5, 2023, by IRL Basin.

The availability and usability of satellite imagery is contingent upon both the satellite being overhead and low cloud cover. The orbits of the Sentinel satellites will on occasion cover a portion of the Indian River Lagoon. Likewise, cloud cover can also result in only portions of the Indian River Lagoon (IRL) being visible. Table 2 below lists the availability of Sentinel imagery and its usability for Harmful Algal Bloom (HAB) analysis.

Table 2 - Sentinel 2 and 3 imagery availability for February 27th-March 5th, 2023

N - Imagery Not Available

Y - C - Imagery Available, Cannot Use Due to Cloud Cover

Y - P - Imagery Available, Only Partial Imagery of IRL

Y - G - Imagery Available, No Issues Over the IRL

27 February 2023 - Sentinel 3A

01 March 2023 - Sentinel 2B

01 March 2023 - Sentinel 3B

02 March 2023 - Sentinel 3A

02 March 2023 - Sentinel 3B

03 March 2023 - Sentinel 3A

05 March 2023 - Sentinel 3B

Two scenes from Sentinel 2 were usable for detection of HAB activity from February 27th, 2023, to March 5th, 2023. The following analysis focused on the scenes from February 27th and March 1st. Data from the Southern Mosquito Lagoon, Northern-North IRL, and Central-North IRL were not available on March 1st. (Figure 1, Figure 2)

Figure 1 - Sentinel 2 estimated Chlorophyll A (ChlA) Levels in Micrograms/Liter (µg/L) for February 27, 2023, over sections of the Mosquito Lagoon (ML), Indian River Lagoon (IRL), and Banana River (BR). The box plot represents the range of estimated ChlA values for each Basin, with the boxes showing the second quartile, median, and third quartile, and the whiskers representing the first and fourth quartiles.

Figure 2 - Sentinel 2 estimated Chlorophyll A (ChlA) Levels in Micrograms/Liter (µg/L) for March 1, 2023, over sections of the Mosquito Lagoon (ML), Indian River Lagoon (IRL), and Banana River (BR). The box plot represents the range of estimated ChlA values for each Basin, with the boxes showing the second quartile, median, and third quartile, and the whiskers representing the first and fourth quartiles.

Six scenes from Sentinel 3 were usable for detection of HAB activity from February 27th, 2023, to March 5th, 2023. The following analysis focuses on the scenes from February 27th and March 5th (Figure 3, Figure 4).

Figure 3 - Sentinel 3 estimated Chlorophyll A (ChlA) Levels in Micrograms/Liter (µg/L) for February 27, 2023, over sections of the Mosquito Lagoon (ML), Indian River Lagoon (IRL), and Banana River (BR). The box plot represents the range of estimated ChlA values for each Basin, with the boxes showing the second quartile, median, and third quartile, and the whiskers representing the first and fourth quartiles.

Figure 4 - Sentinel 3 estimated Chlorophyll A (ChlA) Levels in Micrograms/Liter (µg/L) for March 5, 2023, over sections of the Mosquito Lagoon (ML), Indian River Lagoon (IRL), and Banana River (BR). The box plot represents the range of estimated ChlA values for each Basin, with the boxes showing the second quartile, median, and third quartile, and the whiskers representing the first and fourth quartiles.

SJRWMD IRL Continuous Monitoring Stations

The St. John River Water Management District (SJRWMD) Continuous Monitoring (CM) stations measured generally stable Chlorophyll Reflective Fluorescence Units (RFU), with 3 of 5 stations experiencing an increase. (Figure 5, Table 3). 

Current and historical data are added to the SJRWMD’s database continuously; subsequent visits may reflect such additions or revisions. SJRWMD provides no warranty as to the accuracy, reliability, or completeness of these data.

Figure 5 - St Johns River Water Management District (SJRWMD) Indian River Lagoon Continuous Monitoring Station Relative Chlorophyll A (ChlA) readings from February 27th-March 5th, 2023, as described in Table 3.

Below are the estimated ChlA levels measured by SJRWMD continuous monitoring stations and Sentinel 3 within a radius of 0.75 miles (1.2 km) of the SJRWMD continuous monitoring stations for February 27th through March 5th. The Continuous Monitoring Station data is reported hourly by SJRWMD and this report provides the 95th percentile of RFU for a given day. 

Table 3 - St Johns River Water Management District (SJRWMD) Indian River Lagoon Continuous Monitoring Station Relative Chlorophyll A (ChlA) Relative Fluorescence from February 27th-March 5th, 2023.

   Figure 6. SJRWMD Continuous Monitoring stations and IRL Basins used for S2 and S3 analysis. 

Methods

HAB’s observed by this project are defined as over 80 Micrograms/Liter (µg/L) Chlorophyll A (ChlA) (as estimated by a calibrated Normalized Difference Chlorophyll Index (NDCI)) and persistent across the week in review. The algorithms that transform the NDCI index value to estimated ChlA concentrations were developed using a second-order polynomial equation. The Sentinel 2 (S2) equation has a Root Square (R2) of 0.81 with a Root Mean Square Error (RMSE) of 14.14 ug/L of ChlA. The Sentinel 3 (S3) equation has an R2 of 0.92 and an RMSE of 9.92 ug/L ChlA. The RMSE is a measure of the accuracy of a model in estimating values, ChlA in this instance, where a lower value is indicative of higher accuracy. It does not identify if the model consistently over or underestimates the modeled values. The equations are below:

• S2 Estimated ChlA = 297.36(NDCI)2 + 313.98(NDCI) + 36.152

• S3 Estimated ChlA = 437.07(NDCI)2 + 348.98(NDCI) + 33.928

Want to be in the know about other Save Our Indian River Lagoon Plan projects and progress?

Sign up for our monthly Newsletter Emails

Did you receive this email from someone else and would like to get your own weekly HAB notices?

Sign up for weekly HAB Emails