Weekly Indian River Lagoon

Harmful Algal Bloom Observations in

Brevard County Using Remote Sensing

Report Date - October 07 to October 13, 2024

Prepared By: Colby Holbrook, Andrew Kamerosky

Summary of Harmful Algal Bloom (HAB) Activity

For the week of October 7th, 2024, the estimated median Chlorophyll A (ChlA) in the Indian River Lagoon (IRL) increased across all observable basins. Imagery from October 5th was compared to October 12th (Table 1). ChlA within the Central Banana River Lagoon (C-BRL) on October 5th and Southern Banana River Lagoon (S-BRL) on October 12th could not be estimated due to cloud cover.


All observable basins ended the week within low bloom conditions of 6 to 20 µg/L.



For additional analysis, please visit our online web map.

European Space Agency Sentinel Satellite Estimated Chlorophyll A

Figure 1 - Processed Sentinel-3 imagery for October 05, 2024

Figure 2 - Processed Sentinel-3 imagery for October 12, 2024

Table 1 - Sentinel-3 estimated median ChlA in µg/L and percent change between October 05 to October 12, 2024, by IRL Basin. Basins without data were assigned ND.

Basin

October 05 Median ChlA

October 12 Median ChlA

Change in Median ChlA

Percent Change

SML

2.8

7.0

4.2

153%

N-NIRL

7.3

11.0

3.7

51%

C-NIRL

8.7

13.8

5.2

60%

N-BRL

9.8

12.8

3.0

31%

C-BRL

ND

9.7

ND

ND

S-BRL

2.2

ND

ND

ND

S-NIRL

4.5

6.8

2.3

51%

N-CIRL

2.3

6.9

4.6

199%

Methods

HABs observed by this project are defined as the condition when Chlorophyll A (ChlA) exceeds 80 Micrograms/Liter (µg/L) as estimated by a calibrated Normalized Difference Chlorophyll Index (NDCI)) and persistent over the week. 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. 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

   Figure 7 - SJRWMD Continuous Monitoring stations and IRL Basins used for S2 and S3 analysis. 

Use Our HAB Tool

Want to look at more detailed data, view a specific day, or compare days over time? Our online HAB Viewer Tool has additional graphs and will let you select days and even compare different days using the slider viewer tool.


Algae Bloom Viewer Tool

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

Visit our Website
Facebook  Instagram  YouTube