Funding & Acknowledgements

The data used in this analysis is from the Export Standardized Tables in the SEACAR Data Discovery Interface (DDI). Documents and information available through the SEACAR DDI are owned by the data provider(s) and users are expected to provide appropriate credit following accepted citation formats. Users are encouraged to access data to maximize utilization of gained knowledge, reducing redundant research and facilitating partnerships and scientific innovation.

With respect to documents and information available from SEACAR DDI, neither the State of Florida nor the Florida Department of Environmental Protection makes any warranty, expressed or implied, including the warranties of merchantability and fitness for a particular purpose arising out of the use or inability to use the data, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights.

This report was funded in part, through a grant agreement from the Florida Department of Environmental Protection, Florida Coastal Management Program, by a grant provided by the Office for Coastal Management under the Coastal Zone Management Act of 1972, as amended, National Oceanic and Atmospheric Administration. The views, statements, findings, conclusions and recommendations expressed herein are those of the author(s) and do not necessarily reflect the views of the State of Florida, NOAA or any of their sub agencies.

Published: 2025-10-08

Threshold Filtering

Threshold filters, following the guidance of Florida Department of Environmental Protection’s (FDEP) Division of Environmental Assessment and Restoration (DEAR) are used to exclude specific results values from the SEACAR Analysis. Based on the threshold filters, Quality Assurance / Quality Control (QAQC) Flags are inserted into the SEACAR_QAQCFlagCode and SEACAR_QAQC_Description columns of the export data. The Include column indicates whether the QAQC Flag will also indicate that data are excluded from analysis. No data are excluded from the data export, but the analysis scripts can use the Include column to exclude data (1 to include, 0 to exclude).

Continuous Water Quality threshold values
Parameter Name Units Low Threshold High Threshold
Dissolved Oxygen mg/L -0.000001 50
Dissolved Oxygen Saturation % -0.000001 500
Salinity ppt -0.000001 70
Turbidity NTU -0.000001 4000
Water Temperature Degrees C -5.000000 45
pH None 2.000000 14
Discrete Water Quality threshold values
Parameter Name Units Low Threshold High Threshold
Ammonia, Un-ionized (NH3) mg/L - -
Ammonium, Filtered (NH4) mg/L - -
Chlorophyll a, Corrected for Pheophytin ug/L - -
Chlorophyll a, Uncorrected for Pheophytin ug/L - -
Colored Dissolved Organic Matter PCU - -
Dissolved Oxygen mg/L -0.000001 25
Dissolved Oxygen Saturation % -0.000001 310
Fluorescent Dissolved Organic Matter QSE - -
Light Extinction Coefficient m^-1 - -
NO2+3, Filtered mg/L - -
Nitrate (NO3) mg/L - -
Nitrite (NO2) mg/L - -
Nitrogen, organic mg/L - -
Phosphate, Filtered (PO4) mg/L - -
Salinity ppt -0.000001 70
Secchi Depth m 0.000001 50
Specific Conductivity mS/cm 0.005000 100
Total Kjeldahl Nitrogen mg/L - -
Total Nitrogen mg/L - -
Total Nitrogen mg/L - -
Total Phosphorus mg/L - -
Total Suspended Solids mg/L - -
Turbidity NTU - -
Water Temperature Degrees C 3.000000 40
pH None 2.000000 13
Quality Assurance Flags inserted based on threshold checks listed in Table 1 and 2
SEACAR QAQC Description Include SEACAR QAQCFlagCode
Exceeds maximum threshold 0 2Q
Below minimum threshold 0 4Q
Within threshold tolerance 1 6Q
No defined thresholds for this parameter 1 7Q

Value Qualifiers

Value qualifier codes included within the data are used to exclude certain results from the analysis. The data are retained in the data export files, but the analysis uses the Include column to filter the results.

STORET and WIN value qualifier codes

Value qualifier codes from STORET and WIN data are examined with the database and used to populate the Include column in data exports.

Value Qualifier codes excluded from analysis
Qualifier Source Value Qualifier Include MDL Description
STORET-WIN H 0 0 Value based on field kit determination; results may not be accurate
STORET-WIN J 0 0 Estimated value
STORET-WIN V 0 0 Analyte was detected at or above method detection limit
STORET-WIN Y 0 0 Lab analysis from an improperly preserved sample; data may be inaccurate

Discrete Water Quality Value Qualifiers

The following value qualifiers are highlighted in the Discrete Water Quality section of this report. An exception is made for Program 476 - Charlotte Harbor Estuaries Volunteer Water Quality Monitoring Network and data flagged with Value Qualifier H are included for this program only.

H - Value based on field kit determiniation; results may not be accurate. This code shall be used if a field screening test (e.g., field gas chromatograph data, immunoassay, or vendor-supplied field kit) was used to generate the value and the field kit or method has not been recognized by the Department as equivalent to laboratory methods.

I - The reported value is greater than or equal to the laboratory method detection limit but less than the laboratory practical quantitation limit.

Q - Sample held beyond the accepted holding time. This code shall be used if the value is derived from a sample that was prepared or analyzed after the approved holding time restrictions for sample preparation or analysis.

S - Secchi disk visible to bottom of waterbody. The value reported is the depth of the waterbody at the location of the Secchi disk measurement.

U - Indicates that the compound was analyzed for but not detected. This symbol shall be used to indicate that the specified component was not detected. The value associated with the qualifier shall be the laboratory method detection limit. Unless requested by the client, less than the method detection limit values shall not be reported

Systemwide Monitoring Program (SWMP) value qualifier codes

Value qualifier codes from the SWMP continuous program are examined with the database and used to populate the Include column in data exports. SWMP Qualifier Codes are indicated by QualifierSource=SWMP.

SWMP Value Qualifier codes
Qualifier Source Value Qualifier Include Description
SWMP -1 1 Optional parameter not collected
SWMP -2 0 Missing data
SWMP -3 0 Data rejected due to QA/QC
SWMP -4 0 Outside low sensor range
SWMP -5 0 Outside high sensor range
SWMP 0 1 Passed initial QA/QC checks
SWMP 1 0 Suspect data
SWMP 2 1 Reserved for future use
SWMP 3 1 Calculated data: non-vented depth/level sensorcorrection for changes in barometric pressure
SWMP 4 1 Historical: Pre-auto QA/QC
SWMP 5 1 Corrected data

Water Column

The water column habitat extends from the water’s surface to the bottom sediments, and it’s where fish, dolphins, crabs and people swim! So much life makes its home in the water column that the health of marine and coastal ecosystems, as well as human economies, depend on the condition of this vulnerable habitat. Local patterns of rainfall, temperature, winds and currents can rapidly change the condition of the water column, while global influences such as El Niño/La Niña, large-scale fluctuation in sea temperatures and climate change can have long-term effects. Inputs from the prosperity of our day-to-day lives including farming, mining and forestry, and emissions from power generation, automobiles and water treatment can also alter the health of the water column. Acting alone or together, each input can have complex and lasting effects on habitats and ecosystems.


SEACAR evaluates water column health with several essential parameters. These include nutrient surveys of nitrogen and phosphorus, and water quality assessments of salinity, dissolved oxygen, pH, and water temperature. Water clarity is evaluated with Secchi depth, turbidity, levels of chlorophyll a, total suspended solids, and colored dissolved organic matter. Additionally, the richness of nekton is indicated by the abundance of free-swimming fishes and macroinvertebrates like crabs and shrimps.

Seasonal Kendall-Tau Analysis

Indicators must have a minimum of five to ten years, depending on the habitat, of data within the geographic range of the analysis to be included in the analysis. Ten years of data are required for discrete parameters, and five years of data are required for continuous parameters. If there are insufficient years of data, the number of years of data available will be noted and labeled as “insufficient data to conduct analysis”. Further, for the preferred Seasonal Kendall-Tau test, there must be data from at least two months in common across at least two consecutive years within the RCP managed area being analyzed. Values that pass both of these tests will be included in the analysis and be labeled as Use_In_Analysis = TRUE. Any that fail either test will be excluded from the analyses and labeled as Use_In_Analysis = FALSE. The points for all Water Column plots displayed in this section are monthly averages. Trend significance will be denoted as “Significant Trend” (when p < 0.05), or “Non-significant Trend” (when p >= 0.05). Any parameters with insufficient data to perform Seasonal Kendall-Tau test will have their monthly averages plotted without a corresponding trend line.

Water Quality - Discrete

The following files were used in the discrete analysis:

  • Combined_WQ_WC_NUT_Chlorophyll_a_corrected_for_pheophytin-2025-Sep-04.txt

  • Combined_WQ_WC_NUT_Chlorophyll_a_uncorrected_for_pheophytin-2025-Sep-04.txt

  • Combined_WQ_WC_NUT_Colored_dissolved_organic_matter_CDOM-2025-Sep-04.txt

  • Combined_WQ_WC_NUT_Dissolved_Oxygen-2025-Sep-04.txt

  • Combined_WQ_WC_NUT_Dissolved_Oxygen_Saturation-2025-Sep-04.txt

  • Combined_WQ_WC_NUT_pH-2025-Sep-04.txt

  • Combined_WQ_WC_NUT_Salinity-2025-Sep-04.txt

  • Combined_WQ_WC_NUT_Secchi_Depth-2025-Sep-04.txt

  • Combined_WQ_WC_NUT_Total_Nitrogen-2025-Sep-04.txt

  • Combined_WQ_WC_NUT_Total_Phosphorus-2025-Sep-04.txt

  • Combined_WQ_WC_NUT_Total_Suspended_Solids_TSS-2025-Sep-04.txt

  • Combined_WQ_WC_NUT_Turbidity-2025-Sep-04.txt

  • Combined_WQ_WC_NUT_Water_Temperature-2025-Sep-04.txt

Chlorophyll a, Corrected for Pheophytin - Discrete

Seasonal Kendall-Tau Trend Analysis

Scatter plot of monthly average levels of chlorophyll a, corrected for pheophytin, over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only laboratory-analyzed chlorophyll a (triangles) is included in the plot.
Scatter plot of monthly average levels of chlorophyll a, corrected for pheophytin, over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only laboratory-analyzed chlorophyll a (triangles) is included in the plot.
Seasonal Kendall-Tau Trend Analysis for Chlorophyll a, Corrected for Pheophytin
Activity Type Statistical Trend Sample Count Years with Data Period of Record Median tau Sen Intercept Sen Slope p
Lab Significantly decreasing trend 2889 21 2001 - 2025 3.14 -0.1821 6.3405 -0.1275 0.0002

Monthly average chlorophyll a, corrected for pheophytin, decreased by 0.13 µg/L per year, indicating an increase in water clarity.

Map showing location of discrete water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Map showing location of discrete water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Programs contributing data for Chlorophyll a, Corrected for Pheophytin
ProgramID N_Data YearMin YearMax
5002 1595 2001 2025
476 658 2008 2025
513 647 2017 2025
5028 17 2024 2025

Program names:

476 - Charlotte Harbor Estuaries Volunteer Water Quality Monitoring Network1
513 - Coastal Charlotte Harbor Monitoring Network2
5002 - Florida STORET / WIN3
5028 - Charlotte Harbor Aquatic Preserves Monthly Water Quality Program4

Chlorophyll a, Uncorrected for Pheophytin - Discrete

Seasonal Kendall-Tau Trend Analysis

Scatter plot of monthly average levels of chlorophyll a, uncorrected for pheophytin, over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only laboratory-analyzed chlorophyll a (triangles) is included in the plot.
Scatter plot of monthly average levels of chlorophyll a, uncorrected for pheophytin, over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only laboratory-analyzed chlorophyll a (triangles) is included in the plot.
Seasonal Kendall-Tau Trend Analysis for Chlorophyll a, Uncorrected for Pheophytin
Activity Type Statistical Trend Sample Count Years with Data Period of Record Median tau Sen Intercept Sen Slope p
Lab Significantly decreasing trend 2469 29 1997 - 2025 4.81 -0.1221 6.7768 -0.0593 0.0074

Monthly average chlorophyll a, uncorrected for pheophytin, decreased by 0.06 µg/L per year, indicating an increase in water clarity.

Map showing location of discrete water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Map showing location of discrete water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Programs contributing data for Chlorophyll a, Uncorrected for Pheophytin
ProgramID N_Data YearMin YearMax
5002 1589 1997 2025
476 707 1998 2025
514 165 2000 2009
3 40 2001 2010
5028 23 2024 2025
103 20 2000 2015
95 7 2003 2010
115 6 2000 2004
118 5 2000 2010
479 2 2002 2002

Program names:

3 - Atlantic Oceanographic and Meteorological Laboratory (AOML) South Florida Program Synoptic Shipboard Surveys5
95 - Harmful Algal Bloom Marine Observation Network6
103 - EPA STOrage and RETrieval Data Warehouse (STORET)/WQX7
115 - Environmental Monitoring Assessment Program8
118 - National Aquatic Resource Surveys, National Coastal Condition Assessment9
476 - Charlotte Harbor Estuaries Volunteer Water Quality Monitoring Network1
479 - Southwest Florida Water Management District - Water Quality Monitoring10
514 - Florida LAKEWATCH Program11
5002 - Florida STORET / WIN3
5028 - Charlotte Harbor Aquatic Preserves Monthly Water Quality Program4

Colored Dissolved Organic Matter - Discrete

Seasonal Kendall-Tau Trend Analysis

Scatter plot of monthly average colored dissolved organic matter (CDOM) over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only laboratory-analyzed CDOM (triangles) is included in the plot.
Scatter plot of monthly average colored dissolved organic matter (CDOM) over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only laboratory-analyzed CDOM (triangles) is included in the plot.
Seasonal Kendall-Tau Trend Analysis for Colored Dissolved Organic Matter
Activity Type Statistical Trend Sample Count Years with Data Period of Record Median tau Sen Intercept Sen Slope p
Lab No significant trend 1201 17 2001 - 2025 11.7 -0.074 16.5842 -0.2248 0.099

Colored dissolved organic matter showed no detectable trend between 2001 and 2025.

Map showing location of discrete water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Map showing location of discrete water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Programs contributing data for Colored Dissolved Organic Matter
ProgramID N_Data YearMin YearMax
513 647 2017 2025
476 294 2017 2025
5002 212 2018 2025
514 49 2001 2009
479 2 2002 2002

Program names:

476 - Charlotte Harbor Estuaries Volunteer Water Quality Monitoring Network1
479 - Southwest Florida Water Management District - Water Quality Monitoring10
513 - Coastal Charlotte Harbor Monitoring Network2
514 - Florida LAKEWATCH Program11
5002 - Florida STORET / WIN3

Dissolved Oxygen - Discrete

Seasonal Kendall-Tau Trend Analysis

Scatter plot of monthly average dissolved oxygen over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only dissolved oxygen values measured in the field (circles) are included in the plot.
Scatter plot of monthly average dissolved oxygen over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only dissolved oxygen values measured in the field (circles) are included in the plot.
Seasonal Kendall-Tau Trend Analysis for Dissolved Oxygen
Activity Type Statistical Trend Sample Count Years with Data Period of Record Median tau Sen Intercept Sen Slope p
Field Significantly decreasing trend 72673 38 1971 - 2025 6.5 -0.1355 6.902 -0.0105 0.0001

Monthly average dissolved oxygen decreased by 0.01 mg/L per year.

Map showing location of discrete water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Map showing location of discrete water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Programs contributing data for Dissolved Oxygen
ProgramID N_Data YearMin YearMax
69 38226 1989 2024
5002 20717 1993 2025
479 11958 2001 2016
476 1121 1996 2025
95 397 1971 2018
513 297 2017 2025
118 32 2000 2020
115 27 2000 2004
5028 19 2024 2025
103 14 2015 2015

Program names:

69 - Fisheries-Independent Monitoring (FIM) Program12
95 - Harmful Algal Bloom Marine Observation Network6
103 - EPA STOrage and RETrieval Data Warehouse (STORET)/WQX7
115 - Environmental Monitoring Assessment Program8
118 - National Aquatic Resource Surveys, National Coastal Condition Assessment9
476 - Charlotte Harbor Estuaries Volunteer Water Quality Monitoring Network1
479 - Southwest Florida Water Management District - Water Quality Monitoring10
513 - Coastal Charlotte Harbor Monitoring Network2
5002 - Florida STORET / WIN3
5028 - Charlotte Harbor Aquatic Preserves Monthly Water Quality Program4

Dissolved Oxygen Saturation - Discrete

Seasonal Kendall-Tau Trend Analysis

Scatter plot of monthly average dissolved oxygen saturation over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only dissolved oxygen saturation values measured in the field (circles) are included in the plot.
Scatter plot of monthly average dissolved oxygen saturation over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only dissolved oxygen saturation values measured in the field (circles) are included in the plot.
Seasonal Kendall-Tau Trend Analysis for Dissolved Oxygen Saturation
Activity Type Statistical Trend Sample Count Years with Data Period of Record Median tau Sen Intercept Sen Slope p
Field Significantly increasing trend 930 16 1992 - 2025 86.1 0.3708 22.7546 2.1099 0

Monthly average dissolved oxygen saturation increased by 2.11% per year.

Map showing location of discrete water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Map showing location of discrete water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Programs contributing data for Dissolved Oxygen Saturation
ProgramID N_Data YearMin YearMax
5002 354 2012 2025
513 296 2020 2025
476 251 2016 2025
95 43 2011 2018
5028 21 2024 2025
102 6 1992 1992

Program names:

95 - Harmful Algal Bloom Marine Observation Network6
102 - National Status and Trends Mussel Watch13
476 - Charlotte Harbor Estuaries Volunteer Water Quality Monitoring Network1
513 - Coastal Charlotte Harbor Monitoring Network2
5002 - Florida STORET / WIN3
5028 - Charlotte Harbor Aquatic Preserves Monthly Water Quality Program4

pH - Discrete

Seasonal Kendall-Tau Trend Analysis

Scatter plot of monthly average pH over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only pH values measured in the field (circles) are included in the plot.
Scatter plot of monthly average pH over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only pH values measured in the field (circles) are included in the plot.
Seasonal Kendall-Tau Trend Analysis for pH
Activity Type Statistical Trend Sample Count Years with Data Period of Record Median tau Sen Intercept Sen Slope p
Field No significant trend 69372 38 1955 - 2025 7.9 0.02 7.8793 0.0002 0.5775

pH showed no detectable trend between 1955 and 2025.

Map showing location of discrete water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Map showing location of discrete water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Programs contributing data for pH
ProgramID N_Data YearMin YearMax
69 37775 1989 2024
5002 18013 1993 2025
479 11746 2001 2016
476 1154 1996 2025
95 365 1955 2018
513 297 2017 2025
115 27 2000 2004
5028 22 2024 2025
103 17 2015 2015

Program names:

69 - Fisheries-Independent Monitoring (FIM) Program12
95 - Harmful Algal Bloom Marine Observation Network6
103 - EPA STOrage and RETrieval Data Warehouse (STORET)/WQX7
115 - Environmental Monitoring Assessment Program8
476 - Charlotte Harbor Estuaries Volunteer Water Quality Monitoring Network1
479 - Southwest Florida Water Management District - Water Quality Monitoring10
513 - Coastal Charlotte Harbor Monitoring Network2
5002 - Florida STORET / WIN3
5028 - Charlotte Harbor Aquatic Preserves Monthly Water Quality Program4

Salinity - Discrete

Seasonal Kendall-Tau Trend Analysis

Scatter plot of monthly average salinity over time. If the time series included ten or more years of discrete observations, significant (blue) or non-significant (magenta) trend lines are also shown. Discrete salinity values derived from grab samples analyzed in the field (circles) or the laboratory (triangles) are both included in the plot.
Scatter plot of monthly average salinity over time. If the time series included ten or more years of discrete observations, significant (blue) or non-significant (magenta) trend lines are also shown. Discrete salinity values derived from grab samples analyzed in the field (circles) or the laboratory (triangles) are both included in the plot.
Seasonal Kendall-Tau Trend Analysis for Salinity
Activity Type Statistical Trend Sample Count Years with Data Period of Record Median tau Sen Intercept Sen Slope p
All Significantly decreasing trend 76014 50 1954 - 2025 26.635 -0.2754 32.9701 -0.1113 0

Monthly average salinity decreased by 0.11 ppt per year.

Map showing location of discrete water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Map showing location of discrete water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Programs contributing data for Salinity
ProgramID N_Data YearMin YearMax
69 38571 1989 2024
5002 18393 1995 2025
479 11924 2001 2016
513 5075 2001 2024
476 1149 1996 2025
95 802 1954 2018
3 42 2001 2010
115 27 2000 2004
118 26 2015 2020
5028 21 2024 2025
102 6 1992 1992

Program names:

3 - Atlantic Oceanographic and Meteorological Laboratory (AOML) South Florida Program Synoptic Shipboard Surveys5
69 - Fisheries-Independent Monitoring (FIM) Program12
95 - Harmful Algal Bloom Marine Observation Network6
102 - National Status and Trends Mussel Watch13
115 - Environmental Monitoring Assessment Program8
118 - National Aquatic Resource Surveys, National Coastal Condition Assessment9
476 - Charlotte Harbor Estuaries Volunteer Water Quality Monitoring Network1
479 - Southwest Florida Water Management District - Water Quality Monitoring10
513 - Coastal Charlotte Harbor Monitoring Network2
5002 - Florida STORET / WIN3
5028 - Charlotte Harbor Aquatic Preserves Monthly Water Quality Program4

Secchi Depth - Discrete

Seasonal Kendall-Tau Trend Analysis

Scatter plot of monthly average Secchi depth over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Secchi depth is only measured in the field (circles).
Scatter plot of monthly average Secchi depth over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Secchi depth is only measured in the field (circles).
Seasonal Kendall-Tau Trend Analysis for Secchi Depth
Activity Type Statistical Trend Sample Count Years with Data Period of Record Median tau Sen Intercept Sen Slope p
Field No significant trend 45800 32 1994 - 2025 -1.2 -0.0458 -1.3528 -0.0027 0.2074

Secchi depth showed no detectable trend between 1994 and 2025.

Map showing location of discrete water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Map showing location of discrete water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Programs contributing data for Secchi Depth
ProgramID N_Data YearMin YearMax
69 35556 1994 2024
479 5322 2001 2016
5002 3793 2003 2025
476 936 1996 2025
514 159 2000 2009
5028 19 2024 2025
103 13 1998 2020
513 7 2017 2024
115 5 2000 2004

Program names:

69 - Fisheries-Independent Monitoring (FIM) Program12
103 - EPA STOrage and RETrieval Data Warehouse (STORET)/WQX7
115 - Environmental Monitoring Assessment Program8
476 - Charlotte Harbor Estuaries Volunteer Water Quality Monitoring Network1
479 - Southwest Florida Water Management District - Water Quality Monitoring10
513 - Coastal Charlotte Harbor Monitoring Network2
514 - Florida LAKEWATCH Program11
5002 - Florida STORET / WIN3
5028 - Charlotte Harbor Aquatic Preserves Monthly Water Quality Program4

Total Nitrogen - Discrete

Total Nitrogen Calculation:

The logic for calculated Total Nitrogen was provided by Kevin O’Donnell and colleagues at FDEP (with the help of Jay Silvanima, Watershed Monitoring Section). The following logic is used, in this order, based on the availability of specific nitrogen components.

  1. TN = TKN + NO3O2;
  2. TN = TKN + NO3 + NO2;
  3. TN = ORGN + NH4 + NO3O2;
  4. TN = ORGN + NH4 + NO2 + NO3;
  5. TN = TKN + NO3;
  6. TN = ORGN + NH4 + NO3;

Additional Information:

  • Rules for use of sample fraction:
    • Florida Department of Environmental Protection (FDEP) report that if both “Total” and “Dissolved” components are reported, only “Total” is used. If the total is not reported, then the dissolved components are used as a best available replacement.
    • Total nitrogen calculations are done using nitrogen components with the same sample fraction, nitrogen components with mixed total/dissolved sample fractions are not used. In other words, total nitrogen can be calculated when TKN and NO3O2 are both total sample fractions, or when both are dissolved sample fractions. Future calculations of total nitrogen values may be based on components with mixed sample fractions.
  • Values inserted into data:
    • ParameterName = “Total Nitrogen”
    • SEACAR_QAQCFlagCode = “1Q”
    • SEACAR_QAQC_Description = “SEACAR Calculated”

Seasonal Kendall-Tau Trend Analysis

Scatter plot of monthly average total nitrogen over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only nitrogen values obtained from laboratory analyses (triangles) are included in the plot.
Scatter plot of monthly average total nitrogen over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only nitrogen values obtained from laboratory analyses (triangles) are included in the plot.
Seasonal Kendall-Tau Trend Analysis for Total Nitrogen
Activity Type Statistical Trend Sample Count Years with Data Period of Record Median tau Sen Intercept Sen Slope p
Lab Significantly increasing trend 9152 33 1993 - 2025 0.673 0.1102 0.5982 0.0034 0.0037

Monthly average total nitrogen increased by less than 0.01 mg/L per year.

Map showing location of discrete water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Map showing location of discrete water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Programs contributing data for Total Nitrogen
ProgramID N_Data YearMin YearMax
5002 5163 1993 2025
479 2134 2002 2016
476 988 1998 2025
513 644 2018 2025
514 169 2000 2009
103 37 2000 2006
5028 16 2024 2025
115 4 2000 2003

Program names:

103 - EPA STOrage and RETrieval Data Warehouse (STORET)/WQX7
115 - Environmental Monitoring Assessment Program8
476 - Charlotte Harbor Estuaries Volunteer Water Quality Monitoring Network1
479 - Southwest Florida Water Management District - Water Quality Monitoring10
513 - Coastal Charlotte Harbor Monitoring Network2
514 - Florida LAKEWATCH Program11
5002 - Florida STORET / WIN3
5028 - Charlotte Harbor Aquatic Preserves Monthly Water Quality Program4

Total Phosphorus - Discrete

Seasonal Kendall-Tau Trend Analysis

Scatter plot of monthly average total phosphorus over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only phosphorus values obtained from laboratory analyses (triangles) are included in the plot.
Scatter plot of monthly average total phosphorus over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only phosphorus values obtained from laboratory analyses (triangles) are included in the plot.
Seasonal Kendall-Tau Trend Analysis for Total Phosphorus
Activity Type Statistical Trend Sample Count Years with Data Period of Record Median tau Sen Intercept Sen Slope p
Lab No significant trend 7044 28 1998 - 2025 0.114 0.0601 0.1126 0.0005 0.1351

Total phosphorus showed no detectable trend between 1998 and 2025.

Map showing location of discrete water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Map showing location of discrete water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Programs contributing data for Total Phosphorus
ProgramID N_Data YearMin YearMax
5002 3017 2001 2025
479 2118 2002 2016
476 1079 1998 2025
513 653 2017 2025
514 169 2000 2009
103 30 2000 2015
5028 19 2024 2025
115 4 2000 2003

Program names:

103 - EPA STOrage and RETrieval Data Warehouse (STORET)/WQX7
115 - Environmental Monitoring Assessment Program8
476 - Charlotte Harbor Estuaries Volunteer Water Quality Monitoring Network1
479 - Southwest Florida Water Management District - Water Quality Monitoring10
513 - Coastal Charlotte Harbor Monitoring Network2
514 - Florida LAKEWATCH Program11
5002 - Florida STORET / WIN3
5028 - Charlotte Harbor Aquatic Preserves Monthly Water Quality Program4

Total Suspended Solids - Discrete

Seasonal Kendall-Tau Trend Analysis

Scatter plot of monthly average total suspended solids (TSS) over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only TSS values obtained from laboratory analyses (triangles) are included in the plot.
Scatter plot of monthly average total suspended solids (TSS) over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only TSS values obtained from laboratory analyses (triangles) are included in the plot.
Seasonal Kendall-Tau Trend Analysis for Total Suspended Solids
Activity Type Statistical Trend Sample Count Years with Data Period of Record Median tau Sen Intercept Sen Slope p
Lab No significant trend 7310 30 1996 - 2025 7.75 0.0496 8.5886 0.0412 0.1997

Total suspended solids showed no detectable trend between 1996 and 2025.

Map showing location of discrete water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Map showing location of discrete water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Programs contributing data for Total Suspended Solids
ProgramID N_Data YearMin YearMax
5002 4524 1996 2025
513 2571 2001 2025
479 2137 2002 2016
476 10 2016 2016

Program names:

476 - Charlotte Harbor Estuaries Volunteer Water Quality Monitoring Network1
479 - Southwest Florida Water Management District - Water Quality Monitoring10
513 - Coastal Charlotte Harbor Monitoring Network2
5002 - Florida STORET / WIN3

Turbidity - Discrete

Seasonal Kendall-Tau Trend Analysis

Scatter plot of monthly average turbidity over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only turbidity values measured in the laboratory (triangles) are included in the plot.
Scatter plot of monthly average turbidity over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only turbidity values measured in the laboratory (triangles) are included in the plot.
Seasonal Kendall-Tau Trend Analysis for Turbidity
Activity Type Statistical Trend Sample Count Years with Data Period of Record Median tau Sen Intercept Sen Slope p
Lab Significantly decreasing trend 12973 31 1995 - 2025 1.9 -0.1966 2.6915 -0.0278 0

Monthly average turbidity decreased by 0.03 NTU per year, indicating an increase in water clarity.

Map showing location of discrete water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Map showing location of discrete water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Programs contributing data for Turbidity
ProgramID N_Data YearMin YearMax
5002 8510 1995 2025
479 3386 2001 2016
513 2668 2001 2025
476 1122 1998 2025
95 6 2003 2003
103 2 2006 2006

Program names:

95 - Harmful Algal Bloom Marine Observation Network6
103 - EPA STOrage and RETrieval Data Warehouse (STORET)/WQX7
476 - Charlotte Harbor Estuaries Volunteer Water Quality Monitoring Network1
479 - Southwest Florida Water Management District - Water Quality Monitoring10
513 - Coastal Charlotte Harbor Monitoring Network2
5002 - Florida STORET / WIN3

Water Temperature - Discrete

Seasonal Kendall-Tau Trend Analysis

Scatter plot of monthly average water temperature over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only water temperature measurements taken in the field (circles) are included in the plot.
Scatter plot of monthly average water temperature over time. If the time series included ten or more years of discrete observations, a significant (blue) or non-significant (magenta) trend line is also shown. Only water temperature measurements taken in the field (circles) are included in the plot.
Seasonal Kendall-Tau Trend Analysis for Water Temperature
Activity Type Statistical Trend Sample Count Years with Data Period of Record Median tau Sen Intercept Sen Slope p
Field Significantly increasing trend 73705 50 1954 - 2025 26.1 0.1436 24.6886 0.016 0

Monthly average water temperature increased by 0.02°C per year.

Map showing location of discrete water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Map showing location of discrete water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Programs contributing data for Water Temperature
ProgramID N_Data YearMin YearMax
69 38576 1989 2024
5002 20996 1993 2025
479 11918 2001 2016
476 1151 1996 2025
95 722 1954 2018
513 297 2017 2025
115 27 2000 2004
5028 21 2024 2025
102 6 1992 1992

Program names:

69 - Fisheries-Independent Monitoring (FIM) Program12
95 - Harmful Algal Bloom Marine Observation Network6
102 - National Status and Trends Mussel Watch13
115 - Environmental Monitoring Assessment Program8
476 - Charlotte Harbor Estuaries Volunteer Water Quality Monitoring Network1
479 - Southwest Florida Water Management District - Water Quality Monitoring10
513 - Coastal Charlotte Harbor Monitoring Network2
5002 - Florida STORET / WIN3
5028 - Charlotte Harbor Aquatic Preserves Monthly Water Quality Program4

Water Quality - Continuous

The following files were used in the continuous analysis:

  • Combined_WQ_WC_NUT_cont_Dissolved_Oxygen_SW-2025-Sep-19.txt

  • Combined_WQ_WC_NUT_cont_Dissolved_Oxygen_Saturation_SW-2025-Sep-19.txt

  • Combined_WQ_WC_NUT_cont_pH_SW-2025-Sep-19.txt

  • Combined_WQ_WC_NUT_cont_Salinity_SW-2025-Sep-19.txt

  • Combined_WQ_WC_NUT_cont_Turbidity_SW-2025-Sep-19.txt

  • Combined_WQ_WC_NUT_cont_Water_Temperature_SW-2025-Sep-19.txt

Continuous monitoring locations in Gasparilla Sound-Charlotte Harbor Aquatic Preserve

Station overview for Continuous parameters by Program
ProgramID ProgramLocationID Years of Data Use in Analysis Parameters
7 02293252 4 FALSE Sal , TempW
7 02293254 4 FALSE Sal , TempW
512 CHEW1 2 FALSE DO , DOS , pH , Sal , Turb , TempW

Program names:

7 - National Water Information System14
512 - Charlotte Harbor Aquatic Preserves Continuous Water Quality Monitoring15

Map showing continuous water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. Sites marked as Use In Analysis (green) are featured in this report.
Map showing continuous water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. Sites marked as Use In Analysis (green) are featured in this report.

Dissolved Oxygen - Continuous

Scatter plot of monthly average dissolved oxygen over time at continuously monitored program locations. Each location is analyzed separately, with significant (blue) or non-significant (magenta) trend lines shown for time series that included five or more years of observations.
Scatter plot of monthly average dissolved oxygen over time at continuously monitored program locations. Each location is analyzed separately, with significant (blue) or non-significant (magenta) trend lines shown for time series that included five or more years of observations.
Seasonal Kendall-Tau Results for Dissolved Oxygen - All Stations
Station Statistical Trend Sample Count Years with Data Period of Record Median tau Sen Intercept Sen Slope p
CHEW1 Insufficient data to calculate trend 39706 2 2024 - 2025 6.4 - - - -

There was insufficient data to fit a model for one location.

Map showing location of dissolved oxygen continuous water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Map showing location of dissolved oxygen continuous water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.

Dissolved Oxygen Saturation - Continuous

Scatter plot of monthly average dissolved oxygen saturation over time at continuously monitored program locations. Each location is analyzed separately, with significant (blue) or non-significant (magenta) trend lines shown for time series that included five or more years of observations.
Scatter plot of monthly average dissolved oxygen saturation over time at continuously monitored program locations. Each location is analyzed separately, with significant (blue) or non-significant (magenta) trend lines shown for time series that included five or more years of observations.
Seasonal Kendall-Tau Results for Dissolved Oxygen Saturation - All Stations
Station Statistical Trend Sample Count Years with Data Period of Record Median tau Sen Intercept Sen Slope p
CHEW1 Insufficient data to calculate trend 39704 2 2024 - 2025 89.9 - - - -

There was insufficient data to fit a model for one location.

Map showing location of dissolved oxygen saturation continuous water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Map showing location of dissolved oxygen saturation continuous water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.

pH - Continuous

Scatter plot of monthly average pH over time at continuously monitored program locations. Each location is analyzed separately, with significant (blue) or non-significant (magenta) trend lines shown for time series that included five or more years of observations.
Scatter plot of monthly average pH over time at continuously monitored program locations. Each location is analyzed separately, with significant (blue) or non-significant (magenta) trend lines shown for time series that included five or more years of observations.
Seasonal Kendall-Tau Results for pH - All Stations
Station Statistical Trend Sample Count Years with Data Period of Record Median tau Sen Intercept Sen Slope p
CHEW1 Insufficient data to calculate trend 44990 2 2024 - 2025 7.9 - - - -

There was insufficient data to fit a model for one location.

Map showing location of ph continuous water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Map showing location of ph continuous water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.

Salinity - Continuous

Scatter plot of monthly average salinity over time at continuously monitored program locations. Each location is analyzed separately, with significant (blue) or non-significant (magenta) trend lines shown for time series that included five or more years of observations.
Scatter plot of monthly average salinity over time at continuously monitored program locations. Each location is analyzed separately, with significant (blue) or non-significant (magenta) trend lines shown for time series that included five or more years of observations.
Seasonal Kendall-Tau Results for Salinity - All Stations
Station Statistical Trend Sample Count Years with Data Period of Record Median tau Sen Intercept Sen Slope p
02293254 Insufficient data to calculate trend 1030 4 2011 - 2014 29.0 - - - -
02293252 Insufficient data to calculate trend 1002 4 2011 - 2014 30.0 - - - -
CHEW1 Insufficient data to calculate trend 48346 2 2024 - 2025 27.5 - - - -

There was insufficient data to fit a model for three locations.

Map showing location of salinity continuous water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Map showing location of salinity continuous water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.

Turbidity - Continuous

Scatter plot of monthly average turbidity over time at continuously monitored program locations. Each location is analyzed separately, with significant (blue) or non-significant (magenta) trend lines shown for time series that included five or more years of observations.
Scatter plot of monthly average turbidity over time at continuously monitored program locations. Each location is analyzed separately, with significant (blue) or non-significant (magenta) trend lines shown for time series that included five or more years of observations.
Seasonal Kendall-Tau Results for Turbidity - All Stations
Station Statistical Trend Sample Count Years with Data Period of Record Median tau Sen Intercept Sen Slope p
CHEW1 Insufficient data to calculate trend 33403 2 2024 - 2025 2 - - - -

There was insufficient data to fit a model for one location.

Map showing location of turbidity continuous water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Map showing location of turbidity continuous water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.

Water Temperature - Continuous

Scatter plot of monthly average water temperature over time at continuously monitored program locations. Each location is analyzed separately, with significant (blue) or non-significant (magenta) trend lines shown for time series that included five or more years of observations.
Scatter plot of monthly average water temperature over time at continuously monitored program locations. Each location is analyzed separately, with significant (blue) or non-significant (magenta) trend lines shown for time series that included five or more years of observations.
Seasonal Kendall-Tau Results for Water Temperature - All Stations
Station Statistical Trend Sample Count Years with Data Period of Record Median tau Sen Intercept Sen Slope p
02293254 Insufficient data to calculate trend 1041 4 2011 - 2014 27.0 - - - -
02293252 Insufficient data to calculate trend 1003 4 2011 - 2014 26.4 - - - -
CHEW1 Insufficient data to calculate trend 48352 2 2024 - 2025 26.7 - - - -

There was insufficient data to fit a model for three locations.

Map showing location of water temperature continuous water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.
Map showing location of water temperature continuous water quality sampling locations within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The bubble size on the maps above reflect the amount of data available at each sampling site.

Submerged Aquatic Vegetation

The data file used is: All_SAV_Parameters-2025-Sep-04.txt

Submerged aquatic vegetation (SAV) refers to plants and plant-like macroalgae species that live entirely underwater. The two primary categories of SAV inhabiting Florida estuaries are benthic macroalgae and seagrasses. They often grow together in dense beds or meadows that carpet the seafloor. Macroalgae include multicellular species of green, red and brown algae that often live attached to the substrate by a holdfast. They tend to grow quickly and can tolerate relatively high nutrient levels, making them a threat to seagrasses and other benthic habitats in areas with poor water quality. In contrast, seagrasses are grass-like, vascular, flowering plants that are attached to the seafloor by extensive root systems. Seagrasses occur throughout the coastal areas of Florida, including protected bays and lagoons as well as deeper offshore waters on the continental shelf. Seagrasses have taken advantage of the broad, shallow shelf and clear water to produce two of the most extensive seagrass beds anywhere in continental North America.

Parameters

Percent Cover measures the fraction of an area of seafloor that is covered by SAV, usually estimated by evaluating multiple small areas of seafloor. Percent cover is often estimated for total SAV, individual types of vegetation (seagrass, attached algae, drift algae) and individual species.

Frequency of Occurrence was calculated as the number of times a taxon was observed in a year divided by the number of sampling events, multiplied by 100. Analysis is conducted at the quadrat level and is inclusive of all quadrats (i.e., quadrats evaluated using Braun-Blanquet, modified Braun-Blanquet, and percent cover.”

Species

Turtle grass (Thalassia testudinum) is the largest of the Florida seagrasses, with longer, thicker blades and deeper root structures than any of the other seagrasses. It is considered a climax seagrass species.

Shoal grass (Halodule wrightii) is an early colonizer of vegetated areas and usually grows in water too shallow for other species except widgeon grass. It can often tolerate larger salinity ranges than other seagrass species. Shoal grass is characterized by thin, flat blades, that are narrower than turtle grass blades.

Manatee grass (Syringodium filiforme) is easily recognizable because its leaves are thin and cylindrical instead of the flat, ribbon-like form shared by many other seagrass species. The leaves can grow up to half a meter in length. Manatee grass is usually found in mixed seagrass beds or small, dense monospecific patches.

Widgeon grass (Ruppia maritima) grows in both fresh and salt water and is widely distributed throughout Florida’s estuaries in less saline areas, particularly in inlets along the east coast. This species resembles shoal grass in certain environments but can be identified by the pointed tips of its leaves.

Three species of Halophila spp. are found in Florida - Star grass (Halophila engelmannii), Paddle grass (Halophila decipiens), and Johnson’s seagrass (Halophila johnsonii). These are smaller, more fragile seagrasses than other Florida species and are considered ephemeral. They grow along a single long rhizome, with short blades. These species are not well-studied, although surveys are underway to define their ecological roles.

Notes

Star grass, Paddle grass, and Johnson’s seagrass will be grouped together and listed as Halophila spp. in the following managed areas. This is because several surveys did not specify to the species level:

  • Banana River Aquatic Preserve

  • Indian River-Malabar to Vero Beach Aquatic Preserve

  • Indian River-Vero Beach to Ft. Pierce Aquatic Preserve

  • Jensen Beach to Jupiter Inlet Aquatic Preserve

  • Loxahatchee River-Lake Worth Creek Aquatic Preserve

  • Mosquito Lagoon Aquatic Preserve

  • Biscayne Bay Aquatic Preserve

  • Florida Keys National Marine Sanctuary

Maps showing the temporal scope of SAV sampling sites within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve by Program name.
Maps showing the temporal scope of SAV sampling sites within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve by Program name.

Click here to view spatio-temporal plots on GitHub.

Sampling locations by Program:

Map showing SAV sampling sites within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The point size reflects the number of samples at a given sampling site.
Map showing SAV sampling sites within the boundaries of Gasparilla Sound-Charlotte Harbor Aquatic Preserve. The point size reflects the number of samples at a given sampling site.
Program Information for Submerged Aquatic Vegetation
ProgramID N-Data YearMin YearMax method Sample Locations
570 8663 1998 2024 Braun Blanquet 20

Program names:

570 - Charlotte Harbor Seagrass Monitoring16

Scatter plots of median percent cover of submerged aquatic vegetation over time by group. Plots for time series that included five or more years of observations show the estimated trend as a blue line.
Scatter plots of median percent cover of submerged aquatic vegetation over time by group. Plots for time series that included five or more years of observations show the estimated trend as a blue line.
Trends in median percent cover for various seagrass species in Gasparilla Sound-Charlotte Harbor Aquatic Preserve - simplified
Trends in median percent cover for various seagrass species in Gasparilla Sound-Charlotte Harbor Aquatic Preserve - simplified
Percent Cover Trend Analysis for Gasparilla Sound-Charlotte Harbor Aquatic Preserve
CommonName Trend Significance (0.05) Period of Record LME-Intercept LME-Slope p
Attached algae No significant trend 2007 - 2024 -11.375242 0.9118123 0.2571837
Drift algae No significant trend 1999 - 2024 8.352341 0.3703061 0.1797671
Shoal grass No significant trend 1998 - 2024 20.792400 -0.1247684 0.0762040
Star grass Insufficient data to calculate trend - - - -
No grass in quadrat Model did not fit the available data 1998 - 2024 - - -
Widgeon grass Model did not fit the available data 1998 - 2019 - - -
Manatee grass No significant trend 1998 - 2024 46.715525 -0.2566471 0.6220208
Turtle grass No significant trend 1998 - 2024 32.492916 -0.2224869 0.1353125
Total seagrass Significantly decreasing trend 1998 - 2024 25.252288 -0.1989083 0.0083591

An annual decrease in percent cover was observed for total seagrass (-0.2%). Manatee grass, shoal grass, turtle grass, attached algae, and drift algae showed no detectable change in percent cover. Trends in percent cover could not be evaluated for star grass due to insufficient data, and the model could not be fitted for widgeon grass.

Frequency of occurrence for various seagrass species in Gasparilla Sound-Charlotte Harbor Aquatic Preserve
Frequency of occurrence for various seagrass species in Gasparilla Sound-Charlotte Harbor Aquatic Preserve

SAV Water Column Analysis

The following parameters are available for Gasparilla Sound-Charlotte Harbor Aquatic Preserve within the SAV_WC_Report:

  • Colored Disolved Organic Matter

  • Chlorophyll a

  • Dissolved Oxygen

  • Dissolved Oxygen Saturation

  • pH

  • Salinity

  • Secchi Depth

  • Water Temperature

  • Total Nitrogen

  • Total Suspended Solids

  • Turbidity

Access the reports here: DRAFT_SAV_WC_Report_2024-11-20.pdf

Species list

Caulerpa mexicana1 Halodule wrightii1 Syringodium filiforme1
Caulerpa prolifera1 Halophila engelmannii1 Thalassia testudinum1
Caulerpa sertularioides1 No grass in quadrat1 Total seagrass1
Caulerpa spp.1 Ruppia maritima1 Caulerpa mexicana1
Drift algae1 Sargassum buxifolium1 Caulerpa prolifera1

1 - Submerged Aquatic Vegetation

References

1.
Florida Department of Environmental Protection (DEP); Office of Resilience and Coastal Protection (RCP); Charlotte Harbor Aquatic Preserves. Charlotte Harbor Estuaries Volunteer Water Quality Monitoring Network. (2024).
2.
Charlotte Harbor National Estuary Program (CHNEP). Coastal Charlotte Harbor Monitoring Network. (2024).
3.
Florida Department of Environmental Protection (DEP). Florida STORET / WIN. (2024).
4.
Florida Department of Environmental Protection (DEP); Office of Resilience and Coastal Protection (RCP); Charlotte Harbor Aquatic Preserves. Charlotte Harbor Aquatic Preserves Monthly Water Quality Program. (2024).
5.
National Oceanic and Atmospheric Administration (NOAA); Atlantic Oceanographic and Meterological Laboratory. Atlantic Oceanographic and Meteorological Laboratory (AOML) South Florida Program Synoptic Shipboard Surveys. (2024).
6.
Florida Fish and Wildlife Conservation Commission (FWC); Florida Fish and Wildlife Research Institute (FWRI). Harmful Algal Bloom Marine Observation Network. (2018).
7.
U.S. Environmental Protection Agency (EPA). EPA STOrage and RETrieval Data Warehouse (STORET)/WQX. (2023).
8.
U.S. Environmental Protection Agency (EPA); Office of Research and Development. Environmental Monitoring Assessment Program. (2004).
9.
U.S. Environmental Protection Agency (EPA); Office of Water; National Oceanic and Atmospheric Administration (NOAA); U.S. Geological Survey (USGS); U.S. Fish and Wildlife Service (USFWS); National Estuary Program (NEP); coastal states. National Aquatic Resource Surveys, National Coastal Condition Assessment. (2021).
10.
Southwest Florida Water Management District (SWFWMD). Southwest Florida Water Management District - Water Quality Monitoring. (2024).
11.
University of Florida (UF); Institute of Food and Agricultural Sciences. Florida LAKEWATCH Program. (2024).
12.
Florida Fish and Wildlife Conservation Commission (FWC). Fisheries-Independent Monitoring (FIM) Program. (2022).
13.
National Oceanic and Atmospheric Administration (NOAA); Center for Coastal Monitoring and Assessment. National Status and Trends Mussel Watch. (2000).
14.
U.S. Geological Survey (USGS). National Water Information System. (2024).
15.
Florida Department of Environmental Protection (DEP); Office of Resilience and Coastal Protection (RCP); Charlotte Harbor Aquatic Preserves. Charlotte Harbor Aquatic Preserves Continuous Water Quality Monitoring. (2024).
16.
Florida Department of Environmental Protection (DEP); Office of Resilience and Coastal Protection (RCP); Charlotte Harbor Aquatic Preserves. Charlotte Harbor Seagrass Monitoring. (2023).