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2020 Pensacola Bay LAKEWATCH Report

2020 LAKEWATCH Water Quality Update

Escambia County Florida

Citizen scientists monitoring water quality on Bayou Texar.
Photo: Marine Science Academy Washington High School

LAKEWATCH is a citizen science water quality volunteer program where residents from across the state monitoring nutrients and chlorophyll a levels within their local lakes.  As many know, excessive nutrients can lead to algal blooms, which can lead to low levels of dissolved oxygen in water ways, which can lead to fish kills.

Over time, the program included coastal estuaries monitoring for the same nutrients and chlorophyll a indicators.  In Escambia County, we currently have five volunteers monitoring one of five assigned bodies of water.  Our volunteer for Bayou Grande recently had to jump off, so we are looking for a new one there – and we have been given permission to add a volunteer for Escambia Bay.

 

These dedicated volunteers venture out to their three stations once every other month to collect water samples, filter water for chlorophyll a analysis, and measure the water clarity.  Some waterways have been monitored for a longer period of time than others.  Below are the results of the geometric means for their samples.

 

Waterway # of years sampled Range Total

Phosphorus

(µg/L)

Range Total Nitrogen

(µg/L)

Range of Chlorophyll a

(µg/L)

Water Clarity

(feet)

Salinity

(‰)

Trends over time
Bayou Texar 13 17-18 596-797 6-8 3.5-3.8 7-10 Phosphorus is declining

Clarity is improving

Bayou Grande 7 15-17 298-319 4-5 4.3-5.4 14-17 Clarity improving at station 1
Bayou Chico 6 23-30 354-585 9-19 3.0-4.6 6-9 No trends
Lower Perdido Bay 6 15-16 343-346 5 5.3-6.2 14-15 No trends
Upper Pensacola

Bay

1 17-22 270-380 5-11 4.8-6.5 No data yet Just started
Big Lagoon Began this year
Escambia Bay Seeking volunteer

 

TRENDS AND COMMENTS

1)      Phosphorus is not a nutrient we typically have and issue with locally.  That said, you will notice it is higher in Bayou Chico than other bodies of water.  There has also been a downward trend in the amount of total phosphorus in Bayou Texar over the last 13 years.

2)      Nitrogen is an issue and has been for a while.  Many of the large fish kills we experienced in our bayous during the 1970s were the results of excessive nutrients – in our case, nitrogen.  These fish kills are basically non-existent now.  Most bodies of water have total nitrogen values running between 300 and 400 µg/L, but Bayou Texar’s values have run between 500 and 800.  We do have data from a volunteer who monitored Texar between 2000-2002 and at that time the numbers ran between 359 and 406 – so there has been a significant increase in nitrogen over the last 20 years in Texar.  There is a need to reduce these numbers and there are things that all citizens can do to help.  For suggestions visit your County Extension website or contact your local Sea Grant Agent at the county extension office.

3)      If nutrients begin to trigger an algal bloom, you will notice this with increasing chlorophyll a values.  Chlorophyll a is a common pigment used by plants to photosynthesize.  To obtain these values, LAKEWATCH volunteers collect and filter samples of water for phytoplankton.  The filtered samples are then sent to the LAKEWATCH lab in Gainesville, with the other water samples, and analyzed by extracting the chlorophyll from the phytoplankton cells.  High chlorophyll numbers are a proxy for high phytoplankton numbers.  Most bodies of water run between 5-10 µg/L.  But Bayou Chico runs higher at 9-19 µg/L.  Though higher chlorophyll a values exist, fish kills are still rare in the bayou.  In recent years there have been a couple of kills in the middle of summer.  Though the chlorophyll is high, it could very well be extreme warm waters that time of year.  Warm water holds less dissolved oxygen than cooler waters.

4)      Poor water clarity can be caused by a variety of things – including algal blooms.  But it also may by sediment driven after a heavy rain, or from a construction site.  So, water clarity is one of the metrics LAKEWATCH volunteers measure while out there.  This is done by lowering a secchi into the water.  This is a circular piece of white plastic lowered until you no longer see it.  You then measure the length of the line in the water.  As one might expect, we would like to see an increase in water clarity over time.  One cause of seagrass loss is lower water clarity.  Our data shows the clarity of the water in the local bayous runs between 3-5 feet, the bays are better at 5-6 feet.  These data also show that one station in Bayou Grande, and all of them in Bayou Texar, have been improving over time.  This is good.

5)      If you not familiar with the term salinity it is the amount of dissolved solids in the water – how “salty” is the water?  Seawater is usually around 35‰ – you would not expect that in the bays and bayous.  Here tidal creeks and rivers bring freshwater loads into the system lowering the salinity in what we call brackish conditions.  The two primary seagrasses of the lower bay, and marine creatures like sea urchins and bay scallop, like the estuaries to be on the saltier side – say 20-30 ‰.  The lowering of salinity can decrease the abundance of some of these creatures and can be an indication of stormwater run-off issues.  Bayou’s Texar and Chico run between 5-10‰ but Bayou Grande is a little more saline.  You would expect the bays to be bit higher.  We have just begun monitoring Pensacola Bay, so do not have enough data to report this year, but lower Perdido Bay seems low.  It is believed that Perdido Bay in general is less saline than Pensacola Bay or Santa Rosa Sound and these numbers are not that alarming.

Lakewatch is a UF IFAS citizen science volunteer program.

We do appreciate our LAKEWATCH volunteers and the time they commit to collecting these samples for us.

 

Bayou Texar                     Alex Almario

Bayou Grande                 Julie Burger

Bayou Chico                     Jerri Johnson

Lower Perdido Bay          Bob Jackson

Upper Pensacola Bay     Caryn Ciesla

Big Lagoon                        Don Loerch

Escambia Bay                   open

 

If you have questions about the program or the data, contact Rick O’Connor at the Escambia County Extension Office – (850) 475-5230 ext.111.