2018 Seagrass Monitoring Report for Santa Rosa Sound and Big Lagoon

The seagrass commonly known as Shoal Grass.
Photo: Leroy Creswell

RELEVANCE

Studies show that acres of seagrass beds within the Pensacola Bay system declined during the 1950s and 1960s. Seagrasses are an important component of local fisheries; 80% of local commercial and recreational species use these habitats for at least part of their life cycle. The loss of seagrass is due to many factors. Excessive stormwater run-off decreases the salinity below the tolerance of some grass species and increases total suspended solids, which block needed sunlight. Excessive nutrients in the run-off can trigger blooms of drift algae, which again can block needed sunlight as well as compete for needed nutrients.

Since the 1970s, the community has made development changes that have reduce the amount of run-off reaching the bay. Though this has helped, more is needed to recover these habitats.

A study published in 2018, indicated that seagrass beds increased by 13% between 2010 and 2015.

Seagrass meadow
Photo: Virginia Sea Grant

 

RESPONSE

In 2017, the Center of Environmental Diagnostics and Bioremediation at the University of West Florida partnered with Florida Sea Grant to develop a citizen science monitoring program to continue monitoring seagrasses in Big Lagoon and Santa Rosa Sound.

 

Local residents, many who live on the water where seagrasses exist, volunteered for this project. Residents are trained on methods in April and conduct monthly surveys from May through October. 2018 was the first year to complete the full cycle.

 

Each body of water is divided into 1-nautical mile grids and one is assigned to a volunteer to monitor. There are 11 such grids in Big Lagoon and 55 in Santa Rosa Sound. Within each grid, the volunteer selects four locations to monitor. These four locations will be monitored each month during each monitoring season. Using snorkel, volunteers lay a 0.25 m2 PVC quadrat on the bottom, determine percent coverage of grass, which species of grass is present, percent coverage of drift algae, and note any marine animals within.

 

The volunteers also collect a water sample, which is analyzed in the lab of Dr. Jane Caffrey at UWF. These samples are analyzed for total suspended solids, selected nutrients, and chlorophyll a.

 

UWF students in Dr. Jane Caffrey’s lab visit some locations during the monitoring season to measure selected parameters using a YSI meter. Those selected parameters include: salinity, temperature, dissolved oxygen, and ph. Water clarity is monitored using a secchi disk.

 

 

RESULTS

14 volunteers participated in the 2018 surveys. Five of the 11 grids in Big Lagoon and six of the 55 in Santa Rosa Sound were surveyed; all of the SRS grids were between Midway and Gulf Breeze.

One volunteer surveyed a station in Old River north of Perdido Key. This station was between the Theo Baars Bridge and the state line.

  Body of Water # of samples Range of % coverage Mean of % coverage Species of seagrass
Seagrass % coverage Old River 5 50-85 % 71% All shoal grass
  Big Lagoon

 

8 48-73% 60% Mix of turtle and shoal grass; Widgeon grass appeared in Sep
  Santa Rosa Sound 4 55-100% 72% Mix of turtle and shoal grass; higher % of turtle grass than BL; Widgeon grass appeared in Sep
Drift Algae % coverage Old River 5 0-25% 8%  
  Big Lagoon 8 0-23% 6%

 

 
  Santa Rosa Sound 4 0-6% 2%  

 

 

UWF ENVIRONMENTAL RESULTS

 

Salinity

Salinity data from SRS between 2002 – 2005 ranged from 16-32 ‰; the mean ranged from 24-30‰

Salinity data from SRS and BL between 2017-2018 ranged from 10-25‰.

The decrease can be explained by the increase in rainfall. According to the Florida Department of Agriculture, mean rainfall for our area is 60.4”. In 2017, our area received 90.0”.

 

Total Suspended Solids

Most samples were < than 10mg/L. Beginning in June there was a slight increase in some samples to 20-45 mg/L but most were still less than 10mg/L.

Again, the increase is total solids could be connected to the increase in rainfall and run-off.

 

Nutrients

Nutrient concentrations were relatively low. BL had higher concentrations of chlorophyll a than SRS – suggesting higher levels of nutrients. A possible cause could be higher levels of run-off in BL, or, more nutrients within the run-off BL is receiving.

 

 

DISCUSSION

 

This project is just beginning and will need more time to determine how the seagrasses within these systems are changing over time. Between BL and SRS, 17 stations were monitored. The percent seagrass coverage within those stations ranged from 48-100% coverage (mean of 66%). The difference in percent seagrass coverage between BL and SRS was not significant. However, there was a significant difference in percent coverage of drift algae – BL had more. BL also had higher levels of chlorophyll a (a measure of plankton production and possible link to higher levels of nutrients).

Increase rainfall has occurred in recent years; there was a 49% increase between 2017 and our measured norm. Increased stormwater run-off can be problematic for recovering seagrasses. Though total suspended solids remained below 10mg/L for most samples, there was an increase during the summer months. The increase in drift algae and chlorophyll a in BL suggest that either (a) there are more stormwater run-off access points or (b) there is more nutrients within the water running off; more time and samples are needed to determine whether this trend holds.

Remember also, that the SRS samples all came from the eastern end of that body of water and may not reflect the entire Sound.

 

If you are a local resident and would like to learn more on how you can either (a) reduce run-off from your property, and/or (b) reduce the amount of nutrients in the run-off from your property, contact your county Florida Sea Grant Agent at the local county extension office.

Escambia – Rick O’Connor – (850) 475-5230 ext 111; roc1@ufl.edu

Santa Rosa – Chris Verlinde – (850) 623-3868; chrismv@ufl.edu

 

You can also contact us for a copy of the full 2018 seagrass report.

 

This long term project will continue and we will continue to update reports annually.

We would like to sincerely thank those volunteers who sampled and monitored for us in 2018.