Seagrass Monitoring; Eyes on Seagrass 2023 Report

Most know and understand the importance of seagrasses to the ecology of an estuary.  It is believed that at least 80% of the commercially, and recreationally, important finfish and shellfish species spend at least part of their lives in the seagrass.  These habitats provide food and shelter for the developing young and are critical for such species as seahorses and scallops.

Seagrass bed acreage has declined over the last half century.
Photo: Rick O’Connor

A 2016 U.S. EPA publication stated that at one time the Pensacola Bay area had about 6000 acres of seagrass.  We currently have around 4000.  The loss began in the 1950s and was not of concern right away but as people began to understand the importance of this habitat there have been discussions and publications on how to restore it.


Most efforts to plant new seagrass across the state have been unsuccessful.  Another approach is to remove the stressors that caused the decline.  These stressors include lower water clarity, seagrasses need at least 25% of the ambient light at the surface to reach the bottom for photosynthesis.  Many species need the salinity of the water to be at, or above, 20 parts per thousand (ppt).  Increase development and stormwater runoff could decrease salinity.  Seagrasses are sensitive to high wave energy.  Seawalls and boats have increased wave energy within these systems and boats also cut prop scars with the grass beds that take years to heal.


In some parts of the state, where these stressors have been addressed, seagrass has naturally restored itself.  There has been effort in the Pensacola Bay System (PBS) to reduce some of the stressors not only for the seagrasses, but other issues of concern.  Since 1974 periodic estimates of seagrass acreage have been conducted.  The Pensacola-Perdido Bay Estuary Program is currently conducting such an assessment.  About a decade ago Dr. Jane Caffrey (University of West Florida), along with her students and biologists from the Florida Fish and Wildlife Conservation Commission (FWC) began monitoring seagrasses in the PBS.  When funding for this project ended in 2017, Dr. Caffrey asked Florida Sea Grant if a citizen science project could be developed to continue the monitoring.  This project would eventually be called Eyes on Seagrass.


Volunteers in this program monitor selected sites across the PBS.  Monitoring includes percent coverage of seagrass and drift algae, species composition and abundance, and water samples are collected to monitor total suspended solids and nutrients concentrations.  UWF students also monitor temperature, salinity, dissolved oxygen, light, and pH at some of these locations.  Monitoring is occurring in Big Lagoon, Bayou Grande, Bayou Texar, Project Greenshores, and Santa Rosa Sound.  Volunteers monitor their locations once a month between April and September.


In 2023 Sea Grant trained 21 residents, 13 of which actually participated in monitoring.  Here are their results:


Big Lagoon

Monitoring occurred at Big Lagoon State Park and near Ft. McRee.  The abundance of grass was higher near the state park and the abundance of grass at this site was similar to the results in 2022.  The site near Ft. McRee not only was less than the sites near the state park but had declined since 2022.  Most of the grass found was shoal grass (Halodule wrightii) a thin blade species that typically grows closer to shore.


Santa Rosa Sound

The site at Shoreline Park near Gulf Breeze was almost 100% covered each month.  It included not only shoal grass but the wider blade turtle grass (Thalassia testudinum) which is more sensitive to waves and typically grows in deeper water.  It is the grass that bay scallops require for their life cycle.  Not only was the coverage of seagrass here almost 100% throughout the season, but there was also a 30% increase in coverage from 2022.


The Naval Live Oaks site is a mile or two east of Shoreline Park.  The grass here was not as abundant as Shoreline Park but was the second most abundant site in the Sound.  The coverage was about the same as it was in 2022.


Park West is due south of Shoreline Park on Pensacola Beach.  Coverage here was less than 40% and saw a 10% decline from 2022.


The sites monitored near Big Sabine had the lowest values with most having less than 40% seagrass within their quadrats.


Pensacola Area

The sites within Bayou Grande ranged from 22-50% coverage.  Most of the grass was widgeon grass (Ruppia maritima), a species that can handle lower salinities, but shoal grass was present.  These monitoring sites showed a 95% decrease in coverage from the data collected in 2022.


The site in upper Bayou Texar ranged from 20-100% coverage but was consistently at 100% in 2022.  NOTE: this volunteer reported 0% (no seagrass) at this location with his first visit to the site this year.  He will continue to monitor to determine whether it returns.  The seagrass monitored at this location is tape grass (Vallisneria americana), a species that prefers very low salinity.


The Project Greenshores site includes both widgeon and shoal grass.  The monitoring site was less than 5% seagrass in 2023, this is a 50% decline since 2022.


Drift Algae

Though many species of animals will utilize mats of drift algae growing on seagrasses, it can reduce light and cause seagrass to decline.  In 2023 mats of drift algae were more abundant in Big Lagoon and more consistent at the state park.  The sites at Santa Rosa Sound reported near 0% drift algae, but in 2022 these sites reported 50% coverage.


Points of Interest

As mentioned above, the volunteer who monitors Bayou Texar has surveyed his location already this year and found no seagrass present.  The volunteer who monitors the site near Ft. McRee has also reported this year that this site has very little seagrass.  Both will continue to monitor these locations to determine whether the grass returns during the summer growing months.


Another point to be made here is that the locations are relatively small and do not speak for the waterbody as a whole.  Each volunteer has a 20 meter transect line in which, using a 0.25m2 quadrat, they measure the abundance of seagrass every 5 meters along the line.  They do measure the same site each year, but they do not cover large areas.


If you have questions about this project, contact Rick O’Connor at the Escambia County Extensions Office.  (850-475-5230 ext. 1111) or


Posted: June 6, 2024

Category: Coasts & Marine, Natural Resources
Tags: Eyes On Seagrass, Florida Sea Grant, Seagrass

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