From May 27–30, 2025, St. Johns RIVERKEEPER (SJRK) conducted the first field visit of Year 3 of the SAVe Our River’s Grasses Expedition, continuing efforts to investigate the alarming decline of submerged aquatic vegetation (SAV) in the St. Johns River. The team surveyed an 80-mile section of the river between Doctors Lake and Lake George, documenting remaining grass bed locations, collecting water quality data, and identifying potential restoration strategies for this critical habitat.
Temporary Enclosure Initiative
To further advance the understanding of SAV dynamics and test practical recovery methods, SJRK launched the Submerged Aquatic Vegetation (SAV) Protective Enclosure Project during the week of April 28, 2025. This effort represents a significant expansion of the SAVe Our River’s Grasses Expedition and involves the installation of small-scale SAV exclusion enclosures at ten designated sites along the 80-mile stretch. These protective structures are designed to shield SAV from grazing pressure and other environmental stressors, allowing researchers to monitor regrowth potential under controlled conditions. SJRK partnered with the Coastal Conservation Association (CCA) and Mighty River Recovery (MRR) to make this effort possible.
As of the May 2025 expedition, nine of the ten enclosures had been successfully installed. The installation at the Doctors Lake site was postponed due to the presence of a harmful algal bloom (HAB) and is scheduled to be completed later in the summer when conditions improve.
The primary objective of the Submerged Aquatic Vegetation (SAV) Protective Enclosure Project is to temporarily reduce herbivory pressure on native submerged grasses and their associated seed banks and rhizome networks. By excluding grazers, the project aims to support the natural recovery processes of existing SAV, allowing for uninterrupted growth, germination, and propagation. These protective enclosures are intended to generate site-specific data to inform future restoration strategies and assess the potential for natural SAV expansion under reduced grazing conditions.
It is important to note that this project does not involve the active planting of SAV. For additional details, please refer to the Submerged Aquatic Vegetation (SAV) Temporary Protective Enclosures FAQ page
May 2025 Expedition Findings
While SJRK is encouraged by the detection of SAV at 13 of the 14 monitoring sites, the overall condition of the grasses remains a concern. At many locations, SAV continues to exhibit limited height, stunted growth, and sparse bed coverage, indicating ongoing stress or suppression.
The following is a site-by-site summary, presented in the order the locations were surveyed:
Doctors Lake
Unfortunately, conditions at the Doctors Lake site indicate a regression in SAV health compared to the previous year. In May 2025, average canopy height was reduced by approximately 50% relative to May 2024, and SAV coverage declined sharply to just 0.7%, down from 33% the year prior. However, this still reflects an improvement over May 2023, when no submerged aquatic vegetation was observed at the site. The installation of the protective enclosure—currently scheduled for the coming months—is expected to help alleviate grazing pressure and may support future recovery of SAV in this area.
Water quality at this site remained consistent with conditions observed during previous field visits conducted at this time of year. Notably, salinity levels during the month of May have consistently remained elevated compared to other times of the year, averaging 5.58 ppt across the May 2023, 2024, and 2025 sampling events. In contrast, the average salinity during all other sampling months was significantly lower at 0.73 ppt.
Fruit Cove
The protective enclosure at the Fruit Cove site was installed on May 1, 2025. The Fruit Cove site yielded encouraging results in terms of species diversity and SAV canopy stability. Historically, only Vallisneria americana (eelgrass) has been observed at this location. However, in 2025, Ruppia maritima (widgeongrass) was also identified, indicating a potential increase in species diversity and habitat complexity.
Canopy height outside the protective enclosure remained relatively stable year-over-year, averaging 3.33 cm in May 2025 compared to 3.6 cm in May 2024. However, average percent cover declined significantly, from 46% in 2024 to just 12% in 2025. In contrast, SAV conditions within the protective enclosure were more consistent with last year’s baseline: percent cover averaged 39%, and canopy height increased to an average of 4.9 cm. These preliminary findings suggest that the protective enclosure may be contributing to improved SAV growth conditions at this site.
Water quality at this site remained consistent with conditions observed during previous field visits conducted at this time of year. Similar to conditions observed at Doctors Lake, salinity levels at this site during the month of May have consistently remained elevated, averaging 6.08 ppt across the May 2023, 2024, and 2025 sampling events. In contrast, the average salinity during all other sampling months was significantly lower, at 0.31 ppt.
Orangedale
The Orangedale site exhibited a notable decline in SAV condition compared to the previous year. In May 2024, Vallisneria americana (eelgrass) reached an average canopy height of 6.3 cm, with percent cover at 55%. By May 2025, average canopy height had decreased to 2.8 cm, and SAV cover had declined to 17%.
The protective enclosure at the Orangedale site was installed three weeks and five days prior to St. Johns Riverkeeper’s May 2025 survey. Within the protective enclosure, the decline was less pronounced. Canopy height averaged 3.4 cm and percent cover was 16%, suggesting some degree of protection or resilience within the enclosed area.
Species diversity also declined year-over-year. In 2024, four species were documented: Vallisneria americana, Najas guadalupensis (guppy grass), Chara spp. (musk grass), and Eleocharis spp. (spikerush). In 2025, only Chara spp. and Vallisneria americana were observed, indicating a potential reduction in ecological complexity and habitat quality at this site. Water quality at this site remained consistent with conditions observed during previous field visits conducted at this time of year.
Colee Cove
St. Johns Riverkeeper had planned to conduct comparative SAV assessments both inside and outside the protective enclosure at the Colee Cove site, installed 3 weeks and 4 days prior. However, due to the presence of a widespread harmful algal bloom (HAB), field access was restricted, and the team was unable to safely enter the river or perform SAV surveys at this location. As a result, no data were collected for Colee Cove during the May 2025 expedition.
An elevated water temperature was recorded at this site, approaching 90°F. Such elevated temperatures may have contributed to the presence of the algal bloom observed during the field visit, as higher water temperatures are known to promote algal growth and exacerbate bloom conditions.
Mays Cove
The Mays Cove site produced unexpected results during the May 2025 survey. Contrary to expectations, SAV density was higher outside the protective enclosure, with 67% coverage observed outside compared to 44% inside. The external coverage was consistent with data from May 2024, which showed a 72% SAV cover. The protective enclosure was built precisely four weeks and two days prior to the subsequent SAV survey conducted by St. Johns Riverkeeper.
Canopy height measurements revealed a slight advantage within the enclosure. Vallisneria americana averaged 3.3 cm in height inside the enclosure, compared to 2.4 cm outside. These values are slightly lower than the 2024 average of 4.41 cm but still fall within a comparable range.
Species richness was notably higher outside the enclosure. External observations included Vallisneria americana, Sagittaria subulata, Eleocharis spp., Ruppia maritima, and Chara spp., while only Vallisneria americana and Chara spp. were documented within the enclosure. These findings suggest that localized factors—such as microhabitat conditions, grazer behavior, or hydrology—may be influencing the effectiveness of the protective structure at this site.
Despite a slightly elevated chlorophyll-a reading of 9.33(µg/L), water quality at this site remained consistent with conditions observed during previous field visits conducted at this time of year.
Dancy Point
During the past two May expeditions, SJRK consistently surveyed within the Florida Fish and Wildlife Conservation Commission’s (FWC) three-acre protective enclosure at Dancy Point in East Palatka. In previous years, this site reliably exhibited long, healthy stands of SAV, particularly Vallisneria americana (eelgrass), within the enclosure.
However, in early September 2024, the enclosure was compromised, allowing grazers unrestricted access. Within approximately three weeks, the eelgrass—previously reaching historic lengths and densities—was reduced to short, heavily grazed stubble, demonstrating the enclosure’s critical role in SAV protection.
In May 2025, post-breach conditions reflected this impact. Average canopy height for eelgrass was reduced to 3.6 cm, and Chara spp. averaged 5.53 cm, with overall SAV bed coverage at 25%. These values closely mirror those recorded outside the enclosure in May 2024, when Vallisneria americana averaged 3.44 cm, Chara spp. reached 6.5 cm, and total SAV coverage was approximately 21%. These observations highlight the vulnerability of SAV to herbivory and underscore the effectiveness of protective enclosures in facilitating sustained growth.
Despite an elevated chlorophyll-a concentration of 10.64 µg/L, water quality at this site remained consistent with conditions documented during previous field visits conducted during the same seasonal period.
Forrester Point
Forrester Point is a newly established monitoring site, added in 2024. Due to unfavorable conditions—including elevated water levels and the presence of algal blooms—SAV surveys could not be conducted during its initial year.
In May 2025, the site yielded surprising results. The protective enclosure for this site was installed on April 28. Within the protective enclosure, the average SAV canopy height was 3.66 cm with only 4% coverage. In contrast, outside the enclosure, the average canopy height was slightly lower at 3.14 cm, but SAV bed coverage was substantially higher at 21%. These unexpected patterns suggest that enclosure effects may vary site-to-site and may be influenced by local hydrology, nutrient availability, or grazer behavior. Continued monitoring will be necessary to assess trends and potential ecological drivers at this location.
Water quality parameters remained consistent with those observed last year; however, water temperatures were more moderate compared to May 2024, when they approached 90°F. Additionally, the chlorophyll-a concentration was approximately half of what was recorded during the same period last year, indicating potential reasoning for improved water clarity and reduced algal activity.
San Mateo
The San Mateo site features a protective enclosure constructed in March 2022. Since the initiation of the SAVe Our River’s Grasses Expedition in 2023, SJRK has conducted annual SAV surveys within the enclosure to monitor long-term recovery trends.
In May 2025, average canopy height reached 11.67 cm, only slightly below the 12.9 cm recorded in May 2024. This represents substantial progress compared to May 2023, when the average height was just 2.27 cm, indicating a strong upward trend in vegetative growth over the past two years.
However, SAV percent cover declined in 2025 to 35%, down from 78% in 2024 and 51% in 2023. This reduction in coverage, despite consistent canopy height gains, suggests that factors such as seasonal variation, nutrient availability, or internal competition within the enclosure may be influencing bed density. Continued monitoring will help determine whether this reflects a temporary fluctuation or a longer-term trend. Water quality parameters were similar to those recorded last year. However, water temperatures were milder than in May 2024, when they neared 90°F. Furthermore, chlorophyll-a levels were about half of what was measured during the same time frame last year.
Floridian Club
The Floridian Sports Club site in Welaka was added to the SAVe Our River’s Grasses Expedition in 2024. Located at the historic Floridian Sports Club Fish Camp—acquired over 40 years ago by Johnny Morris, owner of Bass Pro Shops—this site holds cultural and ecological significance within the bass fishing community, making it a strategic location for monitoring SAV conditions.
In May 2024, both Vallisneria americana (eelgrass) and Chara spp. were documented at this site, with an average SAV coverage of 16%. However, by May 2025, only Chara spp. was observed, and total SAV coverage had declined to 3.5%. Despite this reduction in coverage, average canopy height for Chara remained stable at 5 cm across both years. These results suggest a potential decline in SAV species diversity and overall bed density, warranting continued monitoring to determine whether this reflects a site-specific stressor or broader regional trends. Water quality parameters were similar to those recorded last year except for a higher water temperature by about 4 degrees reaching almost 86°F.
Beecher Point
SJRK returned to Beecher Point, one of the original sites established at the start of the SAVe Our River’s Grasses Expedition in May 2023. Unfortunately, no SAV was observed at this site during the May 2025 survey. Similarly, the most recent prior visit in October 2024 yielded no detectable SAV presence. Water quality parameters were generally similar to those recorded last year, with the exception of a higher water temperature nearing 90°F, a decrease in dissolved oxygen saturation from 151% last year to 92.5% this year, and a lower chlorophyll-a concentration of 2.8 µg/L.
Historically, Chara spp. had been the dominant species at Beecher Point, with Vallisneria americana (eelgrass) also recorded during the May 2024 survey. The absence of both species in recent visits suggests a possible site-level decline in habitat quality or persistent environmental stressors inhibiting SAV growth. Continued monitoring and additional investigation into potential limiting factors will be necessary to determine the cause of this sustained decline.
Jenerson Point
Jenerson Point was selected as a site for the installation of a protective enclosure on April 28, 2025. SJRK previously monitored this location in 2024. Although Vallisneria americana (eelgrass) had been documented at Jenerson Point in past surveys, only Chara spp. was observed during the May 2025 visit.
SAV coverage outside the enclosure was 11.56% in 2025, a slight decrease from 16% recorded in May 2024. However, inside the enclosure, coverage was substantially higher at 52%. Similarly, Chara canopy height averaged 11.7 cm inside the enclosure, compared to 6.9 cm outside, and showed considerable growth relative to May 2024 when the average canopy height was only 2.9 cm. These results suggest the protective enclosure may be effectively promoting SAV recovery and growth at this site.
Water quality parameters were generally similar to those recorded last year, with the exception of a higher water temperature nearing 90°F, a decrease in dissolved oxygen saturation from 178.40% last year to 100.65% this year, and a lower chlorophyll-a concentration of 2.73 µg/L.
Drayton Island
The Drayton Island site has been included in monitoring efforts since May 2023; however, SJRK has been unable to complete SAV transects at this location due to a combination of factors, including elevated water levels and harmful algal blooms. During the May 2025 field visit, conditions were sufficiently favorable to conduct a full survey.
At this time, only Chara spp. was observed. Within the protective enclosure—installed on May 15, 2025—the average canopy height reached 14.3 cm with SAV coverage of 67%. Outside the enclosure, canopy height was substantially lower at 8.8 cm, with a markedly reduced coverage of 19%. These results highlight the potential benefits of the enclosure in promoting SAV growth and density.
Water quality parameters were generally similar to those recorded last year, with the exception of very high water temperatures nearing 92°F.
Due to the alarming green color of the substrate at this site, sediment samples were taken to the lab, indicating a potentially harmful type of cyanobacteria called Oscillatoria was found in moderate amounts (more than 10 filaments per milliliter of water). Other cyanobacteria growing on plants or surfaces were also observed, but it’s unclear if those are harmful. In addition, there were high levels of other algae, including diatoms, green algae, desmids, and non-toxic cyanobacteria such as Planktolyngbya (both straight and coiled forms) and Pseudanabaena.
Georgetown North
The Georgetown North site had a protective enclosure installed on April 29, 2025. Due to the presence of a harmful algal bloom (HAB) outside the enclosure, survey efforts during the May 2025 expedition were limited to within the enclosure.
During the May 2024 survey, both Vallisneria americana (eelgrass) and Chara spp. were present, with eelgrass canopy height averaging 3.3 cm and combined SAV coverage at 43%. In contrast, inside the enclosure in May 2025, eelgrass canopy height increased to an average of 7 cm, and combined percent cover for eelgrass and Chara spp. reached 46%. These findings suggest positive early growth responses within the enclosure.
Water quality parameters were generally similar to those recorded last year, with the exception of a decrease in dissolved oxygen saturation from 134.9% last year to 95.3% this year, and a lower chlorophyll-a concentration of 2.92µg/L versus 9.44µg/L last year.
Lab reports show a potentially harmful type of cyanobacteria called Microcystis was found in high numbers (more than 30 colonies per milliliter of water). Many other types of algae were also present, including diatoms, green algae, desmids, and several types of non-toxic cyanobacteria such as Planktolyngbya (straight and coiled forms), Pseudanabaena, and Aphanothece.
Sediment samples show a potentially harmful type of cyanobacteria called Phormidium was detected, though only in small amounts (1 filament per milliliter of water). Other cyanobacteria growing on surfaces or plants were also seen, but it’s unclear if they are harmful. High levels of other algae were present, including diatoms, green algae, desmids, and non-toxic cyanobacteria like Planktolyngbya (straight and coiled forms) and Pseudanabaena.
Georgetown South
The Georgetown South site also had a protective enclosure installed on April 29, 2025. Similar to Georgetown North, the presence of a harmful algal bloom (HAB) and concerns regarding local wildlife limited sampling efforts to within the enclosure. Due to previous challenges such as elevated water levels and algal blooms during past expeditions, this survey represents the first successful SAV assessment at this site.
During the May 2025 survey, Chara spp. and Ruppia maritima (widgeongrass) were identified. The average canopy height for Chara was 12.14 cm, notably higher than measurements recorded at other sites, while Ruppia exhibited an average canopy height of 28 cm. Percent cover within the enclosure was measured at 75%, indicating a robust SAV presence despite environmental constraints. St. Johns Riverkeeper looks forward to the upcoming field visit in July to conduct comparative analyses of the current data.
Water quality parameters remained consistent to those recorded last year, with the exception of a decrease in dissolved oxygen saturation from 154.7% last year to 92.90% this year, and a lower chlorophyll-a concentration of 3.08µg/L versus 8.48µg/L last year.
Lab reports of the algal boom show a type of potentially harmful algae called Microcystis was found in high amounts (more than 50 colonies per milliliter of water). Large numbers of other algae were also present, including diatoms, green algae, desmids, and several types of cyanobacteria such as Planktolyngbya (both straight and coiled forms), Pseudanabaena, and Aphanothece.
Sediment samples show a large number (over 8,000) of filaments from a potentially harmful type of cyanobacteria called Oscillatoria were found. Other cyanobacteria, growing on plants or surfaces in the water, were also seen, but it’s not clear if these are harmful or not. High amounts of various other algae were also present, including diatoms, green algae, desmids, and non-toxic cyanobacteria like Planktolyngbya (both straight and coiled forms) and Pseudanabaena.
Thank You to Our Partners
St. Johns Riverkeeper extends sincere gratitude to all those who have made this effort possible. This initiative would not be feasible without the generous support of riverfront residents and their neighbors, advising scientists, community leaders, anglers, and all individuals dedicated to the stewardship of the river. Their collaboration and commitment have been instrumental in the success of the SAVe Our River’s Grasses project and our ongoing partnership. Together, we are making a meaningful difference in restoring and protecting this vital ecosystem.