SAV Field Highlights: September 2026
From September 1–4, St. Johns Riverkeeper conducted the final SAVe Our River’s Grasses Expedition survey of 2026, wrapping up year four of this five-year initiative.
After the widespread harmful algal blooms (HABs) we encountered during our July survey, we were interested to see what conditions would look like in September. Algal blooms, including potentially toxigenic cyanobacteria (“blue-green algae”), were still widespread. However, conditions had improved considerably since July, and the blooms were generally less severe.
During the four-day field visit, our team conducted:
- SAV surveys at accessible sites that were not significantly affected by algae
- water quality sampling
- visual assessments of algal blooms
- Screening for potentially toxigenic (PTOX) cyanobacteria at 13 of our 14 monitoring sites
Field Highlights:
Enclosures at several locations showed promising SAV growth. At several sites, eelgrass inside protective enclosures was taller and more abundant than the surrounding areas. We observed particularly strong recovery at Mays Cove, Forrester Point, San Mateo, and Georgetown North. At Drayton Island, we were especially encouraged to see eelgrass growing inside the enclosure, where it has not been observed in many years, a promising sign of recovery.
- The recovery we are seeing at some of the more southern sites has been slower and more delayed, but these observations demonstrate that eelgrass can return when conditions allow. The slower recovery at these sites, due to multiple stressors in the system, highlights the role the protective enclosures have played in giving eelgrass a chance to come back while protected from ongoing grazing pressure. Even when conditions are favorable for growth, young or sparse grass beds can be especially vulnerable to grazing. This initiative has provided concrete evidence of the enclosures’ ability to give eelgrass both the time and opportunity it needs to recover, expand, and become more resilient to external stressors.
- Not every enclosure showed the same results. Breaches in the protective enclosures at Doctors Lake and Fruit Cove were associated with reduced SAV density and shorter grass within the enclosures. Despite this setback, we are hopeful that the grassbeds have established a dense enough rhizome network under the substrate to bounce back before the next growing season.
- Algae continued to limit some surveys. At Orangedale and Colee Cove, traditional SAV surveys were impossible due to dense algae. However, visual observations indicated that the eelgrass remained robust and was reaching the surface of the water.
Potentially Toxigenic (“PTOX”) cyanobacteria were detected at 12 of the 13 sites screened. Several locations, including Forrester Point, Mays Cove, San Mateo, and Georgetown North and South, had relatively high abundances of PTOX cyanobacteria.
- The PTOX report also observed Microcystis at several locations, including Fruit Cove, Orangedale, and Colee Cove. Microcystis is a cyanobacterium known to include species capable of producing toxins such as microcystins.
- It is important to note that PTOX results are considered tentative at this stage. Microscopy can identify cyanobacteria that have the potential to produce toxins, but it cannot confirm whether toxins are actually being produced. Additional toxin analyses will determine whether toxins were present at these sites.
- While the September conditions were an improvement over what we encountered in July, the continued presence of algae and potentially toxigenic cyanobacteria demonstrates that harmful algal blooms and nutrient pollution remain a real concern for the St. Johns River.
St. Johns Riverkeeper will continue the SAVe Our River’s Grasses Expedition in the spring of 2027. We will also create a full report for our 2026 field visits for the public to view. See all of our past reports and learn more here.