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Invasive Seagrass Found in Biscayne Bay: A Growing Concern for Florida’s Ecosystems

An invasive seagrass species has emerged as a potential ecological threat in Florida, marking a troubling expansion of its range from native regions of the Red Sea, Persian Gulf, and Indian Ocean. Researchers at Florida International University (FIU) have confirmed the presence of Halophila stipulacea in waters off Key Biscayne, an alarming development in the ongoing struggle against invasive marine species.

Marine scientist Justin Campbell announced the discovery, describing it as the first identification of this non-native seagrass in the continental United States. The findings, which are available on the preprint server bioRxiv, indicate that this seagrass could disrupt existing ecosystems by outcompeting native seagrasses, a concern raised by Campbell based on observations from other regions in the Caribbean.

Notably, a marina employee initially spotted the invasive seagrass and reached out to Campbell for further investigation. Halophila stipulacea began to spread significantly after the opening of the Suez Canal in the late 19th century, traveling on ships and their anchors before being reported in the Caribbean by the early 2000s.

Seagrass meadows are crucial to marine health, providing essential habitats for economically significant species such as fish, shrimp, and crustaceans. They also serve as a primary food source for various marine animals, including manatees and sea turtles. Moreover, these underwater grasslands play a vital role in carbon sequestration, helping to mitigate climate change by absorbing atmospheric carbon.

While further studies are underway to assess the impacts of this invasive seagrass, preliminary research suggests that some species of fish may be less inclined to use areas populated by shorter seagrasses for nursery habitats. Additionally, local sea turtles are reportedly avoiding the invasive species in favor of native varieties.

In contrast to the declining native seagrasses facing threats from climate change, Halophila stipulacea appears well-adapted to thrive in diverse environments, capable of growing rapidly in varying salinity, temperature, and light conditions. It can propagate through fragments that float and reestablish once they reach the seabed, exhibiting a remarkable resilience that allows it to flourish even at depths exceeding 60 feet.

“The introduction of another invasive species in Florida underscores our planet’s interconnectedness and the significant impact human activities can have on natural ecosystems,” remarked James Fourqurean, co-author of the study and director of FIU’s Coastlines and Oceans Division. Having dedicated over four decades to the study of seagrasses in Florida, Fourqurean is a leading voice in international efforts to promote the conservation of seagrass meadows, which are essential for carbon capture.

Fourqurean pointed out the necessity of taking urgent measures to limit the spread of Halophila stipulacea and to monitor its effects on local ecosystems. The distinct morphology of this species compared to native seagrasses raises questions about its ecological function and whether it provides comparable benefits to those native varieties.

Determining how long Halophila stipulacea has been present in South Florida remains uncertain, though Campbell suspects it may have been establishing for years, likely going unnoticed due to its resemblance to local flora. Crandon Marina, which can accommodate larger vessels capable of travel to established populations of this invasive species, served as a probable entry point to Biscayne Bay.

As researchers continue to explore the implications of this discovery, there is an urgent call for enhanced monitoring and surveys in large marinas throughout the region to better understand the spread of this invasive seagrass.

More information:
(Justin E. Campbell et al., “First record of the seagrass Halophila stipulacea (Forskkal) Ascherson in the waters of the continental United States (Key Biscayne, Florida),” bioRxiv, 2024.)
DOI: 10.1101/2024.09.02.610701

Source
phys.org