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Seagrasses Need Healthy Water

Seagrasses have been called many things: underwater meadows, the nurseries of the sea, and canaries in the coal mine. All of those are apt descriptions for one of Florida’s most important habitats. 

Seagrasses are underwater plants that grow in sediment. In Florida, there are seven species of seagrass, and they generally grow in shallow coastal areas and estuaries (places where freshwater from rivers mix with saltwater from the sea). Some species of seagrass are more dominant than others. The depths at which they grow depend on how clear the water is since seagrasses require light for photosynthesis. In areas where water quality is poor or polluted, the range for seagrass decreases. With little to no light penetration, seagrass will die completely.

What does this mean for the ecosystem?

Numerous fish and crustaceans depend on seagrass for habitat, including juvenile fish, crabs, and even seahorses. Scallops nestle in thick seagrass meadows and along the edge of the beds, and stingrays and horseshoe crabs will take refuge in them as well.

But seagrasses are more than just beautiful areas teeming with wildlife. Many fish that are recreationally and commercially important, such as snook, sea trout, or red drum, will spend their earliest years in shallow seagrass-dominated waters. Here, the waves are calmer, food is abundant, and there are more places to hide. For this reason, seagrasses are often called the “nurseries of the sea.” Seagrasses are also the primary food source for the Florida manatee and green sea turtles.

Snook, a commercially and recreationally important species, will spend their earliest years in shallow seagrass-dominated waters.
At the coastal center in Matin County, seagrass fragments are collected, studied, and replanted in nurseries before transplanted back into the Indian River Lagoon. They continue to face the same water quality threats.

When water quality is bad, seagrasses tell us.

Since seagrass is so reliant on clean and clear water, they are considered indicator species. Essentially, if seagrass is able to grow, then water quality is generally good. And while some of the hardiest seagrass varieties, like turtle grass, can withstand several years of poor water quality, other varieties like shoal grass may be impacted after only a year or two of polluted water. 

What’s happening now?

Due to poor water quality and chronic harmful algal blooms in coastal estuaries like the Indian River Lagoon, tens of thousands of acres of seagrass have been lost in the last decade, impacting both marine biodiversity and human livelihoods. We absolutely cannot fix the seagrass problem without also addressing the water quality problem.

There are common-sense recommendations made by the Blue-Green Task Force that would result in cleaner water. Many of those recommendations have largely not yet been implemented by the Governor and Legislature.

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