The coral reef ecosystem extends far beyond the stony skeletal structures set up by the coral polyps. It includes waving meadows of seagrasses, spidery networks of mangrove roots, and even the clear blue ocean currents that wash along the reef's edge. All of these components are crucial for the colorful array of life we see at the reef. Much of that life begins in the seagrass beds.

These marine flowering plants differ from algae in that they have true roots, stems, and leaves. Seagrasses produce seeds, although their flowers are often inconspicuous. In addition, Seagrasses form horizontal stems called rhizomes. Scientists believe these aquatic plants are derived from terrestrial plants which returned to the sea by gradual, progressive steps of acclimation to shallow fresh water, to shallow brackish water, and finally to submersion in marine water. The adaptation to a submerged life in marine waters involves a complex set of anatomical, morphological and physiological changes. Special adaptation to life underwater include large air canals in the grass blades. The rhizomes, too contain continuous air canals, as well as storing necessary starch for the plants. Seagrass roots are designed for extracting nutrients from the sediments in which they are anchored, but they too have air canal structures.

Seagrasses are a major reason our waters are so famous; they help to keep them free of sediment so that coral can have the clear water it needs to survive. They entrap particles in the water, binding them into sediment under their complex root systems.

Seagrasses are a principal contributor to the marine food web that ultimately provides humans with their seafood. They provide vital shelter for larval and juvenile fish, allowing them the chance to grow into adults. They serve as home to a diversity of crustaceans and other critters that provide a banquet for adult reef fish populations.

Finally, seagrasses can aid in improving water quality problems by incorporating some pollutants into plant biomass, or binding it into the sediment they stabilize.

Simply put, the coral reef needs the seagrass beds to survive.

Although it may seem plentiful, seagrass faces many of the threats that does our coral reef. Prop dredging and scarring has affected about 30,000 acres of seagrass in the Keys. Groundings take a toll on them as well.

Seagrasses don't grow like your lawn. When their root systems and vital rhizomes are torn by boat propellers, they can take as long as seven years to grow back -- if they can. In many cases, the damaged area allows more water to flow through and a new channel is begun, one with water flowing too quickly to allow the grasses to ever recover. And so the topography of an entire reef flat can be changed forever by one careless boater.

The more we learn about our planet, the more we understand the interconnectedness of the life that inhabits it. We can no longer protect one piece because we think its valuable and ignore another because we feel it has no direct use. We need the coral reef; the coral reef needs the seagrasses.

Next time you want to go out snorkeling, forego the reef and take a close-up look at a nearshore seagrass bed. Take a look at where it all begins!

- Alyson Matley
Florida Keys National Marine Sanctuary
The Sounding Line