Sea Grasses
Sea grass (also known as submerged aquatic vegetation or SAV) is a name for plants growing under the surface in shallow coastal waters. Although submerged, these plants are similar to terrestrial plants in that they also have leaves, stems, roots, and flowers. Sea grass is critical to many fish, shellfish, invertebrates and waterfowl living in the ocean and coastal areas. It can provide food and habitat for aquatic animals; produce oxygen from photosynthesis; slow down wave action and reduce erosion; and remove excess nutrients from water.
While SAV can help to improve water quality, it also responds to changes in water quality. Because SAV plays many key roles in maintaining the ecological health of an area as well as responds to localized water quality conditions, its presence, abundance, diversity, and health can indicate the health of an estuary or local coastal waters. Unfortunately, the abundance of SAV is declining.
The most significant threat to SAV is the loss of light. Just like terrestrial plants, SAV need light to survive. Floating particles of sand, dirt, and decaying matter can block light from reaching the SAV. Excessive amounts of these floating particles can be caused by shoreline erosion due to construction, agriculture, or natural processes.
While SAV require nutrients such as nitrogen and phosphorus to survive, too much of a good thing can cause problems! Excess nutrients from fertilizers and/or agricultural waste, outflow from sewage treatment facilities, and direct runoff from the land stimulate excess algae production, blocking light from the SAV.
Development can also affect SAV. Shading caused by docks and piers will kill existing seagrass. Bridges, canals and ship traffic can also cause changes in water movement that may affect the ability for SAV to survive. Dredging may dig up SAV, and the resulting changes in water depth both in the areas dug and where dredged materials are deposited may not be suitable for seagrass.
Seagrass beds are also often damaged by jet skis and motorboats when the propellers cut through the root system, causing significant damage. While seagrass can recover quickly from damage from storms, unusual cold, or overgrazing by marine organisms, damage to the root systems causes scars that are visible for years in the seagrass beds.
Coastal communities are pulling together to maintain healthy estuaries through such activities as lifestyle changes, citizen water quality monitoring projects, and participating in efforts to replant seagrass beds.