Fishers Island Eelgrass

Discover how you benefit from submerged aquatic vegetation.

Seagrass Fact Cards

  • Seagrass is submerged aquatic plant classified as an angiosperm.

    This means that seagrass is a rooted, flowering plant that lives underwater. Seagrass grows in marine environments.

  • The most prevalent species of seagrass in Long Island Sound is eelgrass

    It is an important resource that is under threat from human impacts.

  • Globally, eelgrass is found in the temperate North Atlantic

    You can find eelgrass growing in lagoons, estuaries, and shallow coastal waters

  • Eelgrass requires plenty of light to survive and thrive. Eelgrass can only grow in deeper areas when the water is clear.

    Depth: 1.5 - 30ft

    Temperature: 15.3ºC ± 1.6ºC for growth, 23.3ºC ± 2.5ºC for photosynthesis

  • Eelgrass Sexual Reproduction

    It occurs in mid to late summer. Flowers are fertilized through drifting pollen; this process creates seeds that eventually disperse throughout the seabed. New seagrass plants come from these seeds.

  • Eelgrass Asexual Reproduction

    It occurs through the growth and elongation of the underground roots called rhizomes. New plants, called shoots, pop up along the rhizomes. This method of reproduction is a form of cloning and does not lead to genetic diversity in the species.

Eelgrass Works For You!

History of Eelgrass in Long Island Sound

Where has eelgrass been? What went wrong? Where is it now? How has it recovered in some places but not others?

What is Killing Eelgrass?

  • Sun and Clouds

    Climate Change

    Water temperature plays a critical role in water habitability by eelgrass. Temperatures exceeding 22°C cause the plant to be less productive and excessive exposure or heat indexes will kill it. The highest recorded water temperature on Fishers Island was nearly 23°C in 2021. The best idea scientists have to combat this threat is to transplant heat tolerant eelgrass from the Southeastern coast in Long Island Sound.

  • Chemical fertilizer

    Nitrogen Pollution

    On Fishers Island we have control over two main sources of nitrogen pollution: septic and fertilizer. Septic systems were not created to contain nitrogen leakage, so your septic may be fully functional but still contributing to nitrogen pollution. Only a specialized advanced nitrogen filtration septic system upgrade can prevent this damage. When fertilizer application is excessive or timed inappropriately the run-off will drain straight into our waters and fuel algal blooms and weaken the health of our eelgrass.

  • Boat anchor in eelgrass causing damage.

    Boating Damage

    Boating damage is caused by anchors, propellers, and running aground. Plants that are uprooted are killed. Fragmented habitats result in less biodiversity, which means fewer recreational fishing and snorkeling opportunities. Further, poor boating practices release sediments into the water column. When sediment enters the water column, previously trapped carbon and nitrogen pollutes the waters and cloudy waters block light from reaching the plants.

  • Cloudy water threatens eelgrass survival.

    Construction

    Construction in or near marine environments can shade eelgrass and disturb the sediment leading to cloudy waters. Eelgrass is a plant that requires a lot of light; decreasing the available light is detrimental to its health.