Sequoia Scientific

Eelgrass, Sediment, Healthy Oceans, & the LISST-Tau

October 7, 2021

What is Eelgrass?

Eelgrass is a type of flowering marine plant that grows in large patches, or beds ( While they may at a glance seem similar, seagrasses are very different from seaweeds, which are a type of algae. When seagrass grows across large areas, the habitat it creates is called a seagrass meadow. Typically found in bays and estuaries, eelgrass grows in a sheltered, shallow environment ( Eelgrass meadows play an important role in keeping our oceans healthy by: creating shelter to young fish and invertebrates, providing food for more than 1,000 species of fish, improving water quality and trapping sediment ( Eelgrass even absorbs large amounts of greenhouse gasses, playing an important role in combating climate change (

Eelgrass at Risk

There has been significant harm done to eelgrass meadows because of human activities such as urban development, dredging, pollution, and sediment runoff ( Seagrass meadows around the world are being lost at a rate of around 7% each year, or an area equal to two football fields every hour (Waycott et al).

Recently, more research is being done to determine what degrades eelgrass beds, and how they can be restored. In 1966, the US federal government designated eelgrass as Essential Fish Habitat and a Habitat of Particular Concern. Recent studies on eelgrass habitats include studying the role it plays in sediment resuspension, the effect that increased sediment has on eelgrass health, and even the impact that grazing and fecal addition by geese have on eelgrass flowering.

Eeelgrass & Sediment

On the one hand, eelgrass traps and reduces the amount of sediment suspended within the water of its ecosystem. Trapping sediment reduces the force of wave energy and coastal erosion ( But when too much sediment is introduced to the ecosystem, the sediment can block light and reduce the health of the eelgrass living there (Adams et al). As the eelgrass bed loses vitality and grows smaller, the sediment that it was trapping is released, thus creating an even more inhospitable environment for the eelgrass (Adams et al). It is becoming increasingly important to monitor the environments where eelgrass live and regulate human activity that contributes to the loss of these meadows. Additionally, as restoration projects are being funded to replant eelgrass meadows, it is important to collect information on how to ensure the greatest success while doings so.

Eeelgrass & the LISST-Tau

Released this year by Sequoia Scientific, Inc. the LISST-Tau is an instrument highly suited for measuring the optical transmission, a proxy for suspended sediment in eelgrass environments and has already been used in such applications. The compact, 2,000-m rated high-precision transmissometer is available with a green or red light source and uses a 15-cm pathlength for high-precision measurements across a wide range of water types. Interested in how this instrument can work for you? Check out this short video.

Where Can I Find Out More?

Project Seagrass: International seagrass conservation charity:

SeagrassWatch: International seagrass monitoring network:

World Seagrass Association: International association of scientists and conservationists interested in seagrass conservation and biology: