Eelgrass -- November, 2015 - John Longstreth Nature Photography

Eelgrass?  Many of us have the perception that it's spreading like crazy, getting closer to the docks, fouling props, tangling up with swimmers, just being a nuisance. Yet marine biologists and ecologists write passionately about how critically important it is. So I figured we should know a little more about this little appreciated but major feature of our Tomales Bay.

Eelgrass is a flowering plant in the genus Zostera. Yes, it is a flowering plant, not seaweed or algae. It flowers, is pollinated and germinates seed all under salt water. Zostera is one of the most widely distributed genera in the world. Our particular species, Z. marina grows on both North American coasts and has leaves 1/4-1/2" wide and up to 3 feet long. It is a perennial with thick rhizomous roots. New leaves sprout in spring and are thickest in early summer, dying back in autumn and winter. It does not like fresh water, so its spreading in our bay might be the result of less creek water flowing into the bay due to the drought and the upstream dams .

So why is it important to our environment? Ecologists know that it fills many functions. Herring are dependent on eelgrass as they lay their eggs on it. Salmon smolts and other small fish use it for their nursery and shelter. This time of year, kayakers see leopard sharks and rays hunting in eelgrass patches. Black Brant, a lovely small goose, graze on it, using it as their major winter food. Other waterfowl also feed in the eelgrass patches, either on the grass itself or on the myriad small crustaceans and other little critters that live there. When a fungal blight hit the eelgrass on the east coast, the decimation of this habitat was held partially responsible for the collapse of coastal fisheries.

So the next time you are swimming or sailing and get tangled up in eelgrass, you will, hopefully, have a little more understanding and maybe even appreciation for it.

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