Some grasses actually live underwater. In shallow estuaries (places where salt and freshwater mix) in California, eelgrass roots in the mud and grow upward to the surface of the water. Eelgrass grows best where it can stay submerged all the time, where not even the lowest tides expose it to the air. Channels, deeper areas where water flows in and out with the tide, are the best places for eelgrass to grow.
In eelgrass beds, beds under the sea that rock back and forth with the waves, young fish find hiding places where they can safely grow.
Most importantly, eelgrass is the number one food of Brant geese. The geese live in far areas of the Arctic circle in the summer, but they fly to the Pacific coast of the United States in winter. They settle in bays where they can find eelgrass, which comprises 95% of their winter diet. When I looked for Brant geese in Morro Bay , California, I found them clustered in certain deeper areas. Later when I looked at a map that shows where eelgrass grows best, I recognized that the Brant geese were floating over those same eelgrass areas. When I saw the geese, I was surprised to realize that they were not much bigger than mallards. So not all geese are bigger than ducks.
When eelgrass is tossed up onto the shore, as in the photo above, it provides food for many mudflat animals such as snails and barnacles.
Eelgrass is an important symbol of how healthy an estuary is. The grass grows best when the water is clear, when there are nutrients in the water, when the temperature is right, and when there is not too much mud in the water.
In the Morro Bay estuary in central California, many eelgrass plants died after wildfires inland in 1994-95. When large winter storms washed the ash and dirt from the fires into the bay, the water became too cloudy for eelgrass to grow.
Since that time, the eelgrass has slowly returned. From 2007 to 2008, acreage of eelgrass increased by 56 acres. Since it is difficult to see where all the eelgrass grows underwater, scientists used planes to fly over the bay to try to map it. Then they checked by "ground-truthing," paddling in kayaks to look underwater to find the grass.
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