An Historic Look at Seagrasses, Indian River Lagoon

Area along Indian River Lagoon in Jensen 1945 where Ocean Breeze Park is today. (Historic aerial courtesy of Sandra Henderson Thurlow.)
Area along Indian River Lagoon in Jensen 1945 where Ocean Breeze Park is today. Note extensive seagrass beads.  (Historic aerial courtesy of Sandra Henderson Thurlow.)

Seagrass, the basis of life for the Indian River Lagoon… how much was there in the past and how does it compare with today?

This is not always an easy question to answer. I have asked the South Florida Water Management District for their records and basically their records show seagrass was declining in the 1970s and then there was more than ever in the 1990s, and then there was the crash in the northern and central lagoon in  2009-2013, but here in Martin County? They say the  seagrass comes and goes based on how heavy the releases from Lake Okeechobee and canals C-23, C-24 and C-25.

Mark Perry of Florida Oceanographic stated last year in 2013 that about 80% of the seagrass was lost in key areas. The SFWMD seems to always report it is coming back and improving but this is difficult for me to always believe because when Ed and I fly over it, it looks so disgusting if it is low tide and you can see it, full of algae and blackish in color.

Seagrass off Sewall's Point, June 2014, photo JTL.
Seagrass off Sewall’s Point, June 2014, photo JTL.

Anyway, today I thought I would share two of my mother’s historic photos for reference.

First, I must state that according  to Jensen and Eden on Florida’s  Indian River, by Sandra Thurlow, there were freshwater grasses in the lagoon even into the early 1900s. Her archives include an old ad from 1914 that reads: RIVER GRASS WILL NOT DISCOLOR THIS PAINT. Apparently before the St Lucie Inlet was opened by hand in 1892, the river was mostly fresh as at that time the natural inlet had closed. Over the centuries it opened and closed depending on the moods of Mother Nature.

When it was closed for any length of time, fresh water grasses filled the river; apparently there was a lot of iodine in the grass so if it were exposed in the hot summer months it would turn a “white house black.”

Old add to overcome freshwater seagrass staining. ( Thurlow archives.)
Old add to overcome freshwater seagrass staining. ( Thurlow archives.)


Well over the years this fresh water grass died off and was replaced with brackish marine grasses that formed a home for many fish and much wildlife, the IRL became “the most bio diverse estuary in North America.” Today with all the sea grass loss and pollution it is not holding onto that honor.

This UF link has a lot of great information of seagrasses in our area ( and it is important to know because if we have healthy seagrasses we will have a healthy river.

6 thoughts on “An Historic Look at Seagrasses, Indian River Lagoon

  1. Several years ago we had so much hydrogen sulfide coming off of the rotting seaweed that our sunroom ceiling turned black. Much of it came from longboard rotting with the sea grass. Marilyn ‘s silver tarnished badly.

  2. Interesting, Jacqui. The seagrass beds are hosts for thousands of fish and other life. It’s a disaster to lose them.

    Give the plane a rest one day and we’ll run by boat down to near Lox what good grasses are.

    The seagrass damage caused by discharges from Lake O is especially apparent when you look at the lush seagrass beds near by, such as Loxahatchee, Mosquito Lagoon, Sebastian, etc.

    Excess nitrogen and phosphorous pollution is recognized more and more for the problems they cause but industry lobbyists and influenced politicians won’t take significant steps to
    clean the waters.

  3. Millions of tons of seaweed recently washed up on our beachs and there was no stink. . The calcium peroxide( from the sand reacting to the acids in the sea weed) totally breaks down the seaweed to minerals and I think the salt must keep it from rotting. I would love to see if I could create the same conditions on rotting sea grass( in the river) that is on our beach by adding salt mixed with calcium sand. It would solve the stink problem.

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