| The President’s Hoot by Richard H. Baker, Ph.D. May 2006 |
What has caused our sea grasses to become endangered in the Indian River Lagoon (IRL)? In doing research on fish houses on the IRL, I came across a newspaper article where Mr. Charles Sembler Sr., told a reporter that the decline in fishing in the Indian River began when the river channel (Intercoastal Waterway) was dredged in 1952. “He indicated that boat traffic in the river increased substantially, as the population density increased from Melbourne to the south. Outboard motors created much of the destruction of the grass meadows in the river (Press Journal, September 17, 1994). This trend continues elsewhere even to day. With the increase in Florida’s population since the 1950s, Florida’s seagrass has declined from 5 million acres to only 2 million acres.
Seagrass decline is also due to stormwater runoff (containing chemicals, fertilizers, silt and debris from yards and agricultural), dredging and building marinas and docks. Seagrasses are marine plants that require light to carry out photosynthesis. Docks and marinas shade out seagrasses so that they cannot grow. Nutrients from lawn and agricultural runoff cause microscopic algal blooms in the water column, and dense epiphytic algal growth on the seagrass blades, blocking out the light that seagrasses need to grow.
Why should we care about seagrasses? The shallow-water seagrass meadows are the most important critical habitat in our Indian River, essential for our ecology and our economy. They provide food, habitat, and protection for most of our fish and other animals including manatees, sea turtles, and wading birds.
Today prop dredging continues to damage our underwater seagrass beds, greatly affecting the productivity of our Lagoon, especially our commercial and sport-fishing industries. Boat propellers can rip up seagrasses and dig trenches that create barren areas where fish and other animals once flourished. These ruts require up to 10 years or even more to recover.
According to the St. Johns River Water Management District, one of the most productive and diverse seagrass areas in the IRL occurs around the Oslo Rd/ Oslo Riverfront Conservation Area in south Indian River County. All seven species of seagrasses (Turtle-grass, Widgeon-grass, Shoal-grass, Manatee-grass, Johnson’s sea-grass, Star-grass, and Paddle-grass) are found in the shallow waters there. Dr. Grant Gilmore, our speaker this month, says the abundance of Shoal-grass in particular near the old Oslo Dock is a major reason why the spotted seatrout uses this area as a nursery. This area is very shallow and will not take large boat motors. See chart of Oslo seagrasses below.
Yet the county has proposed 4 new docks (2 over 120 ft long) and a new ramp at Oslo Rd/ORCA. The county proposes no new dredging of an old channel. I am concerned that this will encourage larger and larger boats that in turn will damage even more of the best seagrasses we have in Indian River County. There are today available boat ramps in South County for large boats only 10 minutes away from Oslo Rd. Thus, it makes no sense to spend county money to build larger docks and ramps for larger boats that will not be able to get out to the Intercoastal Waterway without prop dredging and killing the seagrasses that provide fish for our sport fishers when proper facilities are available.
