Indian River Lagoon Seagrass Loss

Following years of improving health and increases in seagrasses in the Indian River Lagoon, the 156-mile-long estuary is at a crossroads.

People have long been attracted to the lagoon by its unique features — its vast diversity of marine life and fisheries, plants and animals; temperate climate; accessibility and direct links to the Atlantic Ocean.

Those characteristics have changed over the last century and particularly within the last 50 years. Evidence of such changes comes in the form of fish kills, algal blooms and poor water quality. Although the lagoon can absorb a certain amount of pollutants, this capability has limits, and natural events, such as unusual weather, can combine with pollutants to cause an overload and undesirable consequences.

In spring 2011, an algal “superbloom” occurred in the Banana River Lagoon and ultimately spread into the northern Indian River Lagoon and farther north into the southern Mosquito Lagoon. This intense phytoplankton bloom covered approximately 130,000 acres and led to a noticeable reduction in water quality. Concurrently, a lesser bloom extended from just north of Melbourne south to the Vero Beach-Fort Pierce area.

Both blooms reduced the amount of light reaching seagrasses. Approximately 47,000 acres of seagrasses were lost, a reduction of about 60 percent. The concentrations of these blooms, the duration, extent and the resulting loss of seagrasses far exceeded any documented or remembered events. The magnitude of the seagrass loss is alarming because seagrass is an indicator of the lagoon’s health, a food source for manatees and a place of forage for a variety of fish and other marine life.

Also in summer 2012, a brown tide bloom began in the Mosquito Lagoon and moved into the northern Indian River Lagoon near Titusville. Compounding concerns are the mounting losses of manatees and pelicans since July 2012 and bottlenose dolphins since January 2013. State biologists are investigating the deaths of approximately 100 manatees, between 250 to 300 pelicans and 29 bottlenose dolphins to determine whether there is a link to the algal blooms or the loss of seagrass.

The future of the lagoon is important not only in ecological terms, but to the region’s economy. In those terms, the 2011 seagrass loss represented a potential reduction of $235 million to $470 million in commercial and recreational fisheries value in 2012.

Why did the superbloom occur? Many factors were in play, elements that may have contributed to a “perfect storm” of sorts. Preceding the blooms, long-term droughts had increased salinities in the lagoon and extremely low water temperatures occurred during the winters of 2010 and 2011. These extreme climatic events in conjunction with chronic, decades-long nutrient enrichment may have favored certain algae species that had previously never reached bloom proportions. While no single factor explains the cause of the phytoplankton superbloom, it is likely that these and other events contributed.

The St. Johns River Water Management District, Indian River Lagoon National Estuary Program, federal and state agencies, local governments and educational institutions are collectively working to find answers to the possible causes of the superbloom and to identify what, if anything, can be done in the future to limit or avoid a similar event. Research partners are investigating the possible causes of the blooms and developing strategies to reduce their magnitude, duration and frequency. Chief among this work is the Indian River Lagoon 2011 Consortium and the District’s Indian River Lagoon Protection Initiative. The Initiative is being developed to better understand the sources, cycling and transport of lagoon nutrients and the long-term impacts from the loss of the lagoon’s seagrasses, as well as potential strategies aimed at restoring the lagoon to a vibrant seagrass-dominated ecosystem.

The current and planned work builds on years of collaborative research and successful projects that have included:

• Cost-share stormwater projects that capture pollutants and sediments before they reach the lagoon
• Large regional projects that include dredging muck from major rivers and creeks to the lagoon
• Coastal wetland restoration projects
• Water quality and sediment studies by several state agencies and educational institutions
• Seagrass mapping and monitoring by the District
• Water quality monitoring by the District
• Monitoring of fish populations by the Florida Fish and Wildlife Conservation Commission’s Florida Fish and Wildlife Research Institute

The District sponsors the Indian River Lagoon National Estuary Program, which works with a network of partners and has implemented more than $80 million in projects over 20 years to improve habitats and water quality in the lagoon.

Since 1999, the lagoon program also has assisted local governments secure grants for lagoon restoration efforts. This program has brought an additional $200 million in capital improvements and preservation dollars into the lagoon region.

The coming summer months could herald a slow recovery of this unique ecosystem or a continued decline. Scientists, biologists and many other stakeholders are redoubling their efforts to determine strategies for improving the long-term health of this waterway.

For more information about the Indian River Lagoon and the current issues being investigated and addressed, visit floridaswater.com/itsyourlagoon.