Studies show Lagoon grass gained 12 percent

The Indian River Lagoon has grown a bit grassier, according to new data released this week.

Seagrass increased by 4,700 acres, or 12 percent, between 2011 and 2013.

Still, the bottom plant that provides a key barometer of the lagoon's overall health remains well below what it was just two years before an algae "superbloom" struck its deadly blow and killed some 47,000 acres of seagrass.

New data from the St. Johns River Water Management District shows seagrass coverage in Volusia, Brevard and Indian River counties is still 39 percent less than what it was before the 2011 superbloom.

Seagrass grew from just over 38,300 acres in that region in 2011 to more than 43,000 acres last year.

But the increase may only reflect normal year-to-year variation, district officials said.

"It's a good indicator, but we're cautious in that it's only one year," said Hank Largin, a district spokesman. "We'll have to see the longer-term data."

District scientists also have yet to determine how much the improvement may have continued this year.

The superbloom triggered a 60 percent loss of lagoon seagrass. That loss is suspected to have contributed to subsequent manatee, dolphin and other wildlife die-offs.

Seagrass is the lagoon's prime nursery for fish and other marine life that helps drive $3.7 billion in annual economic activity.

Just two years before the 2011 superbloom, lagoon seagrass thrived at levels not seen since the 1940s. Restoration efforts finally seemed to be paying off, with some help from drought, which meant less polluting runoff into the waterway.

But drought, coupled with record cold winter temperatures, also was among the major driving factors that fueled the superbloom and subsequent brown algae blooms, according to scientists at the University of Florida and the district.

Extreme cold in December 2010 and January 2011 killed tiny marine organisms that graze on algae, allowing the superbloom to thrive, the researchers concluded in a recent research paper published last month in the journal Estuaries and Coasts. Drought also drove lagoon salt levels into the ideal range for the algae species that bloomed in recent years, the researchers concluded.

As part of ongoing research, the water management district uses aerial photography to create seagrass maps of the lagoon. Photos are taken every two or three years to update the maps.

Biologists also dive along the seagrass beds to verify information from the aerial photos.

Contact Waymer at 321-242-3663 or jwaymer@floridatoday.com Follow him on Twitter @JWayEnviro

Indian River Lagoon seagrass gain from 2011 to 2013 (Volusia County through Indian River County)

2013 — 43,083 acres

2011 — 38,320 acres

Increase — 4,763 (12.4 percent)

Source: St. Johns River Water Management District