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Tampa Bay’s seagrass beds to take big hit from rain-fueled algae blooms

Besides the standing water in yards and homes and the cars left half submerged in the streets, the constant rains over the past month are poised to claim another victim: Tampa Bay.

The rain runoff, much of which carries substantial amounts of nitrogen and other nutrients, wound up in the bay. The huge influx of nutrients is expected to result in algae blooms that will cloud the water, block the sun from reaching the bottom and likely kill off vast beds of seagrass, considered one of the key building blocks of a healthy estuarine system, environmental officials said.

“We are funneling an awful lot of storm water runoff into the bay,” said Tampa Bay Estuary Program spokeswoman Nanette Holland O’Hara. “There are lots of things in the runoff, mainly nitrogen loadings, which spark the growth of algae, turns the water green and consumes oxygen.

“I would not be surprised to see localized fish kills as well,” she said, “particularly in areas of the bay that have limited circulation, like upper Tampa Bay.”

A fish kill was reported along Bayshore Boulevard in Hillsborough Bay last week. State scientists were called in to test the water, but the results of those tests were unavailable Wednesday.

Seagrass beds, which flourish in less than 6 feet of clear water, are among the bay’s most vital habitats. The beds are important nurseries and feeding grounds for numerous species in Tampa Bay, including shrimp, spotted sea trout, red drum and snook.

The runoff’s impact down the road is unclear.

“We’ve had unrelenting runoff going into the bay,” O’Hara said. “In my lifetime, and everyone I’ve talked to says the same thing, I haven’t seen an event like this, with this kind of torrential rain day after day after day for weeks.”

In the winter of 1997-98, parts of Tampa received about 10 inches of rain in two days, resulting in an algae bloom that led to the loss of about 1,200 acres of seagrass in the bay, she said.

This year is much worse. Some local areas saw more than 20 inches of rain fall within a two-week period at the end of July and beginning of August.