Algae Blooms in Biscayne Bay Killing Local Species

FIU's CREST CAChE deploying water research bouy into Biscayne Bay. Photo from FIU Flickr.


By: Joshua Ceballos / Staff Writer

The Biscayne Bay is the crown jewel of the University’s North Miami campus. Its calm waters are a venue for relaxation, recreation, and research, but they’ve been in serious danger for the past 10 years, and they’re not getting any better.

Last December, a sewage leak near Edgewater led to a water warning for parts of Biscayne Bay, as reported by CBS 4. Not even a year later, on Sunday, Aug. 11, 2019, a ruptured sewage pipe spilled over a million gallons of “raw human waste” into the Oleta River, which flows into Biscayne Bay.

The week before classes began, University President Mark B. Rosenberg directed the deans and faculty at the Biscayne Bay Campus to do something to help fix the Bay, because recent developments in the water have been grim.

“We have no choice—so much depends upon our ability to muster all our resources and get on with the task of healing our fragile marine environment. Our Biscayne Bay needs our help,” said Rosenberg in a written statement.

The problem of the Bay can be boiled down to one main issue: what was once a pristine, clear water ecosystem is going the way of many water sources in the southeast U.S.– it’s getting murkier, according to the Director of FIU’s Center for Coastal Oceans Research, Jim Fourqurean.

Biscayne Bay is a clear water ecosystem that supports a variety of seagrass life close to the shore. That seagrass is an integral part of what makes the Bay special and what keeps it healthy.

“Seagrasses are very productive plants, they’re called a foundational species,” Fourqurean said. “Much like trees in a forest, seagrasses form the structure that other species live in.”

The seagrasses in the Bay– which keep the water clean, serve as homes and food for sea creatures, and keep the soil on the shore from eroding– have been dying off for over a decade. 

A recent study by the National Oceanic and Atmospheric Administration looked at the water quality and seagrass health in Biscayne Bay from 1995 to 2014. The study found seagrasses have been dying in major events in the northern parts of the Bay where the Biscayne Bay Campus lies.

Fourqurean cited this study when he says the northern sections of the Bay are no longer supporting the seagrasses that keep them healthy.

“The water quality near BBC is the worst… seagrasses are no longer being supported in the top half and they’re dying from North to South,” Fourqurean says.

What’s causing this marine plant life genocide? Phosphorus. The chemical found in fertilizers and human waste.

Phosphorus is one of the two main chemicals in agricultural fertilizers, and its main purpose is to boost the growth of plant life it comes into contact with. In the case of the Bay, that plant life the phosphorus is boosting is algae.

According to the NOAA report, the northern part of Biscayne Bay had higher than normal levels of phosphate (a chemical containing phosphorus) and chlorophyll. This means that the waters near BBC have higher levels of algae that cloud the waters and kill the native seagrass.

“As the algae grows, the water gets murkier so the seagrass doesn’t get enough sunlight. With no seagrass, the soil is loose so it gets thrown up easily and makes the water even murkier. It’s a vicious cycle that will change the environment completely,” says Fourqurean. 

Basically what this means is that what is now a mostly beautiful and crystal clear bay will look like a swamp before long.

Although phosphate is usually associated with agriculture, the main source of the chemical is Biscayne is septic tanks and sewage, according to Fourqurean. There are so many people in Miami now, that we’re filling ground and surface water sources with phosphorus.

“Until we get a handle on the water quality degradations caused by the people in Miami, we won’t be able to fix the issue.”

This story is the first installment in a series about the Biscayne Bay.

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