More heartbreak for Biscayne Bay as schools of mullet were found just before sunrise gasping for breath on the waters off Albert Pallot Park on Saturday.

The dead fish could be seen floating on the Bay from the Haulover Inlet to North Bay Village and south to the Venetian Causeway.

“Oxygen dropped super fast between 6 o’clock and 11 o’clock,” Dr. Todd Crowl, director of the FIU Institute of the Environment, said. “Just like a pulse of something sucking the oxygen out of the water.”

It was low oxygen levels that caused the unprecedented fish kill in Biscayne Bay in August when we saw thousands of dead fish and other marine life floating on the waters and washing up on the shores for days. But unlike last time, water temperatures Saturday were normal and circulation in the Bay was better.

So what’s contributing to the problem?

“We really are down to what is coming off the land from the west, down the canals, down the Little River, down the Miami River into the Bay,” Crowl said.

For scientists it’s becoming clearer that what’s causing the kills are humans and the amount of land-based pollution constantly entering the water.

The Little River Canal is a big source of the problem. On a daily basis, tons of trash and pollution accumulates. A boom blocks most of it, but some of it gets through and flows down the canal to the flood gates. By law, the flood gates must be opened by Water Management whenever we get heavy rains. When that happens, all that pollution flows right into Biscayne Bay.

“To see this happening again, it’s just more heartbreak for the bay but it’s more motivation — motivating for all of us to make more change,” Dr. Rachel Silverstein, executive director of Miami Waterkeeper, said.

The latest catastrophic events are yet another indication that Biscayne Bay is in crisis.