Culprit in Lakewood Ranch fish kill seems to be algae

kmoschella@bradenton.comJuly 16, 2014 

LAKEWOOD RANCH -- Summerfield and Riverwalk residents were assured by district supervisors Tuesday there are no unusual problems or dangerous issues facing their stormwater retention ponds following anonymous allegations of a fish kill over the Fourth of July weekend.

Lakewood Ranch Operations Director Ryan Heise told supervisors the situation is under control and appears connected to a pond near Primrose Circle with chronic low-oxygen levels and algae blooms.

"We installed a new solar aeration system in the pond where dead fish were reported, but we saw no evidence of this. Algae blooms and fish kills are common, and the whole intent is to have them develop in our stormwater systems before they reach the Braden River or Sarasota Bay. This particular pond has a chronic problem with algae blooms and it's set back by a nature preserve," Heise said during a monthly supervisor meeting.

"A few years ago, we had an unusually hot summer and then the temperature dropped dramatically after a big storm and we had a huge amount of dead fish, which the trash man didn't

appreciate," Supervisor Alan Roth joked.

According to the Florida Fish and Wildlife Conservation Commission, too little oxygen in the water is the primary cause of fish kills in Florida. When pesticides, herbicides or fertilizers are applied prior to heavy rains, chemicals washed into the water may also kill the fish.

Heise said he took water samples early Monday morning and oxygen levels were dangerously low. But after the normal process of photosynthesis during the day, when the sun replenishes oxygen in the pond, levels were back to normal when he tested later in the day, Heise said.

The operations department has seen an increase in requests for lake maintenance due to an influx of algae in retention ponds, which is normal this time of year, Heise noted.

Solar aeration is one of a number of sustainable methods used to maintain ponds in Lakewood Ranch and prevent rapid reproduction and spread of algae. Another means of curbing algae bloom, Heise said, has been the introduction of herbivorous fish called triploid grass carp, whose diet consists almost entirely of aquatic plants, including many types of submerged vegetation. The carp have been stocked in permitted ponds in districts throughout Lakewood Ranch.

Heise created a new video in his online series, "Ryan's Ranch Roundup," to inform residents dog waste can also seep into stormwater ponds and do a lot of damage.

"Four out of 10 households have dogs, and 38 percent of households don't clean up after their pets," Heise says in the video, which urges residents to clean up after their pets.

All Lakewood Ranch community development districts can review stormwater retention and other pond issues when the community's lake maintenance company contract comes up for renewal next month.

Lakewood Ranch Executive Director Eva Rey said researchers from the University of Florida who conducted a stormwater information survey last winter among residents will hold a Town Hall meeting at 2 p.m. July 30 to discuss the survey. Rey said all residents have been emailed about the meeting.

Kathryn Moschella, Lakewood Ranch reporter can be reached at 941-745-7010. Follow her on Twitter @MoschellaHerald.co

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