Wildlife officials say a massive fish kill in Louisiana was not caused by oil from the BP oil spill.
Low tide and high temperatures caused low oxygen levels that suffocated huge numbers of fish in Plaquemines Parish, Louisiana, a spokeswoman for the Louisiana Department of Wildlife and Fisheries said Wednesday.
Department biologists found the fish kill in Bayou Chaland had nothing to do with the Gulf of Mexico oil spill, Olivia Watkins said.
After the dead fish were found on Friday, Plaquemines Parish President Billy Nungesser asked for an investigation, because oil from the BP spill had affected the area.
Watkins said the area is bounded on one side by a rock dam, with a shallow pass to the Gulf of Mexico on the other.
"When the tide is low, it becomes a pool," she said. "We had a low tide and all the fish got trapped" in water less than 2 feet deep.
Hot water holds less oxygen than cold water, and heat speeds metabolisms so plants and animals need more oxygen. The fish suffocated because the water held too little oxygen to keep them alive, Watkins said.
Such fish kills are common in Louisiana's shallow waters in late summer and early fall.
The heat also contributed to low oxygen levels that killed starfish-like creatures called brittle stars which washed up along parts of Barataria Bay earlier last week, Watkins said.
Brittle stars live on the bottom, where oxygen levels drop first, and cannot swim up out of the low-oxygen areas as fish can.