[USA] A widespread red tide outbreak is occurring along the Alabama coast.
In some places south of Dauphin Island this week, the water is stained blood red in patches that measure up to a half mile across. It is likely the worst red tide outbreak off Alabama in more than a decade.
The possibility of respiratory irritation among coastal inhabitants is predicted to be high in some areas, according to a National Oceanic and Atmospheric Administration website that forecasts harmful algal blooms. The possibility is highest along Baldwin County’s Gulf beaches and interior bays. State officials have closed all shellfish growing beds in Mobile and Baldwin Counties due to the outbreak.
Red tide is caused by a microscopic algae called Karenia brevis, which is common in the Gulf of Mexico and affects south Florida beaches every year, often for months at a time. It is somewhat rare off the Alabama coast. It can be toxic to fish and other marine organisms and cause breathing difficulties for people and animals exposed near the coast when large blooms occur.
The human exposure occurs when the bacteria is aerosolized in breaking waves. Due to relatively calm conditions along Alabama’s beaches during the early part of the outbreak, which began a week before Thanksgiving, exposure problems have been limited. With winds increasing to 20 knots or more for the next several days, and waves up to 7 feet high, scientists say that may change.
The name “red tide” comes from a distinctive reddish stain seen where the plant-like organism is present. Depending on the concentration of algae present in the water, the color varies from a gold tint to a muddy brown, or, in the most extreme incidents, a blood red. During a survey of Gulf waters Tuesday, an AL.com team encountered dense swaths of red tide over a broad area surrounding Gulf Shores, from the beach out 10 miles. A Dauphin Island Sea Lab encountered patches as far west as Horn Island. In some cases, the Gulf water appeared rusty brown, as if it was heavily stained with red clay.
“I have a container of water that is blood red. That’s from the area around the Triple Rig,” said Allison Robertson, a harmful algae specialist with the Dauphin Island Sea Lab. The area she referred to, near the Triple Rig is about 12 miles southeast of Fort Morgan. “That’s where the bloom was the most dense. That’s pretty intense… these cells are extremely fragile. They have relatively thin walls, so they burst really easily when they get in a surf zone. When that happens, it causes severe respiratory distress. So it affects not just shellfish growers, but the tourism industry.”
She said that the wind has been pushing patches of the bloom inshore, into Mobile Bay, in the last week.
There have been isolated reports of fish kills, and sick fish have been observed at a number of locations in Mobile Bay. Because red tide is a neurotoxin that affects the central nervous system, animals that have been exposed sometimes display a distinctive circular swimming pattern. I saw menhaden in Weeks Bay swimming in tight circles on Sunday, with some of the fish repeatedly bumping into the hull of my boat. Alewives were filmed swimming in drunken circles on the western shore of the bay the same day.
“The Department of Public Health closed the growing waters of Alabama as a precaution. We’re not really seeing much around Cedar Point, the main growing reef, but it is very pronounced in the samples in the Gulf around Dauphin Island and the Baldwin County beaches,” said Chris Blankenship, director of the Alabama Marine Resources Division. “We are continuing to work with the health department and the FDA to monitor those levels. When it leaves the area and the levels drop to acceptable standards, we will reopen the shellfish areas.”
Consuming oysters that have been feeding during a red tide incident will can cause intestinal illness, with diarrhea, nausea and vomiting. Scientists say cooking does not destroy the red tide toxin. Neither does freezing. However, fish that are caught in areas with red tide are usually fine to eat, provided they are fileted rather than eaten whole. The dinoflagellate that causes red tide accumulates in fish guts, which are discarded. But, authorities warn people to avoid eating fish that appear sick.
Blankenship said that state officials first detected the presence of red tide from oyster samples collected on Nov. 16. At the time, officials were conducting water quality tests to determine if it was safe to reopen Portersville Bay reefs after recent rains.
“The state reefs opened on Nov. 16 at Cedar Point. Then the health department got the red tide in their samples that day,” Blankenship said, noting that no contaminated oysters were sold to the public thanks to the state’s new oyster management protocol. Under that system, oyster fishermen must register each sack of oysters they harvest with the state before it can be sold.
“We were able to round up those bags. They had only gone to three shops. That’s where having the oyster management stations was so successful,” Blankenship said. The confiscated oysters were returned to the reef. Once the red tide has dissipated, those oysters will cleanse themselves of the toxin.
“This quite common off south Florida and Texas, but it is really quite rare for Alabama,” Robertson said. “Those places have warmer water, and more anthropogenic inputs, which means more nutrients to feed the blooms.”
There are historical reports of red tide incidents along Florida dating to the 1700s, but scientists have come to believe that pollution, particularly from sewage and fertilizers, plays a role in the persistent blooms seen today in Florida.
“This bloom actually began in Florida. It started around Panama City and Port St. Joe. I was collecting samples and dead fish near Destin five weeks ago. I expected it would get here much faster. The warm weather has helped it survive,” Robertson said. “Our main goal is to get as many samples as we can. If this becomes more common around here, we would like to be more on top of it.”
Robertson said that red tide blooms may not appear red. The color intensifies depending on how much of the algae is present. “People may be in a red tide bloom and not realize it because the color is lighter,” she said.
Robertson said the cold front pushing into the area should help break it up.
“If we have north winds, they will push everything south. That’s a good thing. It will put it in some water that has less nutrients. That should help,” Robertson said. “This has been a really big bloom. The fact that you saw it east of Gulf Shores at the same time we were seeing it way over here tells you how widespread it has been.”
View original article at: Red tide invades Alabama waters, shuts down fall oyster harvest