Feds add to endangered species list as biologists work to save the lady fishers
By Ben Raines
October 9, 2012
Three hundred orangenacre muckets, their delicate shells the color of warm caramel, sat nestled in a wet towel by the edge of Tallatchee Creek.
A team of scientists stood nearby. They studied the clear, shallow creek and decided that a series of fast runs looked like prime mussel habitat.
The mussels, hand-reared at the Alabama Aquatic Biodiversity Center and fitted with tiny identification tags, represent the best hope for rescuing their species from extinction.
Alabama is the undisputed king when it comes to freshwater mollusks like the orangenacre. There are 182 species of mussels living the in the state’s rivers. No other state comes close. In fact, nowhere else in the world comes close in terms of the number of mussel species living in a single river basin.
The state is home to wartybacks, heelsplitters, blossoms, papershells, pimplebacks, fuzzy pigtoes, sugarspoons, riffleshells, leafshells, and the list goes on and on.
But Alabama tops another list, this one the list of mussel species being lost to extinction. Every year, the U.S. Fish & Wildlife Service lists a few more Alabama mussels as extinct. Dozens are already gone forever.
On Tuesday, the U.S. Fish & Wildlife Service added 8 more mussels found in Alabama to the list of creatures protected under the Endangered Species Act. The mussels were added in response to a petition from the Center for Biological Diversity. The species have been candidates for federal protection since 2004.
The 2011 petition suggested more than 100 species in Alabama and Mississippi as candidates for federal protection. That's in addition to 123 species in Alabama and 44 in Mississippi already considered threatened or endangered.
Federal officials also designated 1,500 miles of streams in Alabama and Florida as critical habitat for the mussels. Streams in Barbour, Bullock, Butler, Coffee, Conecuh, Covington, Crenshaw, Dale, Escambia, Geneva, Henry, Houston, Monroe, and Pike Counties earned the new designation. That habitat designation will also protect rare fish and snails in those watersheds.
Two of the newly protected species, the Alabama pearlshell and the southern kidneyshell have disappeared from more than half of the creeks they used to live in. The round ebonyshell is now found only in the main channel of the Conecuh River.
That’s where Paul Johnson and the biologists at the biodiversity center come in. Think of Johnson as the Johnny Appleseed of mussels. In the last few weeks, scientists have placed five different species of threatened mussels reared at the biodiversity center into five different rivers. The goal of the program is to rebuild spawning populations of various species in as many locations as possible.
That way, if a mussel population in one river or creek suffers a killing dose of industrial pollution or suffocates under a choking load of muddy runoff from farms or construction sites, a whole species won’t be lost forever.
“Mussels are basically the rivers’ filters. Each one is capable of filtering a gallon an hour,” said Johnson, wading a knee deep riffle in the Tallatchee. Moving upriver, he paused every now and then to plant a few of the live orangenacres in little clumps on the creek bottom. The animals like moving water and sandy, pebbly bottoms.
“When you had densities of hundreds of thousands to millions of animals in each river all over the state, they literally were the most important component in maintaining the water quality of our rivers,” Johnson said.
Historical records from across the state, some dating to the early 1800s, describe the remarkable clarity of the rivers. It was not uncommon to be able to see carpets of mussels along the river bottom in eight or ten feet of water, according to those accounts. Their shells came in purples, greens, blues, and even caramel, like the orangenacre.
One species, the washboard, grows as large as a dinner plate. They can live to be 80 to 100 years old. A native fat southern mucket mussel, found in Tallatchee Creek as the orangenacres were planted, was estimated to be about 20 years old.
But those giant shoals of decades old mussels that were present through the 1950s are mostly gone today. So too is the clear water the mussels helped create by filtering out silt, algae and other water-clouding particles. Today, in most of the rivers, it is seldom possible to see more than a foot or two underwater.
It was not pollution from steel mills or chemical factories that did the mussels in. Nor was the once thriving mussel fishery in the state to blame, which harvested the shellfish for buttons and for the freshwater pearl industry.
The most potent factor behind the decline of Alabama’s mussel species are the dams built on the major rivers, Johnson said.
The Coosa River dam alone is believed to have caused more aquatic extinctions than any other factor in the history of the United States. The problem, Johnson said, is that mussels simply can’t live in the big lakes that pool up behind the dams. Millions upon millions of mussels died across the state when the rivers and creeks they lived in were drowned behind the dams.
“Of the 182 mussel species in Alabama, there are 12 that can live in lakes,” Johnson said.
But the dams continue killing mussels today, by slowly wiping out the last populations of various species living in the creeks and rivers that flow into the dam lakes. Before the dams, the state’s smaller tributary creeks and rivers were all interconnected. Fish in one river could migrate to other rivers, and dozens of species made annual migrations hundreds of miles long.
Those fish migrations were key to the spawning method of mussels, for mussels are fishermen. In fact, said Jeff Powell, a U.S. Fish & Wildlife Service scientist, the species’ Latin name, Lampsilis perovalis, means “lady fisher.”
When a female mussel is ready to lay her eggs, a condition the scientists describe as being “charged,” she casts her lure into the water. Biologists light up when they talk about the lure, which is a mass of eggs that dangle in the current from the edge of a mussel’s shell.
“What’s unique about the orangenacre, its’ lure comes out on a long tether and it waves in the current and looks like a wounded minnow. The mussel, she’s waiting for a bass to come along and eat that minnow,” Powell said, cradling orangenacre number 62 in his hand for a moment before burying it partially in the river bed behind a sunken log.
“Each mussel requires a specific host species to carry out its life cycle. For the orangenacre, it is bass,” Powell said. “The female has encapsulated the baby mussels in that lure. A fish comes in and eats that lure. The female mussel then ejects those glocidia, the baby mussels, into the fish’s gills. They live on the gills for several weeks, until they are large enough that they drop off on the river bottom somewhere and live on their own.”
Some mussel lures look like fish, some like crayfish, and others like insects. By fishing in this fashion, mussel species were able to spread all around the state. Small populations of orangenacres are still holding on in a dozen or more counties in Alabama and Mississippi. But when creeks and rivers lose their water clarity due to muddy runoff from farms, construction sites and subdivisions, fish can't see the mussel's lures.
“We’re trying to reintroduce a self-supporting population at a new locality,” Johnson said of the ongoing work. “The home run is we come back in a year and see these animals are still here. Once we see they are still here, we will introduce more animals.”
The biodiversity center also raises some of Alabama’s rarest fish species for reintroduction in places where local populations have been wiped out.
“With Alabama, there are 182 mussel species in the state. It’s the most biodiverse place on the planet for these animals. And its not just mussels,” Johnson said. “It’s also snails, it’s also crayfish, and for temperate freshwaters, we have the highest diversity of freshwater fish on the planet. Alabama is an aquatic biodiversity haven, not only nationally, but globally… We’re trying to protect that, preserve it.”
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