Appalachian elktoe facts for kids
Quick facts for kids Appalachian elktoe |
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| Conservation status | |
| Scientific classification | |
| Genus: |
Alasmidonta
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| Species: |
raveneliana
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The Appalachian elktoe (Alasmidonta raveneliana) is a special kind of freshwater mussel. It's a small creature with two shells, like a clam. These mussels live in rivers and streams. You can only find them in North Carolina and Tennessee in the United States. They are part of a group called river mussels.
Contents
What Does the Appalachian Elktoe Look Like?
The Appalachian elktoe has a thin, kidney-shaped shell. It can grow up to about 10 centimeters (4 inches) long.
Younger mussels usually have a yellowish-brown outer shell layer, called a periostracum. Older mussels often have a dark brown or greenish-brown outer shell.
It can be hard to see the patterns on the outside of the shell. Sometimes, you might spot faint streaks or wavy lines. These are easiest to see on the top part of the shell. Most mussels have green waves that are tiny and blend in with the shell's color.
Inside the shell, the lining is called nacre. It has a shiny look, often white, blue, and silver. The middle part of the inner shell might change color. It can go from a light, see-through shine to a pink or tan color. Some mussels even have darker spots or blotches inside their shells.
Where Does the Appalachian Elktoe Live?
Even though the Appalachian elktoe is rare, we know a lot about its home. Its habitat is similar to other freshwater mussels.
Alasmidonta raveneliana mostly lives in shallow to medium-sized creeks and rivers. They like cool water that flows fast or at a medium speed. You'll find them where the river bottom has more rocks or gravel. They don't do well in areas with clay or silt moving in the water.
These mussels have been found in places with different sizes of rocks. This includes sand, gravel, and even large boulders. They prefer a mix of all three.
Appalachian elktoe mussels need a stable home to survive. They won't be found where gravel or rocks shift around a lot. This shifting can harm them.
Life Cycle and How They Eat
Many things about the Appalachian elktoe's life are still a mystery. It's hard to find them, and their numbers are shrinking. We don't know exactly what they eat or which fish they use as hosts. We also don't know how long they live. They are very sensitive creatures, which makes them hard to study.
Like other mollusks, the Appalachian elktoe eats by filtering tiny food particles from the water. We don't know their exact diet yet. But scientists think they eat the same things as other freshwater mussels. This includes tiny bits of dead plants and animals (detritus), tiny algae (diatoms), and tiny water plants (phytoplankton) and animals (zooplankton).
The way Appalachian elktoe mussels reproduce is also like other native freshwater mussels. First, the male mussel releases sperm into the water. When female mussels come across the sperm, they take it in through their siphons. This usually happens when they are breathing or eating.
Once the female has the sperm, she keeps it in her gills. Here, the baby mussels, called glochidia, grow and develop. When the larvae are ready, the female releases them into the water. Soon after, these tiny mussels find a host fish to live on for a while. When the mussels grow into juveniles, they let go of the host fish. Then they continue to grow on their own.
Not all mussels go through this stage. For the young mussels to survive after leaving the host fish, they need to land in a good spot. Only one fish species has been identified as a host for the Appalachian elktoe. This is the Banded Sculpin, or Cottus carolinae.
Where the Appalachian Elktoe Lives Today
The Appalachian elktoe is found only in mountain river streams. These are in western North Carolina and eastern Tennessee.
We don't have old records, but people believe these mussels once lived in a much larger area. They likely lived in bigger creeks and streams of the upper Tennessee River systems.
Today, the Appalachian elktoe lives in scattered groups. They are found in parts of the Little Tennessee River system. They also live in the Pigeon River system and the Little River in North Carolina. You can also find them in the Nolichucky River system in North Carolina and Tennessee.
In the Little Tennessee River system in North Carolina, they live in the main part of the river. This is between Franklin and Fontana Reservoir. This area is in Swain and Macon counties. They are also found in parts of the Tuckasegee River. This is in Jackson and Swain counties. They live from below Cullowhee down to Bryson City.
The groups of mussels in these rivers are very small. They range from just two live mussels to about fifteen. Usually, only two to four mussels are found together in one spot. The species is still very spread out. This makes it hard to find them, especially when there are so few in each place.
In the past, these mussels lived in more places. This included Tulula Creek and the main parts of the French Broad River and the Swannanoa River. But Appalachian elktoe mussels haven't been seen in these waters lately. It's thought they no longer live there.
It was also once thought that the species lived in the North Fork Holston River in Tennessee. But later studies found a similar mussel species there, not the Appalachian elktoe. It's still a bit of a mystery if they ever lived there. But even if they did, they are not there today.
By 1996, only two groups of Appalachian elktoe were known to be alive. One group was in the main part of the Little Tennessee River. The other was scattered in the main part of the Nolichucky River in various counties of North Carolina.
Why the Appalachian Elktoe is in Danger
The Appalachian elktoe was added to the Federal Register of Endangered Species on November 23, 1994. This means they are at high risk of disappearing forever. We don't know the exact reason for their decline.
Many things are thought to have caused their numbers to drop. This includes siltation (when dirt and sand build up) from logging, mining, and farming. Construction work in the area also causes problems. Water that runs off into the rivers, called runoff, can seriously hurt them. This is because these mussels need clean, oxygen-rich streams to live. Pollution from factories, farms, and cities can greatly damage these sensitive mussels.
Humans changing the mussels' homes also causes problems. Things like dredging (digging up the riverbed), building dams, and changing river channels hurt them. When river environments are changed without proper control, it harms not only mussels but most other freshwater animals too.
Mussels don't move much. They can't travel long distances. This is why they need very specific, stable places to live that meet all their needs. Their inability to move makes it hard for them to survive. They can't adapt to constantly changing water environments. When their home is always being disturbed, they can't grow and reproduce properly.
Scientists first noticed their numbers dropping after Hurricane Frances and Hurricane Ivan hit the Southeastern U.S. in the early 1990s. While these storms changed the land, natural storms don't usually threaten the Appalachian elktoe. But when people change the natural state of the streams, it becomes very hard for the Appalachian elktoe and other mussels to stay healthy.
Siltation in rivers is one of the biggest threats to freshwater mussels. Natural siltation usually doesn't bother them much. But siltation caused by human actions directly and indirectly harms mussels. It changes the natural flow of rivers. It can also create mounds on the river bottom. These mounds cover the rocks that mussels like to live near. They also create areas that are hard for the mussels' host fish to swim in. This causes the mussel groups to become separated.
Siltation also makes the water quality worse. It exposes mussels to more pollution than they would naturally face. A study in 1936 found that even a small amount of unnatural silt (just one inch) caused many mussels to die. This included the Appalachian elktoe. Young mussels and their reproduction are also seriously affected by even small amounts of silt. When their clean, oxygen-rich water gets too much silt, the young mussels can't develop well. This is because the silt clogs the gills of the host fish they live on. Most mussels are sensitive to many pollutants. Some of the most harmful are heavy metals, too many nutrients, and chlorine.
Because the Appalachian elktoe's habitat is so special, a large area was set aside. On September 27, 2002, over 144 miles (232 km) of river area in western North Carolina and eastern Tennessee were called "critical habitat". A critical habitat is an area the government protects to help save species living there. By calling the Appalachian elktoe's home "critical," it allows for special plans to be made. It also means there can be fines for activities that harm the mussels.
Plans to Help the Appalachian Elktoe Recover
In August 1996, a plan was made to help save these endangered mussels. It's a plan for the whole region. It includes all the areas where the species lives now and where it used to live.
The main goal of this plan is to remove the species from the Endangered Species List. Right now, the Appalachian elktoe is considered critically endangered. We don't even know if they are still actively reproducing.
When the plan was first made, the goal was to change the species from "endangered" to "threatened." This is a step towards full recovery. There are four main steps to help the Appalachian elktoe recover:
- The first step is to have at least four stable groups of Appalachian elktoe. These groups need to be in places where they used to live. This can happen by protecting existing groups or by starting new ones. Ideally, there would be one group in each of the Little Tennessee, French Broad, and Nolichucky River systems.
- The second step can only happen after the first one is successful. It is to have different age groups of mussels in these rivers. For a group to keep reproducing, there must be juveniles (young mussels), adults, and developing larvae (glochidia).
- The third step is to keep all the new mussel groups in stable and safe homes. This means checking the streams often. It also means protecting them from past threats and any new dangers that might appear.
- The fourth and final step is to keep all four groups stable. The hope is that their numbers will increase over the next ten to fifteen years.
For the species to be completely taken off the endangered list, more goals must be met. Instead of just four healthy, reproducing groups, there must be at least six. Like the first plan, ideally, there would be at least one group in the Little Tennessee, French Broad, and Nolichucky River systems.
The next requirement is to have at least three age groups in each of the six populations. This includes a full group of young mussels and females carrying eggs. This makes sure that reproduction is happening steadily. Once this goal is met, the next step is to make sure these groups' homes are safe. They must not be in danger or easily destroyed. Finally, like the fourth step in the first plan, the last goal is for all six groups to stay stable. They should also be steadily increasing in number within ten to fifteen years.
To take all these steps, some actions are needed. The first and most important action is to use legislation (laws) to keep the species protected. It's important to tell local and federal lawmakers about the endangered species. The public also needs to know. Education programs about mussels in the Southeastern U.S. are very important. They help save the Appalachian elktoe and other endangered mussels in the area.
Another very important action is to constantly check on the existing groups. It's also important to find and manage new groups that are growing. Checking on the species is key to recovery. But sadly, not much information has been gathered about the Appalachian elktoe. To fully benefit from the recovery plan, more information must be found. This is one of the most important actions needed.
Ideally, we will learn about the species' past records, what kind of home it needs, and what threatens it. By finding out things like where they used to live and what they eat, we can get valuable information. This will help us know how to save the Appalachian elktoe. Finding this information will also help create useful management plans.
The cost of the recovery plan was not known at first. Because there isn't much information on the species, we don't know exactly what funding is needed or how much. It's thought that the costs will go up each year over the ten to fifteen-year period. This is because as more research is done, hopefully more mussels will be established, which will need more money. The costs are also hard to figure out because mussels usually take five years to start reproducing. So, a full ten years is needed to study how they reproduce and what affects it.
Images for kids
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The Appalachian elktoe mussel.
See also
In Spanish: Alasmidonta raveneliana para niños
