Elegant madtom

The elegant madtom (Noturus elegans) is a native Tennessee fish.

Classification

Until the 1990s and early 2000, Noturus crypticus and Noturus fasciatus were thought to be the same species as Noturus elegans. However, they are now considered distinct species. The chucky madtom, Noturus crypticus, is the only one of the three currently listed as severely threatened.^[1]

Geographic distribution

The elegant madtom is found primarily in upper and lower Tennessee Rivers and in Alabama, and those rivers are Roaring River, Green River drainage, Dunn Creek, TN, and Piney Creek, AL.^[2] The elegant madtom can be found at the Green River drainage and lower, north-central Tennessee rivers, an example is at Little Chucky Creek, Greene County,TN.^[3] The elegant madtom was also found in Alabama and in central Kentucky.^[4] However, the status of the elegant madtom is unknown in Alabama. Places that the elegant madtom has been found include the Roaring River, Little Chucky Creek, Green River Drainage (they have been found in the Green River Drainage in TN and in KY), Dunn Creek, TN, and Piney Creek, Paint Rock River, and Flint River, AL.^[2][5] N. exilis was misidentified at Bear Creek as N. elegans in 1996 in Alabama.^[2] This mis-identification could be a reason for a small decrease in the overall population size. According to surveys there are very low numbers of the elegant madtom in the middle and upper Tennessee River drainage. The survey reports that these low populations there could be because of the lack of available nesting sites. However, the elegant madtom is common in the Green River and lower rivers in Tennessee that are close to Alabama.^[2] The elegant madtom prefers habitats with riffles and rocks to nest under.

Ecology

The elegant madtom from immaturity to adult hood is an invertivore, which means it feeds on invertebrates.^[5] The elegant madtom is a species that should be listed as threatened. It is only common in a few places-the Green River Drainage being one of those places. Also the elegant madtom faces a threat from most fish that are larger than it is, such as the Large Mouth Bass or a Larger Catfish. However the elegant madtom does have a defense and that is its venom delivery system.^[3] The elegant madtom has a venom delivery gland that is in its pectoral and dorsal spines and the venom is secreted through these spines to hurt potential predators or competition.^[6] Competition that the elegant madtom faces is from salamanders, lizards, and some snakes that eat invertebrates. The elegant madtom prefers to live in small rivers and also like gravel-bottomed creeks. The elegant madtom also prefers for there to only be minor ripples in the stream in which it is inhabiting. There is little known about what abiotic factors influence where the elegant madtom will decide to nest. However if we look at a sister species in the same genus, Noturus baileyi which lives in a similar habitat, then we can project that the elegant madtom will prefer a pH of 6.2 to 7, and a temperature of 14.0 to 22.0 °C.^[7] Dams, uplands habitats and waterfalls are things that cause barriers for the elegant madtom to disperse.^[5] Therefore, humans could negatively influence the distribution of the elegant madtom the most by building dams, which would cut off their way to either move habitats or mate, or by releasing deadly chemicals, or very invasive fish into the stream, both of which could destroy small populations of the elegant madtom. The elegant madtom can be found most commonly underneath large rocks in rivers and creeks.^[2]

Life History

The elegant madtom matures within one year and dies within two years.^[7]

Within approximately a year after emerging from its egg, the elegant madtom will reach sexual maturity. Then after this year of growth a species of Noturus elegans will find a mate and make a nest beneath a rock in a river or stream. Rocks are very important for the elegant madtom because without this substrate to lay their eggs under they will never have the ability to lay an effective nest that they can protect. The average brood size for the elegant madtom is 50 eggs. Not very much is known about when the elegant madtom mates or how often in fact. However, it is estimated, from looking at a sister species, Noturus baileyi again, that mating takes place in the months of May to August and only once a year.^[7] The average lifespan for the elegant madtom is 2 years.^[3] After this time it will die. Other ways the elegant madtom can die are human induced, these are the construction of dams that can change how a river is structured and also when rivers are flooded this will ruin the habitat of the elegant madtom because it prefers shallow slow moving freshwater.^[8]

Current Management

In order for humans to decrease their negative impacts on the elegant madtom, before dams are built the rivers should be surveyed to see if the dam is within 10 km of a population of the elegant madtom and if the dam is, then the dam should not be built.^[8] Also electrofishing should not be performed anywhere close to where the elegant madtom has been found because Electrofishing kills all fish in the vicinity of the electric current.^[9] Currently there is no management concerning the elegant madtom. This is because the elegant madtom is not listed on the endangered or threatened federal or state lists.^[10] There are currently no agencies or non-governmental groups/organizations (NGO's) that are protecting the species. Also, there is no refuges or conservation easements that are providing effective areas for the conservation of the elegant madtom. It has been recommended by people who have done surveys on the fish that it should be listed as threatened but it currently is not listed as threatened.^[2]

References