| Fantail darter | |
|---|---|
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Perciformes |
| Family: | Percidae |
| Genus: | Etheostoma |
| Species: | E. flabellare |
| Binomial name | |
| Etheostoma flabellare |
|
The Fantail darter (Etheostoma flabellare) is a species of fish in the Percidae family, widely distributed across streams in North America.
Contents |
The fantail darter, Etheostoma flabellare, is a fairly common fish found across eastern North America.
It is well developed for stream life, and is adapted to the environmental changes that occur in streams as the seasons change. Changes can include the loss of microhabitats, when the fish will have to drift downstream to find another,[1] and also include changes in oxygen levels due to pollution or weather.[2]
Fantail darters provide paternal care for their eggs.[3] At spawning time, the female darters look for males that are already guarding eggs, which has led to the evolution of egg-guarding mimicry in males.[4] Even though the males guard the eggs, studies have shown that they exhibit filial cannibalism, meaning they eat some of the eggs in their nest.[4]
The fantail darter (Etheostoma flabellare) is a fairly common fish found in eastern North America. This will describe what is hoped to be an effective management plan for the fantail darter. Unlike some other fish species, from the time they are young, fantail darters have extensive vitelline plexuses, a network of veins that unites the yolk sac and the sinus venosus. They are also well-developed when they first feed. [5] This allows them to begin feeding on aquatic insects quickly, so they have no need to drift farther down the stream to find small planktonic prey. [5] The fantail darter is well developed for stream life. As the year goes on and the weather changes, the stream they live in may exhibit changes as well. Changes can include the loss of microhabitats, in which the darter will have to drift downstream to find another. [1] These changes in the stream can also include decreasing oxygen levels brought about by either pollution or weather. [2] Fantail darters provide paternal care for their eggs. [3] When spawning time comes around, the female darters look for males that are already guarding eggs, meaning the males need to have something that allows them to look like this. [4] Even though the males guard the eggs, studies have shown that they exhibit filial cannibalism, meaning they eat some of the eggs in their nest [3]. Since the fantail darter is a common species, there is no management plan currently in place for this fish. When taking into account a new management plan for these fishes, one should look at and manage for several factors that influence the lives of the fantail darter. First off, they eat small insects from the time they become developed for feeding. Secondly, as the stream changes, the habitat of the fantail darter can change. Lastly, how the fantail darter breeds is another key factor to an effective management plan.
The fantail darter is distributed across much of eastern North America. From the Great Lakes and the Mississippi River basins to South Carolina and northern Alabama, this darter can be found in small streams. They can be found as far west as northeastern Oklahoma. [6] This darter, like many others, lives in smaller streams. Due to their breeding habits, they are found in areas of the stream where there are cobbles and flat stones. [4] These fish are especially abundant near large slabs of limestone or shale. [7] Partly because of their wide range of habitat, the fantail darter has not been labeled as endangered.
Similarly to other darters, the fantail darters have several predators. For this reason, the male darters exhibit “egg mimicry”, which will be discussed later. The darters are also well colored for their habitat, and they blend in easily with the surrounding stream bed and rocks. From a research study collecting data on the fantail darter, it was found that all the males are in fact cannibals. [3] That is, they eat their own eggs. Some males will eat the entire nest of eggs, while others will eat only part of it. However, even though they are cannibals, they also have other means of food. Depending on the size of the specific darter, they can eat anything from tiny insects to larger insects and midge larve.[7] Their food source can include mayflies, caddisflies, dipterans, copepods, cladocerans, amphipods, isopods, hydrachnids, and gastropods. The larger fantail darters can include the larger type of insects including mayfly and midge larvae. [7] The fantail darter is primarily a benthic invertivores, therefore, they inhabit microhabitats which are found in shallow, low-velocity areas of the stream known as riffles. [1] If the microhabitat is destroyed or all the resources are used up, the fantail darter will simply move to another where more food can be found. [1] During the summer months, the water temperature of streams rises significantly, causing the water to have a lower oxygen level. [2] Fantail darters have a good tolerance for this temperature change and low oxygen levels. [2] With higher temperatures, water in the steams will evaporate quickly. The fantail darter has actually adapted to this, and is sometimes found to evacuate a drying riffle. [1] Even though, the fantail darter has a fairly good low oxygen tolerance, there comes a point when too little oxygen is harmful. This could be a cause that needs to be looked at in terms of managing this species. Without oxygen in the water, the fish will die out eventually. Low oxygen levels can be caused mainly by pollution to the stream. Pollution can also kill off the small invertebrates that the fantail darter consumes.
The life of a fantail darter starts at spawning. The fish spawn in early summer, when water temperatures reach 17-20°C. [5] Other darters, such as the logperch and rainbow darters, spawn at least a month before the fantail darter does. [5] From this we can assume that the fantail darter needs warmer temperature waters before it can spawn, and thus the eggs tend to be larger. [5] Fantail darters have an interesting growth period in that they do not really have a larval stage; instead, they start to feed 2-3 days after hatching. By this time the medial fins are differentiated.[5] They are born large, with well-developed heads, jaws, and teeth. [5] When first hatched, the free embryos are benthic and rarely go into the water column.[5] Fantail darters also have extensive and well-developed vitelline plexuses from the time they are very young, which allows them to feed on bigger prey quickly. This means that they have no need to drift farther down the stream to find small planktonic prey as early young.[5] As the darters grow and mature they take on the characteristics of their sex. Fantail darters mature and become of breeding age in one to two years, and usually do not live longer than four years.[1] The males of this species have a modified first dorsal fin, that characteristically looks like little bulbs. This is believed to be used for egg mimicry purposes. Females are proven to be more likely to spawn with a male that already has a clutch of eggs. [4] This may have led to an evolutionary change of the specialized egg-mimicking morphology in males. [4] Since the male already looks like he has eggs, the female will come under the rock that he has cleared a space for and will lay her eggs on the underside of the top rock; usually there are several females to each male’s clutch[4], thus there is more chance for diversity and offspring produced. Throughout the time of egg growth, the male will take care of the eggs[4];although, he may eat some of them to keep up his energy.[3] These nests can be easily disturbed, and the delicate eggs can be destroyed simply by a human walking through the stream, yet another potential risk in the fantail darters life.
There are currently no management plans in place for the fantail darter as it is fairly well distributed with good population sizes.
Although not currently risking extinction or even endangered, the fantail darter should be managed so that this risk can be avoided in the future. After examining the fantail darters closer one needs to look for an area where something may go wrong in the future to create an area of focused managements. If, for instance, the rock bed of the stream is disturbed, this could create the little nooks in which the females lay their eggs to not be there anymore. Without this, the females have nowhere to lay their eggs, the males cannot care for them, and thus no offspring are successfully produced. If, however, the female still lays her eggs without the males nest, the eggs now risk heavy predation. There are many other circumstances that may cause a need for population management of the fantail darter, such as pollution of the stream, non-native species invasion, or even human invasion of habitat. To avoid future diminishment of this species, the streams they live in should be managed and protected. To do this do not allow human’s to develop near the streams, keep the area upstream clean of harmful substances such as waste water plants. Even though the fantail darter does not need to be managed at this time, periodic sampling of the species should occur to determine if management is needed. To do this, one could simply take out a sampling net, get in the stream or river and collect and count specimens. This should probably be done biannually and completed in several areas in each state to keep the population of fantail darters in check. Should an area come under concern for low populations, research should be conducted to see what exactly is causing the dropping numbers. Next, areas that are critical habitats should be protected. Lastly, the general public should be informed about what is going on. This can be done using flyers or posters hung around campgrounds and national parks where the fantail darters are native. Whether the issue is not enough food or problems with the habitat, only after you discover the initial problem can the darter become effectively managed.