| Golden topminnow | |
|---|---|
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Cyprinodontiformes |
| Family: | Fundulidae |
| Genus: | Fundulus |
| Species: | F. chrysotus |
| Binomial name | |
| Fundulus chrysotus (Günther, 1866) |
|
The golden topminnow, Fundulus chrysotus, is a fish of the genus Fundulus and is a United States native fish mostly distributed throughout the southeast; ranging from Kentucky and Ohio south into Florida. Although it has such a wide distribution throughout the south, the habitats and micro-habitats that it occupies do not differ much from one area of distribution to others. The Golden Topminnow is a small surface feeding fish that tends to reproduce late in the spring season and on into the early parts of the summer, and although the fry reach maturity fairly quickly the longevity of Fundulus chrysotus is quite short. Because Fundulus chrysotus is lower in the trophic level and is a small fish, it primarily feeds on small and/or drifting organisms at, or near the surface of, vegetated areas. This particular topminnow is not currently listed as an endangered species, nor does it have any particular type of management plan. Although this may be the case, Fundulus chrysotus is still subject to, and affected by, negative, human induced influences. These influences should be examined closely so as to recommend proper management of the species.
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As stated above, the Golden Topminnow is geographically distributed throughout the southeastern portion of the continental U.S. Specifically, Fundulus chrysotus inhabits the Santee River Drainage of South Carolina west to the Trinity River Drainage of Texas. It can also be found throughout the Mississippi Embayment north to Kentucky, and Missouri. Further south Fundulus chrysotus inhabits the Lower Coastal Plain and is commonly scattered throughout Florida. [1] It has even been documented stretching its distribution northwest, extending into the Gulf Coastal Plain in McCurtain County Oklahoma and Mississippi County Missouri[2] Outside of these areas Fundulus chrysotus is extremely localized and uncommon.
Fundulus chrysotus’ diet ranges from aquatic plants to terrestrial invertebrates but consists mostly of aquatic invertebrates. (Etnier, 1993) Food habits were studied among many different species of fish throughout Lake Seminole, Florida-Georgia, including the food habits of the golden topminnow. Chrysotus was observed feeding on small proportions of Macrophytes (aquatic vegetation) and a much wider array of aquatic invertebrates, including Gastropoda (snails/slugs), large quantities of Ostracoda (seed shrimp), Ephemeroptera (mayflies), Coleoptera (water-beetles), and Chironomidae (non-biting midge flies). Although the Golden Topminnow’s diet does not include vertebrate prey, the most common food sources are seed shrimp and midge larvae with water beetles and mayflies as minor contributors to its diet. (Killgore, 1991) Because of its trophic level position, Fundulus chrysotus also has a wide array of predators that feed on smaller, surface feeding vertebrates. These include, but are not limited to the largemouth bass, Micropterus salmoides, the redear sunfish, Lepomis microlophus, the bluegill sunfish, Lepomis macrochirus, and the Bluespotted sunfish, Enneacanthus gloriosus. (Killgore, 1991)
Because Fundulus chrysotus is found inhabiting brackish water, it has an interesting tolerance to different salinity levels. When observed in 7 and 14 percent salinity, chrysotus has a 100 percent mean survival rate; where as at 21 percent salinity the rate decreases to 91 percent survival, at 28 percent salinity the mean survival rate decreases to 24 percent, and at 35 percent salinity the mean survival rate drops to 0 percent. (Peterson and Crego, 1997) The salinity tolerances described above account for Fundulus chrysotus’ native range throughout coastal waters and brackish waters, allowing for survival and reproduction in a narrow range of salinities. Negative human influences do not specifically harm this particular species, but many aquatic, vertebrate organisms. Some major influences include habitat pollution and the utilization of marsh lands and brackish waters by humans for agricultural purposes.
Fundulus chrysotus breeds throughout the spring and on into the summer months from April to July, and sometimes as late as September. During courtship the male swims in loops or circles above or beside the female, sometimes pausing to bob his head up and down. Eggs are released individually and deposited on the roots of floating plants or on other fibrous material by the female, where afterwards they are fertilized one at a time by the male. After hatching the larvae rest on leaves or on the bottom and begin to grow quickly reaching maturation after 10 months. (Ross et al, 2001) At maturation, Fundulus chrysotus becomes slender with a rounded caudal fin and a deep caudal peduncle. The mouth is small and slightly superior and the dorsal fin is set far back on the body and begins posterior to the anal fin origin. A lateral line is absent with 7-9 dorsal rays, 9-11 anal rays, 12-14 pectoral rays and 6 pelvic rays. During the breeding season, males develop prickly contact organs on the side of the body between the dorsal and anal fins, and on the ends of the last few dorsal rays, anal fin, and outermost rays of the pectoral fin. (Ross et al, 2001) The life expectancy of Fundulus chrysotus is around 2 years.
There is no current management plan specifically designed for Fundulus chrysotus due to the fact that it is not listed as an endangered or threatened species. Although this may be the case, there are precautions and recommendations that should be considered, not only for the species specific benefit of Fundulus chrysotus, but for the benefit of a healthy and biologically diverse habitat overall. As stated above, the current human induced influences that are negatively affecting the golden topminnow, and its predator and prey associates, are habitat pollution, specifically water pollution, and habitat destruction, in the form of agriculture. Because of the lack of pollution control and lack of monitoring, the habitat stability of the golden topminnow, and many other species of aquatics, is deteriorating. The issues of pollution are intensified when coupled with habitat destruction. This is mainly caused by humans utilizing the nutrient rich brackish and marsh water for agricultural purposes. Management recommendations include a much closer examination of the different affects of pollution levels. As for the habitat destruction due to agriculture, innovative and less harmful nutrient extraction plans should be outlined and examined and put into use so as to still provide nutrients and organics to produce and crops while causing the least amount of damage to those specific habitats..
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Etnier, David A., Wayne C. Starnes. 1993. The Fishes of Tennessee. 363-363
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Hunt, B. P. 1953. Food relationships between Florida Spotted Gar and other organisms in the Tamiami Canal, Dade County, Florida.Trans. Amer. Fish. Soc. 82(1952):13-33
Killgore, Jack K. 1991. Habitat Value of Aquatic Plants For Fishes. Environmental Laboratory Department of the Army Waterways Experiment Station, Corps of Engineers, 3909 Halls Ferry Road, Vicksburg, Mississippi 39180-6 and University of Maryland Center for Environmental and Estuarine Studies
Paul S. Wills, Robert J. Sheehan, Roy C. Heidinger, Brooks M. Burr & Miguel Nuevo Alarcóón. 1998. Range Expansion for the Golden Topminnow, Fundulus chrysotus (Güünther), and it Rediscovery in Missouri. Journal of Freshwater Ecology, 13:2, 253-254.
Peterson, Crego. 1997. Salinity Tolerance of Four Ecologically Distinct Species of Fundulus (Pisces: Fundulidae) From the Northern Gulf of Mexico. Marine Environmental Sciences Consortium of Alabama, pp. 45-49.
Secor, Stephen M,. 1987. The Golden Topminnow, Fundulus chrysotus (Cyrpinodontidae), an Addition to the Fish Fauna of Oklahoma. The Southwestern Naturalist 38:522-525.
Burr, Brooks M., Lawrence M. Page. 1991. A Field Guide to Freshwater Fishes: North America North of Mexico. 219-220.