Overview
Fountain darters require undisturbed stream floor habitats, a mix of submergent plants, clear and clean water, invertebrates for food, constant water temperatures and adequate spring flows. The fountain darter is only found in the Comal and upper San Marcos rivers in Texas.
The fountain darter was listed as endangered on October 13, 1970 under the Endangered Species Conservation Act of 1969 and then under the Endangered Species Act of 1973. The primary threats to fountain darters are the quality and quantity of aquifer and spring water, including drought conditions and increased groundwater utilization resulting in reductions to or loss of spring flows. Habitat alternation is also a threat to the species, which can be caused by flooding, dams and recreation. Non-native species can threaten fountain darters though competition, habitat disturbance and parasitic infection. We work with our partners to ensure the springs and groundwater continue to provide clean and healthy freshwater to their microhabitats. We also collaborate with our partners to support the important life history of this species and conduct biological research to address its needs.
Scientific Name
Identification Numbers
Characteristics
Physical Characteristics
Adult fountain darters range in length from 0.75 to 1.5 inches.
The fountain darter is a small benthic, reddish-brown fish.
Life Cycle
Reproduction may occur year-round in areas of high-quality habitat in both the Comal and San Marcos systems, with a strong spring peak in reproduction - with limited reproduction in summer and fall of most years - in areas of lower quality habitat farther downstream.
Fountain darter eggs have been found attached to mosses and algae in Spring Lake and on filamentous algae Rhizoclonium sp., and native and non-native submergent plants, including Hygrophila polysperma, Hydrilla verticillata, Ludwigia repens, Sagittaria sp. and Texas wild-rice in the San Marcos River. Immediately after hatching, fry are not free swimming, in part due to the reduced size of their swim bladders.
Habitat
Fountain darters prefer undisturbed stream floor habitats and a mix of submergent plants like algae, mosses and vascular plants), in part for cover. This species also depends on clear and clean water, as well as an invertebrate food supply of living organisms like copepods, fly and mayfly larvae. Fountain darters also prefer constant water temperatures within the natural and normal river gradients and adequate springflows. Fountain darter densities are lower in areas lacking vegetation.
A natural body of running water.
Geography
The fountain darter occupies virtually all of the Comal River and most of the San Marcos River above the confluence of the San Marcos River and Blanco River. In the San Marcos River, fountain darter densities appear to be highest in the upper segments of the river and decrease markedly in an area below Cape's Dam.
The fountain darter population was extirpated from the Comal River system in the mid-1950s. The primary cause of extirpation is thought to be the 1949 to 1956 drought of record, when Comal Springs stopped flowing for 144 days from June to November, 1956. The Comal River was repopulated with fountain darters from the San Marcos River in 1975 and 1976. Fountain darters now occupy Comal Springs and the Comal River from Landa Lake downstream to the confluence with the Guadalupe River.
Timeline
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