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Rabbitsfoot (Theliderma cylindrica; listed originally as Quadrula cylindrica cylindrica)
Status: Threatened with Critical Habitat
September 17, 2013; Critical Habitat designated April 30, 2015
For questions regarding the Rabbitsfoot, please contact Chris Davidson at email@example.com or 501-513-4481.
The rabbitsfoot is a elongated, rectangular mussel that reaches 6 inches in length. It has a smooth, yellowish or greenish shell that becomes darker with age and a pattern of small dark green chevrons and triangles. The rabbitsfoot rarely burrows; instead it lies on it's side on the surface of the substrate
The rabbitsfoot has a reproductive strategy similar to that of other mussels: females release parasitic larvae (glochidia) that attach to the gills of specific species of host fish and later drop off as juvenile mussels. Rabbitsfoot mussels use multiple species of shiners (minnows) as host fish.
Rabbitsfoot generally inhabits small- to medium-sized stream and some larger rivers. It occurs shallow water areas along the bank and in shoals with reduced water velocity. Individuals have also been found in deep water runs (9-12 ft.). Primary substrate includes gravel and sand.
It has been estimated that the rabbitsfoot has been lost from approximately 64% of its historic range; only 11 populations rangewide are currently viable. It is currently found in 13 states.
Why is it Endangered?
The central reason for the decline of freshwater mussels is the modification and destruction of their habitat, especially from sedimentation, dams, and degraded water quality. The majority of the remaining viable rabbitsfoot populations live in waters considered "impaired" by the EPA or have multiple tributaries that are listed as impaired. The stressors on rabbitsfoot are expected to increase with increased water demand, further habitat degradation, and climate change. Since this species doesn't burrow like most other mussels, it is also more susceptible to displacement by fast-flowing water.
The rabbitsfoot is covered by the Upper Little Red River Safe Harbor Agreement (ULRR SHA) and the Saline, Ouachita, Caddo Safe Harbor Agreement (SOC SHA). These are voluntary agreements involving private or non-federal landowners whose actions help contribute to the recovery of this and other federally-listed species. Find out more about Safe Harbor Agreements.
Critical habitat is designated when there are geographic areas containing features we believe are essential to the conservation of a species. Designation of Critical Habitat does not affect land ownership or establish a refuge, reserve, preserve, or other conservation area. It does not affect activities on the land unless they are funded by federal dollars. Learn more about critical habitat here. You can read the final critical habitat designation in the Federal Register here.
The designation of critical habitat for the rabbitsfoot by the Service considers physical or biological features essential to the conservation of these species. These include, but are not limited to:
- Space for individual and population growth and for normal behavior;
- Food, water, air, light, minerals, or other nutritional or physiological requirements; and
- Sites for breeding, reproduction, or rearing; and
Primary constituent elements are those specific elements of the physical or biological features that provide for a species’ life history processes and are essential to the conservation of these species. Based on our current knowledge of the physical or biological features and habitat characteristics required to sustain life history processes for the rabbitsfoot, the primary constituent elements specific to these species are:
- Primary Constituent Element 1— Geomorphically stable river channels and banks (channels that maintain lateral dimensions, longitudinal profiles, and sinuosity patterns over time without an aggrading or degrading bed elevation) with habitats that support a diversity of freshwater mussel and native fish (such as, stable riffles, sometimes with runs, and mid–channel island habitats that provide flow refuges consisting of gravel and sand substrates with low to moderate amounts of fine sediment and attached filamentous algae).
- Primary Constituent Element 2— A hydrologic flow regime (the severity, frequency, duration, and seasonality of discharge over time) necessary to maintain benthic habitats where the species are found and to maintain connectivity of rivers with the floodplain, allowing the exchange of nutrients and sediment for maintenance of the mussel’s and fish host’s habitat, food availability, spawning habitat for native fishes, and the ability for newly transformed juveniles to settle and become established in their habitats.
- Primary Constituent Element 3— Water and sediment quality (including, but not limited to, conductivity, hardness, turbidity, temperature, pH, ammonia, heavy metals, and chemical constituents) necessary to sustain natural physiological processes for normal behavior, growth, and viability of all life stages.
- Primary Constituent Element 4— The presence and abundance (currently unknown) of fish hosts necessary for recruitment of the rabbitsfoot. The occurrence of natural fish assemblages, reflected by fish species richness, relative abundance, and community composition, for each inhabited river or creek will serve as an indication of appropriate presence and abundance of fish hosts until appropriate host fish can be identified.
- Primary Constituent Element 5— Either no competitive or predaceous invasive (nonnative) species, or such species in quantities low enough to have minimal effect on survival of freshwater mussels.
Range in Arkansas: