Proposal for Identifying potential threats to the Manitou Cave Snail (Antroribus breweri) through recharge area delineation using groundwater tracing
Summary
The Manitou Cave Snail (Antroribus breweri) is a monotypic, freshwater snail species that appeared in the Center for Biological Diversity’s 2010 petition to the U.S. Fish and Wildlife Service. The species is endemic to only Manitou Cave in northern Alabama near the city of Fort Payne. When a species is petitioned to be federally listed one of the first items to be examined is to identify what current and potential threats exist for the population. In many cases, especially with regards to aquatic species, these threats are identified based on the topographic drainage area where the critical habitat is located, identifying land uses which might be detrimental, and then working to mitigate or reduce those threats. In karst landscapes, [...]
Summary
The Manitou Cave Snail (Antroribus breweri) is a monotypic, freshwater snail species that appeared in the Center for Biological Diversity’s 2010 petition to the U.S. Fish and Wildlife Service. The species is endemic to only Manitou Cave in northern Alabama near the city of Fort Payne. When a species is petitioned to be
federally listed one of the first items to be examined is to identify what current and potential threats exist for the population. In many cases, especially with regards to aquatic species, these threats are identified based on the topographic drainage area where the critical habitat is located, identifying land uses which might be detrimental, and then working to mitigate or reduce those threats. In karst landscapes, the drainage area for a specific cave or spring is often not able to be identified (or delineated) without the use of groundwater tracing tests. In subterranean aquatic ecosystems the area which drains to a cave stream or spring is referred to as the recharge area and may drain areas geographically distant from the stream/spring through recharge features such as swallets, losing streams, and sinkholes. Water often enters the aquifer rapidly and without any filtration, creating a high potential for sedimentation and contamination of groundwater resources. Thus, in karst areas, when trying to identify threats to species of concern, for possible listing or de-listing, it is critical to delineate a recharge area for the stream/spring which serves as habitat.
Sensitive biota which inhabit these systems are vulnerable to surface activities which occur in the surrounding recharge area but may be geographically distant from the cave itself. Since many cave biota of the eastern United States are stygobionts with a high rate of endemism, maintaining a high degree of water quality is critical and knowing the recharge area which contributes flow to a karst system is the first step towards ensuring a healthy subterranean ecosystem.
Manitou Cave in northeastern Alabama is a 1.7 km-long stream cave located near the town of Fort Payne. The cave is the only known habitat for the Manitou Cave Snail, a stygobiont first found in 1939 and genotyped in 1990, which lives in the main stream that flows through the cave.
A study is proposed to delineate a recharge area for Manitou Cave in order to aid in assessing possible threats to the species. Currently the recharge area for the cave is completely unknown and due to the cave’s proximity to ongoing residential development and an active quarry operation, knowing the recharge area will identify which areas directly influence the water quality and quantity of the cave stream. Additionally, should the cave management and/or wildlife agencies choose to acquire land for preservation then the recharge area will provide a focus area for such efforts. The project is expected to last 6-8 months from the start of the project to the delivery of a recharge area map to the FWS. Applicability of the techniques utilized at Manitou Cave to evaluate recharge areas to other critical cave habitat in north Alabama, central and east Tennessee and northwest Georgia will be evaluated with USFWS and others to help prioritize future efforts in cave and karts regions.
Objectives:
1. Conduct a karst hydrologic inventory of the area surrounding Manitou Cave identifying major discharge (springs and streams) and recharge features (sinks and swallets) that will be monitored during the study or used as a dye injection location
2. Perform two rounds dye injections at four locations per round, monitoring at nearby discharge features and within Manitou Cave
3. Using the results of the dye tracing to identify the recharge area of Manitou Cave as well as define boundaries between the Manitou Cave recharge area and adjacent spring basins.
4. Use the delineated recharge area to identify threats to water quality, and thus Antroribus breweri, based on land use and/or local knowledge of features, industries, or other point sources.
5. Provide these tools to agency mangers to evaluate the potential listing or delisting of the petitioned Antroribus breweri based upon threat identification from the dye tracing study.
Work will pertain to identifying potential threats to a southeastern endemic aquatic cave snail, Antroribus breweri, by delineating a recharge area for the critical habitat.
