[Federal Register: August 14, 2002 (Volume 67, Number 157)]
[Rules and Regulations]               
[Page 52879-52889]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]



Fish and Wildlife Service

50 CFR Part 17

RIN 1018-AI19

Endangered and Threatened Wildlife and Plants; Determination of 
Endangered Status for the Tumbling Creek Cavesnail

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Final rule.


SUMMARY: We, the Fish and Wildlife Service (Service), determine the 
Tumbling Creek cavesnail (Antrobia culveri) to be an endangered species 
under the Endangered Species Act of 1973, as amended (Act). This 
species is known to occur in one cave in Missouri. The distribution of 
this species in Tumbling Creek has decreased by 90 percent since 1974. 
Although cavesnail numbers fluctuated seasonally and annually between 
1996 and 2000, the species was not found in the monitored section of 
the cave stream during six surveys in 2001 and two surveys in 2002. 
Small numbers of individuals continue to exist in other portions of the 
cave stream. Because the sudden population decline demonstrates a 
significant and imminent risk to the well-being of the Tumbling Creek 
cavesnail, we find that listing this species is necessary to provide 
Federal protection pursuant to the Act.

DATES: This final rule is effective August 14, 2002.

ADDRESSES: The complete file for this rule is available for inspection, 
by appointment, during normal business hours at the U.S. Fish and 
Wildlife Service, Columbia Field Office, 608 E. Cherry St., Room 200, 
Columbia, MO 65201-7712.

FOR FURTHER INFORMATION CONTACT: Paul McKenzie, Ph.D., Columbia Field 
Office (see ADDRESSES) (telephone: 573-876-1911, ext. 107; e-mail: 
paul_mckenzie@fws.gov; facsimile: 573-876-1914). Individuals who are 
hearing-impaired or speech-impaired may call the Federal Relay Service 
at 1-800-877-8337 for TTY assistance.



    The Tumbling Creek cavesnail (Antrobia culveri) was described as a 
new species by Hubricht (1971) from specimens taken by David Culver, 
Thomas Aley, and Leslie Hubricht in 1969 and 1970. Antrobia culveri is 
the type species for the genus Antrobia, also described new to science 
in 1971 by Hubricht. Hershler and Hubricht (1988) examined specimens of 
A. culveri and confirmed the taxonomic placement of this species in the 
subfamily Littoridininae of the Gastropod family Hydrobiidae. They also 
noted the similarity of the genus Antrobia to, but distinguished it 
from, the genus Fontigens, which contains cave-adapted snails found in 
other caves and springs of the Ozark Plateau in Missouri and Arkansas. 
The Tumbling Creek cavesnail is a small, white, blind, aquatic snail. 
Hubricht (1971) provided the following measurements of the type 
specimen: height 2.3 millimeters (mm) (0.09 inches (in)); diameter 2.0 
mm (0.08 in); aperture height 1.2 mm (0.05 in); aperture diameter 1.1 
mm (0.04 in); with a small, conical, well-rounded, pale-yellow shell 
containing about 3.5 whorls (Hubricht 1971). The Tumbling Creek 
cavesnail is restricted to a single cave stream in Tumbling Creek Cave 
in Taney County, southwestern Missouri.
    Greenlee (1974) provided the first information on the habitat of 
the species. He reported that the species was found primarily on ``3 
inch gravel substrate'' (presumably meaning small stones or cobble of 
3-inch (7.5 cm) diameter), with a few individuals observed using the 
recesses of a solid rock stream bottom. Greenlee's use of a Surber 
Sampler, however, may have biased his survey to search for rocks 
smaller than 25 cm (10 in) in diameter (Julian J. Lewis, J. Lewis & 
Associates, Clarksville, IN; in litt., January 27, 2002). Greenlee 
(1974) did not note whether the snails used the upper or lower surface 
of the 3-inch gravel he observed them on, or whether the species was 
ever observed using larger rocks within the cave stream. Subsequent 
surveyors, however, have failed to document A. culveri using a solid 
rock bottom, and the species is usually observed on the undersurface of 
rocks and gravel of various sizes (Ashley unpub. data; McKenzie in 
litt., September 16, 1996; Ashley and McKenzie, pers. obs.). Although 
Greenlee (1974) stated that the Tumbling Creek cavesnail was absent 
from areas of the stream that contained bat guano, subsequent observers 
(Ashley 2001a; Ashley and McKenzie, pers. obs.) have noted A. culveri 
in portions of

[[Page 52880]]

Tumbling Creek where bat guano occurs. Greenlee (1974) noted that the 
species appears to prefer areas of the stream that lack silt, but 
Ashley (2000) found no significant differences in snail populations 
between habitats having silt and those lacking silt. There is 
insufficient data currently available to determine if silt is 
detrimental to the Tumbling Creek cavesnail. Tom and Cathy Aley 
suggested (pers. comm., August 30, 2001) that silt deposition in recent 
years in the stream has ``cemented'' smaller rocks to the stream bottom 
making their undersurface unavailable to cavesnails. This hypothesis is 
supported by observations made by researchers while conducting 
cavesnail surveys (e.g., Ashley and McKenzie, pers. obs.).
    Although little is known regarding the biology of this cavesnail, 
Greenlee (1974) postulated that the species feeds on aquatic 
microfauna. Because Tumbling Creek cavesnails have been concentrated in 
sections of Tumbling Creek Cave that are usually adjacent to large 
deposits of bat guano, it has been postulated that Antrobia culveri is 
indirectly dependent upon these deposits for food (Greenlee 1974). 
Other life history aspects of this species, including its reproductive 
behavior, are unknown. Although nothing is known about the longevity or 
movements of this species, some limited information is available on the 
frequency of shell sizes within the population across different 
seasons. Ashley (2000) examined shell length data collected between 
1996 and 2000 and noted that the average length of A. culveri shells 
exhibited a slight peak during summer months but further noted that the 
difference was not statistically significant. Ashley (2000) also 
analyzed the frequency distribution of cavesnail shell lengths from 
fall data collected between 1997 and 2000 and noted a decrease in the 
frequency of smaller shells over that period. Ashley (2000) concluded 
that both fewer snails and fewer smaller snails in the younger age 
classes were observed in the more recent fall visits conducted from 
1997 through 2000. This suggests that there has been a reduction in 
recruitment of younger age classes into the population between 1997 and 
    The fauna of Tumbling Creek Cave is highly diverse (Thomas Aley, 
Ozark Underground Laboratory (OUL), in litt. 1978; Cecil Andrus, USDI, 
in litt. 1980). In addition to one species included in the Missouri 
Department of Conservation's (MDC) Checklist of Species of Conservation 
Concern (Missouri Natural Heritage Program 2001) (i.e., a cave 
millipede (Scoterpes dendropus)), Antrobia culveri is associated with 
at least three, and possibly as many as six, species that are new to 
science but have not yet been formally described: a millipede 
(Chaetaspis sp.), a terrestrial isopod (Caucasonethes sp.), an amphipod 
(Stygobromus sp.), a dipluran (Plusiocampa sp.), a phalangodid 
harvestman (Phalangium sp.), and a cave spider (Islandiana sp.). 
Tumbling Creek Cave also provides habitat for a large maternity colony 
of federally listed gray bats (Myotis grisescens), with a recent 
estimated breeding population of 12,400 in 1998 (Dr. William Elliott, 
MDC, in litt. October 9, 2001). Historically, the gray bat breeding 
population included an estimated 50,000 individuals (MDC 1992, Missouri 
Natural Heritage Program 2000). The Gray Bat Recovery Plan lists 
Tumbling Creek Cave as a ``Priority 1'' cave. Priority 1 gray bat caves 
have the highest level of biological significance for a gray bat 
maternity site (i.e., a cave deemed to be ``absolutely essential'' in 
preventing the extinction of the endangered gray bat) (U.S. Fish and 
Wildlife Service 1982). There have also been historical observations of 
a very small hibernating population of the federally listed Indiana bat 
(Myotis sodalis). However, the Indiana bat has not been documented at 
the site since 1989 (Missouri Natural Heritage Program 2000).
    Tumbling Creek Cave is owned by Tom and Cathy Aley of Protem, MO. 
Because of its rich cave fauna, the large maternity colony for the 
endangered gray bat, and its diverse physical features, Tumbling Creek 
Cave was designated as a National Natural Landmark and approved for 
inclusion on the National Registry of Natural Landmarks under the 
authority of the Historic Sites Act of 1935 (49 Stat. 666; 16 U.S.C. 
461 et seq.) (Cecil Andrus, USDI, in litt., 1980; 48 FR 8693). Tumbling 
Creek Cave and approximately 395 acres surrounding the cave were 
embodied in the designation, including about 140 surface acres owned by 
the Aleys and about 255 surface acres owned by two adjacent property 

Status and Distribution

    Antrobia culveri is known only from Tumbling Creek Cave in Taney 
County, southwestern Missouri. In an extensive survey of publicly and 
privately owned Missouri caves, no additional populations of this 
cavesnail were discovered (Gardner 1986). Recent surveys conducted in 
nearby caves and springs by Dr. David Ashley of Missouri Western State 
College, St. Joseph, MO, have also failed to locate this species at any 
other sites (David Ashley, in litt. November 2001). The fact that no 
additional populations were found in springs in close proximity to 
Tumbling Creek Cave supports the long-held contention that Tumbling 
Creek cave is the only location where this species occurs.
    Antrobia culveri was historically known from an estimated area of 
1,016 square meters (m2) (10,900 square feet 
(ft2) or 0.25 acres) of Tumbling Creek along approximately 
229 meters (m) (750 feet (ft)) of the stream in the middle one-third of 
the lower stream passage in Tumbling Creek Cave (Greenlee 1974). Based 
on a survey of approximately 630 m2 (6,800 ft2) 
of suitable habitat within the 457 m (1,500 ft) of human-accessible 
cave-stream habitat, Greenlee (1974) estimated the population of 
Tumbling Creek cavesnails at 15,118 individuals.
    In 1995, we reviewed the status of the species, including the 
survey methodology originally established by Greenlee (1974), and 
determined that an inadequate description of the survey methods made it 
difficult to determine the number of plots taken. Our lack of knowledge 
on the number of plots sampled by Greenlee made it difficult to 
interpret his population estimates and impossible to duplicate his 
survey methods. Therefore, we concluded that a new and more rigorous 
statistical survey design would be necessary to establish population 
trends for the species. Following meetings with Dr. Pam Haverland of 
the U.S. Geological Survey, Columbia Environmental Research Center in 
Columbia, MO, and Mr. Tom Aley, President of Ozark Underground 
Laboratory (OUL) and owner of Tumbling Creek Cave, a sampling protocol 
was established within an approximate 75 m (247 ft) section of Tumbling 
Creek that was known to be inhabited by Antrobia culveri but that would 
minimize any potential impacts to the federally endangered gray and 
Indiana bats.
    Following the establishment of sampling stations within Tumbling 
Creek Cave, and an initial September 1996 survey using those stations 
(McKenzie, in litt. 1996), we contracted Dr. David Ashley, of Missouri 
Western State College, St. Joseph, MO, to monitor population trends of 
the Tumbling Creek cavesnail. Ashley completed 19 separate monitoring 
trips between September 3, 1997, and March 23, 2002 (Ashley 2000, 
2001a, 2001b, 2001c, 2002). Ashley (2000, 2001a, 2001b, 2001c, 2002) 
determined that population estimates of Antrobia culveri within the 
monitoring stations fluctuated both seasonally and annually, and ranged 
from a high of 1,166

[[Page 52881]]

individuals on September 3, 1997, to a low of 0 individuals on January 
11, March 17, May 8, July 16, August 31, and November 2, 2001, and 
January 9 and March 23, 2002. Ashley concluded that a significant 
decrease in the numbers of cavesnails had occurred between September 9, 
1996, and March 23, 2002 (Ashley 2002).
    Although the 2001 and 2002 surveys failed to document the presence 
of any cavesnails within the established monitoring stations, 40 
individuals were discovered upstream of the sampling stations in March 
2001. During March 16-18, 2001, Ashley and others surveyed the entire 
human-accessible 457 m (1,500 ft) of Tumbling Creek, including a small 
tributary that has approximately 9 additional meters (30 ft) of 
accessible habitat. A total of 39 person-hours was expended in 
searching a total of 1,054 rocks in the 466 m (1,530 ft) of available 
habitat. A total of 39 cavesnails were located in a 14-m (45-ft) 
section of the stream upstream from the monitoring stations, and 
another cavesnail was found in the tributary (Ashley 2001a). Subsequent 
surveys in May, July, September, and November, 2001, and January, 2002, 
documented the presence of cavesnails only in this 14-m section 
upstream of the established sampling stations. The small tributary 
stream was not searched during those subsequent surveys. A more 
thorough search was not conducted in either the tributary or the area 
upstream from the sampling stations in order to minimize disturbance to 
cavesnails in those areas. Observations made between September 1997 and 
March 2002 suggest that the numbers of Antrobia culveri have declined 
significantly from estimates obtained by Greenlee (1974); however, 
differing sampling methods make it impossible to directly compare 
Ashley's estimates with those of Greenlee.
    In addition to Greenlee's 1974 survey and the standardized surveys 
conducted between 1996 and 2002, other attempts have been made to 
monitor the species' status and derive estimates of its abundance. A 
June 1991 survey conducted by Tom Aley, Paul McKenzie (Service, 
Columbia, MO), and Dennis Figg (MDC, Jefferson City, MO) located 42 
individuals after a 9 person-hour search (McKenzie, pers. obs.). A June 
1993 survey conducted by Monty Holder (a high school biology 
instructor) of Sedalia, MO, and three assistants located 21 individuals 
during 6 person-hours of search effort (Tom Aley, in litt. 1993), but 
the number of plots sampled is unknown. On August 29, 1995, Paul 
McKenzie and Cathy Aley searched for the species and attempted to 
estimate the number of cavesnails discovered per 0.3 m2 (1 
ft2) plot. This survey yielded 6 cavesnails in 22 plots or 
0.27 cavesnails per plot (McKenzie, unpubl. data). This compares to an 
estimated 2.16 cavesnails per plot observed by Greenlee (1974) when 
equivalent plot sizes were calculated for analysis purposes. Although 
it is impossible to determine the exact number of plots sampled by 
Greenlee (1974), he did record the average number of snails per plot, 
and this can be compared to the same variable measured in 1995. A 
decrease from 2.16 cavesnails per plot to 0.27 cavesnails per plot 
would represent an approximate 88 percent decrease in the species' 
density over the 22-year period between 1974 and 1995.

Previous Federal Action

    On January 6, 1989, the Service published an Animal Notice of 
Review (54 FR 54554-54579) which included the Tumbling Creek cavesnail 
as a category 2 candidate species for possible future listing as 
threatened or endangered. Category 2 candidates were those taxa for 
which information contained in the Service's files indicated that 
listing may be appropriate but for which additional data were needed to 
support a listing proposal. On November 21, 1991, the Service published 
an Animal Candidate Notice of Review (56 FR 58804-58836), which 
elevated the Tumbling Creek cavesnail to category 1 status. Category 1 
candidates were those taxa for which the Service had on file sufficient 
information on biological vulnerability and threats to support 
preparation of listing proposals. In the subsequent February 28, 1996, 
Candidate Notice of Review (61 FR 7596-7613), we indicated that the 
category 2 candidate species list was being discontinued, and that 
henceforth the term ``candidate species'' would be applied only to 
those taxa that would have earlier fit the definition of the former 
category 1 candidate taxa, that is, those species for which we had on 
hand sufficient information to support a listing proposal. Antrobia 
culveri was retained as a candidate species in that notice.
    In 1996, we initiated a 5-year set of standardized surveys designed 
to better assess and quantify the decline in the species' population 
that was apparent from the earlier data. In January 2001, Ashley (pers. 
comm. January 14, 2001) notified the Service that no cavesnails were 
observed within the established monitoring stations during the January 
11 survey. He further reported that an analysis of 5 years of data 
collected between September 1996 and March 2001 indicated that the 
population of the species had exhibited an alarming decline (Ashley 
2001b). Based on this information, the Service determined that it was 
necessary to more closely monitor the species by having surveys 
conducted once every two months. Surveys conducted every two months 
between March 2001 and March 2002 have yielded the same results--no 
cavesnails have been found within the established sampling section of 
Tumbling Creek (Ashley 2002).
    Recognizing the need for prompt additional conservation actions for 
the species, on January 30, 2001, Region 3 of the Service recommended 
changing the listing priority number for the Tumbling Creek cavesnail 
from 7 to 1 based upon the mid-January monitoring that failed to locate 
any cavesnails (Service 2001). Region 3 also recommended pursuing an 
emergency listing of the species and simultaneously publishing a 
proposal for long-term listing as endangered under the Act as soon as 
funding became available. On October 30, 2001, we published an updated 
Candidate Species Notice of Review (66 FR 54808) that formally changed 
the listing priority number for Antrobia culveri from 7 to 1, 
reflecting our increased concern for the survival of the species.
    On August 29, 2001, the U.S. Department of the Interior reached an 
agreement with several conservation organizations regarding a number of 
listing actions that had been delayed by court-ordered critical habitat 
designations and listing actions for other species. That agreement was 
subsequently approved by the U.S. District Court for the District of 
Columbia. Under the agreement, the Service and the organizations agreed 
to significantly extend the existing court-approved deadlines for the 
actions on the other species, thereby making funds available for a 
number of listing actions judged to be higher priority by the Service. 
Those higher priority listing actions included the emergency listing of 
the Tumbling Creek cavesnail.
    On December 27, 2001 (66 FR 66803), we listed Antrobia culveri on 
an emergency basis for 240 days through August 26, 2002. On the same 
date (66 FR 66868), we published a proposal to list the Tumbling Creek 
cavesnail as an endangered species under the standard listing 
provisions of the Act, and solicited comments on the proposed rule. The 
comment period was opened for 60 days and closed February 25, 2002.

[[Page 52882]]

Summary of Peer Review and Public Comments

    In the December 27, 2001, proposed rule, we requested all 
interested parties to submit factual reports or information that might 
contribute to the development of a final rule. We also provided a 
notice indicating that a request for a public hearing could be made by 
February 11, 2002. We contacted appropriate Federal and State agencies, 
county governments, scientific organizations, and interested parties 
and requested their comments. We published notices inviting public 
comment in the Springfield, MO, News Leader and the Branson, MO, Tri-
Lakes Daily News. In accordance with our July 1, 1994, Interagency 
Policy on Peer Review (59 FR 34270), we requested the expert opinions 
of independent specialists regarding pertinent scientific or commercial 
data and assumptions relating to the supportive biological and 
ecological information in the proposed rule. The purpose of such review 
is to ensure that the listing decision is based on scientifically sound 
data, assumptions, and analyses, including input of appropriate experts 
and specialists.
    We requested scientific peer review of our proposed endangered 
listing from four invertebrate zoologists who possess expertise on the 
cavesnail or other invertebrates, and also solicited comments from one 
research fisheries biologist who has expertise on the potential impacts 
of contaminants on aquatic invertebrates. We received a written 
response and comments from all five of these experts; we also received 
comments from five private land owners within the recharge area for 
Tumbling Creek Cave during the open comment period. No requests for a 
public hearing were received. All species experts and private 
landowners strongly supported the listing proposal and agreed that this 
species is in need of Federal protection as an endangered species. Four 
of the five peer reviewers commented that the data on changes in 
cavesnail numbers were very thorough and that there was clear 
scientific evidence for listing the species as endangered. The fifth 
peer reviewer did not comment on adequacy of the data.

A. Technical and Editorial Comments

    Several technical and editorial comments and corrections were 
provided by two peer reviewers. Clarification of biological 
terminology, enhanced explanations of information cited from several 
references, and the inclusion of additional literature citations to 
strengthen Factors A through D, discussed below, were recommended. We 
have incorporated the majority of the recommended changes, as 
appropriate. In a few cases, suggested changes were not made if we 
determined that incorporating the change in text would not improve the 
clarity of the discussion.

B. Suggestions Related to Recovery Actions

    Three peer reviewers and two private land owners suggested various 
recovery actions that could benefit the cavesnail or its habitat. We 
will prepare a recovery plan for the cavesnail following the 
publication of the final rule, and these comments will be considered 
for incorporation into the recovery plan at that time. They are not 
discussed in this document, because they are not germane to this 
listing decision.

C. Specific Comments

    All peer reviewers commented on the possible reasons for the recent 
decline in cavesnail numbers. With the exception of the introduction of 
a few new suggestions discussed below, most of the reasons provided by 
the peer reviewers are identical to those outlined in the December 27, 
2001, emergency rule. All peer reviewers reaffirmed the supposition 
that siltation from erosion problems, overgrazing, poor land 
management, deforestation, or the sudden appearance and population 
explosion of limpets probably contributed to the decline in the 
species. Other reasons presented by peer reviewers that were previously 
provided in the Service's emergency rule were: eutrophication or 
nutrient runoff from livestock operations within the recharge area; 
disease; depressed dissolved oxygen levels; and degraded water quality 
from various waterborne contaminants. Two private landowners also 
believed that silt deposited into Tumbling Creek cave was a major 
contributor to habitat loss of the species. Newly suggested reasons 
given by peer reviewers for the decline in cavesnail numbers that were 
not addressed in the emergency rule were: residual toxins in the 
surrounding substrate that could adversely affect the water quality of 
the cave stream and cause changes in water chemistry (e.g., change in 
pH or imbalances in the anion/cation exchange).
    Four of the five private landowners who provided comments stated 
their belief that the listing of Tumbling Creek cavesnail as an 
endangered species would not impact their property rights. The fifth 
landowner did not comment on this issue. Two respondents indicated that 
the declining population of Antrobia culveri served as a barometer on 
the quality of water important to area land owners and further noted 
that listing the species was important in preserving the rich 
biological diversity of the Ozarks on esthetic and ecological grounds. 
One peer reviewer and two land owners recommended that the entire 
recharge area of Tumbling Creek cave be designated as critical habitat. 
Comments related to the issue of critical habitat for this species are 
addressed below.

Summary of Factors Affecting the Species

    After a thorough review and consideration of all information 
available, we determine that the Tumbling Creek cavesnail should be 
classified as an endangered species. We followed procedures found in 
section 4 of the Act (16 U.S.C. 1533) and regulations (50 CFR part 424) 
promulgated to implement the listing provisions of the Act. We may 
determine a species to be endangered or threatened due to one or more 
of the five factors described in section 4(a)(1) of the Act. These 
factors and their application to the Tumbling Creek cavesnail (Antrobia 
culveri) are as follows:

A. The Present or Threatened Destruction, Modification, or Curtailment 
of Its Habitat or Range

    Antrobia culveri has exhibited a large decline in numbers since the 
first estimate was made by Greenlee (1974) (see Status and 
Distribution, above). Systematic sampling within various sections of 
Tumbling Creek was initiated in 1996 (McKenzie in litt. 1996). 
Placement of sampling quadrats was done by inspecting the area within 
each of the sampling sections and arbitrarily placing the sampling 
squares approximately equidistant along each section. Ashley reported a 
statistically significant decline in the snail population over the 
period between 1996 and the first quarter of 2002 (Ashley 2001c, 2002). 
Additionally, no cavesnails have been located at established monitoring 
stations during the last eight surveys (Ashley 2001a, 2001b, 2001c, 
    We also have documented a large reduction in the portion of the 
cave stream occupied by the cavesnail. Antrobia culveri was 
historically known from an estimated 229 m (750 ft) of Tumbling Creek 
(Greenlee 1974). The 229 m of occupied habitat in 1974 constituted 50 
percent of the 457 m (1,500 ft) of human-accessible cave-stream habitat 
that is believed to be

[[Page 52883]]

suitable for the cavesnail. The entire accessible 457 m (1,500 ft) of 
Tumbling Creek, including a small tributary that has approximately 9 
additional meters (30 ft) of accessible suitable habitat, was surveyed 
in March 2001. Cavesnails were found solely in one small (14-m) (45-ft) 
section of the stream and in the small tributary (Ashley 2001a). 
Observations between March and August 2001 suggest that A. culveri is 
now restricted to 23 m of available stream habitat or approximately 5 
percent of the 457 m of accessible suitable habitat. These figures 
indicate that distribution of this species in Tumbling Creek Cave has 
decreased by 90 percent.
    Species such as the Tumbling Creek cavesnail, which spend all of 
their life cycle in subterranean waters, are highly vulnerable to 
changes in the quality and quantity of that water. In turn, the quality 
and quantity of the subsurface water is highly dependent upon 
conditions and human activities on the land surface. Water feeds into 
losing streams and sinkholes that drain into underground karst 
conduits. Surface water moves into the subsurface system by a number of 
mechanisms, including sinkholes, percolation through sandy or gravelly 
soils and stream bottoms, and seepage and flowage into crevices. As 
water moves from the surface to the subsurface system, it carries the 
chemicals and particulate matter from the surface (Gines and Gines 
1992). The land surface that feeds water into a particular cave stream 
is referred to as the ``recharge area'' for that cave stream. Because 
recharge areas may be large and may consist of all or parts of several 
surface watersheds, it is critically important to accurately determine 
the boundaries of the recharge area with reliable hydrogeological 
methods. Only when the recharge area is accurately delineated can water 
quality threats be successfully addressed (Aley and Aley 1991).
    The recharge area that feeds water into Tumbling Creek Cave has 
been recently delineated by the cave owner, Mr. Thomas Aley of the OUL, 
who is also a recognized cave specialist and expert karst 
hydrogeologist (Aley and Aley 2001). Pending the results of additional 
recharge delineation studies currently being conducted by Aley on a 
tract of land recently purchased by him and Cathy Aley (Tom Aley, pers. 
comm., September 24, 2001), he estimated the recharge area to be 
approximately 2,349 hectares (5,804 acres or 9.07 square miles). Land 
ownership based on current data within the recharge area is: (1) Tom 
and Cathy Aley own approximately 1,550 acres, or 25 percent of the 
total; (2) employees of Ozark Underground Laboratory and other private 
individuals, who manage their property to protect water quality and 
benefit the species, own approximately 1,268 acres or 22 percent; (3) 
an estimated 1,300 acres or 23 percent is within Mark Twain National 
Forest; (4) the U.S. Army Corps of Engineers (CE) owns an estimated 100 
acres or 2 percent; and (5) other private landowners, whose land use 
practices and knowledge of the cavesnail are currently unknown to us, 
own approximately 1,636 acres or 28 percent. Thus, within the 
delineated recharge area for Tumbling Creek Cave, roughly 4,168 acres 
or approximately 72 percent is either in public or private ownership by 
entities who can be expected to manage their land to benefit the 
species. This includes 920 acres recently purchased by Tom and Cathy 
Aley, or about 22 percent of the total conservation ownership. However, 
most of this recently purchased land was subject to land use practices 
(e.g., over-grazing and removal of riparian vegetation) by the previous 
owner that resulted in heavy soil erosion that probably continues to 
contribute to deteriorating water quality in Tumbling Creek Cave. 
Remediation and restoration of these lands are planned and will require 
considerable funds, effort, and time.
    The Tumbling Creek cavesnail is likely threatened by habitat 
degradation through diminished water quality from upstream locations 
within the unprotected or improperly managed areas within the cave's 
delineated recharge zone. The dramatic decrease in the population and 
area occupied by this species is probably attributable to degraded 
water quality from these sources. In recent years, there has been a 
noticeable increase in water turbidity in Tumbling Creek; the increased 
turbidity has probably had an adverse effect on the water quality in 
the cave's stream (Tom and Cathy Aley, pers. comm., August 30, 2001). 
Increased silt loads within Tumbling Creek could adversely affect the 
cavesnail by hampering reproduction and recruitment by suffocating 
juvenile cavesnails (Ashley 2000). Several authors (e.g., Poulson 1996, 
Elliott 2000, Taylor et al. 2000) have noted that high sediment loads 
usually have a negative impact on aquatic species. Tom and Cathy Aley 
have also observed that clay particles within deposited silt have 
settled between gravel and rocks and cemented them together and to the 
stream bottom (Tom and Cathy Aley, pers. comm., August 2001). Such 
cementing decreases habitat available to cavesnails, especially 
interstitial areas, because the species is generally restricted to the 
undersurface of gravel and rocks. Coineau and Boutin (1992) 
demonstrated that interstitial habitats are critically important to the 
dispersal capabilities of animals with limited movements. Comacho 
(1992) suggested that the size, porosity, and compaction of sediment 
grains (e.g., clay vs. sand) was a limiting factor in the availability 
of interstitial habitats to aquatic cave organisms. Interestingly, 
Ashley (2000) determined that some Tumbling Creek cavesnails use silt-
covered substrates. This is different from the observations made by 
Greenlee (1974) who noted that cavesnails were not observed in areas of 
the stream where fine silt was deposited. Ashley's observations may be 
due to a reduction in the amount of silt-free substrates preferred by 
cavesnails which could force the species to use less favorable 
habitats. Although silt has been a component of Tumbling Creek since 
Greenlee's initial survey in 1974, it has apparently increased since 
that date (Tom and Cathy Aley, pers. comm., August 2001).
    Silt could also be harmful to Antrobia culveri indirectly due to 
the interrelationship between various harmful bacteria or viruses and 
some sediment mediums. Taylor and Webb (2000) reported that the 
survival of some bacteria and viruses may increase when they become 
attached to the surface of silt and clay particles and organic matter. 
Additionally, they noted that such harmful bacteria as coliform and 
fecal coliform bacteria ``may persist and reach much higher 
concentrations in aquatic sediments (especially in the presence of 
organic nutrients) than in the water column.'' Consequently, an 
increase of silt into Tumbling Creek could exacerbate the potential 
problems from bacteria and viruses originating from livestock wastes 
entering Tumbling Creek. Additional research is needed to determine the 
degree of silt deposition within Tumbling Creek and if the deposition 
of silt into the cave is adversely impacting the species, especially 
smaller and younger individuals (Ashley 2000).
    Potential sources of silt within the cave's recharge area have been 
identified on the two tracts recently purchased by Tom and Cathy Aley, 
including an earthen dam that burst, as well as severely degraded and 
eroded pastureland due to overgrazing. In the latter case, soil erosion 
has been exacerbated in the last six years by the removal of nearly all 
vegetation by bulldozing equipment within the riparian corridors of all 

[[Page 52884]]

and intermittent streams on one of those parcels. Tree removal 
activities associated with pasture expansion have increased soil 
erosion and resulted in the subsequent movement of silt into the cave 
system (Aley, Ashley, and McKenzie, pers. obs.). Harvey (1980) 
concluded that ``accelerated erosion and sediment transport'' was a 
problem within drainage basins that have ``excessive slopes,'' and 
identified ``timber cutting and land clearing for raising livestock, 
extending urban sprawl, and highway building'' as potential sources of 
``accelerated erosion.'' In addition to these sources, the construction 
of fire lanes associated with controlled burning on Forest Service 
property within the recharge area may increase the threat of soil 
erosion with a resulting decrease in water quality in Tumbling Creek.
    Other factors within the recharge area of Tumbling Creek Cave that 
could contribute to the deterioration of the water quality of Tumbling 
Creek include: (1) Nutrient enrichment from livestock feedlots or from 
fertilizers used for crop production or pasture improvement within the 
recharge area that could reduce dissolved oxygen levels in Tumbling 
Creek or become toxic to aquatic organisms at high concentrations; (2) 
chemicals used for highway maintenance or from accidental spills; (3) 
contaminants from different types of trash or hazardous waste materials 
deposited into sinkholes, ravines, and depressions; and (4) 
contamination from hormones, antibiotics, disinfectants, or other 
chemicals found in human and livestock wastes (Koplin et al. 2002). 
Contaminants presumably from crop fertilizers were detected at levels 
high enough in cave streams within the Perryville Karst Region of 
southeastern Missouri to be detrimental to aquatic life (Vandike 1985; 
Burr et al. 2001). Contamination of groundwater has occurred due to 
spills associated with traffic accidents in the Mammoth Cave area of 
Kentucky (U.S. Department of Interior 1983; U.S. Fish and Wildlife 
Service 1988; Taylor et al. 2000). Because portions of Routes 160 and 
125 occur within the recharge area for Tumbling Creek Cave, accidental 
spills resulting from traffic accidents could potentially occur. Taylor 
and Webb (2000) summarized the deleterious effects of various inorganic 
ions on the distribution and abundance of different aquatic cave 
isopods and amphipods. Taylor et al. (2000) suggested that several 
parameters, including depressed oxygen levels, improper pH levels, and 
the presence of metals, pesticides, and harmful bacteria may all 
contribute to the persistence or decline of aquatic cave organisms. 
Burr et al. (2001) reported that ``no less than one-half of sinkholes 
in Perry County, MO, contain anthropomorphic refuse, ranging from 
household cleansers and sewage to used pesticide and herbicide 
containers.'' Some unidentified point source pollution that was 
apparently dumped accidentally into Running Bull Cave in Perry County, 
MO, resulted in a mass mortality of cave-dwelling grotto sculpin (Burr 
et al. 2001). Eliott (2000) summarized the documented impact of various 
chemical pollutants into cave systems including sewage, contaminants 
from old batteries, nitric acid, leaks from petroleum products, brine 
pollution, herbicides, pesticides, solvents, fertilizers, milk, cream, 
tobacco waste products, and medical waste. Kolpin et al. (2002) sampled 
139 streams across 30 States, including Missouri, and documented the 
presence of human and livestock antibiotics, human prescription and 
nonprescription drugs, steroid compounds including several biogenic and 
synthetic reproductive compounds, and 30 different organic wastewater 
contaminants in 80 percent of the streams sampled. Although there are 
no waste water treatment facilities within the recharge area for 
Tumbling Creek cave, livestock antibiotics, hormones, and chemical 
treatments for controlling insect pests could originate from livestock 
facilities that occur within the cave's recharge area. The extent to 
which any of these factors have contributed to the decline of the 
Tumbling Creek cavesnail remains to be determined. Refer to Factor E 
for further discussion of these potential threats.

B. Overutilization for Commercial, Recreational, Scientific, or 
Educational Purposes

    Because access to Tumbling Creek Cave is controlled by the cave 
owners, all collection of and research on Antrobia culveri is strictly 
controlled. Consequently, there is no evidence, and very little 
likelihood, of overutilization of this species for commercial, 
recreational, scientific, or educational purposes. There is also no 
evidence that disturbance associated with conducting regular surveys is 
adversely affecting the species. Rocks that are examined for cavesnails 
are carefully replaced in the location from which they were removed, 
any specimens discovered are disturbed as little as possible and kept 
moist to reduce stress, and only a small percentage of the available 
habitat is sampled during each survey.

C. Disease or Predation

    The direct effect of disease on the Tumbling Creek cavesnail is not 
known and such risks to the species have not been determined. Because 
the Tumbling Creek cavesnail is known to inhabit only a single 
location, disease must be considered a potential significant threat to 
the survival of the species. Certain species of salamanders have been 
shown to be adversely impacted by the bacterium Acinetobacter that 
flourished due to increasing levels of nitrogen associated with the 
overstocking of livestock (Worthylake and Hovingh 1989). Similarly, 
Lefcort et al. (1997) and Kiesecker and Blaustein (1997) found that 
amphibians exposed to high levels of silt are susceptible to infection 
by different species of water mold of the genus Saprolegnia. 
Saprolegnia spp. are widespread in natural waters and commonly grow on 
dead organic material (Wise et al. 1995). Speer (1995) stated that some 
species of Saprolegnia are parasitic on aquatic invertebrates such as 
rotifers, nematodes, diatoms, and arthropods. High nitrogen and silt 
levels from overgrazing or other agricultural or urban runoff may 
increase the cavesnail's susceptibility to disease and may act 
synergistically with other risk factors (e.g., competition from 
limpets, discussed below) to jeopardize the survival of the remaining 
individuals. Whether the Tumbling Creek cavesnail is being adversely 
affected by bacteria or water molds associated with increased loads of 
nitrogen or silt into Tumbling Creek is unknown but warrants further 
    During the December 6, 1997, survey, a few individuals of an 
unknown species of limpet (Ferrissia sp.) were discovered for the first 
time on the same substrates used by Antrobia culveri within the 
established monitoring stations (Ashley, pers. comm., September 10, 
2001). Limpets were not observed again until the January 11, 2001, 
survey, after which their numbers began to increase. By the August 31, 
2001, survey, limpet numbers had increased explosively, and the 
presence of many small limpets, as well as larger limpets with visible, 
developing embryos, indicated that reproduction was taking place 
(Ashley, pers. comm., September 10, 2001; McKenzie pers. obs.) The 
reasons that caused these organisms to appear and increase in numbers 
within Tumbling Creek are unknown; it is also unknown whether they 
compete with the cavesnails for food, breeding substrates, or other 
necessary resources. Dr. Julian J. Lewis documented that the 
disappearance of

[[Page 52885]]

the rare isopod crustacean Caecidotea rotunda coincided with the 
appearance of limpets in a cave in southern Indiana (J. Lewis, in 
litt., January 27, 2002). Numerous investigations by David Culver and 
others (e.g., Culver 1970, 1975) have demonstrated that interspecific 
competition between aquatic cave invertebrates may reduce the 
availability of important niche habitats. Other cave invertebrates 
(e.g., a troglobitic isopod, Caecidota antricola.; a troglobitic 
amphipod, Stygobromus sp.; and a troglophilic amphipod, Gammarus sp.) 
coexist with A. culveri, often on the same rocks, but it is unknown if 
these species compete with the cavesnail in any way. Additional 
research is needed to determine if local environmental changes have 
provided a competitive advantage for one or more of these species over 
the Tumbling Creek cavesnail.

D. The Inadequacy of Existing Regulatory Mechanisms

    The primary cause of the decline of the Tumbling Creek cavesnail is 
unknown but is believed to be associated with factors within the 2,349-
hectare (5,804-acre) delineated recharge area that have adversely 
affected the water quality of Tumbling Creek. Federal, State, and local 
laws have not been sufficient to prevent past and ongoing impacts to 
areas within the cave's delineated recharge area. Antrobia culveri is 
listed as critically imperiled globally (G1) by The Nature Conservancy, 
as well as critically imperiled in the State (S1) on the Missouri 
Species of Conservation Concern Checklist (Missouri Natural Heritage 
Program 2001). The designation as G1/S1 on this checklist, however, 
provides no legal protection, but is simply utilized for planning and 
communication purposes (Missouri Natural Heritage Program 2001). 
Nonetheless, the species currently receives some protection under the 
Wildlife Code of Missouri (Wildlife Code) (Missouri Department of 
Conservation 2001) as a ``biological diversity element'' (Missouri 
Natural Heritage Program 2001). ``Biological diversity elements'' are 
protected under the following general prohibitions of chapter 4 of the 
Wildlife Code (3CSR10-4.110): ``(1) No bird, fish, amphibian, reptile, 
mammal or other form of wildlife, including their homes, dens, nests 
and eggs in Missouri shall be molested, pursued, taken, hunted, 
trapped, tagged, marked, enticed, poisoned, killed, transported, 
stored, served, bought, imported, exported or liberated to the wild in 
any manner, number, part, parcel or quantity, at any time, except as 
specifically permitted by these rules and any laws consistent with 
Article IV, sections 40-46 of the Constitution of Missouri. (2) Except 
as otherwise provided in this Code, wildlife may be taken only by 
holders of the prescribed permits and in accordance with prescribed 
methods. (3) No person, corporation, municipality, county, business or 
other public or private entity shall cause or allow any deleterious 
substance to be placed, run or drained into any of the waters of this 
State in quantities sufficient to injure, stupefy or kill fish or other 
wildlife which may inhabit such waters.''
    Under the Section 6 Cooperative Agreement between MDC and the 
Service, if a species is listed as endangered under the Act, the 
Conservation Commission of Missouri shall list the species as State 
endangered. The protection of all species in Missouri is outlined in 
Chapter 4 of the Wildlife Code, and regulations pertaining to 
endangered species are listed in section 3CSR10-4.111. Under the 
Wildlife Code, citizens can possess (but not sell or purchase) up to 
five individuals of any species without a permit and when not 
specifically protected elsewhere in the code (3CSR10-9.110). However, 
when a species is listed as endangered, citizens cannot possess any 
individuals and cannot import, transport, purchase, or take the species 
without a scientific collecting or special use permit. Although the 
term ``refuge'' is not defined under the Wildlife Code, there is also a 
provision that enables MDC's Director to establish refuges not to 
exceed 1 square mile for not more than 60 days to provide essential 
protection to endangered species. Furthermore, the Wildlife Code states 
that a species' ``home'' is protected. The term ``home'' is not defined 
in this statute and may provide limited or no protection for the 
cavesnail's habitat. For instance, the creek where the cavesnail 
resides and the cave's recharge area would probably not be considered a 
home and thus receive no protection under the Wildlife Code (Bob White, 
MDC, Protection Division Chief, pers. comm., October 2, 2001).
    The Federal Cave Resources Protection Act of 1988 (18 U.S.C. 4301-
4309; 102 Stat. 4546) was passed to ``secure, protect, and preserve 
significant caves on Federal lands'' and to ``foster increased 
cooperation and exchange of information between governmental 
authorities and those who utilize caves located on Federal lands for 
scientific, educational, or recreational purposes.'' Although this 
statute and a final rule to implement the Federal Cave Resources 
Protection Act on Forest Service land (59 FR 31152; June 17, 1994) 
provide protection for caves located on property owned by the Forest 
Service, they do not provide protection for caves whose recharge areas 
are within Forest Service boundaries if the caves themselves are under 
private lands, as is the case with Tumbling Creek Cave.
    Under Section 578.215 of the Missouri Cave Resources Act (Missouri 
Department of Conservation 2002), the following actions are prohibited: 
``A person shall not purposely introduce into any cave, cave system, 
sinkhole, or subsurface waters of the state any substance that will or 
could violate any provision of the Missouri clean water law as set 
forth in chapter 204, RSMo (Revised Statutes of Missouri), or any water 
quality standard or effluent limitation promulgated pursuant thereto.'' 
Although this statute is intended to prevent harmful chemicals from 
being placed into a cave, it is rarely enforced, and an individual 
prosecuted for a violation of this measure can be convicted of no more 
than a Class A misdemeanor; therefore, it is largely ineffective at 
providing protection for aquatic animals within a cave stream (Bill 
Elliott, Cave Biologist, Missouri Department of Conservation, Jefferson 
City, MO, pers. comm., March 15, 2002).
    The protection afforded Antrobia culveri from the statutes 
mentioned above is limited, does not provide adequate protections to 
its habitat, and includes no provisions to protect areas within the 
delineated recharge area for Tumbling Creek Cave. Therefore, we 
conclude the most likely threats to the species cannot be addressed by 
existing regulatory mechanisms.

E. Other Natural or Manmade Factors Affecting Its Continued Existence

    Several other potential factors, including point and non-point 
pollution, threats from residential and commercial development, and 
recent changes to the hydrological cycle within the 2,349-hectare 
(5,804-acre) delineated recharge area supporting Tumbling Creek Cave 
may have negative effects on the species. It is possible that the 
recent decline in cavesnail numbers is attributable to some yet to be 
identified point or non-point source pollution within the cave's 
recharge area. Because the Tumbling Creek cavesnail occupies a 
permanent, flowing stream, it will likely come in contact with any 
deleterious chemical or other material that enters the cave's recharge 
system. Silt deposition has been identified as a potential problem, 
especially to younger

[[Page 52886]]

cohorts of the cavesnail's population, but additional research is 
needed to determine if other contaminants are potentially involved. 
(See Factor A above.)
    Non-point source pollution may be a problem in a significant 
portion of the recharge area that feeds Tumbling Creek Cave. Potential 
sources of pollution include the drainage of barnyard and feedlot 
wastes and the discharge of treated sewage into sinkholes and losing 
streambeds within the cave's recharge area. The water quality of 
Tumbling Creek may also be threatened due to accidental spills into 
sinkholes or losing stream valleys feeding Tumbling Creek Cave from 
State and county highways passing through the recharge area. Such 
sources of pollution have been identified as potential problems for 
ground water in the Springfield-Salem Plateaus of southern Missouri 
(including the watershed that encompasses Tumbling Creek and its 
identified recharge zone) (Harvey 1980). The decline in numbers of the 
Tumbling Creek cavesnail may be due to one or several sources of 
pollution that have resulted in a deterioration of water quality within 
the recharge area for Tumbling Creek as outlined in Factor A. In 
comparing the quality of groundwater sites within the Ozark Plateaus 
(including southwestern Missouri) with other National Water-Quality 
Assessment Program (NAWQA) sites, Petersen et al. (1998) documented 
that: (1) Nitrate concentrations in parts of the Springfield Plateau 
aquifer were higher than in most other NAWQA drinking-water aquifers, 
and (2) volatile organic compounds were detected more frequently in 
drinking-water aquifers within the Ozark Plateaus than in most other 
drinking-water aquifers. Tumbling Creek Cave is within the NAWQA study 
boundaries; consequently, the cavesnail could be threatened from these 
contaminants. Peck (1998) concluded that all aquatic cave species were 
especially vulnerable to karst groundwater pollution. Elliott (2000) 
summarized numerous examples of cave systems being contaminated by a 
wide range of pollutants that are directly or indirectly dumped into 
cave streams and further suggested that reduced biotic diversity 
correlated with degraded water quality in three caves in Tennessee. 
Although no detailed water analyses have yet been performed on Tumbling 
Creek, an instrumentation package to measure water quality parameters 
will be installed in Tumbling Creek Cave during the summer of 2002.
    Aley (pers. comm., Jan. 19, 2001) postulated that the decline in 
cavesnail numbers may actually be because of too much gray bat guano 
that could deplete oxygen levels in Tumbling Creek, especially during 
periods of reduced flows as occurred during 1999-2001. Vandike (1982) 
and Elliott (2000) reported on a massive die-off of the Salem cave 
crayfish (Cambarus hubrichti) and the southern cavefish (Typhlichthys 
subterraneus) when a large quantity of liquid fertilizer containing 
ammonium nitrate and urea accidentally spilled into a losing stream and 
significantly lowered dissolved oxygen levels in Meramec Spring, which 
is 21 km (13 mi) downstream from the spill. What importance gray bat 
guano plays in the life history requirements of the Tumbling Creek 
cavesnail is yet to be tested experimentally. The instrumentation 
package mentioned above will provide data on dissolved oxygen levels 
once it is installed.
    Tumbling Creek Cave is approximately 45 km (28 mi) southeast of 
Branson, MO, which is one of the most rapidly expanding areas in the 
State due to tourism, outdoor recreation, and entertainment 
developments. If recent trends continue, it has been projected that the 
number of visitors attracted to this area would increase from an 
estimated level of 6 million in 1992 to 11 million by the year 2015. 
The accompanying growth in entertainment- and recreation-related 
activities will place even greater demands on this area of the State 
(Mullen and Keith 1992). Tumbling Creek Cave is about 4 km (2.5 mi) 
northwest of Bull Shoals Lake which is also undergoing additional real 
estate development. Consequently, it is likely that sections of the 
recharge zone for Tumbling Creek Cave will be adversely affected by 
real estate development and related construction and land management 
activities. Elliott (2000) provided multiple examples of how various 
land development activities have adversely impacted important karst 
resources in the eastern United States.
    Another potential threat to the species results from the close 
hydrologic association of Tumbling Creek with nearby Bull Shoals Lake. 
Occasional high water levels in this CE reservoir are believed to cause 
water to backup into the cave stream, threatening roosting bats and the 
cavesnail (Aley, pers. comm., July 16, 2000). The CE is considering 
raising the conservation pool of the reservoir by 10 feet, which will 
likely increase the frequency and duration of the backup events in 
Tumbling Creek Cave. Lewis (1994) reported that the habitat of the 
subterranean hydrobiid snail Antroselates spiralis in Mammoth Cave, KY, 
was reduced significantly due to ponding of the adjacent Green River by 
a dam downstream of the cave. The back-flooding created a siltation 
problem that fragmented previously occupied areas into disjunct islands 
of habitat (J. Lewis in litt., January 27, 2002).
    Climatic changes, especially recent periods of drought, may also be 
a contributing factor to the decline of the cavesnail. The National 
Oceanic and Atmospheric Administration's (NOAA) Palmer Drought Severity 
Index provides a widely recognized and accepted standard measurement of 
moisture conditions (NOAA 2001). The Index varies roughly from -6.0 
(extreme drought) to +6.0 (extremely wet), with -0.49 to 0.49 
indicating near normal conditions. Since the 1974 survey by Greenlee, 
there have been 4 periods in Southwest Missouri where the Index was 
below normal for 6 months or longer and was below an Index value of -
2.0 (moderate drought) for some part of that period. These events 
occurred in 2-year cycles: 1980-1981; 1991-1992; 1995-1996; and 1999-
2000. The 1980-1981 drought was the most prolonged and severe, with the 
Index reaching -5.0 (extreme drought). We further analyzed a 6-year 
period between 1995 and 2000, which is the approximate period that 
Ashley conducted his cavesnail monitoring. The Index was below normal 
for 6 months or more for 4 of these 6 years. The years, number of 
months the Index was below normal, and the averages for the negative 
indices are: 1995, 6 months, average Index -1.54; 1996, 7 months, 
average Index -1.2; 1999, 6 months, average Index -1.29; 2000, 10 
months, average Index -1.65. Preliminary data on NOAA's Web site 
indicate that below-normal moisture (negative Palmer Index) occurred in 
this region during the early part of 2001, but precipitation levels are 
now near normal.
    According to these climatic data, in 2 recent periods (1995-1996 
and 1999-2000) precipitation within the recharge area for Tumbling 
Creek Cave was below normal for an extended period. The direct or 
indirect impacts of these droughts on the cavesnail are unknown. 
Reduced flows in the cave stream, especially when combined with other 
threats, could hamper essential life history requirements (e.g., 
reproduction, food availability, water temperature); decrease the 
flushing of silt, guano, and harmful contaminants from the stream; and 
create an environment more favorable for competitors (e.g., limpets, 
isopods, and amphipods).

[[Page 52887]]

    The small population size and endemism (i.e., restricted to a 
single site) of Antrobia culveri makes it vulnerable to extinction due 
to genetic drift, inbreeding depression, and random or chance changes 
to the environment (Smith 1990) that can significantly impact cavesnail 
habitat. Inbreeding depression can result in death, decreased 
fertility, smaller body size, loss of vigor, reduced fitness, and 
various chromosome abnormalities (Smith 1990). Despite any evolutionary 
adaptations for rarity, habitat loss and degradation increase a 
species' vulnerability to extinction (Noss and Cooperrider 1994). 
Numerous authors (e.g., Noss and Cooperrider 1994, Thomas 1994) have 
indicated that the probability of extinction increases with decreasing 
habitat availability. Although changes in the environment may cause 
populations to fluctuate naturally, small and low-density populations 
are more likely to fluctuate below a minimum viable population (i.e., 
the minimum or threshold number of individuals needed in a population 
to persist in a viable state for a given interval; Gilpin and Soule 
1986, Shaffer 1981, Shaffer and Samson 1985). Current threats to the 
habitat of the Tumbling Creek cavesnail may exacerbate potential 
problems associated with its low population numbers and increase the 
chances of this species going extinct.


    Tumbling Creek cavesnail is known from a single cave in Taney 
County, southwestern Missouri. The distribution of this species has 
decreased in Tumbling Creek by 90 percent since 1974. Analysis of 
survey data collected at established sampling points between September 
9, 1996, and March 23, 2002, indicates that numbers of the species have 
decreased significantly, and the cavesnail is vulnerable to extinction. 
This decline has continued to the point that cavesnails are no longer 
present in portions of Tumbling Creek where they had always been found 
prior to 2001 using the same monitoring methodology. The Tumbling Creek 
cavesnail is likely threatened by habitat degradation through 
diminished water quality from upstream locations within the unprotected 
or improperly managed areas within the cave's delineated recharge zone. 
The dramatic decrease in the population and area occupied by this 
species is probably attributable to degraded water quality from one or 
a number of the following sources: siltation from poor land management 
practices within the cave's recharge area; contamination from numerous 
chemicals associated with point or non-point source pollution; or 
imbalances in dissolved oxygen, pH, or cation/anion exchange. The 
species may also be threatened with competition from limpets or from 
changes in the cave's normal hydrological cycles due to recent 
droughts. Because the sudden population decline and high magnitude of 
threats demonstrates a significant and imminent risk to the well-being 
of the Tumbling Creek cavesnail, we find that listing this species as 
endangered is appropriate.
    In making this determination, we have carefully assessed the best 
scientific and commercial information available regarding the past, 
present, and future threats faced by the Tumbling Creek cavesnail. From 
the discussion under Factor D of this section, it is clear that 
currently applicable Federal, State, and local laws, regulations, and 
ordinances, individually and collectively, do not provide adequate 
protection for the Tumbling Creek cavesnail or its habitat or assure 
that the species will continue to survive.
    We believe that the survival of the Tumbling Creek cavesnail now 
depends on protecting the delineated recharge area of Tumbling Creek 
Cave from further degradation and restoring and rehabilitating areas 
within the recharge area to improve the water quality in Tumbling 
Creek. The small remaining population is vulnerable to extinction from 
ongoing threats, as well as from random natural or human-caused events 
unless sufficient habitat is protected, water quality improves, and the 
current small population greatly increases in size. The recent rapid 
population decline makes it clear that this cavesnail is on the brink 
of extinction. By listing the Tumbling Creek cavesnail as an endangered 
species, we believe the additional protection, funding, and recognition 
that immediately become available to the species will greatly increase 
the likelihood that extinction can be prevented and the species 
ultimately recovered.
    We are making this rule effective immediately in order to ensure 
there is no gap in the protection provided by the Act to the Tumbling 
Creek cavesnail. The temporary protection that was provided by our 
emergency listing of the species on December 27, 2001, ends on August 
26, 2002. This final rule results in no change to the temporary 
protection and regulatory authority that was provided by the emergency 
listing, so there is no overriding need for a delayed effective date in 
order to provide adequate time to notify individuals, agencies, and 
organizations of new regulations that may affect them.

Critical Habitat

    Critical habitat is defined in section 3 of the Act as: (i) The 
specific areas within the geographical area occupied by a species, at 
the time it is listed in accordance with the Act, on which are found 
those physical or biological features (I) essential to the conservation 
of the species and (II) that may require special management 
considerations or protection; and (ii) specific areas outside the 
geographical area occupied by a species at the time it is listed, upon 
a determination that such areas are essential for the conservation of 
the species. ``Conservation'' means the use of all methods and 
procedures needed to bring the species to the point at which listing 
under the Act is no longer necessary.
    Section 4(a)(3) of the Act, as amended, and implementing 
regulations (50 CFR 424.12) require that, to the maximum extent prudent 
and determinable, we designate critical habitat at the time the species 
is determined to be endangered or threatened. However, our budget for 
listing and critical habitat activities is currently insufficient to 
allow us to immediately complete all of the listing actions required by 
the Act. Listing the Tumbling Creek cavesnail without designation of 
critical habitat will allow us to concentrate our limited resources on 
other listing actions that must be addressed, while allowing us to 
invoke protections needed for the conservation of this species without 
further delay. This is consistent with section 4(b)(6)(C)(i) of the 
Act, which states that final listing decisions may be issued without 
critical habitat designations when it is essential that such 
determinations be promptly published. The legislative history of the 
1982 Act amendments also emphasized this point: ``The Committee feels 
strongly, however, that, where biology relating to the status of the 
species is clear, it should not be denied the protection of the Act 
because of the inability of the Secretary to complete the work 
necessary to designate critical habitat. * * * The committee expects 
the agencies to make the strongest attempt possible to determine 
critical habitat within the time period designated for listing, but 
stresses that the listing of species is not to be delayed in any 
instance past the time period allocated for such listing if the 
biological data is clear but the habitat designation process is not 
complete.'' (H.R. Rep. No. 97-567 at 20 (1982)). If prudent and 
determinable, we will prepare a critical habitat proposal in the future 
at such time as our

[[Page 52888]]

available resources and other listing priorities under the Act will 

Available Conservation Measures

    Conservation measures provided to species listed as endangered or 
threatened under the Act include recognition, recovery actions, 
requirements for Federal protection, and prohibitions against certain 
practices. Recognition through listing results in public awareness and 
conservation actions by Federal, Tribal, State, and local agencies, 
private organizations, and individuals. The Act provides for possible 
land acquisition and cooperation with the State and requires that 
recovery actions be carried out for all listed species. The protection 
required of Federal agencies and the prohibitions against certain 
activities involving listed species are discussed, in part, below.
    Section 7(a) of the Act, as amended, requires Federal agencies to 
evaluate their actions with respect to any species that is proposed or 
listed as endangered or threatened, and with respect to its critical 
habitat, if any is being designated. Regulations implementing this 
interagency cooperation provision of the Act are codified at 50 CFR 
part 402. If a species is listed on an emergency basis, or is listed 
under a non-emergency listing proposal, section 7(a)(2) requires 
Federal agencies to ensure that activities they authorize, fund, or 
carry out are not likely to jeopardize the continued existence of such 
a species or to destroy or adversely modify its critical habitat. If a 
Federal agency action may adversely affect a listed species or 
adversely modify its designated critical habitat, the responsible 
Federal agency must initiate formal consultation with the Service. 
Section 7(a)(4) of the Act requires Federal agencies to confer with us 
on any action that is likely to jeopardize the continued existence of a 
proposed species or result in destruction or adverse modification of 
proposed critical habitat. Federal agency actions that may affect the 
Tumbling Creek cavesnail and may require consultation with the Service 
include, but are not limited to, those within the jurisdiction of the 
U.S. Forest Service, U.S. Army Corps of Engineers, Natural Resources 
Conservation Service, Environmental Protection Agency, and Federal 
Highway Administration.
    The Act and its implementing regulations found at 50 CFR 17.21 set 
forth a series of general prohibitions and exceptions that apply to all 
endangered wildlife. These prohibitions, in part, make it illegal for 
any person subject to the jurisdiction of the United States to take 
(including harass, harm, pursue, hunt, shoot, wound, kill, trap, 
capture, or collect; or attempt any such conduct), import or export, 
ship in interstate or foreign commerce in the course of commercial 
activity, or sell or offer for sale in interstate or foreign commerce 
any listed species. It also is illegal to possess, sell, deliver, 
carry, transport, or ship any such wildlife that has been taken 
illegally. Certain exceptions apply to Service agents and those of 
State conservation agencies.
    Permits may be issued to carry out otherwise prohibited activities 
involving endangered wildlife under certain circumstances. Regulations 
governing permits are codified at 50 CFR 17.22 and 17.23. For 
endangered species, such permits are available for scientific purposes, 
to enhance the propagation or survival of the species, and for 
incidental take in connection with otherwise lawful activities.
    As published in the Federal Register on July 1, 1994 (59 FR 34272), 
it is the Service's policy to identify, to the maximum extent 
practicable at the time a species is listed, those activities that 
would or would not constitute a violation of section 9 of the Act. The 
intent of this policy is to increase public awareness of the effect of 
the listing on proposed and ongoing activities within a species' range.
    We believe that, based on the best available information, the 
following actions are not likely to result in a violation of section 9, 
provided these actions are carried out in accordance with any existing 
regulations and permit requirements:
    (1) Possession of a Tumbling Creek cavesnail legally acquired prior 
to the effective date of this rule;
    (2) Actions that may affect the Tumbling Creek cavesnail that are 
authorized, funded, or carried out by a Federal agency, when the action 
is conducted in accordance with an incidental take statement issued by 
the Service under section 7 of the Act;
    (3) Actions that may affect the Tumbling Creek cavesnail that are 
not authorized, funded, or carried out by a Federal agency, when the 
action is conducted in accordance with an incidental take permit issued 
by the Service under section 10(a)(1)(B) of the Act. Applicants design 
a Habitat Conservation Plan (HCP) and apply for an incidental take 
permit. These HCPs are developed for species listed under section 4 of 
the Act and are designed to minimize and mitigate impacts to the 
species to the greatest extent practicable; and
    (4) Actions that may affect the Tumbling Creek cavesnail that are 
conducted in accordance with the conditions of a section 10(a)(1)(A) 
permit for scientific research or to enhance the propagation or 
survival of the species.
    We believe that the following actions could result in a violation 
of section 9; however, possible violations are not limited to these 
actions alone:
    (1) Unauthorized possession, collecting, trapping, capturing, 
killing, harassing, sale, delivery, or movement, including interstate 
and foreign commerce, or harming, or attempting any of these actions, 
of Tumbling Creek cavesnails without a permit (research activities 
where cavesnails are collected will require a permit under section 
10(a)(1)(A) of the Endangered Species Act);
    (2) Illegal discharges or dumping of toxic chemicals, silt, or 
other pollutants (point source and non-point source pollution) within 
the recharge area of Tumbling Creek Cave that alters or degrades the 
water quality of Tumbling Creek to the point that it results in death 
or injury to individuals of the species or results in degradation of 
cavesnail-occupied habitat;
    (3) Intentional release of exotic species (including, but not 
limited to, fish and crayfish) into Tumbling Creek that adversely 
affect the cavesnail;
    (4) Unlawful destruction or alteration of the species' occupied 
habitat (e.g., vandalism to Tumbling Creek); and
    (5) Violation of any discharge or water withdrawal permit within 
Tumbling Creek.
    We will review other activities not identified above on a case-by-
case basis to determine whether they are likely to result in a 
violation of section 9 of the Act. We do not consider these lists to be 
exhaustive and provide them as information to the public.
    Questions regarding whether specific activities will constitute a 
violation of section 9 should be directed to the Field Supervisor of 
the Columbia, Missouri Field Office (see FOR FURTHER INFORMATION 
    Requests for copies of the regulations regarding listed species and 
inquiries regarding prohibitions and permits may be addressed to the 
U.S. Fish and Wildlife Service, Endangered Species Permits, Bishop 
Whipple Federal Building, 1 Federal Dr., Fort Snelling, MN 55111-4056 
(612/713-5343, facsimile 612/713-5292).

National Environmental Policy Act

    The Service has determined that an Environmental Assessment, as 
defined under the authority of the National Environmental Policy Act of 
1969, need not be prepared in connection with

[[Page 52889]]

regulations adopted pursuant to section 4(a) of the Endangered Species 
Act, as amended. The Service published a notice outlining our reasons 
for this determination in the Federal Register on October 25, 1983 (48 
FR 49244).

Paperwork Reduction Act

    This rule does not contain any collections of information that 
require additional Office of Management and Budget (OMB) approval under 
the Paperwork Reduction Act, 44 U.S.C. 3501 et seq. An information 
collection related to the rule pertaining to permits for endangered and 
threatened species has OMB approval and is assigned control number 
1018-0094, which expires on July 31, 2004. This rule does not alter 
that information collection requirement. An agency may not conduct or 
sponsor, and a person is not required to respond to, a collection of 
information unless it displays a currently valid control number. For 
additional information concerning permits and associated requirements 
for endangered wildlife, see 50 CFR 17.21 and 17.22.

Effective Date

    This rule is effective upon publication. The Administrative 
Procedures Act provides Federal agencies a means under 5 U.S.C. (d)(3) 
for making rules effective less than 30 days following publication in 
the Federal Register for ``good cause.'' We believe that we have good 
cause for making this rule effective upon publication. The emergency 
listing rule for the Tumbling Creek cavesnail was published in the 
Federal Register on December 27, 2001 (66 FR 66803). That rule listed 
the Tumbling Creek cavesnail as endangered on an emergency basis for 
240 days through August 26, 2002. We are now publishing a final rule to 
the proposed rule (66 FR 66868) that we published on the same day as 
the emergency listing rule. To continue to provide this species the 
protections of the Act originally provided under the emergency rule, we 
must make this final rule effective upon publication.

References Cited

    A complete list of all references cited in this rulemaking is 
available upon request from the Field Supervisor, Columbia Field Office 


    The primary author of this proposed rule is Paul M. McKenzie, 
Ph.D., U.S. Fish and Wildlife Service, Columbia Field Office (see 

List of Subjects in 50 CFR Part 17

    Endangered and threatened species, Exports, Imports, Reporting and 
recordkeeping requirements, Transportation.

Regulation Promulgation

    For the reasons given in the preamble, we amend part 17, subchapter 
B of chapter I, title 50 of the Code of Federal Regulations, as set 
forth below:


    1. The authority citation for part 17 continues to read as follows:

    Authority: 16 U.S.C. 1361-1407; 16 U.S.C. 1531-1544; 16 U.S.C. 
4201-4245; Pub. L. 99-625, 100 Stat. 3500, unless otherwise noted.

    2. Amend Sec. 17.11(h) by adding the following, in alphabetical 
order under SNAILS, to the List of Endangered and Threatened Wildlife:

Sec. 17.11  Endangered and threatened wildlife.

* * * * *
    (h) * * *

                       Species                                                   Vertebrate
------------------------------------------------------                        population where                                  Critical       Special
                                                          Historic range       endangered or         Status      When listed     habitat        rules
           Common name              Scientific name                              threatened

                   *                  *                  *                  *                  *                  *                  *

                   *                  *                  *                  *                  *                  *                  *
Cavesnail, Tumbling Creek         Antrobia culveri...  U.S.A. (MO)........  NA.................  E                      731            NA            NA

                   *                  *                  *                  *                  *                  *                  *

    Dated: July 26, 2002.
Steve Williams,
Director, Fish and Wildlife Service.
[FR Doc. 02-20339 Filed 8-13-02; 8:45 am]