<br />Arizona Game and Fish Department
<br />Draft EA: Kanab Ambersnail
<br />
<br />June 1998
<br />Page 3
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<br />et al. 1997a), They are most abundant under fallen cattail stalks, decadent monkeyflower litter, or
<br />young watercress (USFWS 1995),
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<br />Biology. KASs have an approximately annuallifecycle, and reportedly live 12-15 months (Clarke
<br />1991), They emerge from winter hibernation in early spring with the onset of warm weather, and
<br />begin reproducing throughout the late spring and summer months, Peak reproduction typically
<br />occurs in the late summer (July-August), when densities of mature KASs are highest. A seasonal,' ,
<br />decline of KASs occurs in early fall with gradual die-off's of mature individuals, while young KASs
<br />go into winter donnancy (Stevens et al, 1997a), KASs are hermaphroditic, possessing both male and
<br />female sex organs (Pi1sbry 1948), Young snails develop from gelatinous egg masses attached to wet
<br />plant litter, leaves, or stems, Fully mature KASs can have shell lengths up to 20 mm,
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<br />Threats to KAS Existence. The Utah population (Three Lakes; 3L) is threatened by habitat loss and
<br />possible extirpation by planned commercial development (USFWS 1995), The VP population is
<br />threatened by habitat loss and incidental take from high flow water releases from Glen Canyon Dam
<br />(USFWS 1995), This population experienced habitat loss and incidental take during an experimental
<br />45,000 cfs (\275 m3/s) stage BHBF in March 1996 (Stevens et al, 1997a, 1997b), BHBFs are
<br />controlled floods from Glen Canyon Dam designed to redistribute sediments from the channel bottom
<br />to the river banks. Natural disturbances to VP may also threaten the KAS population, The talus slope
<br />upon which KAS reside at VP was created in the past by an unknown number of debris flows from
<br />an ephemeral wash that exits above the VP spring orifices, and future flows could negatively impact
<br />the VP KAS population,
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<br />Interagency KAS investigators have identified two potential biological threats (both naturally
<br />occurring at VP) that may aff'ect KAS, Deer mice (Peromyscus spp,) are suspected to be KASs
<br />predators (Stevens et al, 1997b), The parasitic trematode (flatworm) in the genus Leucochloridium
<br />may be another biological threat to individual KASs, Neither of these biological threats are
<br />detrimental to VP KAS at the population level, based on information gathered to date, The deer
<br />mouse population at VP is relatively small, ,and there are numerous other invertebrate prey species
<br />available to the mice, The trematode parasite is naturally occurring in succineid snails, it is present
<br />in both Utah and Arizona populations ofKAS (pers, comm, V, Meretsky), Based on interagency
<br />studies (1995-1997), Leucochloridium is estimated to be present in <10% ofVP KAS (Stevens et
<br />al, 1997a, 1997b; IKAMT 1998),
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<br />Ecological Studies. The USFWS 1994 Biological Opinion on the operation of Glen Canyon Dam
<br />required that the VP KAS population and habitat be quantified, The 1996 Biological Opinion
<br />specifically addressed the incidental take of VP KAS and habitat loss from the March 1996
<br />experimental BHBF. An interagency teall;l,of researchers began ecological studies on KAS at VP in
<br />1994 and continued monitoring through 1997, Representatives of the following agencies/institutions
<br />participated in Kanab Ambersnail Working Group (KAWG) activities: AGFD, Grand Canyon
<br />Monitoring and Research Center (GCMRC), National Park Service (NPS), Northern Arizona
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