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<br />Arizona Game and Fish Department
<br />Draft EA: Kanab Ambersnail
<br />
<br />June 1998
<br />Page 19
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<br />147,8 mi RR Seep have more than one species of landsnails, Most proposed sites only harbor
<br />populations ofCatinel/a (succineid landsnails), Physa=Physel/a (aquatic snails), and/or Deroceras
<br />(marsh slugs), While KASs and Catinel/a coexist at both VP and 3L, they appear to spatially
<br />segregate along steep moisture gradients, and may have distinct niche requirements (pers, comm, L
<br />Stevens), Stevens also contends that an introduced species to a site with multiple assemblages and
<br />little niche overlap, may substantially affect niche segregation, While Thunder River and Roaring
<br />Springs may fit this description (each having at least eight different genera oflandsnails [Spamer arid
<br />Bogan 1993; Stevens et al, 1997a; Sorensen and Kubly 1997; pers, comm, E, North]), the only close
<br />succineid neighbor would be Catinel/a, KAS and Catinel/a are more "amphibious" in habitat
<br />selection (close proximity to water), than say the talussnails Oreohelix or Sonorel/a, which prefer
<br />drier litter/duff and limestone talus, Likewise, succineid snails are pulmonates (air-breathing), and
<br />will not displace aquatic snails for habitat. Documented evidence of species displacement in Grand
<br />Canyon region mollusks is lacking,
<br />
<br />Hoffinan (1990) indicates that competition occurs in the sympatric species of Sonorel/a grahamensis
<br />and S. imitator in the Pinaleno Mountains, southern Arizona, Character displacement may occur
<br />between closely related species sharing the same habitat, as documented in studies of Cepaea spp,
<br />(Fretter and Peake 1978), The degree of relatedness in both of these examples of competition are
<br />congeneric (same genus); familial and ordinal levels of mollusks are unlikely to compete (pers, comm,
<br />J Hoffman),
<br />
<br />J Hoffinan (pers, comm,) believes that most mollusk genera coexist successfully within the same
<br />habitat, even species of the same genus if they are not extremely similar, Oxyloma and Catinel/a,
<br />both in the family Succineidae, are successfully coexisting at VP and -9 Mile Spring (-9M) Lee's
<br />Ferry (i,e" the Niobrara ambersnail, Oxyloma haydeni haydeni), The widespread distribution of
<br />Catinella spp, indicates less stringent habitat requirements than Oxyloma spp, AGFD has observed
<br />Catinella at -9M to be more abundant in rushes, sedges, and various grasses, with less overlap in O.
<br />h. haydeni habitat of cattails and watercress, More competition would be expected ifKAS and 0.
<br />h. haydeni occupied the same site, with a greater overlap of habitat use,
<br />
<br />Interagency studies at VP confinn that KAS is an intennediate host for the parasitic trematode,
<br />Leucochloridium cyanocittae (pers, comm, p, Lewis Jr.; Stevens et ai, 1997a), In June 1998, two
<br />KASs from the Utah population were observed with parasite sporocysts (pers, comm, V, Meretsky),
<br />Trematode parasitism of KASs appears to be regionally dispersed, not a local phenomenon,
<br />Furthermore, if this parasite is being distributed by passerine birds throughout Grand Canyon and
<br />vicinity, infestation at new establishment sites may be uncontrollable,
<br />
<br />Current research has not demonstrated significant effects (either positive or negative) of
<br />Leucochloridium on KASs life cycle, population dynamics, or reproduction, Stevens and Price
<br />(1998) believe infected KASs may have a lower level of fitness and/or reduced reproductive potential,
<br />In August 1997, two parasitized KASs (both 15 mm in size) were found to be capable oflaying egg
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