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<br />. <br /> <br />. <br /> <br />vegetation cover over the growing season, with 11.2% to 16.1% of the estimated total <br />primary habitat occurring below the 45,000 cfs stage in 1995, and 7,0-12,0% of the <br />estimated total primary habitat occurring downslope from the 45,000 cfs stage from 20 <br />April 1996 through 3 October 1997. The total estimated area of primary habitat was <br />905.7 m2 (0.22 acres), equivalent to the area of secondary habitat, and the total <br />vegetated area was 1,811.4 m2 (0.44 acres) in June, 1995. Photogrammetric analyses <br />indicate that the upper primary habitat area in November 1997 had decreased to <br />approximately 720 m2 (L.E. Stevens, personal communication), <br /> <br />The total estimated Vaseys Paradise KAS population rose from 18,476 snails in March <br />1995 to as many as 103,653 snails in September, 1995 as reproduction took place in <br />middle to late summer (Stevens et aL 1997b), The proportion of the total estimated <br />KAS population occurring below the 45,000 cfs stage was 3.3% in March, 11.3% in <br />June, and 16.4% in September in 1995, Three years of population data indicate that <br />the KAS population sustains a 40%-80% reduction through over-wintering mortality <br />(Kanab Ambersnaillnteragency Work Group 1997b). <br /> <br />The KAS population and habitat lying downslope from the 45,000 cfs stage was <br />scoured in the BHBF in 1996 (Kanab Ambersnaillnteragency Work Group 1997a). <br />Habitat recovery was delayed in 1996 and 1997 because of high flows (20,000 to <br />28,000 cfs) that resulted from high reservoir forecasts and large summer monsoon <br />floods on the Paria River, particularly in 1997. Analyses of oblique photographs taken <br />in November of 1994-1997 indicate that no major changes have occurred in the <br />vegetation cover lying upslope from the 70,000 cfs stage (Kanab Ambersnail <br />Interagency Work Group 1997b). In October 1997, 101.22 m2 (12% of the estimated <br />total primary habitat at Vaseys Paradise existed downslope from the 45,000 cfs stage. <br />October 1997 population data indicate that an estimated 2,187 KAS exist downslope <br />from the 45,000 cfs stage, 6.4% of the estimated total KAS existing at Vaseys Paradise <br />(Kanab Ambersnaillnteragency Work Group 1997b). Also, these data indicate that the <br />Vaseys Paradise KAS habitat and population to pre-1996 BHBF conditions has <br />required more than 2 full years to recover. <br /> <br />Life Requisites <br /> <br />Monkeyflower, sedge, smartweed and watercress are persistent aquatic wetland or <br />hydrophytes (Kearney and Peebles 1960), and KAS is virtually completely restricted to <br />those species at Vaseys Paradise (Stevens et aL 1997b, Kanab Ambersnail <br />Interagency Work Group 1997a,b), KAS were rare to absent on other plant species <br />and bare substrata. <br /> <br />Introduction of watercress at Vaseys Paradise provided KAS with an alternate host <br />plant. KAS densities are generally higher on watercress than on the native host plants <br />during the growing season (Kanab Ambersnaillnteragency Work Group 1997b). <br />Although watercress is an annual species, its life cycle at Vaseys Paradise is <br />unpredictable, In part, this irregularity is due to the unithermal warm flows of the spring <br /> <br />1998 GCD Beach/Habitat Building Flow 8 <br /> <br />Biological Assessment <br />