Draft terrestrial resources biological assessment
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- 3.2.1 Relevant Habitat Unit: Vernal Pool Complexes within the Action Area
- 3.2.2 Shelter
- 3.2.3 Feeding
- 3.2.4 Reproduction
- 3.2.5 Habitat Connectivity and Migration
3.2 Vernal Pool Fairy ShrimpVernal pool fairy shrimp are listed as threatened under the federal ESA. Critical habitat has been designated and mapped by the USFWS for this species within the project study area in the vicinity of the southern terminus of Agate Road, the intersection of Agate Road and Touvelle Road, and east of the intersection of Highway 62 and Hoover Avenue (68 FR 46684). See comment above. This restates the paragraph above. Can you combine? Portions of this mapped critical habitat occur in the northern portion of both Build Alternatives. Vernal pool fairy shrimp are currently known to occur in vernal pools, often less than 0.05 acre in size, in the southern and central valleys of California and the Agate Desert surrounding Medford in Oregon. Three areas within the project study area have been mapped by the USFWS as vernal pool fairy shrimp designated CH: Agate Road north of the existing OR 62 intersection; Agate Road centered on Touvelle Road; and the existing OR 62 alignment just south of the West Dutton Road (Figures 5-3, 5-4 and 5-5). Although these areas are federally-designated as critical habitat for vernal pool fairy shrimp, the primary constituent elements (PCE) of critical habitat as established by the USFWS are lacking in these mapped areas. Vernal pool fairy shrimp critical habitat PCEs are based on the presence of vernal pools that contain organic food sources and inorganic debris for shelter (50 CFR 17.97). Based on field investigations, these mapped areas lack the characteristic vernal pools required for critical habitat identified by the USFWS. Areas mapped as critical habitat within the project study area have all been disturbed and include road shoulders, active pasture, and vacant land. As such, it is apparent that vernal pool DCH does not exist within the project footprint. VPFS are highly dependent on vernal pools and the suitability of habitat they provide. Degradation of this habitat type, either directly or indirectly, can severely impact the survivability of a viable population. 3.2.1 Relevant Habitat Unit: Vernal Pool Complexes within the Action AreaVernal pools are unique ephemeral wetland ecosystems that form in shallow depressions within gently undulating landscapes. They are typically underlain by bedrock or a duripan (hardpan) soil layer that restricts the downward movement of water through the soil profile. The pools become inundated by local hydrology during the fall/winter rainy season and dry out during the late spring and summer through evapotranspiration. This alternation between inundation and drought greatly limits the flora and fauna species that are able to inhabit vernal pool habitat. As a result, many plant and wildlife species inhabiting vernal pools are endemic, with several being listed as threatened or endangered under the federal ESA (Williamson et. al, 2005). Insert paragraph about historic VPC cover, what’s left, and the quality of the VPCs within the action area (from section 3.1) VPCs account for the second smallest land cover within the project study area. There are three major VPCs within the project study area: between the Medco Haul Road and the existing OR 62, just north of Upton Creek; north and south of Whetstone Creek; and west of the terminus of West Dutton Road and east of Agate Road. In addition, there are scattered vernal pools throughout the vicinity of the project study area. Vernal pools may provide habitat for the federally-listed vernal pool fairy shrimp. In addition, vernal pool complexes provide habitat for two endangered plant species, Cook’s lomatium and large-flowered woolly meadowfoam. However, the majority of vernal pools within the project study area are disturbed and degraded and are typically dominated by non-native plant species as soon as water in the pools evaporates. All of the vernal pools in the project study area have been degraded by the invasion of non-native plants, grazing, road construction and illegal trash dumping. All vernal pool complexes identified during the 1998-2000 field work (MB&G 2008) were revisited by MB&G staff on several occasions from 2004-2007 to confirm the continued presence of the vernal pools and to note any changes that might affect habitat quality for vernal pool fairy shrimp. However, no additional protocol surveys for vernal pool fairy shrimp were conducted for the project study area after 2000. 3.2.2 ShelterVernal pool fairy shrimp are defenseless, and therefore occupy very temporary ponds, where aquatic vertebrate predators cannot survive. The cyclical wetting and drying of vernal pools allows for a dynamic habitat which only a narrow range of species can tolerate, thereby limiting the number of predators that are adapted to these kinds of environmental conditions. 3.2.3 FeedingBiological soil crusts are generally regarded as indicative of healthy landscapes due to the resistance they impart to the soil surface against wind and water erosion. On the Agate Desert, the crust appears to also function as living mulch by retaining soil moisture, fixing atmospheric nitrogen, and discouraging annual weed growth. Vernal pool fairy shrimp feed on algae, bacteria, protozoa, rotifers, and detritus and plankton dependent on these crusts by scraping and straining them from surfaces within the vernal pool. They produce a gluey substance and mix it with their food before eating (USFWS 2010a). 3.2.4 ReproductionVernal pool fairy shrimp typically hatch when the first rains of the year fill vernal pools. Under typical conditions, they mature in about 41 days and live for a single season, while there is water in the pools. Females produce thick-shelled cysts during the summer. The cysts become embedded in the dried mud are frozen for varying lengths of time. The cysts hatch when the rains come again. It appears that prior freezing and/or drying seems to be necessary for the eggs to hatch (USFWS 2011). The habitat of the fairy shrimp is highly fragmented throughout their range due to conversion of natural habitat for urban and agricultural uses. This fragmentation results in small isolated fairy shrimp populations. Ecological theory predicts that such populations will be highly susceptible to extinction due to chance events, inbreeding depression, or additional environmental disturbance. Should an extinction event occur in a population that has been fragmented, the opportunities for recolonization are thought to be greatly reduced due to physical (geographical) isolation from other (source) populations (USFWS 2011). Within the project action area, vernal pool complexes are already isolated through existing land use practices (agriculture, grazing and existing roadways). This isolation includes hydrologic fragmentation generally caused by roads or other developments that disconnect a population in one pool with other pools in the complex, thereby creating a population bottleneck. Physical barriers such as roads and canals may also unsuitably deepen a vernal pool upstream of a barrier. Surface runoff can be altered by trenching and other activities that change amounts, patterns, and direction of runoff to ephemeral swales and pools. 3.2.5 Habitat Connectivity and MigrationVPFS are dependent upon the hydrologic connectivity between pools to prevent inbreeding and population declines. Their small size greatly limits the species ability to travel long distances to obtain new genetic material. This, along with their exclusive use of the aquatic environment and its temporary time-length of availability, confines the shrimp to highly localized areas. Disruption of the hydrologic connectivity between pools would reduce the affected population to inbreeding and eventually discontinuation (USFWS 2003). Directory: HWY62 -> Terrestrial BA Terrestrial BA -> Draft Terrestrial Resources Biological Assessment oregon highway 62 corridor solutions project Download 486.24 Kb. Share with your friends:
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