Citation:

JAEGER, J. R., D. F. BRADFORD, C. DROST, AND L. GELCZIS. IMPLICATIONS OF THE DISCOVERY OF RANA YAVAPAIENSIS IN THE WESTERN GRAND CANYON TO THE CONSERVATION STRATEGY FOR RANA ONCA. Presented at World Conservation Union, Declining Amphilbian Populations Task Force, CA/NV Working Group, Berkeley, CA, January 13 - 14, 2005.

Impact/Purpose:

The primary objectives of this research are to:

Develop methodologies so that landscape indicator values generated from different sensors on different dates (but in the same areas) are comparable; differences in metric values result from landscape changes and not differences in the sensors;

Quantify relationships between landscape metrics generated from wall-to-wall spatial data and (1) specific parameters related to water resource conditions in different environmental settings across the US, including but not limited to nutrients, sediment, and benthic communities, and (2) multi-species habitat suitability;

Develop and validate multivariate models based on quantification studies;

Develop GIS/model assessment protocols and tools to characterize risk of nutrient and sediment TMDL exceedence;

Complete an initial draft (potentially web based) of a national landscape condition assessment.

This research directly supports long-term goals established in ORDs multiyear plans related to GPRA Goal 2 (Water) and GPRA Goal 4 (Healthy Communities and Ecosystems), although funding for this task comes from Goal 4. Relative to the GRPA Goal 2 multiyear plan, this research is intended to "provide tools to assess and diagnose impairment in aquatic systems and the sources of associated stressors." Relative to the Goal 4 Multiyear Plan this research is intended to (1) provide states and tribes with an ability to assess the condition of waterbodies in a scientifically defensible and representative way, while allowing for aggregation and assessment of trends at multiple scales, (2) assist Federal, State and Local managers in diagnosing the probable cause and forecasting future conditions in a scientifically defensible manner to protect and restore ecosystems, and (3) provide Federal, State and Local managers with a scientifically defensible way to assess current and future ecological conditions, and probable causes of impairments, and a way to evaluate alternative future management scenarios.

Description:

The minimum historical range of the relict leopard frog, Rana onca, comprises the drainages of the Virgin and Colorado rivers from the vicinity ofHurricane, Utah, to Black Canyon below Lake Mead, in Nevada and Arizona. Extant populations are known near only the Black Canyon and Overton Arm of Lake Mead. One adjacent area that may contain extant populations remains largely unsurveyed. This is the Colorado River and tributary drainages upstream from the confluence with the Virgin River (part of Lake Mead) in the western portion of the Grand Canyon. A few sites in this area were recently surveyed and a population of frogs physically similar to R. onca was found in Surprise Canyon (a tributary drainage). A mitochondrial DNA sequence analysis of several specimens showed that these individuals were more closely related to the lowland leopard frog, Rana yavapaiensis, than to R. onca. Surprise Canyon is situated within the Potential Management Zone (PMZ) for R. onca, as identified in the draft Conservation Assessment and Strategy (CAS). Discovery of the Surprise Canyon frogs within the PMZ has raised new concerns about the potential for hybridization. This threat impedes the primary recovery mechanism for R. onca identified in the draft CAS, i.e., to establish a number of new populations within the PMZ. Translocation sites are critically needed, but the majority of potential sites observed to date appear to be severely degraded. The western Grand Canyon was viewed as a promising area for establishing populations. Without further information, however, the threat of hybridization with the Surprise Canyon frogs renders questionable the suitability of this portion of the PMZ. The uncertainty is acute because the extent and identity of ranid frogs within the western Grand Canyon remains mostly unknown.

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