The santa ANA sucker (catastomus santaanae, hereafter sucker) is a federally threatened species found in the santa ANA watershed, the santa clara river, and the upper regions of the LOS angeles and…

The santa ANA sucker (catastomus santaanae, hereafter sucker) is a federally threatened species found in the santa ANA watershed, the santa clara river, and the upper regions of the LOS angeles and SAN gabriel rivers. Threats to the sucker in its current range include habitat loss due to modification and fragmentation, water quality degradation, introduction of nonnative species, and large-scale water removal for municipal purposes. These threats are driven by the ongoing urbanization and human population growth in southern california. Climate change and non-environmental flowshave modified the hydrology of the urban santa ANA river since santa ANA sucker life history was first studied. This has left a knowledge GAP about basic santa ANA sucker biology needed to conserve remaining populations of the species.while monitoring of sucker has improved in recent years, there are still many gaps in our understanding of sucker biology and life history, particularly with respect to early life stages that are likely highly sensitive to environmental conditions. Indeed, only one study has examined the EGG survival and larval development of sucker (greenfield ET AL. 1970). Our proposed work will improve our understanding of sucker EGG and larval mortality and development under the range of temperatures found in their extant urbanized habitat in the santa ANA river in SAN bernardino and riverside counties. This will provide badly needed information to researchers and managers about the existing (or how changes to the) thermal regime in the santa ANA river may impact sucker population viability.