Geology topics

Sarah Greely

Publications and source records attributed to Sarah Greely.

2 recordsLinked to original sources

USGS2022

Injuries and abnormalities of the southwestern pond turtle (Actinemys pallida) in the Mojave River of California

The southwestern pond turtle ( Actinemys pallida ) is a semiaquatic turtle that occasionally spends time on land to bask, oviposit, make intermittent overland movements, and overwinter in terrestrial locations. Use of both aquatic and terrestrial environments exposes semiaquatic turtles to increased risk of injury or mortality from floods, predation attempts, and other environmental hazards (e.g., human activities such as vehicle strikes, etc.). We collected injury and morphological abnormality data from adult turtles at 3 study sites along the length of the Mojave River in San Bernardino County, California: 1 site on the upper half of the Mojave River (hereafter known as UHMRS) and 2 sites each on the lower half of the Mojave River (hereafter known as LHMRS). The studies were conducted when turtles were most active between May and October 1998–1999 and again from April to September 2016–2019. A total of 84 A. pallida were captured among all sites and all years. Seventeen percent ( n = 8) of the turtles captured at UHMRS exhibited shell abnormalities (natural variations in shell or bone morphology). Injuries (damage inflicted by force to the shell or body) occurred in 68% ( n = 26) of captured turtles at both the LHMRS sites combined and 78% ( n = 36) of turtles captured at the UHMRS alone. A total of 74% ( n = 62) of turtles had injuries at all sites combined. There was no statistical difference in the proportion of injured and noninjured turtles between the sexes for either the 2 LHMRS sites combined or the UHMRS. Mean carapace length was not significantly different between injured and noninjured turtles for these same sites. Injuries occurred in the majority of captured turtles at all sites and may be an indicator of the extent of threats facing these turtles.

Western North American Naturalist↗

USGS2021

Western pond turtles in the Mojave Desert? A review of their past, present, and possible future

= The western pond turtle ( WPT ) was formerly considered a single species ( Actinemys or Emys marmorata ) that ranged from southern British Columbia, Canada to Baja California, México. More recently it was divided into a northern and a southern species. WPTs are found primarily in streams that drain into the Pacific Ocean, although scattered populations exist in endorheic drainages of the Great Basin and Mojave deserts. Populations in the Mojave Desert were long thought to be restricted to the Mojave River, but recently another population was documented in Piute Ponds, a terminal wetland complex associated with Amargosa Creek on Edwards Air Force Base. WPT fossils in the Mojave Desert are known from the Miocene to the Pleistocene. Recently, Pleistocene fossils have been found as far into the desert as Salt Springs, just south of Death Valley. The oldest fossil records suggest that WPTs were present in wetlands and drainages of the geological feature known as the Mojave block prior to the uplift of the Sierra Nevada Range about 8 Ma and prior to the ~ 3 Ma uplift of the Transverse Ranges. Archaeological records document use of turtles by Native Americans for food and cultural purposes 1,000 or more years ago at the Cronese Lakes on the lower Mojave River and Oro Grande on the upper river. The first modern publication documenting their presence in the Mojave River was 1861. Museum specimens were collected as early as 1937. These fossil and early literature records support the indigenous status of WPTs to the Mojave River. However, mtDNA -based genetic evidence shows that Mojave River turtles share an identical haplotype with turtles on the California coast. Limited nuclear data show some minor differences. Overdraft of water from the Mojave River for municipal and agricultural uses, urban development, and saltcedar expansion are threats to the continued survival of WPTs in the Mojave River.

California, Nevada↗