Geology topics

Olin Feuerbacher

Publications and source records attributed to Olin Feuerbacher.

5 recordsLinked to original sources

USGS2016

Enhancing hatch rate and survival in laboratory-reared hybrid Devils Hole Pupfish through application of antibiotics to eggs and larvae

We evaluated the effectiveness of four antibiotics in enhancing the hatch rate, larval survival, and adult survival of hybrid Devils Hole Pupfish Cyprinodon diabolis (hybridized with Ash Meadows Amargosa Pupfish C. nevadensis mionectes ). Cephalexin (CEX; concentration = 6.6 mg/L of water), chloramphenicol (CAM; 50 mg/L), erythromycin (ERY; 12.5 mg/L), and trimethoprim sulfamethoxazole (TMP-SMX; 25 mg/L) were applied as a constant bath either to incubating eggs or to larvae that hatched from untreated eggs. Hatch rate was roughly doubled by incubation in the presence of CAM (68% hatch) and TMP-SMX (66%) relative to the control (28%). Cephalexin and ERY conferred no benefit upon the hatch rate. Among fry that hatched from treated eggs, there was no increase in 15-d larval survival. However, fish that hatched from eggs treated with CAM, ERY, and TMP-SMX demonstrated enhanced survival at 360 d (51.2, 38.4, and 43.6%, respectively) and at 540 d (22.6, 6.8, and 20.2%, respectively); the untreated control had no survivors to those time points. All groups of eggs treated with antibiotics showed reductions in bacterial colony-forming units (CFUs) at 24 h posttreatment. At 120 h posttreatment, CEX-treated eggs had CFU counts similar to those of the control, whereas the TMP-SMX-treated eggs had the lowest CFU counts. Eggs treated with CAM and ERY had similar CFU counts, which were significantly reduced from the control counts. Larvae that were treated with CAM and TMP-SMX within 12 h posthatch showed enhanced 15-d survival (74% and 72%, respectively) in comparison with the control (56%). For pupfish rearing efforts in which antibiotic use is appropriate, CAM and TMP-SMX appear to provide the greatest benefit, particularly when applied to incubating eggs rather than to hatched larvae.

North American Journal of Aquaculture↗

USGS2016

Design and testing of a mesocosm-scale habitat for culturing the endangered Devils Hole Pupfish

aptive propagation of desert spring fishes, whether for conservation or research, is often difficult, given the unique and often challenging environments these fish utilize in nature. High temperatures, low dissolved oxygen, minimal water flow, and highly variable lighting are some conditions a researcher might need to recreate to simulate their natural environments. Here we describe a mesocosm-scale habitat created to maintain hybrid Devils Hole × Ash Meadows Amargosa Pupfish ( Cyprinodon diabolis × C. nevadensis mionectes ) under conditions similar to those found in Devils Hole, Nevada. This 13,000-L system utilized flow control and natural processes to maintain these conditions rather than utilizing complex and expensive automation. We designed a rotating solar collector to control natural sunlight, a biological reactor to consume oxygen while buffering water quality, and a reverse-daylight photosynthesis sump system to stabilize nighttime pH and swings in dissolved oxygen levels. This system successfully controlled many desired parameters and helped inform development of a larger, more permanent desert fish conservation facility at the U.S. Fish and Wildlife Service’s Ash Meadows National Wildlife Refuge, Nevada. For others who need to raise fish from unique habitats, many components of the scalable and modular design of this system can be adapted at reasonable cost.

North American Journal of Aquaculture↗

USGS2015

Underwater videography outperforms above-water videography and in-person surveys for monitoring the spawning of Devils Hole Pupfish

The monitoring of threatened and endangered fishes in remote environments continues to challenge fisheries biologists. The endangered Devils Hole Pupfish Cyprinodon diabolis , which is confined to a single warm spring in Death Valley National Park, California–Nevada, has recently experienced record declines, spurring renewed conservation and recovery efforts. In February–December 2010, we investigated the timing and frequency of spawning in the species' native habitat by using three survey methods: underwater videography, above-water videography, and in-person surveys. Videography methods incorporated fixed-position, solar-powered cameras to record continuous footage of a shallow rock shelf that Devils Hole Pupfish use for spawning. In-person surveys were conducted from a platform placed above the water's surface. The underwater camera recorded more overall spawning throughout the year (mean ± SE = 0.35 ± 0.06 events/sample) than the above-water camera (0.11 ± 0.03 events/sample). Underwater videography also recorded more peak-season spawning (March: 0.83 ± 0.18 events/sample; April: 2.39 ± 0.47 events/sample) than above-water videography (March: 0.21 ± 0.10 events/sample; April: 0.9 ± 0.32 events/sample). Although the overall number of spawning events per sample did not differ significantly between underwater videography and in-person surveys, underwater videography provided a larger data set with much less variability than data from in-person surveys. Fixed videography was more cost efficient than in-person surveys (\$1.31 versus \$605 per collected data-hour), and underwater videography provided more usable data than above-water videography. Furthermore, video data collection was possible even under adverse conditions, such as the extreme temperatures of the region, and could be maintained successfully with few study site visits. Our results suggest that self-contained underwater cameras can be efficient tools for monitoring remote and sensitive aquatic ecosystems.

Nevada↗

USGS2015

Propagation of hybrid Devils Hole Pupfish × Ash Meadows Amargosa Pupfish

Recent censuses of Devils Hole Pupfish Cyprinodon diabolis revealed that fewer than 100 individuals currently remain in the wild. Captive propagation is among actions being considered to prevent their extinction, but no pure-strain Devils Hole Pupfish were available for broodstock. To help provide emergency information, we investigated techniques to propagate their most closely related relative, hybrid Devils Hole Pupfish C. diabolis × Ash Meadows Amargosa Pupfish C. nevadensis mionectes. We tested various temperatures and larval feeds with respect to egg production, larval survival, and growth. Larval survival and growth were similar from 24°C to 32°C and egg production peaked at static 28°C; however, reducing water temperatures to 23°C and then raising them to 28°C resulted in even higher production. Larvae fed infusoria, Rio Grande Silvery Minnow Chow (RGSM), or Zeigler larval diet (ZLD) had the highest survival (79.4, 71.6, and 73.4%, respectively), and those fed Otohime (OTO) had the lowest survival (60.8%), although OTO provided greatest (14 mm) 30-d growth. Supplementation of RGSM or ZLD with Artemia nauplii increased growth but decreased survival. Larval production was maximized by placing six spawning mops, constructed of yarn and tile, in each of four 437-L parental aquaria, stocked with 24 adult fish each (1:1 sex ratio) for 3 d, to attract adults and provide spawning substrate. A 30% water change conducted on the same day of mop placement lowered water temperature from 28°C to 23°C. Water temperature was raised back to 28°C over 48 h. After 3 d, mops were transferred to hatching aquaria that were held at 28°C and aerated until larval hatch. Although some differences likely exist in effective propagation techniques for hybrid and pure-strain Devils Hole Pupfish, these data help provide initial recommendations to aid recovery.

North American Journal of Aquaculture↗

USGS2014

Growth and survival of Apache Trout under static and fluctuating temperature regimes

Increasing stream temperatures have important implications for arid-region fishes. Little is known about effects of high water temperatures that fluctuate over extended periods on Apache Trout Oncorhynchus gilae apache , a federally threatened species of southwestern USA streams. We compared survival and growth of juvenile Apache Trout held for 30 d in static temperatures (16, 19, 22, 25, and 28°C) and fluctuating diel temperatures (±3°C from 16, 19, 22 and 25°C midpoints and ±6°C from 19°C and 22°C midpoints). Lethal temperature for 50% (LT50) of the Apache Trout under static temperatures (mean [SD] = 22.8 [0.6]°C) was similar to that of ±3°C diel temperature fluctuations (23.1 [0.1]°C). Mean LT50 for the midpoint of the ±6°C fluctuations could not be calculated because survival in the two treatments (19 ± 6°C and 22 ± 6°C) was not below 50%; however, it probably was also between 22°C and 25°C because the upper limb of a ±6°C fluctuation on a 25°C midpoint is above critical thermal maximum for Apache Trout (28.5–30.4°C). Growth decreased as temperatures approached the LT50. Apache Trout can survive short-term exposure to water temperatures with daily maxima that remain below 25°C and midpoint diel temperatures below 22°C. However, median summer stream temperatures must remain below 19°C for best growth and even lower if daily fluctuations are high (≥12°C).

Transactions of the American Fisheries Society↗