Modeling the impact of sea level rise on endangered deer habitat.

Numerous unique flora and fauna inhabit the Lower Florida Keys, including the endangered Florida Key deer, found nowhere else. In this vulnerable habitat of flat islands with low elevation, accelerated sea level rise poses a threat. Predicting the impact of sea level rise on vegetation and wildlife is crucial. This study used 5 Intergovernmental Panel on Climate Change (IPCC) sea level rise scenarios to assess their effects on No Name Key, Florida. The goal was to estimate changes in the Florida Key deer population relative to sea level rise using a lidar-derived elevation data and a vegetation map. The method used 2 cases to model the sea level rise impact. In Case 1, total non-submerged area at current sea level was determined. Using 5 IPCC scenarios, a new total non-submerged land area was estimated, and deer numbers were predicted for each scenario. In Case 2, upward migration of coastal vegetation combined with the coastal squeeze process was modeled. A distinct elevation range for each vegetation type at the current sea level was determined. Vegetation ranges were redistributed based on respective elevation ranges in the sea level rise scenarios. Areas for each vegetation type were recalculated, and Key deer numbers were estimated for each sea level rise scenario. Results under the worst emission scenario showed the following: (1) for case 1, the land area was reduced to 30 % of the current land area, corresponding to having about 27 deer, and (2) for case 2, the land area was reduced to 70 % of the current land area, having about 54 deer on No Name Key. The results indicated reduced non-submerged land area and less upland vegetation, particularly hardwoods/hammocks, by the year 2100. As less land area is available, a decline in Key deer population is expected as sea levels rise. Since Key deer favor upland vegetation, habitat affected by sea level rise will likely support a smaller deer population. The findings emphasize the need for precise, timely predictions of sea level rise impacts and long-term conservation strategies. Specifically designed measures are required to protect and maintain endangered wildlife, such as the Florida Key deer, residing on these vulnerable islands.

Suitability of containerized toxicant to control Solenopsis invicta (Hymenoptera: Formicidae) threatening cave species in Bexar County, Texas.

Several protected troglobitic invertebrate species are known to occur in caves on Joint Base San Antonio-Camp Bullis, Bexar County, Texas, United States. The United States Fish and Wildlife Service (USFWS) identified red-imported fire ant Solenopsis invicta (hereafter RIFA) (Buren 1972) as the primary threat to cave species' nutrient sources, cave crickets, Ceuthophilus secretus (Scudder 1894). Per the service's recommendations, Joint Base San Antonio-Camp Bullis currently implements boiling water mound injections with digging for RIFA control. However, treatment effectiveness is highly variable and largely dependent on the time of day, weather, and personnel diligence. Toxicants have been used for RIFA treatment throughout the world, but concerns exist that traditional applications of toxicant bait around caves might be accessible and inadvertently affect nontarget arthropods, including cricket populations. To mitigate this accessibility, physically limiting access to the toxicant from crickets may be an option. Our objectives were to (i) compare and evaluate the effectiveness of Amdro (Hydramethylnon) and Advion (Indoxacarb) granular baits housed in Ants-No-More Bait Stations (Kness MFG. Inc., Albia, IA) and (ii) evaluate the distance of effectiveness of each bait within a bait station. Ultimately, we observed a 98% reduction in RIFA mound abundance from both baits. Additionally, RIFA mounds within 10 m of the containerized toxicant were reduced by 70%. Our pilot study suggested that Ants-No-More Bait Stations are an effective way to reduce RIFA mounds by 70% if placed 10 m from each other. In practice, this could include bait stations completely covering a particular distance to a cave entrance or fewer bait stations in a ring barrier at a single radial distance to a cave entrance. Containerized toxicants may be a cost-effective and safe RIFA control option around protected cave environments, but further studies are needed to determine potential effects on nontarget arthropods, optimal bait station configuration, and potential effects of biomagnification.

Evaluation of survivorship and annulus validation in calcein-stained freshwater unionid mussels.

Unionid mussels deposit growth rings (annuli) within the shell, which can be used to estimate age and growth. Thin-sectioning is a common technique for counting annuli, wherein a cross-section of a shell valve is taken and evaluated by multiple readers. Correctly identifying annuli can be challenging because ambiguous annuli can bias growth estimates. Staining with calcein, a fluorescent chemical, is a technique that has been used with marine and freshwater species to improve accuracy of growth estimates. This method chelates calcium, causing a permanent mark that fluoresces under ultraviolet light. Calcein has seen limited testing on unionid mussels so it remains unclear if this method has adverse effects on survival and growth. We evaluated calcein against 2 concentrations (125 mg L-1 and 250 mg L-1) at 2 exposure times (12 and 24 h) on Cyclonaias pustulosa, a common North American unionid. Survivorship remained above 80% 6 months post-immersion. Mark quality and retention for 250 mg L-1 were high for both 12- and 24-h immersions, although historical annuli were not highlighted. These findings corroborate studies indicating calcein immersion is generally safe and effective in juveniles and adults and suggest it may be useful in validating new growth.

Thermal tolerances of Popenaias popeii (Texas hornshell) and its host fish from the Rio Grande Basin, Texas.

Freshwater mussels are particularly sensitive to hydrologic changes, including streamflow and temperature, resulting in global decline. The Devils River in south-central Texas harbors the endangered freshwater mussel Popenaias popeii (Unionidae; Texas hornshell). There is concern that water withdrawals from the underlying aquifer may be negatively impacting this species. To assess this risk, we evaluated upper thermal tolerances (LT05 and LT50) of larvae (glochidia) and juveniles from two sites. After being acclimated to 27 °C, glochidia were subjected to five experimental temperatures (30, 32, 34, 36, and 38 °C) and non-acclimated control (20 °C) for 12-h and 24-h while juveniles were subjected to three experimental temperatures (30, 32, and 36 °C) and non-acclimated control (20 °C) for 96-h. We overlaid tolerance estimates against in situ water temperature and discharge data to evaluate thermal exceedances. Additionally, we reviewed upper thermal tolerances of P. popeii's presumed host fish (Carpiodes carpio, Cyprinellas lutrensis, and Moxostoma congestum) and their congeners. Stream temperatures only occasionally exceeded mussel LT05/50 and fish CLMax/LTMax, likely due to the Devils River's large spring input, highlighting the importance of protecting spring flows. We provide a practical framework for assessing hydrological needs of aquatic ectotherms, including the parasite-host relationship, which can be used to optimize environmental management.

Using a multi-model ensemble approach to determine biodiversity hotspots with limited occurrence data in understudied areas: An example using freshwater mussels in México.

Species distribution models (SDMs) are an increasingly important tool for conservation particularly for difficult-to-study locations and with understudied fauna. Our aims were to (1) use SDMs and ensemble SDMs to predict the distribution of freshwater mussels in the Pánuco River Basin in Central México; (2) determine habitat factors shaping freshwater mussel occurrence; and (3) use predicted occupancy across a range of taxa to identify freshwater mussel biodiversity hotspots to guide conservation and management. In the Pánuco River Basin, we modeled the distributions of 11 freshwater mussel species using an ensemble approach, wherein multiple SDM methodologies were combined to create a single ensemble map of predicted occupancy. A total of 621 species-specific observations at 87 sites were used to create species-specific ensembles. These predictive species ensembles were then combined to create local diversity hotspot maps. Precipitation during the warmest quarter, elevation, and mean temperature were consistently the most important discriminatory environmental variables among species, whereas land use had limited influence across all taxa. To the best of our knowledge, our study is the first freshwater mussel-focused research to use an ensemble approach to determine species distribution and predict biodiversity hotspots. Our study can be used to guide not only current conservation efforts but also prioritize areas for future conservation and study.

Effectiveness of Spayvac for reducing white-tailed deer fertility.

Overabundant white-tailed deer (Odocoileus virginianus) populations have been reported in many urban and suburban communities across the United States. Large populations of deer can potentially increase the risk of human-wildlife conflicts, such as deer-vehicle collisions, transmission of disease to humans, and vegetation damage. In 2003, efforts to control white-tailed deer numbers were initiated at the National Aeronautical and Space Agency's (NASA) Lyndon B. Johnson Space Center (JSC) in Houston, Texas, using the long-lasting, single-dose contraceptive SpayVac. Our objectives were to evaluate the effectiveness of SpayVac for reducing white-tailed deer fertility and determine the partial cost for treatment. Between 2003 and 2004, we monitored 45 adult female deer (34 treated with SpayVac, 11 controls treated with a placebo). Fawning rate over 2 yr for deer treated with SpayVac >30 days prior to the rut was 0% (n=31), whereas the fawning rate for control deer was 78% (n=11). Inoculation 1 mo prior to the breeding season was sufficient time to achieve fertility control. We conclude that SpayVac can effectively reduce the fertility of urban white-tailed deer.

TRYPANOSOMA CRUZI IN FREE-RANGING MAMMALIAN POPULATIONS IN SOUTH TEXAS, USA.

Chagas disease, also known as American trypanosomiasis, is caused by the flagellate protozoan Trypanosoma cruzi. It is a significant health concern in South and Central America, where millions of people are infected or at risk of infection, and is an emerging health concern in the US. The occurrence of Chagas disease in natural environments is supported by mammal host species, but those primary species may vary based on geographic location. In South Texas, the primary host species for the disease is poorly understood, and required a field study to determine the spatial distribution of T. cruzi prevalence in free-ranging mammals. Our study objectives were to determine the spatial distribution and prevalence of T. cruzi parasites in free-ranging mammals. We compared T. cruzi prevalence among species, among vegetative communities, and among different topographies (i.e., floodplain versus upland). From December 2011 through December 2013, 450 blood and tissue samples from geolocated free-ranging wildlife mammal species were analyzed with the use of polymerase chain reaction to detect protozoan T. cruzi DNA. We also calculated mammal abundance with the use of mark-recapture methodology and recorded capture-site characteristics such as vegetation structure. We found that animals in grasslands had a significantly lower infection rate when summed across all species compared with animals in dense hardwoods and semi-improved woodlands (P=0.001). A higher percentage of infections were found in the lower-elevation floodplain-65% (28/43) of animals sampled, compared to upland areas-25% (9/36) of animals sampled. Our study suggested that common free-ranging meso-mammals supported T. cruzi in natural environments and are of public health concern in South Texas. Mitigation strategies should consider a range of management activities to include vegetation management, selective application of insecticides, and changes in human behavior in high-risk areas.

Survey of raccoons on Key Largo, Florida, USA, for Baylisascaris procyonis.

Numbers of the endangered Key Largo woodrat (KLWR; Neotoma floridana smalli) have been declining for at least 25 yr. The raccoon (Procyon lotor) roundworm, Baylisascaris procyonis, has been found to have an adverse effect on the survival of Alleghany woodrats (N. magister). High densities of raccoons can exacerbate this problem by increasing the amount of feces containing viable eggs of B. procyonis available to woodrats. In 2002, 64 fecal samples were collected and examined for eggs of B. procyonis from >32 raccoons within the KLWR's known range on Key Largo, Florida, USA. All samples were negative for eggs of B. procyonis. Raccoon density in this area was approximately 0.62 raccoons/ha. Despite this high density of raccoons, B. procyonis does not appear to be a threat to the KLWR population.

Morbidity and mortality factors in key deer (Odocoileus virginianus clavium).

The population health of endangered Key deer (Odocoileus virginianus clavium) was monitored from 10 February 1986 to 28 September 2000 by necropsy of animals that were killed by vehicles, euthanized because of terminal injuries or disease conditions, or found dead. The predominant mortality factor during the period was collision with motor vehicles; however, several infectious diseases were diagnosed, including infections with Arcanobacterium pyogenes, Haemonchus contortus, Salmonella spp., and Mycobacterium avium subsp. paratuberculosis. During the period monitored, the only infectious disease that was thought to have affected population dynamics was haemonchosis. Nevertheless, several of the observed diseases have potential to impact viability of the Key deer population under appropriate environmental conditions.

Paratuberculosis in key deer (Odocoileus virginianus clavium).

Paratuberculosis was diagnosed in an endangered Key deer (Odocoileus virginianus clavium) in November 1996. Between 10 April 1997 and 28 September 2000, the Key deer population was monitored for infection with Mycobacterium avium subsp. paratuberculosis by necropsy of available carcasses (n = 170), fecal cultures, and serology. One additional clinically affected Key deer was discovered in July 1998, and M. avium subsp. paratuberculosis was cultured from the feces of one live, asymptomatic deer. The results of this study provided sufficient evidence to consider the Key deer herd infected with M. avium subsp. paratuberculosis at very low prevalence.

Predicting the impacts of future sea-level rise on an endangered lagomorph.

Human-induced global climate change presents a unique and difficult challenge to the conservation of biodiversity. Despite increasing attention on global climate change, few studies have assessed the projected impacts of sea-level rise to threatened and endangered species. Therefore, we estimated the impacts of rising sea levels on the endangered Lower Keys marsh rabbit (Sylvilagus palustris hefneri) across its geographic distribution under scenarios of current conditions, low (0.3-m), medium (0.6-m), and high (0.9-m) sea-level rise. We also investigated the impacts of allowing vegetation to migrate upslope and not allowing migration and of two land-use planning decisions (protection and abandonment of human-dominated areas). Not surprisingly, under all simulations we found a general trend of decreasing total potential LKMR habitat with increasing sea-level rise. Not allowing migration and protecting human-dominated areas both tended to decrease potential LKMR habitat compared with allowing migration and abandoning human-dominated areas. In conclusion, conservation strategies at multiple scales need to be implemented in order to reduce the impact of global climate change on biodiversity and endangered species. At the regional level, managers must consider land-use planning needs that take into account the needs of both humans and biodiversity. Finally, at the local scale those agencies that are in charge of endangered species conservation and ecosystem management need to rethink static approaches to conservation or else stand by and watch ecosystems degrade and species go extinct. This can be accomplished by bioclimatic reserve systems where climatically underrepresented areas are included in conservation planning along with the standard concerns of threat, opportunity, connectivity, and viability.