Department of Fish and Wildlife Conservation

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Browsing Department of Fish and Wildlife Conservation by Department "Biological Sciences"

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    Does Stream Size Really Explain Biodiversity Patterns in Lotic Systems? A Call for Mechanistic Explanations
    Vander Vorste, Ross; McElmurray, Philip; Bell, Spencer; Eliason, Kevin M.; Brown, Bryan L. (MDPI, 2017-07-08)
    Understanding drivers of biodiversity is a long-standing goal of basic and applied ecological research. In riverine systems, there remains a critical need to identify these drivers as efforts to manage and protect rivers grow increasingly desperate in the face of global change. We explored one commonly cited potential driver of riverine biodiversity, stream size (e.g., stream order, watershed area, width), using a systematic literature review paired with an analysis of broad-scale macroinvertebrate and fish communities. Of the 165 papers reviewed, we found mostly positive, but no universal, relationship between biodiversity and stream size despite inconsistent use of over 30 measures of stream size. One-third of studies failed to report explanatory mechanisms driving biodiversity–stream size relationships. Across over 4000 macroinvertebrate and fish samples from 1st–8th order streams in the contiguous USA, our analysis showed biodiversity (Shannon diversity, functional diversity, beta diversity) generally increased with measures of stream size. However, because of inconsistent and generally weak relationships between biodiversity and stream size across organismal groups, we emphasize the need to look beyond simple physical stream size measures to understand and predict riverine biodiversity, and strongly suggest that studies search for more mechanistic explanations of biodiversity patterns in lotic systems.
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    Exposure to residual concentrations of elements from a remediated coal fly ash spill does not adversely influence stress and immune responses of nestling tree swallows
    Beck, Michelle L.; Hopkins, William A.; Hallagan, John J.; Jackson, Brian P.; Hawley, Dana M. (Oxford University Press, 2014)
    Anthropogenic activities often produce pollutants that can affect the physiology, growth and reproductive success of wildlife. Many metals and trace elements play important roles in physiological processes, and exposure to even moderately elevated concentrations of essential and non-essential elements could have subtle effects on physiology, particularly during development. We examined the effects of exposure to a number of elements from a coal fly ash spill that occurred in December 2008 and has since been remediated on the stress and immune responses of nestling tree swallows. We found that nestlings at the site of the spill had significantly greater blood concentrations of Cu, Hg, Se and Zn in 2011, but greater concentrations only of Se in 2012, in comparison to reference colonies. The concentrations of elements were below levels of significant toxicological concern in both years. In 2011, we found no relationship between exposure to elements associated with the spill and basal or stress-induced corticosterone concentrations in nestlings. In 2012, we found that Se exposure was not associated with cellmediated immunity based on the response to phytohaemagglutinin injection. However, the bactericidal capacity of nestling plasma had a positive but weak association with blood Se concentrations, and this association was stronger at the spill site. Our results indicate that exposure to these low concentrations of elements had few effects on nestling endocrine and immune physiology. The long-term health consequences of low-level exposure to elements and of exposure to greater element concentrations in avian species require additional study.
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    Gray-bellied Hawk (Accipiter Poliogaster) Observed Feeding on a Tinamou in Yasuni Biosphere Reserve, Ecuador
    Melnyk, Kimberley; Gelis, Rudy A.; Hopkins, William A.; Vaca, Fernando; Moore, Ignacio T. (Raptor Research Foundation, 2013)
    The Gray-bellied Hawk (Accipiter poliogaster) is one of the least studied birds of prey in the neotropics. Its geographical range in South America is from northern Colombia, east to southern Venezuela and the Guianas, south to northeastern Ecuador, eastern Peru, Amazonian and southeastern Brazil, northern Bolivia, southeastern Paraguay and northeastern Argentina (Jenkinson and Tuttle 1976, Ridgely and Greenfield 2001, Thiollay 2007, Global Raptor Information Network 2012). Despite a lack of information regarding its movements, the Gray-bellied Hawk is thought to be a permanent resident in Ecuador due to year-round sightings of the species (Ridgely and Greenfield 2001, Global Raptor Information Network 2012).
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    High levels of maternally transferred mercury disrupt magnetic responses of snapping turtle hatchlings (Chelydra serpentina).
    Phillips, John B.; Landler, Lukas (2017-09-30)
    The Earth's magnetic field is involved in spatial behaviours ranging from long-distance migration to nongoal directed behaviours, such as spontaneous magnetic alignment (SMA). Mercury is a harmful pollutant most often generated from anthropogenic sources that can bio-accumulate in animal tissue over a lifetime.We compared SMA of hatchling snapping turtles from mothers captured at reference (i.e., low mercury) and mercury contaminated sites. Reference turtles showed radio frequency-dependent SMA along the north-south axis, consistent with previous studies of SMA, while turtles with high levels of maternally inherited mercury failed to show consistent magnetic alignment. In contrast, there was no difference between reference and mercury exposed turtles on standard performance measures. The magnetic field plays an important role in animal orientation behaviour and may also help to integrate spatial information from a variety of sensory modalities. As a consequence, mercury may compromise the performance of turtles in a wide variety of spatial tasks. Future research is needed to determine the threshold for mercury effects on snapping turtles, whether mercury exposure compromises spatial behaviour of adult turtles, and whether mercury has a direct effect on the magnetoreception mechanism(s) that mediate SMA or a more general effect on the nervous system.
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    Moderate echinostoma trivolvis infection has no effects on physiology and fitness-related traits of larval pickerel frogs (rana palustris)
    Orlofske, Sarah A.; Belden, Lisa K.; Hopkins, William A. (American Society of Parasitology, 2009-08)
    High intensity infections of Echinostoma trivolvis is metacercariae decrease survival and growth of young amphibian larvae. However, in nature, parasites are highly aggregated, which results in a large proportion of the amphibian population being only moderately infected. Survival and growth responses at these more-common, low-infection levels remain poorly studied. Thus, we investigated the effects of moderate Echinostoma trivolvis metacercariae infection (following exposure to 0, 10, 30, or 90 cercariae) on the growth and development of pickerel frog (Rana palustris) tadpoles. We measured metabolism to determine whether increased energy expenditure is a potential physiological mechanism underlying previously documented reduced growth. Furthermore, we quantified tadpole intestine size, which can exhibit plasticity in response to changing metabolic demands, and we characterized metacercariae distribution in tadpole kidneys. Metacercariae encysted in the pronephros significantly more than in the mesonephros, but tended to occur equally in right and left kidneys. Two mo post-infection (PI), there were no changes in tadpole survival, development, intestine size, or growth related to metacercariae infection. Similarly, metacercariae did not significantly increase metabolic rates during encystment or at I mo PI. Our study demonstrated that modest E. trivolvis infections, representative of a large proportion of the host population, had no detectable effects on fitness-related traits in laboratory isolation from other ecological variables.
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    A new composite abundance metric detects stream fish declines and community homogenization during six decades of invasions
    Sleezer, Logan J.; Angermeier, Paul L.; Frimpong, Emmanuel A.; Brown, Bryan L. (Wiley, 2021-08-10)
    Aim We developed a new technique, utilizing species-specific counts of individuals from historical fish community samples, to examine landscape-level, spatio-temporal trends in relative abundance distributions. Abundance-based historical distribution analyses are often plagued by data comparability issues, but provide critical information about community composition trends inaccessible to those using analyses based only on species presence–absence. We established trends in native and non-native fish abundance and community homogenization, uniqueness and diversity to help local conservation managers prioritize targets and motivate similar studies globally to support fish conservation. Location Upper and middle New River (UMNR) basin, Appalachian Mountains, USA. Methods We compiled catch data from 61 years of fish community surveys (1958–2019) and tested for community homogenization by comparing data from repeatedly sampled sites (1900s versus 2000s samples) using dispersion analyses. We measured community uniqueness (site contributions to beta diversity) and species diversity (Shannon index) at sampled streams to identify potential conservation hotspots. We then used regression analyses and Wilcoxon signed-rank tests to examine species-specific basin-wide and local abundance trends and identify species of potential conservation concern. Results Dispersion of sites in species abundance space was significantly greater in the 1900s compared with the 2000s, indicating homogenization had occurred. Of 36 native species analysed, 44.4% (16) showed basin-wide declines. Non-native species exhibited mixed patterns; site-level abundance increased in 2 of 15 species analysed (13%). Main conclusions Our results indicate basin-wide community homogenization has occurred within the UMNR, but many unique and diverse communities persist. If conserved, these could help maintain regional fish diversity. We found basin-wide declines in four endemic species, as well as spread patterns of non-native and native species that were not detected by a presence–absence analysis applied within the same study area. This finding illustrates the importance of considering both species’ abundance and occurrence patterns as separate dimensions of biodiversity to inform conservation planning.
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    Observations at backyard bird feeders influence the emotions and actions of people that feed birds
    Dayer, Ashley A.; Rosenblatt, Connor; Bonter, David N.; Faulkner, Holly; Hall, Richard J.; Hochachka, Wesley M.; Phillips, Tina B.; Hawley, Dana M. (British Ecological Society, 2019-03-25)
    1. Backyard bird feeding is one of the most common ways people engage with wildlife in many parts of the world. Given its scale, it can have profound consequences for the ecology of feeder birds and their behaviour. While previous work has primarily explored socio‐demographic factors associated with bird feeding, how observations of nature at backyard feeders (e.g. changes in feeder bird abundance, interaction with natural enemies and weather) influence people's propensity to feed birds remain largely unknown. 2. We examined the association between peoples’ observations at their backyard feeders and their emotions and behaviours related to providing food to birds. We conducted an online survey of a subset of United States participants in Project FeederWatch, a large‐scale citizen science project. 3. Overwhelmingly, respondents (n = 1,176) reported taking actions, such as managing predators or maintaining feeders, in response to observable natural factors (e.g. increased incidence of disease, the presence of predators, increased bird abundance). Additionally, respondents described a variety of emotional responses to the scenarios of depredation or disease at their feeders, some of which (particularly anger) had a small association with whether a respondent would take action in response. Respondents generally believed that their bird feeding benefits backyard birds (e.g. by improving overwinter survival and overall health), and indicated that natural factors (e.g. bird abundance, disease prevalence) and abiotic factors (i.e. cold temperature) had more of an influence on how much they feed birds than internal constraints such as time and money. 4. These findings suggest that human behaviour with respect to bird feeding is coupled to observations of nature, which could lead to feedbacks between provisioning intensity and ecological dynamics. Overall, our results have important implications for bird conservation and for understanding the potential benefits that humans receive from provisioning birds.
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    Spontaneous Magnetic Alignment by Yearling Snapping Turtles: Rapid Association of Radio Frequency Dependent Pattern of Magnetic Input with Novel Surroundings
    Landler, Lukas; Painter, Michael Scott; Youmans, Paul W.; Hopkins, William A.; Phillips, John B. (PLOS, 2015-05-15)
    We investigated spontaneous magnetic alignment (SMA) by juvenile snapping turtles using exposure to low-level radio frequency (RF) fields at the Larmor frequency to help characterize the underlying sensory mechanism. Turtles, first introduced to the testing environment without the presence of RF aligned consistently towards magnetic north when subsequent magnetic testing conditions were also free of RF (‘RF off → RF off’), but were disoriented when subsequently exposed to RF (‘RF off → RF on’). In contrast, animals initially introduced to the testing environment with RF present were disoriented when tested without RF (‘RF on → RF off’), but aligned towards magnetic south when tested with RF (‘RF on → RF on’). Sensitivity of the SMA response of yearling turtles to RF is consistent with the involvement of a radical pair mechanism. Furthermore, the effect of RF appears to result from a change in the pattern of magnetic input, rather than elimination of magnetic input altogether, as proposed to explain similar effects in other systems/organisms. The findings show that turtles first exposed to a novel environment form a lasting association between the pattern of magnetic input and their surroundings. However, under natural conditions turtles would never experience a change in the pattern of magnetic input. Therefore, if turtles form a similar association of magnetic cues with the surroundings each time they encounter unfamiliar habitat, as seems likely, the same pattern of magnetic input would be associated with multiple sites/localities. This would be expected from a sensory input that functions as a global reference frame, helping to place multiple locales (i.e., multiple local landmark arrays) into register to form a global map of familiar space.