A Case for Using Plethodontid Salamanders for Monitoring Biodiversity and Ecosystem Integrity of North American Forests

Abstract: Terrestrial salamanders of the family Plethodontidae have unique attributes that make them excellent indicators of biodiversity and ecosystem integrity in forested habitats. Their longevity, small territory size, site fidelity, sensitivity to natural and anthropogenic perturbations, tendency to occur in high densities, and low sampling costs mean that counts of plethodontid salamanders provide numerous advantages over counts of other North American forest organisms for indicating environmental change. Furthermore, they are tightly linked physiologically to microclimatic and successional processes that influence the distribution and abundance of numerous other hydrophilic but difficult-to-study forest-dwelling plants and animals. Ecosystem processes such as moisture cycling, food-web dynamics, and succession, with their related structural and microclimatic variability, all affect forest biodiversity and have been shown to affect salamander populations as well. We determined the variability associated with sampling for plethodontid salamanders by estimating the coefficient of variation (CV ) from available time-series data. The median coefficient of variation indicated that variation in counts of individuals among studies was much lower in plethodontids (27%) than in lepidoptera (93%), passerine birds (57%), small mammals (69%), or other amphibians (37–46%), which means plethodontid salamanders provide an important statistical advantage over other species for monitoring long-term forest health.     

Assessing Multiregion Avian Benefits from Strategically Targeted Agricultural Buffers

Mounting evidence of wildlife population gains from targeted conservation practices has prompted the need to develop and evaluate practices that are integrated into production agriculture systems and targeted toward specific habitat objectives. However, effectiveness of targeted conservation actions across broader landscapes is poorly understood. We evaluated multiregion, multispecies avian densities on row‐crop fields with native grass field margins (i.e., buffers) as part of the first U.S. agricultural conservation practice designed to support habitat and population recovery objectives of a national wildlife conservation initiative. We coordinated breeding season point transect surveys for 6 grassland bird species on 1151 row‐crop fields with and without native grass buffers (9–37 m) in 14 U.S. states (10 ecoregions) from 2006 to 2011. In most regions, breeding season densities of 5 of 6 targeted bird species were greater in the 500‐m surrounding survey points centered on fields with native grass buffers than in landscapes without buffers. Relative effect sizes were greatest for Northern Bobwhite (Colinus virginianus), Dickcissel (Spiza americana), and Field Sparrow (Spizella pusilla) in the Mississippi Alluvial Valley and Eastern Tallgrass Prairie regions. Other species (e.g., Eastern Meadowlark [Sturnella magna], Grasshopper Sparrow [Ammodramus savannarum]) exhibited inconsistent relative effect sizes. Bird densities on fields with and without buffers were greatest in the Central Mixed‐grass Prairie region. Our results suggest that strategic use of conservation buffers in regions with the greatest potential for relative density increases in target species will elicit greater range‐wide population response than diffuse, uninformed, and broadly distributed implementation of buffers. We recommend integrating multiple conservation practices in broader agricultural landscapes to maximize conservation effectiveness for a larger suite of species. Evaluación de los Beneficios de la Mutliregionalidad de Aves a Partir de Amortiguadores Agriculturales Estratégicamente Señalados     

Morphology and distribution of the ampullary electroreceptors in wobbegong sharks: implications for feeding behaviour

The electrosensory capabilities of wobbegong sharks are of particular interest, partly because very little is known about their behavioural ecology and specifically because of their unusual ambush predatory strategy and benthic lifestyle. While several biological functions of electroreception have been proposed, less consideration has been given to the functional significance of interspecific differences in the morphology and topographic distribution of the ampullary organs. The morphology of the ampullary organs was examined in four species of wobbegong shark, and the distribution of electroreceptive pores was mapped in two species. The ampullary systems of wobbegongs are similar in morphology to other marine elasmobranchs. The number of alveoli per ampullae is not significantly different between the four species; however, differences are seen between ampullary cell size in some species. Ampullary pore distribution patterns are relatively unique, with the majority of pores occurring on the dorsal region of the head. Wobbegongs feed primarily on demersal teleost fishes, and as the benthic and well-camouflaged wobbegong remains motionless, these fish could be easily detected by the dorsal pores when swimming within range.     

Testing the effectiveness of capture mark recapture population estimation techniques using a computer simulation with known population size

Estimation of small mammal population sizes is important for monitoring ecosystem condition and for conservation. Here, we test the accuracy of standard methods of population size estimation using Capture-Mark-Recapture (CMR) on a simulated population of agents. The use of a computer simulation allows complete control of population sizes and behaviors, thereby avoiding assumptions that may be violated in real populations. We find that the recommended protocol for CMR sampling, using uniformly distributed traps, consistently overestimates population sizes by as much as 100% when studies are conducted over only two trapping periods. More than 20 trapping periods are required before this method, or that of placing traps randomly, gives an accurate estimation of population size (i.e., within a 95% confidence limit of the actual value). Non-random sampling, by placing traps on runways used by small mammals, produces the most accurate, and least variable, estimates of population. However, we show that around 10 trapping periods are still required to produce an accurate population estimate using this method. Given that most real populations do not comply with the ‘ideal’ assumptions made by CMR, we suggest that population estimates based on CMR may be fundamentally flawed, and recommend that protocols for CMR population estimation methods may need revising.     

Comparing Contaminant Removal Costs for Aquifer Recharge with Wastewater with Water Supply Benefits

The use of waters of impaired quality has been suggested as a means to expand available water resources supply for water‐limited communities. An ongoing concern is the safety of supplies that use wastewater because of the potential for introduction of emerging contaminants such as pharmaceuticals into drinking water supplies. Prior research into contaminants of emerging concerns (CECs) have included a variety of methods, but the only consistent removal is with reverse osmosis (RO) membranes, ultraviolet light (UV), and advanced oxidation processes (AOP). However, few of these prior studies have measurable quantities of these contaminants in the influent wastewater, so determining actual removal percentages is difficult. This project was designed to evaluate the removal of CECs to verify that a 3‐log removal of common constituents was realized. Spike testing was used to compare to prior research and to evaluate whether the project costs were competitive with other forms of reuse or other water supplies. The combination of RO/UV/AOP was effective at obtaining a 3‐log removal of CECs, but the RO and UV/AOP processes alone were not capable of removing all substances. However, despite the extensive treatment, the proposed process was both competitive cost‐wise and met the water quality goals.     

Ecological Benefits of Riparian Reforestation in Urban Watersheds: Study Design and Preliminary Results

Riparian forest restoration has become a major focus of watershed initiatives to improve degraded stream ecosystems. In urban watersheds, however, the ability of riparian forests to improve stream ecosystems may be diminished due to widespread, upland disturbance. This paper presents the methodology and some preliminary results from the first year of fieldwork on a 3-year project designed to assess the ecological benefits of riparian reforestation in urban watersheds. The study is based on an integrated, multidisciplinary sampling of physical, chemical, and biological attributes at forested and non-forested sections of 12 streams with different amounts of urban developement within their watersheds. Restored sections of three streams are also being monitored over the 3-year duration of the project. Sampling and analysis will continue through December 2000.     

Do Indicators Help Create Sustainable Communities?

Sustainability is becoming an increasing concern among communities across the United States. In response, a growing number of grassroots and public sector groups are initiating efforts to simultaneously address environmental, economic, and social issues, increase community well-being, and secure the long-term health of human and natural systems. Since 1990, dozens, if not hundreds, of sustainable communities projects have been initiated in cities, counties, and regions across the country. Collectively termed the 'sustainable communities movement', these efforts share much in common with a number of other 'community movements' including healthy communities movement and quality of life movement.