On the resonance of a pliant tube as a mechanism for valveless pumping

Valveless pumping can be achieved through the periodic compression of a pliant tube asymmetrically from its interfaces to different tubing or reservoirs. A mismatch of characteristic impedance between the flow channels is necessary for creating wave reflection sites. Previous experimental studies of the behaviour of such a pump were continued in order to demonstrate the wave mechanics necessary for the build-up of pressure and net flow. Specific measurements of the transient and resonant properties were used to relate the bulk responses to the pump mechanics. Ultrasound imaging through the tube wall allowed visualization of the wall motion concurrently with pressure and flow measurements. For analysis, a one-dimensional wave model was constructed which predicted many of the characteristics exhibited by the experiments

Interactions Among Top-down Regulators in a Temperate Forest Floor Ecosystem;Effects on Macrofauna, Mesofauna, Microbes and Litter Decay

High species diversity and complexity of forest-floor food webs present a challenge for understanding the role of species interactions (e.g. competition and predation) as regulatory mechanisms for ecosystem processes such as decomposition and nutrient cycling. In particular, we understand very little about the roles of forest-floor predators in regulating diversity and abundance of lower trophic levels and ecosystem processes. However, ecological theory and several studies suggest that interactions among intraguild predators (IGP) may be important controls of diversity and abundance of organisms and detritus in lower trophic levels within food webs. A key prediction is that interactions among predators weaken trophic cascades. My research examined this prediction by characterizing interactions among predators and examining their effects on lower trophic levels within the forest-floor food web of Northeast Ohio. The results of the laboratory microcosm studies, in combination with several previous studies, suggest that the effects of removal treatment on intraguild predators, especially centipedes, spiders, carabid beetles, and salamander, were not the result of intraguild predation, but were more likely to have been the result of non-consumptive competitive interactions (NCEs). Predator removal from open, unrestricted field plots resulted in changes in the abundances of several groups of predators and macrodetritivores. Additionally, I found that predator manipulation affected composition of microflora within the soils at my field site. The mechanisms for this effect remain uncertain but may be indicative of antibiotic interactions within the soil through bacteria dispersed through skin secretions and feces of predators, particularly salamanders. This work contributes significantly to a growing body of evidence indicating that territorial predators, such as P. cinereus, which are constrained to spatially fixed microhabitats, can be strong regulators of guild members and lower trophic levels. My results also supp

Behavioral interactions between terrestrial salamanders and spiders: competition or intraguild predation? Behavioral interactions between terrestrial salamanders and spiders: competition or intraguild predation?

Several studies suggest that small terrestrial salamanders are important regulators of leaf litter arthropod communities, and likely contribute to ecosystem processes such as decomposition and nutrient cycling. Despite the recognition that salamanders have the potential to strongly affect ecosystem function through both direct and indirect pathways, little is known regarding the nature of interactions between small vertebrates and the large, predatory arthropods with which they share both microhabitat and prey. Our study was designed to explore interactions between Eastern Red-backed Salamanders, Plethodon cinereus, and spiders in the genus Wadotes in an eastern North American temperate forest ecosystem. We were particularly interested in teasing apart behaviors such as territoriality and intraguild predation in an attempt to determine specifically which interaction is most likely responsible for the observed negative relationship between salamander and spider abundance at our field site. Field data indicate that P. cinereus and large syntopic spiders exhibit negative spatial associations in the microhabitat beneath cover objects, a possible indication of interspecific territoriality. In our laboratory experiments, resident salamanders displayed agonistic postures similarly toward both intruding conspecifics and spiders, suggesting that salamanders may perceive large intruding spiders as competitors. Finally, we observed no injuries to individual P. cinereus or adult spiders even though occasional chases and bites by both were recorded during the behavioral trials. We found no evidence that adults or juveniles of P. cinereus were envenomated by adult Wadotes spp., and there were no instances of intra-guild predation in this study. Multiple lines of evidence from this study, and others, suggest that the primary interaction between individuals of P. cinereus and large spiders is competitive in nature rather than predatory. We suggest that the cost associated with intraguild predation on salamanders with noxious skin secretions may preclude them from being preyed upon by spiders

Competition and Intraguild Predation Between Beetles, Pterostichus stygicus (Coleoptera: Carabidae) and Centipedes, Scolopocryptops sexspinosus (Scolopemdromorpha: Scolopocryptopidae)

Studying interactions between distantly related species is necessary to understand the complexity of food webs. Generalist predator interactions, such as intraguild predation (IGP) and competition, can alleviate predation pressure and weaken top–down control that predators have on lower trophic levels. Centipedes (Chilopoda) and carabid beetles (Coleoptera) are common deciduous forest floor generalist predators that may interact by competing for resources beneath rocks and logs on the forest floor, especially during dry periods when prey become confined to such microhabitats. We used laboratory and field studies to determine whether the carabid beetle, Pterostichus stygicus (Say), and the centipede, Scolopocryptops sexspinosus (Say) co-occur under artificial cover. Additionally, a laboratory mesocosm experiment was used to examine competi- tive interactions in intra- and interspecific trials. There was significant negative co-occurrence of beetles and centipedes beneath cover objects in the field and laboratory. Pairings of S. sexspinosus and P. stygicus within mesocosms resulted in high mortality of P. stygicus, and reciprocal but asymmetric IGP. Centipedes maintained weight within solitary, intra- and interspecific mesocosm treatments, however, beetles lost mass in all treat- ments. Scolopocryptops sexspinosus responded more favorably to intra- and interspecific competition than did P. stygicus. Analysis of the leaf litter mesofauna indicated that these predators consumed similar prey in laboratory mesocosms. Our results suggest that species with very different trophic morphology have the po- tential to compete for shared microhabitat and prey

Black Corals of the Flower Garden Banks National Marine Sanctuary

Black corals (Cnidaria: Anthozoa: Antipatharia) of the Flower Garden Banks National Marine Sanctuary (FGBNMS) are described. A key to the species is provided and supplemented with in situ and laboratory photos. The microscopic skeletal features of the species are illustrated from photographs taken with a scanning electron microscope. Thirteen species of black corals are found in the FGBNMS, belonging to the families Antipathidae (Antipathes furcata Gray 1857; Antipathes atlantica Gray 1857, Stichopathes luetkeni Brook 1889; Stichopathes pourtalesi Brook 1889, and Stichopathes sp.); Aphanipathidae [Aphanipathes pedata (Gray 1857), Elatopathes abietina (Pourtalès 1874), Acanthopathes thyoides (Pourtalès 1880) and Phanopathes expansa (Opresko and Cairns 1992)]; and Myriopathidae [Plumapathes pennacea (Pallas 1766), Tanacetipathes tanacetum (Pourtalès 1880), Tanacetipathes hirta (Gray 1857), and Tanacetipathes cf. thamnea (Warner 1981)]

Eastern Red-backed Salamanders Regulate Top-Down Effects in a Temperate Forest-Floor Community

Understanding the role of species interactions as regulatory mechanisms for ecosystem processes presents a challenge to ecologists working in systems with high species diversity and habitat complexity. Recent studies suggest that interactions among intraguild predators, such as terrestrial salamanders and large arthropods, might be important for the regulation of detritivores, fungivores, and perhaps detritus within terrestrial webs. A key prediction is that interactions among predators weaken trophic cascades. Our research examined this prediction by removing predators for 4 yr from unfenced field plots to investigate the effects on litter arthropods, the microbial community, and rates of leaf litter decomposition. We manipulated predator abundance in three treatments (salamander removal, centipede removal, and multiple predator removal) compared to a control in which no predators were removed. Despite difficulties in suppressing centipede numbers, we observed increases in salamanders, millipedes, isopods, slugs, numbers of ant colonies, and gamasid mites in the centipede removal plots. Additionally, several phospholipid fatty acid markers for bacteria were suppressed in plots where salamanders were most abundant. Finally, we detected treatment effects on the rate of litter disappearance from leaf bags in our field plots: those with the most salamanders had the lowest levels of litter decomposition. Overall, we found some evidence for top-down effects of predators in a temperate forest-floor web. Our study is one of few that have employed an unfenced field design and the only study examining the effects of salamanders on forest soil microbes. The results contribute to a growing body of evidence indicating that territorial predators, such as terrestrial salamanders, can be strong regulators of species composition at lower trophic levels in a system that is commonly thought to be regulated primarily through bottom-up effects of organic matter supply

Validation of Image-Based Species Identifications of Black Corals (Order Antipatharia) on Mesophotic Rocks

Biodiversity, an important measure of ecosystem health, is challenging to ascertain using sampled specimens in remote deep-sea environments. As image-based identifications become a predominant method for deep-sea species characterizations, there is a need to evaluate the accuracy of species- and genus-level identifications from video and still images to provide a reliable measure of biodiversity. This study presents a validation of the ability to make accurate image-based identifications of black coral species in the northwestern Gulf of Mexico from standard-definition video collected by a remotely operated vehicle. Results indicate that the greatest number of misidentifications occurred at species-level groupings (42.2% error), whereas genus-level groupings possessed 12.0% error, and identifications to kappa groupings had no error. We recommend genus-level groupings to maintain accurate identifications while maximizing estimates of biodiversity

Ramanujan's 1ψ1_{1}\psi_1 summation, Hecke-type double sums, and Appell-Lerch sums

We use a specialization of Ramanujan's ${}_1\psi_1$ summation to give a new proof of a recent formula of Hickerson and Mortenson which expands a special family of Hecke-type double sums in terms of Appell-Lerch sums and theta functions.Comment: Identity $(2.2)$ was known to L. Kronecke