Lantana: Current Management Status and Future Prospects

Crop Production/Industries,

Multiscale control of flooding and riparian‐forest composition in Lower Michigan, USA

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/117201/1/ecy2009901145.pd

Classifying Regional Variation in Thermal Regime Based on Stream Fish Community Patterns

Although the importance of water temperature to the ecology of stream fishes is well documented, relatively little information is available on the extent of regional variation in thermal regime and its influence on stream fish distribution and abundance patterns. In streams draining the heterogeneous glacial landscape of Michigan’s Lower Peninsula, regional variation in summer mean temperature and temperature fluctuation is among the highest reported in the literature. We developed a habitat classification to simplify the description of thermal regimes and to describe the relationships between available thermal regimes and distribution patterns of stream fishes. Changes in community composition, species richness, and standing stocks of key fish species occurred across gradients in mean temperature and temperature fluctuation. These changes were used to identify three mean temperature categories (cold, <19°C; cool, 19–<22°C; and warm, ≥22°C) and three temperature fluctuation categories (stable, <5°C; moderate, 5–<10°C; and extreme, ≥10°C). The combination of these categories resulted in a 3 × 3 matrix with nine discrete thermal regimes. The classification developed in this study provides a framework for descriptions of the realized thermal niche of stream fishes, and can be used as a baseline for measurement of changes in distribution patterns associated with future climate warming. Our results suggest that observed differences in community structure among sites are largely attributable to spatial variation in mean temperature and temperature fluctuation. Thus, accounting for the linkage between regional variation in thermal regime and fish community structure should improve our ability to effectively assess and manage stream resources.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141912/1/tafs0018.pd

Stimulating a Great Lakes Coastal Wetland Seed Bank using Portable Cofferdams: Implications for Habitat Rehabilitation

Coastal wetland seed banks exposed by low lake levels or through management actions fuel the reestablishment of emergent plant assemblages (i.e., wetland habitat) critical to Great Lakes aquatic biota. This project explored the effectiveness of using portable, water-filled cofferdams as a management tool to promote the natural growth of emergent vegetation from the seed bank in a Lake Erie coastal wetland. A series of dams stretching approximately 450 m was installed temporarily to isolate hydrologically a 10-ha corner of the Crane Creek wetland complex from Lake Erie. The test area was dewatered in 2004 to mimic a low-water year, and vegetation sampling characterized the wetland seed bank response at low, middle, and high elevations in areas open to and protected from bird and mammal herbivory. The nearly two-month drawdown stimulated a rapid seed-bank-driven response by 45 plant taxa. Herbivory had little effect on plant species richness, regardless of the location along an elevation gradient. Inundation contributed to the replacement of immature emergent plant species with submersed aquatic species after the dams failed and were removed prematurely. This study revealed a number of important issues that must be considered for effective long-term implementation of portable cofferdam technology to stimulate wetland seed banks, including duration of dewatering, product size, source of clean water, replacement of damaged dams, and regular maintenance. This technology is a potentially important tool in the arsenal used by resource managers seeking to rehabilitate the functions and values of Great Lakes coastal wetland habitats

Fish Assemblages, Connectivity, and Habitat Rehabilitation in a Diked Great Lakes Coastal Wetland Complex

Fish and plant assemblages in the highly modified Crane Creek coastal wetland complex of Lake Erie were sampled to characterize their spatial and seasonal patterns and to examine the implications of the hydrologic connection of diked wetland units to Lake Erie. Fyke netting captured 52 species and an abundance of fish in the Lake Erie–connected wetlands, but fewer than half of those species and much lower numbers and total masses of fish were captured in diked wetland units. Although all wetland units were immediately adjacent to Lake Erie, there were also pronounced differences in water quality and wetland vegetation between the hydrologically isolated and lake-connected wetlands. Large seasonal variations in fish assemblage composition and biomass were observed in connected wetland units but not in disconnected units. Reestablishment of hydrologic connectivity in diked wetland units would allow coastal Lake Erie fish to use these vegetated habitats seasonally, although connectivity does appear to pose some risks, such as the expansion of invasive plants and localized reductions in water quality. Periodic isolation and drawdown of the diked units could still be used to mimic intermediate levels of disturbance and manage invasive wetland vegetation

Towards a Process Domain‐Sensitive Substrate Habitat Model for Sea Lampreys in Michigan Rivers

Habitat mapping is a common and often useful tool in the ecological management of rivers. The complex nature of fluvial processes, however, makes it difficult to predict the reach‐scale distribution of substrate habitat from landscape‐scale covariates. An option is to identify and partition a data set on boundaries of geomorphic process domains, within which the globally complex relationships between landscape, climate, and instream habitat may potentially be approximated by a simpler model. In this study, we used regression trees as a machine learning method for partitioning and identifying useful strata in a geographically extensive substrate habitat model for larvae of the sea lamprey Petromyzon marinus, an invasive and economically harmful species in the Laurentian Great Lakes. We used field survey data from over 5,000 substrate habitat transects collected in 43 watersheds of the Lower Peninsula of Michigan, and we created a geographic database of geographical information systems‐derived covariates that represent the principal geomorphic influences on substrate habitat. We created three trees in which tree splits delineated (1) spatially contiguous units, (2) noncontiguous units defined by values of the covariates, and (3) both contiguous and noncontiguous units. The adjusted R2 values of the three trees were 0.30, 0.30, and 0.32, respectively, and all three trees outperformed a single model fitted to the entire data set and a set of models fitted to each watershed individually. The trees identified useful stratifications of Michigan’s Lower Peninsula, important geomorphic influences on substrate habitat, and variation in the influence of geomorphic processes on substrate habitat across our study region. Conservation and management applications of our model predictions and tree‐based stratifications include sea lamprey population modeling, habitat survey design, and evaluation of dam removal.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141668/1/tafs0313.pd

Study Methodology

Data for this investigation come from 36 qualitative in-depth interviews completed between February and April 2010. The aim of the research was to conduct a process evaluation of Gateway Foundation programming for state probation and parole clients in St. Louis and jointly produce a final report for the organization. The specific research questions focused on (1) the challenges men face as they attempt to overcome substance abuse; (2) how those challenges are related to past experiences with crime, including offending and victimization; and (3) the effectiveness of Gateway programming, from the points of view of program participants, including whether there are any perceived differences between men who participate in the program post-incarceration versus in lieu of incarceration

Translation Initiation Rate Determines the Impact of Ribosome Stalling on Bacterial Protein Synthesis

Ribosome stalling during translation can be caused by a number of characterized mechanisms. However, the impact of elongation stalls on protein levels is variable, and the reasons for this are often unclear. To investigate this relationship, we examined the bacterial translation elongation factor P (EF-P), which plays a critical role in rescuing ribosomes stalled at specific amino acid sequences including polyproline motifs. In previous proteomic analyses of both Salmonella and Escherichia coli efp mutants, it was evident that not all proteins containing a polyproline motif were dependent on EF-P for efficient expression in vivo . The α- and β-subunits of ATP synthase, AtpA and AtpD, are translated from the same mRNA transcript, and both contain a PPG motif; however, proteomic analysis revealed that AtpD levels are strongly dependent on EF-P, whereas AtpA levels are independent of EF-P. Using these model proteins, we systematically determined that EF-P dependence is strongly influenced by elements in the 5′-untranslated region of the mRNA. By mutating either the Shine-Dalgarno sequence or the start codon, we find that EF-P dependence correlates directly with the rate of translation initiation where strongly expressed proteins show the greatest dependence on EF-P. Our findings demonstrate that polyproline-induced stalls exert a net effect on protein levels only if they limit translation significantly more than initiation. This model can be generalized to explain why sequences that induce pauses in translation elongation to, for example, facilitate folding do not necessarily exact a penalty on the overall production of the protein

Changes in the arctic ocean carbon cycle with diminishing ice cover

© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in DeGrandpre, M., Evans, W., Timmermans, M., Krishfield, R., Williams, B., & Steele, M. Changes in the arctic ocean carbon cycle with diminishing ice cover. Geophysical Research Letters, 47(12), (2020): e2020GL088051, doi:10.1029/2020GL088051.Less than three decades ago only a small fraction of the Arctic Ocean (AO) was ice free and then only for short periods. The ice cover kept sea surface pCO2 at levels lower relative to other ocean basins that have been exposed year round to ever increasing atmospheric levels. In this study, we evaluate sea surface pCO2 measurements collected over a 6‐year period along a fixed cruise track in the Canada Basin. The measurements show that mean pCO2 levels are significantly higher during low ice years. The pCO2 increase is likely driven by ocean surface heating and uptake of atmospheric CO2 with large interannual variability in the contributions of these processes. These findings suggest that increased ice‐free periods will further increase sea surface pCO2, reducing the Canada Basin's current role as a net sink of atmospheric CO2.This research was made possible by grants from the NSF Arctic Observing Network program (ARC‐1107346, PLR‐1302884, PLR‐1504410, and OPP‐1723308). In addition, M. S. was supported by ONR (Grant 00014‐17‐1‐2545), NASA (Grant NNX16AK43G), and NSF (Grants PLR‐1503298 and OPP‐1751363)

Structural Analysis and Testing of the Inflatable Re-entry Vehicle Experiment (IRVE)

The Inflatable Re-entry Vehicle Experiment (IRVE) is a 3.0 meter, 60 degree half-angle sphere cone, inflatable aeroshell experiment designed to demonstrate various aspects of inflatable technology during Earth re-entry. IRVE will be launched on a Terrier-Improved Orion sounding rocket from NASA s Wallops Flight Facility in the fall of 2006 to an altitude of approximately 164 kilometers and re-enter the Earth s atmosphere. The experiment will demonstrate exo-atmospheric inflation, inflatable structure leak performance throughout the flight regime, structural integrity under aerodynamic pressure and associated deceleration loads, thermal protection system performance, and aerodynamic stability. Structural integrity and dynamic response of the inflatable will be monitored with photogrammetric measurements of the leeward side of the aeroshell during flight. Aerodynamic stability and drag performance will be verified with on-board inertial measurements and radar tracking from multiple ground radar stations. In addition to demonstrating inflatable technology, IRVE will help validate structural, aerothermal, and trajectory modeling and analysis techniques for the inflatable aeroshell system. This paper discusses the structural analysis and testing of the IRVE inflatable structure. Equations are presented for calculating fabric loads in sphere cone aeroshells, and finite element results are presented which validate the equations. Fabric material properties and testing are discussed along with aeroshell fabrication techniques. Stiffness and dynamics tests conducted on a small-scale development unit and a full-scale prototype unit are presented along with correlated finite element models to predict the in-flight fundamental mo