The long-term effects of sediment exposure on aquatic organisms are poorly understood, yet it is critical for determining threshold effects and exposure limits to mitigate potential impacts with regard to population dynamics. In this paper, we present the current state of knowledge to help consolidate the breadth of information regarding total suspended solids (TSS) thresholds for aquatic species, as well as identify areas where data are lacking. More specifically, we provide the state of the science related to TSS effects on freshwater and estuarine fish including short-term (i.e., physiology and behavior) and long-term effects. Our research indicated that little attention has been given to examining long-term effects, e.g., transgenerational effects, from suspended sediments (SS) on fish populations. Understanding transgenerational effects is paramount to developing and predicting the links between fish condition, survival, populations, and communities. Survival of a local fish population to high sediment loads often translates into short-term physiological and behavioral effects; however, the ramifications of such exposure events are rarely tracked across generations. The majority of studies involving SS effects on fish have focused on exposure and mortality rates of affected fish, deposited eggs, or larvae. We developed a conceptual model that highlighted the interactions between sediment dynamics and fish populations. The model can assist in the formulation of more quantitative-based approaches for modeling these interactions. Future research efforts should focus on developing an understanding of whether environmental disturbances, e.g., dredging, may lead to epigenetic changes that may lead to cascade population effects, and if so, under what circumstances.

Global estimates of the number of domestic cats (Felis catus) are >400 million. Issues associated with freeroaming cats are of global importance because of animal-welfare and public-health concerns and impacts on native wildlife through predation, competition and disease transmission. In the United States, proposed control solutions for managing urban free-roaming cat populations include euthanasia and trap-neuter-return (TNR) programs. We evaluated control methods using a demographic population model for a 25-year period, with parameters estimated from an unmanaged, free-roaming cat population in Texas. We modelled euthanasia and TNR at 25%, 50% and 75% implementation rates and a 50 : 50 combination of euthanasia and TNR at 25%, 50%, 75% and 100% implementation rates for 0%, 25% and 50% maximum immigration rates. We compared final population size, total number of cats treated and treatment effort relative to population reduction. Population decreases were comparable among euthanasia, TNR and a 50 : 50 combination for all treatment rates when the immigration rate was 0%; however, they were higher for euthanasia at 25% and 50% maximum immigration rates. Euthanasia required higher treatment effort than TNR. Our results indicate that immigration must be prevented and high (>50%) treatment rates implemented to reduce free-roaming cat populations.

Aim  We present an integrated approach for predicting future range expansion of an invasive species (Chinese tallow tree) that incorporates statistical forecasting and analytical techniques within a spatially explicit, agent‐based, simulation framework. Location  East Texas and Louisiana, USA. Methods  We drew upon extensive field data from the US Forest Service and the US Geological Survey to calculate spread rate from 2003 to 2008 and to parameterize logistic regression models estimating habitat quality for Chinese tallow within individual habitat cells. We applied the regression analyses to represent population spread rate as a function of habitat quality, integrated this function into a logistic model representing local spread, and coupled this model with a dispersal model based on a lognormal kernel within the simulation framework. We simulated invasions beginning in 2003 based on several different dispersal velocities and compared the resulting spatial patterns to those observed in 2008 using cross Mantel’s tests. We then used the best dispersal velocity to predict range expansion to the year 2023. Results  Chinese tallow invasion is more likely in low and flat areas adjacent to water bodies and roads, and less likely in mature forest stands and in pine plantations where artificial regeneration by planting seedlings is used. Forecasted invasions resulted in a distribution that extended from the Gulf Coast of Texas and Louisiana northward and westward as much as 300 km, representing approximately 1.58 million ha. Main conclusions  Our new approach of calculating time series projections of annual range expansion should assist land managers and restoration practitioners plan proactive management strategies and treatments. Also, as field sampling continues on the national array of FIA plots, these new data can be incorporated easily into the present model, as well as being used to develop and/or improve models of other invasive plant species.

Computer-assisted sperm analysis of fresh and frozen-thawed bovine sperm requires proper handling and preparation, and the type of slide used in the assessment is critical if the resultant data are to be useful quality control measurements. In the present study, 4 different slide viewing chambers, a Makler chamber, a clean slide-coverslip, or a 2- or 4-cell chamber Leja slide, were compared with assess their utility in providing reliable measurements of sperm motility variables. A Hamilton-Thorne IVOS Computer-Assisted Semen Analyzer (CASA) was the instrument used to determine sperm measurements utilizing the 4 different chambers. Fifty-eight different freeze batches of bovine semen that had been collected from 47 bulls at 7 sites that sex-sort sperm using Sexing Technologies sorting criteria were incorporated into the trial. Neither the percentage of motile sperm nor the percentage of progressively motile sperm differed for the Makler chamber vs. slide-coverslip comparisons. Similarly, total and progressively motile sperm did not differ between the 2- and 4-cell chambered Leja slides. However, total and progressive motility of sperm determined with the Makler chamber and slide-coverslip were greater (P< 0.0001) than motilities recorded by the 2- or 4-cell chambered Leja slides. Based on the results, the type of viewing chamber can affect the range of sperm motility values when CASA is used for quality control evaluations of thawed, cryopreserved sex-sorted sperm samples.

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Ecological models are important tools for planning ecosystem restoration and management activities. Models help to organize thinking, conceptualize understanding of complex systems, and forecast environmental benefits that may result from proposed restoration and management actions. This report provides information to guide environmental planers in selection, development, evaluation, and documentation of ecological models. A number of critical issues are addressed, including specifying objectives and formulating a sound conceptual model, choosing among types of models, deciding when to develop a new model, systematically evaluating the quantitative model, addressing parameter and model uncertainty, developing sections of the model through iteration, analyzing alternatives, and documenting results. Quantitative modeling is shown to be a dynamic process that is best served using an iterative approach. In practice, individual parts of a conceptual model are quantified and evaluated in a stepwise fashion until the entire model is captured quantitatively. This iterative approach creates transparency in model development, which can remove the "black-box" stigma that has been associated with the use of models in the environmental sciences.

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