Interactions between cover crops and weed management in Iowa\u27s conventional cropping systems

The effect of different levels of cereal rye (Secale cereale L.) residue on common waterhemp (Amaranthus rudis Sauer) and common lambsquarters (Chenopodium album L.) emergence was determined. Cereal rye seeding date had a greater effect on rye biomass accumulation and percent cover than seeding rate. Common waterhemp emergence was equal to or increased in the presence of cereal rye residue in both 2013 and 2014 compared to the control. Common lambsquarters emergence was increased in two treatments in 2014 but was otherwise unaffected by cereal rye. The presence of cereal rye residue increased the time to 10% and 50% emergence of common waterhemp in both years but had less effect on common lambsquarters. The lack of weed emergence suppression seen in these experiments is a concern for cover crop use in Iowa\u27s conventional cropping systems, while the delay in weed emergence associated with cereal rye residue may be beneficial or detrimental to weed management. Greenhouse trials determined the soil activity of low rates of eleven corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] herbicides on five cover crops: cereal rye (Secale cereale L.), oat (Avena sativa L.), hairy vetch (Vicia villosa Roth), lentil (Lens culinaris Medik.), and radish (Raphanus sativus L.). Cereal rye was the most tolerant cover crop, whereas radish was the most sensitive species. Dry weight of radish was severely reduced by nearly all herbicides, whereas other cover crop species had smaller reductions due to herbicide injury. Root growth of oat was inhibited more by pendimethalin than the other species. Flumetsulam + clopyralid, atrazine, and herbicides containing isoxaflutole caused significant injury to most species studied. Though it is difficult to make direct comparisons between these experiments and the potential for injury in the field, these studies provide guidelines for growers wanting to include cover crops within their current rotation

The performance of model-based indices given alternative sampling strategies in a climate-adaptive survey design

Species-distribution shifts are becoming commonplace due to climate-driven change. Difficult decisions to modify survey extent and frequency are often made due to this change and constraining survey budgets. This often leads to spatially and temporally unbalanced survey coverage. Spatio-temporal models are increasingly used to account for spatially unbalanced sampling data when estimating abundance indices used for stock assessment, but their performance in these contexts has received little research attention. We therefore seek to answer two questions: (1) how well can a spatio-temporal model estimate the proportion of abundance in a new “climate-adaptive” spatial stratum? and (2) when sampling must be reduced, does annual sampling at reduced density or biennial sampling result in better model-based abundance indices? We develop a spatially varying coefficient model in the R package VAST using the eastern Bering Sea (EBS) bottom trawl survey and its northern Bering Sea (NBS) extension to address these questions. We first reduce the spatial extent of survey data for 30 out of 38 years of a real survey in the EBS and fit a spatio-temporal model to four commercially important species using these “data-reduction” scenarios. This shows that a spatio-temporal model generally produces similar trends and density estimates over time when large portions of the sampling domain are not sampled. However, when the central distribution of a population is not sampled the estimates are inaccurate and have higher uncertainty. We also conducted a simulation experiment conditioned upon estimates for walleye pollock (Gadus chalcogrammus) in the EBS and NBS. Many species in this region are experiencing distributional shifts attributable to climate change with species historically centered in the southeastern portion of the survey being increasingly encountered in the NBS. The NBS was occasionally surveyed in the past, but has been surveyed more regularly in recent years to document distributional shifts. Expanding the survey to the NBS is costly and given limited resources the utility of reducing survey frequency versus reducing sampling density to increase survey spatial extent is under debate. To address this question, we simulate survey data from alternative sampling designs that involve (1) annual full sampling, (2) reduced sampling in the NBS every year, or (3) biennial and full sampling in the NBS. Our results show that annual sampling, even with reduced sampling density, provides less biased abundance information than biennial sampling. We therefore conclude that ideally fishery-independent surveys should be conducted annually and spatio-temporal models can help to provide reliable estimates

Cell-specific single viral vector CRISPR/Cas9 editing and genetically encoded tool delivery in the central and peripheral nervous systems

CRISPR/Cas9 gene editing represents an exciting avenue to study genes of unknown function and can be combined with genetically encoded tools such as fluorescent proteins, channelrhodopsins, DREADDs, and various biosensors to more deeply probe the function of these genes in different cell types. However, current strategies to also manipulate or visualize edited cells are challenging due to the large size of Cas9 proteins and the limited packaging capacity of adeno-associated viruses (AAVs). To overcome these constraints, we developed an alternative gene editing strategy using a single AAV vector and mouse lines that express Cre-dependent Cas9 to achieve efficient cell-type specific editing across the nervous system. Expressing Cre-dependent Cas9 from a genomic locus affords space to package guide RNAs for gene editing together with Cre-dependent, genetically encoded tools to manipulate, map, or monitor neurons using a single virus. We validated this strategy with three common tools in neuroscience: ChRonos, a channelrhodopsin, for studying synaptic transmission using optogenetics, GCaMP8f for recording C

Pan-Arctic suitable habitat model for Greenland halibut

Deep-sea marine fishes support important fisheries but estimates of their distributions are often incomplete as the data behind them may reflect fishing practices, access rights, or political boundaries, rather than actual geographic distributions. We use a simple suitable habitat model based on bottom depth, temperature, and salinity to estimate the potential distribution of Greenland halibut (Reinhardtius hippoglossoides). A large presence-only dataset is examined using multivariate kernel densities to define environmental envelopes, which we link to spatial distribution using a pan-Arctic oceanographic model. Occurrences generally fit the model well, although there were gaps in the predicted circum-Arctic distribution likely due to limited survey activity in many of the ice-covered seas around the Arctic Ocean. Bottom temperature and depth were major factors defining model fit to observations, but other factors, such as ecosystem interactions and larval drift could also influence distribution. Model predictions can be tested by increasing sampling effort in poorly explored regions and by studying the connectivity of putative populations. While abundances of Greenland halibut in the High Arctic are currently low, some areas are predicted to be suitable habitat for this species, suggesting that on-going sea-ice melt may lead to fisheries expansion into new areas

The 2020 report of The Lancet Countdown on health and climate change: responding to converging crises

The Lancet Countdown is an international collaboration, established to provide an independent, global monitoring system dedicated to tracking the emerging health profile of the changing climate. The 2020 report presents 43 indicators across five sections: climate change impacts, exposures, and vulnerability; adaptation, planning, and resilience for health; mitigation actions and health co-benefits; economics and finance; and public and political engagement. This report represents the findings and consensus of the 35 leading academic institutions and UN agencies that make up the Lancet Countdown, and draws on the expertise of climate scientists, geographers, and engineers; of energy, food, and transport experts; and of economists, social and political scientists, data scientists, public health professionals, and doctors

Virology under the microscope—a call for rational discourse

Viruses have brought humanity many challenges: respiratory infection, cancer, neurological impairment and immunosuppression to name a few. Virology research over the last 60+ years has responded to reduce this disease burden with vaccines and antivirals. Despite this long history, the COVID-19 pandemic has brought unprecedented attention to the field of virology. Some of this attention is focused on concern about the safe conduct of research with human pathogens. A small but vocal group of individuals has seized upon these concerns – conflating legitimate questions about safely conducting virus-related research with uncertainties over the origins of SARS-CoV-2. The result has fueled public confusion and, in many instances, ill-informed condemnation of virology. With this article, we seek to promote a return to rational discourse. We explain the use of gain-of-function approaches in science, discuss the possible origins of SARS-CoV-2 and outline current regulatory structures that provide oversight for virological research in the United States. By offering our expertise, we – a broad group of working virologists – seek to aid policy makers in navigating these controversial issues. Balanced, evidence-based discourse is essential to addressing public concern while maintaining and expanding much-needed research in virology

Proceedings of the Thirteenth International Society of Sports Nutrition (ISSN) Conference and Expo

Meeting Abstracts: Proceedings of the Thirteenth International Society of Sports Nutrition (ISSN) Conference and Expo Clearwater Beach, FL, USA. 9-11 June 201

Management procedure evaluation of a data-limited multispecies fishery with application to the Hawaiian bottomfish fishery

Multispecies fisheries with technical interactions and sparse data present a challenge for assessment scientists, many of whom are now legally required to provide species-specific management advice. A key question is can these data be used to provide species-specific assessments and management advice? Secondly, in light of new assessment approaches, how would new management procedures perform with respect to the status quo? This thesis uses a novel multispecies model to reconstruct historical abundances using fishery-dependent data from the Hawaiian bottomfish fishery. In this handline fishery, hook competition and time spent handling fish limits catch rates, resulting in nonlinear relationships between CPUE and abundance. The model is jointly fit to species-specific catch and is conditioned on historical fishing effort. The model allows for hook competition and partitions time spent fishing and time spent handling fish, h. Simulation experiments showed this approach provided nearly unbiased parameter estimates unless an incorrect assumption was made about h. Empirical h estimates were unavailable, so a range of h values were imputed from information on fishing gears and sensitivity to h was evaluated. Species-specific information was disentangled using h, but no single value best described all species-specific catch equally. Leading and management parameter estimates were relatively insensitive to the assumed value of h, except for catchability at low stock size. Given the uncertainty about h, management procedure evaluation was used to evaluate management performance of the multispecies model to an aggregate model and evaluate alternative management procedures (MPs), defined by the decision rule, assessment model, and data types. Trade-offs among management objectives describing stability in catch, fishery productivity, and over-exploitation risk were compared. Trade-offs between catch and conservation objectives were largely determined by the decision rule. MPs associated with an aggregate assessment represented a balance from the aggregate perspective, but led to over-exploitation of one or more species. Average annual variation in catch was high for all MPs and highest for MPs using the multispecies approach in combination with a tag-recapture program. These results were largely robust to the assumptions about h in the assessment model and demonstrated the difficulty of co-managing multiple species.Science, Faculty ofZoology, Department ofGraduat