Predator-prey interactions of zooplankton from a shallow endorheic lake: Little Fish Lake, Nevada

The zooplankton community of Little Fish Lake exists in a seasonally and interannually variable physical environment. This shallow endorheic lake is particularly sensitive to climatic variability; depth and salinity fluctuate during periods of prolonged evaporation or precipitation. I examined zooplankton seasonal succession in Little Fish Lake during a period of relatively low salinity from March 1995 through March 1996. The community was more diverse during my study than it had been in periods of high salinity. While abiotic conditions probably affected the community structure, biotic interactions such as predation likely influenced succession as well. I observed interactions between the predaceous rotifer Asplanchna silvestrii and six potential prey species with which it co-occurs. Since A. silvestrii occurs in three morphologically and behaviorally distinct morphotypes, I assessed the vulnerability of prey with each predator morphotype. Predator morphotype and prey type both significantly affected the outcome of each predation event. These predator-prey interactions are particularly interesting because all the species commonly occur in alkaline, saline lakes where biotic interactions may be relatively simple due to the scarcity of organisms that can tolerate the unusual chemical conditions

The Rise and Fall of Plankton: Long-Term Changes in the Vertical Distribution of Algae and Grazers in Lake Baikal, Siberia

Both surface water temperatures and the intensity of thermal stratification have increased recently in large lakes throughout the world. Such physical changes can be accompanied by shifts in plankton community structure, including changes in relative abundances and depth distributions. Here we analyzed 45 years of data from Lake Baikal, the world’s oldest, deepest, and most voluminous lake, to assess long-term trends in the depth distribution of pelagic phytoplankton and zooplankton. Surface water temperatures in Lake Baikal increased steadily between 1955 and 2000, resulting in a stronger thermal gradient within the top 50 m of the water column. In conjunction with these physical changes our analyses reveal significant shifts in the daytime depth distribution of important phytoplankton and zooplankton groups. The relatively heavy diatoms, which often rely on mixing to remain suspended in the photic zone, shifted downward in the water column by 1.90 m y-1, while the depths of other phytoplankton groups did not change significantly. Over the same time span the density-weighted average depth of most major zooplankton groups, including cladocerans, rotifers, and immature copepods, exhibited rapid shifts toward shallower positions (0.57–0.75 m y21). As a result of these depth changes the vertical overlap between herbivorous copepods (Epischura baikalensis) and their algal food appears to have increased through time while that for cladocerans decreased. We hypothesize that warming surface waters and reduced mixing caused these ecological changes. Future studies should examine how changes in the vertical distribution of plankton might impact energy flow in this lake and others

Research Recommendations from the Airplane Simulation Transfer Literature

This descriptive review aims to identify research gaps in the airplane, simulation transfer of training literature. The research question is: What are the recommendations for future research from the simulation experiments using a true transfer or a quasi-transfer design to study the near or far transfer of airplane flying knowledge, skills, or abilities among adults? The method involves an exhaustive survey of English-language, peer-reviewed publications available online. The results include eight seminal reviews of the aviation literature published since 1973, 26 empirical studies published since 2004, and four general reviews to situate the aviation literature. The primary transfer studies encompass four themes: training proficiency, motion, abnormal events, and control tasks. This review addresses current research needs by presenting summaries and recommendations from the transfer literature, identifying gaps, and proposing an agenda for future research. It serves to inform researchers, practitioners, manufacturers, and regulators in the field of flight simulation training

Skills and Knowledge for Data-Intensive Environmental Research.

The scale and magnitude of complex and pressing environmental issues lend urgency to the need for integrative and reproducible analysis and synthesis, facilitated by data-intensive research approaches. However, the recent pace of technological change has been such that appropriate skills to accomplish data-intensive research are lacking among environmental scientists, who more than ever need greater access to training and mentorship in computational skills. Here, we provide a roadmap for raising data competencies of current and next-generation environmental researchers by describing the concepts and skills needed for effectively engaging with the heterogeneous, distributed, and rapidly growing volumes of available data. We articulate five key skills: (1) data management and processing, (2) analysis, (3) software skills for science, (4) visualization, and (5) communication methods for collaboration and dissemination. We provide an overview of the current suite of training initiatives available to environmental scientists and models for closing the skill-transfer gap

Ecology under lake ice

Winter conditions are rapidly changing in temperate ecosystems, particularly for those that experience periods of snow and ice cover. Relatively little is known of winter ecology in these systems, due to a historical research focus on summer ‘growing seasons’. We executed the first global quantitative synthesis on under‐ice lake ecology, including 36 abiotic and biotic variables from 42 research groups and 101 lakes, examining seasonal differences and connections as well as how seasonal differences vary with geophysical factors. Plankton were more abundant under ice than expected; mean winter values were 43.2% of summer values for chlorophyll a, 15.8% of summer phytoplankton biovolume and 25.3% of summer zooplankton density. Dissolved nitrogen concentrations were typically higher during winter, and these differences were exaggerated in smaller lakes. Lake size also influenced winter‐summer patterns for dissolved organic carbon (DOC), with higher winter DOC in smaller lakes. At coarse levels of taxonomic aggregation, phytoplankton and zooplankton community composition showed few systematic differences between seasons, although literature suggests that seasonal differences are frequently lake‐specific, species‐specific, or occur at the level of functional group. Within the subset of lakes that had longer time series, winter influenced the subsequent summer for some nutrient variables and zooplankton biomass

'Equity' in the pandemic treaty : the false hope of 'access and benefit-sharing'

During COVID-19 the international community repeatedly called for the equitable distribution of vaccines and other medical countermeasures. However, there was a substantial gap between this rhetoric and state action. High-income countries secured significantly more doses than they required, leaving many low-income countries unable to vaccinate their populations. Current negotiations for the new Pandemic Treaty under the World Health Organization (WHO) attempt to narrow the gap between rhetoric and behaviour by building the concept of equity into the Treaty's substantive content. But equity is difficult to define, much less to operationalize. Presently, WHO member states appear to have chosen "access and benefit sharing" (ABS) as the sole mechanism for operationalizing equity in the Treaty. This paper examines ABS as a mechanism, its use in public health, and argues that ABS is fundamentally flawed, unable to achieve equity. It proposes other options for an equitable international response to future pandemic threats

The Grizzly, December 7, 1999

Student Crimes On College Campuses • Biology Major Woes: Schedule Changes Leave Students Frustrated • Rich Barrett Scores his 1,000th Career Point • Talent Show Displays Ursinus Students\u27 Skills • AIDS Quilt Displayed in Helfferich Gym • Democratic Candidate for U.S. Senate Will Speak at Ursinus • Omwake: The House of Ill Repute • Final Exam Schedule • Lovin\u27 it at Louie\u27s • Letter to the Editors • Singing Group Edges out Magician • Ursinus College Choir Presents Messiah • Women\u27s Volleyball; The Year in Review and their Run to the ECAC\u27s • Wrestling Struggles in Tourney • Men\u27s Hoopsters Net First Win • Ursinus Swimming Falls to Red Devils of Dickinson • Seniors Remembered: Teammates Reflect on Departing Upperclassmenhttps://digitalcommons.ursinus.edu/grizzlynews/1454/thumbnail.jp