Lake Mendota Research Articles

Bacterial production of free fatty acids from freshwater macroalgal cellulose

The predominant strategy for using algae to produce biofuels relies on the overproduction of lipids in microalgae with subsequent conversion to biodiesel (methyl-esters) or green diesel (alkanes). Conditions that both optimize algal growth and lipid accumulation rarely overlap, and differences in growth rates can lead to wild species outcompeting the desired lipid-rich strains. Here, we demonstrate an alternative strategy in which cellulose contained in the cell walls of multicellular algae is used as a feedstock for cultivating biofuel-producing microorganisms. Cellulose was extracted from an environmental sample of Cladophora glomerata-dominated periphyton that was collected from Lake Mendota, WI, USA. The resulting cellulose cake was hydrolyzed by commercial enzymes to release fermentable glucose. The hydrolysis mixture was used to formulate an undefined medium that was able to support the growth, without supplementation, of a free fatty acid (FFA)-overproducing strain of Escherichia coli (Lennen et. al 2010). To maximize free fatty acid production from glucose, an isopropyl β-D-1-thiogalactopyranoside (IPTG)-inducible vector was constructed to express the Umbellularia californica acyl-acyl carrier protein (ACP) thioesterase. Thioesterase expression was optimized by inducing cultures with 50 μM IPTG. Cell density and FFA titers from cultures grown on algae-based media reached 50% of those (∼90 μg/mL FFA) cultures grown on rich Luria-Bertani broth supplemented with 0.2% glucose. In comparison, cultures grown in two media based on AFEX-pretreated corn stover generated tenfold less FFA than cultures grown in algae-based media. This study demonstrates that macroalgal cellulose is a potential carbon source for the production of biofuels or other microbially synthesized compounds.

Seasonal differences in bacterial community composition following nutrient additions in a eutrophic lake

We examined the effects of nutrient amendments on epilimnetic freshwater bacteria during three distinct periods in the eutrophic Lake Mendota's seasonal cycle (spring overturn, summer stratification and autumn overturn). Microcosm treatments enriched solely with phosphorus containing compounds did not result in a large bacterial community composition (BCC) change or community activity response (assessed via alkaline phosphatase activity, APA) relative to the controls during any season. Treatments enriched with carbon- and nitrogen-containing compounds resulted in a dramatic BCC change and a large APA increase in the autumn and spring seasons, but only treatments receiving carbon, nitrogen and phosphorus (CNP) exhibited similar responses in the summer season. Despite the fact that the amendments created similar CNP concentration conditions across seasons, the BCC following amendment greatly varied among seasons. 16S rRNA gene sequence analysis indicated that many common freshwater bacterial lineages from the Alpha- and Betaproteobacteria class and Bacteroidetes phylum were favoured following nutrient (CNP) addition, but individual taxa were generally not favoured across all seasons. Targeted quantitative PCR analysis revealed that the abundance of the Actinobacteria acIB1 cluster decreased in all microcosms during all three seasons, while the Flavobacterium aquatile (spring) and ME-B0 (summer) clusters of Bacteroidetes increased following CNP addition. These results suggest a particular bacterial group is not universally favoured by increased nutrient loads to a lake; therefore, efforts to predict which bacteria are involved in nutrient cycling during these periods must take into account the seasonality of freshwater bacterial communities.

Meeting report: 2010 Caenorhabditis elegans Neurobiology Meeting, University of Wisconsin, USA

Against the backdrop of the scenic Lake Mendota, the C. elegans Neurobiology Meeting came to a head. Expertly organised by Brian Ackley and Bruce Bamber and hosted at the accommodating University of Wisconsin, the meeting brought together recent contributions from many of the major research groups working on the neurobiology of C. elegans. With seven keynote speakers, 57 verbal presentations and hundreds of posters, this exciting event spanned a fascinating 3days from 27 June to 30 June 2010. In keeping with the tradition of this conference, the event on the whole was spearheaded by young investigators from several research institutions. The meeting served to emphasise the gains enjoyed by taking advantage of the genetic tractability of the worm. A thread that ran through the meeting was the importance of integrating data across different levels of biological organisation to permit delineation of the physiology underpinning discrete behavioural states. Recent advances in optogenetics and microfluidics were at the forefront of refining these analyses. The presentations discussed in this meeting report are a selection which reflects this overarching theme.

Review

Book Reviews 163 zoomorphic forms (bears, birds, and snakes) and spirit beings (longtailed water spirits, thunderbirds) in the study area were constructed between AD 700 and AD 1100 by Late Woodland peoples. Birmingham further argues that these served as cyclic world-renewal mechanisms. The author also nicely interweaves interdisciplinary histories of the investigators (e.g., Charles E. Brown, A. B. Stout) and the investigated, especially in chapter 3. As Regna Darnell has noted in Invisible Genealogies: A History of Americanist Anthropology (2001), “genealogies” of theoretical and methodological mentoring and influence were already well developed in American anthropology and archaeology by the period 1900 to 1920. For example, Charles E. Brown and Arlow B. Stout were not practicing formative archaeology and ethnohistory in a vacuum, and each maintained links to Orin G. Libby, who was at the time secretary of the State Historical Society of North Dakota. Stout went on to a prolific four-decade career at the New York Botanical Garden. Chapters 4 through 8 discuss the Four Lakes district (Lakes Mendota, Monona, Waubesa, and Kegonsa) cultural landscape—highlighting mound complexes and associated sites. These chapters are written to serve as a literary “tour” of the corresponding landscape (p. 114). Neither the casual reader nor the professional archaeologist or historian will be disappointed by Robert Birmingham’s well-crafted narrative. Abundant accompanying photographs, maps, and figures complement and supplement the text. Lastly, the historic preservation message (in chapter 9) of the text is brought home equally by what is said as well as what is not. Cultural resources are nonrenewable—once they are gone, they are gone forever. Spirits of Earth accomplishes the general and specific goals set for it and for the public who may embrace its message. Paul R. Picha, Chief Archaeologist State Historical Society of North Dakota, Bismarck Patrick Brode. The Slasher Killings: A Canadian Sex-Crime Panic, 1945-1946. Detroit: Wayne State University Press, 2009. Pp. 229. Illustrations. Index. Notes. Paper, $22.95. In the summers of 1945 and 1946, five men in Windsor, Ontario, were stabbed, two fatally, by an assailant the local paper dubbed the Slasher. In The Slasher Killings, Patrick Brode, a lawyer and the author of several books on Canadian legal history, provides a comprehensive 164 Michigan Historical Review narrative of the case, chronicling its social impact as well as the way these crimes were investigated and adjudicated. Brode traces the case’s historical context on both national and local levels, particularly how it was related to popular and professional perceptions of homosexuality. The result is a carefully constructed history of a specific criminal panic in a particular city that also speaks to historical issues that affected people and communities across postwar North America. Brode relies on newspaper articles, official records, and personal interviews to reconstruct how—and with what consequences—the Slasher case created a moral panic specific to the Windsor area. He is particularly effective in demonstrating how the reactions of the police force and ordinary citizens, coupled with the inflammatory press coverage of the case, inflated and distorted the possible threat that the Slasher represented, thus prompting disproportionate reactions to that danger. At first, perceived outsiders were thought to be the best suspects: vagrants, members of racial minorities, and virtually anyone else who “did not belong” (p. 2). However, when the Slasher resurfaced in 1946 (after the police had discovered that he was targeting homosexuals), sexual “deviants” became the prime suspects, and the panic in Windsor began to feed into a panic that was developing across the United States and Canada. The case seemed to reinforce the common postwar association of homosexuality with violent, predatory compulsions at a time when there were severe and widespread anxieties about sexual psychopathology. It did so at first by drawing attention to Windsor’s gay subculture in connection with this series of violent attacks. This attention only increased after eighteen-year-old Ronald Sears confessed to the Slasher attacks under police questioning in 1946. Sears claimed to have been molested as a child. He appeared to think this abuse was homosexual in nature rather than the act of a pedophile. Thus Sears’s motive for the crimes was to avenge himself against the...

Estimates of phosphorus entrainment in Lake Mendota: a comparison of one‐dimensional and three‐dimensional approaches

Entrainment of phosphorus across the thermocline can be an important nutrient source for phytoplankton in stratified lakes. In eutrophic stratified lakes, seasonal entrainment can be responsible for delayed recovery following a decrease in external phosphorus load. We compared seasonal estimates of entrainment derived from single‐ and multilocation thermocline migration approaches. Entrainment estimates from these methods were similar. A sampling approach based on a single centralized location produced whole‐lake entrainment estimates in general agreement with the mean value from the multilocation approach (the single‐location approach reasonably reproduced patterns at a weekly and seasonal time scale). In this study, it was not essential to account for spatial variation in estimating annual rates of entrainment. We also estimated entrainment based on a three‐dimensional (3‐D) hydrodynamic model over a short period of significant thermocline migration. The 3‐D model was most useful in exposing spatial and temporal variation in temperature and phosphorus profiles that are otherwise difficult to observe. Spatial variation in phosphorus profiles was associated with upwelling of metalimnetic water represented by the 3‐D model. These transient dynamics, though a relatively small portion of an annual phosphorus budget, may supply nutrients to epilimnetic phytoplankton during periods of nutrient limitation. There is a need for further research that combines 3‐D hydrodynamic modeling with field collection of biological and chemical data.

Coherence between lake ice cover, local climate and teleconnections (Lake Mendota, Wisconsin)

Summary Ice duration has shortened and the ice-off date has become earlier for Lake Mendota from 1905 to 2000 as air temperatures have warmed and snowfall has increased. In addition, the ice record has cyclic components at inter-annual and inter-decadal scales. We examined the frequency domain relations between ice, local climate and the teleconnections, Southern Ocean Oscillation (SOI), Pacific Decadal Oscillation (PDO), North Atlantic Oscillation (NAO), and Northern Pacific Index (NP), through a three-tiered analysis of coherence. The coherence results provide evidence of linear relations between the three levels at inter-annual and inter-decadal frequencies. Of the three local climate variables analyzed, namely temperature, snowfall and snow depth, temperature is the variable that most significantly affects ice duration and ice-off date, at both inter-annual and inter-decadal frequencies. The most significant effect of teleconnections on local climate are the effects of PDO on snowfall and snow depth, and SOI on temperature, at inter-annual frequencies, and the effect of NAO on snowfall at inter-decadal frequencies. The teleconnections that most significantly affect ice-cover duration and ice-off date, particularly at inter-decadal frequencies, are the PDO and the NAO. The influence of PDO on ice-cover appears to be transmitted through temperature, while the influence of the NAO appears to be transmitted through temperature and snowfall. A cascading set of links between teleconnections, local climate, and lake ice explain some, but not all, of the dynamics in these time series.

Trend and oscillations in the ice-cover duration of Lake Mendota, Wisconsin, USA / Tendance et oscillations de la durée d'englacement du Lac Mendota, Wisconsin, USA

The 150-year time series of ice duration in Lake Mendota, Wisconsin was analysed to investigate possible effects of climate variability, and a non-parametric test confirmed a significant, decreasing trend. Singular-spectrum analysis (SSA) and the multi-taper method (MTM) of spectral analysis revealed a nonlinear trend and quasi-periodic oscillations. Analysis of the linearly detrended series showed significant frequencies ranging from quasi biennial to >100 years. The interannual and interdecadal signals detected are within the range of periodicity of the El Niño-Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) modes of variability. A smoothing procedure was used to separate low frequencies, or trend, and higher frequencies. Four reconstructed components of the low-pass-filtered time series were sufficient to explain 95% of the filtered series variance. The reconstruction showed signals with periods longer than 20 years that could be associated with the PDO. The series showed a relatively constant trend between approximately 1895 and 1965, and a steep declining trend in the last 40 years. Twenty four reconstructed components of the high-frequency residuals were required to explain 90% of the variance in the residual series. The reconstruction showed interdecadal signals that could be associated with the PDO and signals with periods between two and seven years that could be associated with the Southern Oscillation Index (SOI). Results of a coherence analysis showed that ice-cover duration is significantly correlated with the PDO for periods longer than about 20 years, and with the SOI for periods between two and seven years. The results suggest a relationship between the decreasing ice duration since about 1970 and the accompanying increase in Northern Hemisphere mean annual surface temperature. This interpretation agrees with previous descriptions of observed historic changes that appear to be related to anthropogenic activity.

Characteristics and Influence of Phosphorus Accumulated in the Bed Sediments of a Stream Located in an Agricultural Watershed

We investigated the accumulation and influence of bioavailable P (BAP) in sediments of a stream located in an agricultural area of the Lake Mendota watershed in Wisconsin, USA. During hydrologic events, the stream carried high concentrations of suspended sediment (up to 250 mg/l) and BAP (up to 2.5 mg/l). Bed sediments were highly enriched in BAP, as inventories of BAP in the top 10 cm of sediment ranged from 143 to 14,500 μg P/cm2. Space variations in BAP inventories were related to site-specific hydrodynamics and geochemical factors, including iron (Fe; r 2 = 0.71) and aluminum (Al; r 2 = 0.54) concentrations. Most sites behaved as potential sinks for dissolved reactive phosphate during hydrologic events and potential sources during base-flow periods. Through the combination of site-specific factors and geochemical controls, Dorn Creek modifies the amount, timing, and composition of P delivered from the watershed to downstream sites and water bodies.

Probabilistic Estimate of a Threshold for Eutrophication

Regime shifts, or massive changes in ecosystems, are often associated with thresholds in drivers such as climate, land-use change, nutrient fluxes, or other factors. A frequently studied example is eutrophication, which is a serious environmental problem of lakes and reservoirs associated with phosphorus (P) enrichment above a threshold. We estimated probability distributions of thresholds for eutrophication of Lake Mendota, Wisconsin, USA using 30 years of annual P budgets. Although thresholds were likely to influence eutrophication of the lake (probability 96.6%), the probability distributions of thresholds spanned a wide range of P loading rates. Management recommendations are consistent with simpler models that recommend P load targets near or below the lowest P loads observed in the past 30 years. If loads increase, there is considerable risk of crossing a threshold to sustained eutrophication with high in-lake P concentrations and poor water quality. On the other hand, if loads decrease there is a chance of crossing a mitigation threshold, causing substantial reductions in P concentrations and improvements in water quality. Consideration of these risks will increase estimates of the net economic benefits of lower P loading. Our analysis illustrates a process for estimating probability distributions for thresholds of ecosystem regime shifts. Even though threshold probability distributions may be wide with thick tails, they provide crucial information about potential consequences of alternative policy choices.

Estimating the Risk of Exceeding Thresholds in Environmental Systems

Environmental regulations often rely on limits or thresholds to indicate an acceptable pollutant load. Estimates of the Risk of Exceeding such Thresholds (RET) are often based on a single model deemed to be the best for the particular pollutant or particular case. However, if many models make different predictions but explain the data almost equally well, predictions based on a single model may omit important information contained in other models that fit almost as well as the “best” single model. More accurate assessments of RET may result if multiple models are considered. We compared performance of the single best model relative to that of an ensemble of models estimated by bagging (Bootstrap AGGregatING) using the example of soil P concentrations and the risk of exceeding environmental limits of soil P concentrations in the watershed of Lake Mendota, Wisconsin, USA. Bagging yielded significantly better predictions of the risk of exceeding a threshold level of soil P (99.6% accuracy versus 74% for single-model prediction at a 20 mg kg−1 threshold). Use of multiple model techniques can improve estimates of RET over a range of realistic thresholds in other management situations where thresholds are important including eutrophication, desertification, fisheries, and many types of pollution control.

Perspectives on the eutrophication of the Yahara lakes

Eutrophication of the four Yahara lakes—Mendota, Monona, Waubesa, and Kegonsa—near Madison, Wisconsin, has been dramatic since the mid-1800s. For Lake Mendota, the erosion of sediments from higher water levels established by the damming of the lake's outlet, plus the agricultural expansion of its watershed, resulted in blue-green algal growths. These impacts, however, were dwarfed by water quality problems stemming from Madison's wastewater inputs that directly entered Lake Monona from the late 1800s through 1936, and then Lake Waubesa until 1958. Blue-green algal blooms were so bad in the lower Yahara lakes that the Madison Public Health Department conducted major copper sulfate treatments during 1925–1954. During the wastewater input years, inorganic nitrogen (N) and especially dissolved reactive phosphorus (DRP) concentrations in the surface waters were very high (particularly in Waubesa and Kegonsa), indicating neither nutrient was limiting algal growth. No P legacy from the wastewater inputs was found in Waubesa and Kegonsa's sediments; minimal P-binding potential due to low iron (Fe) availability is the hypothesized reason. Mendota's algal blooms were not a problem until the mid-1940s when wastewater inputs from upstream communities increased as well as the agricultural use of N and P fertilizers. This increase in eutrophication symptoms coincided with an increase in indices of DRP and inorganic N concentrations in the lake. After wastewater diversion in 1971, blue-green algal blooms persisted in Lake Mendota, and the onus of the problem shifted to agricultural and urban nonpoint source pollution. While much progress has been made in recent years to control these pollution sources to Mendota, manure runoff during late winter continues as a management problem. As evidence, P loadings during January to March constituted 48% of total loadings measured for 1990–2006 in the Yahara River subwatershed. Much of this runoff P was dissolved and not associated with high sediment loads, whereas during other months, more of the runoff P was bound to sediments that could settle out in lower stream reaches prior to entering the lake. However, low P-binding potential of recently deposited sediments in Mendota along with signs of water quality improvements following periods of drought indicate the lake could respond rapidly to nutrient input reductions. Finally, DRP and inorganic N concentrations since 1980 have indicated that algal growth in the Yahara lakes during July–August may have been limited by not only P, but N (especially in the lower Yahara lakes). Aggressive programs to reduce inputs from both nutrients will be important to prevent scum-forming blue-green algal blooms and filamentous algal growths that could become problematic once zebra mussels become established in the Yahara lakes.

Correction to “Volcanic eruptions and climate”

[1] In the paper ‘‘Volcanic eruptions and climate’’ by Alan Robock (Reviews of Geophysics, 38(2), 191–219, 2000), two errors have been found on page 197. [2] While preparing for a presentation on the 25th anniversary of the April 1982 El Chichon volcanic eruption, I found the original slide used for Plate 4 and discovered that it had been developed in July 1982 rather than the date of April 1983 given in the paper. I had had copies made of this slide and erroneously had used the date on a copy of the slide rather than the original date when writing the paper. Therefore the corrected caption should read as follows: [3] Plate 4. Sunset over Lake Mendota in Madison, Wisconsin, in July 1982, three months after the El Chichon eruption. Photograph by A. Robock. [4] On the same page as Plate 4, the statement, ‘‘The famous 1893 Edvard Munch painting, ‘The Scream,’ shows a red volcanic sunset over the Oslo harbor produced by the 1892 Awu eruption,’’ is incorrect with regard to the eruption that produced the red and yellow sky. As pointed out subsequently by Olson et al. [2004], it was the memory of the spectacular sunsets from the 1883 Krakatau eruption that inspired Munch to use a volcanic sunset 10 years later in ‘‘The Scream.’’

Interannual dynamics and phenology of bacterial communities in a eutrophic lake

We investigated patterns of intra‐ and interannual change in pelagic bacterial community composition (BCC, assessed using automated ribosomal intergenic spacer analysis) over six years in eutrophic Lake Mendota, Wisconsin. A regular phenology was repeated across years, implying that freshwater bacterial communities are more predictable in their dynamics than previously thought. Seasonal events, such as water column mixing and trends in water temperature, were most strongly related to BCC variation. Communities became progressively less similar across years between the months of May and September, when the lake was thermally stratified. Dissolved oxygen and nitrate + nitrite concentrations were highly correlated to BCC change within and across seasons. The relationship between BCC and seasonal drivers suggests that trajectories of community change observed over long time series will reflect large‐scale climate variation.

Comparison of Primer Sets for Use in Automated Ribosomal Intergenic Spacer Analysis of Aquatic Bacterial Communities: an Ecological Perspective

Two primer sets for automated ribosomal intergenic spacer analysis (ARISA) were used to assess the bacterial community composition (BCC) in Lake Mendota, Wisconsin, over 3 years. Correspondence analysis revealed differences in community profiles generated by different primer sets, but overall ecological patterns were conserved in each case. ARISA is a powerful tool for evaluating BCC change through space and time, regardless of the specific primer set used.

Autonomous detection of cryospheric change with hyperion on-board Earth Observing-1

On-board detection of cryospheric change in sea ice, lake ice, and snow cover is being conducted as part of the Autonomous Sciencecraft Experiment (ASE), using classifiers developed for the Hyperion hyper-spectral visible/infrared spectrometer on-board the Earth Observing-1 (EO-1) spacecraft. This classifier development was done with consideration for the novel limitations of on-board processing, data calibration, spacecraft targeting error and the spectral range of the instrument. During on-board tests, these algorithms were used to measure the extent of cloud, snow, and ice cover at a global suite of targets. Coupled with baseline imaging, uploaded thresholds were used to detect cryospheric changes such as the freeze and thaw of lake ice and the formation and break-up of sea ice. These thresholds were used to autonomously trigger follow-up observations, demonstrating the capability of the technique for future planetary missions where downlink is a constrained resource and there is high interest in data covering dynamic events, including cryospheric change. Before upload classifier performance was assessed with an overall accuracy of 83.3% as measured against manual labeling of 134 scenes. Performance was further assessed against field mapping conducted at Lake Mendota, Wisconsin as well as with labeling of scenes that were classified during on-board tests.

Exploring ecological patterns with structural equation modeling and Bayesian analysis

Structural equation modeling is a multivariate statistical method that allows evaluation of a network of relationships between manifest and latent variables. In this statistical technique, preconceptualizations that reflect research questions or existing knowledge of system structure create the initial framework for model development, while both direct and indirect effects and measurement errors are considered. Given the interesting features of this method, it is quite surprising that the number of applications in ecology is limited, and even less common in aquatic ecosystems. This study presents two examples where structural equation modeling is used for exploring ecological structures; i.e., summer epilimnetic phytoplankton dynamics. Both eutrophic (Lake Mendota) and mesotrophic (Lake Washington) conditions were used to test an initial hypothesized model that considered the regulatory role of abiotic factors and biological interactions on lake phytoplankton dynamics and water clarity during the summer stratification period. Generally, the model gave plausible results, while a higher proportion of the observed variability was accounted for in the eutrophic environment. Most importantly, we show that structural equation modeling provided a convenient means for assessing the relative role of several ecological processes (e.g., vertical mixing, intrusions of the hypolimnetic nutrient stock, herbivory) known to determine the levels of water quality variables of management interest (e.g., water clarity, cyanobacteria). A Bayesian hierarchical methodology is also introduced to relax the classical identifiability restrictions and treat them as stochastic. Additional advantages of the Bayesian approach are the flexible incorporation of prior knowledge on parameters, the ability to get information on multimodality in marginal densities (undetectable by standard procedures), and the fact that the structural equation modeling process does not rely on asymptotic theory which is particularly important when the sample size is small (commonly experienced in environmental studies). Special emphasis is given on how this Bayesian methodological framework can be used for assessing eutrophic conditions and assisting water quality management. Structural equation modeling has several attractive features that can be particularly useful to researchers when exploring ecological patterns or disentangling complex environmental management issues.

Comprehensive approaches for managing and restoring two large lakes and their catchments: Pyhäjärvi (Finland) and Lake Mendota (USA)

(2005). Comprehensive approaches for managing and restoring two large lakes and their catchments: Pyhajarvi (Finland) and Lake Mendota (USA) SIL Proceedings, 1922-2010: Vol. 29, No. 2, pp. 830-836.

A Predictive Approach to Nutrient Criteria

Violation of a water quality standard triggers the need for a total maximum daily load (TMDL); this should result in actions that improve water quality, but sometimes at significant cost. If the standard is well-conceived, a designated-use statement characterizes societal values, and a criterion provides a measurable surrogate for designated use. This latter provision means that scientists measure the criterion and view violations of the criterion as equivalent to noncompliance with the designated use. However, if a criterion is not a good indicator of designated use, it is apt to result in misallocation of the limited resources for water quality improvement through the TMDL process. This concern provides the basis for our assessment of the national nutrient criteria strategy recently proposed by the U.S. EPA. We acquired data sets for four case studies (Lake Washington, Neuse River Estuary, San Francisco Bay, and Lake Mendota) and then used expert elicitation to quantify designated-use attainment for each case. Applying structural equation modeling, we identified good water quality criteria as the best predictors of the designated use elicited response variable. Further, we used the model to relate the level (concentration) of each criterion to the probability of compliance with the designated use; this provides decision-makers with an estimate of risk associated with the criterion level, facilitating the selection of appropriate water quality criteria.

A TEST OF THE ENVIRONMENTAL KUZNETS CURVE USING LONG‐TERM WATERSHED INPUTS

The Environmental Kuznets Curve (EKC) postulates that environmental quality is initially degraded with increasing economic prosperity, until reaching some turning point where environmental quality improves with increases in wealth. Tests using environmental indicators beyond those that affect human health have been less supportive of the EKC idea. We hypothesize that environmental changes impacting human health are more likely to show evidence of an EKC than variables less directly related to human health. Furthermore, the EKC hypothesis assumes that ecological damage is reversible, and we argue that this assumption is not always valid. We test for evidence of an EKC in Dane County, Wisconsin, using non‐point‐source pollution time series data for Lake Mendota throughout the 20th century. We examine metals deposited in lake sediments (cadmium, chromium, copper, and lead), other non‐point‐source pollutants such as sulfur and dissolved reactive phosphorus (DRP), and water clarity (measured by Secchi disk depth). We relate changes in ecological variables to changes in real wealth per capita (RWPC) in Dane County over time. The EKC did not describe the relationship between all ecological and economic indicators tested; however, several variables were related to RWPC. Our strongest results (for Secchi depth, DRP, and copper) show increasing pollution with increasing wealth. Secchi depth and DRP are related to water quality and clarity, which have value to society but less direct, immediate health consequences. P pollution may also be fairly irreversible over short time scales. The best models and plots for cadmium, chromium, and lead suggest improvements in environmental quality with increases in RWPC, although these trends were not statistically significant. Results for sulfur were inconclusive. Overall, wealth did not explain much of the variability in any of the ecological variables examined here, suggesting that consideration of additional factors are necessary to explain their dynamics. Economic prosperity cannot be expected to improve all aspects of the environment, but may be biased toward aspects that are ecologically reversible phenomena or of concern to human health.

History of the Future: Luso-Brazilian Studies in the New Millennium

I am grateful for the invitation to speak this afternoon and for the opportunity to return to Madison once again, at this privileged location on the shores of Lake Mendota. We are here among friends and colleagues to celebrate the Luso-Brazilian Review and its contributions to our field, during almost 40 years of publication, and to take up its timely invitation to consider the future of Luso-Brazilian Studies in the new millennium. As the directors of the journal may have known or suspected, I first began studies of Portuguese language at the University of Wisconsin-Madison at the same date that the first issue of the journal appeared, Summer 1965. The premier issue carried essays by many of the most prominent scholars in the field-an inspiring introduction for future students-and reading the Luso-Brazilian Review has been, ever since, a mainstay of scholarship in the flagship journal in our field. Everyone in the Luso-Brazilian field owes an immense debt to the University of Wisconsin, which established and has maintained one of America's premier programs. Let us take a moment to express our appreciation and gratitude for the pioneering work and foresight over the decades that is responsible at the University of WisconsinMadison for preserving a strong and vital program in Portuguese and Luso-Brazilian studies, which remains a model for the nation. From the beginning, the Luso-Brazilian Review recognized our field's multidisciplinary nature, by publishing in the most diverse historical periods, geographical areas, and linguistic features of what can be called the Portuguese world. Significantly, the journal identifies the current moment that brings us together as one of change in the way our field is structured, taught, and administered in US academic institutions. It recognizes the need to reevaluate traditional disciplinary boundaries, examine the institutional context, evaluate new materials and methods of research, and reach an assessment of the status of Luso-Brazilian studies at the onset of a new millennium. Marked by foresight and far-reaching objectives, this ambitious meeting is symbolically, if not in fact, a continuation of the six international colloquia on Luso-Brazilian Studies organized almost half-a-century ago, which contributed to form the identity and vitality of what was then a newly active field of studies.