URBANIZATION INFLUENCES ON AQUATIC COMMUNITIES IN NORTHEASTERN ILLINOIS STREAMS1

ABSTRACT: Biotic indices and sediment trace element concentrations for 43 streams in northeastern Illinois (Chicago area) from the 1980s and 1990s were examined along an agricultural to urban land cover gradient to explore the relations among biotic integrity, sediment chemistry, and urbanization. The Illinois fish Alternative Index of Biotic Integrity (AIBI) ranged from poor to excellent in agricultural/rural streams, but streams with more than 10 percent watershed urban land (about 500 people/mi²) had fair or poor index scores. A macroinvertebrate index (MBI) showed similar trends. A qualitative habitat index (PIBI) did not correlate to either urban indicator. The AIBI and MBI correlated with urban associated sediment trace element concentrations. Elevated copper concentrations in sediment occurred in streams with greater than 40 percent watershed urban land. The number of intolerant fish species and modified index of biotic integrity scores increased in some rural, urbanizing, and urban streams from the 1980s to 1990s, with the largest increases occurring in rural streams with loamy/sandy surficial deposits. However, smaller increases also occurred in urban streams with clayey surficial deposits and over 50 percent watershed urban land. These data illustrate the potentially complex spatial and temporal relations among biotic integrity, sediment chemistry, watershed urban land, population density, and regional and local geologic setting.     

Climate change vulnerability of the US Northeast winter recreation– tourism sector

Winter recreation is an important part of the cultural identity of the Northeast United States and is a multibillion dollar contributor to the regional economy. This study examined the vulnerability of the two largest winter recreation industries, snowmobiling and alpine skiing, to four climate change scenarios for the twenty-first century. Under all scenarios, natural snow became an increasingly scarce resource. The diminished natural snow pack had a very negative impact on the snowmobile industry. As early as 2010–2039, 4 to 6 of the 15 snowmobile study areas were projected to lose more than half of the current season. Reliable snowmobile seasons (>50 days) were virtually eliminated in the region under the A1Fi scenarios by 2070–2099. The large investment in snowmaking substantially reduced the vulnerability of the ski industry and climate change posed a risk to only 4 of the 14 ski areas in 2010–2039, where average ski seasons declined below 100 days and the probability of being open for the entire Christmas–New Year’s holiday declined below 75%. Conversely, by 2070–2099 only four ski study areas had not reached these same economic risk criteria. In order to minimize ski season losses, snowmaking requirements are projected to increase substantially, raising important uncertainties about water availability and cost. Climate change represents a notable threat to the winter recreation sector in the Northeast, and the potential economic ramifications for businesses and communities heavily invested in winter tourism and related real estate is sizeable.     

Fetal cardiac intervention—Perspectives from a single center

Fetal cardiac intervention was first proposed in the early 1990s to impact cardiac development and survival of fetuses with fetal aortic stenosis and evolving hypoplastic left heart syndrome (HLHS). Although initial attempts of fetal aortic valvuloplasty were unsuccessful and carried a high rate of morbidity and mortality, our collaborative group at the Brigham and Women's Hospital and Boston Children's Hospital have reinvigorated the procedure using improvements in imaging, anesthesia, balloon catheters, and surgical techniques. Two decades of experience have now allowed us to document the safety of in utero intervention and to achieve a better understanding of the impact of midgestation intervention on developing HLHS. Research into underlying genetics, predictive biomarkers, and ways to incorporate stem cell technology will hopefully allow us to further refine the procedure to most benefit children with this historically lethal disease.     

Structural equation modelling in perspective

Four current controversies in structural equation modelling are reviewed; the “causal” nature of structural equation models, the assessment of global fit, the use of specification searches to enhance model fit, and the call for a return to “simpler” forms of analysis. Within each area the nature of the controversy is reviewed and suggestions made to improve future practice.