Response of a Lake Michigan coastal lake to anthropogenic catchment disturbance

A paleolimnological investigation of post-European sediments in a Lake Michigan coastal lake was used to examine the response of Lower Herring Lake to anthropogenic impacts and its role as a processor of watershed inputs. We also compare the timing of this response with that of Lake Michigan to examine the role of marginal lakes as ‘early warning’ indicators of potential changes in the larger connected system and their role in buffering Lake Michigan against anthropogenic changes through biotic interactions and material trapping. Sediment geochemistry, siliceous microfossils and nutrient-related morphological changes in diatoms, identified three major trophic periods in the recent history of the lake. During deforestation and early settlement (pre-1845–1920), lake response to catchment disturbances results in localized increases in diatom abundances with minor changes in existing communities. In this early phase of disturbance, Lower Herring Lake acts as a sediment sink and a biological processor of nutrient inputs. During low-lake levels of the 1930s, the lake goes through a transitional period characterized by increased primary productivity and a major shift in diatom communities. Post-World War II (late 1940s–1989) anthropogenic disturbances push Lower Herring Lake to a new state and a permanent change in diatom community structure dominated by Cyclotella comensis . The dominance of planktonic summer diatom species associated with the deep chlorophyll maximum (DCM) is attributed to epilimnetic nutrient depletion. Declining Si:P ratios are inferred from increased sediment storage of biogenic silica and morphological changes in the silica content of Aulacoseira ambigua and Stephanodiscus niagarae . Beginning in the late 1940s, Lower Herring Lake functions as a biogeochemical processor of catchment inputs and a carbon, nutrient and silica sink. Microfossil response to increased nutrients and increased storage of biogenic silica in Lower Herring Lake and other regional embayments occur approximately 20–25 years earlier than in a nearby Lake Michigan site. Results from this study provide evidence for the role of marginal lakes and bays as nutrient buffering systems, delaying the impact of anthropogenic activities on the larger Lake Michigan system.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43091/1/10933_2004_Article_1688.pd

Open-inquiry experiments using sensors controlled by Arduinos in a pandemic-resilient lab course

In our open-source model of a pandemic-resilient flipped lab course, students pose their own research questions and devise their own physics experiments. Their major instruments are an Arduino and electronic sensors which they choose from the wide and growing selection of inexpensive devices based on solid-state and MEMS technologies. Supported by the open-source software and other online resources of the Maker movement, students are empowered to design and conduct experiments at home at intermediate and advanced levels. Using flipped-lab methods, instructors devote contact hours to coaching students in refining research questions and analyzing and interpreting data, while students get continual practice in communicating their own evolving goals and latest results to their instructors and classmates. While our pilot course continued virtually unchanged in the switch to virtual classes, our students' achievements show that these methods also bear consideration for inclusion even when all teaching activities can return to campus

Open-inquiry experiments using sensors controlled by Arduinos in a pandemic-resilient lab course

In our open-source model of a pandemic-resilient flipped lab course, students pose their own research questions and devise their own physics experiments. Their major instruments are an Arduino and electronic sensors which they choose from the wide and growing selection of inexpensive devices based on solid-state and MEMS technologies. Supported by the open-source software and other online resources of the Maker movement, students are empowered to design and conduct experiments at home at intermediate and advanced levels. Using flipped-lab methods, instructors devote contact hours to coaching students in refining research questions and analyzing and interpreting data, while students get continual practice in communicating their own evolving goals and latest results to their instructors and classmates. While our pilot course continued virtually unchanged in the switch to virtual classes, our students' achievements show that these methods also bear consideration for inclusion even when all teaching activities can return to campus.ImPhys/OpleidingTechnische Natuurkund

SPR statement on racial justice

Contains fulltext : 227229.pdf (Publisher’s version ) (Closed access)1 p

Colonização radicular de plantas cultivadas por Ralstonia solanacearum biovares 1, 2 e 3 Root colonization of cultivated plants inoculated with Ralstonia solanacearum biovar 1, 2 and 3

A murcha bacteriana causada por Ralstonia solanacearum é considerada a principal doença de origem bacteriana no mundo. Centenas de espécies de plantas pertencentes a mais de 50 famílias botânicas têm sido relatadas como hospedeiras. Foi avaliada, em condições de casa de vegetação, a colonização radicular de alface, arroz, cebolinha, ervilha, pepino e soja, por seis isolados de Ralstonia solanacearum (Rs), biovares 1, 2 e 3. Estirpes dos isolados de Rs com resistência múltipla aos antibióticos estreptomicina, rifampicina e cloranfenicol foram utilizadas. A colonização foi avaliada 45 dias após a inoculação, através do plaqueamento de suspensão de trituração em meio de cultura semi-seletivo. A ervilha comportou-se como hospedeira de todos os isolados mas, apenas um isolado da biovar 3 foi patogênico a esta espécie. A soja apresentou populações elevadas de quatro isolados distribuídos entre as três biovares e o pepino, de apenas dois isolados das biovares 1 e 3. Exceto para o isolado que foi patogênico à ervilha, as plantas não apresentaram sintomas da doença, comportando-se como hospedeiras não suscetível. O arroz apresentou populações muito baixas de todos os isolados. Alface e cebolinha não hospedaram nenhum dos isolados inoculados. Os resultados mostram a capacidade de Rs colonizar e sobreviver em diferentes espécies de plantas como rizobactérias.<br>Bacterial wilt caused by Ralstonia solanacearum is considered the main plant disease of bacterial origin in the world, where hundreds of plant species in more than 50 botanical families are host plants. Root colonization of lettuce (Lactuca sativa), rice (Oryza sativa), spring onion (Allium fistulosum), pea (Pisum sativum), cucumber (Cucumis sativus), and soybean (Glycine max) by six isolates of Ralstonia solanacearum (Rs) biovars 1, 2 and 3 was evaluated under greenhouse conditions. Bacterial strains resistant to streptomycin, rifampicin and chloranfenicol were used. Root colonization was evaluated 45 days after inoculation by counting bacteria in root extracts of culture media with antibiotics. Pea plants hosted all six isolates, but only the isolate biovar 3 was pathogenic to this species. High populations of four isolates of the three biovars were found on soybean, and cucumber hosted high population of only two isolates (biovars 1 and 3). Pea was a non-susceptible host for Rs, except for one pathogenic isolate. Rice hosted very low populations of all isolates, while lettuce and spring onion did not host any isolates. These results showed the ability of Rs to colonize and survive on different plant roots as rhizobacteria

Twentieth century water quality trends in Minnesota lakes compared with presettlement variability

Author Posting. © National Research Council Canada, 2004. This article is posted here by permission of National Research Council Canada for personal use, not for redistribution. The definitive version was published in Canadian Journal of Fisheries and Aquatic Sciences 61 (2004): 561-576, doi:10.1139/F04-015.A diatom-based transfer function was used to reconstruct water chemistry before European settlement in 55 Minnesota lakes. The lakes span three natural ecoregions, which differ in their history of land use, as well as in surficial geology, climate, and vegetation. Postsettlement trends were compared with water chemistry change reconstructed from two presettlement core sections (circa 1750 and 1800) as a measure of natural variability. Presettlement water quality changes were generally small and nondirectional in all three ecoregions. In contrast, half of the urban lakes showed a statistically significant increase in chloride, whereas 30% of urban and 30% of agricultural region lakes record a statistically significant increase in total phosphorus between 1800 and the present. These changes, which are attributed to road salt and nutrient runoff, are strongly correlated with the percentage of watershed area that is developed (residential or urban) in the case of chloride increases and the percentage of developed (metropolitan areas) or agricultural (agricultural areas) land in the case of nutrient increases. Water quality has changed little since 1800 for lakes in the forested regions of northeastern Minnesota. The few changes that are seen in this region are likely related to natural variations in climate or catchment soils.This work was funded by the Minnesota Legislature as recommended by the Legislative Commission on Minnesota Resources through a grant to the Minnesota Pollution Control Agency