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Diatom-based paleolimnological studies conducted ~25 years ago on five lakes (i.e., Big Rideau, Upper Rideau, Lower Rideau, Indian and Otter lakes) within the Rideau Canal system (Ontario, Canada) tracked extensive catchment disturbances related to canal construction (starting ca. 1828). Over the past three decades, these lakes have experienced additional environmental stressors including invasive zebra mussels and accelerated climate warming, warranting a paleolimnological re-assessment. We examine diatom compositional changes and visible range spectroscopy-inferred chlorophyll-a (VRS-Chla) trends over the past >200 years from sediment cores collected in 2019-2020 from these same lakes, with the aim of assessing environmental changes registered in these records since the original studies were undertaken ~25-30 years ago. Despite large-scale cultural disturbances, including extensive deforestation and flooding for canal construction, the most ecologically notable diatom changes in all sediment records occurred in the past ~25-30 years, and coincided with increases in VRS-Chla. During this recent period, small cyclotelloid and elongate planktonic diatoms increased in relative abundance, while large-celled Aulacoseira taxa declined. Exceptions to this trend include Upper Rideau Lake, where planktonic diatoms were scarce throughout the core and shifts occurred among benthic taxa, and Big Rideau Lake, which has a large littoral zone, where epiphytic diatoms became prominent in the past decade. These recent diatom changes could not be explained by nutrient enrichment, as measured total phosphorus (TP) concentrations have declined significantly since the 1970s. Increases in small planktonic taxa in some of the lakes also pre-date the ca. 1990 arrival of zebra mussels. We conclude that these recent changes were best explained by regional warming and declining wind speed resulting in new lake physical regimes. Such climate-driven changes are also consistent with the recent development of cyanobacterial blooms in these lakes, despite declining nutrient levels.

The Rideau Canal (Ontario, Canada) was constructed in the early 1830s, primarily as a means to transport military personnel, but now is primarily recreational. The construction of the canal and associated flooding, as well as other land-use changes, likely impacted lakes within the system, however, long-term monitoring data are not available. Furthermore, recent environmental changes, including accelerated climate warming, are affecting lake ecosystems. Shallow, macrophyte-dominated Lake Opinicon, which is part of the canal system, has been impacted by other various catchment disturbances over the past ~ 200 years. A previous diatom-based paleolimnological study conducted on the lake, examining a core collected in 1995, found that the diatom responses to a host of large-scale catchment disturbances were moderate compared to nearby deeper lakes. A more recent diatom-based study conducted on a 2019 core (the same core used in the present study) found similar results; however, over the most recent ~ 25–30 years a striking shift in diatom assemblage composition was documented, coinciding with increased regional climate warming. Nothing is known concerning long-term changes within the primary consumers linked to the array of disturbances. Here, we examined changes in cladoceran assemblages over the past ~200 years, using the 2019 sediment core, to track their response to various environmental stressors including climate warming. We found that pelagic Bosmina and Daphnia species began to increase in the early nineteenth century, consistent with the flooding of the lake during canal construction. The most ecologically notable changes in the cladoceran record, however, occurred in the most recent sediments. These were characterized by marked declines (often to trace abundances) in several littoral taxa, concurrent with a further increase in the relative abundance of small, pelagic Bosmina spp. This most recent compositional shift was consistent with accelerated regional climate warming and associated limnological changes, decreased total phosphorus (TP) concentrations, and changing food sources. These changes in primary consumers will likely cascade throughout the food web. [ABSTRACT FROM AUTHOR]

The emergence of an internal control system to guide operations along the Rideau Canal beginning in 1832 is examined through analysis of a book of directives (the Order Book) maintained by the lockmaster at the Isthmus lockstation. The Orders guided the work of the lockmaster and established general controls and control activities. Orders for adequate documents and records, physical control over assets and records, and proper authorization of activities were common. Orders are seen as efforts by British Royal Engineers, who were geographically removed from the oversight of the Rideau Canal Office, to discipline civilian lockmasters and to encourage lockmasters to govern themselves. Comparing the Order Book to Orders and Regulations in place in 1831 for the Royal Engineers also highlights similarities between expectations of Royal Engineers and those established for the civilian workforce under their direction, indicating a transfer of accounting technologies from the Royal Engineers to the civilian workforce. [ABSTRACT FROM AUTHOR]

The Rideau Canal National Historic Site is a complex social-ecological system that connects the Ottawa River and the St-Lawrence River in Eastern Ontario, Canada. As an interjurisdictional waterway, it presents interconnected social-ecological challenges. In this article, we analyze findings from five participatory workshops held with stakeholder groups in the Rideau Canal system. Participants in the workshops co-produced social-ecological relational maps that represent their knowledge and views about determinants of environmental health in the system. The maps were merged by the authors to create an aggregated, collective map grouping all factors that participants perceived as influencing the environmental health of the Rideau Canal. Our analysis focuses on two dimensions of these co-production exercises. First, we use concepts and methods from social-ecological systems and social network analysis to analyze the content of the maps, examining convergences and divergences in stakeholder perceptions of the system and outlining insights into social-ecological linkages that might be relevant for decision- and policy-makers. Most factors cited were social, emphasizing the need for more careful integration of the social and ecological in our understanding of complex historic waterway systems. Second, we examine the value of our workshops, anchored in collaborative systems thinking and network analysis, as a method for eliciting highly variable local knowledge and experiences, and for summarizing these in a consumable form for decision- and policy-makers. We argue that this method facilitates inclusion of various knowledges and perspectives in decision- and policymaking processes and provides pathways to improve social-ecological resilience. • Collaborative knowledge mapping elicits a range of knowledge and perspectives. • Our method aggregates views of the Rideau Canal as a social-ecological system. • Maps co-produced by participants had more social factors than ecological factors. • Co-produced knowledge maps provide narratives that can inform policy. • The narratives can help identify pathways to improve social-ecological resilience. [ABSTRACT FROM AUTHOR]

The art8icle focuses on future city, Ottawa 2120, by architect Zachary Colbert to exploring what the citizens of the meta-industrial city might produce and how they might interact with government. Topics discussed include aim to explore the politics of metaindustrial city through both the mundane moments of everyday life and possibilities of urbanism; relationship between life, work, and what it means to be a socially productive participant; and potential of tyrannical power.

Watershed-specific variables such as sediment particle size distribution, water depth, sedimentation rate, focusing factors, and catchment area to lake area ratio can affect the distribution of trace element contaminants to lakes. The aim of this study was to investigate sources of metals to three headwater lakes and to quantify effects of watershed-specific variables on spatial and temporal trends of trace elements (As, Cd, Co, Cr, Cu, Hg, K, Ni, Pb, Rb, and Zn) in sediments and mercury (Hg) concentrations in fish. Surface sediment and water samples were used to characterize spatial patterns, while sediment cores were collected to portray temporal trends. Historical trends of Hg in northern pike ( Esox lucius) were assessed in relation to paleolimnological trends of sediment Hg concentrations. Similarity in timing of sediment peak trace element concentrations for the lakes suggests large-scale, atmospheric sources. The lake with highest catchment area-to-lake area ratio was consistently associated with highest sediment elemental concentrations and displayed significant correlations between increased sediment Hg concentrations and decreased pike tissue concentrations over time. This suggests that catchment area-to-lake area ratio is an important factor influencing the concentration of atmospherically derived contaminants within lake sediments and their transfer through the food web. [ABSTRACT FROM AUTHOR]

In 1823–1824 Samuel Clowes prepared preliminary budget estimates for the construction of an inland waterway from Kingston, on Lake Ontario, to the Ottawa River in Upper Canada. An in-depth analysis of Clowes’ budget estimates explores their visual aspects: how the form and structure of the estimates are visual and how descriptive commentary included in the estimates aids readers in visualizing the proposed canal. The article then examines how the budget estimates are used for rhetorical purposes. The estimates are rhetorical both directly and indirectly. The ordered and logical visual form and structure of the estimates supports their rationality; claims of rationality are used in turn for rhetorical purposes. Further, properties of the estimates which allow readers to visualize the canal are rhetorical in their own right. Thus this article contributes to an understanding of early capital budgeting practices in canal building in North America, as well as to an understanding of accounting and budgeting as visual, rational and rhetorical. [ABSTRACT FROM PUBLISHER]

The New York Canal (now the Erie Canal) was first proposed in the New York Legislature in 1808 and eventually constructed from 1817 to 1825 through New York State to join Lake Erie and New York City. The Rideau Canal was proposed in 1816 and built from 1826 to 1832 to join the Ottawa River and Lake Ontario to facilitate transportation in Upper Canada (now the Province of Ontario, Canada). The compiled reports of the New York Canal Commissioners are compared with Upper Canada and British Parliamentary Papers to identify common challenges faced by engineers responsible for building the two canals. These challenges were natural, technical, social and managerial. The official reports for the canals reflect how these challenges were met - often in very similar ways - by the engineers engaged to survey, design and build the canals. Comparing these two canals provides insight into the challenges faced by all North American canal builders. [ABSTRACT FROM AUTHOR]

The relationship between government and the military is examined through the use of cost-benefit analysis (CBA) statements included in correspondence related to building the Rideau Canal. Discourse analysis is used to identify and evaluate CBA statements. CBA statements are used for rhetorical, technical and reporting purposes. Rhetorical uses of CBA predominate in the period leading up to the construction of the Rideau Canal. CBA as a tool for decision-making of a technical nature is common during the construction of the canal. CBA serves both rhetorical and technical purposes in progress reports. Patterns in the use of CBA in correspondence between government and military are also analysed and reveal a number of communication channels where communication using CBA statements between government and the military is either common or is lacking. [ABSTRACT FROM PUBLISHER]

The construction of the Rideau Canal was one of the greatest engineering accomplishments of the nineteenth century, creating a navigable waterway linking the Ottawa River with Lake Ontario. Colonel By Lake, located at the southern end of the canal near Kingston Mills, was created by the damming of the lower Cataraqui River. The canal flooding in 1831 raised water levels by almost 8 m, inundating former wetlands and lowland areas. European settlement in the pre-canal-era (ca. 1780s) was associated with widespread deforestation and limited flooding of wetlands by construction of mill dams. A detailed sediment coring program was conducted in Colonel By Lake to reconstruct the pre-canal environment and to document water level and land-use changes associated with European settlement and canal construction. The paleoenvironmental record was obtained through analysis of multiple environmental indicators including sediment facies, particle size, magnetic susceptibility and downcore changes in testate amoebae (thecamoebian) diversity. The core lithostratigraphy consists of organic-rich muds overlying peaty gyttja and a lowermost unit of fine to coarse silts. The canal flooding surface (ca. 1831) is clearly defined by a shift to finer grain sizes and increased magnetic susceptibility within the upper 40–60 cm. The shift is associated with an overall increase in thecamoebian abundance and diversity, and high numbers of Difflugia oblonga and Cucurbitella tricuspis that indicate a shift to a deeper and more eutrophic environment. In contrast, the pre-canal environment has lower thecamoebian abundance with assemblages characteristic of marsh environments ( Centropyxis constricta, Centropyxis aculeata). The onset of canal flooding (ca. 1790s) is identified by an increase in Pontigulasia compressa (~50 cm), recording a higher water flow rate. The study shows that a multi-proxy paleoenvironmental approach can clearly define different environmental changes due to land-use changes during colonisation and canal-era construction activities. [ABSTRACT FROM AUTHOR]

Chironomid (Diptera: Chironomidae) head capsules were studied from a core of recent sediments from shallow, macrophyte-dominated Lake Opinicon, Ontario, Canada, to determine if assemblages have changed in response to lake-level changes and other watershed disturbances, including deforestation and agriculture. Our results indicate that the construction of the Rideau Canal in the early 1830s and subsequent flooding of Lake Opinicon has had the greatest impact on this system, but that even this disturbance did not greatly affect chironomid assemblages. Despite other significant cultural disturbances in the watershed, the lake sediments have recorded only minor changes in its recent history, providing support for the hypothesis of alternative lake equilibria. These results correspond well with diatom inferences of only minor changes in past lake trophic status. [ABSTRACT FROM AUTHOR]