Littoral Greening: A Workshop to Understand the Drivers of Attached Filamentous Algal Blooms in Pristine Lakes; October, 2019 Lake Tahoe (CA-NV, USA)

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A puzzling pattern of coastal degradation has been observed in pristine, high water quality lakes around the world, including Lake Tahoe in the USA, Lakes Wakitipu and Taupō in New Zealand, and Lake Baikal in Russia. The nearshore and bottom edges of lakes are greening even though the watersheds in which these lakes reside have relatively low disturbance and the lakes are low in nutrients. Initial observations suggest the greening is from excessive growth of algae and bacteria that are now having consequences for the ecology of these lakes and the people that rely on them. So why are these algal blooms now common in lakes with high water quality? They are likely a result of many factors that are now interacting in new ways as environmental changes progress. This workshop brings together experts from a many science disciplines to discuss these changes and identify key questions that must be answered to explain why lakes with good water quality are suddenly changing. The organizers will recruit underrepresented members in science to engage in the topic and create a summary paper of the workshop findings in a publication that is accessible to the public via the internet. A special science session within at least one international science meeting will be created to engage scientists and managers of lake systems to continue discussions on this topic. This is the first workshop to address this emerging issue in ecosystem science. The primary workshop goals are to develop conceptual models to explain why usually inconspicuous filamentous algae are suddenly proliferating to nuisance levels in the nearshore-bottom of lakes. The conceptual models will be developed through discussions around basic research questions that highlight the potential mechanisms contributing to filamentous algae growth including but not limited to 1) How do climatically-induced changes in physical conditions affect nutrient and sediment dynamics in the nearshore zone? 2) Are remote lakes experiencing increased nutrient loading from anthropogenic groundwater pollution? 3) What is the role of animal grazers and changing biological communities in contributing to bottom algae growth? 4) Do moderate increases in nutrient availability associated with lakeshore development and atmospheric loading favor the growth of filamentous green algae and cyanobacteria? A series of premeetings via video conference will occur prior to the in-person meeting to maximize discussions and development of the conceptual models and answers to the key questions identified for this emerging issue.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.