Lake diatom responses to warming: reviewing the evidence
TL;DR: This article examined the role that climate-mediated alterations in inter-related lake processes have played on diatom community composition, dynamics and size structure, with particular attention to the recent success of planktonic diatom species relative to heavier tychoplanktonic and small benthic diatoms.
Abstract: Algae, the dominant primary producers in many aquatic ecosystems, are critical to global biogeochemical cycling, and changes in their abundance and composition can cascade throughout aquatic food webs. Diatoms often dominate the algal communities in many freshwater systems. Their population dynamics are affected by a variety of environmental variables, many of which are linked to changes in water column properties and habitat availability, which themselves can be linked to shifts in ice cover, length of the growing season, thermal stability and stratification, vertical mixing patterns, habitat alterations, and the availability of resources such as light and nutrients. Climate has strong moderating controls on all of these fundamental aquatic processes, which can directly and indirectly alter species composition, abundance and seasonal dynamics of both periphytic and planktonic diatoms. In this review, we examine the role that climate-mediated alterations in inter-related lake processes have played on diatom community composition, dynamics and size structure, with particular attention to the recent success of planktonic diatom species relative to heavier tychoplanktonic and small benthic diatoms. We focus primarily on paleolimnological records, but also reference a wide spectrum of limnological and physiological studies to review and discuss how climate-driven shifts in lake properties may affect diatom assemblage reorganization. Understanding the limnological and historical context of these often complex diatom changes is key to making scientifically defensible interpretations of paleolimnological records. We further evaluate the plausibility of alternative explanations (e.g. atmospheric nitrogen deposition) for the recent success of small cyclotelloid species by examining trends in these planktonic diatoms from a large number of sites. Using a weight-of-evidence approach, we conclude that recent climate change is the main driver that has led to ecological tipping points resulting in the recent success of small planktonic diatoms that have been reported in many aquatic systems.
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University of Florida1, Katholieke Universiteit Leuven2, James Cook University3, Queensland Museum4, University of Melbourne5, University of Queensland6, Chinese Academy of Sciences7, University of Cambridge8, BirdLife International9, Zoological Society of London10, Norwegian Polar Institute11, University of Hong Kong12, Sapienza University of Rome13, Stellenbosch University14, University of British Columbia15, University of Hawaii16, National University of Singapore17, Wildlife Conservation Society18
TL;DR: The full range and scale of climate change effects on global biodiversity that have been observed in natural systems are described, and a set of core ecological processes that underpin ecosystem functioning and support services to people are identified.
Abstract: Most ecological processes now show responses to anthropogenic climate change. In terrestrial, freshwater, and marine ecosystems, species are changing genetically, physiologically, morphologically, and phenologically and are shifting their distributions, which affects food webs and results in new interactions. Disruptions scale from the gene to the ecosystem and have documented consequences for people, including unpredictable fisheries and crop yields, loss of genetic diversity in wild crop varieties, and increasing impacts of pests and diseases. In addition to the more easily observed changes, such as shifts in flowering phenology, we argue that many hidden dynamics, such as genetic changes, are also taking place. Understanding shifts in ecological processes can guide human adaptation strategies. In addition to reducing greenhouse gases, climate action and policy must therefore focus equally on strategies that safeguard biodiversity and ecosystems.
815 citations
University of Western Ontario1, Colorado State University2, Utah State University3, University of Maine4, University of California, Davis5, Academy of Sciences of the Czech Republic6, University of Innsbruck7, Portland State University8, University of Nevada, Reno9, United States Geological Survey10, University of Wisconsin-Madison11, Queen's University12, SUPSI13, University of California, Santa Barbara14
TL;DR: A review and update of the growing body of research that shows that sediments in remote mountain lakes archive regional and global environmental changes, including those linked to climate change, altered biogeochemical cycles, and changes in dust composition and deposition, atmospheric fertilization, and biological manipulations can be found in this paper.
Abstract: Mountain lakes are often situated in protected natural areas, a feature that leads to their role as sentinels of global environmental change. Despite variations in latitude, mountain lakes share many features, including their location in catchments with steep topographic gradients, cold temperatures, high incident solar and ultraviolet radiation (UVR), and prolonged ice and snow cover. These characteristics, in turn, affect mountain lake ecosystem structure, diversity, and productivity. The lakes themselves are mostly small, and up until recently, have been characterized as oligotrophic. This paper provides a review and update of the growing body of research that shows that sediments in remote mountain lakes archive regional and global environmental changes, including those linked to climate change, altered biogeochemical cycles, and changes in dust composition and deposition, atmospheric fertilization, and biological manipulations. These archives provide an important record of global environmental change that pre-dates typical monitoring windows. Paleolimnological research at strategically selected lakes has increased our knowledge of interactions among multiple stressors and their synergistic effects on lake systems. Lakes from transects across steep climate (i.e., temperature and effective moisture) gradients in mountain regions show how environmental change alters lakes in close proximity, but at differing climate starting points. Such research in particular highlights the impacts of melting glaciers on mountain lakes. The addition of new proxies, including DNA-based techniques and advanced stable isotopic analyses, provides a gateway to addressing novel research questions about global environmental change. Recent advances in remote sensing and continuous, high-frequency, limnological measurements will improve spatial and temporal resolution and help to add records to spatial gaps including tropical and southern latitudes. Mountain lake records provide a unique opportunity for global scale assessments that provide knowledge necessary to protect the Earth system.
159 citations
Cites background from "Lake diatom responses to warming: r..."
..., 2018) here and around the world (Rühland et al., 2015)....
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124 citations
University of Vermont1, Leibniz Association2, Free University of Berlin3, University of Savoy4, Virginia Tech5, Shizuoka University6, Griffith University7, University of Potsdam8, University of Geneva9, University of South Florida10, University of Helsinki11, National Scientific and Technical Research Council12, National Institute for Environmental Studies13, Rollins College14, Estonian University of Life Sciences15, United States Geological Survey16, Swiss Federal Institute of Aquatic Science and Technology17, Helmholtz Centre for Environmental Research - UFZ18, Cornell University19, Indian Ministry of Environment and Forests20, Queen's University21, University of Konstanz22, Vrije Universiteit Brussel23, ETH Zurich24, Uppsala University25, University of Oldenburg26, National Institute of Water and Atmospheric Research27, Dundalk Institute of Technology28, University of Waterloo29, Academy of Sciences of the Czech Republic30, City University of New York31, Miami University32
TL;DR: A comprehensive synthesis is provided that identifies how storms interact with lake and watershed attributes and their antecedent conditions to generate changes in lake physical and chemical environments and suggests future research directions across a gradient of lake types and environmental conditions.
Abstract: In many regions across the globe, extreme weather events such as storms have increased in frequency, intensity, and duration due to climate change. Ecological theory predicts that such extreme events should have large impacts on ecosystem structure and function. High winds and precipitation associated with storms can affect lakes via short-term runoff events from watersheds and physical mixing of the water column. In addition, lakes connected to rivers and streams will also experience flushing due to high flow rates. Although we have a well-developed understanding of how wind and precipitation events can alter lake physical processes and some aspects of biogeochemical cycling, our mechanistic understanding of the emergent responses of phytoplankton communities is poor. Here we provide a comprehensive synthesis that identifies how storms interact with lake and watershed attributes and their antecedent conditions to generate changes in lake physical and chemical environments. Such changes can restructure phytoplankton communities and their dynamics, as well as result in altered ecological function (e.g., carbon, nutrient and energy cycling) in the short- and long-term. We summarize the current understanding of storm-induced phytoplankton dynamics, identify knowledge gaps with a systematic review of the literature, and suggest future research directions across a gradient of lake types and environmental conditions.
114 citations
Additional excerpts
...…Wiseman, and Clarke (1984) Scheffer, Rinaldi, Gragnani, Mur, and van Nes (1997), Reynolds et al. (2002) Reynolds, Oliver, and Walsby (1987)* Rühland et al. (2015)* Paerl and Otten (2013) Abiotic variables Nutrient loading (internal or external) − + − ± ± + ± Decreased Zeu/Zmix + − + + + +…...
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...…(diatoms) Aphanizomenon spp. (Cyanobacteria) Example references Jones (1988), Clegg, Maberly, and Jones (2003), Salonen, Jones, and Arvola (1984) Rühland et al. (2015)* Reynolds, Wiseman, and Clarke (1984) Scheffer, Rinaldi, Gragnani, Mur, and van Nes (1997), Reynolds et al. (2002) Reynolds,…...
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TL;DR: In this article, the authors compare diatom records and other proxy data archived in lake sediment cores from the Chinese Loess Plateau to compare the Chinese summer monsoon intensity, lake trophic status and aquatic ecosystem responses during warming periods over the past two millennia.
Abstract: Historically, warm periods enhanced the Asian summer monsoon—increased rainfall brought additional nutrients to freshwater ecosystems and increased production. However, anthropogenic aerosols have weakened the monsoon and altered lake ecosystems. Anthropogenic aerosol increases over the past few decades have weakened the Asian summer monsoon1,2,3 with potentially far-reaching socio-economic and ecological repercussions. However, it is unknown how these changes will affect freshwater ecosystems that are important to densely populated regions of Asia. High-resolution diatom records and other proxy data archived in lake sediment cores from the Chinese Loess Plateau allow the comparison of summer monsoon intensity, lake trophic status and aquatic ecosystem responses during warming periods over the past two millennia. Here we show that an abrupt shift towards eutrophic limnological conditions coincided with historical warming episodes4,5, marked by increased wind intensity and summer monsoon rainfall leading to phosphorus-laden soil erosion and natural lake fertilization. In contrast, aerosol-affected Anthropocene warming catalysed a marked weakening in summer monsoon intensity leading to decreases in soil erosion and lake mixing. The recent warm period triggered a strikingly different aquatic ecosystem response with a limnological regime shift marked by turnover in diatom species composition now dominated by oligotrophic taxa, consistent with reductions in nutrient fertilization, reduced ice cover and increased thermal stratification6. Anthropogenic aerosols have altered climate–monsoon dynamics that are unparalleled in the past ∼2,000 years, ushering in a new ecological state.
102 citations
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"Lake diatom responses to warming: r..." refers background in this paper
...In tropical lakes where water temperatures are typically high, differences in the vertical temperature gradient are relatively small, but nonetheless strong density differences develop at these high water temperatures (Hutchinson 1957)....
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3,224 citations