Chad A Larson

Chad A Larson
Washington State Department of Ecology · Environmental Assessment Program

PhD

About

34
Publications
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Introduction

Publications

Publications (34)
Article
While resource enrichment can shape community structure and ecosystem functioning, how species diversity and biomass production respond to the input of multiple resources across habitats—particularly between terrestrial and aquatic ecosystems—remains poorly understood. Using a meta-analysis, we show that multiple resource addition consistently incr...
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Aim: The influences of environmental and spatial processes on species composition have been at the center of metacommunity ecology. Conversely, the relative importance of these processes for species co-occurrences and taxonomic similarity has remained poorly understood. We hypothesized that at a subcontinental scale, shared environmental preference...
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Motivation: Freshwater ecosystems have been heavily impacted by land-use changes, but data syntheses on these impacts are still limited. Here, we compiled a global database encompassing 241 studies with species abundance data (from multiplebiological groups and geographic locations) across sites with different land-use categories. This compilation...
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Motivation: Freshwater ecosystems have been heavily impacted by land-use changes, but syntheses on the impacts on freshwater ecosystems are still limited. Here, we compiled a global database encompassing 248 studies with species abundance data (from multiple taxon groups and geographic locations) across sites with different land-use categories. Thi...
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Hypersaline Great Salt Lake’s (GSL: Utah, USA) pelagic food web is dominated by the herbivore, Artemia franciscana. Artemia demographic responses (survival, developmental transition, and reproduction) to GSL salinities, temperatures, common phytoplankton and yeast, and food levels were examined by factorial experiment. Survival across developmental...
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Recent research on diatom metacommunities has focused on disentangling the assembly mechanisms driving species and functional composition and biodiversity across space and time, including deterministic (environmental filtering and biotic interactions) and stochastic processes (dispersal and ecological drift). In this chapter, we provide an overview...
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IInfluential ecological research in the 1980s, elucidating that local biodiversity (LB) is a function of local ecological factors and the size of the regional species pool (γ-diversity), has prompted numerous investigations on the local and regional origins of LB. These investigations, however, have been mostly limited to single scales and target g...
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The species–area relationship (SAR) has over a 150‐year‐long history in ecology, but how its shape and origins vary across scales and organisms remains incompletely understood. This is the first subcontinental freshwater study to examine both these properties of the SAR in a spatially explicit way across major organismal groups (diatoms, insects, a...
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Aim Niche and dispersal processes influence biodiversity, but their relative importance along latitude is unclear. We predicted that: (a) niche processes would dominate at high latitudes due to increased climatic stress, consistent with the physiological tolerance hypothesis and the Dobzhansky–MacArthur hypothesis and (b) dispersal limitation would...
Article
Globally, freshwater systems are threatened by climate change, so projections under various climate change scenarios are needed to inform efforts to protect and conserve already vulnerable taxa. Here, the change in distribution of stream vertebrates was investigated under different greenhouse gas emission scenarios. Using occurrence data from multi...
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The amounts and ratios of nutrients (nitrogen and phosphorus) are important determinants of producer community biodiversity and composition and their responses to climate and dispersal. However, the nutrient effects on co‐occurrence network topology, particularly in freshwaters, are understudied. Here, we investigate 1) whether nutrient supply and...
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Aim Biodiversity on Earth is threatened by climate change. Despite the vulnerability of freshwater habitats to human impacts, most climate change projections have focused on terrestrial systems. Here, we examined how current distributions and biodiversity of stream taxa may change under mitigated, stabilizing, and increasing greenhouse gas emission...
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Aim Biodiversity on Earth is threatened by climate change. Despite the vulnerability of freshwater habitats to human impacts, most climate change projections have focused on terrestrial systems. Here, we examined how the current distributions and biodiversity of stream taxa might change under mitigated, stabilizing and increasing greenhouse gas emi...
Article
Biofilms, composed of periphyton, bacteria and organic detritus, are the base of the food web in many streams and rivers. This media adsorbs and actively sequesters organic and inorganic contaminants from the water column. Here, we demonstrate the utility of using the contaminant concentrations in the biofilm matrix as an environmental media in sou...
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We developed a framework for the hierarchical pathways of bottom‐up (niche dimensionality) and top‐down control (herbivory) on biomass of stream algae via changes in guild composition (relative abundance of low profile, high profile, and motile guilds), species richness, and evenness. We further tested (1) the contrasting predictions of resource co...
Article
Survivability of diapausing (cryptobiotic) life stages over time in nature, beyond maximum observed time for viability, is not well understood. Because these life stages are an adaptation to overcome harsh conditions, survivability over time is assumed to be high. Brine shrimp (Artemia franciscana) diapausing eggs (cysts) permit overwinter survival...
Article
We report results from the first statewide assessment of biological health in perennial streams in Washington State. Using a probabilistic sampling survey design, we were able to make unbiased estimates of biological condition of macroinvertebrate communities throughout the state based on 346 sites sampled from 2009 to 2012. Results from randomly s...
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Determining the causes of biological impairment in urban stream settings presents unique challenges because there are many potential stressors associated with human development. A rigorous, scientifically based process is more likely to identify influential stressors that can be reduced to improve stream condition. We used the U.S. Environmental Pr...
Article
In this intercontinental study of stream diatoms, we asked three important but still unresolved ecological questions: (1) What factors drive the biogeography of species richness and species abundance distribution (SAD)? (2) Are climate-related hypotheses, which have dominated the research on the latitudinal and altitudinal diversity gradients, adeq...
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Cyanobacteria-dominated harmful algal blooms are increasing in occurrence. Many of the taxa contributing to these blooms are capable of fixing atmospheric nitrogen and should be favored under conditions of low nitrogen availability. Yet, synthesizing nitrogenase, the enzyme responsible for nitrogen fixation, is energetically expensive and requires...
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Aquatic monitoring programs vary widely in objectives and design. However, each program faces the unifying challenge of assessing conditions and quantifying reasonable expectations for measured indicators. A common approach for setting resource expectations is to define reference conditions that represent areas of least human disturbance or most na...
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The role of the number of limiting resources (NLR) on species richness has been the subject of much theoretical and experimental work. However, how the NLR controls temporal beta diversity and the processes of community assembly is not well understood. To address this knowledge gap, we initiated a series of laboratory microcosm experiments, exposin...
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The current paradigm that stream producers are under exclusive macronutrient control was recently challenged by continental studies, demonstrating that iron supply constrained diatom biodiversity. Using algal abundance and water chemistry data from the National Water-Quality Assessment Program, we determined for the first time community thresholds...
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Harsh environments are typically characterized by some dominant variable limiting diversity, making them interesting systems for studying how species diversity patterns change with abiotic conditions. Several environmental factors with the potential to influence phytoplankton diversity in hypersaline lakes were examined with microcosm experiments u...
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The accumulation of new and taxonomically diverse species is a marked feature of community development but the role of the environment in this process is not well understood. To address this problem, we subjected periphyton in laboratory streams to low (10 cm⋅sec(-1)), high (30 cm⋅sec(-1)), and variable (9-32 cm⋅sec(-1)) current velocity and low vs...
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In an effort to identify the causes and patterns of temporal change in periphytic communities, we examined biomass accumulation, taxonomic and functional composition, rate of species turnover, and pairwise species correlations in response to variability in current velocity and nutrient supply in artificial stream flumes. Divergent patterns in commu...
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The century-long research on succession has bestowed us with a number of theories, but little agreement on what causes species replacements through time. The majority of studies has explored the temporal trends of individual species in plant and much less so in microbial communities, arguing that interspecific interactions, especially competition,...
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Great Salt Lake (Utah, USA) is one of the world's largest hypersaline lakes, supporting many of the western U.S.'s migratory waterbirds. This unique ecosystem is threatened, but it and other large hypersaline lakes are not well understood. The ecosystem consists of two weakly linked food webs: one phytoplankton-based, the other organic particle/ben...
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A new technique for spectral fingerprinting of major algal groups in the freshwater periphyton (i.e. cyanobacteria, green algae, and diatoms) was developed using confocal laser scanning microscopy. This technique used the differential spectral emission signatures of photosynthetic algae and allowed their spatially explicit quantification and commun...
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Extinction of populations occurs naturally, but global extinction rates are accelerating, making understanding extinction a high priority for conservation. Extinction in experimental populations of brine shrimp (Artemia franciscana) was measured to assess hypothesized extinction processes. Greater initial population size, greater maximum population...

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