Walter K Dodds

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Verified

Walter verified their affiliation via an institutional email.

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• PhD
• Professor at Kansas State University

Gas transfer velocity (k600$$ {\mathrm{k}}_{600} $$) controls gas fluxes between aquatic ecosystems and the atmosphere. In streams, k600$$ {\mathrm{k}}_{600} $$ is controlled by turbulence and, thus, local hydrology and geomorphology. Resultantly, variability in k600$$ {\mathrm{k}}_{600} $$ can be large and modeling k600$$ {\mathrm{k}}_{600} $$ fro...

Abundant gizzard shad Dorosoma cepedianum (Lesueur, 1818) are thought to contribute to phytoplankton blooms by translocating nutrients from sediments to the water column where they can be readily taken up by phytoplankton and by consuming herbivorous zooplankton that might control phytoplankton. To assess the influence of gizzard shad relative abun...

Air–water gas exchange is essential to understanding and quantifying many biogeochemical processes in streams and rivers, including greenhouse gas emissions and metabolism. Gas exchange depends on two factors, which are often quantified separately: (1) the air–water concentration gradient of the gas and (2) the gas exchange velocity. There are fewe...

As science becomes ever more collaborative, the mechanisms for working in large and more diverse groups become more necessary. In the present article, I explore the utility of within-group collaboration agreements on participant conduct toward other project participants, within-group data sharing, and authorship of published manuscripts for researc...

For over a century, ecologists have used the concept of trophic state (TS) to characterize an aquatic ecosystem’s biological productivity. Because measuring productivity can be challenging within an ecosystem and across landscapes, multiple TS classification schemes, each relying on a variety of proxies for productivity, have emerged to meet use-sp...

Air-water gas exchange is essential to understanding and quantifying many biogeochemical processes in streams and rivers, including greenhouse gas emissions and metabolism. Gas exchange depends on two factors, which are often quantified separately: 1) the air-water concentration gradient of the gas and 2) the gas exchange velocity. There are fewer...

Recreational and occupational contact with freshwater harmful algal blooms (HABs) pose human health and economic risks worldwide. Individual U.S. states control monitoring, reporting, and mitigation of recreational exposure to HABs. We surveyed states to catalog responses to HAB problems. We used this data to develop a state‐specific HAB response i...

Thermodynamic properties of dissolved organic matter (DOM) influence river biogeochemistry. Using these properties to predict biogeochemical rates across rivers requires knowledge of how they vary. We employed mass spectrometry to quantify three DOM thermodynamic properties mechanistically linked to microbial respiration and biomass growth. We esti...

Water quality monitoring networks (WQMNs) that capture both the temporal and spatial dimensions are essential to provide reliable data for assessing water quality trends in surface waters, as well as for supporting initiatives to control anthropogenic activities. Meeting these monitoring goals as efficiently as possible is crucial, especially in de...

Carbon dioxide and methane emissions across tropical and subtropical inland water ecosystems in Brazil: meta-analysis of general patterns and potential drivers Investigations on CO2 and CH4 emissions from aquatic systems have increased in the last decades, but most studies focus on high-latitude water bodies, with limited information available for...

Fundamental aspects of human use of the environment can be explained by game theory. Game theory explains aggregate behaviour of the human species driven by perceived costs and benefits. In the ‘game’ of global environmental protection and conservation, the stakes are the living conditions of all species including the human race, and the playing fi...

Knowing reference (i.e., baseline) riverine nutrient concentrations is essential to understand fundamental processes of biogeochemical transport from continents to the ocean, describing ecological conditions, and informing managers of best attainable conditions for nutrient abatement and controlling anthropogenic eutrophication. We used data from 4...

Riparian zones and the streams they border provide vital habitat for organisms, water quality protection, and other important ecosystem services. These areas are under pressure from local (land use/land cover change) to global (climate change) processes. Woody vegetation is expanding in grassland riparian zones worldwide. Here we report on a decade...

Rivers that do not flow year-round are the predominant type of running waters on Earth. Despite a burgeoning literature on natural flow intermittence (NFI), knowledge about the hydrological causes and ecological effects of human-induced, anthropogenic flow intermittence (AFI) remains limited. NFI and AFI could generate contrasting hydrological and...

River metabolism and, thus, carbon cycling are governed by gross primary production and ecosystem respiration. Traditionally river metabolism is derived from diel dissolved oxygen concentrations, which cannot resolve diel changes in ecosystem respiration. Here, we compare river metabolism derived from oxygen concentrations with estimates from stabl...

Quantifying the trophic basis of production for freshwater metazoa at broad spatial scales is key to understanding ecosystem function and has been a research priority for decades. However, previous lotic food web studies have been limited by geographic coverage or methodological constraints. We used compound‐specific stable carbon isotope analysis...

Previous studies have evaluated how changes in atmospheric nitrogen (N) inputs and cli- mate affect stream N concentrations and fluxes, but none have synthesized data from sites around the globe. We identified variables controlling stream inorganic N concentrations and fluxes, and how they have changed, by synthesizing 20 time series ranging from 5...

Knowing where and when rivers flow is paramount to managing freshwater ecosystems. Yet stream gauging stations are dis- tributed sparsely across rivers globally and may not capture the diversity of fluvial network properties and anthropogenic influences. Here we evaluate the placement bias of a global stream gauge dataset on its representation of s...

Intermittent streams are characterized by significant periods of low to no flow, yet are also frequently subjected to flashy, high floods. Floods alter ecosystem function and result in variable successional patterns across the stream network. Yet, the timing of restored function after floods in intermittent stream networks is relatively unexplored....

Woody encroachment has impacted grassland ecohydrology worldwide, prompting management strategies aimed at woody vegetation removal to prevent or mitigate loss of water yield. We measured stream discharge following sustained cutting of riparian trees (2010–2020) in a native tallgrass prairie (northeastern Kansas, USA). Discharge has declined at thi...

We identified variables controlling stream nitrogen concentrations and fluxes, and how they have changed over time, by synthesizing 20 time series ranging from 5 to 51 years of data collected from forest and grassland dominated watersheds across Europe, North America, and East Asia and across four climate types (tropical, temperate, Mediterranean,...

Water quality monitoring networks (WQMNs) are essential to provide good data for management decisions. Nevertheless, some WQMNs may not appropriately reflect the conditions of the water bodies and their temporal/spatial dimensions, more particularly in developing countries. Also, some WQMNs may use more resources to attain management goals than nec...

Rivers and streams provide many ecosystem services, including provision of food, water purification, and nutrient abatement. Ecosystem functioning, the set of processes that regulate the fluxes of energy and matter, is the backbone of ecosystem services. A myriad of human impacts affects the functioning of running waters. To reduce these impacts, s...

Riparian zones, the interfaces between land and stream, perform vital ecosystem functions including transformation and retention of nutrients and sediment moving across the landscape. Although many studies assess transport through and transformation of materials in riparian zones, less is known about the direct influence of precipitation falling on...

We cover basic concepts and advances in stream ecology related to the River Continuum Concept (RCC). The RCC describes how position in the watershed influences rivers and streams. These influences include materials washing in from the watershed above and those properties dictated by terrestrial habitats that border the rivers or streams in the vici...

Dissolved organic carbon (DOC) and nitrogen (DON) are important energy and nutrient sources for aquatic ecosystems. In many northern temperate freshwater systems DOC has increased in the past 50 years. Less is known about how changes in DOC may vary across latitudes, and whether changes in DON track those of DOC. Here we present long‐term DOC and D...

Trophic state indexes (TSI) guide management strategies regarding eutrophication control worldwide. Such indexes usually consider chlorophyll-a (Chl-a), total phosphorus (TP), and Secchi disk depth (SDD) as independent variables for estimating aquatic productivity and the degree of impairment. TSIs for each of these components are frequently averag...

A global compilation of stream chemistry data was synthesized to evaluate spatial and temporal trends in solutes with a particular focus on dissolved organic matter and nitrogen (inorganic and organic forms). Data span a global array of streams and rivers ranging from the tropics to the arctic. Data include concentrations of dissolved organic nitro...

A comprehensive cross‐biome assessment of major nitrogen (N) species that includes dissolved organic N (DON) is central to understanding interactions between inorganic nutrients and organic matter in running waters. Here, we synthesize stream water N chemistry across biomes and find that the composition of the dissolved N pool shifts from highly he...

Non-perennial streams are widespread, critical to ecosystems and society, and the subject of ongoing policy debate. Prior large-scale research on stream intermittency has been based on long-term averages, generally using annually aggregated data to characterize a highly variable process. As a result, it is not well understood if, how, or why the hy...

River metabolism modeled from diurnal dissolved oxygen (DO) has become a widely used metric of ecosystem function, yet many papers provide insufficient methodological detail for replication. Only 79% of 43 sampled papers published from 2015 to 2019 mention calibration, 44% describe sensor placement, and 34% did not describe estimation approaches su...

Riparian ecosystems occupy land-water interfaces along upland-to-lowland and coastal gradients of river networks. Global changes in riparian vegetation alter the types and processing of organic matter at these interfaces and throughout river networks. Dominant pathways of structural changes in riparian vegetation are associated with (i) temperature...

The global environment annually receives thousands of tons of engineered nanomaterials (ENMs, particles less than 100 nm diameter). These particles have high active surface area, unique chemical properties, and can enter cells. Humanity uses many ENMs for their biological reactivity (e.g. microbicides), but their environmental effects are complex....

Understanding the complex and unpredictable ways ecosystems are changing and predicting the state of ecosystems and the services they will provide in the future requires coordinated, long-term research. This paper is a product of a U.S. National Science Foundation funded Long Term Ecological Research (LTER) network synthesis effort that addressed a...

We analyze here the nature of research in freshwater macrosystem biology (especially lotic studies) from both conceptual and current research perspectives. The boundaries of permanent and transitional lotic macrosystems from the smallest to largest spatial extents are described. We contrast ecosystem vs. macrosystem research and macroecology vs. ma...

Macrosystems are integrated human–natural systems, in recognition of the fact that virtually every natural system on Earth influences and is influenced by human activities, even over long distances. It is therefore crucial to incorporate inherent properties of broad‐scale systems, such as human–nature connectivity and feedbacks at multi‐scales, int...

In an era of unprecedented human impacts on the planet, macrosystems biology (MSB) was developed to understand ecological patterns and processes within and across spatial and temporal scales. We used machine‐learning and qualitative literature review approaches to evaluate the thematic composition of MSB from articles published since the 2010 creat...

Macrosystems biology research has expanded and evolved over the past decade as the scientific community grapples with ecological issues at regional to continental scales relevant to human interactions within the biosphere. Macrosystems biology builds on established fields of study like population and community ecology, biogeography, and global biog...

Over half of global rivers and streams lack perennial flow, and understanding the distribution and drivers of their flow regimes is critical for understanding their hydrologic, biogeochemical, and ecological functions. We analyzed nonperennial flow regimes using 540 U.S. Geological Survey watersheds across the contiguous United States from 1979 to...

Anthropogenic increases in nitrogen (N) and phosphorus (P) concentrations can strongly influence the structure and function of ecosystems. Even though lotic ecosystems receive cumulative inputs of nutrients applied to and deposited on land, no comprehensive assessment has quantified nutrient‐enrichment effects within streams and rivers. We conducte...

Secondary production estimates are an important element of ecosystem ecology because they facilitate quantification of the roles of consumers in material and energy cycling. We estimated production and resource consumption of stream macroinvertebrates, along with stream metabolism and organic matter storage in 3 relatively undisturbed Savanna headw...

Conceptual models underpin river ecosystem research. However, current models focus on continuously flowing rivers and few explicitly address characteristics such as flow cessation and drying. The applicability of existing conceptual models to nonperennial rivers that cease to flow (intermittent rivers and ephemeral streams, IRES) has not been evalu...

Rivers that cease to flow are globally prevalent. Although many epithets have been used for these rivers, a consensus on terminology has not yet been reached. Doing so would facilitate a marked increase in interdisciplinary interest as well as critical need for clear regulations. Here we reviewed literature from Web of Science database searches of...

Cattle degrade streams by increasing sediment, nutrient, and fecal bacteria levels. Riparian fencing is one best management practice that may protect water quality within many grazed lands. Here we surveyed the literature and summarized the responses of sediment, nutrient, and fecal indicator bacteria levels to riparian exclosure fencing in cattle-...

Freshwater Ecology

Plant, soil, and aquatic microbiomes interact, but scientists often study them independently. Integrating knowledge across these traditionally separate subdisciplines will generate better understanding of microbial ecological properties. Interactions among plant, soil, and aquatic microbiomes, as well as anthropogenic factors, influence important e...

Patch‐burn grazing (PBG) can promote terrestrial heterogeneity and biodiversity, but can temporarily increase stream nutrients and ecosystem metabolism, and alter macroinvertebrate assemblages. The impacts of grazing on stream channel morphology and post‐PBG recovery patterns are unclear. We assessed the influence of grazing in PBG managed grasslan...

Streamflow observations can be used to understand, predict, and contextualize hydrologic, ecological, and biogeochemical processes and conditions in streams. Stream gages are point measurements along rivers where streamflow is measured, and are often used to infer upstream watershed‐scale processes. When stream gages read zero, this may indicate th...

Biogeochemical rates within streams vary with ecosystem properties including the distribution of fishes. While many studies investigate the singular effect of fishes on ecosystem components, there is a limited understanding of how fish presence interacts with other ecosystem properties to affect ecosystem structure and function. Here, we used path...

Nonperennial rivers are a major—and growing—part of the global river network. New research and science-based policies are needed to ensure the sustainability of these long-overlooked waterways.

The reaeration coefficient (Ka20) is one of the main indicators of dissolved O2 movement to and from aquatic systems via the atmosphere. Direct gas tracer measurements, physical models, and models of O2 dynamics have been used for Ka20 estimation, especially in temperate aquatic ecosystems, with fewer examples in their tropical counterparts. Here w...

Quantifying ecosystem respiration remains challenging in aquatic ecosystems. Most investigators assume that nighttime and daytime respiration are equal. Recent studies suggest measuring dissolved oxygen isotopes during periods with and without photosynthesis can account for variations in daytime and nighttime respiration. These models are extremely...

Agricultural activities can affect the delivery of nutrients to streams, riparian canopy cover, and the capacity of aquatic systems to process nutrients and sediments. There are few measures of nutrient uptake and metabolism from tropical or sub-tropical streams in general, and even fewer from tropical regions of South America. We examined ammonium...

International cooperation will be required to solve global problems. International agreements, agencies, and organizations are discussed. The idea of a global society is explored.

Here I estimate the economic costs to solve each of the problems based on the steps necessary to solve them. This includes costs to protect the environment, eradicate diseases, protect against asteroids, protect against interruptions of food supply, stop naturally and bioterrorist-caused pandemics, and disarm nuclear weapons.

Here I provide other viewpoints on the worst problems. This includes informal surveys from several classes of students as well as discussions with an array of individuals. It also provides results of some large-scale surveys done by several different global initiatives.

The beginning of this chapter provides a view on how many people lack adequate nutrition globally. It considers the causes of hunger and the possibilities for feeding a growing human population as standards of living increase worldwide, requiring even more food production. The science behind increasing crop production is explained, the possibility...

This chapter is centered on both the potential for environmental harm that will negatively influence humans and the harm to the rest of the species on the planet. It provides data on the global economic benefits of maintaining the environment (ecosystem services). Then the discussion turns to the greenhouse effect, ozone depletion, limitations on q...

Here I provide my view on how global problems might be solved. This chapter suggests that there needs to be a new model of operation for global society and economics. The dangers and potential usefulness of thresholds and social media in the process of solving problems are guessed at. Consilience, enlightenment, and hope will be necessary to solve...

A general equation is introduced to allow comparison of environmental problems. The equation takes into account current and future potential for human deaths as well as current and future suffering. It deliberates over the unknowns in predicting the number of deaths and amount of suffering for major causes and how to compare death to suffering for...

This chapter delineates how I will define global problems including the general moral assumptions that will guide the approach taken in future chapters. It starts discussing the major causes of death currently and lists potential future catastrophes. It considers major global causes of suffering and how we can estimate risk of human death and suffe...

The chapter reviews diseases of humanity, both chronic disease and emergent diseases, that may harp much of humanity over short periods of time. It explains why the chances for pandemics are increasing and how they are inevitable. The threats of biological warfare and bioterrorism are covered, and the ways that we can stop pandemics are brought to...

Here we consider the possibility of global catastrophe from forces that are mostly out of human control. These causes include the Earth being struck by a large asteroid, explosion of a super volcano, and gamma ray bursts from the universe. Some potential technological threats are considered such as physics experiments gone wrong and global takeover...

Here I cover advances in social science that can be used to predict average human behavior. It considers costs and benefits to cooperation. There is also discussion of why some people are unwilling to accept scientific facts, even though it might ultimately not be in their best interests to do so. Finally, these aspects are considered with respect...

The basic science behind nuclear weapons and the global environmental effects of full-scale and more limited nuclear war are considered first in this chapter. These effects include nuclear winter, ozone depletion, electromagnetic pulses, and radiation poisoning. The possibility of nuclear terrorism and the potential for harm are discussed as well.

Agricultural, urban and industrial activities have dramatically increased aquatic nitrogen and phosphorus pollution (eutrophication), threatening water quality and biotic integrity from headwater streams to coastal areas world‐wide. Eutrophication creates multiple problems, including hypoxic “dead zones” that reduce fish and shellfish production; h...

Evolutionary history and adaptation to climate shape plant traits. Some include leaf traits that influence litter quality. Thus, evolutionary history should affect litter decomposition, a crucial ecosystem process. In addition, litter decomposition is directly influenced by climate. We consequently expect plant phylogeny, adaptation and climate to...

Understanding global ecological patterns and processes, from biogeochemical to biogeographical, requires broad‐scale macrosystems context for comparing and contrasting ecosystems. Climate gradients (precipitation and temperature) and other continental‐scale patterns shape freshwater environments due to their influences on terrestrial environments a...

The dissolved oxygen diel cycle is an inherent feature of stream ecosystems, and the amplitude in this diel fluctuation is thought to strongly influence the composition of stream communities. For instance, extremely low dissolved oxygen saturation (DDO) values have well-documented effects on stream macroinvertebrates. Less is known, however, about...

Riparian zones are key interfaces between stream and terrestrial ecosystems. Yet, we know of no whole-watershed experiments that cut only woody vegetation in the riparian zone in an otherwise intact watershed to isolate the role of riparian zones on stream ecology. We removed all of the woody riparian vegetation (from 10- and 30-m-wide buffers in h...

This book addresses the worst problems currently facing humanity and those that may pose future threats. The problems are explained and approached through a scientific lens, and categorized based on data involving global mortality, vulnerability, and threat level. The book presents indices of problem severity to compare relative intensity of curren...

Mounting evidence suggests ecosystem changes that alter subsurface water fluxes and carbon dioxide concentrations in carbonate terrains may drive measurable changes in chemical weathering rates, stream water chemistry, and flow path evolution on human timescales. We test this idea by exploring if the encroachment of woody vegetation into grasslands...

Stream restoration efforts have aimed at increasing hydraulic residence time (HRT) and transient storage (TS) to enhance nutrient uptake, but there have been few controlled studies quantifying HRT and TS influences on nutrient uptake dynamics. We assessed the effects of HRT and TS on ammonium (NH4⁺) and phosphate (PO43‐) uptake through controlled e...