Explore the vast range of titles available.

\" W. T. Edmondson has spent his career answering questions about the ecological impacts of human experiments on lakes in Washington State. In this volume, he recounts these studies and captures from his experiences a larger view of the nature of our environmental problems. . . . While the commentary is wide ranging, the foundation is a personal account of one ecologist's lifetime experience on the dual points of research and public application of that research.\"-Research and Exploration\"W. T. Edmondson, a zoologist, extracts enduring lessons from his more than 50 years of experience in persuading political powers to make use of scientific knowledge when they set about drawing up laws for managing human interventions in the environment. Any scientist who follows in Edmondson's footsteps should benefit from reading this sensitive recounting of political battles.\"-Garrett Hardin, Pacific Northwest Quarterly

As cities grow, lakes are often assumed to suffer from increasing non‐point pollution. Many waterbodies have become more eutrophic in recent decades, as expected—but many others became less eutrophic, especially in urban/suburban areas. What policies, practices, and ecosystem processes have helped some lakes stay stable or become less eutrophic even in a growing city? Identifying and understanding success stories are important to continue protecting these lakes and improving other urban/suburban lakes. We found one such success story when we examined water‐quality trends over the past 25 years (1998–2022) in Lake Washington, a well‐studied large lake in the Seattle metro area. The watershed population grew rapidly during that time (34% from 2000 to 2020), yet Lake Washington became substantially less eutrophic and indicators of development impacts stabilized or decreased. Chlorophyll concentrations during the main spring bloom decreased sharply (−25% per decade), and water clarity and near‐bottom dissolved oxygen both increased (8.5% and 17% per decade, respectively). Alkalinity and specific conductance had increased during the 1970s–1990s, but in recent decades, they held stable. Peak winter/spring nitrogen and phosphorus concentrations decreased (−4.9% and −5.6% per decade, respectively), indicating decreased watershed inputs. The type of development during this time was likely a key contributor: we found no net loss of forest area and little increase in developed land area (4.7% from 2001 to 2021). Instead of expanding into new areas, redevelopment increased density on already‐developed land and likely drove improvements in stormwater treatment and other environmental protections. Future work comparing stream watersheds could help discern which specific aspects of redevelopment helped reduce nutrients and other impacts. However, nutrient reductions were not the only factors controlling the lake's trophic state; chlorophyll decreased much more strongly than phosphorus did. Lake Washington is a complex ecosystem governed not only by water chemistry but also by interactions with physical and biological factors such as stratification, warming, phytoplankton community shifts, or food‐web interactions. A better understanding of all these factors is essential to provide sound scientific guidance and ensure that Lake Washington and other lakes can thrive in a growing city.

We have previously observed that methane supplied to lake sediment microbial communities as a substrate not only causes a response by bona fide methanotrophic bacteria, but also by non-methane-oxidizing bacteria, especially by members of the family Methylophilaceae. This result suggested that methane oxidation in this environment likely involves communities composed of different functional guilds, rather than a single type of microbe. To obtain further support for this concept and to obtain further insights into the factors that may define such partnerships, we carried out microcosm incubations with sediment samples from Lake Washington at five different oxygen tensions, while methane was supplied at the same concentration in each. Community composition was determined through 16S rRNA gene amplicon sequencing after 10 and 16 weeks of incubation. We demonstrate that, in support of our prior observations, the methane-consuming communities were represented by two major types: the methanotrophs of the family Methylococcaceae and by non-methanotrophic methylotrophs of the family Methylophilaceae. However, different species persisted under different oxygen tensions. At high initial oxygen tensions (150 to 225 µM) the major players were, respectively, species of the genera Methylosarcina and Methylophilus, while at low initial oxygen tensions (15 to 75 µM) the major players were Methylobacter and Methylotenera. These data suggest that oxygen availability is at least one major factor determining specific partnerships in methane oxidation. The data also suggest that speciation within Methylococcaceae and Methylophilaceae may be driven by niche adaptation tailored toward specific placements within the oxygen gradient.

We collected suspended particulate matter (seston) and zooplankton samples from Lake Washington in Seattle, Washington, USA, over a 10‐month period to investigate the effects of food availability on zooplankton fatty acid (FA) composition. The percentage of nutritionally critical ω3 polyunsaturated fatty acids (PUFA) in the seston varied from 8% of the FA pool in midsummer to 30% during the spring diatom bloom. Zooplankton accumulated much higher percentages ω3 PUFA than was available in the seston. In particular, cladocerans preferentially accumulated eicosapentaenoic acid (EPA, 20:5ω3), copepods accumulated docosahexaenoic acid (DHA, 22:6ω3), and both copepods and cladocerans accumulated 18 carbon chain ω3 PUFAs (C₁₈ ω3). By comparison, the FA of zooplanktivorous juvenile sockeye salmon (Oncorhynchus nerka) were strongly dominated by EPA (12.5% ± 2.1%) and DHA (28.2% ± 8.7%). The saturated fatty acid and the arachidonic acid (ARA, 20:4ω6) composition of Diaptomus ashlandi was strongly (r² = 0.76) and moderately (r² = 0.54) correlated with the prevalence of these FAs in the seston. Furthermore, the DHA content of Diaptomus was moderately correlated with the seston's DHA content (r² = 0.45) and very strongly correlated with seston EPA (r² = 0.89). Since EPA was the most prevalent PUFA in the seston and DHA was the most prevalent PUFA in Diaptomus, these results suggest that Diaptomus may synthesize DHA from the EPA in their food. In general, zooplankton species in Lake Washington were strongly enriched with those FA molecules that are most physiologically important for fish nutrition (i.e., ARA, EPA, and DHA), indicating a clear mechanism by which changes in seston composition influence fisheries ecology.

“ W. T. Edmondson has spent his career answering questions about the ecological impacts of human experiments on lakes in Washington State. In this volume, he recounts these studies and captures from his experiences a larger view of the nature of our environmental problems. . . . While the commentary is wide ranging, the foundation is a personal account of one ecologist’s lifetime experience on the dual points of research and public application of that research.”—Research and Exploration“W. T. Edmondson, a zoologist, extracts enduring lessons from his more than 50 years of experience in persuading political powers to make use of scientific knowledge when they set about drawing up laws for managing human interventions in the environment. Any scientist who follows in Edmondson’s footsteps should benefit from reading this sensitive recounting of political battles.”—Garrett Hardin, Pacific Northwest Quarterly

The role of methane in global warming has become paramount to the environment and the human society, especially in the past few decades. Methane cycling microbial communities play an important role in the global methane cycle, which is why the characterization of these communities is critical to understand and manipulate their behavior. Methanotrophs are a major player in these communities and are able to oxidize methane as their primary carbon source. Lake Washington is a freshwater lake characterized by a methane-oxygen countergradient that contains a methane cycling microbial community. Methanotrophs are a major part of this community involved in assimilating methane from lake water. Two significant methanotrophic species in this community are and . In this work, these methanotrophs are computationally studied via developing highly curated genome-scale metabolic models. Each model was then integrated to form a community model with a multi-level optimization framework. The competitive and mutualistic metabolic interactions among and were also characterized. The community model was next tested under carbon, oxygen, and nitrogen limited conditions in addition to a nutrient-rich condition to observe the systematic shifts in the internal metabolic pathways and extracellular metabolite exchanges. Each condition showed variations in the methane oxidation pathway, pyruvate metabolism, and the TCA cycle as well as the excretion of formaldehyde and carbon di-oxide in the community. Finally, the community model was simulated under fixed ratios of these two members to reflect the opposing behavior in the two-member synthetic community and in sediment-incubated communities. The community simulations predicted a noticeable switch in intracellular carbon metabolism and formaldehyde transfer between community members in sediment-incubated vs. synthetic condition. In this work, we attempted to predict the response of a simplified methane cycling microbial community from Lake Washington to varying environments and also provide an insight into the difference of dynamics in sediment-incubated microcosm community and synthetic co-cultures. Overall, this study lays the ground for in silico systems-level studies of freshwater lake ecosystems, which can drive future efforts of understanding, engineering, and modifying these communities for dealing with global warming issues.

Global change is leading to shifts in the seasonal timing of growth and maturation for primary producers. Remote sensing is increasingly used to measure the timing of primary production in both aquatic and terrestrial ecosystems, but there is often a poor correlation between these results and direct observations of life-history responses of individual species. One explanation may be that, in addition to phenological shifts, global change is also causing shifts in community composition among species with different seasonal timing of growth and maturation. We quantified how shifts in species phenology and in community composition translated into phenological change in a diverse phytoplankton community from 1962 to 2000. During this time, the aggregate community spring-summer phytoplankton peak has shifted 63 days earlier. The mean taxon shift was only 3 days earlier, and shifts in taxa phenology explained only 40% of the observed community phenological shift. The remaining community shift was attributed to dominant early-season taxa increasing in abundance while a dominant late-season taxon decreased in abundance. In diverse producer communities experiencing multiple stressors, changes in species composition must be considered to fully understand and predict shifts in the seasonal timing of primary production.

In many food webs, species in similar trophic positions can interact either by competing for resources or boosting shared predators (apparent competition), but little is known about how the relative strengths of these interactions vary across environmental gradients. Introduced Mysis diluviana shrimp interact with planktivorous fishes such as kokanee salmon (lacustrine Oncorhynchus nerka ) through both of these pathways, and effective management depends on understanding which interaction is more limiting under different conditions. An \"environmental matching\" hypothesis predicts the ecological impacts of Mysis are maximized under cool conditions near its thermal optimum. In addition, we hypothesized Mysis is more vulnerable to predation by lake trout in relatively shallow waters, and therefore Mysis enhances lake trout density and limits kokanee through apparent competition more strongly in shallower habitats. We tested whether these hypotheses could explain food web differences between two connected lake basins, one relatively shallow and the other extremely deep. The shallower basin warmed faster, thermally excluded Mysis from surface waters for 75% longer, and supported 2.5-18 times greater seasonal production of cladoceran zooplankton than the deeper basin, standardized by surface area. Mysis consumed 14-22% less zooplankton in the shallower basin, and lower ratios of total planktivore consumption to zooplankton production (C:P) indicated less potential for resource competition with kokanee, consistent with environmental matching. Lake trout diets contained more Mysis in the shallower basin and at shallower sampling sites within both basins. The catch rate of lake trout was seven times greater and the predation risk for kokanee was 4-5 times greater in the shallower basin than in the deeper basin, consistent with stronger apparent competition in shallower habitats. Understanding how the strengths of these interactions are mediated by temperature and depth would enable managers to select appropriate strategies to address the unique combinations of conditions in hundreds of affected systems.

Gram-positive methylotrophic bacteria have been known for a long period of time, some serving as model organisms for characterizing the specific details of methylotrophy pathways/enzymes within this group. However, genome-based knowledge of methylotrophy within this group has been so far limited to a single species, Bacillus methanolicus (Firmicutes). The paucity of whole-genome data for Gram-positive methylotrophs limits our global understanding of methylotrophy within this group, including their roles in specific biogeochemical cycles, as well as their biotechnological potential. Here, we describe the isolation of seven novel strains of Gram-positive methylotrophs that include two strains of Bacillus and five representatives of Actinobacteria classified within two genera, Arthrobacter and Mycobacterium. We report whole-genome sequences for these isolates and present comparative analysis of the methylotrophy functional modules within these genomes. The genomic sequences of these seven novel organisms, all capable of growth on methylated amines, present an important reference dataset for understanding the genomic basis of methylotrophy in Gram-positive methylotrophic bacteria. This study is a major contribution to the field of methylotrophy, aimed at closing the gap in the genomic knowledge of methylotrophy within this diverse group of bacteria.