Projecting the Hydrologic Impacts of Climate Change on Montane Wetlands

Wetlands are globally important ecosystems that provide critical services for natural communities and human society. Montane wetland ecosystems are expected to be among the most sensitive to changing climate, as their persistence depends on factors directly influenced by climate (e.g. precipitation, snowpack, evaporation). Despite their importance and climate sensitivity, wetlands tend to be understudied due to a lack of tools and data relative to what is available for other ecosystem types. Here, we develop and demonstrate a new method for projecting climate-induced hydrologic changes in montane wetlands. Using observed wetland water levels and soil moisture simulated by the physically based Variable Infiltration Capacity (VIC) hydrologic model, we developed site-specific regression models relating soil moisture to observed wetland water levels to simulate the hydrologic behavior of four types of montane wetlands (ephemeral, intermediate, perennial, permanent wetlands) in the U. S. Pacific Northwest. The hybrid models captured observed wetland dynamics in many cases, though were less robust in others. We then used these models to a) hindcast historical wetland behavior in response to observed climate variability (1916–2010 or later) and classify wetland types, and b) project the impacts of climate change on montane wetlands using global climate model scenarios for the 2040s and 2080s (A1B emissions scenario). These future projections show that climate-induced changes to key driving variables (reduced snowpack, higher evapotranspiration, extended summer drought) will result in earlier and faster drawdown in Pacific Northwest montane wetlands, leading to systematic reductions in water levels, shortened wetland hydroperiods, and increased probability of drying. Intermediate hydroperiod wetlands are projected to experience the greatest changes. For the 2080s scenario, widespread conversion of intermediate wetlands to fast-drying ephemeral wetlands will likely reduce wetland habitat availability for many species

Amyloid-beta/Fyn–Induced Synaptic, Network, and Cognitive Impairments Depend on Tau Levels in Multiple Mouse Models of Alzheimer’s Disease

Alzheimer\u27s disease (AD), the most common neurodegenerative disorder, is a growing public health problem and still lacks effective treatments. Recent evidence suggests that microtubule-associated protein tau may mediate amyloid-β peptide (Aβ) toxicity by modulating the tyrosine kinase Fyn.Weshowed previously that tau reduction prevents, and Fyn overexpression exacerbates, cognitive deficits in human amyloid precursor protein (hAPP) transgenic mice overexpressing Aβ. However, the mechanisms by which Aβ, tau, and Fyn cooperate in AD-related pathogenesis remain to be fully elucidated. Here we examined the synaptic and network effects of this pathogenic triad. Tau reduction prevented cognitive decline induced by synergistic effects of Aβ and Fyn. Tau reduction also prevented synaptic transmission and plasticity deficits in hAPP mice. Using electroencephalography to examine network effects, we found that tau reduction prevented spontaneous epileptiform activity in multiple lines of hAPP mice. Tau reduction also reduced the severity of spontaneous and chemically induced seizures in mice overexpressing both Aβ and Fyn. To better understand these protective effects, we recorded wholecell currents in acute hippocampal slices from hAPP mice with and without tau. hAPP mice with tau had increased spontaneous and evoked excitatory currents, reduced inhibitory currents, and NMDA receptor dysfunction. Tau reduction increased inhibitory currents and normalized excitation/inhibition balance and NMDA receptor-mediated currents in hAPP mice. Our results indicate that Aβ, tau, and Fyn jointly impair synaptic and network function and suggest that disrupting the copathogenic relationship between these factors could be of therapeutic benefit

A review of carbon monitoring in wet carbon systems using remote sensing

Carbon monitoring is critical for the reporting and verification of carbon stocks and change. Remote sensing is a tool increasingly used to estimate the spatial heterogeneity, extent and change of carbon stocks within and across various systems. We designate the use of the term wet carbon system to the interconnected wetlands, ocean, river and streams, lakes and ponds, and permafrost, which are carbon-dense and vital conduits for carbon throughout the terrestrial and aquatic sections of the carbon cycle. We reviewed wet carbon monitoring studies that utilize earth observation to improve our knowledge of data gaps, methods, and future research recommendations. To achieve this, we conducted a systematic review collecting 1622 references and screening them with a combination of text matching and a panel of three experts. The search found 496 references, with an additional 78 references added by experts. Our study found considerable variability of the utilization of remote sensing and global wet carbon monitoring progress across the nine systems analyzed. The review highlighted that remote sensing is routinely used to globally map carbon in mangroves and oceans, whereas seagrass, terrestrial wetlands, tidal marshes, rivers, and permafrost would benefit from more accurate and comprehensive global maps of extent. We identified three critical gaps and twelve recommendations to continue progressing wet carbon systems and increase cross system scientific inquiry

Serotonin 3A Receptor Subtype as an Early and Protracted Marker of Cortical Interneuron Subpopulations

To identify neocortical neurons expressing the type 3 serotonergic receptor, here we used transgenic mice expressing the enhanced green fluorescent protein (GFP) under the control of the 5-HT3A promoter (5-HT3A:GFP mice). By means of whole-cell patch-clamp recordings, biocytin labeling, and single-cell reversed-transcriptase polymerase chain reaction on acute brain slices of 5-HT3A:GFP mice, we identified 2 populations of 5-HT3A-expressing interneurons within the somatosensory cortex. The first population was characterized by the frequent expression of the vasoactive intestinal peptide and a typical bipolar/bitufted morphology, whereas the second population expressed predominantly the neuropeptide Y and exhibited more complex dendritic arborizations. Most interneurons of this second group appeared very similar to neurogliaform cells according to their electrophysiological, molecular, and morphological properties. The combination of 5-bromo-2-deoxyuridine injections with 5-HT3A mRNA detection showed that cortical 5-HT3A interneurons are generated around embryonic day 14.5. Although at this stage the 5-HT3A receptor subunit is expressed in both the caudal ganglionic eminence and the entopeduncular area, homochronic in utero grafts experiments revealed that cortical 5-HT3A interneurons are mainly generated in the caudal ganglionic eminence. This protracted expression of the 5-HT3A subunit allowed us to study specific cortical interneuron populations from their birth to their final functional phenotype

Pharmacological Analysis of Ionotropic Glutamate Receptor Function in Neuronal Circuits of the Zebrafish Olfactory Bulb

Although synaptic functions of ionotropic glutamate receptors in the olfactory bulb have been studied in vitro, their roles in pattern processing in the intact system remain controversial. We therefore examined the functions of ionotropic glutamate receptors during odor processing in the intact olfactory bulb of zebrafish using pharmacological manipulations. Odor responses of mitral cells and interneurons were recorded by electrophysiology and 2-photon Ca2+ imaging. The combined blockade of AMPA/kainate and NMDA receptors abolished odor-evoked excitation of mitral cells. The blockade of AMPA/kainate receptors alone, in contrast, increased the mean response of mitral cells and decreased the mean response of interneurons. The blockade of NMDA receptors caused little or no change in the mean responses of mitral cells and interneurons. However, antagonists of both receptor types had diverse effects on the magnitude and time course of individual mitral cell and interneuron responses and, thus, changed spatio-temporal activity patterns across neuronal populations. Oscillatory synchronization was abolished or reduced by AMPA/kainate and NMDA receptor antagonists, respectively. These results indicate that (1) interneuron responses depend mainly on AMPA/kainate receptor input during an odor response, (2) interactions among mitral cells and interneurons regulate the total olfactory bulb output activity, (3) AMPA/kainate receptors participate in the synchronization of odor-dependent neuronal ensembles, and (4) ionotropic glutamate receptor-containing synaptic circuits shape odor-specific patterns of olfactory bulb output activity. These mechanisms are likely to be important for the processing of odor-encoding activity patterns in the olfactory bulb

Reconstructing the past and modeling the future of wetland dynamics under climate change

Thesis (Ph.D.)--University of Washington, 2017-06Abstract Reconstructing the past and modeling the future of wetland dynamics under climate change Meghan Halabisky Chair of Supervisory Committee: Dr. L. Monika Moskal School of Environmental and Forest Sciences Wetland ecosystems are widely considered to be highly sensitive to climate change. However, scientific capacity to model climate impacts to wetlands has been hampered by the lack of accurate maps showing the spatial distribution of wetlands and data on their historical hydrological dynamics. Though these data may exist for particular wetlands, there are no broad scale datasets of wetland location and long-term hydrological dynamics. Remote sensing has been an important vehicle for mapping change to wetlands, but generally at spatial or temporal scales that do not capture the variability necessary for linking climate to wetland hydrodynamics. This data limitation and lack of methods have restricted research on how changes in climate will impact wetland hydrology to explorations of limited scope. The goal of this PhD was to characterize and model historic and future climate impacts to dynamics of wetland hydrology (i.e. inundation quantity, frequency, timing and duration) across the Columbia Plateau ecoregion. To achieve this goal, I developed new remote sensing methods to map and reconstruct wetland dynamics for thousands of individual wetlands at finer temporal and spatial resolutions than previously available (Chapter 1 and 2). In Chapter 1, I combined high-resolution aerial photographic imagery and a time series of Landsat satellite imagery to reconstruct wetland inundation patterns for individual wetlands from 1984 – 2011 in Douglas County, WA, USA. A key component of this method was the ability to measure fine scale changes (<30m) in surface water area using a sub-pixel technique called spectral mixture analysis. In Chapter 2, I adapted these methods so they could be scaled up to large extents without the computer processing requirements and technical challenges of using aerial imagery. In order to do this, I identified wetlands, not from the spectral and spatial characteristics one can derive out of aerial imagery as in Chapter 1, but instead using their temporal pattern of flooding and drying derived from the time series of Landsat satellite imagery. Using the methods developed in Chapter 1 and Chapter 2, I mapped and reconstructed wetland hydrodynamics for wetlands in the Columbia Plateau ecoregion, far surpassing any existing measurements of wetland hydrology in sample size (n= 5,382), temporal richness (~ 23 days), and temporal extent (27 years). Finally, in Chapter 3 I used this novel dataset to map changes in wetland hydrology across the Columbia Plateau identifying areas undergoing change. Additionally, I developed wetland-specific regression models to understand the relationship between climate and wetland hydrology, which I used to forecast changes to wetland hydrology under climate change. Beyond the technical analyses, an additional important part of the process for Chapter 3 was working with wetland practitioners from start to finish to ensure the data developed is both useful and used. The findings of this research suggest that wetlands in the Columbia Plateau are hydrologically variable with each wetland falling along a continuum from those driven primarily by surface water (i.e. precipitation, evaporation, and surface runoff) to those driven primarily by deep groundwater sources. The location of each wetland along this continuum, which I was able to approximate, varies greatly throughout the region, but follows a defined spatial pattern related to underlying geologic processes. Where a wetland falls along the groundwater to surface water continuum largely determined historical changes in inundation levels and how a wetland will respond in the future under climate change. In general, water levels in groundwater driven wetlands have typically decreased since 1984, whereas water levels in surface water driven wetlands have increased or stayed at similar levels over the same period. However, under the climate change scenario selected (ECHAM5 A1B) the results from the wetland-specific regression models suggest that groundwater driven wetlands will increase in water levels and dry less frequently. On the other end of the wetland continuum, surface water wetlands will decrease in surface water levels, dry more frequently, dry earlier in the season, or have little change. The results of this PhD provide an example of how remote sensing can deliver the fine scale detail and broad temporal and spatial extent necessary to model complex ecosystem dynamics. This knowledge is being used to inform the development of strategies to conserve the biodiversity supported by these systems, and prioritize and help stratify wetlands for further study and conservation action in the Columbia Plateau