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Tidal Echoes
Tidal Echoes is a literary and art journal that showcases the art and writing of Southeast Alaskans.
Recent Submissions
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Indigenous engagement with the Alexander Archipelago Wolf: Cultural context and traditional ecological knowledgeThe U.S. Fish and Wildlife Service in Alaska conducted a Species Status Assessment in response to a petition to list the Alexander Archipelago wolf under the Endangered Species Act. This federal undertaking could not be adequately prepared without including the voices of the Indigenous People who have a deep connection with the subspecies. The Indigenous knowledge presented in this report is the cultural and intellectual property of those who have shared it. The purpose of the report is to communicate the knowledge shared with us to the U.S. Fish and Wildlife Service to help inform the Species Status Assessment and future tribal consultations, wildlife research, and management. Due to a constrained regulatory timeline, we employed rapid appraisal research to expeditiously develop a preliminary understanding of Indigenous People’s ecological knowledge of wolves. We applied the social scientific methods of qualitative ethnography and inductive coding from grounded theory for text analysis. We conducted archival research and literature reviews on the cultural significance of wolves in Tlingit society and social organization to supplement in-depth conversations with traditional knowledge holders who are local wolf experts. The study was informed by two tribal consultations.
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American Museum of Natural History Educator's Guide: Northwest Coast HallWelcome to the Northwest Coast Hall. Reopened in 2022, it is the result of an intensive five-year collaboration between the Museum and ten advisors from the Indigenous cultural groups featured in the hall. This revitalized hall celebrates Indigenous worldview, artistry, cultural persistence, and the distinct practices and histories of the individual Nations along the Northwest Coast.
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Indigenous use and conservation of harbor seals (Phoca vitulina) at Yakutat, Alaska since the sixteenth centurySustainable Indigenous resource use reflects balance between animal populations and levels of human consumption, influenced by natural cycles of faunal abundance, community size and subsistence needs, procurement technologies, and the requirements of trade or commodity production. Sustainability is “epiphenomenal” when animal populations are preserved, and community needs met, without deliberate measures to prevent overharvesting. Alternatively, Indigenous conservation—cultural practices that moderate use of a resource to prevent its depletion—may play a determinative role. In this study from the Tlingit community of Yakutat, Alaska in the Northwest Coast cultural region, we interweave Indigenous and scientific perspectives to trace the use and conservation of harbor seals (Phoca vitulina) from before Western contact through the Russian and American colonial periods to the present. Harbor seals, which concentrate in large numbers at a summer ice floe rookery near Hubbard Glacier, are the community's most important subsistence food and a key to its culture and history. The Smithsonian Institution and Yakutat Tlingit Tribe undertook collaborative research in historical ecology and archaeology in 2011–2014 including oral interviews with elders and subsistence providers, excavations at sealing sites, archaeofaunal analysis, historical and archival research, and consideration of climate cycles and biological regime shifts that influence the harbor seal population in the Gulf of Alaska. We compare technologies and hunting practices before and after Western contact, estimate harvest levels in different periods, and evaluate the effectiveness of traditional conservation practices that included hunting quotas enforced by clan leaders and the seasonal delay of hunting with firearms to prevent abandonment of the rookery by the seal herd.
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Downstream passage performance of silver eel at an angled rack: Effects of behavior and morphologyThe European eel is critically endangered due to heavy impact of anthropogenic factors, such as habitat fragmentation, overexploitation and climate change. During downstream migration, silver eels may encounter hydropower plants, which often result in delay or mortality from impingement on trash-racks or turbine passage. These problems can be mitigated with downstream passage solutions, such as angled racks that guide downstream-migrating eels to safe passage routes. The importance of bar spacing and phenotypic diversity for passage performance is, however, largely unknown. In this study, we investigated how morphological parameters (body mass, eye and fin indices) and behavioral score (open field test) influenced passage rate at an experimental intake equipped with a bypass and angled racks with either 15 or 30 mm bar spacing. Both racks were efficient in guiding eels into a bypass. There was a strong positive effect of body mass and a weak positive effect of open field test score on passage rate. Other factors such as eye and fin indices played a minor role. These results demonstrate the performance of angled racks with bypasses and form a useful starting point for further research regarding the relationships between individual variation in behavior, morphology and passage solutions for silver eels.
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Optimizing seaweed biomass production ‑ A two kelp solutionInterest in farming kelps has grown beyond using kelp for food, feed or biofuels. There is considerable interest in generating biomass from seaweed for use in bioplastics and other products that would substitute for petroleum-derived products. For these uses to be viable, large amounts of biomass are needed. Very large kelp farms can be expensive to build and maintain, leading to the need to optimize the biomass per unit area. Although close spacing of growlines can lead to poor growth, a viable approach may be to grow two species of kelps together: one that hangs down and one that is buoyant, growing up. This system would increase the spacing in three dimensions. In Alaska, Saccharina latissima is commonly grown hanging down from longlines. One of the buoyant Alaskan kelps is Nereocystis luetkeana. Because there are commercial uses for wild-harvested Nereocystis in Alaska, we undertook a preliminary trial in Kodiak, Alaska, that grew both Saccharina and Nereocystis in the same longline array. Closely spaced lines were seeded the first week of February 2023 and set at 3 m below the surface. The arrays were harvested in late June 2023. Total yields were greatest on the combined arrays, followed by the Nereocystis only and Saccharina only arrays. Despite having 45% fewer grow-lines, the total yield of the Nereocystis on the combined arrays was statistically similar to the Nereocystis only arrays. These results may have significance for large scale macroalgal production.
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Reshaping research paradigms: Insights from a large-scale project based in Nunatsiavut, Labrador, CanadaArctic Institute of North America, 2024-09Across Inuit Nunangat (the Inuit homelands of Canada) researchers have been called to engage ethically and meaningfully with community members to develop projects that support local goals. This article focuses on understanding such engagement in the context of Nunatsiavut, an Inuit-governed territory in the province of Newfoundland and Labrador, Canada. In 2022 we conducted 27 interviews with researchers (both southern- and community-based), Inuit government representatives, and NGO representatives associated with the transdisciplinary SakKijânginnaKullugit Nunatsiavut Sivunitsangit (Sustainable Nunatsiavut Futures [SNF]) Project. SakKijânginnaKullugit Nunatsiavut Sivunitsangit began in 2020 and was designed, in part, to facilitate the co-production of knowledge between researchers and community members about climatic changes in Nunatsiavut. Through interviews, we explored what ethical and meaningful community engagement means in the context of a large-scale transdisciplinary project. Drawing on an analysis of interview data, we examine how project members and partners engage with Inuit community members, and how members of the project team who are Inuit have experienced these engagements. Based on participant responses, we identified elements needed for, and barriers to, ethical and meaningful engagement. We also heard about possible solutions. University researchers described institutional constraints to long-term engagement, while members of the Nunatsiavut Government staff and Inuit research coordinators emphasized that extractive (one-sided) forms of engagement can negatively impact communities. Interviewees described how a) restructuring academic and funding institutions, b) broadening engagement methods, and c) scaling down within a project can minimize the likelihood of negative effects and lead to more ethical and meaningful community engagement.
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A quasi-one-dimensional ice mélange flow model based on continuum descriptions of granular materialsField and remote sensing studies suggest that ice mélange influences glacier–fjord systems by exerting stresses on glacier termini and releasing large amounts of freshwater into fjords. The broader impacts of ice mélange over long timescales are unknown, in part due to a lack of suitable ice mélange flow models. Previous efforts have included modifying existing viscous ice shelf models, despite the fact that ice mélange is fundamentally a granular material, and running computationally expensive discrete element simulations. Here, we draw on laboratory studies of granular materials, which exhibit viscous flow when stresses greatly exceed the yield point, plug flow when the stresses approach the yield point, and exhibit stress transfer via force chains. By implementing the nonlocal granular fluidity rheology into a depth- and width-integrated stress balance equation, we produce a numerical model of ice mélange flow that is consistent with our understanding of well-packed granular materials and that is suitable for long-timescale simulations. For parallel-sided fjords, the model exhibits two possible steady-state solutions. When there is no calving of icebergs or melting of previously calved icebergs, the ice mélange is pushed down-fjord by the advancing glacier terminus, the velocity is constant along the length of the fjord, and the thickness profile is exponential. When calving and melting are included and treated as constants, the ice mélange evolves into another steady state in which its location is fixed relative to the fjord walls, the thickness profile is relatively steep, and the flow is extensional. For the latter case, the model predicts that the steady-state ice mélange buttressing force depends on the surface and basal melt rates through an inverse power-law relationship, decays roughly exponentially with both fjord width and gradient in fjord width, and increases with the iceberg calving flux. The buttressing force appears to increase with calving flux (i.e., glacier thickness) more rapidly than the force required to prevent the capsizing of full-glacier-thickness icebergs, suggesting that glaciers with high calving fluxes may be more strongly influenced by ice mélange than those with small fluxes.
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Influences on the Hematopoietic Stem Cell NicheHematopoietic Stem Cells (HSCs) are supported by the bone marrow microenvironment to maintain normal production of blood cells. The niche may be considered an “ecosystem” that support the function of HSCs and other supportive cells. Alterations in the bone marrow niche are commonly observed in hematologic malignancies. Here, we review recent insights into the location and the molecular and cellular components of the bone marrow niche. Moreover, we discuss how the niche interacts with HSCs to drive the pathogenesis of hematopoietic malignancies. Overall, a better understanding of the influences on the HSC niche may drive therapeutic development targeting defective and aberrant hematopoiesis.
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Therapeutic Potential of Ceramide in Cancer TreatmentCeramides are a family of wax-like lipids that fall under the broader category of sphingolipids. A ceramide is composed of a sphingosine side chain coupled to a fatty acid via an amide linkage. Distinct from complex sphingolipids, the head of ceramide is a simple alcohol rather than a phosphate, phosphocholine, sugar, or more. The fatty acid chains of ceramide can also vary in chain length and degree of saturation. The degree of saturation may determine the biological activity of the ceramide species. Ceramides are highly abundant within the cell membrane of eukaryotic cells and are appreciated for their structural roles in these cells. Moreover, ceramides are well known for their biological activity including as regulators of apoptosis, senescence, the cell cycle, and differentiation. This review discusses pathways of ceramide, roles of ceramide in various diseases, targeting ceramide metabolism in the treatment of cancer, as well as ceramide-delivering nanotechnologies.
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Obesity Promotes the Ceramide-Mediated NADPH Oxidase in Acute Myeloid LeukemiaAcute myeloid leukemia (AML) is a type of blood cancer of the myeloid cell lineage. Obesity is characterized by an increase in body weight that results in excessive fat accumulation. Obesity has been associated with an increased incidence of many cancers, including blood cancers. This study evaluated the role obesity in AML progression in a novel transgenic mouse model developed by crossing Flt3ITD mice with Lepob/ob mice. Leukemia burden was augmented in obese AML mice. In addition, it was determined that obesity upregulated the ceramide-mediated and ceramide-1-phosphate-mediated NADPH oxidase 2 (NOX2). Notably, increased oxidative pathways has been attributed to disease progression in AML. Taken together, this study demonstrates a direct link between obesity and the progression of AML in part by augmenting the ceramide mediated NOX2.
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Acute myeloid leukemia stratifies as 2 clinically relevant sphingolipidomic subtypesAcute myeloid leukemia (AML) is an aggressive, heterogeneous disease with genomic subtypes that are increasingly treated differently. There is a growing interest in going beyond mutations and cytogenetics to stratify AML. Recent work has combined proteomics,1 signaling,2,3 or immunophenotypes4 with integrated genomic-transcriptomic measurements to improve AML risk classifications.5 Although invaluable as resources, such approaches can neither extend retroactively to existing repositories nor prospectively to new AML cases lacking these data types. We sought to develop a more extensible approach involving sphingolipids (Figure 1A), a family of bioactive molecules implicated in AML pathogenesis and therapeutic resistance6,7 that differentially regulate cell proliferation,8 differentiation,9 autophagy,10 apoptosis,11 and immune cell activation.12 Sphingolipid abundances in AML vary heterogeneously and ratiometrically,13 prompting us to ask whether systematic sphingolipidomic profiling could meaningfully stratify patients with AML and common AML cell lines.
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Alaska’s Flora as a Treatment for CancerCancer is an extraordinarily complex illness, with many tumors ultimately developing resistance to the currently available therapeutics. This highlights a need for the discovery of new anticancer medicines. Natural products have been utilized for centuries by the indigenous people of Alaska for both spiritual and medicinal purposes and have traditionally been administered as medicine for a wide range of ailments from the common cold to cancer. These plants, including Devil’s club, Labrador tea, Western skunk cabbage, and various species of wild berries such as blueberries, lingonberries, salmonberries, and high-bush cranberries, contain a wide variety of natural compounds with therapeutic potential. Various anthocyanins and polyphenols, including quercetin, as well as the pentacyclic triterpenoid ursolic acid, have been identified in these medicinal plants and have demonstrated antioxidant, anti-inflammatory, and anticancer activity. These ethnobotanicals and the unique compounds found within may be integral to the development of novel therapeutics for the treatment of cancer and other conditions.
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Gradients of deposition and in situ production drive Global glacier organic matter compositionRunoff from rapidly melting mountain glaciers is a dominant source of riverine organic carbon in many high-latitude and high-elevation regions. Glacier dissolved organic carbon is highly bioavailable, and its composition likely reflects internal (e.g., autotrophic production) and external (i.e., atmospheric deposition) sources. However, the balance of these sources across Earth's glaciers is poorly understood, despite implications for the mineralization and assimilation of glacier organic carbon within recipient ecosystems. We assessed the molecular-level composition of dissolved organic matter from 136 mountain glacier outflows from 11 regions covering six continents using ultrahigh resolution 21 T mass spectrometry. We found substantial diversity in organic matter composition with coherent and predictable (80% accuracy) regional patterns. Employing stable and radiocarbon isotopic analyses, we demonstrate that these patterns are inherently linked to atmospheric deposition and in situ production. In remote regions like Greenland and New Zealand, the glacier organic matter pool appears to be dominated by in situ production. However, downwind of industrial centers (e.g., Alaska and Nepal), fossil fuel combustion byproducts likely underpin organic matter composition, resulting in older and more aromatic material being exported downstream. These findings highlight that the glacier carbon cycle is spatially distinct, with ramifications for predicting the dynamics and fate of glacier organic carbon concurrent with continued retreat and anthropogenic perturbation.
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Forecasted changes to the timing of Pacific herring Clupea pallasii spawn in a warming oceanPacific herring Clupea pallasii are a critical commercial and subsistence fish species and play a keystone role in the ecology and culture of the North Pacific. The annual herring spawn, in which mature herring migrate nearshore to deposit eggs along the coastline, is an important event linked to the migration of seabirds and marine mammals as well as a subsistence harvest for Alaska Natives and First Nations in British Columbia. Previous work has suggested that environmental variables and broad teleconnection indices play a role in the magnitude and phenology of spawning; however, the effects of these drivers have not been examined in the context of future climate scenarios. Here, we modeled variability in the timing of herring spawn across British Columbia and Southeast Alaska using survey data from 1951-2022. We created a model using Pacific teleconnection indices, sea surface temperature (SST), tidal height, and lagged data to predict spawn date anomalies (SDAs) across 9 spawning regions. SDAs were significantly affected by the Oceanic Niño Index, Pacific Decadal Oscillation, SST, and lagged SDAs. We then used this model to predict SDAs using projected SST from climate models and bootstrapped teleconnection data from 2025-2100. Future herring spawn timing trends earlier on average with warming SSTs, although the magnitude is relatively small, occurring 9 d earlier on average by 2100. This changing phenology, though small, varied by region and may have ecosystem-level ramifications and create timing mismatch for migratory species. However, our findings also reinforce the importance of other physical factors not measured in this study, such as photoperiod, which drive herring spawn timing.
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Clam Size Explains Some Variability in Paralytic Shellfish Toxin Concentrations in Butter Clams (Saxidomus gigantea) in Southeast AlaskaHarmful algal blooms (HABs) are a reoccurring threat to subsistence and recreational shellfish harvest in Southeast Alaska. Recent Tribally led monitoring programs have enhanced understanding of the environmental drivers and toxicokinetics of shellfish toxins in the region; however, there is considerable variability in shellfish toxins in some species, which cannot be easily explained by seasonal bloom dynamics. Persistent concentrations of paralytic shellfish toxins (PSTs) in homogenized butter clam samples (n > 6, Saxidomus gigantea) have been observed in several communities, and relatively large spikes in concentrations are sometimes seen without Alexandrium observations or increased toxin concentrations in other species. In order to investigate potential sources of variability in PST concentrations from this subsistence species, we assessed individual concentrations of PSTs across a size gradient of butter clams during a period of relatively stable PST concentrations. We found that increasing concentrations of PSTs were significantly associated with larger clams using a log-linear model. We then simulated six clams randomly sampled from three size distributions, and we determined large clams had an outsized probability of contributing a significant proportion of the total toxicity in a six-clam homogenized sample. While our results were obtained during a period of low HAB activity and cannot be extrapolated to periods of intoxication or rapid detoxification, they have significant ramifications for both monitoring programs as well as subsistence and recreational harvesters.
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Advancing an integrated understanding of land–ocean connections in shaping the marine ecosystems of coastal temperate rainforest ecoregionsLand and ocean ecosystems are strongly connected and mutually interactive. As climate changes and other anthropogenic stressors intensify, the complex pathways that link these systems will strengthen or weaken in ways that are currently beyond reliable prediction. In this review we offer a framework of land–ocean couplings and their role in shaping marine ecosystems in coastal temperate rainforest (CTR) ecoregions, where high freshwater and materials flux result in particularly strong land–ocean connections. Using the largest contiguous expanse of CTR on Earth—the Northeast Pacific CTR (NPCTR)—as a case study, we integrate current understanding of the spatial and temporal scales of interacting processes across the land–ocean continuum, and examine how these processes structure and are defining features of marine ecosystems from nearshore to offshore domains. We look ahead to the potential effects of climate and other anthropogenic changes on the coupled land–ocean meta-ecosystem. Finally, we review key data gaps and provide research recommendations for an integrated, transdisciplinary approach with the intent to guide future evaluations of and management recommendations for ongoing impacts to marine ecosystems of the NPCTR and other CTRs globally. In the light of extreme events including heatwaves, fire, and flooding, which are occurring almost annually, this integrative agenda is not only necessary but urgent.
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An analytical approach for simulating effects of avalanches on mountain goat population dynamics: Implications for management and conservationMountain environments with snow avalanche hazard cover about 6% of Earth’s land area and occur on all continents. Whereas human risks associated with avalanche hazard have been widely studied, little is known about how avalanche activity affects population dynamics in mountain wildlife. Globally, 32 species of mountain ungulates across 70 countries occupy avalanche-prone terrain. Avalanches comprise the leading cause of mortality in coastal Alaskan mountain goats (mean = 36%, range = 23 - 65%, depending on area), and disproportionately remove prime-aged individuals from populations. The implications of such rates and patterns of mortality on population growth rate are likely to be significant given the species’ low reproductive productivity, but further clarity is needed. To fill this knowledge gap, we developed a sex- and age-specific population modeling approach that integrates both reproduction and mortality to simulate the effects of avalanche-caused mortality on population growth rate across a range of empirically-observed states of avalanche-caused mortality (minimum, mean, maximum). Simulations were conducted to illustrate model functionality, and also provide insight about potential avalanche impacts on population demographic processes. For example, when severe avalanche years occur populations can experience significant additive mortality and declines (up to 15%). Due to low reproductive rates and slow life-history strategy of the species, such impacts can lead to long demographic recovery times (up to 11 years). From a species conservation perspective, such impacts are striking, and highlight the utility of employing a quantitative modeling approach to predict possible effects of avalanches on mountain ungulate population dynamics and viability. Our work explicitly builds upon recent findings about the importance of avalanches on mountain-adapted animal populations, and associated implications for the cultural and ecological communities that depend on them.
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Seasonal patterns in riverine carbon form and export from a temperate forested watershed in Southeast AlaskaRiverine export of carbon (C) is an important part of the global C cycle; however, most riverine C budgets focus on individual forms of C and fail to comprehensively measure both organic and inorganic C species in concert. To address this knowledge gap, we conducted high frequency sampling of multiple C forms, including dissolved organic C (DOC), inorganic carbon (as alkalinity), particulate organic C (POC), coarse particulate organic C (CPOC), and invertebrate biomass C across the main run-off season in a predominantly rain-fed watershed in Southeast Alaska. Streamwater concentrations were used to model daily watershed C export from May through October. Concentration and modeled yield data indicated that DOC was the primary form of riverine C export (8708 kg C/km2), except during low flow periods when alkalinity (3125 kg C/km2) was the dominant form of C export. Relative to DOC and alkalinity, export of particulate organic C (POC: 992 kg C/km2; CPOC: 313 kg C/km2) and invertebrates (40 kg C/km2) was small, but these forms of organic matter could disproportionately impact downstream food webs because of their higher quality, assessed via C to nitrogen ratios. These seasonal and flow driven changes to C form and export likely provide subsidies to downstream and nearshore ecosystems such that predicted shifts in regional hydroclimate could substantially impact C transfer and incorporation into aquatic food webs.
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The relationship between submarine melt and subglacial discharge from observations at a tidewater glacierAt tidewater glacier termini, ocean-glacier interactions hinge on two sources of freshwater—submarine melt and subglacial discharge—yet these freshwater fluxes are often unconstrained in their magnitude, seasonality, and relationship. With measurements of ocean velocity, temperature and salinity, fjord budgets can be evaluated to partition the freshwater flux into submarine melt and subglacial discharge. We apply these methods to calculate the freshwater fluxes at LeConte Glacier, Alaska, across a wide range of oceanic and atmospheric conditions during six surveys in 2016–2018. We compare these ocean-derived fluxes with an estimate of subglacial discharge from a surface mass balance model and with estimates of submarine melt from multibeam sonar and autonomous kayaks, finding relatively good agreement between these independent estimates. Across spring, summer, and fall, the relationship between subglacial discharge and submarine melt follows a scaling law predicted by standard theory (melt ∼ discharge1/3), although the total magnitude of melt is an order of magnitude larger than theoretical estimates. Subglacial discharge is the dominant driver of variability in melt, while the dependence of melt on fjord properties is not discernible. A comparison of oceanic budgets with glacier records indicates that submarine melt removes 33%–49% of the ice flux into the terminus across spring, summer, and fall periods. Thus, melt is a significant component of the glacier's mass balance, and we find that melt correlates with seasonal retreat; however, melt does not appear to directly amplify calving.
