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Behnke, Megan
Postdoctoral Researcher, Alaska Coastal Rainforest Center -
Bergstrom, Carolyn A.
Carolyn Bergstrom, Ph. D. is Professor of Marine Biology. -
Powell, James E.
Term Assistant Research Professor, Alaska Coastal Rainforest Center. Emeritus Professor, UAS. -
Sandoval, Artemio
Artemio is a UAS Alumus and Composer -
Whitney, Emily J.
Research Professional at the Alaska Coastal Rainforest Center
Recent Submissions
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Snow avalanches and the impact of climate‐linked extreme events on mountain wildlife population dynamics and resilienceClimate is changing rapidly in mountain environments, giving rise to increasing variability in weather, incidence of extremeevents, and alteration of the cryosphere. Natural hazards, such as snow avalanches, and the ecological communities they impactmay be particularly sensitive to such change. While avalanches may impose both ‘good’ and ‘bad’ effects on mountain ecosys-tems, the direct impacts that lead to mortality have particularly important implications for future viability and resilience ofslow-growing alpine wildlife populations. Here, we studied a sentinel species of coastal Alaskan mountain environments—themountain goat (Oreamnos americanus) – using long-term field data from individually marked animals (600 individuals over44 years) in a quantitative modeling framework to understand how avalanches influence demographic processes. Specifically, wedeveloped and parameterized a sex- and age-specific population modeling approach to simulate the effects of avalanche-causedmortality on population growth rate (λ). We examined a range of ecologically relevant scenarios based on empirically observedstates of avalanche-caused mortality. During years when avalanche impacts are severe, populations can experience significantadditive mortality and population declines (up to 15%). Due to low reproductive rates, such impacts can lead to long demographicrecovery times (up to 11 years, or ~1.5 mountain goat generations). Thus, during the course of a typical mountain goat lifetime,significant avalanche-linked perturbations can be expected to occur, suggesting that meaningful demographic signatures of av-alanche impacts are generationally recurrent and routinely imbedded in population histories. From a conservation perspective,such impacts are striking and highlight the utility of employing a quantitative modeling approach to predict possible effects ofavalanches and extreme events more broadly on mountain ungulate population dynamics and viability. Our work explicitlybuilds upon recent findings about the importance of avalanches on mountain-adapted animal populations and has implicationsfor the cultural and ecological communities that depend on them.
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The art of compassion: how viewing art affects prosocial intentionsArt functions as a communicative medium that evokes emotion and fosters social connection potentially motivating prosocial behavior. Grounded in theories of elevation and social cognition, this research investigated whether viewing art, regardless of its thematic content, would influence compassionate intentions toward individuals across varying relational distances (self, friend, stranger). The studies also examined if the types of imagined compassionate actions, categorized by expressive modalities (Chapman’s Love Languages, Gestures of Kindness, and Hedonic Pleasures), varied with relational closeness. Study 1 found that compassion-themed art influenced compassionate intentions toward strangers, with artistic communication predicting these intentions more strongly than explicit compassion messaging. Study 2 demonstrated that elevation, elicited by non-compassion-themed art, predicted compassionate intentions, particularly toward strangers. Across both studies, participants envisioned more intimate, close-proximity actions toward relationally close others. These findings indicate that art functions as a socially meaningful stimulus, activating emotional and cognitive mechanisms that support context-sensitive prosociality.
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Community-based, culturally relevant STEM: Engaging rural and Indigenous students through partnerships, institutional flexibility, and One HealthRural and Indigenous students face many barriers to persistence in biomedical and STEM trajectories including poor access to science experiences, a dearth of relatable educational resources, and educational structures misaligned with rural and Indigenous student and community needs. Rural Alaska Students in One Health Research (RASOR) is designed to provide a positive first college experience for rural and Indigenous students. Key innovations include 1) a partnership between the University of Alaska and tribal governments to allow for culturally relevant, locallymentored research experiences and 2) a customizable program structure. We also surveyed adults in the region regarding attitudes about science, its community relevance, and science opportunities for young people. One Health—the connection of human, animal, and environmental health—resonated with both adults and students. Student interest in both animal/environmental and human research increased during RASOR, as did measures of science self-efficacy, identity, and science aspirations. Community members view science as important and strongly support students’ scientific interests. However, perceptions remain that science training results in students leaving their communities, despite tribal leadership efforts to “grow-theirown” STEM opportunities and professionals in these same communities. We suggest One Health is a culturally meaningful pathway to promote engagement of rural and Indigenous students in biomedical and STEM fields and is enhanced by educator and institutional flexibility and community partnership.
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Calving as a source of acute and persistent kinetic energy to enhance submarine melting of tidewater glaciersCalving icebergs at tidewater glaciers release large amounts of potential energy. This energy—in principle—could be a source for submarine melting, which scales with near‐terminus water temperature and velocity. Because near‐terminus currents are challenging to observe or predict, submarine melt remains a key uncertainty in projecting tidewater glacier retreat and sea level rise. Here, we study one submarine calving event at Xeitl Sít’ (LeConte Glacier), Alaska, to explore the effect of calving on ice melt, using a suite of autonomously deployed instruments beneath, around, and downstream of the calving iceberg. Our measurements captured flows exceeding 5 m/s and demonstrate how potential energy converts to kinetic energy (EK). While most energy decays quickly (through turbulence, mixing, and radiated waves), near‐terminus EK remains elevated, nearly doubling predicted melt rates for hours after the event. Calving-induced currents could thus be an important overlooked energy source for submarine melt and glacier retreat.
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Fine-scale variability in iceberg velocity fields and implications for an ice-associated pinnipedIcebergs found in proglacial fjords serve as important habitats for pinnipeds in polar and subpolar regions. Environmental forcings can drive dramatic changes in the overall reduction in ice coverage across fjords in the circumpolar regions, with implications for pinnipeds that use ice for critical life-history functions, including pupping and molting. To better understand how pinnipeds respond to changes in iceberg habitat, we combine (i) iceberg velocity fields over hourly to monthly timescales, derived from high-rate time-lapse photogrammetry of Johns Hopkins Glacier and Inlet, Alaska, with (ii) aerial photographic surveys of harbor seals (Phoca vitulina richardii) conducted during the pupping (June) and molting (August) seasons. Iceberg velocities typically followed a similar diurnal pattern: flow was weak and variable in the morning and strong and unidirectional in the afternoon. The velocity fields tended to be highly variable in the inner fjord across a range of timescales due to changes in the strength and location of the subglacial outflow, whereas, in the outer fjord, the flow was more uniform, and eddies consistently formed in the same locations. During the pupping season, seals were generally more dispersed across the slow-moving portions of the fjord (with iceberg speeds of < 0:2 ms−1). In contrast, during the molting season, the seals were increasingly likely to be found on fastmoving icebergs in or adjacent to the glacier outflow plume. The use of slow-moving icebergs during the pupping season likely provides a more stable ice platform for nursing, caring for young, and avoiding predators. Periods of strong glacier runoff and/or katabatic winds may result in more dynamic and less stable ice habitats, with implications for seal behavior and distribution within the fjord.
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Laboratory experiments reveal transient fluctuations in ice mélange velocity and stress during periods of quasistatic flowAccurately predicting Greenland's ice mass loss is crucial for understanding future sea level rise. Approximately 50% of the mass loss results from iceberg calving at the ice-ocean interface. Ice mélange, a jammed, buoyant granular material that extends for 10 km or more in Greenland's largest fjords, can inhibit iceberg calving and discharge by transmitting shear stresses from fjord walls to glacier termini. Direct measurements of these resistive force dynamics are not possible in the field, thus, we created a scaled-down laboratory experiment to study jammed-packed ice mélange mechanics. We recorded videos of the mélange surface motion and subsurface profile during slow, quasistatic flow through a rectangular fjord, and recorded the total force on a model glacier terminus. When the wall friction is low, the ice mélange moves as a solid plug with little or no particle rearrangements. When the wall friction is larger than the internal friction, shear zones develop near the walls, and the buttressing force magnitude and fluctuations increase significantly. Associated discrete particle simulations illustrate the internal flow in both regimes. We also compare our experimental results to a continuum, depth-averaged model of ice mélange and find that the thickness of the mélange at the terminus provides a good indicator of the net buttressing force. However, the continuum model cannot capture the stochastic nature of the rearrangements and concomitant fluctuations in the buttressing force. These fluctuations may be important for short-time and seasonal controls on iceberg calving rates in fjords with thick and persistent ice mélange.
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Assessing Alaska's top-4 primary and ranked choice voting electoral reform: More moderate winners, more moderate policyIn recent years, ranked choice voting (RCV) has emerged as a leading electoral reform, often in combination with moves to open up primaries in order to increase voter choice and select more widely-supported representatives. Both nonpartisan primaries and RCV general elections have attracted advocacy from those seeking solutions to democratic malaise and polarization, and been introduced in different forms in several states. Despite this, only one legislature across the country has ever been elected under this model: the 2022 Alaskan State legislature, which combined a Top-4 nonpartisan primary with an RCV election. We assess the impact of this reform via ‘before and after’ case studies of individual electoral (re)matches, a survey of candidate ideological and policy positions, and examination of legislative coalitions. This research design allows us to isolate the impact of Top 4/RCV compared to the former model of closed party primaries and plurality general elections. We show that Alaska’s new electoral system provided more choice for voters and appears to have driven changes in both electoral outcomes and public policy. Despite more extremists standing for election post-reform, winning candidates were more likely to be centrists willing to work across the aisle and espouse moderate policy positions than prior to the reform.
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On a roll? or Is it a slide? Alaska's budgeting process in 2024As in 2023, Alaska’s politics seem to be benefitting from a more moderate and collegial policymaking environment and possibly even more sensible budgetary policy. In part, this seems due to Alaska’s adoption of a new election system which in 2022 generated a more moderate set of legislative coalitions than the previous several election cycles. These moderate coalitions may be short-lived, however, as an effort to repeal the new election system is underway. And even with our relatively moderate State House and State Senate coalitions, headwinds and controversies remain, especially issues around public education funding.
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Impact of multiple climate stressors on early life stages of North Pacific kelp speciesThis study examines the effects on bull kelp (Nereocystis luetkeana) and ribbon kelp (Alaria marginata) of combinations of three climate-related stressors relevant to high-latitude kelp forests: temperature, salinity, and sediment load. Fertile specimens of both species were collected from Juneau, Alaska. Spores produced were cultivated over 40 days in four ecologically relevant stressor treatments: control (all stressor levels normal; CTRL), increased glacial melt (normal temperature, low salinity, high sediment load; GLAC), increased runoff (high temperature, low salinity, normal sediment load; MELT) and climate change (high temperature, low salinity, high sediment load; CLIM). Gametophyte density in both species was reduced in treatments involving high sediment load. Gametophyte density in bull kelp was also reduced in the increased runoff treatment, while ribbon kelp appeared resilient. Gametophytes of A. marginata grew equally in the increased glacial melt treatment as in the control and exhibited some growth in the increased runoff treatment. Conversely, gametophytes of N. luetkeana exhibited low growth in all treatments other than the control. A large number of gametophytes of both species were unidentifiable as either male or female in high-temperature treatments. This likely had impacts on reproduction, as neither species was able to produce eggs or sporophytes in these treatments. The results presented here show that both N. luetkeana (a subtidal canopy-former) and A. marginata (an intertidal subcanopy species) are sensitive to combinations of thermal, hyposaline, and sediment stress. This may have an impact on the development of gametophytes and successful reproduction in these species and may therefore have implications for the ongoing persistence of wild kelp populations in future ocean conditions.
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Ocean acidification decreases molting but not survival of Antarctic amphipods Djerboa furcipes, Gondogeneia antarctica, and Prostebbingia gracilisOcean acidification refers to a decrease in the pH of the world’s oceans from the oceanic uptake of human-derived atmospheric CO2. Low pH is known to decrease the calcification and survival of many calcifying invertebrates. Shallow, hard bottom communities along the Western Antarctic Peninsula often have incredibly large numbers of invertebrate mesograzers that shelter on and are mutualists with the dominant brown macroalgae. The common amphipod species Djerboa furcipes, Gondogeneia antarctica, and Prostebbingia gracilis were collected from the immediate vicinity of Palmer Station, Antarctica (64°46′S, 64°03′W) in January–February 2023 and maintained under three different pH treatments simulating ambient conditions (approximately pH 8.0), near-future conditions for 2100 (pH 7.7), and distant future conditions (pH 7.3) for 8 weeks. Molt number and mortality were monitored throughout the course of the experiment. After the 8 week exposure, amphipods were analyzed for their biochemical compositions including the Mg/Ca ratio of their exoskeletons. There was no significant difference in biochemical composition or survival among the pH treatments for any of the amphipod species. All three species, however, had significantly fewer total numbers of molts in the pH 7.3 treatment than in the ambient treatment. These results suggest that amphipods may be able to maintain their survival in decreased pH by reallocating energy into compensatory behaviors, such as acid–base regulation, and away from energy expensive processes like molting.
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Antarctic macroalgal-associated amphipod assemblages exhibit long-term resistance to ocean acidificationThe pH of the world’s oceans has decreased since the Industrial Revolution due to the oceanic uptake of increased atmospheric CO2 in a process called ocean acidification. Low pH has been linked to negative impacts on the calcification, growth, and survival of calcifying invertebrates. Along the Western Antarctic Peninsula, dominant brown macroalgae often shelter large numbers of diverse invertebrate mesograzers, many of which are calcified. Mesograzer assemblages in this region are often composed of large numbers of amphipods which have key roles in Antarctic macroalgal communities. Understanding the impacts of acidification on amphipods is vital for understanding how these communities will be impacted by climate change. To assess how long-term acidification may influence the survival of different members in these assemblages, mesograzers, particularly amphipods, associated with the brown alga Desmarestia menziesii were collected from the immediate vicinity of Palmer Station, Antarctica (S64◦460, W64◦030) in January 2020 and maintained under three different pH treatments simulating ambient conditions (approximately pH 8.1), near-future conditions for 2100 (pH 7.7), and distant future conditions (pH 7.3) for 52 days then enumerated. Total assemblage number and the relative proportion of each species in the assemblage were found to be similar across the pH treatments. These results suggest that amphipod assemblages associated with D. menziesii may be resistant to long-term exposure to decreased pH.
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Seasonality and hydroclimatic variability shape the functional and taxonomic diversity of nearshore fish communities in glacierized estuaries of AlaskaNearshore fish communities in glacierized estuaries contend with environmental changes brought on by seasons and a shifting climate, which include alterations in freshwater runoff and environmental conditions shaped by the interplay of warming temperatures and receding glaciers. Spatial and temporal changes in environmental parameters can directly impact fish behavior and community structure, thereby affecting the dynamics of the entire ecosystem. Taxonomic diversity is commonly used to measure changes in communities, and while it offers important insights into community structure, considering the functional roles of organisms is necessary for understanding community dynamics through expressed traits and trophic interactions. Here, we evaluate the influence of environmental drivers on both taxonomic and functional diversity of fish communities at multiple sites in two glacially-influenced, high-latitude regions in the Gulf of Alaska (GoA): oceanic-influenced Kachemak Bay and the more typical estuarine Lynn Canal. Sites were analyzed monthly (April–September) for three years (2019, 2021, 2022) to address two questions: (1) Do taxonomic and functional diversity of nearshore fish communities show similar patterns of interannual and regional variation in glacially-influenced GoA estuaries? and (2) Do similar seasonal (i.e., monthly) and environmental (i.e., temperature, salinity, turbidity, freshwater discharge) drivers shape taxonomic and functional fish communities within these regions? Taxonomic and functional diversity were both significantly different between the two glacially-influenced GoA regions in all years. Environmental drivers of these patterns differed, but were weak across regional comparisons. Regional taxonomic composition was correlated to temperature, salinity, and turbidity while regional functional composition was not related to any environmental variables. Within regions, seasonality played a much stronger role in structuring Lynn Canal taxonomic and functional composition compared to Kachemak Bay where a stronger interannual signature was present. Taxonomic composition in Kachemak Bay was correlated with similar environmental variables to the regional comparison while Lynn Canal taxonomic composition was correlated to salinity and discharge. Both regions exhibited weak or non-existent relationships of functional composition to environmental drivers. In the more freshwater-influenced Lynn Canal, strong taxonomic and functional coupling across months indicates that seasonality structures communities, while in the more oceanic Kachemak Bay, weak seasonal differences and strong interannual differences indicate a system more influenced by oceanographic processes, as opposed to local changes.
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Glacier runoff impacts the stoichiometry of riverine nutrient export from coastal Alaskan catchmentsUnderstanding the impacts of glacier change on riverine ecosystems is limited by a lack of multi-year studies in glacierized mountain catchments quantifying the magnitude and stoichiometry of riverine biogeochemical yields. Here we evaluate riverine concentration-discharge relationships using the power function between daily runoff and element yields and stoichiometry across 10 catchments of varying glacial coverage within two climatically distinct regions in the Gulf of Alaska. Our multi-year study showed that biogeochemical stoichiometry and concentration-discharge relationships for dissolved carbon, nitrogen, and phosphorus varied significantly with catchment glacier coverage across both regions. This stoichiometric variability could drive regional differences in proglacial riverine food webs given that high trophic levels in low productivity rivers are generally driven by bottom-up controls. The coherence of our findings across the Gulf of Alaska suggests that observed patterns in concentration-discharge relationships are likely globally generalizable to catchments in which discharge is dominated by glacier ice and/or snowmelt.
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Using eDNA to supplement population genetic analyses for cryptic marine species: Identifying population boundaries for Alaska harbour porpoisesIsolation by distance and biogeographical boundaries define patterns of population genetic structure for harbour porpoise along the Pacific coast from California to British Columbia. Until recently, inadequate sample sizes in many regions constrained efforts to characterise population genetic structure throughout the coastal waters of Alaska. Here, tissue samples from beachcast strandings and fisheries bycatch were supplemented with targeted environmental DNA (eDNA) samples in key regions of Alaska coastal and inland waters. Using a geographically explicit, hierarchical approach, we examined the genetic structure of Alaska harbour porpoises, using both mitochondrial DNA (mtDNA) sequence data and multilocus SNP genotypes. Despite a lack of evidence of genetic differentiation from nuclear SNP loci, patterns of relatedness and genetic differentiation from mtDNA suggest natal philopatry at multiple geographic scales, with limited gene flow among sites possibly mediated by male dispersal. A priori clustering of sampled areas at an intermediate scale (eastern and western Bering Sea, Gulf of Alaska and Southeast Alaska) best explained the genetic variance (12.37%) among regions. In addition, mtDNA differentiation between the Gulf of Alaska and eastern Bering Sea, and among regions within the Gulf of Alaska, indicated significant genetic structuring of harbour porpoise populations in Southeast Alaska. The targeted collection of eDNA samples from strata within Southeast Alaska was key for elevating the statistical power of our mtDNA dataset, and findings indicate limited dispersal between neighbouring strata within coastal and inland waters. These results provide evidence supporting a population boundary within the currently recognised Southeast Alaska Stock. Together, these findings will prove useful for ongoing management efforts to reduce fisheries conflict and conserve genetic diversity in this iconic coastal species.
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Development of scalable coastal and offshore kelp farming for marine biomass productionThe US DOE/ARPA-E MARINER program funded a 4-year project to determine an optimal way to grow kelps in large, nearshore and offshore arrays for the eventual purpose of biofuel production with the goal of keeping the cost below $80 USD per dry metric ton of kelp. This project specifically looked at how Saccharina latissima can be grown in the Gulf of Alaska to reach that goal. There were three major aspects of the research: (1) optimize nursery production and seeding lines for outplanting; (2) design an economical, modular outplanting structure; and (3) develop methods to efficiently harvest the product. Farm designs were based on catenary structures and the use of spreader bars with variable spacing of grow-lines and line types. The spacing of the grow-lines makes a difference in the yield. Grow-line spacing of ≥1.5 m showed about a 50% increase in production (kg m−1). There was no statistical difference in the growth of Saccharina latissima whether in the middle or the outside of the array, but the line type and perhaps line thickness can make a difference in yield. Sagging caused by the weight of the mature fronds resulted in lower growth at depth. Various harvesting approaches for mature kelps were tested by collaborating farmers. One promising innovation is the use of large bags with mesh for temporarily holding the freshly harvested fronds in seawater. Although the weight of the fronds on the grow-lines causes the lines to sink, the bags packed with the harvested fronds float, allowing for temporary storage before loading to a vessel heading to port and processing. Another advance in harvesting is a specially built harvest vessel, the Harvest Buddy, allowing a more mechanized and faster way to harvest. A techno-economic assessment (TEA) using our data has pointed to solutions to reach the goal of $80 USD per dry metric ton of kelp.
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Impacts of ocean acidification on the palatability of two Antarctic macroalgae and the consumption of a grazerIncreases in atmospheric CO2 have led to more CO2 entering the world’s oceans, decreasing the pH in a process called ’ocean acidification’. Low pH has been linked to impacts on macroalgal growth and stress, which can alter palatability to herbivores. Two common and ecologically important macroalgal species from the western Antarctic Peninsula, the unpalatable Desmarestia menziesii and the palatable Palmaria decipiens, were maintained under three pH treatments: ambient (pH 8.1), near future (7.7) and distant future (7.3) for 52 days and 18 days, respectively. Discs of P. decipiens or artificial foods containing extracts of D. menziesii from each treatment were presented to the amphipod Gondogeneia antarctica in feeding choice experiments. Additionally, G. antarctica exposed to the different treatments for 55 days were used in a feeding assay with untreated P. decipiens. For D. menziesii, extracts from the ambient treatment were eaten significantly more by weight than the other treatments. Similarly, P. decipiens discs from the ambient and pH 7.7 treatments were eaten more than those from the pH 7.3 treatment. There was no significant difference in the consumption by treated G. antarctica. These results suggest that ocean acidification may decrease the palatability of these macroalgae to consumers but not alter consumption by G. antarctica.
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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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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.
