Glacier Bay National Research Articles

A 36-Year Record of Rock Avalanches in the Saint Elias Mountains of Alaska, With Implications for Future Hazards

Glacial retreat and mountain-permafrost degradation resulting from rising global temperatures have the potential to impact the frequency and magnitude of landslides in glaciated environments. Several recent events, including the 2015 Taan Fiord rock avalanche, which triggered a tsunami with one of the highest wave runups ever recorded, have called attention to the hazards posed by landslides in regions like southern Alaska. In the Saint Elias Mountains, the presence of weak sedimentary and metamorphic rocks and active uplift resulting from the collision of the Yakutat and North American tectonic plates create landslide-prone conditions. To differentiate between the typical frequency of landsliding resulting from the geologic and tectonic setting of this region, and landslide processes that may be accelerated due to changes in climate, we used Landsat imagery to create an inventory of rock avalanches in a 3700 km2 area of the Saint Elias Mountains. During the period from 1984-2019, we identified 220 rock avalanches with a mean recurrence interval of 60 days. We compared our landslide inventory with a catalog of M ≥ 4 earthquakes to identify potential coseismic events, but only found three possible earthquake-triggered rock avalanches. We observed a distinct temporal cluster of 41 rock avalanches from 2013 through 2016 that correlated with above average air temperatures (including the three warmest years on record in Alaska, 2014-2016); this cluster was similar to a temporal cluster of recent rock avalanches in nearby Glacier Bay National Park and Preserve. The majority of rock avalanches initiated from bedrock ridges in probable permafrost zones, suggesting that ice loss due to permafrost degradation, as opposed to glacial thinning, could be a dominant factor contributing to rock-slope failures in the high elevation areas of the Saint Elias Mountains. Although earthquake-triggered landslides have episodically occurred in southern Alaska, evidence from our study suggests that area-normalized rates of non-coseismic rock avalanches were greater during the period from 1964 to 2019, and that the frequency of these events will continue to increase as the climate continues to warm. These findings highlight the need for hazard assessments in Alaska that address changes in landslide patterns related to climate change.

Calibrating and Adjusting Counts of Harbor Seals in a Tidewater Glacier Fjord to Estimate Abundance and Trends 1992 to 2017

Long-term monitoring for understanding status and trend of species of conservation concern is undeniably valuable, yet monitoring methods often evolve over time. From 1992 to 2017, two different monitoring methods were used to assess abundance and trends of seals in Glacier Bay National Park, Alaska: shore-based counts by observers (1992–2002) and aerial photographic surveys (2007–2017). In a recently published paper, we developed an analytical calibration between the two methods that improves continuity for long-term monitoring for a species of conservation concern by taking advantage of new sampling methods and innovations in analytical approaches. These photographs illustrate the article “Calibrating and Adjusting Counts of Harbor Seals in a Tidewater Glacier Fjord to Estimate Abundance and Trends 1992–2017” by Jamie N. Womble, Jay M. Ver Hoef, Scott M. Gende, Elizabeth A. Mathews published in Ecosphere. https://doi.org/10.1002/ecs2.3111

Using a Bayesian Multistate Occupancy Model to Assess Seabird and Shorebird Status in Glacier Bay, Alaska

ABSTRACTThe U.S. Department of Interior National Park Service is charged with both monitoring avian communities and evaluating the influence of visitors to National Parks on sensitive species; however, this task is challenging considering that sampling programs often involve multiple species, each with differing behavior, habitat requirements, and detectability. Our objectives were to build a model to describe the status of waterbirds in Glacier Bay National Park, Alaska, USA, and assess effects of area closures on these species. We used a Bayesian multistate occupancy model to describe the status of multiple species and make the best possible use of existing survey data. We modeled up to 5 states per species and evaluated predictors of occupancy, nesting, and abundance, as well as survey‐related predictors of state‐dependent detection probability. We found that occupancy probability varied across species and habitats (islands vs. glacial outwashes). For most species, occupancy probability was substantially greater at sites occupied in the year previous (site persistence). We found weak evidence that area closures affected the occurrence of species in the study, but this was largely because most sites were closed for the entirety of the study period. The probability of detecting occurrence, nesting, and abundance varied across species and survey methods (ground vs. vessel). Detection parameters provided valuable information for enhancing the efficiency of future surveys, by identifying preferred survey methods and sampling periods for specific waterbird species. © 2020 The Wildlife Society.

Potential utility of geomagnetic data for geolocation of demersal fishes in the North Pacific Ocean

BackgroundArchival tags that measure the Earth’s magnetic field could provide a new geolocation method for demersal fishes in the North Pacific Ocean. However, the presence of local magnetic field anomalies caused by geological formations such as volcanic rock and temporal fluctuations from solar storms could complicate its use in some high-latitude areas of the North Pacific Ocean. We assessed the potential value of adding geomagnetic data to a depth-based state-space model for geolocation of demersal fishes in Glacier Bay National Park, USA, a high-latitude magnetic anomaly area. We developed a high-resolution (100 m) magnetic field map of the study area and assessed in situ tag resolution by deploying 5 geomagnetic archival tags on a stationary mooring for 8 months. We compared performance of 4 theoretical geomagnetic tag measurement resolutions (low = ± 1000 nT, medium = ± 500 nT, high = ± 300 nT, and very high = ± 150 nT), 2 map resolutions (coarse- or fine-scale), and 5 methods of geomagnetic variance specification by estimating locations of simulated random walk trajectories under the different treatment scenarios using a hidden Markov model.ResultsGeomagnetic data improved model performance for both fine-scale and coarse-scale magnetic maps when tag resolutions were medium to very high and geomagnetic variance specification was based on error between measured and mapped values instead of study area attributes such as slope or roughness. Overall, the best model performance was observed for the highest tag resolution, the fine-scale map, and variance based on anomaly magnitudes. However, the coarse-scale map with a constant variance of 165 nT resulted in improvements over depth alone for all tag resolutions. In situ testing of mooring data suggests that the precision of the geomagnetic archival tags was comparable to the low and medium tag measurement resolutions tested in simulations, but variation in performance was high among tags.ConclusionsOur results suggest that inclusion of geomagnetic data could improve geolocation of demersal fishes in the North Pacific Ocean, but improvements to geomagnetic tags and additional information on magnetic field values measured at the seafloor compared to the sea surface are needed to ensure its utility.

Human-caused climate change in United States national parks and solutions for the future

Author(s): Gonzalez, Patrick | Abstract: Human-caused climate change has exposed the US national park area to more severe increases in heat and aridity than the country as a whole and caused widespread impacts on ecosystems and resources. Reducing carbon dioxide emissions from cars, power plants, and other human sources would reduce future risks. Since 1895, annual average temperature of the area of the 419 national parks has increased at a rate of 1.0 ± 0.2oC (1.8 ± 0.4oF) per century, double the rate of the US as a whole, while precipitation has declined significantly on 12% of national park area, compared with 3% of the US. This occurs because extensive areas of national parks are located in extreme environments. Scientific research in national parks has detected numerous changes that analyses have attributed primarily to human-caused climate change. These include a doubling of the area burned by wildfire across the western US, including Yosemite National Park, melting of glaciers in Glacier Bay National Park, a doubling of tree mortality across the western US, including Sequoia National Park, a loss of bird species from Death Valley National Park, a shift of trees onto tundra in Noatak National Preserve, sea level rise of 42 cm (17 in.) near the Statue of Liberty National Monument, and other impacts. Without emissions reductions, climate change could increase temperatures across the national parks, up to 9oC (16oF) by 2100 in parks in Alaska. This could melt all glaciers from Glacier National Park, raise sea level enough to inundate half of Everglades National Park, dissolve coral reefs in Virgin Islands National Park through ocean acidification, and damage many other natural and cultural resources. Adaptation measures, including conservation of refugia in Joshua Tree National Park and raising heat-resistant local corals in Biscayne National Park, can strengthen ecosystem integrity. Yet, reducing greenhouse gas emissions from human activities is the only solution that prevents the pollution that causes climate change. Energy conservation and efficiency improvements, renewable energy, public transit, and other actions could lower projected heating by two-thirds, reducing risks to our national parks.

Acoustically advertising male harbour seals in southeast Alaska do not make biologically relevant acoustic adjustments in the presence of vessel noise.

Aquatically breeding harbour seal (Phoca vitulina) males use underwater vocalizations during the breeding season to establish underwater territories, defend territories against intruder males, and possibly to attract females. Vessel noise overlaps in frequency with these vocalizations and could negatively impact breeding success by limiting communication space. In this study, we investigated whether harbour seals employed anti-masking strategies to maintain communication in the presence of vessel noise in Glacier Bay National Park and Preserve, Alaska. Harbour seals in this location did not sufficiently adjust source levels or acoustic parameters of vocalizations to compensate for acoustic masking. Instead, for every 1 dB increase in ambient noise, signal excess decreased by 0.84 dB, indicating a reduction in communication space when vessels passed. We suggest that harbour seals may already be acoustically advertising at or near a biologically maximal sound level and therefore lack the ability to increase call amplitude to adjust to changes in their acoustic environment. This may have significant implications for this aquatically breeding pinniped, particularly for populations in high noise regions.

Calibrating and adjusting counts of harbor seals in a tidewater glacier fjord to estimate abundance and trends 1992 to 2017

AbstractLong‐term monitoring for understanding status and trend of species of conservation concern is undeniably valuable, yet monitoring methods often evolve over time due to the development of new technology, fluctuations in funding, logistical constraints, and innovations in sampling methods or analytical approaches. Consequently, valuable insights into annual or decadal‐scale trends can be lost unless calibration between historical and current methods is developed. Glacier Bay National Park, in southeastern Alaska, hosts an important regional population of harbor seals, with the majority of seals pupping and molting on icebergs calved from a tidewater glacier in Johns Hopkins Inlet. Monitoring efforts to assess abundance and trends of harbor seals used counts of seals by shore‐based observers from 1992 to 2002, but transitioned to aerial photographic surveys in 2007 through 2017. To produce a rigorous long‐term evaluation of abundance and trends of harbor seals, we (1) conducted concurrent shore‐based counts and aerial photographic surveys in 2007 and 2008; (2) developed an analytical calibration between the two monitoring methods; (3) developed a haul‐out model to estimate the number of harbor seals in the water at the time of counts; and (4) estimated abundance and trends of harbor seals from 1992 to 2017 from the adjusted counts. Our calibration analysis revealed that during the pupping season in June, counts of harbor seals by observers from shore were consistently lower than counts from aerial surveys. During the molting season, counts by shore‐based observers were only slightly less than aerial photographic surveys, and there was an interaction between survey method and season. After calibrating methods, we found important decadal‐scale changes in trend. Over the 26‐yr period (1992–2017), the estimated trend was negative; however, trends computed for rolling 10‐yr time intervals showed steep and significant declines ending around 2011, with leveling off and possibly some subsequent recovery. The most recent shorter‐term (2013–2017) trends are negative again, rivaling the steepest decreases over the 26‐yr period. Our calibration between two monitoring methods improved continuity for long‐term monitoring for a species of conservation concern by taking advantage of new sampling methods and innovations in analytical approaches.

Lichens and associated fungi from Glacier Bay National Park, Alaska.

Lichens are widely acknowledged to be a key component of high latitude ecosystems. However, the time investment needed for full inventories and the lack of taxonomic identification resources for crustose lichen and lichenicolous fungal diversity have hampered efforts to fully gauge the depth of species richness in these ecosystems. Using a combination of classical field inventory and extensive deployment of chemical and molecular analysis, we assessed the diversity of lichens and associated fungi in Glacier Bay National Park, Alaska (USA), a mixed landscape of coastal boreal rainforest and early successional low elevation habitats deglaciated after the Little Ice Age. We collected nearly 5000 specimens and found a total of 947 taxa, including 831 taxa of lichen-forming and 96 taxa of lichenicolous fungi together with 20 taxa of saprotrophic fungi typically included in lichen studies. A total of 98 species (10.3% of those detected) could not be assigned to known species and of those, two genera and 27 species are described here as new to science: Atrophysma cyanomelanos gen. et sp. nov., Bacidina circumpulla, Biatora marmorea, Carneothele sphagnicola gen. et sp. nov., Cirrenalia lichenicola, Corticifraga nephromatis, Fuscidea muskeg, Fuscopannaria dillmaniae, Halecania athallina, Hydropunctaria alaskana, Lambiella aliphatica, Lecania hydrophobica, Lecanora viridipruinosa, Lecidea griseomarginata, L. streveleri, Miriquidica gyrizans, Niesslia peltigerae, Ochrolechia cooperi, Placynthium glaciale, Porpidia seakensis, Rhizocarpon haidense, Sagiolechia phaeospora, Sclerococcum fissurinae, Spilonema maritimum, Thelocarpon immersum, Toensbergia blastidiata and Xenonectriella nephromatis. An additional 71 'known unknown' species are cursorily described. Four new combinations are made: Lepra subvelata (G. K. Merr.) T. Sprib., Ochrolechia minuta (Degel.) T. Sprib., Steineropsis laceratula (Hue) T. Sprib. & Ekman and Toensbergia geminipara (Th. Fr.) T. Sprib. & Resl. Thirty-eight taxa are new to North America and 93 additional taxa new to Alaska. We use four to eight DNA loci to validate the placement of ten of the new species in the orders Baeomycetales, Ostropales, Lecanorales, Peltigerales, Pertusariales and the broader class Lecanoromycetes with maximum likelihood analyses. We present a total of 280 new fungal DNA sequences. The lichen inventory from Glacier Bay National Park represents the second largest number of lichens and associated fungi documented from an area of comparable size and the largest to date in North America. Coming from almost 60°N, these results again underline the potential for high lichen diversity in high latitude ecosystems.

Phenotypic Plasticity or a Reproductive Dead End? Primnoa pacifica (Cnidaria: Alcyonacea) in the Southeastern Alaska Region

Red tree corals (Primnoa pacifica) are abundant in the eastern Gulf of Alaska, from the glacial fjords of Southeast Alaska where they emerge to as shallow as 6 m, to the continental shelf edge and seamounts where they are more commonly found at depths greater than 150 m. This keystone species forms large thickets, creating habitat for many associated species, including economically valuable fishes and crabs, and so are important benthic suspension feeders in this region. Though the reproductive periodicity over 1.5 year period was reported in 2014 from a shallow fjord (Tracy Arm), this study examined reproductive ecologies from 8 sites – two within Glacier Bay National Park and Preserve, three on the continental shelf edge, one within Endicott Arm (Holkham Bay) and two time points from the Tracy Arm (Holkham Bay) study. Male reproductive traits were similar at all sites but there were distinct differences in oogenesis. Though fecundity mostly showed no significant difference between sites, there was a trend of increasing number of eggs with depth. Indeed, the average oocyte sizes from Tracy Arm (the shallowest site) was 105 m, whereas from Shutter Ridge (one of the deepest sites) the average size was 309 m. Moreover, the maximum oocyte size at Tracy Arm was 802 m, whereas it was 2120 m at Dixon Entrance, an almost 3-fold difference, and one not usually observed within a single species. We propose two theories to explain the observed differences, a) this species shows great phenotypic plasticity in reproductive ecology, adjusting to different environmental variables based on energetic need and potentially demonstrating micro-evolution; or b) the fjord sites are at a reproductive dead end, with the stress of shallow water conditions effectively preventing gametogenesis reaching full potential and likely limiting successful reproductive events from occurring, at least on a regular basis.

100yr of primary succession highlights stochasticity and competition driving community establishment and stability.

The study of community succession is one of the oldest pursuits in ecology. Challenges remain in terms of evaluating the predictability of succession and the reliability of the chronosequence methods typically used to study community development. The research of William S. Cooper in Glacier Bay National Park is an early and well-known example of successional ecology that provides a long-term observational data set to test hypotheses derived from space-for-time substitutions. It also provides a unique opportunity to explore the importance of historical contingencies and as an example of a revitalized historical study system. We test the textbook successional trajectory in Glacier Bay and evaluate long-term plant community development via primary succession through extensive fieldwork, remote sensing, dendrochronological methods, and newly discovered data that fills in data gaps (1940s to late 1980s) in continuous measurement over 100+ years. To date, Cooper's quadrats do not support the classic facilitation model of succession in which a sequence of species interacts to form predictable successional trajectories. Rather, stochastic early community assembly and subsequent inhibition have dominated; most species arrived shortly after deglaciation and have remained stable for 50+ years. Chronosequence studies assuming prior composition are thus questionable, as no predictable species sequence or timeline was observed. This underscores the significance of assumptions about early conditions in chronosequences and the need to defend such assumptions. Furthermore, this work brings a classic study system in ecology up to date via a plot size expansion, new baseline biogeochemical data, and spatial mapping for future researchers for its second century of observation.

A Song Remembered in Place: Tlingit Composer Mary Sheakley (Loo) and Huna Tlingits in Glacier Bay National Park, Alaska

Songs among the Tlingit of Alaska and Canada are important means for communicating and aligning relationships, knowledges, and emotions among humans, non-human persons, and ancestral lands. As potent expressions of individual and collective identity, heritage, and destiny, songs encapsulate ethnobiological, social, and geographic knowledges in a melodious, interspecific lingua franca. A particular ancestral or communal context, such as a potlatch or u.eex', may call for a spiritual, mournful, or happy song to help effect a transition, for example from mourning to celebration or death to rebirth. Ceremonial songs are typically owned as property and performed by particular Tlingit matrilineal groups, known as clans, or their house groups. However, songs are in the first instance composed by individuals, typically in response to other unique events, such as extraordinary encounters with wildlife, disasters, or other remarkable circumstances. The composers of such songs, both men and women, are respected and honored for their skills. Mary Sheakley (Loo) is one such figure. She composed the song presented here in response to a group of wolves that came to the beach and howled as she and her fellow paddler left their subsistence camp in what is now Glacier Bay National Park and Preserve around the turn of the twentieth century. In 1996, the song was spontaneously remembered by a contemporary elder and younger clan sister to Mary Sheakley, Amy Marvin, who, in turn, taught it to her younger clan daughter during a berry picking trip to Glacier Bay. Later, during that same trip, Amy Marvin deployed the song to cap an impromptu ritual of commemoration for Tlingit relatives that died in a tragic boating accident in the Park in the late twentieth century. The song was thus not only revived but elevated in status to become a “clan song,” which is now considered sacred property (at.oow) and performed during ceremonies, such as the potlatch or u.eex'.

Comparing the Underwater Soundscapes of Four U.S. National Parks and Marine Sanctuaries

Passive acoustic sensors provide a cost-effective tool for monitoring marine environments. Documenting acoustic conditions among habitats can provide insights into temporal changes in ecosystem composition and anthropogenic impacts. Agencies tasked with safeguarding marine protected areas, such as the U.S. National Park Service and U.S. National Oceanic and Atmospheric Administration’s Office of National Marine Sanctuaries, are increasingly interested in using long-term monitoring of underwater sounds as a means of tracking species diversity and ecosystem health. In this study, low-frequency passive acoustic recordings were collected fall 2014 - spring 2018, using standardized instrumentation, from four marine protected areas across geographically disparate regions of the U.S. Economic Exclusive Zone: Northwest Atlantic, Northeast Pacific, South Pacific, and Caribbean. Recordings were analyzed for differences in seasonal conditions and to identify acoustic metrics useful for resource assessment across all sites. In addition to comparing ambient sound levels, a species common to all four sites, the humpback whale (Megaptera novaeangliae), was used to compare biological sound detection. Ambient sound levels varied across the sites and were driven by differences in animal vocalization rates, anthropogenic activity, and weather. The highest sound levels (dBRMS (50 Hz-1.5 kHz) re 1 μPa) were recorded in the Northwest Atlantic in Stellwagen Bank National Marine Sanctuary (Stellwagen) during the boreal winter-spring resulting from bioacoustic activity, vessel traffic, and high wind speeds. The lowest sound levels (dBRMS (50 Hz-1.5 kHz) re 1 μPa) were recorded in the Northeast Pacific adjacent to a vessel-restricted area of Glacier Bay National Park and Preserve (Glacier Bay) during the boreal summer. Humpback whales were detected seasonally in the southern latitude sites, and throughout the deployment periods in the northern latitude sites. Temporal trends in band and spectrum sound levels in Glacier Bay and the National Park of American Samoa were primarily driven by biological sound sources, while trends in Stellwagen and the Buck Island Reef National Monument were primarily driven by anthropogenic sources. These results highlight the variability of ambient sound conditions in marine protected areas in U.S. waters, and the utility of long-term soundscape monitoring for condition assessment in support of resource management.

Seasonal components of freshwater runoff in Glacier Bay, Alaska: diverse spatial patterns and temporal change

Abstract. A high spatial resolution (250 m), distributed snow evolution and ablation model, SnowModel, is used to estimate current and future scenario freshwater runoff into Glacier Bay, Alaska, a fjord estuary that makes up part of Glacier Bay National Park and Preserve. The watersheds of Glacier Bay contain significant glacier cover (tidewater and land-terminating) and strong spatial gradients in topography, land cover, and precipitation. The physical complexity and variability of the region produce a variety of hydrological regimes, including rainfall-, snowmelt-, and ice-melt-dominated responses. The purpose of this study is to characterize the recent historical components of freshwater runoff to Glacier Bay and quantify the potential hydrological changes that accompany the worst-case climate scenario during the final decades of the 21st century. The historical (1979–2015) mean annual runoff into Glacier Bay is found to be 24.5 km3 yr−1, or equivalent to a specific runoff of 3.1 m yr−1, with a peak in July, due to the overall dominance of snowmelt processes that are largely supplemented by ice melt. Future scenarios (2070–2099) of climate and glacier cover are used to estimate changes in the hydrologic response of Glacier Bay. Under the representative concentration pathway (RCP) 8.5, the mean of five climate models produces a mean annual runoff of 27.5 km3 yr−1, 3.5 m yr−1, representing a 13 % increase from historical conditions. When spatially aggregated over the entire bay region, the projection scenario seasonal hydrograph is flatter, with weaker summer flows and higher winter flows. The peak flows shift to late summer and early fall, and rain runoff becomes the dominant overall process. The timing and magnitudes of modeled historical runoff are supported by a freshwater content analysis from a 24-year oceanographic conductivity–temperature–depth (CTD) dataset from the U.S. National Park Service's Southeast Alaska Inventory and Monitoring Network (SEAN). The hydrographs of individual watersheds display a diversity of changes between the historical period and projection scenario simulations, depending upon total glacier coverage, elevation distribution, landscape characteristics, and seasonal changes to the freezing line altitude.

Underwater Acoustic Ecology Metrics in an Alaska Marine Protected Area Reveal Marine Mammal Communication Masking and Management Alternatives

Vessel-generated underwater noise can affect humpback whales, harbor seals and other marine mammals by decreasing the distance over which they can communicate and detect predators and prey. Emerging analytical methods allow marine protected area managers to use biologically relevant metrics to assess vessel noise in the dominant frequency bands used by each species. Glacier Bay National Park (GBNP) in Alaska controls summer visitation with daily quotas for vessels ranging from cruise ships to yachts and skiffs. Using empirical data (weather, AIS vessel tracks, marine mammal survey data and published behavioral parameters) we simulated the movements and acoustic environment of whales and seals on three days with differing amounts of vessel traffic and natural ambient noise. We modeled communication space (CS) to compare the area over which a vocalizing humpback whale or harbor seal could communicate with conspecifics in the current ambient noise environment (at 10-min intervals) relative to how far it could communicate under naturally quiet conditions, known as the reference ambient noise condition (RA). RA was approximated from the quietest 5th percentile noise statistics based on a year (2011) of continuous audio data from a hydrophone in GBNP, in the frequency bands of whale and seal sounds of interest: humpback “whup” calls (50-700 Hz, 143 dB re 1 µPa source level, SL); humpback song (224-708 Hz, 175 dB SL), and harbor seal roars (40-500 Hz, 144 dB SL). Results indicate that typical summer vessel traffic in GBNP causes substantial CS losses to singing whales (reduced by 13-28%), calling whales (18-51%) and roaring seals (32-61%), especially during daylight hours and even in the absence of cruise ships. Synchronizing the arrival and departure timing of cruise ships did not affect CS for singing whales, but restored 5 – 12% of lost CS for roaring seals and calling whales, respectively. Metrics and visualizations like these create a common currency to describe and explore methods to assess and mitigate anthropogenic noise. Important next steps toward facilitating effective conservation of the underwater sound environments will involve putting modeling tools in the hands of marine protected area managers for ongoing use.

Somewhere between acceptable and sustainable: When do impacts to resources become too large in protected areas?

Utilization of marine and terrestrial protected areas is fundamentally important for their acceptance and success. Yet even appropriate uses can negatively impact resources requiring managers to make decisions as to when the impacts become unacceptably large. These decisions can be difficult because the level at which impacts occur may be far below the level at which resource persistence is threatened. In Glacier Bay National Park, Alaska, managers must make a recurring decision regarding the number of cruise ships that are allowed to enter the park each year. Cruise ships bring >95% of all visitors to the park but have been involved in several lethal collisions (ship strikes) with humpback whales. Using an individual-based simulation model, we demonstrate that increasing the annual ship volume from current to maximum allowable levels would have negligible impacts on population growth of whales. Over the next 30 years the median number of collisions would likely increase from 3 (95% CI: 0–7) to 4 (1–8) or, worst case scenario, from 5 (0–7) to 8 (3−13), while median annual growth rates would, at most, shift from 4.4% (3.7%–5.2%) to 4.2% (3.5%–4.9%), depending upon assumptions. By comparison, a median of 67 (50–82) ship strikes would need to occur over the next 30 years to threaten the persistence of whales. Confronted with an impact level that is far below what would threaten the conservation of whales, managers are tasked with the decision of placing values on 2 million additional visitors for every additional dead whale. We argue that decision-making related to use-impact trade-offs for protected areas could be more consistent and effective if site-values are defined explicitly, clearly communicated among stakeholders, and linked to biological metrics. Protected areas managers can then utilize monitoring programs to evaluate management effectiveness when the objective is conserving both resources and values.

Using Stereo Satellite Imagery to Account for Ablation, Entrainment, and Compaction in Volume Calculations for Rock Avalanches on Glaciers: Application to the 2016 Lamplugh Rock Avalanche in Glacier Bay National Park, Alaska

AbstractThe use of preevent and postevent digital elevation models (DEMs) to estimate the volume of rock avalanches on glaciers is complicated by ablation of ice before and after the rock avalanche, scour of material during rock avalanche emplacement, and postevent ablation and compaction of the rock avalanche deposit. We present a model to account for these processes in volume estimates of rock avalanches on glaciers. We applied our model by calculating the volume of the 28 June 2016 Lamplugh rock avalanche in Glacier Bay National Park, Alaska. We derived preevent and postevent 2‐m resolution DEMs from WorldView satellite stereo imagery. Using data from DEM differencing, we reconstructed the rock avalanche and adjacent surfaces at the time of occurrence by accounting for elevation changes due to ablation and scour of the ice surface, and postevent deposit changes. We accounted for uncertainties in our DEMs through precise coregistration and an assessment of relative elevation accuracy in bedrock control areas. The rock avalanche initially displaced 51.7 ± 1.5 Mm3 of intact rock and then scoured and entrained 13.2 ± 2.2 Mm3 of snow and ice during emplacement. We calculated the total deposit volume to be 69.9 ± 7.9 Mm3. Volume estimates that did not account for topographic changes due to ablation, scour, and compaction underestimated the deposit volume by 31.0–46.8 Mm3. Our model provides an improved framework for estimating uncertainties affecting rock avalanche volume measurements in glacial environments. These improvements can contribute to advances in the understanding of rock avalanche hazards and dynamics.

Source levels of foraging humpback whale calls.

Humpback whales produce a wide range of low- to mid-frequency vocalizations throughout their migratory range. Non-song "calls" dominate this species' vocal repertoire while on high-latitude foraging grounds. The source levels of 426 humpback whale calls in four vocal classes were estimated using a four-element planar array deployed in Glacier Bay National Park and Preserve, Southeast Alaska. There was no significant difference in source levels between humpback whale vocal classes. The mean call source level was 137 dBRMS re 1 μPa @ 1 m in the bandwidth of the call (range 113-157 dBRMS re 1 μPa @ 1 m), where bandwidth is defined as the frequency range from the lowest to the highest frequency component of the call. These values represent a robust estimate of humpback whale source levels on foraging grounds and should append earlier estimates.

Predicting the acoustic exposure of humpback whales from cruise and tour vessel noise in Glacier Bay, Alaska, under different management strategies

ESR Endangered Species Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials ESR 34:397-415 (2017) - DOI: https://doi.org/10.3354/esr00857 Theme Section: 21st century paradigms for measuring and managing the effects of anthropogenic ocean noise Predicting the acoustic exposure of humpback whales from cruise and tour vessel noise in Glacier Bay, Alaska, under different management strategies Adam S. Frankel1,2,*, Christine M. Gabriele3 1Marine Acoustics, Incorporated, 4350 N Fairfax Drive, Suite 600, Arlington, VA 22203, USA 2Hawai‘i Marine Mammal Consortium, PO Box 6107, Kamuela, HI 96743, USA 3National Park Service, Glacier Bay National Park & Preserve, PO Box 140, Gustavus, AK 99826, USA *Corresponding author: adam.frankel@marineacoustics.com ABSTRACT: Vessel traffic management regimes intended to protect baleen whales can have unexpected consequences on whale exposure to underwater noise. Using the Acoustic Integration Model, we simulated whale and vessel movements in Glacier Bay National Park (GBNP). We estimated vessel noise exposures to humpback whales Megaptera novaeangliae while varying the number, speed (13 vs. 20 knots [kn]), and timing of cruise ships, and keeping a constant number, speed, and timing of smaller tour vessels. Using calibrated noise signatures for each vessel and the known sound velocity profile and bathymetry of Glacier Bay, we estimated received sound levels for each simulated whale every 15 s in a 24 h period. Simulations with fast ships produced the highest maximal sound pressure level (MSPL) and cumulative sound exposure levels (CSEL). Ships travelling at 13 kn produced CSEL levels 3 times lower than those traveling at 20 kn. We demonstrated that even in cases where a ship is only a few dB quieter at a slower speed, CSEL is lower, but the ship’s transit may take substantially longer. Synchronizing ship arrival times had little effect on CSEL or MSPL but appreciably decreased cumulative sound exposure time (CSET). Overall, our results suggest that the most effective way to reduce humpback whale acoustic exposure in GBNP is to reduce the numbers of cruise ships or their speed, although adjusting ship schedules may also be beneficial. Marine protected area managers may find these results illustrative or adapt these methods to better understand the acoustic effects of specific vessel management circumstances. KEY WORDS: Acoustic propagation · Vessel noise · Chronic exposure · Management · Cumulative effects · Marine Protected Area Full text in pdf format PreviousNextCite this article as: Frankel AS, Gabriele CM (2017) Predicting the acoustic exposure of humpback whales from cruise and tour vessel noise in Glacier Bay, Alaska, under different management strategies. Endang Species Res 34:397-415. https://doi.org/10.3354/esr00857 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in ESR Vol. 34. Online publication date: November 30, 2017 Print ISSN: 1863-5407; Online ISSN: 1613-4796 Copyright © 2017 Inter-Research.

The Role of Season, Tide, and Diel Period in the Presence of Harbor Seal (Phoca vitulina) Breeding Vocalizations in Glacier Bay National Park and Preserve, Alaska

The Role of Season, Tide, and Diel Period in the Presence of Harbor Seal (Phoca vitulina) Breeding Vocalizations in Glacier Bay National Park and Preserve, Alaska

Increasing rock-avalanche size and mobility in Glacier Bay National Park and Preserve, Alaska detected from 1984 to 2016 Landsat imagery

In the USA, climate change is expected to have an adverse impact on slope stability in Alaska. However, to date, there has been limited work done in Alaska to assess if changes in slope stability are occurring. To address this issue, we used 30-m Landsat imagery acquired from 1984 to 2016 to establish an inventory of 24 rock avalanches in a 5000-km2 area of Glacier Bay National Park and Preserve in southeast Alaska. A search of available earthquake catalogs revealed that none of the avalanches were triggered by earthquakes. Analyses of rock-avalanche magnitude, mobility, and frequency reveal a cluster of large (areas ranging from 5.5 to 22.2 km2), highly mobile (height/length < 0.3) rock avalanches that occurred from June 2012 through June 2016 (near the end of the 33-year period of record). These rock avalanches began about 2 years after the long-term trend in mean annual maximum air temperature may have exceeded 0 °C. Possibly more important, most of these rock avalanches occurred during a multiple-year period of record-breaking warm winter and spring air temperatures. These observations suggested to us that rock avalanches in the study area may be becoming larger because of rock-permafrost degradation. However, other factors, such as accumulating elastic strain, glacial thinning, and increased precipitation, may also play an important role in preconditioning slopes for failure during periods of warm temperatures.