A preliminary investigation of the lichen biota associated with recently deglaciated terrain in southeastern Alaska

Glaciers worldwide are currently retreating at unprecedented rates, revealing large tracts of newly exposed rock and till. We present the results of a preliminary, qualitative investigation of the lichen diversity of transient habitats near three glaciers in southeastern Alaska: Muir Glacier within Glacier Bay National Park, and Baird and Patterson Glaciers in the Tongass National Forest. This work is noteworthy as it (i) documents previously undescribed lichen species and communities within rapidly changing glacier habitats, (ii) illustrates the importance of cryptogams (lichens, bryophytes, algae, and cyanobacteria) in the primary colonization of recently deglaciated terrain, (iii) sets apart the lichen biota of recently deglaciated terrain in southeastern Alaska from that of other glacial regions worldwide (e.g., the European Alps, Svalbard, and southern South America) and even other parts of Alaska (e.g., Brooks Range), and (iv) emphasizes the importance of more lichen studies that focus on this rapidly changing habitat. The lichen biotas found at different successional stages near these glaciers are described and compared. The role of lichens and other cryptogams in post-glacial vegetation initiation, the threats to the lichen biota, and suggestions for the possible origins of the lichen propagules that colonize these newly exposed surfaces are also discussed.

Underwater Sound Levels in Glacier Bay During Reduced Vessel Traffic Due to the COVID-19 Pandemic

The global COVID-19 pandemic caused a sharp decline in vessel traffic in many areas around the world, including vessel-based tourism throughout Alaska, USA in 2020. Marine vessel traffic has long been known to affect the underwater acoustic environment with direct and indirect effects on marine ecological processes. Glacier Bay National Park in southeastern Alaska has monitored underwater sound since 2000. We used continuous, calibrated hydrophone recordings to examine 2020 ambient sound levels compared with previous years: 2018, the most recent year with data available, and 2016 for historical perspective. Park tourism occurs mainly in May–September. Overall, the number of vessel entries in Glacier Bay was 44–49% lower in 2020 (2020: n = 1,831; 2018: n = 3,599; 2016: n = 3,212) affecting all vessel classes, including the complete absence of cruise ships and only three tour vessel trips. In all years, we found clear seasonal and diurnal patterns in vessel generated noise, focused from 06:00 to 20:00 local time (LT) in the summer months. Broadband (17.8–8,910 Hz) sound levels in the 2020 Visitor Season were 2.7 dB lower than 2018 and 2.5 dB lower than 2016. Focusing on morning (06:00–09:00 LT) and afternoon (15:00–18:00 LT) time-blocks when tour vessels and cruise ships enter and exit Glacier Bay, median broadband sound levels were 3.3–5.1 dB lower in 2020 than prior years. At the 95th percentile levels, morning and afternoon peak times in 2020 were 6.3–9.0 dB quieter than previous years. A 3 dB decline in median sound level in the 125 Hz one-third octave band in 2020 reflects a change in medium and large vessel noise energy and/or harbor seal vocalizations. Our results suggest that all types of vessels had a role in the quieter underwater sound environment in 2020, with the combined acoustic footprint of tour vessels and cruise ships most evident in the decrease in the 95th percentile loudest sounds. This and other descriptions of the pandemic-induced quiet, and the gradual return to increased activity, can help inform efforts to improve existing methods to mitigate vessel noise impacts and maintain the ecological integrity of marine protected areas.

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.

Emplacement dynamics of supraglacial rock avalanches: details from the 2016 Lamplugh event, Alaska

<p>In Glacier Bay Park and Preserve, Alaska, at least 25 rock avalanches occurred since the mid-1980s. The 2016 Lamplugh rock avalanche, with roughly 70 Mm<sup>3 </sup>deposit volume, is one of the larger events within the park. It originated from a north-facing bedrock ridge without any obvious trigger, and spread 10 km down Lamplugh Glacier. Based on field surveys, high-resolution digital elevation models, and continuous seismic data, we show that the emplacement dynamics of this supraglacial rock avalanche can be described by two distinct stages. Clear long-period seismic signals during Stage-1 record strong interactions of the rock avalanche debris with the ground, suggesting dynamic processes such as grain collisions and fragmentation ('active or dynamic emplacement' of a granular flow). During this first stage, the debris traveled about 5 km from the base of the slope; its deposit is thin and stretched with a dominant dry and flat area in the center, and has narrow raised margins. Stage-2 was essentially aseismic at long periods and dominated by low-friction sliding at slow deceleration rates ('passive sliding'). This sliding produced the distal roughly third of the total runout length where the deposit has a higher density of flowbands and more prominent, raised margins from entrainment and bulldozing of snow. The higher apparent mobility of supraglacial landslides (relative to their counterparts in other runout environments) may be explained by this two-stage model.</p>

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.