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Research about Alaska Peninsula

Source-linked reports with geographic coverage including Alaska Peninsula.

18 recordsLinked to original sources
USGS2022

Inventory of eelgrass (Zostera marina) and seaweeds at the end of the Alaska Peninsula, August–September 2012:

Coastal communities in Alaska are undergoing rapid environmental change from increasing temperatures and baseline data are needed to monitor potential impacts. We conducted the first surveys of the abundance and distribution of eelgrass ( Zostera marina ) and seaweeds in the western part of Izembek National Wildlife Refuge at the end of the Alaska Peninsula. Six embayments and two offshore islands were surveyed in August–September of 2012. Biotic (percent cover of eelgrass/seaweeds, presence/absences of five sessile invertebrates), and abiotic (water temperature, salinity, and depth) data were recorded at 257 survey points (range =9–74 points per site) across all sites. Twenty-two genera/species of seaweeds were identified at the six embayments. New seaweed species for the offshore islands of Sanak and Caton were added to an existing seaweed collection accessioned at the University of British Columbia Herbarium. We also collected samples of eelgrass to be accessioned at U.S. Geological Survey, Alaska Science Center-Molecular Ecology Laboratory, for future genetic analyses. Fifty-three species of birds and 13 species of mammals were observed and recorded during the survey period.

Alaska↗
USGS2018

Inventory of lowland-breeding birds on the Alaska Peninsula

We conducted the first systematic inventory of birds in the lowlands (areas ≤100 m above sea level) of the Alaska Peninsula during summers of 2004–2007 to determine their breeding distributions and habitat associations in this remote region. Using a stratified random survey design, we allocated sample plots by elevation and land cover with a preference for wetland cover types used by shorebirds, a group of particular interest to land managers. We surveyed birds during 10-min counts at 792 points across 52, 5 km × 5 km sample plots distributed from south of the Naknek River (58.70°N,157.00°W) to north of Port Moller (56.00°N,160.52°W). We detected 95 bird species including 19 species of shorebirds and 34 species (36% of total) considered at the time to be of conservation concern for the land managers in the region. The most numerous shorebirds on point counts were dunlin Calidris alpina, short-billed dowitcher Limnodromus griseus, and Wilson's snipe Gallinago delicata. We found the breeding-season endemic marbled godwit Limosa fedoa beringiae at 20 plots within a 3,000-km 2 area from north of Ugashik Bay to just north of Port Heiden and east to the headwaters of the Dog Salmon and Ugashik rivers. The most abundant passerines on point counts were American tree sparrow Spizelloides arborea, Lapland longspur Calcarius lapponicus, and savannah sparrow Passerculus sandwichensis. Sandhill crane Antigone canadensis, glaucous-winged gull Larus glaucescens, and greater scaup Aythya marila were also relatively abundant. We categorized habitat associations for 30 common species and found that lowland herbaceous vegetation supported wetland-focused species including sandhill crane, marbled godwit, short-billed dowitcher, and dunlin; whereas, dwarf shrub-ericaceous vegetation supported tundra-associated species such as willow ptarmigan Lagopus lagopus, rock sandpiper Calidris ptilocnemis, and American pipit Anthus rubescens . Tall shrub vegetation was important to several species of warblers and sparrows, as well as one species of shorebird (greater yellowlegs Tringa melanoleuca ). We found that point counts augmented with incidental observations provided an almost complete inventory of lowland-breeding species on the study area. These data form a baseline to monitor any future changes in bird distribution and abundance on the Alaska Peninsula.

Alaska↗
USGS2015

Geologic framework of the Alaska Peninsula, southwest Alaska, and the Alaska Peninsula terrane

The Alaska Peninsula is composed of the late Paleozoic to Quaternary sedimentary, igneous, and minor metamorphic rocks that record the history of a number of magmatic arcs. These magmatic arcs include an unnamed Late Triassic(?) and Early Jurassic island arc, the early Cenozoic Meshik arc, and the late Cenozoic Aleutian arc. Also found on the Alaska Peninsula is one of the most complete nonmetamorphosed, fossiliferous, marine Jurassic sedimentary sections known. As much as 8,500 m of section of Mesozoic sedimentary rocks record the growth and erosion of the Early Jurassic island arc. A thinner, but still thick (as much as 5,400 m), sequence of Tertiary sedimentary rocks that are predominantly continental overlies the Mesozoic section. A brief regression in early Tertiary time on the Alaska Peninsula and granodiorite plutonism in the Shumagin, Semidi, and Sanak Islands was followed by deposition of fluvial and minor marine clastic strata. This was followed by deposition of transgressive marine clastic strata and initiation of the Meshik arc, shown by an areally extensive outpouring of volcanic and volcaniclastic rocks and debris between late Eocene and earliest Miocene time. Late Miocene time was marked by another brief transgression and northwest- to southeast-directed compression, followed by renewed volcanism and plutonism which initiated the modern Aleutian magmatic arc. Extensive glacial and glaciomarine deposits of late Pleistocene age create an extensive lowland physiographic province on the northwest side of the Alaska Peninsula and join isolated mountain masses to the Alaska Peninsula on the southwest. Multiple active volcanoes and volcanic peaks dominate the skyline of the Alaska Peninsula and represent the continuation of magmatic activity that has formed the Aleutian arc since late Miocene time. The Alaska Peninsula has had a long and involved history since Paleozoic time. We propose that the Paleozoic and Mesozoic rocks that constitute much of the Alaska Peninsula be called the Alaska Peninsula terrane. Using the concept of subterranes, we divide the terrane into two distinct but tectonically related subterranes: the Chignik and Iliamna subterranes, which share a limited common geologic history. The Iliamna subterrane has served at most times as a source area for the Chignik subterrane; however, some rock units are in common across the subterranes. The Iliamna and Chignik subterranes are in part separated by the Bruin Bay fault system. The Iliamna subterrane is composed of moderately deformed early Mesozoic marine sedimentary and volcanic rocks and schist, gneiss, and marble of Paleozoic(?) and Mesozoic age, and plutonic rocks of the Alaska-Aleutian Range batholith. Characteristic of the Chignik subterrane are little-deformed, shallow-marine to continental clastic sedimentary rocks ranging in age from Permian to latest Cretaceous. However, deep-marine, volcaniclastic, and calcareous rocks form important components of the older rocks in the subterrane. The two subterranes of the Alaska Peninsula terrane are characterized by radically different structural and metamorphic styles. The nonplutonic rocks of the Iliamna subterrane are characterized by metamorphism up to amphibolite-facies grade and intense folding. In the Chignik subterrane, the structural style is dominated by large, open, en echelon anticlinal structures, normal faulting, and thrust and high-angle reverse faults that have minor displacement in a northwest to southeast direction. In the Outer Shumagin and Sanak Islands, rocks assigned to the Chugach terrane are characterized structurally by tight, generally northeast-trending folds. Dips in these rocks tend to be steep, rarely less than 35°, and overturned beds are locally common. The boundaries separating the Alaska Peninsula terrane from other terranes are commonly indistinct or poorly defined. A few boundaries have been defined at major faults, although the extensions of these faults are speculative through some areas. The west side of the Alaska Peninsula terrane is overlapped by Tertiary sedimentary and volcanic rocks and Quaternary deposits.

Alaska↗
USGS2014

Establishing a baseline for regional scale monitoring of eelgrass ( Zostera marina ) habitat on the lower Alaska Peninsula

Seagrass meadows, one of the world’s most widespread and productive ecosystems, provide a wide range of services with real economic value. Worldwide declines in the distribution and abundance of seagrasses and increased threats to coastal ecosystems from climate change have prompted a need to acquire baseline data for monitoring and protecting these important habitats. We assessed the distribution and abundance of eelgrass ( Zostera marina ) along nearly 1200 km of shoreline on the lower Alaska Peninsula, a region of expansive eelgrass meadows whose status and trends are poorly understood. We demonstrate the effectiveness of a multi-scale approach by using Landsat satellite imagery to map the total areal extent of eelgrass while integrating field survey data to improve map accuracy and describe the physical and biological condition of the meadows. Innovative use of proven methods and processing tools was used to address challenges inherent to remote sensing in high latitude, coastal environments. Eelgrass was estimated to cover ~31,000 ha, 91% of submerged aquatic vegetation on the lower Alaska Peninsula, nearly doubling the known spatial extent of eelgrass in the region. Mapping accuracy was 80%–90% for eelgrass distribution at locations containing adequate field survey data for error analysis.

Alaska↗
USGS2013

Age-specific survival of tundra swans on the lower Alaska Peninsula

The population of Tundra Swans (Cygnus columbianus columbianus) breeding on the lower Alaska Peninsula represents the southern extremity of the species' range and is uniquely nonmigratory. We used data on recaptures, resightings, and recoveries of neck-collared Tundra Swans on the lower Alaska Peninsula to estimate collar loss, annual apparent survival, and other demographic parameters for the years 1978–1989. Annual collar loss was greater for adult males fitted with either the thinner collar type (0.34) or the thicker collar type (0.15) than for other age/sex classes (thinner: 0.10, thicker: 0.04). The apparent mean probability of survival of adults (0.61) was higher than that of immatures (0.41) and for both age classes varied considerably by year (adult range: 0.44–0.95, immature range: 0.25–0.90). To assess effects of permanent emigration by age and breeding class, we analyzed post hoc the encounter histories of swans known to breed in our study area. The apparent mean survival of known breeders (0.65) was generally higher than that of the entire marked sample but still varied considerably by year (range 0.26–1.00) and indicated that permanent emigration of breeding swans was likely. We suggest that reductions in apparent survival probability were influenced primarily by high and variable rates of permanent emigration and that immigration by swans from elsewhere may be important in sustaining a breeding population at and near Izembek National Wildlife Refuge.

Alaska↗
USGS2009

Change in abundance of Pacific brant wintering in Alaska: Evidence of a climate warming effect?

Winter distribution of Pacific Flyway brant ( Branta bernicla nigricans ) has shifted northward from low-temperate areas to sub-Arctic areas over the last 42 years. We assessed the winter abundance and distribution of brant in Alaska to evaluate whether climate warming may be contributing to positive trends in the most northern of the wintering populations. Mean surface air temperatures during winter at the end of the Alaska Peninsula increased about 1°C between 1963 and 2004, resulting in a 23% reduction in freezing degree days and a 34% decline in the number of days when ice cover prevents birds from accessing food resources. Trends in the wintering population fluctuated with states of the Pacific Decadal Oscillation, increasing during positive (warm) phases and decreasing during negative (cold) phases, and this correlation provides support for the hypothesis that growth in the wintering population of brant in Alaska is linked to climate warming. The size of the wintering population was negatively correlated with the number of days of strong northwesterly winds in November, which suggests that the occurrence of tailwinds favorable for migration before the onset of winter was a key factor in whether brant migrated from Alaska or remained there during winter. Winter distribution of brant on the Alaska Peninsula was highly variable and influenced by ice cover, particularly at the heavily used Izembek Lagoon. Observations of previously marked brant indicated that the Alaska wintering population was composed primarily of birds originating from Arctic breeding colonies that appear to be growing. Numbers of brant in Alaska during winter will likely increase as temperatures rise and ice cover decreases at high latitudes in response to climate warming.

Alaska↗
USGS2004

Rear-arc vs. arc-front volcanoes in the Katmai reach of the Alaska Peninsula: A critical appraisal of across-arc compositional variation

Physical and compositional data and K-Ar ages are reported for 14 rear-arc volcanoes that lic 11-22 km behind the narrowly linear volcanic front defined by the Mount Katmai-to-Devils Desk chain on the Alaska Peninsula. One is a 30-km3 stratocone (Mount Griggs; 51-63% SiO2) active intermittently from 292 ka to Holocene. The others are monogenetic cones, domes, lava flows, plugs, and maars, of which 12 were previously unnamed and unstudied; they include seven basalts (48-52% SiO2), four mafic andesites (53-55% SiO2), and three andesite-dacite units. Six erupted in the interval 500-88 ka, one historically in 1977, and five in the interval 3-2 Ma. No migration of the volcanic front is discernible since the late Miocene, so even the older units erupted well behind the front. Discussion explores the significance of the volcanic front and the processes that influence compositional overlaps and differences among mafic products of the rear-arc volcanoes and of the several arc-front edifices nearby. The latter have together erupted a magma volume of about 200 km3, at least four times that of all rear-arc products combined. Correlation of Sr-isotope ratios with indices of fractionation indicates crustal contributions in volcanic-front magmas (0.7033-0.7038), but lack of such trends among the rear-arc units (0.70298-0.70356) suggests weaker and less systematic crustal influence. Slab contributions and mantle partial-melt fractions both appear to decline behind the front, but neither trend is crisp and unambiguous. No intraplate mantle contribution is recognized nor is any systematic across-arc difference in intrinsic mantle-wedge source fertility discerned. Both rear-arc and arc-front basalts apparently issued from fluxing of typically fertile NMORB-source mantle beneath the Peninsular terrane, which docked here in the Mesozoic. Springer-Verlag 2004.

Alaska↗
USGS2000

Annual survival and site fidelity of Stellar's Eiders molting along the Alaska Peninsula

Populations of Steller's eiders ( Polysticta stelleri ) molting and wintering along the Alaska Peninsula have declined since the 1960's. We captured and marked a large sample of Steller's eiders molting in 2 lagoons along the Alaska Peninsula between 1975-97. We used mark-recapture analysis techniques to estimate annual survival and movement probabilities within and among lagoons for male and female eiders. Estimates of annual survival (±SE) were 0.899 ± 0.032 for females and 0.765 ± 0.044 for males. Both sexes showed high rates of fidelity to specific molting locations (>95%) within lagoons; yet we found no evidence that annual probability of survival differed among groups molting in different locations either within or among lagoons. We found weak evidence that annual survival decreased between the periods 1975-81 and 1991-97. The lower survival of males compared to females is unusual for waterfowl and may result in a female-biased sex ratio. We conclude that a decrease in adult survival may have initiated the long-term population decline. Further, a shortage of males may be limiting reproductive potential.

Alaska↗
USGS1999

Digital data for the geologic framework of the Alaska Peninsula, southwest Alaska, and the Alaska Peninsula terrane

These digital databases are the result of the compilation and reinterpretation of published and unpublished 1:250,000- and 1:63,360-scale mapping. The map area covers approximately 62,000 sq km (23,000 sq mi) in land area and encompasses much of 13 1:250,000-scale quadrangles on the Alaska Peninsula in southwestern Alaska. The compilation was done as part of the U.S. Geological Survey's Alaska Mineral Resource Assessment project (AMRAP), whose goal was create and assemble geologic, geochemical, geophysical, and other data in order to perform mineral resource assessments on a quadrangle, regional or statewide basis. The digital data here was created to assist in the completion of a regional mineral resource assessment of the Alaska Peninsula. Mapping on the Alaska Peninsula under AMRAP began in 1977 in the Chignik and Sutwik Island 1:250,000 quadrangles (Detterman and others, 1981). Continued mapping in the Ugashik, bristol bay, and northwestern Karluk quadrangles (Detterman and others, 1987) began in 1979, followed by the Mount Katmai, eastern Naknek, and northwestern Afognak quadrangles (Riehle and others, 1987; Riehle and others, 1993), the Port Moller, Stepovak bay, and Simeonof Island quadrangles (Wilson and others, 1995) beginning in 1983. Work in the Cold bay and False Pass quadrangles (Wilson and others, 1992 [Superseded by Wilson and others 1997, but not incorporated herein]) began in 1986. The reliability of the geologic mapping is variable, based, in part, on the field time spent in each area of the map, the available support, and the quality of the existing base maps. In addition, our developing understanding of the geology of the Alaska Peninsula required revision of earlier maps, such as the Chignik and Sutwik Island quadrangles map (Detterman and others, 1981) to reflect this new knowledge. We have revised the stratigraphic nomenclature (Detterman and others, 1996) and our assignment of unit names to some rocks has been changed. All geologic maps on which this compilation is based were published using the Universal Transverse Mercator projection (UTM; Zones 3, 4, and 5). because of the distortions use of the UTM projection would produce on a map of small scale and large area, the plot and graphics files derived from this data are plotted using a more appropriate Albers Equal-area projection for publication.

Alaska↗
USGS1993

Are Bald Eagles important predators of Emperor Geese?

Bald Eagles ( Haliaeetus leucocephalus ) and geese often occur together, especially at sites used by geese for migrational staging and wintering. Although numerous studies have been directed at these taxa, there are only anecdotal accounts (Parris et al. 1980, Bennett and Klaas 1986, Bartley 1988) of Bald Eagles killing healthy geese at any time of the year (but see Raveling and Zezulak 1991). Most species of geese may be too large, as suggested by Shetrod et al. (1976) and Palmer (1988), or they may not regularly allow eagles an advantageous attack position (J.M. Gerrard in litt .). Here we report observations of attacks on Emperor Geese ( Chen canagica ) by Bald Eagles on the Alaska Peninsula in autumn. We discuss these and other observations of eagle-goose interactions vis-a-vis the role of Bald Eagles as predators of Emperor Geese.

Alaska↗
USGS1985

The Meshik Arc: An eocene to earliest miocene magmatic arc on the Alaska Peninsula

The Meshik arc is herein defined to include Eocene to earliest Miocene volcanic and hypabyssal rocks and the associated Meshik and Stepovak Formations of the central Alaska Peninsula. Igneous rocks range from basalt to dacite and yielded K-Ar ages of 48 to 22 m.y. The Meshik arc is oriented along the trend of the Alaska Peninsula, subparallel to the present-day Aleutian arc. Rocks of the Meshik arc are emplaced on Cenozoic, Mesozoic, and older clastic sedimentary rocks of the Alaska Peninsula terrane. Tectonic interpretation suggests: a) the arc represents a relatively stationary period in the otherwise mobile migration of the Alaska Peninsula terrane, b) subduction was an important process along the Alaska Peninsula during Tertiary time, and c) most migration of the Alaska Peninsula terrane since Cretaceous time took place in Paleocene and middle Miocene time.

Alaska↗
USGS1985

Digital image processing techniques for detecting surface alteration - An application on the Alaska Peninsula: A section in The United States Geological Survey in Alaska: Accomplishments during 1983

The tectonic evolution of the Alaska Peninsula makes it a likely area for the discovery of significant mineral deposits. However, because of problems associated with remoteness and poor weather, little detailed mineral exploration work has been carried on there. This study focuses on using Landsat multispectral scanner data for the Port Moller, Stepovak Bay, and Simeon of Island Quadrangles to detect surface alteration, probably limonitic (iron oxide staining) and(or) argillic (secondary clay minerals) in character, that could be indicative of mineral deposits. The techniques used here are useful for mapping deposits that have exposed surface alteration of at least an hectare, the approximate spatial resolution of the Landsat data. Virtually cloud-free Landsat coverage was used, but to be detected, the alteration area must also be unobscured by vegetation. Not all mineral deposits will be associated with surface alteration, and not all areas of surface alteration will have valuable mineral deposits.

Alaska↗
USGS1982

Population and status of Emperor Geese along the north side of the Alaska Peninsula

We gathered information on the timing of spring and autumn migration of Emperor Geese Anser canagicus from Nelson Lagoon, the age ratios of geese during autumn migration, and the numbers of geese in estuaries along the north side of the Alaska Peninsula and Bristol Bay during spring and autumn migration. Birds staged in most of the lagoons and bays along the north side of the Alaska Peninsula, but Nelson Lagoon and Seal Islands Lagoon were the most heavily used. Geese concentrated in Nelson Lagoon for about six to eight weeks in both spring and autumn. We suspect that the population of Emperor Geese in Alaska may have declined by as much as 34% between the 1960's and 1981. Although the average number of young per successful breeding pair has remained high during this period, the overall proportion of young in the population has been extremely low, at least during the past five years. More studies are necessary to determine factors influencing the status of this species.

Alaska↗
USGS1981

Birds of the northcentral Alaska Peninsula, 1976-1980

Between spring 1976 and fall 1980 we studied the occurrence, abundance, and habitat use of birds over a 2000 square km segment of the northcentral Alaska Peninsula. During this period observers were present 473 days and obtained records for all seasons. A total of 125 species was recorded; 63% (79 of 125) were water-associated. The breeding avifauna was found to be a mixture of Panboreal (49%), North American (34%), and Aleutican (17%) species. The Aleutican group was dominant in terms of biomass and numbers of individuals during the nonbreeding period. Forty-two species were confirmed breeding in the area and another 19 were suspected of breeding. The majority of birds occurred as migrants; 14 species were considered permanent residents and an additional 20 were winter residents. ... The area is a principal late summer and fall molting and staging area for several species of arctic and subarctic nesting waders and seaducks and emperor geese .... From late September through mid-October the density of water birds over the entire littoral and nearshore area approached 1000 birds square km. This density was exceeded many fold for certain species on particular segments of habitats in the area.

Alaska↗
USGS1981

Populations, feeding ecology and molt of Steller's Eiders

This study considers the temporal and spatial distribution of Steller's Eiders ( Polysticta stelleri ) during molt along the north side of the Alaska Peninsula from Port Heiden to Bechevin Bay. Subadult eiders molted primarily at Nelson Lagoon, adult males at Nelson Lagoon and Izembek Bay, and adult females primarily at Izembek Bay. Only a few eiders used Bechevin Bay, Seal Islands, and Port Heiden. Although the flightless period overlapped among different age and sex classes, subadults were flightless first, then adult males, and last, adult females. Eiders maintained spatial and temporal separation during the flightless period, thereby reducing competition for food resources. Eiders at Nelson Lagoon were observed feeding only by head-dipping during the pre-flightless period in 1979, a significant change from 1977 when they fed both by diving and dipping. During both 1977 and 1979 eiders foraged for approximately equal amounts of time during each stage of molt. Foods consisted primarily of bivalve mollusks and amphipods. These foods were consumed in different proportions before and after the wing-feather molt, with mussels being most important when eiders were growing remiges. Comparisons between the amount of energy in blue mussels ( Mytilus edulis ), clams ( Macoma balthica ), and gammarid amphipods showed that mussels yield the most energy per gram of whole wet weight. Apparently Steller's Eiders have adjusted to the increased energy demands of molt by eating invertebrates with high caloric content, rather than by increasing the amount of time feeding.

Alaska↗