Oregon Coast Research Articles

Russian views of the unknown coast: Shvetsov's accounts of the Oregon and northern California coastline during the sea otter trade, 1808-09

Early-nineteenth century Russian accounts of the coastline between Alaska and Fort Ross are rare. This article helps fill this gap, providing diary accounts by Russian American Company employee, Afanasy Shvetsov, of two joint Russian-American sea otter hunting trips along the Oregon and northern California coasts in 1808-09. Recently recovered and translated, these accounts aptly describe landscapes and biota, as well as Russian, American, and conscripted Aleut and Kodiak Alutiiq hunters' interactions with Native American communities. Presented in their historical, geographical, and anthropological context, Shvetsov's accounts offer a rare, revealing glimpse of early European encounters with this contact-period coastline.

Daily vulnerability and disaster resilience: a case study of preferred community assets and social capital for Latinx coastal residents

PurposeThis study explores how marginalized populations in high-hazard-risk areas on the Oregon coast utilize valued locations and social networks to adapt to daily challenges and natural hazards.Design/methodology/approachWe hypothesize that locations most valued for their associated resources (community assets) also support the most social capital. Focus group discussions and a novel conceptual mapping activity were employed to identify preferred community assets and associated social capital for Latinx residents.FindingsCommunity-based organizations, churches and schools are the preferred community assets found to enable strong social capital, although differences existed in which forms of structural social capital were identified. Mechanisms by which relationships are formed in this case study and implications for disaster resilience are discussed and theoretically linked to other relevant contexts.Research limitations/implicationsWe provide policy recommendations to utilize community assets and social capital to support disaster resilience for marginalized populations.Originality/valueRecruitment of participants through a community-engaged process developed trust with Latinx community members. Focus group design addressed barriers to participation to create space for diverse perspectives. By applying social capital theory to this data, actionable insights are identified to better incorporate the values and needs of marginalized groups into disaster risk reduction efforts.

Observation of the modal propagation of T waves using distributed acoustic sensing

T waves are low-frequency acoustic-waves (< 100 Hz) generated by earthquakes and propagating in the watercolumn. It is largely accepted that T waves propagate as modes. However, the direct observations of this modal propagation in experimental data remain surprisingly rare. Observation of T waves using distributed acoustic sensing (DAS) makes possible space-sampling with one sensor every few meters over tens of kilometers. Using a simple 2D Fourier transform, the time-space pressure-field can be turned into a frequency-wavenumber field where the propagating wave dispersion curves are revealed. Using freely accessible data from a DAS experiment on the coast of Oregon (USA), we show that the dispersion curves of T waves are consistent with the presence of four propagating modes. The number of modes decreases as expected as T waves propagate shoreward with decreasing depths. The T-wave mode dispersion curves can be fitted by using environmental parameters obtained through ambient noise Scholte wave inversion (also visible in the data).

Regional-scale, high-resolution measurements of hilltop curvature reveal tectonic, climatic, and lithologic controls on hillslope morphology

Climate, tectonics, lithology, and biology are encoded within the morphology of landforms. Hillslopes record uplift and erosion rate through hilltop curvature, in which sharper, more convex hilltops correspond with more rapid erosion rates. However, past hilltop curvature studies that map uplift and erosion rates have been limited to small spatial scales largely due to relatively slow speeds of curvature measurement techniques. This lack of regional-scale observations has made deconvolving the relative contributions of tectonics, climate, and lithology to hillslope morphology a challenge. Here, we used high performance computing and continuous wavelet transforms of topography to rapidly map hilltop curvature in the steep and dissected Oregon Coast Range (OCR) and the adjacent gentler Cascadia Forearc Lowland (CFL) in western Oregon, amounting to ∼43,000 km2 of 1-meter lidar data. We additionally compared mapped hilltop curvature to published erosion rates derived from cosmogenic 10Be, including 11 newly sampled watersheds. We observed that hilltops are systematically sharper in the OCR than in the CFL, and we noted a linear relationship between catchment-averaged erosion rate and hilltop curvature, consistent with previous observations and theory that erosion rate scales linearly with hilltop curvature in soil-mantled landscapes. The boundary between the OCR and CFL, as demarcated by hilltop curvature, is often abrupt and occurs across mapped structures that separate disparate baselevels but where lithology and mean annual precipitation remain constant. Thus, while we observed significant variability in hilltop curvature that results from secondary lithologic and climatic controls, our results demonstrate that hillslope morphology in western Oregon is set primarily by uplift via tectonically-controlled baselevel lowering rates. These regional interpretations additionally highlight the computational advantages of the wavelet transform for rapidly quantifying hilltop curvature.

Ocean conditions influence the quality of recruiting benthic marine invertebrate larvae—Insights from fatty acids

AbstractMany marine benthic invertebrates have a pelagic life stage, during which larvae need to accumulate enough reserves to complete metamorphosis to a settled benthic juvenile. Currently, very little is known about how ocean conditions affect quality of the larvae. We studied this for three settlement seasons (2017–2019) by collecting returning Dungeness crab (Metacarcinus magister) megalopae at the Oregon coast and analyzing them for fatty acid biomarkers. We found that the larvae are omnivorous and have versatile diets. The daily larval abundance was positively correlated with larval quality. Despite the relatively high day‐to‐day variation, we found pronounced seasonal and inter‐annual differences in the body condition (size and total fatty acid content) and biomarker composition of megalopae. Especially, the early season recruits of 2017 had lower content of lipids and polyunsaturated fatty acids known to be beneficial to crustaceans. This is likely related to lingering effects of the eastern Pacific marine heat wave (2014–2016) on pelagic communities. The larvae were rich in docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) with lower levels in benthic juveniles, indicating an ontogenetic diet shift and likely lower availability of DHA and EPA in the benthic environment. The pulsed megalopa recruitment may provide substantial carbon and lipid inputs to the nearshore ecosystem as a form of pelagic subsidy. Our results reveal that ocean conditions may have an effect on the quality of returning larvae, which likely influence their recruitment performance and early juvenile success, and thus potentially also the population size and commercial catch 4 yr later.

How tourists ‘escaping the heat’ may drive future increases in municipal water demand in Oregon coastal communities

Little is known about the effect of future weather and climate on municipal water demand in coastal communities with tourist-centric economies. To address this knowledge gap, we used an econometric model of monthly water demand that allowed for non-linear responses to weather variables to estimate temperature-response functions for demand from a sample of communities in the Oregon Mid-Coast. A main result is that local temperature was not a significant driver of variability in monthly water demand but that temperature in the Willamette Valley—the source of most tourists to the Oregon coast—was. We assumed that the increase in demand in response to higher Willamette Valley temperature arose from an increase in tourists escaping the heat in the Willamette Valley for cooler conditions on the coast. Applying the temperature response functions to scenarios of future climate to the year 2070 led to projected increases in water demand independent of other factors. Whether future tourism is either constrained by the local resident population that serves tourism or is constrained by the potential tourist population in the Willamette Valley, the climate-change contribution to projected water demand is generally of comparable magnitude to—if not greater than—the contribution from resident population change alone over the next 50 years. For communities where the population is projected to decline, the climate effect may more than offset the effect of declining population, resulting in a net positive change in demand.

Assessing the value of harmful algal bloom forecasts in the Pacific Northwest

Abstract Over the past three decades, fisheries and livelihoods on the coasts of Washington and Oregon have been severely impacted by the presence of harmful algal blooms (HABs) that produce domoic acid, a neurotoxin that accumulates in shellfish and endangers public health. Among others, recreational razor clams and commercial Dungeness crab fisheries along the Pacific Northwest (PNW) have been negatively affected, jeopardizing the economies of coastal communities that depend on tourist revenues and income generated through visits of harvesters in the region. The PNW HAB Bulletin, launched in 2008, publishes forecasts on incoming HAB events, which has enabled managers to increase toxin monitoring in high-risk locations and proceed with selected harvesting at safe beaches and delays or closures of fishing seasons, as required. In light of the value of the HAB Bulletin to local managers and communities and the occasional challenges of securing sufficient resources to ensure its continuation, this study attempts to assess the value of information (VOI) for the predictions provided by the Bulletin. Results of the study show that ongoing financial support of the Bulletin is economically justifiable. The value of HAB forecast is positively related to three primary factors: the frequency of HAB events, the precision of forecast, and the number of social and economic sectors benefiting from the forecast. The expected increase in HAB frequency and intensity due to climate change, coupled with advancements in forecasting accuracy through technological development, is anticipated to enhance the value of the forecast program.

RegionGrow3D: A Deterministic Analysis for Characterizing Discrete Three‐Dimensional Landslide Source Areas on a Regional Scale

AbstractRegional‐scale characterization of shallow landslide hazards is important for reducing their destructive impact on society. These hazards are commonly characterized by (a) their location and likelihood using susceptibility maps, (b) landslide size and frequency using geomorphic scaling laws, and (c) the magnitude of disturbance required to cause landslides using initiation thresholds. Typically, this is accomplished through the use of inventories documenting the locations and triggering conditions of previous landslides. In the absence of comprehensive landslide inventories, physics‐based slope stability models can be used to estimate landslide initiation potential and provide plausible distributions of landslide characteristics for a range of environmental and forcing conditions. However, these models are sometimes limited in their ability to capture key mechanisms tied to discrete three‐dimensional (3D) landslide mechanics while possessing the computational efficiency required for broad‐scale application. In this study, the RegionGrow3D (RG3D) model is developed to broadly simulate the area, volume, and location of landslides on a regional scale (≥1,000 km2) using 3D, limit‐equilibrium (LE)‐based slope stability modeling. Furthermore, RG3D is incorporated into a susceptibility framework that quantifies landsliding uncertainty using a distribution of soil shear strengths and their associated probabilities, back‐calculated from inventoried landslides using 3D LE‐based landslide forensics. This framework is used to evaluate the influence of uncertainty tied to shear strength, rainfall scenarios, and antecedent soil moisture on potential landsliding and rainfall thresholds over a large region of the Oregon Coast Range, USA.

Evaluating Abiotic and Biotic Predictors of Coastal Giant Salamander (Dicamptodon tenebrosus) Populations in Fish-Bearing Headwaters of the Oregon Coast Range

Evaluating Abiotic and Biotic Predictors of Coastal Giant Salamander (Dicamptodon tenebrosus) Populations in Fish-Bearing Headwaters of the Oregon Coast Range

Cutthroat trout responses to increased light via conventional and alternative riparian buffers

Forested headwaters, particularly in the Pacific Northwest, USA, are typically heavily shaded by dense stands of riparian vegetation. Reduced riparian cover can occur from natural or anthropogenic events, resulting in increased light which can increase fish biomass by promoting in-stream food resources. We conducted a 5 y before-after-control-impact (BACI) study on 10 small streams in the Oregon Coast Range, USA, and investigated how changes to the magnitude of stream light, mediated by conventional and alternative riparian buffer configurations adjacent to upland timber harvest, changed Coastal Cutthroat Trout (Oncorhynchus clarkii clarkii) abundance, biomass, bioenergetics, diet composition, and the availability of aquatic food resources. Riparian buffer treatments reduced canopy cover as much as 34 % cover (98–99 % pre; 64–98 % post-treatment) and enhanced total available sunlight reaching the stream surface by 8–31 % relative to unharvested references that only changed by 3–4 %. In the first year following the treatments, young-of-year trout (YOY, age 0) densities changed by between +0.1 and +0.78 #/m2 in treatment streams while densities changed by –0.001 and +0.02 #/m2 at reference streams. Although change in YOY densities was positively correlated with change in stream light (rs=0.81, p=0.02), changes in basal resources (periphyton and macroinvertebrates) were both positive and negative and did not increase with change in stream light. Adult (age 1+) trout responses were mixed in the first year post-treatment, but changed by –0.14 to +0.24 #/m2 at treatment sites (–0.02 to –0.05 at reference sites) in the second year post-treatment, likely due to increased recruitment from the strong cohort of YOY in the first year. Bioenergetics analysis in one post-treatment year showed that adult trout did not experience greater summer growth (–0.003 to +0.0005 g g−1 d−1) or proportions of maximum consumption (0.18–0.25) in streams with more light than at reference streams (–0.001 and +0.001 g g−1 d−1, 0.19 and 0.23). Overall, while standing stock assessments suggest that fish showed some increases after experimental treatments that increased light, our data did not provide the clear mechanistic evidence for bottom-up drivers that was expected. The relationship between canopy removal and fish production is not always predictable in small headwater streams, and even though fish populations were generally resilient to riparian manipulation, evaluations of terrestrial food resources, the dynamic between canopy cover and light reaching the stream, and changes to temperature may lend valuable insight on the impacts to fish populations.

Archaeology and ethnobiology of Late Holocene bird remains from the northern Oregon coast

Archaeology and ethnobiology of Late Holocene bird remains from the northern Oregon coast

As the Neighborhood Changes So Do We: Changing with Community

ABSTRACT To truly fulfill their missions and make positive strides toward the conservation of our ocean, aquariums need to reach diverse audiences and reflect their local communities. Reaching audiences not adequately represented at our facilities takes work and time. It requires building relationships and trust. We need to understand which audiences are not represented and why, and work with them to make our aquariums more inclusive and welcoming. The Oregon Coast Aquarium's efforts to better engage our local Latino community are a work in progress. However, we have made some positive strides and our continuing work can help inform others of the inherent opportunities and struggles that are part of this process.

Geoarchaeological Record of the AD 1700 Cascadia Subduction Zone Earthquake and Tsunami at the Salmon River Wet Site, Central Oregon Coast

Geoarchaeological Record of the AD 1700 Cascadia Subduction Zone Earthquake and Tsunami at the Salmon River Wet Site, Central Oregon Coast

Chemical Compositions and Enantiomeric Distributions of Foliar Essential Oils of Chamaecyparis lawsoniana (A. Murray bis) Parl, Thuja plicata Donn ex D. Don, and Tsuga heterophylla Sarg.

As part of our continuing interest in the essential oil compositions of gymnosperms, particularly the distribution of chiral terpenoids, we have obtained the foliar essential oils of Chamaecyparis lawsoniana (two samples), Thuja plicata (three samples), and Tsuga heterophylla (six samples) from locations in the state of Oregon, USA. The essential oils were obtained via hydrodistillation and analyzed by gas chromatographic techniques, including chiral gas chromatography-mass spectrometry. The major components in C. lawsoniana foliar essential oil were limonene (27.4% and 22.0%; >99% (+)-limonene), oplopanonyl acetate (13.8% and 11.3%), beyerene (14.3% and 9.0%), sabinene (7.0% and 6.5%; >99% (+)-sabinene), terpinen-4-ol (5.0% and 5.3%; predominantly (+)-terpinen-4-ol), and methyl myrtenate (2.0% and 5.4%). The major components in T. plicata essential oil were (-)-α-thujone (67.1-74.6%), (+)-β-thujone (7.8-9.3%), terpinen-4-ol (2.7-4.4%; predominantly (+)-terpinen-4-ol), and (+)-sabinene (1.1-3.5%). The major components in T. heterophylla essential oil were myrcene (7.0-27.6%), α-pinene (14.4-27.2%), β-phellandrene (6.6-19.3%), β-pinene (6.4-14.9%; >90% (-)-β-pinene), and (Z)-β-ocimene (0.7-11.3%). There are significant differences between the C. lawsoniana essential oils from wild trees in Oregon and those of trees cultivated in other geographical locations. The essential oil compositions of T. plicata are very similar, regardless of the collection site. There are no significant differences between T. heterophylla essential oils from the Oregon Coastal Range or those from the Oregon Cascade Range. Comparing essential oils of the Cupressaceae with the Pinaceae, there are some developing trends. The (+)-enantiomers seem to dominate for α-pinene, camphene, sabinene, β-pinene, limonene, terpinen-4-ol, and α-terpineol in the Cuppressaceae. On the other hand, the (-)-enantiomers seem to predominate for α-pinene, camphene, β-pinene, limonene, β-phellandrene, terpinen-4-ol, and α-terpineol in the Pinaceae.

Passive acoustic monitoring and convolutional neural networks facilitate high-resolution and broadscale monitoring of a threatened species

Population monitoring is an essential component of biodiversity conservation and management, but low detection probabilities for rare and/or cryptic species makes estimating abundance and occupancy challenging. Passive acoustic monitoring combined with machine learning algorithms represents a potential path forward to effectively and efficiently monitor the occurrence of rare vocalizing species across entire forest landscapes. Our objectives were to develop and implement a convolutional neural network (PNW-Cnet) to identify vocalizations of a rare and threatened forest nesting bird species – the marbled murrelet (Brachyramphus marmoratus) – in the Pacific Northwest, U.S.A., 2018–2021. We used PNW-Cnet predictions from broadscale passive acoustic monitoring data to examine spatiotemporal patterns in the distribution of murrelets. PNW-Cnet showed sufficiently high prediction accuracy (overall precision > 0.9) to enable broadscale population monitoring. Spatiotemporal analysis showed that annual peak murrelet call abundance occurs in ordinal weeks 28–32 (late July–Mid August) but this varied by study area. The greatest number of detections typically occurred in the Olympic Peninsula and Oregon Coast Range where late-successional forest dominates and nearer to ocean habitats. We demonstrate that passive acoustic monitoring can be used to understand intensity of use across broad scales for a rare and cryptic species in addition to the typical detection/non-detection data that are often collected. Passive acoustic monitoring combined with PNW-Cnet offers considerable promise for species distribution modeling and long-term population monitoring for rare species.

Seasonal variability in energetic value of Crangon alaskensis and effects of marine heatwaves in the Northeast Pacific Ocean

Research cruises were conducted to sample the invertebrate community along the shelf off the central coast of Oregon from 2010 to 2018. A large marine heatwave (MHW) hit the northeast Pacific in fall 2014 and persisted locally through 2015. Here, we assessed the caloric content changes of Crangon alaskensis (a common sandy shrimp) before, during, and after the 2014–2015 MHW. We found significant reductions in the caloric density of shelf populations of C. alaskensis during summer 2015. Oceanographic indices like the Biologically Effective Upwelling Transport Index (BEUTI) and the Pacific Decadal Oscillation (PDO) had greater predictive power for caloric density and biomass than in situ conditions, although bottom temperature and dissolved oxygen were also significantly correlated with caloric density. Caloric density of C. alaskensis was highest in 2018, indicating favorable conditions after the intense MHW of 2014–2015 allowed the caloric density to rebound.

The faecal microbiome of the Pacific banana slug, Ariolimax columbianus, displays seasonal variation

ABSTRACT The Pacific banana slug, Ariolimax columbianus, is the largest land mollusc in North America and occurs in forests ranging from northwestern California to Alaska. We explored the microbial community found within the faeces of 24 slugs from the Oregon Coast Range. Twenty-four slugs were collected in 2019, 12 in the spring and 12 in the fall. These two time points were selected to investigate the composition of microbial populations in wild-caught slugs, also in response to seasonal changes in available plants as food sources. Results from 16S rRNA gene amplicon sequencing indicate that the most prevalent phyla detected from A. columbianus were Proteobacteria (66%) and Bacteriodetes (16%), similar to previous observations from six other species/genera of terrestrial gastropods (Stylommatophora). The most abundant operational taxonomic units across all specimens were Enterobacter sp., Pseudomonas sp. and Flavobacterium sp. Significant seasonal variation was observed for several species of Flavobacteriales, Firmicutes and Proteobacteria, with the majority showing higher abundance in fall. In contrast to Cornu aspersum (previously Helix aspersa, parapatric with A. columbianus) and Geomaculus maculosus, A. columbianus harbours very low levels of Buttiauxella (0.35%). These findings raise questions about the origin, specificity and selection of specific bacteria as components of the intestinal microbiome of terrestrial gastropods.

Automated detection of fin whale calls recorded with distributed acoustic sensing

As the global biodiversity crisis intensifies, wildlife monitoring has become a necessity. From an oceanographic perspective, the tracking of baleen whales allows studies of their habitat use and can support call density estimates, which are indicative of ocean health. Distributed Acoustic Sensing (DAS) is a promising observational technique that measures strain rates along a spare optical fiber with a spatial resolution of tens of meters to distances of ∼100 km. Over 4-days in November 2021, a public domain DAS dataset was collected on the submarine cables of the Ocean Observatories Initiative Regional Cabled Array off the coast of central Oregon. The experiment recorded the acoustic signals from tens of thousands of fin whale calls as well as blue whale calls, ship signals and T-phases. We will describe preliminary efforts to develop automated methods to detect and localize fin whale calls using small representative examples of the DAS data. Our longer-term goal is to extend this approach to the full data set to understand the sensitivity of DAS to fin whale calls as function of cable geometry and seafloor characteristics and to study the distribution of calling fin whales in coastal waters off central Oregon. [Work supported by ONR.]

A comparison of two snapshot studies half a century apart suggests stability in a Pacific Northwest winter forest bird community

Populations of many North American bird species have declined throughout the past half century. The majority of studies quantifying these declines have analyzed counts of birds taken during spring and summer, not during the season of scarcity, winter. We re-surveyed seven large study plots in Douglas fir (Pseudotsuga menziesii) forests initially surveyed in winter during the late 1960s in the Oregon Coast Range, USA. We compared density estimates, observed species richness and vegetation structure within plots, and inspected aerial photography to describe changes in landscape-level landcover. To assess potential drivers of change, we reviewed historical climate data and explored patterns of abundance associated with forest age. Observed species richness was greater in the modern surveys. Abundances of four of the six most common bird species appeared to be similar to or slightly lower than 50 years ago as the historical point estimates usually fell within or above 95% confidence intervals generated from our analyses. We found no clear associations with changes in bird communities and forest structure, climate, or forest age. The historical data are unique in providing point estimates of abundance for the entire bird community on each study plot. Yet, some uncertainties in accuracy of the historic counting methods could still influence interpretation of multi-decadal changes in apparent abundance. We conclude that this Pacific Northwest bird community was relatively stable in its abundances of the most common forest-dwelling species and that largely the communities are still intact. Additional production of precisely repeatable surveys of winter bird communities are needed in all habitats to adequately characterize long-term population dynamics during the season of scarcity.

Short communication: Cosmogenic noble gas depletion in soils by wildfire heating

Abstract. Measurements of cosmic-ray-produced beryllium-10, neon-21, and helium-3 in quartz in a soil profile from a forested landscape in the Oregon Coast Range show that the cosmogenic noble gases 21Ne and 3He are depleted relative to 10Be in the shallow subsurface. The noble gases are mobile in mineral grains via thermally activated diffusion and 10Be is not, implying that noble gas depletion is the result of surface heating by wildfires and subsequent mixing of partially degassed quartz downward into the soil. Cosmogenic noble gas depletion by wildfire heating of soils is a potential means of estimating wildfire intensity and/or frequency over pre-observational timescales.