Siuslaw River Research Articles

Pedogenic pathways and deep weathering controls on soil organic carbon in Pacific Northwest forest soils

Characterizing the distribution and dynamics of organic carbon in soil is critical for quantifying changes in the global carbon cycle. In particular, weathering controls on near-surface and deep (>1 m) soil organic carbon (SOC) dynamics have been proposed but limited data prevents us from predicting SOC over topographically complex landscapes and quantifying how changes in climate and perturbations, such as wildfire or land management, influence SOC stocks. To advance our understanding of how weathering alters soil geochemistry and influences SOC storage, we synthesize previous data with a new analysis of the Siuslaw River soil chronosequence from terraces in the Oregon Coast Range, a region that harbors the richest SOC inventories in the continental US. We analyze how the relationships between soil geochemistry, physical properties, and SOC storage vary with weathering status and pathways across soils that span 0.041 to 990 kyr and vary in depth from 1 m to >10 m. To distinguish the key properties and processes influencing SOC storage at different depths, we break our analysis into three depth intervals: 0–30, 30–100, and >100 cm. Our results suggest that the processes that control SOC stocks vary systematically with time and depth owing to weathering impacts on soil properties and pedogenic development. At 30 kyr we observe a peak in SOC stock in the top 100 cm coincident with a peak in oxalate extractable Al and Fe concentrations, representing secondary poorly crystalline minerals, which is consistent with previous studies. We also observe a decline in shallow SOC stock for >30 kyr soils as poorly crystalline minerals are replaced by more stable crystalline forms and soils become clay dominated. At 120 kyr, SOC below 100 cm starts to contribute significantly to the total SOC profile inventory and by 990 kyr, this fraction composes >40% of the total SOC stock. Taken together, our results indicate that total SOC stock increases with soil age as the increased intensity of bedrock weathering deepens the critical zone, creating accommodation space for deep SOC storage. These findings reveal the intimate link between poorly crystalline minerals and SOC and suggest that systematic analysis of soil development in the critical zone provides a first-order constraint on SOC stocks.

Geologic controls on paleodrainage incision and morphology during sea level lowstands on the Cascadia shelf in Oregon, USA

The lowstand extensions of two fluvial systems from the Cascadia subduction margin are investigated using high-resolution seismic reflection data to determine the relative controls on paleodrainage morphology. We document distinct differences between the two systems, located ~40 km apart, attributed to underlying structure and lithology, shelf gradient, and drainage basin characteristics. A cross-shelf valley exists for only one of the drainage systems, the Umpqua River. The outer shelf part of the valley is a syncline, which formed a natural structural low for lowstand drainage, while the inner shelf part of the valley exhibits incision and is associated with a mid-shelf convex change is slope. The other drainage system, the Siuslaw River, did not develop an across-shelf valley and is only denoted in the seismic data by an erosional subaerial unconformity. Structural trends are perpendicular to cross-shelf drainage, supporting a more anastomosing stream morphology for the paleo-Siuslaw. The shelf edge for this system was not exposed for a long period of time during the last lowstand, preventing substantial outer shelf incision. Differences in fluvial elevation, discharge, and hinterland geology, also played a role in the cross-shelf morphologies of the paleo-Umpqua and paleo-Siuslaw. These results highlight how controls on lowstand paleodrainage morphology can change over short distances on an active margin.

Groundwater Surface (GWS) Mapping by Ground Penetrating Radar (GPR) For Use in Protecting Freshwater Habitats, Water Quality, and Active Dune Landscapes, In the Florence Coastal Dune Sheet, Oregon, USA

Ground penetrating radar (GPR) profiling was performed in the Florence (FLOR) coastal dune sheet to test relations between remotely-sensed groundwater surface (GWS) trends, measured groundwater phreatic surfaces, and overlying freshwater features/habitats. Following preliminary GPR testing, the GWS trend mapping was employed in the north FLOR dune aquifer (17 km in length and 5 km in width), in anticipation of increasing development pressures on aquifer groundwater withdrawal by the City of Florence, Oregon. Several available technologies, including continuously-towed GPR profiling (5-8 km/hr), real-time GPS positioning (±2 m horizontal), Lidar elevation control (±0.5 m NAVD88), and GIS mapping/surface trend analyses permitted upscaling to the large management area (40 km2) in the north FlOR dune aquifer. Totals of 95 km of GPR track-line, including 943 averaged shot points at 100 m track-line intervals (total ~100,000 shot points), were collected during a three-week field effort. The remotely sensed GWS, ranging from 1 to 14 m depth subsurface and 0 to 57 m elevation NAVD88, was ground-truthed in ponds, gaining-stream reaches, and monitored water wells. An area wide groundwater surface map confirmed a modeled dune-ramp aquifer, sloping (0.5-2.0 % gradients) to the Pacific Ocean shoreline and the dividing Siuslaw River valley. The continuous GPR profiles connected large dune barrage lakes, interdune valley window lakes, anadromous fish passage streams, and sensitive bog habitats to the locally-variable GWS (0.98 R2 correlation coefficient). These elevated freshwater features were shown not to be developed on perched dune soil aquitards or lake bottom mud seals, but rather they are directly dependent on the mounded, variably sloping, and very-shallow GWS in the regional dune aquifer. Shallow GWS depths also promote colonization of active dune surfaces by non-native invasive dune grasses. The freshwater lakes and ponds were shown to be susceptible to contaminant transport by down-gradient GWS flows from surrounding residential and resort development.

Cephalopod remains from stomachs of sperm whales (Physeter macrocephalus) that mass‐stranded along the Oregon coast

AbstractOn 16 June 1979, a herd of 41 sperm whales stranded near the mouth of the Siuslaw River in Florence, Oregon. The stomach contents from 32 whales were collected, identified to the lowest taxonomic level possible, enumerated, and measured. A total of 20,247 cephalopod lower beaks that represented 24 species from 14 different families were recovered. The most numerous species wereHistioteuthis hoylei(25.9%),Taonius borealis(12.9%),Galiteuthis phyllura(11.2%),Gonatopsis/Berryteuthistype (10.9%), andMoroteuthis robusta(10.7%). Reconstructed estimates of mass indicated thatM. robustacontributed almost 50% of the total mass of cephalopods consumed, followed byH. hoylei(19.3%), andT. borealis(7.0%). The most important species in the diet of stranded whales wereM. robusta,H. hoylei,T. borealis,G. phyllura,Octopoteuthis deletron, andGonatopsis/Berryteuthistype. There were significant differences in the diet of males and females, but no differences between sperm whales of different age groups. Overall, sperm whales primarily consumed small cephalopods that were likely eaten south of 45ºN in or near the California Current System. This study provides new estimates of the food habits of sperm whales in the northeast Pacific from one of the largest strandings of this species.

Genetic diversity, endemism and phylogeny of lampreys within the genus Lampetra sensu stricto (Petromyzontiformes: Petromyzontidae) in western North America

Phylogenetic structure of four Lampetra species from the Pacific drainage of North America (western brook lamprey Lampetra richardsoni, Pacific brook lamprey Lampetra pacifica, river lamprey Lampetra ayresii and Kern brook lamprey Lampetra hubbsi) and unidentified Lampetra specimens (referred to as Lampetra sp.) from 36 locations was estimated using the mitochondrial cytochrome b gene. Maximum parsimony and Bayesian inferences did not correspond with any taxonomic scheme proposed to date. Rather, although L. richardsoni (from Alaska to California) and L. ayresii (from British Columbia to California) together constituted a well-supported clade distinct from several genetically divergent Lampetra populations in Oregon and California, these two species were not reciprocally monophyletic. The genetically divergent populations included L. pacifica (from the Columbia River basin) and L. hubbsi (from the Kern River basin) and four Lampetra sp. populations in Oregon (Siuslaw River and Fourmile Creek) and California (Kelsey and Mark West Creeks). These four Lampetra sp. populations showed genetic divergence between 2.3 and 5.7% from any known species (and up to 8.0% from each other), and may represent morphologically cryptic and thus previously undescribed species. A fifth population (from Paynes Creek, California) may represent a range extension of L. hubbsi into the Upper Sacramento River.

Coastal subsidence in Oregon, USA, during the giant Cascadia earthquake of AD 1700

Quantitative estimates of land-level change during the giant AD 1700 Cascadia earthquake along the Oregon coast are inferred from relative sea-level changes reconstructed from fossil foraminiferal assemblages preserved within the stratigraphic record. A transfer function, based upon a regional training set of modern sediment samples from Oregon estuaries, is calibrated to fossil assemblages in sequences of samples across buried peat-mud and peat-sand contacts marking the AD 1700 earthquake. Reconstructions of sample elevations with sample-specific errors estimate the amount of coastal subsidence during the earthquake at six sites along 400 km of coast. The elevation estimates are supported by lithological, carbon isotope, and faunal tidal zonation data. Coseismic subsidence at Nehalem River, Nestucca River, Salmon River, Alsea Bay, Siuslaw River and South Slough varies between 0.18 m and 0.85 m with errors between 0.18 m and 0.32 m. These subsidence estimates are more precise, consistent, and generally lower than previous semi-quantitative estimates. Following earlier comparisons of semi-quantitative subsidence estimates with elastic dislocation models of megathrust rupture during great earthquakes, our lower estimates for central and northern Oregon are consistent with modeled rates of strain accumulation and amounts of slip on the subduction megathrust, and thus, with a magnitude of 9 for the AD 1700 earthquake.

Using soil residence time to delineate spatial and temporal patterns of transient landscape response

On hillslopes the balance between soil transport and production determines local soil thickness and the age distribution of particles that comprise the soil (where age refers to the time elapsed since detachment from bedrock). The mean of this age distribution is defined as the residence time, and in a landscape with time‐invariant topography (i.e., morphologic steady state), the spatial uniformity of soil production ensures that the residence time of soils is spatially invariant. Thus, given constant soil‐forming factors, spatial variation of soil properties reflects differences in residence time driven by nonuniform soil production. Spatially extensive soil databases, which are often freely available in electronic form, provide a cheap and accessible means of analyzing patterns of soil residence time and quantifying landscape dynamics. Here we use a soil chronosequence to calibrate a chronofunction describing the reddening of soils in the Oregon Coast Range, which is then used to quantify the spatial distribution of soil residence time. In contrast to the popular conception that the Oregon Coast Range experiences uniform erosion, we observe systematic variations in soil residence time driven by stream capture, deep‐seated landsliding, and lateral channel migration. Large, contiguous areas with short residence time soils (hue 10YR) occur west of the Siuslaw River–Long Tom Creek drainage divide, whereas soil patches with redder hues of 7.5YR or 5YR indicate longer residence times and transient landscape conditions. These zones of red soils (5YR) occur east of the Siuslaw–Long Tom divide, coinciding with low‐gradient ridge and valley topography and deeply alluviated valleys resulting from drainage reversal in the Quaternary. Patches of red soils are also associated with deep‐seated landslides at various locations in our study area. Our calculated soil residence times appear subject to overestimation resulting from limitations of the simple weathering index used here and chronofunction calibration uncertainties. Nonetheless, our soil residence time estimates appear accurate to within an order of magnitude and provide a useful constraint on landscape dynamics over geomorphic timescales.

Recent ventifact development on the central Oregon coast, western USA

AbstractThe unusual location of ventifacts, on a boulder‐built jetty at the mouth of the Siuslaw River, Oregon coast, western USA, allows ventifact age and wind abrasion rates to be estimated with some precision. The jetty was built mainly between 1892–1901 and extended throughout the twentieth century. Consideration of historical shoreline position and the history of jetty construction and repair suggests the ventifacts have formed since about 1930.Morphologically the ventifacts are aligned south‐to‐north reflecting winter winds and sediment transport from the adjacent beach. Wind‐parallel grooves and ridges with sharp, sinuous crests are developed on inclined boulder surfaces on top of the jetty and reflect suspended sand transport in wind vortices. Deeply pitted surfaces on steep boulder surfaces nearest the beach reflect impact by saltating sand grains.Based on present wind regimes (1992–2000) from three regional weather stations, southerly winds above the sand transport threshold occur for 21·9–29·6 per cent of the time. Based on estimated depth of loss from boulder surfaces, wind abrasion rates are calculated to be on the order of 0·24–1·63 mm a−1. This is the first well‐constrained field estimate of ventifact age and ventifaction rate from a modern coastal environment. Copyright © 2003 John Wiley & Sons, Ltd.

Effect of Acclimation on the Homing and Survival of Hatchery Winter Steelhead

Abstract We evaluated prerelease acclimation of hatchery winter steelhead Oncorhynchus mykiss in Whittaker Creek, a tributary of the Siuslaw River, Oregon, as a management strategy to attract returning adults to a release site where they could be removed. The objective was to reduce the number of hatchery fish in wild steelhead spawning areas while providing hatchery steelhead for recreational fisheries. We found no significant difference in homing rate or survival between hatchery steelhead acclimated for 30 d and those trucked from the hatchery and directly released. For the 1991–1993 broods, a mean of 92% of directly released fish and 97% of acclimated fish were accounted for in Whittaker Creek. In contrast, 15% of adults from hatchery smolts released at four traditional sites in the main-stem Siuslaw River were accounted for in Whittaker Creek. The spatial distribution of the catch in recreational fisheries was similar for the direct and acclimated groups; that catch, however, was nearer Whittaker Cre...

Chromosomal NOR Karyotypes and Genome Size Variation among Squawfishes of the Genus Ptychocheilus (Teleostei: Cyprinidae)

Nucleolus organizer region (NOR) chromosomes from species of the North American cyprinid genera Ptychocheilus, Mylopharodon, and Lavinia were documented and tested for presumed homology using trypsin G-banding. Four species of Ptychocheilus (P. lucius, P. grandis, P. umpquae, and P. oregonensis), M. conocephalus, and L. exilicauda possessed two pair of NOR-bearing chromosomes with the NORs situated terminally on the short arms of medium-sized acrocentric chromosomes (NOR phenotype A). Both pair of NOR chromosomes in all three genera were identical in trypsin G-banding pattern and hence were uninformative for inference of phylogenetic relationships within Ptychocheilus. The apparent conservatism of chromosomal NOR evolution in these cyprinid genera from western North America is in striking contrast to that documented among cyprinids from eastern North America. Genome sizes (DNA contents) of the six species also were documented using flow cytometry. Heterogeneity tests revealed three homogeneous groups of samples: (1) L. exilicauda, P. lucius, P. grandis, and P. umpquae from the Siuslaw River with low genome sizes; (2) M. conocephalus with an intermediate genome size; and (3) P. oregonensis and P. umpquae from the Umpqua River drainage with high genome sizes. The difference in genome size between P. umpquae from the Siuslaw and Umpqua river drainages is greater than that found, on average, between any two North American cyprinid species drawn at random. The difference in genome size, coupled with morphological differences documented previously, suggests that P. umpquae from the two drainages may represent distinct species. Using an optimization procedure, genome sizes were partitioned among branches of two contrasting hypotheses of relationships in Ptychocheilus. The hypothesis of {P. lucius [P. grandis (P. umpquae, P. oregonensis)]} required about 20% less change in genome size (i.e., was more parsimonious) than the hypothesis of {P. oregonensis [P. umpquae (P. grandis, P. lucius)]}.

Physiological Changes during Seaward Migration of Wild Juvenile Coho Salmon (Oncorhynchus kisutch)

Peaks in migration of wild juvenile coho salmon (Oncorhynchus kisutch) from Knowles Creek (Siuslaw River, Oregon) occurred in November and May. Condition factor of nonmigrant fish was higher than migrants or captives throughout the study. Skin guanine levels of migrant fish rose sharply during the first 2 wk of April and continued to rise through June. Gill (Na + K)-ATPase specific activity of migrants rose gradually from a low in January to a maximum in June. Gill (Na + K)-ATPase activity of migrants and nonmigrants was low and not significantly different during November to mid-March. During April, however, gill ATPase activity of migrants rose to become significantly higher than that of nonmigrants until the first 2 wk of May. Cyclic changes in gill (Na + K)-ATPase activity was not observed in these fish. Gill (Na + K)-ATPase activity of fish reared in a laboratory was similar to that of wild nonmigrants until it peaked during the last 2 wk of April, after which the specific activity was lower than either migrants or nonmigrants.

A MASS STRANDING OF SPERM WHALES IN OREGON: SEX AND AGE COMPOSITION OF THE SCHOOL

AbstractA school of 41 sperm whales, Physeter macrocephalus, that stranded near the mouth of the Siuslaw River, Oregon (43°59′N, 124°08′W), on 16 June 1979 consisted of 13 males and 28 females. Their ages were estimated by assuming that each postnatal dentin layer represents one year. The males were all sub‐adults, 9.3–11.5 m long and 14–21 yr old. The females were 9.3–11.4 m long, and 11 to about 58 yr old. Ten females were dissected; nine were sexually mature and three were carrying fetuses 2.64–4.62 m long. None of the 28 females was visibly lactating.

Oregon Coast Shoreline Changes Due to Jetties

Patterns of beach erosion and accretion due to jetty construction are examined for the Oregon coast which has a seasonally reversing littoral drift with a zero or near zero net drift. Thus the shoreline changes do not result from the jetties blocking a net drift. Shoreline accretion took place adjacent to the jetties, both north and south, filling the embayments formed between the jetties and the prejetty shoreline. The amount of accretion depended on the size of the embayment created. Sand for this accretion was supplied by beach erosion at greater distances from the jetties. In the case of the jetties at Tillamook Bay, the erosion was sufficiently severe to breach Bayocean Spit. A computer model is developed to simulate shoreline changes that occurred following construction of the Siuslaw River jetties. The model demonstrates deposition next to the jetty and erosion at greater distances, showing good agreement with the actual shoreline changes.

Growth Indices of the Clam Mya Arenaria

Newcombe and Kessler (1936) have presented a study of the growth indices of Mya arenaria L. as found in four widely separated localities on the Atlantic Coast. In the present study data from spring and fall collections from two localities on the shore of San Juan Island in the State of Washington are presented and compared with each other and with the findings of Newcombe and Kessler, which are re-examined. Although it was possible to make only a single small collection from the estuarine mouth of the Siuslaw River in Oregon, the data obtained there are included because of the extremely favorable conditions for the growth of the clam in that locality (Edmondson 1922). The present stock of Mya arenaria in the inland marine waters of the State of Washington and of British Columbia is generally considered to be descended from Atlantic stock accidentally introduced into Pacific waters not more than 80 years ago (Keep and Baily 1935: 117118). There are, however, indications (Newcomb 1875; Newcombe 1893; Oldroyd 1924) that Mya arenaria may be native in the Puget Sound-Strait of Georgia region. Hence, any differences found between clams of this area and those of the Altantic cannot unquestionably be referred to environment alone. For aid to the furtherance of this investigation the following are acknowledged: Curtis L. Newcombe of the U. S. Public Health Service and Oscar W. Richards of the American Optical Company for suggestions concerning the work; a number of citizens of San Juan Island for permission to collect clams from their tide lands; and the State of Washington funds for medical and biological research for financial aid. METHODS