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The early to middle Eocene submarine basalts of the Crescent Formation form the core and basement of the structurally uplifted Willapa Hills region of southwest Washington. The formation consists of a ...
Citation Citation
- Title:
- Geology of the middle and upper Eocene McIntosh Formation and adjacent volcanic and sedimentary rock units, Willapa Hills, Pacific County, southwest Washington
- Author:
- Moothart, Steve Rene'
The early to middle Eocene submarine basalts of the Crescent Formation form the core and basement of the structurally uplifted Willapa Hills region of southwest Washington. The formation consists of a thick sequence of predominantly subalkaline, tholeiitic pillow basalts and breccias formed as oceanic crust and seamounts at a sea floor spreading ridge or pull apart basin along the rifting continental margin of North America. Radiometric (Ar⁴⁰ - Ar³⁹) dating of the pillow basalt indicates an age of approximately 53 - 55 Ma for the formation. Foraminifera collected from mudstones interbedded with the pillow basalts of the Crescent Formation in southwestern Pacific County indicate a Ulatisian to lower Narizian (middle Eocene) age for the basalts and suggest that they were erupted in lower-middle bathyal (1500 - 2000 m) water depths. Locally associated with the pillow basalts are hyaloclastic basalt breccias and basaltic sandstones. Overlying, and interbedded with the basalts of the Crescent Formation is the middle and upper Eocene McIntosh Formation, which is composed of three members (informal). Stratigraphically from the lowest, these members are: 1) Fork Creek member; 2) Lebam member, 3) McIntosh Volcanics member. The Fork Creek member consists of a thick sequence of normally graded, micaceous, coarse- to fine-grained, arkosic and lithic arkosic sandstones deposited by sand-rich, high concentration turbidity currents in the deep marine-marginal basin. The turbidites were fed by a fluvial system carrying granitic and metamorphic detritus derived from erosion of Mesozoic crystalline rocks of the Okanagan Uplift region of northeastern Washington and southeastern British Columbia, and possibly the Idaho Batholith. Lithologically equivalent, shallow-marine and fluvial-deltaic sandstones with quartz and chert pebbles include the middle Eocene Carbonado Formation of the Puget Group and the upper portion of the type McIntosh Formation to the east. Microprobe determination of composition of plagioclase microlites and phenocrysts in volcanic fragments in the sandstones indicate a proximal volcanic source such as a pre Western Cascade basaltic andesite (e.g. Northcraft Volcanics) or possibly Challis Volcanics further east. Paleocurrent measurements suggest that dispersal of the turbidity flows to the west southwest within the basin was controlled by the active volcanic highs of the Crescent Formation. Lithofacies and foraminifers suggest that the Fork Creek member represents a small lowstand fan deposited during a fall in relative sea level either due to eustatic sea-level drop and/or tectonic uplift of the basin. Numerous dikes and sill-like bodies of porphyritic basalt to gabbro intrude both the pillow basalts of the Crescent Formation and micaceous arkosic sandstones of the Fork Creek member. These intrusions are generally concentrated near the contact between the two units and some appear to be fault controlled. Based upon major and trace element compositions,the intrusions can be separated into two types. The first type consists of subalkaline tholeiitic basalts and gabbros chemically equivalent to the oceanic basalt of the Crescent Formation. Radiometric dating of one of these sills which intrudes the upper portion of the Fork Creek member of the McIntosh formation is 48.7 + 0.5 Ma. These intrusions likely represent late stage events associated with waning activity of the Crescent basalts. The second group of intrusive rocks consists of high TiO₂ alkaline basalts similar in composition to the nearby subaerial basalt and basaltic andesite flows of the middle (?) to upper Eocene Grays River Volcanics. Radiometric dating of a trachybasalt dike from this group indicate an age of 41.4 + 0.7 Ma. Magnetic polarity measurements indicate that most middle Eocene basalts of the Crescent Formation formed at a time of normal magnetic polarity. Later intrusive equivalents of the Crescent Formation and the Grays River Volcanics typically show reversed magnetic polarities. An abrupt transgressive event due to eustatic sea level rise and/ or tectonic subsidence within the basin is recognized by the deposition of the thick sequence of deeper marine mudstones, siltstones, and minor distal, thin bedded, micaceous arkosic turbidites of the middle to upper Eocene Lebam member of the McIntosh Formation. This transgression is accompanied by a landward shift in the supply of arkosic sand-rich sediments and a hiatus of deposition of arkosic sand in this portion of the basin. The sea level transgression may be due to thermal subsidence of the basin at the cessation of Crescent volcanism. Massive to weakly bedded basaltic tuff and tuff breccia of the McIntosh Volcanics member is locally interbedded with the deep-marine strata in the upper portion of the Lebam member. This basaltic aquagene tuff may be associated with similar tuffs within the Grays River Volcanics elsewhere. Fine-grained, glauconitic sandstones of the basal portion of the latest Eocene to Oligocene Lincoln Creek Formation conformably overlie deep-marine strata of the Lebam member. The sandstone is generally massive, bioturbated, and contains gastropods and articulated pelecypod fossils These sandstones were deposited during a time of low sedimentation rates and represent progradation of shallow-marine sands during a period of highstand in relative sea level. Thin section and quantitative analyses by permeameter of the fine- to medium-grained arkosic sandstones of the Fork Creek member indicate relatively good porosity. However, the formation of authigenic pore-lining nontronite (smectitic) and/or chlorite clay rim cement, zeolites, and sparry calcite during diagenesis has significantly reduced permeability making these well-indurated turbidite strata of marginal reservoir quality. However, diagenetic effects such as dissolution of lithic framework grains and feldspar is observed and may enhance the porosity and permeability of the sandstones in the subsurface and subsequently improve the reservoir quality locally. Hydrocarbon source rock potential of mudstones within the Fork Creek and Lebam members indicate that these strata are generally organically lean and gas-prone (type III kerogen) with little or no potential for formation of liquid hydrocarbons. Mudstones are typically thermally immature (e.g. Ro < .494%), although, heating by proximal basaltic intrusions in the area is observed to result in local thermal maturation of some sedimentary strata into the oil window and beyond. Northwest-trending, high-angle, right lateral, oblique-slip faults are the dominant structural feature in the area. A subordinate set of northeast-trending faults appears to be truncated by the northwest-trending faults, and could represent an earlier episode of faulting or could possibly be en echelon and conjugate structures. The structural pattern is similar to that mapped in the Mist gas field of northwest Oregon. Northwest-trending faults commonly juxtapose arkosic sandstones of the Fork Creek member against volcanics of the Crescent Formation and large intrusive units or against the siltstone- and mudstone-rich overlying Lebam member. These faults could form structural traps for hydrocarbons if present in the subsurface to the north and east. Other possible traps include stratigraphic pinch outs and channeling of the arkosic sand-rich turbidites of the Fork Creek member within deep marine mudstones or onlap of these reservoir sands against volcanic highs within the basin. The thick fine-grained strata of the overlying Lebam member and the glauconitic sandstone of the Lincoln Creek Formation could act as a seal for the "reservoir sandstones" of the Fork Creek member.
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Because many coral-reef fishes are observable in situ, are amenable to transplantation, have small home ranges and short generation times, they provide a excellent system to investigate many topics within ...
Citation Citation
- Title:
- Coral-reef fishes : insights into larval dispersal and invasion ecology
- Author:
- Pusack, Timothy J.
Because many coral-reef fishes are observable in situ, are amenable to transplantation, have small home ranges and short generation times, they provide a excellent system to investigate many topics within general ecology, fisheries biology, and conservation biology. The primary goal of this dissertation was to use the coral-reef fishes system to investigate two pressing sets of issues that face marine ecologists and managers of living marine resources. The first topic is the spatial and temporal patterns of larval dispersal and reproductive success in a marine metapopulation (Chapter 2). Because miniscule larvae are difficult to track in the vast pelagic environment, little is known about the patterns of larval dispersal. Yet, the more that is understood about the spatial and temporal variability in larval dispersal, the easier it will be to identify sites that are self-sustaining and exporting larvae to unprotect sites, a common goal of marine reserves. Incorporating this information into siting of marine reserves will improve their effectiveness. The second topic is fundamental in the ecology of biological invasions: species specific interactions between an invasive predator and native species. Specifically, I investigated the ability of an invasive predator to disrupt natural population regulation of a native prey species (Chapter 3), and the ability of a native predator to provide biotic resistance against the invasive species (Chapter 4). Because management of the lionfish invasion is needed throughout the Caribbean and Atlantic waters, it is necessary to understand not only how lionfish can change the native system, but also potential ways to moderate the negative effects. To address the first topic, we collected a total of 3,278 genetic tissue samples from bicolor damselfish (Stegastes partitus) over a four year period from reefs near four islands that encompass Exuma Sound, Bahamas (Chapter 2). Using a Bayesian parentage analysis, eight parent-offspring pairs were detected, which directly documented both connectivity between and self-recruitment on an ecological time scale. Remarkably, some larvae returned to the exact same reef where they were spawned, while others traveled to sites greater than 100 km distance. The only study island without a detected parent-offspring pair, Lee Stocking Island, was also the island that showed the most restrictive gene flow on evolutionary time scales. Additionally, variability was documented in the spatial and temporal signatures of sweepstakes reproduction and Wahlund effects. The variation we observed may be influenced by seasonal mesoscale gyres present in Exuma Sound, which play a prominent role in shaping local oceanographic patterns. Understanding how to identify pathways of larval dispersal is important to designing networks of marine reserves, because a common goal of reserves is to protect populations that are self-seeding and can export larvae. Thus, this research not only demonstrates that temporal variability is a prominent characteristic of larval dispersal, but provides an example of how to identify these populations. To address the second topic, two studies using both lab observations and manipulative field experiments were conducted to study the interaction between invasive Indo-Pacific red lionfish (Pterois volitans) and two different native species. In the first study (Chapter 3) three different data sets were used to document the effect of lionfish predation on their top prey species, the bridled goby (Coryphopterus glaucofraenum). The first data set was extracted from three previous studies to compare the change in abundance of bridled goby between patch reefs with lionfish and patch reefs that were predator-free. The second data set came from laboratory feeding trials to test for the presence of a size refuge for bridled goby caused by lionfish gape limitation. The third data set came from a manipulative field experiment using 22 nearshore reefs where the per capita mortality of bridled gobies was compared among four orthogonal predator treatments: (1) predator-free control, (2) a single native predator only -- the graysby grouper (Cephalopholis cruentatus) -- representing the pre-invasion system, (3) a single lionfish only, and (4) one native grouper and one lionfish, representing the invaded system. The combined results from these three data sets demonstrated that lionfish can consistently consume a significant amount and an extremely high proportion of bridled goby on small patch reefs. While small lionfish cannot eat bridled goby larger than 0.42 times their body size, large lionfish eat virtually the entire size range of bridled goby. These findings indicate that lionfish have the potential to extirpate local goby populations. In the second experiment, lionfish were exposed to different abundances of a native grouper, the Nassau grouper (Epinephelus striatus), on 28 nearshore patch reefs in the Bahamas. Lionfish persistence and growth was monitored over 10 weeks, as well as the abundance of small, < 5 cm total length (TL), native reef fishes. Nassau grouper did not affect lionfish persistence or growth. Yet, reefs with a lionfish and many Nassau grouper saw a significant increase in the abundance of small reef fishes compared to reefs with only lionfish or lionfish with few grouper. Thus, it appears that high densities of Nassau grouper provide some biotic resistance on Bahamian patch reefs by potentially interfering with lionfish predation on native fishes, perhaps by interrupting stalking behavior. This dissertation highlights the flexibility of the coral-reef fishes system for investigation of broadly different topics in basic and applied ecology. Coral-reef fishes are a tractable system for both large and small scale studies, as well as laboratory observations and manipulative field experiments. The findings of this dissertation advance the understanding of metapopulation dynamics and have implications for fisheries management and marine reserve design. This research also documents further evidence of the negative effects of lionfish, yet provides some promising findings that may indicate some native biotic resistance to this devastating of marine invasions.
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Wheat is a globally traded staple crop. Wheat is important in human diets because of its agronomic adaptability, physical characteristics, functionality for the production of leavened products and nutritional ...
Citation Citation
- Title:
- Influence of Soft Wheat Characteristics on Quality of Batter-based Products
- Author:
- Fajardo Centeno, Carlos A.
Wheat is a globally traded staple crop. Wheat is important in human diets because of its agronomic adaptability, physical characteristics, functionality for the production of leavened products and nutritional value. Two significant characteristics make wheat an important staple food-crop. First, the proteins present in wheat endosperm have attributes that enable gas retention after the proteins are hydrated and mechanically worked during dough production. Second, a wider variety of products can be made out of wheat compared to other cereals. Wheat quality is defined in terms of suitability for specific end-uses. This is important for breeders, farmers, flour millers, and food producers and consumers. In the U.S. Pacific Northwest (PNW) climatic conditions favor production of soft wheat. Three soft wheat types are planted in the PNW, soft white winter (SWW), soft white spring (SWS), and club (CLUB). Batter-based products are important applications for soft wheats and include a wide range of products such as pancakes and waffles, cakes, and coatings. Pancakes are produced from fluid batters using a single step mixing process and contain sugar concentrations < 30% in their formulations. Cakes are complex food systems where their classification is based on mixing process to produce the batters and the sugar-flour ratio concentrations in their formulations. This dissertation is focused on the functionality, analysis, and selection of soft wheat quality traits that affect end-product performance and also developing a methodology to rapidly predict cake quality. The first study (Chapter 3) was concerned with the functionality of SWW wheats in pancake making. The aim of this study was to observe the differences in genotype and protein concentration on batter flow and pancake making performance of a collection of SWW wheats. Two formulations were used in the study: one based on Finnie et al (2006) called "old" and another based on the AACC-I Approved Method 10-80.01 called "new". The "new" lean formulation had an improved ability to distinguish the performance of different flours compared with the “old” as a result of wider range of pancake diameters. This study showed that pancake making performance would not be optimized by conventional superior high-quality soft wheat flours with soft kernel texture, high break flour yield, and low water-, carbonate-, and sucrose SRCs. From our results it appears that for unchlorinated flours, at least for thicker pancakes, the most appropriate flour would have higher water and sucrose SRCs and be grown under management conditions conductive to higher protein. The second study (Chapter 4) was a meta-analysis of data collected by the USDA Western Wheat Quality Laboratory (Pullman, WA). This study was done to advance understanding soft wheat quality traits that differentially affect sugar-snap cookie diameter (CODI) and Japanese sponge cake (SC) volume (CAVOL). Principal component analysis (PCA) and partial least square (PLS) regression models were used to obtain useful actionable information from the data. The overall data showed that break flour yield (BKFY) was the single most important trait positively associated with both CAVOL and CODI. SWW wheats showed CVs > 10% for kernel hardness (SKHRD), grain and flour protein concentrations, ash, sucrose-, and lactic acid SRCs. These observations suggested that hardness, protein, ash, and the two SRCs were more sensitive to G&E effects than were the end-product traits that had CVs < 10%. The third study (Chapter 5) was built on the second study by adding two additional quality tests, oxidative gelation capacity (PeakOXI) and median particle size, to the potential prediction of CODI and CAVOL. Similar to the second study, BKFY was the single most important trait positively associated with both CAVOL and CODI. Virtual selection of SWWs based on either BKFY or SKHRD alone showed (in both the second and third studies) that using these enabled a gain of 134 mL for CAVOL and 0.6 cm for CODI using SKHRD and 122 mL for CAVOL and 0.58 cm for CODI using BKFY (Chapter 5). PeakOXI was significantly correlated with CODI but not with CAVOL. This contrasted with our hypothesis that PeakOXI would affect both products similarly. Notably 13 SWW samples had PeakOXI values higher than 800 cP. PeakOXI values this high have never been observed in soft wheats prior to this study. This is a valuable genetic resource for further studies that may lead to ways to better exploit oxidative gelation. The fourth study (Chapter 6) expanded the concepts in previous studies and included the use of a test to measure cake-batter viscosity in an attempt to predict cake quality. This study investigated the relationships between wheat quality traits, cake batters, and cake making quality in three cake types: SC, layer cake (LC), and pound cake (PoC). This study differed from the studies in Chapters 4 and 5 and was similar to Chapter 3 as the samples were fewer but specifically chosen to span the entire range of typical SWW quality. In this study we also developed a viscosity-based method to predict SC and LC quality that takes only eight minutes. This could be useful for screening or selection for cake quality in soft wheat breeding programs. In SC, there were no significant differences in cake quality traits between varieties. However, SC volume had a strong negative association with PeakOXI. For LC, the variety Tubbs, with harder kernel and higher absorption characteristics, had the largest LC volume. In contrast to SC, LC volume was significantly and positively associated with PeakOXI. In PoC, Kaseburg, with the highest protein content, had the largest cake volume. PoC was significantly and positively associated with flour protein concentration suggesting that flour proteins were important for larger volumes and confirming other observations in the literature. In contrast to LC and SC, PoC was not significantly associated with PeakOXI. The overall impact of the studies reported is: - For pancakes, the most important soft wheat trait is flour protein concentration. Water-, and sucrose SRCs were potentially useful parameters for predicting pancake quality. - For SC and sugar-snap cookies, break flour yield was the most important single trait in predicting higher SC volumes and larger cookie diameters. Therefore, selection in soft wheat breeding should be focused on kernel hardness and break flour yields as primary factors.
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1384. [Article] Linking Habitat and Benthic Invertebrate Species Distributions in Areas of Potential Renewable Energy Development
While the coastal waters of western North America hold great promise for wind and wave energy development, many concerns have been raised about the potential environmental impacts of the installation of ...Citation Citation
- Title:
- Linking Habitat and Benthic Invertebrate Species Distributions in Areas of Potential Renewable Energy Development
- Author:
- Henkel, Sarah K., Goldfinger, Chris
While the coastal waters of western North America hold great promise for wind and wave energy development, many concerns have been raised about the potential environmental impacts of the installation of these devices and their complex mooring systems. Here I focus on characterizing benthic habitats and biological communities in offshore sedimentary and reef habitats where wind and wave energy facilities could be located. While little is known about species-habitat relationships and community processes in the depths and substrate types targeted for offshore renewable energy installation, an understanding of the natural dynamics of these systems is of utmost importance if we hope to forecast changes that might be brought about by wind and wave development. Since May 2010 we have conducted surveys of benthic habitats from northern California to Washington using a variety of techniques, providing baseline data on habitats and species potentially affected by wind and wave development, identifying species-habitat relationships, and quantifying spatial and temporal trends in species abundances and distributions. The first step in identifying and evaluating benthic communities is sonar mapping to determine depth and substrate types. In summer 2010 and 2011 six new offshore sites were mapped by the Seafloor Mapping and Plate Tectonics Lab at OSU using high-resolution multi-beam sonar and acoustic backscatter. In addition to the backscatter, Shipek grabs were taken in soft-bottom areas to collect sediment samples, which were run through a laser particle size analyzer (LDPSA) to determine actual grain size. Mapping began at the federal jurisdiction line and extended 9 – 12 miles offshore. Oregon and California have undertaken extensive mapping of state waters, so many areas have been mapped inshore of these sites as well. In summer 2011 and 2012, we visited 8 sites (6 newly mapped sites, one previously mapped, and one unmapped site) to collect a total of 153 cores using a 0.1 m2 box-corer. A sub-sample of sediment was collected from the corer and analyzed using the LDPSA; the rest was sieved through 1 mm mesh and all infaunal organisms were counted and identified. At each box core sampling station, CTD casts were conducted to obtain physical data describing the overlying water column for further habitat characterization. Unique infaunal invertebrate assemblages were found in sedimentary habitats at each of the Pacific Northwest shelf sites. Thus for renewable energy siting, it does not appear that baseline surveys conducted at one site can necessarily serve as a proxy for distant sites. However, some general trends were detected. Significantly different invertebrate assemblages were found in different depth ranges with a break at approximately 80 to 90 m depth; deeper sites exhibited greater diversity. Shallower sites had greater spatial heterogeneity in infaunal invertebrate assemblages than deeper sites; thus as monitoring protocols are developed we recommend that shallower sites be sampled more extensively in order to adequately characterize those communities. Molluscs seemed to be the most responsive to substrate type, with different assemblages found in pure sand, slightly muddy sand, and mostly silt/clay. In addition to sampling of sedimentary habitat, we conducted limited surveys of offshore reef habitats. Although it is unlikely that devices would be installed in these areas, reefs may be crossed by electrical cables, and changes in sediment transport due to ocean energy extraction or alterations of flow around large device arrays could lead to community impacts. The aim of this study was to describe baseline relationships between macroinvertebrate communities and habitat features against which to measure potential future impacts and to develop tools to predict community compositions of unsampled areas in the region based on substrate features. To date we have analyzed submersible dive video from three sites conducted in the mid-1990s. In the summers of 2011 and 2012, we visited these previously surveyed sites with an ROV. Analysis of submersible and ROV surveys indicated that two major substratum groups held different macroinvertebrate assemblages: moderate to high-relief rocky habitats and low-relief fine sediment habitats. The majority of macroinvertebrate taxa were associated with high-relief rocks; these taxa were further differentiated between flat and ridge rock habitats. Low-relief fine sediment habitat was most often associated with motile invertebrates. Within this habitat it appeared that fine-sediment substrata mixed with mud, boulders, or gravel each yield unique macro-invertebrate associations versus those found on uniformly mud or sand substrata. Latitude also was correlated with variation in macroinvertebrate assemblages. A major challenge will be detecting effects of wind and wave energy installations above the inherent natural variability in these systems. Decadal scale shifts in the California Current affect this ecosystem, with warm regimes and associated declines in planktonic production resulting in degradation of benthic community. On shorter timescales El Niño events can cause major, short-term disturbances. Off the Oregon coast, summer hypoxia events can have dramatic effects on benthic communities, and ocean acidification is an increasing concern. Thus, evaluation of this ecosystem must be made in the context of seasonal and climatic trends. Prior to installation of device arrays, baseline sampling is usually required as part of the permitting process. However, one-time sampling will not capture the variability of the system in a given area, and developers and regulators typically are not able to make the investment (in time or money) to repeatedly survey an area before development. Funding agencies rarely support long-term monitoring studies. Thus, finding support for repeated field sampling across time and space is especially challenging. The biggest issue facing wind and wave energy developers in the environmental arena is the high level of uncertainty regarding environmental effects. Without a substantial understanding of the natural dynamics of a system, it will be difficult to reduce that uncertainty.
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1385. [Article] Tidal influence on downstream fining in gravel-bed rivers
This research examines the downstream fining phenomenon as it operates in coastal gravel-bed rivers of Oregon. Downstream fining is a change in bed composition toward smaller sediment sizes in the downstream ...Citation Citation
- Title:
- Tidal influence on downstream fining in gravel-bed rivers
- Author:
- Coles, Derron Rafiq
This research examines the downstream fining phenomenon as it operates in coastal gravel-bed rivers of Oregon. Downstream fining is a change in bed composition toward smaller sediment sizes in the downstream direction. Changes in stream flow discharge and channel slope affect the rate of bed-load transport, thereby altering the downstream fining regime. This research focuses on ascertaining the rate of downstream fining and the characterization of tidal influence on bed-load transport in the lower-river reaches. For this purpose, a combination of physical and numerical analysis techniques were used. Variations of particle size distributions and specific gravity values were assessed along the main channel. Numerical analysis techniques included a MATLAB program for simulating bed-load transport as affected by tide. The numerical model developed for this investigation, TIMM (Tidally Influenced Movement Model) uses physically based excess shear stress as the underlying mechanism. Namely, an undulating water surface is applied to Shields criterion for incipient motion and bed-load transport. The Generalized Stream Tube model for Alluvial River Simulation version 2.1 (GSTARS 2.1), developed by the Bureau of Reclamation, was used to validate conclusions drawn from field data analyses. The five rivers of the Tillamook Basin were the sites of field data collection. The Tillamook Basin is located approximately 60 miles (96.6 kilometers) west of Portland, Oregon and 60 miles (96.6 kilometers) south of the Columbia River mouth at the Pacific Ocean. The basin has a total area of 570 square miles (1476 square kilometers) including Tillamook Bay, which is the second largest estuary in Oregon. All rivers empty into the Tillamook Bay. From north to south, the rivers are the Miami, Kilchis, Wilson, Trask and Tillamook. The Kilchis River was the primary field research site and the other four rivers allowed expansion of field research for added understanding of downstream fining. Bulk sampling of the armor and sub-armor layer of the Kilchis River was completed for five sidebars along the river, from river mile 0 to river mile 14 (0 - 22.5 km). Photo frame sampling was carried out for the armor layer of sidebars along the four additional rivers. In total, 21 sampling locations with 141 individual sampling points were used for the particle size analyses. Assessment of longitudinal variation in specific gravity of bed particles by size fraction was performed for all five rivers. Particle size analyses showed a distinct downstream fining trend. Kilchis River surface particle sizes decreased from 216 mm at river mile 14 (22.5 km) to 10 mm at river mile 0. Miami River surface particle sizes decreased from 43 mm at river mile 9 to 29 mm at river mile 1.5 (2.4 km). Wilson River surface particle sizes decreased from 51 mm at river mile 27 to 23 mm at river mile 0. Trask River surface particle sizes decreased from 55 mm at river mile 18 to 26 mm at river mile 4 (6.4 km). Diminution coefficients (rates of size reduction) were found to be 0.55 km⁻¹ for the armor layer and 0.48 km⁻¹ for the sub-armor layer of the Kilchis River. The R-squared values for the armor and sub-armor coefficients are 0.92 and 0.99, respectively. Results of regression analyses performed for the photo frame sampling data were 0.02, 0.03, and 0.04 km⁻¹ for the Miami, Wilson, and Trask Rivers, respectively. R-squared values of 0.19, 0.78, and 0.81, respectively. Diminution coefficients reported for all rivers were far outside the value reported for abrasion-dominated systems (0.089 km⁻¹), yet were within the range of diminution coefficients reported for selective sorting-dominated systems (0.001 to 0.05 km⁻¹). Average specific gravities for bed material were 2.78, 2.68, 2.73, 2.56, and 2.76 for the Miami, Kilchis, Wilson, Trask, and Tillamook Rivers, respectively. Simulations of sediment transport within the tidal portion of the Kilchis River (river mile 0 to 3 or 0 to 4.8 km) using TIMM at moderate river streamflow above the threshold for transport of material showed that tidal influence causes distinct deposition zones during periods of high, low, and moderate tide levels. Depositional zones were found to propagate downstream with increases in river discharge, such that at elevated river stage the location of depositional zones associated with tide levels were undistinguishable. It can be concluded that tide has a significant influence at flows below, and moderately above the threshold for transport. Simulations of a simplified version of the Kilchis River using GSTARS 2.1 produced comparable results to the TIMM simulations. GSTARS 2.1 was run using three scenarios, 1) a uniform bed and incoming sediment supply set at 7.9 mm, 2) a mixed bed with mean sediment diameter of 7.9 mm and coarser incoming sediment supply, and 3) a mixed bed with mean sediment diameter of 7.9 mm and finer incoming sediment supply. Each scenario had output data that show maximum deposition in the zone of tidal influence. The location of head of tide for the simplified Kilchis River was found to occur at river mile 5 instead of river mile 3 used for the head of tide in TIMM simulations. GSTARS 2.1 simulations showed that variations in particle size distribution of incoming sediment supply influence rates of downstream fining. An incoming sediment supply that had a coarser particle size distribution than the particle size distribution of the bed resulted in an observable increase in deposition of large particle sizes in the upstream reaches; however, there was no observable increase in deposition of large particle sizes in downstream reaches. An incoming sediment supply that had a finer particle size distribution than the particle size distribution of the bed resulted in an observable increase in deposition of smaller particles in the downstream reaches, with no observable increase in deposition of smaller sizes in the upstream reaches. Therefore, simulations show evidence that sediment supply of particles coarser than the bed causes increased rates of fining in reaches near the sediment source. Key contributions of this research are in the categories of methodology, numerical analysis, and basic understanding of the fate and transport of sediment in the zone of tidal influence. It has been shown that particle size data, collected in detail on sidebars, can be used in conjunction with specific gravity data to categorize in-stream particles based on probable origin and type. Characterization of sediment transport in the zone of tidal influence using numerical models showed the tide cycle influences the downstream fining trend in lower reaches by shifting the zone of deposition farther upstream than would the case without tidal influence, with a net effect of increasing the rate of downstream fining. Moreover, tidal influence was found to have an inverse relationship with water discharge. Finally, it was shown that numerical modeling of river reaches in the tidal zone should include consideration of tidal fluctuations in order to predict erosion and depositional areas more accurately.
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Methane (CH4) is one of the most important greenhouse gases after water vapor and carbon dioxide due to its high concentration and global warming potential 25 times than that of CO2 (based on a 100 year ...
Citation Citation
- Title:
- A 30-Year Record of the Isotopic Composition of Atmospheric Methane
- Author:
- Teama, Doaa Galal Mohammed
- Year:
- 2013
Methane (CH4) is one of the most important greenhouse gases after water vapor and carbon dioxide due to its high concentration and global warming potential 25 times than that of CO2 (based on a 100 year time horizon). Its atmospheric concentration has more than doubled from the preindustrial era due to anthropogenic activities such as rice cultivation, biomass burning, and fossil fuel production. However, the rate of increase of atmospheric CH4 (or the growth rate) slowed from 1980 until present. The main reason for this trend is a slowdown in the trend of CH4 sources. Measuring stable isotopes of atmospheric CH4 can constrain changes of CH4 sources. The main goal of this work is to interpret the CH4 trend from 1978-2010 in terms of its sources using measurements of CH4 mixing ratio and its isotopes. The current work presents the measurements and analysis of CH4 and its isotopes (δ13C and δD) of four air archive sample sets collected by the Oregon Graduate Institute (OGI). CH4 isotope ratios (δ13C and δD) were measured by a continuous flow isotope ratio mass spectrometer technique developed at PSU. The first set is for Cape Meares, Oregon which is the oldest and longest set and spans 1977-1999. The integrity of this sample set was evaluated by comparing between our measured CH4 mixing ratio values with those measured values by OGI and was found to be stable. Resulting CH4 seasonal cycle was evaluated from the Cape Meares data. The CH4 seasonal cycle shows a broad maximum during October-April and a minimum between July and August. The seasonal cycles of δ13C and δD have maximum values in May for δ13C and in July for δD and minimum values between September-October for δ13C and in October for δD. These results indicate a CH4 source that is more enriched January-May (e.g. biomass burning) and a source that is more depleted August-October (e.g. microbial). In addition to Cape Meares, air archive sets were analyzed from: South Pole (SPO), Samoa (SMO), Mauna Loa (MLO) 1992-1996. The presented δD measurements are unique measured values during these time periods at these stations. To obtain the long-term in isotopic CH4 from 1978-2010, other datasets of Northern Hemisphere mid-latitude sites are included with Cape Meares. These sites are Olympic Peninsula, Washington; Montaña de Oro, California; and Niwot Ridge, Colorado. The seasonal cycles of CH4 and its isotopes from the composite dataset have the same phase and amplitudes as the Cape Meares site. CH4 growth rate shows a decrease over time 1978-2010 with three main spikes in 1992, 1998, and 2003 consistent with the literature from the global trend. CH4 lifetime is estimated to 9.7 yrs. The δ13C trend in the composite data shows a slow increase from 1978-1987, a more rapid rate of change 1987-2005, and a gradual depletion during 2005-2010. The δD trend in the composite data shows a gradual increase during 1978-2001 and decrease from 2001-2005. From these results, the global CH4 emissions are estimated and show a leveling off sources 1982-2010 with two large peak anomalies in 1998 and 2003. The global average δ13C and δD of CH4 sources are estimated from measured values. The results of these calculations indicate that there is more than one source which controls the decrease in the global CH4 trend. From 1982-2001, δ13C and δD of CH4 sources becomes more depleted due to a decrease in fossil and/or biomass burning sources relative to microbial sources. From 2005-2010, δ13C of CH4 sources returns to its 1981 value. There are two significant peaks in δ13C and δD of CH4 sources in 1998 and 2003 due to the wildfire emissions in boreal areas and in Europe.
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1387. [Article] Variation in the timing of coho salmon (Oncorhynchus kisutch) migration and spawning relative to river discharge and temperature
Coho salmon (Oncorhynchus kisutch) migration and spawning are unique components of the salmon life cycle because they require synchrony of behavior with other individuals as well as with acceptable fluvial ...Citation Citation
- Title:
- Variation in the timing of coho salmon (Oncorhynchus kisutch) migration and spawning relative to river discharge and temperature
- Author:
- LovellFord, Rachel
Coho salmon (Oncorhynchus kisutch) migration and spawning are unique components of the salmon life cycle because they require synchrony of behavior with other individuals as well as with acceptable fluvial conditions. As with other organisms that exhibit group mating behavior, it is likely that environmental cues trigger coho salmon movement to spawning grounds. These cues may also provide usable habitat for migration and spawning. River discharge, temperature, and length of day have long been assumed to be the environmental cues which trigger migration and spawning of coho salmon as coho return within the same season each year to spawn. Hatchery studies have also shown that the timing of reproductive behavior is heritable. If this heritability is determined by the fluvial conditions of the spawning grounds, then a predictable relationship should exist between reproductive behavior and the hydrologic and thermal regimes. Surprisingly, no defensible correlations between discharge thresholds and spawning or migrating activity have been identified for naturally reproducing coho salmon. Thermal, velocity, and depth limitations have been identified for coho salmon, but these values have not been examined in combination or within the context of a hydrologic and thermal regime. This study compares interannual patterns in the timing of coho mid-river migration in the North Umqua (180 km up river from the estuary) and the initiation of spawn timing in the Smith River basins (Oregon) with river discharge and water temperature data to ascertain whether these behaviors are driven by fluvial conditions. Additionally, we used this data to identify the window over which most migration and spawning takes place in our test systems. On the North Umpqua, coho salmon mid-river migration initiated (first 5% of migrants) after summer peak temperatures and following a threshold average daily temperature of 18 C°, but before fall storm events occurred. In most years, approximately 75% of the migrating coho salmon have moved past the Winchester Dam before fall storms initiated and when discharge remained less than the 11 year average for the month of November, more similar to summer than winter flow levels. Additionally, characteristic lengths and numbers of peaks within the distribution of annual migrations were attributable to the generational cohort that the migration belonged to despite the similarity in population size across all years. These patterns in the distribution of generational cohorts suggest an inherited timing response as well as highlight cohorts which may contain diminished sub-populations. The initiation of coho salmon spawning appears limited both by a thermal threshold of 12 C° in all basins, as well as by a minimal discharge threshold, which is unique to each stream. Continued spawning activity occurs as discharge remains elevated from fall levels. It is also notable that there was no statistical difference in the date of the initiation of spawning within each basin in a given year or across years at a given site. Together, these studies highlight the important role that the coho salmon genome plays in reproductive timing as well as the ways that fluvial thresholds limit reproductive behavior in time. Coho have survived because of their genome has been resilient when faced with environmental change. Future work should consider variability in fluvial conditions relative to coho salmon phenotypic plasticity over time. Coho salmon phenotypic plasticity will determine whether the rate of change of the hydrologic and thermal regimes important to coho salmon survival outpaces the coho’s ability to adapt. This study contributed to this future work by establishing baseline relationships between the behavior of a threatened species and measurable environmental thresholds.
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1388. [Article] Petrology and geochemistry of the Emigrant Pass volcanics, Nevada : implications for a magmatic-hydrothermal origin of the Carlin gold deposits
The Emigrant Pass volcanics (EPV) are a 38.3 to 36.4 Ma calc-alkaline volcanic center that erupted andesite and dacite, and a late series of felsic dikes along the south flank of the Carlin gold district ...Citation Citation
- Title:
- Petrology and geochemistry of the Emigrant Pass volcanics, Nevada : implications for a magmatic-hydrothermal origin of the Carlin gold deposits
- Author:
- Johnson, Curtis L. (Curtis Lawrence)
The Emigrant Pass volcanics (EPV) are a 38.3 to 36.4 Ma calc-alkaline volcanic center that erupted andesite and dacite, and a late series of felsic dikes along the south flank of the Carlin gold district in north-central Nevada. The EPV includes dacite and rhyolite porphyry dikes indistinguishable from porphyry dikes associated with mineralization within the district. The volcanic rocks likely represent eruptive equivalents of deeper, unexposed Eocene plutons that may be the source of heat, fluids, and metals of Carlin-type gold deposits. New petrologic and geochemical data of the EPV are presented to test this hypothesis. The EPV are exposed over a 30 x 15 km area, have an estimated volume of 100 to >200 km³ and are divided into the early Primeaux lavas (38.1-38.3 Ma), the Mack Creek lavas and related intrusions (37.1-38.4 Ma), and late eruptive and hypabyssal rocks (Henry and Faulds, 1999). The Primeaux lavas are a >500 m thick sequence of pyroxene and hornblende andesite to dacite lavas and intrusions; minor pyroxene, hornblende and biotite dikes; and volcanic conglomerates. The Mack Creek lavas are a 180 m thick succession of porphyritic dacite lava flows, domes, and intrusions. Late small-volume units include the Bob Creek basaltic andesite to andesite lava (37.7 Ma) and rhyolitic to dacitic dikes (36.4-36.7 Ma). Primeaux andesite crystallized early clinopyroxene, orthopyroxene, plagioclase, and late hornblende, which suggests moderate water contents (~3 wt.%). Mack Creek dacite and late rhyolite-dacite dikes crystallized hornblende and biotite early, attesting to high water contents (>4 wt.%). Early Primeaux andesites contain abundant magnetite and sparse ilmenite, whereas Mack Creek dacites and late rhyolite-dacite dikes contain magnetite and local titanite. This mineralogy is consistent with the evolution of magmas from early moderately oxidized conditions to late strongly oxidized conditions (fO2 ≥ NNO+2) similar to porphyry copper magmas (Dilles, 1987). Carlin plagioclase-biotite-hornblende dacite porphyry dikes associated with gold ores yielded four new LA-ICP-MS U/Pb zircon ages (36.7±1.8, 38.8±1.7, 39.2±1.6, 39.4±1.5 Ma), overlapping in age with the earliest EPV eruptions. Two additional U/Pb zircon ages were obtained on a coarsely porphyritic dacite lava of the Mack Creek sequence (37.10±0.54 Ma), and a porphyritic dacite lava (148.2±2.3 Ma) likely of the Frenchie Creek Volcanics at the southern terminus of the EPV. All analyzed Carlin porphyries contain zircons with EuN/EuN* versus Hf arrays and EuN/EuN* > 0.4 similar to porphyry copper plutons (Dilles et al., 2015) and the 36 Ma Battle Mountain granodiorite porphyry associated with Cu(Au) ores (Farmer, 2013). Abundant partially melted granite xenoliths in EPV rocks indicate assimilation of crust during magma generation, whereas incompletely mixed magmas with differing mineralogy along with abundantly sieved plagioclase and resorbed amphibole indicate magma mixing processes. The andesites and dacites have high-K to shoshonitic compositions similar to subduction-related arc magmas. Whereas most major elements display simple linear correlations with silica, interpreted to indicate mixing, the MgO and Cr of most samples abruptly decrease with increased silica consistent with crystal fractionation. Dacites of the Mack Creek have elevated MgO and Cr compared to Primeaux andesites and Bob Creek basaltic-andesites, consistent with mixing of primitive basaltic andesite or andesite with rhyolite. Enrichment in Rb, Ba, and Cs indicate crustal additions compared to average arc magmas, whereas elevated V/Sc (1.4-17.3; Mean: 8.9) and Sr/Y (16.6-49.6; Mean: 36.1) ratios are similar to mineralizing porphyry Cu (Au) magmas (Loucks, 2014). Hornblende compositions from four samples are bimodal and include both low-Al and high-Al amphiboles now commonly recognized in arc suites (Aucanquilcha, Chile: Walker et al., 2013; Yanacocha, Peru: Chambefort et al., 2013). Using the Ridolfi et al. (2010) formulation, the low-Al hornblende crystallized at 820-890°C and 100-250 MPa (4-10 km depth), whereas high-Al amphibole crystallized at about 900-980°C and possibly greater depths. Electron microprobe studies of magmatic sulfide inclusions indicate monosulfide solid solution (MSS, pyrrhotite at low temperatures) was the dominant magmatic sulfide species with minor (n=4 of 119 analyses) intermediate solid solution (ISS, chalcopyrite at low temperatures). Sulfide contents decrease systematically as the magmas evolved from andesite-dacite-rhyolite, supporting the observation of increasing oxidation state and magmatic sulfate/sulfide ratio. Additionally, all phases of the EPV are highly depleted in whole rock Cu (<10ppm), suggesting Cu was efficiently removed during volatile exsolution at depth or alternatively was sequestered in magmatic sulfide at depth. Experimental studies of Au partitioning in intermediate composition melts indicate that the predominance of MSS over sulfide liquid or ISS is a prerequisite for forming Au-rich melts as MSS preferentially incorporates Cu over Au, thereby further enriching the Au/Cu ratio of the remaining melt (Muntean et al., 2011; Botcharnikov et al., 2013; Yi and Audetat, 2013). Muntean and others (2011) proposed a magmatic-hydrothermal fluid and metal source of the Carlin gold deposits and suggested source magmas were fundamentally enriched in Au relative to Cu as a result of MSS fractionation over ISS or sulfide liquid, which is supported by these new data on EPV magmatic sulfide inclusions.
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1389. [Article] Population Structure of Island-Associated Pantropical Spotted Dolphins (Stenella attenuata) in Hawaiian Waters
Understanding gene flow, diversity, and dispersal patterns is important for predicting effects of natural events and anthropogenic activities on dolphin populations. With the very recent exceptions of ...Citation Citation
- Title:
- Population Structure of Island-Associated Pantropical Spotted Dolphins (Stenella attenuata) in Hawaiian Waters
- Author:
- Courbis, Sarah Shelby
- Year:
- 2011
Understanding gene flow, diversity, and dispersal patterns is important for predicting effects of natural events and anthropogenic activities on dolphin populations. With the very recent exceptions of false killer whales (Pseudorca crassidens), spinner dolphins (Stenella longirostris), and common bottlenose dolphins (Tursiops truncatus), Hawaiian odontocete species are managed as single stocks within the U.S. Hawaiian Exclusive Economic Zone. These exceptions are a result of recent studies that have indicated that some species have populations that show fidelity to individual islands or groups of islands, resulting in genetic differentiation, often with management implications. The first part of my study (following the introductory chapter) focused on population structure of pantropical spotted dolphins (Stenella attenuata) near the Hawaiian Islands. Because of the level of human interaction, pantropical spotted dolphin populations need to be defined accurately to be managed in a way that will avoid local population losses, especially given that the commercial and recreational troll fisheries near the islands "fish on dolphins" to catch tuna. I analyzed genetic samples for mtDNA and microsatellite loci from four island regions: Hawai'i, the 4-islands area, O'ahu, and Kaua'i/Ni'ihau. My results support genetic differentiation among the regions of Hawai'i, the 4-islands area, and O'ahu and suggest that pantropical spotted dolphins near Kaua'i/Ni'ihau are likely transient and in very low numbers. There was no strong evidence to support sex-biased dispersal or group fidelity. Possibly, differentiation is mediated by behavior adapted to differing habitat types. From a management perspective, spinner and bottlenose dolphin populations near the Hawaiian Islands have been split into separate stocks for management based on levels of genetic differentiation similar to those found for pantropical spotted dolphins. These precedents suggest that comparable action should be taken to split pantropical spotted dolphin stocks near the Hawaiian Islands. Most population studies rely heavily upon fixation indicies like FST to determine whether populations are genetically differentiated. When FST values are low but significantly different from zero, it can be difficult to interpret the biological significance of these values. As part of my study, I suggest that one way to evaluate whether small FST values indicate significant differentiation is to compare FST values with other populations considered to be separate based on factors such as extreme distance or morphological differences. I examined pantropical spotted dolphins from the coastal and offshore Eastern Tropical Pacificm (ETP), Hawaiian Islands, and China/Taiwan to examine the utility of comparing FST values across separate populations. Among Hawaiian Island regions, FST values are significantly different from zero but small. The comparison of these FST values with more distant populations in the ETP and China/Taiwan indicated that differences among Hawaiian Island regions were similar in magnitude to those found between the offshore and coastal ETP sub-species, but smaller than between the Hawaiian Island regions and the other regions examined. This suggests a level of reproductive isolation among the Hawaiian Islands regions that is comparable to that of offshore and coastal ETP populations, and supports the value of fixation index comparisons in evaluating differentiation among putative populations. My results suggest that assigning specific numerical baseline FST values may not always be biologically meaningful but that determining whether related populations with geographic or other separation show a preponderance of similar, lower, or higher fixation index values can help evaluate whether genetic differences among sympatric or parapatric groups warrants designating them as separate populations for management. Lastly, I explore whether the fast evolving mtDNA control region may be more suited to phylogenetic comparisons among the Stenella than slower evolving gene regions and whether the small number of haplotypes generally used in phylogenetic analyses is adequate for defining relationships among dolphins. Usually, slow evolving regions, such as gene regions, are used in phylogenetic analyses because species and genera have been isolated long enough for variation to have accumulated in such regions but not so long that many reversals (i.e. a mutational change in sequence that later changes back to the original sequence) have occured. The mtDNA control region is typically used for population genetic comparisons rather than phylogenetic comparisons because it is considered to be a fast evolving region. Historically, dolphin phylogeny has been examined using gene regions, which have resulted in ambiguous and unexpected relationships. However, the lack of variation in the mtDNA control region for pantropical spotted dolphin populations and the fact that recent studies have found that the mtDNA control region in cetaceans evolves at about one quarter the rate of other mammals, raises the question as to whether this region would be better suited to phylogenetic studies for the Stenella (and potentially other dolphin species). In comparing 346 haplotypes from five species of Stenella world-wide, I found that the mtDNA control region is probably not a good region to use for phylogenetic analyses, and that even faster evolving regions might perform better. The differences in the mtDNA control region were not sufficient to distinguish clear relationships among the Stenella. I also found that when subsets of haplotypes chosen at random were compared, the results differed among comparisons, suggesting that there is value in using more than the usual one or two haplotypes when making phylogentic comparisons. Given the recent increases in sequence availability (e.g. GenBank) and computing power, researchers should strongly consider using many haplotypes from a variety of populations in their phylogenetic comparisons.
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1390. [Article] Physical-Environmental Effects of Wave and Offshore Wind Energy Extraction: A Synthesis of Recent Oceanographic Research
The ocean deployment of arrays of Wave Energy Converters (WEC arrays) appears likely in the near future, and deployment of offshore wind turbines has already started. These technologies tap into a potential ...Citation Citation
- Title:
- Physical-Environmental Effects of Wave and Offshore Wind Energy Extraction: A Synthesis of Recent Oceanographic Research
- Author:
- Özkan-Haller, Tuba, Haller, Merrick C.
The ocean deployment of arrays of Wave Energy Converters (WEC arrays) appears likely in the near future, and deployment of offshore wind turbines has already started. These technologies tap into a potential renewable energy resource but also involve complex systems with uncertain environmental consequences that will likely scale with the size of their ocean footprint. This synthesis talk will concentrate on the potential physical effects of these array technologies. Both WEC arrays and offshore wind farms consist of sizable structures placed in the water column; hence, their mere presence is a potential environmental stressor. Possible effects on the physical environment include wave scattering and wave shadowing; added drag on the coastal current field; modifications to sediment transport (by way of the aforementioned changes to the wave and current forcing); and changes to local sediment characteristics (due to anchors and pilings). In many ways, these effects are similar to those caused by other ocean structures that have been studied for some time (e.g., offshore platforms). However, there are additional potential effects of WECs and wind turbines that require further attention. For example, extraction of wave energy by WECs could have additional environmental consequences. Similarly, offshore wind farms can alter the local wind field, in turn altering locally-generated waves. We will address effects due to wave or wind installations on the wave field, on local ocean circulation, and on sediment transport characteristics. Because WECs partially extract and scatter incident wave energy, they cause significant modifications in the near-field. In fact, if device performance can be optimized at field scales, then by definition the near-field effects will be maximized, i.e., if energy extraction is maximized the potential physical effects of WECs are also maximized. Over the past decade a sizable number of studies have applied theoretical principles using varying assumptions and simplifications to the problem of WEC-wave interactions. Some of these assumptions (e.g., “optimal” motions, monochromatic wave conditions, etc.) have now been shown to be unrealistic, and there has been a convergence toward classes of models that appear to produce reasonable estimates. While recent model studies have managed to bound the problem, significant uncertainties remain. The primary cause for the remaining uncertainties is the lack of observational studies, particularly data sets that provide spatial information about the wave field in the vicinity of in situ devices. Nonetheless, a few studies have undertaken scaled laboratory testing, and these data sets are beginning to lend confidence to the available numerical model results and shed light on the dominant processes. Once near-field effects are understood, far-field effects can be assessed. Far-field effects influence the wave field near beaches, which, in turn, influences the sand transport processes that govern the morphodynamics of the beach face. Fortunately, hydrodynamic modelling of large-scale wave propagation processes in the absence of structures is highly advanced, i.e., if given accurate incident wave conditions in the lee of an installation and bathymetry for the model domain, models can well-simulate local wave conditions, wave-driven currents and sediment transport patterns. Therefore, once near-field WEC/wave dynamics are understood, expanding our understanding to the far-field will be relatively straightforward. Nonetheless, observational studies of far-field beach modifications shoreward of an installation will help to further solidify our understanding of beach behaviour. Offshore wind farms can also potentially influence the local wind field around them. Previous studies of such modifications at land-based wind farm installations serve as a reasonable basis for predictions offshore . Any changes to offshore winds will also influence the local wave field, especially where local winds are the dominant source of waves. Such effects will be minimal near coasts where the local wave climate is dominated by incident swells generated at large distances (e.g., the U.S. West Coast). In contrast, locally generated waves are a more important component of the wave climate on the East Coast of the U.S Modification to ocean currents by an array of structures can be assessed by considering the additional frictional effects (“form” drag) caused of the array. If the drag caused by a dense of array of structures is large, circulation will be altered, which might result in reduced current velocities or the diversion of currents toward an area of less drag. Note that ocean currents already experience drag due to bottom friction; hence, the question hinges on the relative magnitude of the drag induced by structures versus the pre-existing frictional drag. Finally, any near-field modifications to the wave and circulation field (due to either WEC arrays or wind farms) will necessarily result in changes in sediment transport. Any local reduction in flow velocities can result in a reduction of the sediment carrying capacity of circulation leading to sediment accumulation at the site. Small-scale modification to a current will also likely cause bumps and holes around the pilings or anchors. These effects are similar to those observed around existing offshore structures and pilings, and can be accounted for in the design of the structures. Far-field modification of waves and associated changes in wave-induced currents can also result in changes in sediment transport patterns near beaches. Although some recent studies exist, questions regarding far-field effects on beaches are still relatively poorly addressed.