American West Coast Research Articles

Decadal variation of temperature inversions along Line P

Hydrographic data measured for 50 years along Line P between the North American west coast and mid Gulf of Alaska as well as data from profiling float observations were analyzed to study the formation and variation of temperature inversions in the eastern subarctic North Pacific. Remarkable decadal to inter-decadal variation was observed in the magnitude of temperature inversions. This variation was mostly attributed to the variation of southward Ekman transport, eastward geostrophic transport, and surface cooling.

Toward Transpacific Ecopoetics: Three Indigenous Texts

In this article, I employ "the Pacific" as a contact zone, method, and concept with which to examine the dynamic, shifting relationship between land and sea that allows indigenous literature in the transpacific context to engage all of its ecopoetic complexity. The Pacific is the largest oceanic divide on earth. In recent years, issues around global capitalism, national identity, community, and the ecology of the Pacific region have sparked intriguing and provoca- tive discussions. Research along these lines celebrates the networking and coalition activities of various groups of people in the Pacific, and highlights the circulation of ideas and cultures that I believe to be crucial to contem- porary ecological scholarship. It offers an oceanic perspective that serves as a counterweight to continental ways of thinking, and it supplements or challenges transnational approaches to imperialism, postcolonialism, indi- geneity, globalization, and ecology. 1 A recent special issue of the Contemporary Pacific titled "Native Pacific Cultural Studies on the Edge" examines uncharted spaces of the Pacific Islands and historicizes indigenous discourses about making landfall, showing how they have contested the production of new transoceanic environments. The articles in this special issue "explore notions of Pacific indigeneity as they circulate through geographical, cultural, political, and historical flows of people(s), things, knowledge, power—between islands and continents." 2 As the United States and China battle over this geographical space, the message from the indigenous Pacific can be inspiring: neighboring communities have always exchanged ideas and products, often across vast oceanic distances. It was a large world in which indigenous people intermingled along numerous interconnecting routes, unhindered by the boundaries erected much later by imperial powers. Indeed, the recent wave of research on transnational

Role of sediment denitrification in water column oxygen dynamics: comparison of the North American East and West Coasts

Abstract. Low oxygen concentrations, either natural or anthropogenically driven, can severely affect coastal marine ecosystems. A deeper understanding of oxygen dynamics is required in order to improve numerical models, eventually to predict the timing and severity of hypoxia. In this study we investigate the effect of sediment denitrification on oxygen concentrations in bottom waters over the continental shelf. We used two coupled physical-biological models based on the Regional Ocean Modelling System (ROMS) to compare summer simulations with and without denitrification within the sediments for two North American shelves: the Middle Atlantic Bight (MAB) and the Vancouver Island Shelf (VIS). These regions belong to western and eastern boundary current systems, respectively, and are characterized by different physical and biological dynamics. Both models assume coupled nitrification-denitrification within the sediments. Denitrification represents a loss of bioavailable nitrogen through the production of dinitrogen gas, with the potential to affect biogeochemical cycles. In our MAB model, this loss of regenerated nutrients through denitrification within the sediments significantly affects primary production, since recycled nitrogen supports most of the primary production in that region. The diminished primary production and consequent decrease of organic matter flux to the seafloor leads to less sediment oxygen consumption and higher oxygen concentrations in bottom waters. However, changes in regenerated nitrogen on the VIS barely affect primary production due to the efficient supply of new nutrients through wind-driven upwelling during summer and the nutrient-rich coastal current. We recommend that modelling experiments focusing on oxygen dynamics (as well as oxygen budget calculations) should include sediment denitrification in coastal regions where regenerated primary production dominates productivity.

Quantifying the role of atmospheric rivers in the interior western United States

AbstractAtmospheric rivers (ARs) have increasingly been recognized for their contribution to high‐impact weather and climate variability. A recent investigation based on observations located primarily in lowland valleys and basins of the western United States suggests that 10–50% of the total cool season (November to April) precipitation between water years 1998 and 2008 occurred on the day of and day following AR landfall (hereafter the AR fraction), as identified using Special Sensor Microwave Imager data. However, these results are based only on ARs crossing the North American west coast between 32.5°N and 52.5°N, which excludes those crossing the west coast of the Baja Peninsula. Here, we identify ARs in the ERA‐Interim reanalysis and examine the AR fraction at high‐elevation observational sites and in the NOAA/CPC Unified Daily Precipitation Analysis. At high‐elevation snowpack telemetry sites, we find good agreement with the AR fraction obtained previously for valley and basin locations. We also show that including ARs crossing the west coast of the Baja Peninsula (as far south as 24°N) substantially increases the AR fraction over the southwestern United States. Copyright © 2012 Royal Meteorological Society

Harmful algal blooms along the North American west coast region: History, trends, causes, and impacts

Along the Pacific coast of North America, from Alaska to Mexico, harmful algal blooms (HABs) have caused losses to natural resources and coastal economies, and have resulted in human sicknesses and deaths for decades. Recent reports indicate a possible increase in their prevalence and impacts of these events on living resources over the last 10–15 years. Two types of HABs pose the most significant threat to coastal ecosystems in this “west coast” region: dinoflagellates of the genera Alexandrium, Gymnodinium, and Pyrodinium that cause paralytic shellfish poisoning (PSP) and diatoms of the genus Pseudo-nitzschia that produce domoic acid (DA), the cause of amnesic shellfish poisoning (ASP) in humans. These species extend throughout the region, while problems from other HABs (e.g., fish kills linked to raphidophytes or Cochlodinium, macroalgal blooms related to invasive species, sea bird deaths caused by surfactant-like proteins produced by Akashiwo sanguinea, hepatotoxins from Microcystis, diarrhetic shellfish poisoning from Dinophysis, and dinoflagellate-produced yessotoxins) are less prevalent but potentially expanding. This paper presents the state-of-knowledge on HABs along the west coast as a step toward meeting the need for integration of HAB outreach, research, and management efforts.

Numerical study and prediction of nuclear contaminant transport from Fukushima Daiichi nuclear power plant in the North Pacific Ocean

On March 11, 2011, a large earthquake and subsequent tsunami near the east coast of Japan destroyed the Fukushima Daiichi nuclear power plant (FD-NPP), causing a massive release of nuclear contaminants. In this paper, a Pacific basin-wide physical dispersion model is developed and used to investigate the transport of nuclear contaminants. The Pacific circulation model, based on the Regional Ocean Modeling System (ROMS), is forced with air-sea flux climatology derived from COADS (the Comprehensive Ocean-Atmosphere Data Set). It is shown that ocean current dominates nuclear contaminant transport. Following the Kuroshio Extension and North Pacific Current, nuclear contaminants at the surface will move eastward in the Pacific as far as 140°W, thereafter dividing into two branches. For the south branch, nuclear contaminants will be transported westward by the equatorial current, and can reach the Philippines after 10 years’ time. In contrast, the north branch will arrive at the American west coast and then migrate to the Bering Sea. At 200 m water depth, part of the nuclear materials will move southwestward along with deep ocean circulation, which could potentially reach the east coast of Taiwan. The other part will move to the west coast of America and separate into two branches. One will move northward along the west coast of Alaska, while the other will travel southward to the Hawaiian Islands. The transport of radiation contaminants below 500 m is slow, and will primarily remain in the central Pacific. The physical dispersion model results show that high concentrations of the radioactive isotope cesium-137 (137Cs) will move eastward and reach the central Pacific and west coast of North America in two and eight years, respectively. The sea areas influenced by the nuclear contaminants continue to expand, while peak concentrations decrease in the North Pacific.

Parasites and invasions: a biogeographic examination of parasites and hosts in native and introduced ranges

AbstractAim To use a comparative approach to understand parasite demographic patterns in native versus introduced populations, evaluating the potential roles of host invasion history and parasite life history.Location North American east and west coasts with a focus on San Francisco Bay (SFB).Methods Species richness and prevalence of trematode parasites were examined in the native and introduced ranges of two gastropod host species, Ilyanassa obsoleta and Littorina saxatilis. We divided the native range into the putative source area for introduction and areas to the north and south; we also sampled the overlapping introduced range in SFB. We dissected 14,781 snails from 103 populations and recorded the prevalence and identity of trematode parasites. We compared trematode species richness and prevalence across the hosts’ introduced and native ranges, and evaluated the influence of host availability on observed patterns.Results Relative to the native range, both I. obsoleta and L. saxatilis have escaped (lost) parasites in SFB, and L. saxatilis demonstrated a greater reduction of trematode diversity and infection prevalence than I. obsoleta. This was not due to sampling inequalities between the hosts. Instead, rarefaction curves suggested complete capture of trematode species in native source and SFB subregions, except for L. saxatilis in SFB, where infection was extremely rare. For I. obsoleta, infection prevalence of trematodes using fish definitive hosts was significantly lower in SFB compared to the native range, unlike those using bird hosts. Host availability partly explained the presence of introduced trematodes in SFB.Main conclusions Differential losses of parasite richness and prevalence for the two gastropod host species in their introduced range is probably the result of several mechanistic factors: time since introduction, propagule pressure, vector of introduction, and host availability. Moreover, the recent occurrence of L. saxatilis’ invasion and its active introduction vector suggest that its parasite diversity and distribution will probably increase over time. Our study suggests that host invasion history and parasite life history play key roles in the extent and diversity of trematodes transferred to introduced populations. Our results also provide vital information for understanding community‐level influences of parasite introductions, as well as for disease ecology in general.

Phylogeography and reproductive variation of the poecilogonous polychaeteBoccardiaproboscidea(Annelida:Spionidae) along theWestCoast ofNorthAmerica

The ability to produce more than one kind of offspring, or poecilogony, is a striking example of reproductive variability. Traditionally, larval nutrition has been classified as a dichotomy: if offspring obtain nutrition from their mothers (lecithotrophy), there is lower fecundity and greater chance of offspring survival than when they get their nutrition from plankton (planktotrophy). The polychaete Boccardia proboscidea (Spionidae) produces both types of embryos using three different reproductive strategies. In this study, we examined the roles of genetic history and phenotypic plasticity on explaining natural variation in B. proboscidea along the Pacific coast of the United States using two genetic mitochondrial markers, 16S rDNA and Cyt b, and common garden experiments. These data show a single North American West Coast network that is structured, geographically, by the well-documented biogeographic break near Point Conception, California. The southern group within this network covers a smaller range, but has larger haplotype diversity, than the northern group. Some individuals differing in reproductive type had the same haplotype, indicating independence of these features; however, differences between laboratory and field data suggest additional geographic variation within one of the reproductive types. Females from higher latitudes provide offspring with larger supplies of extra embryonic nutrition than females from southern latitudes. Results herein suggest that both genetic history and developmental plasticity are playing a role in the maintenance of this reproductive polymorphism.

Swima (Annelida, Acrocirridae), holopelagic worms from the deep Pacific

Two new species of Swima, a recently established genus of annelid worms, are introduced, one from deep water off the North American West Coast and the other from the Philippines. The acrocirrid genus now contains three named species, Swima bombiviridis, Swima fulgida sp. nov., and Swima tawitawiensis sp. nov.Swima are holopelagic, occurring only in the water column, and thus far have only been observed below 2700 m. The worms are relatively large, sometimes reaching over 30 mm in length and 5 mm in width. They have gelatinous bodies and fans of long swimming chaetae, which are flattened into paddles in S. tawitawiensis sp. nov. Members of Swima are distinguished from other swimming acrocirrids by their transparent bodies, single medial subulate branchiae, and simple nuchal organs that do not skirt the bases of lateral subulate branchiae. Swima fulgida sp. nov. is distinguished from other members of the genus by its darkly pigmented anterior gut, whereas S. tawitawiensis sp. nov. is distinguished by possessing three subulate head appendages instead of just one and by the shape of its noto- and neurochaetae. Swima species possess four pairs of elliptical, transformed segmental branchiae that produce green bioluminescence when autotomized. These ‘bombs’ were observed in various states of regeneration on a single individual. Swima are neutrally buoyant, often observed hanging immobile in the water column, and are active, agile swimmers. Although not previously documented in the literature, these worms are not rare in the deep water column. Since the worms were first noticed in 2001, they have been observed on more than half of the Monterey Bay Aquarium Research Institute's midwater remotely operated vehicle dives that went to sufficient depth. The discovery of Swima underscores our lack of knowledge of deep pelagic fauna. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 163, 663–678.

Potential for resumption of East Pacific sea level rise after 30‐year hiatus

Over the course of the past century the global rate of sea level rise has increased threefold, jumping from 1 millimeter per year in the early 1900s to 3 millimeters per year in the late twentieth century. This seemingly small increase in the global average can have serious consequences when regional influences come into play, as can be the case for low‐lying islands and coastal regions with shallow shores. One locale has so far managed to escape any impact from the global trend, but that security may soon be coming to an end. Since the 1980s the sea level height off the North American West Coast has barely budged. This finding, recorded in both satellite altimetry and tidal gauge records, suggests to Bromirski et al. that something has been suppressing the local rate of sea level rise.

Long-time trends in ship traffic noise for four sites off the North American West Coast

Measurements (1994-2007) from four cabled-to-shore hydrophone systems located off the North American west coast permit extensive comparisons between "contemporary" low frequency ship traffic noise (25-50 Hz) collected in the past decade to measurements made over 1963-1965 with the same in-water equipment at the same sites. An increase of roughly 10 dB over the band 25-40 Hz at one site has already been reported [Andrew et al., Acoust. Res. Lett. Online 3(2), 65-70 (2002)]. Newly corrected data from the remaining three systems generally corroborate this increase. Simple linear trend lines of the contemporary traffic noise (duration 6 to 12+ years) show that recent levels are slightly increasing, holding steady, or decreasing. These results confirm the prediction by Ross that the rate of increase in traffic noise would be far less at the end of the 20th century compared to that observed in the 1950s and 1960s.

Early marine migration patterns of wild coastal cutthroat trout (Oncorhynchus clarki clarki), steelhead trout (Oncorhynchus mykiss), and their hybrids.

BackgroundHybridization between coastal cutthroat trout (Oncorhynchus clarki clarki) and steelhead or rainbow trout (Oncorhynchus mykiss) has been documented in several streams along the North American west coast. The two species occupy similar freshwater habitats but the anadromous forms differ greatly in the duration of marine residence and migration patterns at sea. Intermediate morphological, physiological, and performance traits have been reported for hybrids but little information has been published comparing the behavior of hybrids to the pure species.Methodology/Principal FindingsThis study used acoustic telemetry to record the movements of 52 cutthroat, 42 steelhead x cutthroat hybrids, and 89 steelhead smolts, all wild, that migrated from Big Beef Creek into Hood Canal (Puget Sound, Washington). Various spatial and temporal metrics were used to compare the behavior of the pure species to their hybrids. Median hybrid residence time, estuary time, and tortuosity values were intermediate compared to the pure species. The median total track distance was greater for hybrids than for either cutthroat or steelhead. At the end of each track, most steelhead (80%) were located near or north of the Hood Canal, as expected for this seaward migrating species, whereas most cutthroat (89%) were within 8 kilometers of the estuary. Most hybrids (70%) were detected leaving Hood Canal, though a substantial percentage (20%) remained near the Big Beef Creek estuary. More hybrids (7.5%) than pure cutthroat (4.5%) or steelhead (0.0%) were last detected in the southern reaches of Hood Canal.Conclusions/SignificanceGiven the similarity in freshwater ecology between the species, differences in marine ecology may play an important role in maintaining species integrity in areas of sympatry.

Discovery of a Gall-Forming Midge, Asphondylia pilosa Kieffer (Diptera: Cecidomyiidae), on Scotch Broom (Cytisus scoparius (L.) Link) (Fabaceae)

Scotch broom (Cytisus scoparius: (L.) Link), a native European perennial shrub, was introduced to the U.S. before the turn of the century as an ornamental for its bright yellow, pea-like flower. The plant found the western U.S. maritime zone to be an ideal habitat, thus it soon escaped from cultivation, and became an invasive weed now widely distributed from northern California to British Columbia. The massive monocultures that Scotch broom forms replace desirable species and cause allergy problems when flowering in spring. This has elevated it to one of the most important weeds in the northwest coast of the U.S.A. (Parker et al., 1994; Radtke and Davis, 2000). In an effort to control this weed, the USDA Agricultural Research Service (ARS) in Albany, California targeted this plant in the 1960’s for biological control and subsequently introduced and released two biocontrol agents, a seed-feeding weevil, Apion fuscirostre Fabricius (Coleoptera: Apionidae), and a small stem-mining moth, Leucoptera spartifoliella Hubner (Lepidoptera: Lyonetidae) (Andres and Coombs, 1995; Goeden, 1978; Julien, 1992). Both readily established, but it was discovered soon after the introduction of L. spartifoliella that it had been previously accidentally introduced and was already established in the northern part of the range of this weed (Frick, 1964). Neither of these agents provided effective control of Scotch broom. Therefore, in the mid-1990’s, U.S. Forest Service and the Oregon Department of Agriculture joined an on-going program with New Zealand (Landcare Research, Lincoln) and Australia (CSIRO, Canberra); two countries in which Scotch broom is also a major weed (Syrett et al., 1999). Between 1996 and 2000, a major effort of this program was to support research at CABI Bioscience at Silwood Park, England to conduct surveys of the natural enemies of Scotch broom and identify and study those that had potential as biocontrol agents. To prevent a repeat of the earlier program in which the agent, L. spartifoliella, had been selected, tested, and introduced only to find out afterwards it was already present, the new program included a survey to determine if any other European natural enemies were already present and attacking Scotch broom on the North American West Coast. A technician (C. J. Horning) was stationed at Florence, Oregon at the headquarters of the U.S. Forest Service’s Mapleton Ranger District to conduct this survey. The first discovery occurred when the gall mite. Aceria genistae (Nalepa) (Acarinai Eriophyidae), one of the agents being evaluated in Europe, was discovered by acarologists in California after they had become aware of the new program (Chan and Turner, 1998). The second agent, which we discovered already established on the West Coast, was the small gallforming midge. Asphondylia pilosa Kieffer which was very closely related to a second species, A. sarothamni Loew, which was being tested in Europe as a potential biocontrol agent. The remainder of this paper reviews what we have learned of the biology, distribution, and taxonomy of this insect.

Risk of giant quake off American west coast goes up

A magnitude 8 or greater earthquake has a one in three chance of hitting in the next 50 years.

Long-time trends in low-frequency traffic noise for four sites off the North American west coast.

Measurements from four cabled-to-shore hydrophone systems located off the North American west coast permit extensive comparisons between “contemporary” low-frequency traffic noise (25–50 Hz) collected in the past decade to measurements made in the mid-1960s with the same in-water equipment at the same sites. An increase of roughly 10 dB over the band 25–40 Hz at one site has already been reported [Andrew et al., ARLO Acoust. Res. Let. Online 3 (2002)]. Newly corrected data from the remaining three systems corroborate this increase. Simple linear trend lines of the contemporary traffic noise (duration 6–12+ years) show that the current levels either hold steady or decrease at three of the four sites. These results confirm the Ross prediction, at least at these sites, that the rate of increase in traffic noise would be far less at the end of the last century compared to that observed in the 1950s and 1960s.

A Lagrangian Climatology of Tropical Moisture Exports to the Northern Hemispheric Extratropics

Abstract Case studies have shown that heavy precipitation events and rapid cyclogenesis in the extratropics can be fueled by moist and warm tropical air masses. Often the tropical moisture export (TME) occurs through a longitudinally confined region in the subtropics. Here a comprehensive climatological analysis of TME is constructed on the basis of seven-day forward trajectories started daily from the tropical lower troposphere using 6-hourly 40-yr ECMWF Re-Analysis (ERA-40) data from the 23-year period 1979–2001. The objective TME identification procedure retains only those trajectories that reach a water vapor flux of at least 100 g kg−1 m s−1 somewhere north of 35°N. The results show four distinct activity maxima with different seasonal behavior: (i) The “pineapple express,” which connects tropical moisture sources near Hawaii with precipitation near the North American west coast, has a marked activity maximum in boreal winter. (ii) TME over the west Pacific is largest in summer, partly related to the East Asian monsoon and the mei-yu–baiu front. This region alone is responsible for a large portion of TME across 35°N. (iii) The narrow activity maximum over the Great Plains of North America is rooted over the Gulf of Mexico and the Caribbean Sea and has a clear maximum in summer and spring. (iv) TME over the western North Atlantic shows the smallest annual cycle with a maximum in winter and autumn. The interannual variability of (i) and (iv) is significantly modulated by El Niño. Over the African–European–Asian region, high orographic barriers impede TME. A typical TME trajectory evolution is poleward and quasi-horizontal in the subtropics and then more eastward and upward in the southern midlatitudes, where TME contributes up to 60% to climatological precipitation. The TME dataset presented here can serve as a basis for future studies on extreme events.

Reconstructing the range expansion and subsequent invasion of introduced European green crab along the west coast of the United States

The European green crab, Carcinus maenas, was first documented in San Francisco Bay in 1989, and has since spread north along the west coast of North America. The spread of this invasion has not been a smooth expansion, which has raised questions about the underlying causes of variation in recruitment. We modeled larval development and transport along the West Coast by employing an individual-based model that incorporated oceanographic model output of water temperature and ocean currents at fine spatial and temporal scales. The distance that larvae were advected depended primarily on the timing of larval release. However, the effect of seasonal ocean currents varied across latitude and years. Our results imply that the furthest northern transport from California occurs when larvae are released from Humboldt Bay during the fall of an El Nino year, making this a particularly risky time for invasion to Oregon and Washington estuaries. To precisely predict future spread and potential impacts of green crab, we recommend further empirical research to determine the precise timing of larval release and seasonal abundance of green crab larvae from North American west coast populations.

Weather Regimes and Forecast Errors in the Pacific Northwest

Abstract Despite overall improvements in numerical weather prediction and data assimilation, large short-term forecast errors of sea level pressure and 2-m temperature still occur. This is especially true for the west coast of North America where short-term numerical weather forecasts of surface low pressure systems can have large position and central pressure errors. In this study, forecast errors of sea level pressure and temperature in the Pacific Northwest are related to the shape of the large-scale flow aloft. Applying a hierarchical limited-contour clustering algorithm to historical 500-hPa geopotential height data produces four distinct weather regimes. The Rockies ridge regime, which exhibits a ridge near the axis of the Rocky Mountains and nearly zonal flow across the Pacific, experiences the highest magnitude and frequency of large sea level pressure errors. On the other hand, the coastal ridge regime, which exhibits a ridge aligned with the North American west coast, experiences the highest magnitude and frequency of large 2-m minimum temperature errors.

GLOBAL WARMING COULD CANCEL `JOURNEY OF A THOUSAND MILES'

[Extract] Pacific salmon–among the 'elite' athletes of the sea–hatch in rivers, spend their adult years in the ocean, and then make one last incredible journey up-river to reproduce in their natal streams. This final trek, or spawning run, returns 10 million salmon to North American west coast rivers annually where, for up to 1000 km, they encounter turbulent currents, narrow deep gorges (particularly the Fraser River's appropriately named Hell's Gate) and fluctuating temperatures. However, humans may have created a new hurdle that salmon may not be able to overcome. Tony Farrell and his colleagues in Canada suggest that increasing river temperatures profoundly affect the salmon's athletic capacity, and are largely responsible for salmon vanishing from their migration routes.

A central California coastal ocean modeling study: 1. Forward model and the influence of realistic versus climatological forcing

We report on a numerical simulation of the California Current circulation using the Regional Ocean Modeling System model, focusing on the region of northern and central California during the 5‐year period from 2000 to 2004. Unlike previous model studies of the California Current System, the present configuration is characterized by both realistic external forcing and a spatial domain covering most of the North American West Coast. Specifically, this configuration is driven at the surface by high‐resolution meteorological fields from the Coupled Ocean‐Atmosphere Mesoscale Prediction System and at the lateral open boundaries by output from the project Estimating the Circulation and Climate of the Ocean supported by the Global Ocean Data Assimilation Experiment. The simulation is evaluated favorably through quantitative comparisons with the California Cooperative Fisheries Investigations data set, satellite‐derived sea surface temperature, and surface drifters–derived eddy kinetic energy. The impact of adopting realistic versus climatological surface forcing is demonstrated by comparing mean and mesoscale circulation characteristics. Realistic surface forcing qualitatively alters the seasonal cycle of the mean alongshore jet and better reproduces the summer spatial structure and intensity of the eddy kinetic energy field along the central California coast.