In this study, we assessed trophic interactions between microplankton and copepods by studying the functional response of egg production rates (EPR; eggs female⁻¹day⁻¹) of the copepod Calanus marshallae to variations in microplankton biomass, species composition and community structure. Female C. marshallae and phytoplankton water samples were collected biweekly at an...
Coastal upwelling in the northern California Current
varies seasonally, with downwelling in winter and upwelling
in summer, resulting in pronounced variability in
hydrography, nutrients, phytoplankton biomass, and species
composition. Winter was characterized by moderate concentrations
of nitrate and silicate (averages of 10 and 18 μM,
respectively) and low concentrations of...
Ceria nanoparticles are of interest owing to their interesting properties like photo-absorption and ability to absorb oxygen. Several batch synthesis routes exist however these methods often lack particle size control, result in agglomeration and typically require high temperature processing. In this paper, a continuous flow microchannel synthesis method based on...
The synchrony between coastal and shelf-slope copepod communities was investigated in the northern California Current (NCC) system, a strong upwelling zone, using time series of zooplankton sampled from a nearshore station (9 km offshore, water depth 62 m) and a shelf-slope station (46 km offshore, water depth 297 m). Long-term...
This study addresses the occurrence, severity, and extent of hypoxia over the continental shelf of the northern
California Current (40–48.5°N latitude) from 1998 to 2012. Clear seasonal trends exist in the timing and duration
of hypoxia. The highest bottom-water dissolved oxygen concentrations occurred from November to March, and
levels below...
Colloidal lead selenide nanoparticles (PbSe NPs) were synthesized using a microwave-assisted continuous flow reactor. Rapid heating of precursors was performed in the microwave reaction zone to initiate nucleation and was followed by an oil bath growth zone. In this study we have evaluated the effect of the nucleation temperature on...
Alongshore transport was estimated from the gridded AVISO altimeter data and water level data from NOAA tide gauges (1993–2010) for the northern California Current (NCC) system. The biomass of the cold neritic copepods including Calanus marshallae, Pseudocalanus mimus and Acartia longiremis (dominants in the eastern Bering Sea, coastal Gulf of...
In the current study a thermally activated cooling system that combines an ORC system with a vapor compression cooling cycle was developed and tested under laboratory conditions. This combined system
can utilize waste heat or other thermal sources such as solar and geothermal to generate power and
cooling. Hot oil...
Filtration by adult Euphausia pacifica was measured before and during the upwelling season, using both “disappearance of chlorophyll” and “disappearance of cells” techniques. Results show that feeding rates and selectivity varied with food assemblages. Filtration rate (F) was best modeled by the Ivlev function: the average F on total Chl-a...
Previous research has suggested that the use of more authentic learning activities can produce more robust and durable knowledge gains. This is consistent with calls within civil engineering education, specifically hydrology, that suggest that curricula should more often include professional perspective and data analysis skills to better develop the ‘T-shaped’...
Previous research has suggested that the use of more authentic learning activities can produce more robust and durable knowledge gains. This is consistent with calls within civil engineering education, specifically hydrology, that suggest that curricula should more often include professional perspective and data analysis skills to better develop the "T-shaped"...
Through the use of conditional compilation and related tools, many software projects can be used to generate a huge
number of related programs. The problem of typing such variational software is difficult. The brute-force strategy
of generating all variants and typing each one individually is (1) usually infeasible for efficiency...
Back-calculation of length-at-age from otoliths and spines is a common technique employed in fisheries biology, but few studies have compared the precision of data collected with this method for catfish populations. We compared precision of back-calculated lengths-at-age for an introduced Ictalurus furcatus (Blue Catfish) population among 3 commonly used cross-sectioning...
Desert springs are sensitive aquatic ecosystems that pose unique challenges to natural resource managers and researchers. Among the most important of these is the need to accurately quantify population parameters for resident fish, particularly when the species are of special conservation concern. We evaluated the efficiency of baited minnow traps...
During the summer of 1994, 1996, and 1997, we conducted hydrographic and plankton surveys of the upper 70 m in the nearshore, the continental shelf, and off shelf oceanic waters off Oregon, USA. Copepod densities and biomass were estimated along 4 transects from each cruise. The on shelf copepod biomass...
Unusual collections of several euphausiid, chaetognath, and copepod species help elucidate
the effects of the strong 1997/1998 El Niño off the central Oregon, USA, coast. Furcilia of Nyctiphanes simplex, a euphausiid typically found only as far north as central California, were collected in bi-weekly nearshore samples between December 1997 and...
An introduced population of European green crabs Carcinus maenas was established in San Francisco Bay (California, USA) prior to 1989. Subsequently, their larvae were likely carried northward into the embayments of Oregon, Washington (USA), and British Columbia (Canada) by the unusually strong Davidson Current during the winter of the El...
The zooplankton of the northern California Current are typically characterized by an abundance of lipid-rich copepods that support rapid growth and survival of ecologically, commercially, and recreationally valued fish, birds, and mammals. Disruption of this food chain and reduced ecosystem productivity are often associated with climatic variability such as El...
1. The evaluation of the age and growth of animal populations is essential for understanding and
predicting how populations will respond to changes in environmental conditions and anthropogenic
stressors.
2. We used a novel, von Bertalanffy hierarchical modelling approach to quantify relationships between
the growth of three freshwater mussel species...
Diets of juvenile coho Oncorhynchus kisutch and Chinook O. tshawytscha salmon
are made up primarily of winter-spawning fish taxa in the late-larval and early juvenile stages that
are undersampled in plankton and larger trawl nets. Although we have no direct measure of the
availability of fish prey important to juvenile...
We compared brood sizes among adult female Euphausia pacifica Hansen, 1911 from 3
populations in the North Pacific: Puget Sound, Washington, USA; Toyama Bay, Japan; and the Oregon coast, USA. Additionally, we used multiple linear regression models to compare the interspecific brood size as a function of female length and...
North American freshwater mussels have been subjected to multiple stressors in recent decades that have contributed to declines in the status and distribution of many species. However, considerable uncertainty exists regarding the relative influence of these factors on observed population declines. 2. We used an occupancy modelling approach to quantify...
Gravid adult female Euphausia pacifica were collected off Newport, Oregon, USA and transferred to the laboratory, where females spawned eggs, eggs hatched, and larvae were reared at 10.5 degrees C. We fed 4 cohorts of larvae to excess with a combination of phytoplankton species and monitored them daily until they...
Early ocean residence is considered a critical period for juvenile salmon although specific survival mechanisms are often unidentified and may vary by species or life stage. Columbia River spring-run Chinook salmon Oncorhynchus tshawytscha abundance has declined dramatically since the early 1900s. To elucidate mechanisms of early marine survival, we tested...
The Moult Rate (MR) method has been used widely to derive stage-specific growth rates in juvenile copepods. It is the most common field-based method. Unfortunately, the equation underlying the method is wrong and, consequently, large errors in juvenile growth rate estimates are widespread. The equation derives growth from the mean...
In coastal South Carolina, most impounded marshes are managed for waterfowl; fewer are managed for fishes. Tidal control is central to each strategy but raises concerns that nursery function could be impaired. This research examined the assemblage composition of fishes during early-life stages. We sampled two impoundments of each management...
Fish monitoring programs often rely on the collection, species identification, and counting of individual fish over time to inform natural resource management decisions. Thus, the utility of the data used to inform these decisions can be negatively affected by species misidentification. Fish species misidentification bias can be minimized by confirming...
Summertime wind stress along the coast of the northwestern United States typically exhibits intraseasonal oscillations (ISOs) with periods from ≈15 to 40 days, as well as fluctuations on the 2- to 6-day “weather-band” and 1-day diurnal time scales. Coastal upwelling of cool, nutrient-rich water is driven by extended periods of...
Generalized additive models (GAMs) were used to investigate the relationships between annual recruitment of natural coho salmon (Oncorhynchus kisutch) from Oregon coastal rivers and indices of the physical ocean environment. Nine indices were examined, ranging from large-scale ocean indicators, e.g., Pacific Decadal Oscillation (PDO), to indicators of the local ecosystem...
Infection with Helicobacter pylori is a major risk factor for the development of gastric cancer, and infection with strains carrying the virulence factor CagA significantly increases this risk. To investigate the mechanisms by which CagA promotes carcinogenesis, we generated transgenic zebrafish expressing CagA ubiquitously or in the anterior intestine. Transgenic...
The impact of mesoscale eddies on the spatial distribution of zooplankton biomass was analysed using data from the Arabian Sea and the Black Sea. The highest values of spatial variance of zooplankton biomass in the upper 100 to 150 m were found in regions with maximum available potential energy of...
Most pathogen detection tests are imperfect, with a sensitivity < 100%, thereby resulting in the potential for a false negative, where a pathogen is present but not detected. False negatives in a sample inflate the number of non-detections, negatively biasing estimates of pathogen prevalence. Histological examination of tissues as a...
Research on regulatory mechanisms in biological populations often focuses on environmental covariates. An integrated
approach that combines environmental indices with organismal-level information can provide additional insight on
regulatory mechanisms. Survival of spring/summer Snake River Chinook salmon (Oncorhynchus tshawytscha) is consistently
low whereas some adjacent populations with similar life histories experience...
Larval supply determines year-class strength of fisheries and complex ecological
interactions among adults of benthic marine species. In upwelling regions, a latitudinal cline in
the intensity and persistence of upwelling is thought to affect larval advection and recruitment,
thereby regulating the intensity of interactions in adult populations and communities. We...
We model the evolution of eukaryotic protein-protein interaction (PPI) networks. In our model, PPI networks evolve by two known biological mechanisms: (1) Gene duplication, which is followed by rapid diversification of duplicate interactions. (2) Neofunctionalization, in which a mutation leads to a new interaction with some other protein. Since many...
The copepod Tigriopus californicus shows extensive population divergence and is becoming a model for understanding allopatric differentiation and the early stages of speciation. Here, we report a high-quality reference genome for one population (similar to 190 megabases across 12 scaffolds, and similar to 15,500 protein-coding genes). Comparison with other arthropods...
Fisheries oceanography is the study of ecological relationships between fishes and the dynamics of their marine environments and aims to characterize the physical, chemical, and biological factors that affect the recruitment and abundance of harvested species. A recent push within the fisheries management community is toward ecosystem-based management. Here, we...
This study uses derivative spectroscopy to assess qualitative and quantitative information regarding seafloor types that can be extracted from hyperspectral remote sensing reflectance signals. Carbonate sediments with variable concentrations of microbial pigments were used as a model system. Reflectance signals measured directly over sediment bottoms were compared with remotely sensed...
The state of the California Current System (CCS)
since spring 2011 has evolved in response to dissipation
of La Niña through spring and summer, resurgence of
cooler La Niña conditions in fall and winter, and finally
a transition towards ENSO-neutral conditions in spring
2012. The resurgence of La Niña was...
In 2013, the California current was dominated by
strong coastal upwelling and high productivity. Indices
of total cumulative upwelling for particular coastal
locations reached some of the highest values on record.
Chlorophyll a levels were high throughout spring and
summer. Catches of upwelling-related fish species were
also high. After a...
Euphausiid krill play a critical role in coastal and oceanic food webs, linking primary producers to upper trophic levels. In addition, some species support commercial fisheries worldwide. Despite their ecological importance, the genetics of these important species remain poorly described. To improve our understanding of the genetics of these ecological...
The community of trophically transmitted marine parasites of juvenile coho (Oncorhynchus kisutch) and Chinook
(Oncorhynchus tshawytscha) salmon across 8 years (2002–2009) was related to indices of physical and biological ocean conditions
and adult returns. When the biomass of lipid-poor, southern origin copepods in the coastal ocean was high during juvenile...
We have applied a normalized difference algorithm to 8 day composite chlorophyll-a (CHL) and fluorescence line height (FLH) imagery obtained from the Moderate Resolution Imaging Spectroradiometer aboard the Aqua spacecraft in order to detect and monitor phytoplankton blooms in the Oregon coastal region. The resulting bloom products, termed CHL[subscript rel]...
The maintenance of pH homeostasis is critical for a variety of cellular metabolic processes. Although ocean acidification is likely to influence cellular metabolism and energy balance, the degree to which intracellular pH in phytoplankton differs from the external environment under varying environmental pH levels is not well characterized. While there...
Factors influencing soil organic matter (SOM) stabilization and dissolved organic carbon (DOC) content in complex terrain, where vegetation, climate, and topography vary over the scale of a few meters, are not well understood. We examined the spatial correlations of lidar and geographic information system-derived landscape topography, empirically measured soil characteristics,...
Post-fire forest management commonly requires accepting some negative ecological impacts from management activities in order to achieve management objectives. Managers need to know, however, whether ecological impacts from post-fire management activities are transient or cause long-term ecosystem degradation. We studied the long-term response of understory vegetation to two post-fire logging...
Phytoplankton species were enumerated from 72 samples collected biweekly during the upwelling season (May to August) of 2001−2010 to test for effects of interannual variations in upwelling and decadal basin-scale variability on phytoplankton species composition and community structure. Cluster analysis of phytoplankton community structure identified 7 groups; 1 group was...
The state of the California Current system (CCS) since spring 2010 has evolved in response to the development of cooler La Nina following the dissipation of the relatively weak and short-lived El Nino event of 2009-2010. The 2009-2010 El Nino appears to have dissipated quite rapidly in early spring 2010,...
Euphausia pacifica occupy a remarkably wide range of ecosystems. We examined the
differences in brood sizes from eight regions of the North Pacific to explore how variation
in the brood size might contribute to their success over such a range. We show
a compilation and analysis of short-term E. pacifica...
Seabirds have often been proposed as environmental indicators. Beached bird data may provide an additional data source and such data is efficacious because it can reliably be collected by volunteers. In addition to anthropogenic factors, such as oil spills, changes in the ocean-atmosphere can affect carcass beaching rate in 3...