Northern California Coast Research Articles

On the Source of Organic Acid Aerosol Layers above Clouds

During the July 2005 Marine Stratus/Stratocumulus Experiment (MASE) and the August-September 2006 Gulf of Mexico Atmospheric Composition and Climate Study (GoMACCS), the Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) Twin Otter probed aerosols and cumulus clouds in the eastern Pacific Ocean off the coast of northern California and in southeastern Texas, respectively. An on-board particle-into-liquid sampler (PILS) quantified inorganic and organic acid species with < or = 5-min time resolution. Ubiquitous organic aerosol layers above cloud with enhanced organic acid levels were observed in both locations. The data suggest that aqueous-phase reactions to produce organic acids, mainly oxalic acid, followed by droplet evaporation is a source of elevated organic acid aerosol levels above cloud. Oxalic acid is observed to be produced more efficiently relative to sulfate as the cloud liquid water content increases, corresponding to larger and less acidic droplets. As derived from large eddy simulations of stratocumulus underthe conditions of MASE, both Lagrangian trajectory analysis and diurnal cloudtop evolution provide evidence that a significant fraction of the aerosol mass concentration above cloud can be accounted for by evaporated droplet residual particles. Methanesulfonate data suggest that entrainment of free tropospheric aerosol can also be a source of organic acids above boundary layer clouds.

Sources and sinks of hydroxyl radical in sea‐salt particles

We have examined the photochemical formation of hydroxyl radical (•OH) in aqueous extracts of supermicron sea‐salt particulate matter (SS PM) collected from the coast of northern California. All extracts formed •OH during illumination, indicating that this process is widespread in sea‐salt particles. Scaling extract results to SS PM conditions reveals that in situ rates of •OH photoformation are typically 100–1000 μM hr−1 in midlatitude sea‐salt particles (summer, midday, 88% relative humidity). These rates are comparable to calculated rates of partitioning of gas phase •OH to the particles and are 3–4 orders of magnitude greater than •OH photoformation rates in surface seawater. Photolysis of nitrate was a dominant source of •OH in the particle extracts, accounting for an average of 59 ± 25% of its formation. The other sources of •OH have not been identified, but photolysis of organic compounds derived from seawater is likely important. The lifetimes of •OH in the sea‐salt particles are of the order of 10−9–10−8 s and are primarily controlled by reactions with unidentified, but probably organic, compounds. Bromide and chloride are also significant sinks of •OH, typically accounting for approximately 25% of its loss. The rapid formation and destruction of •OH in sea‐salt particles likely significantly affects the chemistry of halides, organic compounds, and other reduced species in SS PM. In turn, these particle reactions probably alter the budgets of gases such as ozone and volatile organic compounds in the marine boundary layer.

Identifying the Species of Bats Roosting in Redwood Basal Hollows using Genetic Methods

Bats frequently use basal hollows in trees to gain access to interior roost sites but it has been challenging to verify which species do so because it is difficult to capture bats or identify bats using acoustic methods at these locations. We employed noninvasive genetic sampling of guano to identify the species of bats that use basal hollows in redwood (Sequoia sempervirens) trees in coastal northern California. Guano was collected using screen traps suspended within the hollows of trees in the northern and central range of the redwood, in Del Norte and Mendocino County, California, respectively. A representative sample of 231 guano pellets from 104 trees was selected for analysis; 149 pellets from 63 trees amplified sufficiently for genetic sequencing. Species identification is possible for 8 of the 11 species that were assumed to occur in the study area, based on previous studies using two 190 bp regions of the 16S ribosomal subunit gene. Seven distinct species, subspecies or species groups were identified; all 7 were represented from samples in the northern study area whereas only 5 of these occurred within the central study area. The long-legged bat (Myotis volans) was the most frequent taxa identified. Genetic sampling to identify the species using roosts will be an important contribution to the conservation of bats. This method is noninvasive and appears more efficient than other methods, such as following radio-marked bats to basal hollows or attempting to capture bats as they enter or leave a hollow. New laboratory developments in this field, such as microarrays, when combined with sequencing, will open up domains of research on individual species and species composition at various temporal and geographic scales.

STOPOVER ECOLOGY AND HABITAT SELECTION OF JUVENILE SWAINSON'S THRUSHES DURING FALL MIGRATION ALONG THE NORTHERN CALIFORNIA COAST

Abstract We investigated selection of stopover habitat by juvenile Swainson's Thrushes (Catharus ustulatus) during fall migration at a site along the northern California coast. The study site vegetation consisted mainly of coniferous forest (pine [Pinus] and spruce [Picea]), with interspersed patches of broadleaf forest (willow [Salix] and alder [Alnus]) in poorly drained swales. For 26 birds captured and radio-tracked in 2002 and 2003, the average minimum stopover duration was 8.9 ± 1.0 days. For 20 of these birds with a sufficient number of locations, the average home range size was 1.9 ± 0.3 ha. Thrushes showed no overall pattern of selection for forest type within the study area or for forest type used inside their home range. Fat and lean birds selected forest types similarly within the study area and their home ranges. However, locations occupied by lean birds had twice as much huckleberry (Vaccinium ovatum) shrub cover and were 1.3 times more concealed by vegetation than locations occupied by fat b...

AGE-RELATED SURVIVAL AND BEHAVIOR OF SNOWY PLOVER CHICKS

Precocial young often experience high mortality prior to achieving flight, especially in the first days after hatching. We quantified relationships between chick age, survival, behavior, and response to natural and anthropogenic danger for the threatened Western Snowy Plover (Charadrius alexandrinus nivosus) in coastal northern California, USA. Plover chicks were most likely to die in the first three days of their 28-day prefledging period, especially on sandy ocean beaches compared to coarser substrates of river habitats. Chick survival in both habitats increased across the ,120-day chick-rearing period. Improved survival of older chicks coincided with an age-related reduction in brooding and increased distance from the tending parent, which was not related to season. Lower survival of younger chicks was correlated with a tendency to lie motionless when approached by humans; nearly all older chicks responded to human approach by running to evade danger. Chicks of all ages were more likely to lie motionless when potential avian predators flew nearby. Age-dependent survival of Snowy Plover chicks paralleled a trend of increasing development, thermal independence from adults, and capability of evading predators.

LITOSPHAERIDIUM TOO: TWO NEW DINOFLAGELLATE CYST SPECIES FROM THE CRETACEOUS OF CALIFORNIA

Abstract The ‘Middle’ Cretaceous of the Northern California Coast Ranges has yielded unusually well-preserved specimens of Litosphaeridium, some of which (Litosphaeridium arundum, Litosphaeridium bacar, Litosphaeridium conispinum, and Litosphaeridium siphoniphorum subsp. glabrum) have been analyzed in detail previously. Two other species, which were discovered later, are Litosphaeridium adnatum sp. nov. and Litosphaeridium gaponoffiae sp. nov. Litospheridium adnatum sp. nov. is most similar to Litosphaeridium siphoniphorum, but has an adnate operculum, sulcal processes, a more elongate central body, and less of the central body is covered by processes. The other, Litosphaeridium gaponoffiae sp. nov., is most similar to Litosphaeridium arundum and Litospheridium fucosum, but has goblet-shaped processes, a free operculum, a more spherical central body, and its cingular processes are not reduced as they are in Litospheridium arundum. The two species are from the late Albian based on the associated dinoflagel...

Geodetic constraints on areal changes in the Pacific–North America plate boundary zone: What controls Basin and Range extension?

Using ∼1500 geodetic velocities we model the present-day spatial patterns of areal changes inside the Pacific–North America plate boundary zone. From this model we show that between the central Gulf of California and the Queen Charlotte Islands there is no significant net change in surface area. This zero net areal-change result allows us to relate regions of areal growth to areas of equivalent contraction elsewhere within the plate boundary zone. We find that areal growth of the Basin and Range province (BRP) and its eastern margin (∼5.2 ± 0.1 × 10 3 m 2 /yr) is balanced by areal reduction near northwestern California between 38°N and 42°N. The San Andreas fault system south of 38°N and the plate boundary zone north of ∼42°N (including the Juan de Fuca and Gorda Ridge systems) each have no significant net areal change. Our results suggest a kinematic relationship between extension in the BRP and contraction near the northern California Coast Ranges and Klamath Mountains. From these observations we propose that, although BRP extension may be caused by internal forces, the southernmost Cascadia subduction zone provides a “window of escape” that acts as a stress guide to BRP extension as well as northwestward Sierra Nevada motion. Such a dynamic model is consistent with independent findings that (1) the least principal horizontal stress orientations in the BRP are toward northern California, (2) extension directions in the BRP have changed orientation to track the northward migration of the Mendocino triple junction, and (3) the southernmost Cascadia subduction zone is a relatively weak plate boundary.

The Relationship Between Productivities of Salmonids and Forest Stands in Northern California Watersheds

Abstract Productivities of resident salmonids and upland and riparian forests in 22 small watersheds of coastal northern California were estimated and compared to determine whether: 1) upland site productivity predicted riparian site productivity; 2) either upland or riparian site productivity predicted salmonid productivity; and 3) other parameters explained more of the variance in salmonid productivity. Upland and riparian site productivities were estimated using Site Index values for redwood (Sequoia sempervirens) and red alder (Alnus rubra), respectively. Salmonid productivity was indexed by back-calculated length at age 1 of the largest individuals sampled and by total biomass. Upland and riparian site indices were correlated, but neither factor contributed to the best approximating models of salmonid productivity. Total salmonid biomass was best described by a positive relationship with drainage area. Length of dominant fish was best described by a positive relationship with percentage of hardwoods within riparian areas, which may result from nutrient and/or litter subsidies provided by red alder. The inability of forest productivity to predict salmon productivity may reflect insufficient variation in independent variables, limitations of the indices, and the operation of other factors affecting salmonid production. The lack of an apparent relationship between upland conifer and salmonid productivity suggests that management of land for timber productivity and component streams for salmonid production in these sites will require separate, albeit integrated, management strategies.

Late Neogene and Quaternary landscape evolution of the northern California Coast Ranges: Evidence for Mendocino triple junction tectonics

A landscape records the surface response to tectonics at time scales intermediate between short time-scale information derived from seismic imaging and global positioning systems and the long-term geologic record. We link late Neogene and Quaternary deposits and landforms in the northern California Coast Ranges to the tectonics of the Mendocino triple junction. In the northern California Coast Ranges, the Mendocino crustal conveyor geodynamic model describes crustal thickening, thinning, and dynamic topography that produce a pattern of uplift that migrates northward with the Mendocino triple junction. The tectonics are manifest in the drainage system and elevation pattern of the Coast Ranges. At long wavelengths, the elevation pattern closely matches the predicted double-peaked shape of Mendocino crustal conveyor topography, and the high points of uplift control the location of drainage divides. Presently, the divide between the Russian and Eel Rivers and the divide between the Eel and Van Duzen Rivers approximately correspond to the peaks of uplift predicted by the Mendocino crustal conveyor model. As the triple junction migrates northward, the double-humped pattern of uplift and subsidence migrates, and the Coast Ranges emerge. Smaller drainages develop and evolve by stream capture and flow reversal, and the two main divides migrate in concert with the triple junction. In contrast to the systematic development of the small streams, the largest trunk streams can maintain grade through regions of high uplift, and coastal river mouths remain stationary despite the uplift moving north. Before ca. 2 Ma, the majority of the Coast Range drainage flowed to a southern coastal outlet near the present mouth of the Russian River. At 2 Ma, facilitated by headwater stream capture at key locations, the drainage direction reversed, and the majority of Coast Range rivers now drain into the north-flowing Eel River. The major drainage reorganization at 2 Ma highlights the potential for complexity in geomorphic response to tectonics.

Factors controlling the age structure of Margaritifera falcata in 2 northern California streams

Freshwater mussels are long-lived and relatively stationary organisms that form annual rings, so they provide excellent opportunities for studying how population properties such as age structure relate to environmental influences on recruitment and mortality. We investigated population dynamics of the freshwater pearl mussel, Margaritifera falcata, in 2 northern California Coast Range rivers, the South Fork Eel and the Navarro. We used field observations and inverse theoretical modeling to assess age structures and identify factors that control population demographics. Distinctly different mortality rates for young (<20 y) and old (≥20 y) mussels were observed in the South Fork Eel, and recruitment and mortality both were related to river discharge regimes. Margaritifera falcata recruited more successfully during low-discharge than during high-discharge years, and a 2-fold increase in discharge caused a 60% decline in recruitment success. Active annual recruitment (˜1100–1800 ind./y) was observed in the South Fork Eel, whereas recruitment has been low or nonexistent during the past 30 y in the Navarro. This difference probably is a consequence of the influence of 2 non-mutually exclusive factors: landuse history and host-fish abundance. The Navarro watershed has extensive timber harvesting and orchard/vineyard agriculture and has had severe declines in fish populations, whereas large sections of the South Fork Eel pass through protected land and the river has retained its historical fish populations. Investigation of the factors that shape local M. falcata population age structures yielded insights into the influence of environmental variables and history on mortality and recruitment that will aid conservation of this endangered family.

A Multiwinter Analysis of Channeled Flow through a Prominent Gap along the Northern California Coast during CALJET and PACJET

Abstract Experimental observations from coastal and island wind profilers, aircraft, and other sensors deployed during the California Land-falling Jets Experiment of 1997/98 and the Pacific Land-falling Jets Experiment of 2000/01–2003/04 were combined with observations from operational networks to document the regular occurrence and characteristic structure of shallow (∼400–500 m deep), cold airstreams flowing westward through California’s Petaluma Gap from the Central Valley to the coast during the winter months. The Petaluma Gap, which is the only major air shed outlet from the Central Valley, is ∼35–50 km wide and has walls extending, at most, a modest 600–900 m above the valley floor. Based on this geometry, together with winter meteorological conditions typical of the region (e.g., cold air pooled in the Central Valley and approaching extratropical cyclones), this gap is predisposed to generating westward-directed ageostrophic flows driven by along-gap pressure differences. Two case studies and a five-winter composite analysis of 62 gap-flow cases are presented here to show that flows through the Petaluma Gap significantly impact local distributions of wind, temperature, precipitation, and atmospheric pollutants. These gap flows preferentially occur in pre-cold-frontal conditions, largely because sea level pressure decreases westward along the gap in a stably stratified atmosphere in advance of approaching cold-frontal pressure troughs. Airstreams exiting the Petaluma Gap are only several hundred meters deep and characterized by relatively cold, easterly flow capped by a layer of enhanced static stability and directional vertical wind shear. Airborne air-chemistry observations collected offshore by the NOAA P-3 aircraft illustrate the fact that gap-flow events can transport pollutants from inland to the coast, and that they can contribute to coastally blocked airstreams. The strongest gap-flow cases occur when comparatively deep midtropospheric troughs approach the coast, while the weak cases are tied to anticyclonic conditions aloft. Low-level cold-frontal pressure troughs approaching the coast are stronger and possess a greater along-gap pressure gradient for the strong gap-flow cases. These synoptic characteristics are dynamically consistent with coastal wind profiler observations of stronger low-level gap flow and winds aloft, and greater rainfall, during the strong gap-flow events. However, gap flow, on average, inhibits rainfall at the coast.

Flooding on California's Russian River: Role of atmospheric rivers

Experimental observations collected during meteorological field studies conducted by the National Oceanic and Atmospheric Administration near the Russian River of coastal northern California are combined with SSM/I satellite observations offshore to examine the role of landfalling atmospheric rivers in the creation of flooding. While recent studies have documented the characteristics and importance of narrow regions of strong meridional water vapor transport over the eastern Pacific Ocean (recently referred to as atmospheric rivers), this study describes their impact when they strike the U.S. West Coast. A detailed case study is presented, along with an assessment of all 7 floods on the Russian River since the experimental data were first available in October 1997. In all 7 floods, atmospheric river conditions were present and caused heavy rainfall through orographic precipitation. Not only do atmospheric rivers play a crucial role in the global water budget, they can also lead to heavy coastal rainfall and flooding, and thus represent a key phenomenon linking weather and climate.

Evidence for melt injection in the crust of northern California?

The occurrence of an earthquake sequence near Lake Pillsbury, California during a 6-month period in mid-2000 can be linked to magma transport in the crust; this activity is potentially a pre-cursor to future volcanism. The position of Cenozoic volcanism in the crust of the northern California Coast Ranges is directly linked to the northward migration of the Mendocino triple junction (MTJ) and the formation of a slab window beneath North American crust. The most recent manifestation of this is the Clear Lake volcanics, which began erupting ∼ 2 Ma. With the continued migration of the triple junction, volcanic activity is expected to occur to the north of Clear Lake in the future. These volcanic centers erupt in areas where the crust is undergoing significant modification as a result of slab window processes, and reflect important components in the development of the San Andreas plate boundary system. When precisely relocated, the earthquake sequence defines a streak of seismicity at ∼ 8 km depth. This sequence demonstrates a local time–space migration over a distance of ∼ 10 km in two major pulses of activity in the 6-month time period. Stress modeling allows us to infer that these earthquakes may be the result of several dike injections. In combination with evidence for lower crustal melts in the same region from other seismological studies, we propose that these earthquakes help map the occurrence of melt injection in the mid-crust to depths of ∼ 10 km, and present evidence that MTJ-related melt in the crust of northern California has migrated north of the Clear Lake volcanic center.

Differential Response of Algae on Small Streambed Substrates to Floods

Abstract The effect of floods and base flow on temporal variation in algal biomass on small smooth streambed stones and creviced sand-cases of the caddisfly (Insecta: Trichoptera) Gumaga nigricula was examined in Big Sulphur Creek in coastal Northern California. Replicates of stones and cases were sampled 34 times over a 14 mo period that included nine floods. Stones had ∼2× the algal biomass of cases, based on chlorophyll a concentration. The lower algal biomass on caddisfly cases is consistent with this species' burrowing behavior, which reduces algal biomass by abrasion and light limitation. Algal biomass on stones was reduced by floods and generally increased in the absence of floods. In contrast, neither floods nor extended base flow affected the pattern of algal biomass on caddisfly cases, and biomass on caddisfly cases often exceeded that on stones following floods. Streambed substrates with different textures may provide different degrees of disturbance-protection for benthic microalgae, and rough...

Distribution of bacterial abundance and cell-specific nucleic acid content in the Northeast Pacific Ocean

We tested the idea that bacterial cells with high nucleic acid content (HNA cells) are the active component of marine bacterioplankton assemblages, while bacteria with low nucleic acid content (LNA cells) are inactive, with a large data set (>1700 discrete samples) based on flow cytometric analysis of bacterioplankton in the Northeast Pacific Ocean off the coast of Oregon and northern California, USA. Samples were collected in the upper 150 m of the water column from the coast to 250 km offshore during 14 cruises from March 2001 to September 2003. During this period, a wide range of trophic states was encountered, from dense diatom blooms (chlorophyll- a concentrations up to 43 μg l −1) at shelf stations during upwelling season (March–September) to lower chlorophyll- a concentrations (0.1–5 μg l −1) during winter (November–February) and at basin stations (>1700 m depth). We found only weakly positive relations of log total bacterial abundance to log chlorophyll- a concentration (as a proxy for availability of organic substrate), and of HNA bacteria as a fraction of total bacteria to log chlorophyll- a. Abundance of HNA and LNA bacteria co-varied positively in all regions, although HNA bacteria were more responsive to high phytoplankton biomass in shelf waters than in slope and basin waters. Since LNA cell abundance in general showed responses similar to those of HNA cell abundance to changes in phytoplankton biomass, our data do not support the hypothesis that HNA cells are the sole active component of marine bacterioplankton.

The effect of soil nitrogen on competition between native and exotic perennial grasses from northern coastal California

The invasion of European perennial grasses represents a new threat to the native coastal prairie of northern California. Many coastal prairie sites also experience anthropogenic nitrogen (N) deposition or increased N availability as a result of invasion by N-fixing shrubs. We tested the hypothesis that greater seedling competitive ability and greater responsiveness to high N availability of exotic perennial grasses facilitates their invasion in coastal prairie. We evaluated pairwise competitive responses and effects, and the occurrence of asymmetrical competition, among three common native perennial grasses (Agrostis oregonensis, Festuca rubra, and Nassella pulchra) and three exotic perennial grasses (Holcus lanatus, Phalaris aquatica, and Festuca arundinacea), at two levels of soil N. We also compared the root and shoot biomass and response to fertilization of singly-grown plants, so we could evaluate how performance in competition related to innate plant traits. Competitive effects and responses were negatively correlated and in general varied continuously across native and exotic species. Two exceptions were the exotic species Holcus, which had large effects on neighbors and small responses to them, and competed asymmetrically with all other species in the experiment, and the native grass Nassella, which had strong responses to but little effect on neighbors, and was out-competed by all but one other species in the experiment. High allocation to roots and high early relative growth rate appear to explain Holcus’s competitive dominance, but its shoot biomass when grown alone was not significantly greater than those of the species it out-competed. Competitive dynamics were unaffected by fertilization. Therefore, we conclude that seedling competitive ability alone does not explain the increasing dominance of exotic perennial grasses in California coastal prairie. Furthermore, since native and exotic species responded individualistically, grouping species as ‘natives’ and ‘exotics’ obscured underlying variation within the two categories. Finally, elevated soil N does not appear to influence competition among the native and exotic perennial grasses studied, so reducing soil N pools may not be a critical step for the restoration of California coastal prairie.

A Coupled Upland-Erosion and Instream Hydrodynamic-Sediment Transport Model for Evaluating Sediment Transport in Forested Watersheds

This article describes a prototype modeling system for assessing forest management-related erosion at its source and predicting sediment transport from hillslopes to stream channels and through channel networks to a watershed outlet. We demonstrate that it is possible to develop a land management tool capable of accurately assessing the primary impacts of spatiotemporally varied forest management practices on sediment yield and delivery at hillslope to watershed scales in a single simulation. The modeling system consists of four components: (1) the TOpographic ParameteriZation (TOPAZ) model for discretizing hillslope and channel elements, (2) the Water Erosion Prediction Project (WEPP) model for evaluating hillslope-scale surface erosion processes, (3) the National Center for Computational Hydrodynamics and Engineering's one-dimensional (CCHE1D) hydrodynamic-sediment transport model, and (4) an interface program to manage relational databases and data transfer between modules. The coupled models were calibrated and validated with observed flow and sediment load data from the North Fork Caspar Creek Experimental Watershed in coastal northern California. The coupled models' predictions of peak flow rate and total flow volume were not significantly different from observed values. Predicted sediment concentrations were significantly different from observed values, but within typical ranges for sediment transport equations. We recommend that the WEPP model be improved to allow access to sub-daily time scale results so that it can be better integrated with other watershed models.

Late Neogene and Quaternary landscape evolution of the northern California Coast Ranges: Evidence for Mendocino triple junction tectonics

Late Neogene and Quaternary landscape evolution of the northern California Coast Ranges: Evidence for Mendocino triple junction tectonics

Assessing possible thermal rearing restrictions for juvenile coho salmon (Oncorhynchus kisutch) through thermal infrared imaging and in-stream monitoring, Redwood Creek, California

We quantified patterns in stream temperature in a northern coastal California river using thermal infrared (TIR) imaging and in-stream monitoring and related temperature patterns to the historical and present distributions of juvenile coho salmon (Oncorhynchus kisutch). In Redwood Creek, California, water temperature increased from the headwaters to about 60 km downstream, then gradually decreased over the next 40 km as the river approaches the Pacific Ocean. Despite the lack of fish migration barriers, juvenile coho are currently only observed in the downstream-most 20 km, whereas historically they were found in 90 km of river channel. Maximum daily temperatures and duration of elevated stream temperatures were not significantly different in the headwater and downstream reaches but were significantly higher in the 50 km long intervening reach, where maximum weekly maximum temperatures ranged from 23 to 27 °C. An increase in stream temperatures in the middle basin during the last three decades as a result of channel aggradation, widening, and the removal of large riparian conifers may play an important role in restricting juvenile coho to one-fifth of their historical range.

Effects of invasive scotch broom on soil properties in a Pacific coastal prairie soil

Scotch broom ( Cytisus scoparius) is a leguminous shrub, native to Europe that has invaded significant areas of the Pacific Northwest and rigorously competes with native vegetation. Mineral soils under scotch broom colonies and adjacent coastal prairie on the Mendocino Coast of Northern California were sampled to determine how soil properties and microbial processes have been affected. Soils under scotch broom were significantly more acidic and had greater organic matter content than prairie soils. The activities of two soil enzymes responsible for processing major detrital carbon and phosphorus pools were significantly higher under scotch broom. Organic matter accumulation with no change in C:N, a greater increase in phosphatase activity (123%) than in β-glucosidase (84%) under scotch broom, and a significant difference between soil C:P under scotch broom (619) and prairie vegetation (470) all suggest that the coupling of nutrient cycles has changed.