Humboldt Bay Research Articles

Discovery of Humboldt Bay, California, in 1806 from the Ship O'Cain, Jonathan Winship, Commander

Discovery of Humboldt Bay, California, in 1806 from the Ship O'Cain, Jonathan Winship, Commander

Seasonal Variation in Diurnal and Nocturnal Distributions of Nonbreeding Shorebirds at North Humboldt Bay, California

Recent studies of nocturnal foraging by shorebirds (Charadriiformes: Charadrii) suggest that many species feed at night. Much of this research has been qualitative and/or restricted to a small portion of the annual cycle (e.g., a few nights or one season) making it difficult to evaluate the extent to which nocturnal foraging varies seasonally. Consequently, we examined seasonal variation in abundance and distribution of diurnal and nocturnal foraging shorebirds from 10 Jan 1992-10 Jan 1993 at North Humboldt Bay, California. Shorebirds foraged primarily during the day. Overall, day/night frequency of occurrence (percent of censuses with birds) was 87%/48%. In fall, frequency of occurrence of shorebirds differed less between day and night (day/night: 82%/64%) than during spring (day/night: 79%/14%) or winter (day/night: 100%/42%). Moreover, nocturnal abundance of Marbled Godwit (Limosa fedoa), Willet (Catoptrophorus semipalmatus), dowitchers (Limnodromus scolopaceus and L. griseus), and Black-bellied Plover (Pluvialis squatarola) peaked in fall, whereas diurnal abundance of these species peaked in winter (Marbled Godwit, Black-bellied Plover, and dowitchers) or spring (Willet). Taxa varied in day/night patterns. For Scolopacids, diurnal abundance significantly exceeded nocturnal abundance. However, abundance of American Avocet (Recurvirostra americana), Black-bellied Plover, and Semipalmated Plover (Charadrius semipalmatus) did not differ significantly between day and night. Our results suggest that a researcher's choice of season or taxa may influence observed patterns of diurnal and nocturnal distributions of shorebirds considerably.

Introduction History and Invasion Patterns of Ammophila arenaria on the North Coast of California

European beachgrass (Ammophila arenaria [L] Link), introduced to stabilize sand, is fully naturalized in central and northern California and has supplanted populations of native dune plants in many areas, including the North Spit of Humboldt Bay. We interpreted air photos of the North Spit for the presence of Ammophila arenaria at three points in time: 1939/1942, 1962, and 1989. To quantify the spread and to detect invasion patterns of Ammophila, we then compiled maps using a geographic information system. We documented introduction dates and locations to improve the accuracy of our photo interpretation. Interpretation of the three photo series revealed invasion and expansion of Ammophila in both foredunes and inland dunes. The most dramatic increase in cover was found in the foredunes, whereas documented and presumed plantings were found mostly on inland dunes. Adjusting for intentional eradication, Ammophila cover on the North Spit was found to have increased between 1939 and 1989 by 574%. The square root of the area occupied by Ammophila on the North Spit increased linearly with time, conforming to biological invasion theory.

Waterbird Communities and Habitat Relationships in Coastal Pastures of Northern California

We examined waterbird assemblages (diversity, composition, and species’ densities) in 20 pastures near Humboldt Bay, California, in relation to habitat characteristics (vegetation height, soil penetrability, water depth), abundance of invertebrates (worms and other invertebrates), and presence of livestock. From October 1991 to May 1992 we observed 29 species and 10,776 birds, most (78%) of which foraged. Nonrandom pasture use by birds resulted in a highly clumped spatial distribution (s2:{ovbar>x} ratio = 42.1). Habitat characteristics of pastures correlated with this nonrandom pattern: waterbird diversity and densities of three sandpiper species and one gull species correlated negatively (r = −0.61 and r = −0.44 to −0.67, respectively) with vegetation height; densities of two plover species correlated negatively (r= −0.39 and −0.45) with soil penetrability; and waterfowl densities correlated positively with water depth (r = 0.97). Species composition varied among pastures. Wading birds used pastures with tall vegetation, shorebirds and gulls frequented short‐grass pastures, and waterfowl used flooded pastures of waterbirds and their densities increased in association with livestock.In coastal areas where much intertidal habitat has been reclaimed as postureland, pastures offered valuable habitats to nonbreeding waterbirds. We suggest that grazing in coastal pastures can be used to provide a mosaic of vegetation heights, which would yield greater waterbird diversity as well as higher densities of some species.

Trees and herbs killed by an earthquake ∼300 yr ago at Humboldt Bay, California

Research Article| January 01, 1995 Trees and herbs killed by an earthquake ∼300 yr ago at Humboldt Bay, California Gordon Jacoby; Gordon Jacoby 1Lamont-Doherty Earth Observatory, Palisades, New York 10964 Search for other works by this author on: GSW Google Scholar Gary Carver; Gary Carver 2Department of Geology, Humboldt State University, Arcata, California 95521 Search for other works by this author on: GSW Google Scholar Wendy Wagner Wendy Wagner 1Lamont-Doherty Earth Observatory, Palisades, New York 10964 Search for other works by this author on: GSW Google Scholar Author and Article Information Gordon Jacoby 1Lamont-Doherty Earth Observatory, Palisades, New York 10964 Gary Carver 2Department of Geology, Humboldt State University, Arcata, California 95521 Wendy Wagner 1Lamont-Doherty Earth Observatory, Palisades, New York 10964 Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1995) 23 (1): 77–80. https://doi.org/10.1130/0091-7613(1995)023<0077:TAHKBA>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Gordon Jacoby, Gary Carver, Wendy Wagner; Trees and herbs killed by an earthquake ∼300 yr ago at Humboldt Bay, California. Geology 1995;; 23 (1): 77–80. doi: https://doi.org/10.1130/0091-7613(1995)023<0077:TAHKBA>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Evidence of rapid seismic-induced subsidence at Humboldt Bay, California, is produced by analyses of annual growth rings of relict Sitka spruce [Picea sitchensis (Bong.) Carr.] roots and entombed herbaceous plants. These results add to previously reported evidence that an earthquake caused subsidence ∼300 yr ago at Mad River slough, California. Both types of remains are rooted in buried soils that stood at or above the high-tide level until the area subsided at least 0.5 m into the intertidal zone. Burial by intertidal muds took place quickly enough to preserve the herbs in the growth position. Analysis of the annual growth rings of the tree roots shows that all died within four growing seasons, but the time of root death varies even among roots of the same tree. With no central nervous system, tree cells do not die simultaneously throughout the organism. The 0.5 to 1.5 m of subsidence, as evidenced by stratigraphy and sedimentology, was not enough to kill all the trees even in one season. Although such gradual death could be due to rapid aseismic subsidence, the tree deaths and preserved herbs are much better explained by sudden coseismic subsidence. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Art of Northwest New Guinea: From Geelvink Bay, Humboldt Bay and Lake Sentani.

Art of Northwest New Guinea: From Geelvink Bay, Humboldt Bay and Lake Sentani.

Correction: Status and Habitat Use by American Avocets Wintering at Humboldt Bay, California

Correction: Status and Habitat Use by American Avocets Wintering at Humboldt Bay, California

Status and Habitat Use by American Avocets Wintering at Humboldt Bay, California

The wintering avocet (Recurvirostra americana) population at Humboldt Bay, California averaged 706 ± 35.6 (n = 30) and 567 ± 67.0 (n = 30) birds from October to May, 1982-1983 and 1983-1984 respectively. Avocets arrived from late-August to mid-November. Birds departed from February to late-April and early-May. Avocets are recorded only casually at other northern California coastal sites. After construction of sewage oxidation ponds at the northeast corner of North Humboldt Bay in 1957, the number of avocets wintering at Humboldt Bay increased. The present wintering population of avocets at Humboldt Bay has increased from 30-35 in 1960 to 500-800 at present. Humboldt Bay probably has the capability to support a larger wintering population than presently exists. Avocets used 868 ha in the northeast corner of North Humboldt Bay, California. Within this area, which covered approximately 25% of available habitat in North Bay, the four major habitats used were: (1) intertidal mud flats, used mainly for feeding and resting; (2) a sewage oxidation pond, used mainly for feeding and secondarily, as a source of fresh water; (3) a section of the North Bay's highest elevation mud flats, used as an early high tide roost; and (4) islands in a brackish 6.9 ha lake adjacent to the North Bay, used as the primary high tide roost. Avocets typically roosted on shallow, submerged bars of islands in deep non-tidal ponds or in shallow water or exposed mud near the water's edge of tidal mud flats. Islands adjacent to deep, non-tidal ponds were used most frequently as roosting sites. Avocets fed at the oxidation ponds mainly in October when high concentrations of invertebrate prey, especially Daphne magna, were present. All other foraging took place on intertidal mud flats within 3 km of roosts. Avocets primarily fed using tactile methods in the wettest substrates. They usually fed within 100 m of the tide edge, and most foraging took place when tide levels were between 0.5 and 1.2 m Mean Lower Low Water (MLLW).

Review: Saving California's Coast: Army Engineers at Oceanside and Humboldt Bay, by Susan Pritchard O'Hara and Gregory Graves

Review: <i>Saving California's Coast: Army Engineers at Oceanside and Humboldt Bay</i>, by Susan Pritchard O'Hara and Gregory Graves

The ecology of Humboldt Bay, California, an estuarine profile: R. A. Barnhart, M. J. Boyd & J. E. Pequegnat, Biological Report - US Fish & Wildlife Service, 1, 1992, 121 pp

The ecology of Humboldt Bay, California, an estuarine profile: R. A. Barnhart, M. J. Boyd & J. E. Pequegnat, Biological Report - US Fish & Wildlife Service, 1, 1992, 121 pp

Early Use by Fish of a Mitigation Salt Marsh, Humboldt Bay, California

Fish numbers and biomass in a mitigation salt marsh, Humboldt Bay, California, were examined from July 1981 to October 1982 and were compared with a nearby established marsh to determine whether the restored marsh provided adequate mitigation for habitat lost due to construction of a nearby marina. The use by fish of channels adjacent to the two marshes and the channel at the Woodley Island Marina construction site, for which mitigation was required, were also compared. The mitigation marsh, adjacent to Freshwater Slough channel, was 5.2 km from the marina site. Fishes were sampled by otter trawl, ichthyoplankton net, fixed channel nets, drop traps, and beach seines. Thirty-one fish species and two crab species were collected. Wide ranges in seasonal salinities and water temperatures, and differences in marsh elevation influenced fish use of the mitigation marsh area. The intertidal area of the mitigation marsh, dominated by euryhaline sticklebacks and topsmelts, did not replace intertidal and subtidal habitat lost by marina construction, which had more stable salinities and water temperatures and was used extensively by juvenile English sole.

Review: SAVING CALIFORNIA'S COAST: Army Engineers at Oceanside and Humboldt Bay, by Susan Pritchard O'Hara and Gregory Graves

Review: <i>SAVING CALIFORNIA'S COAST: Army Engineers at Oceanside and Humboldt Bay</i>, by Susan Pritchard O'Hara and Gregory Graves

Seismicity of the Gorda Plate, structure of the continental margin, and an eastward jump of the Mendocino Triple Junction

Analysis of 9 years of data from the Humboldt Bay seismic network sheds new light on the structure and evolution of the Gorda plate and Mendocino triple junction. Significant findings include the buttressing effect of the Pacific plate which demonstrates that there is no underthrusting of the Gorda plate along the Mendocino fault, and the pattern of left‐lateral northeast‐trending faults, which demonstrates how the Gorda plate accommodates N‐S shortening without such underthrusting. Focal mechanisms are consistent with northward compression of the Gorda plate by the Pacific plate until the Gorda plate passes the triple junction, beyond which the N‐S compressive stress is effectively removed, and the focal mechanisms show a change from strike slip to normal faulting with downslab tension. Another significant feature is the shallow Benioff zone (10–40 km) which shows a double seismogenic layer. Unlike most other double seismic layers in deep subduction zones, this one appears to be due to underplating, with a new subduction zone being developed east of the former one. A corner of continental margin material has been partially subducted. We attribute this double seismic zone to reactivation of both the old and new subduction boundaries under N‐S compression produced by Pacific‐Gorda plate interaction at the triple junction. Because the geometry of this triple junction indicates that it is unstable and because there is evidence that as part of its evolution the San Andreas fault has migrated eastward, we have constructed a model that accounts for both the eastward migration of the San Andreas fault and the doubling of the seismic zone in the Gorda plate. This can be done by assuming that at the time of the last eastward jump of the fault, the overriding continental margin north of the triple junction was broken and underthrust producing a new subduction zone that is collinear with the San Andreas fault. Other scenarios for the evolution of the Mendocino triple junction do not require that the subduction zone migrate eastward. However, the position and dip of the double zone indicate that an eastward jump of 100 km some 5 my ago could have taken place. This is consistent with other evidence for an eastward jump of the San Andreas fault.

Saving California's Coast: Army Engineers at Oceanside and Humboldt Bay

Saving California's Coast: Army Engineers at Oceanside and Humboldt Bay

Late Holocene Tectonics and Paleoseismicity, Southern Cascadia Subduction Zone

Holocene deformation indicative of large subduction-zone earthquakes has occurred on two large thrust fault systems in the Humboldt Bay region of northern California. Displaced stratigraphic markers record three offsets of 5 to 7 meters each on the Little Salmon fault during the past 1700 years. Smaller and less frequent Holocene displacements have occurred in the Mad River fault zone. Elsewhere, as many as five episodes of sudden subsidence of marsh peats and fossil forests and uplift of marine terraces are recorded. Carbon-14 dates suggest that the faulting, subsidence, and uplift events were synchronous. Relations between magnitude and various fault-offset parameters indicate that earthquakes accompanying displacements on the Little Salmon fault had magnitudes of at least 7.6 to 7.8. More likely this faulting accompanied rupture of the boundary between the Gorda and North American plates, and magnitudes were about 8.4 or greater.

Irregular geometry of the Gorda subduction and deep structure of the Eel River basin determined from teleseismic P delays

Nearly 1000 observations of travel-time residuals for teleseismic P arrivals across the Humboldt Bay Seismic Network near Cape Mendocino, California, are analyzed for a study of 3-D geometry of the Gorda plate near Mendocino Triple Junction (MTJ), by the application of a three-dimensional velocity inversion procedure. The area is underlain by the subducted edge of the Gorda plate and the eastward extension of the Mendocino Fracture Zone. The observed variation of the travel-time gradient with azimuth favors either deepening of the slab southward, or southward increase of dilatational velocity across the Mendocino Fracture Zone at depths of more than 50 km. The topographically corrected mean travel-time delays at individual stations suggest that the Eel River basin is deep and tectonically controlled. Further support for this view is provided by the inversion results, which point to the possible extension of the low-velocity material through the entire crustal section. These results also suggest that from the south, the Eel River basin may be confined at depth by a steeply northward-dipping sliver of high-velocity material (possibly a detached oceanic slab). This feature may be responsible for the intense seismic activity reported beneath the eastern end of the Mendocino Fracture Zone (MFZ). Thus, the role of the Eel River basin in accommodating the relative motion between the adjacent plates, may be significant. The leading edge of the downgoing slab appears irregular and at some latitudes may not extend beyond the coast line. The estimated velocity anomalies vary by as much as 20% in the near-surface blocks and nearly half as much at depth. The pattern may result from intense tearing and deformation of the slab, producing buckling, folding and compression ridges.

Haematozoa of Fishes in Humboldt Bay, California

Five hundred seven fish representing 45 species from Humboldt Bay, California (USA) were examined for blood parasites. Four fish (less than 1%) from two species were infected. Haemogregarina leptocotti sp. n. is described from one of 33 staghorn sculpin (Leptocottus armatus). Haemogregarina roelofsi sp. n. is described from three of 15 black rockfish (Sebastes melanops). Gametocytes of H. leptocotti sp. n. averaged 6.1 x 2.1 microns with a 2.7 x 1.7 microns oval nucleus; those of H. roelofsi sp. n. averaged 5.5 x 2.7 microns with a 2.5 x 2.2 microns rectangular nucleus. Neither species of parasite had distinct chromatin granules, a polar cap, or more than one gametocyte in an infected cell. Haematozoa are relatively rare in fishes of the northeastern Pacific Ocean.

UTILITIES AND DECOMMISSIONING COSTS: THE MEETING OF TECHNOLOGY AND SOCIETY

Nuclear energy policy is impacted by several groups, including regulatory agencies, public interest organizations, private business, and academic research. As policy bends and changes, no group is affected more strongly than public utility companies. The principal reason for such sensitivity is that the utility companies, more than any of the other players in the decommissioning business, are the link between technology and society. This chapter presents the utility view of decommissioning within the context of PG&amp;E’s nuclear power stations at Diablo Canyon and Humboldt Bay. The discussion includes special utility problems, such as inherent uncertainties and the causes for over- and underestimating. Among the conclusions is that the overall discussion of decommissioning technology is developing outside the commercial marketplace and will likely lead to inefficiencies, and that the various social costs and ramifications of decommissioning need much more attention.

Genetic drift and effective population sizes of hatchery-propagated stocks of the Pacific oyster, Crassostrea gigas

Using starch-gel electrophoresis, we scored genetic differences for 14 polymorphic enzymes among individuals from three Pacific oyster populations: natural set from Dabob Bay, Washington, and two cultivated stocks. The stocks were each derived from the Dabob Bay wild population and reproductively isolated from this population and from each other for three generations via hatchery propagation and separate rearing on commercial growout beds in Willapa Bay, Washington, and Humboldt Bay, California. Compared with the wild population, one of the two cultivated stocks had significantly fewer alleles per locus, but proportions of polymorphic loci and average heterozygosities were not statistically different among the three population samples. Hatchery-propagated stocks differed markedly in allelic frequencies from each other and from the wild population at most loci. Allelic frequencies in the Dabob Bay sample are assumed to represent those in the progenitors of the hatchery stocks. Average per locus allele-frequency variances between the progenitor and derived hatchery populations are normally distributed after appropriate transformation, indicating that divergence of hatchery stocks from Dabob Bay population owes to random genetic drift. Based on the inverse relationship between the magnitude of random genetic drift and effective population size ( N e), the per-generation effective sizes of the two commercial oyster stocks are calculated to be only 40.6±13.9 (s.d.) and 8.9±2.2 (s.d.) for the Willapa Bay and Humboldt Bay stocks, respectively. These estimates account well for the loss of alleles in these hatchery-propagated stocks. Analysis of allele-frequency drift is recommended over simple comparisons of genetic diversity for revealing the extent and nature of genetic change in reproductively isolated aquaculture stocks.

Distribution of the Marbled Murrelet at Inland Sites in California

We conducted transect surveys from the Oregon border to Monterey County in 1988 and 1989 to determine the distribution of marbled murrelets (Brachyram- phus marmoratus) at inland sites in California. This seabird uses the coastal redwood (Sequoia sempervirens) forests of the northern half of California, but little is known of its distribution away from the ocean. We identified potential inland habitat from remote sensing data and then conducted systematic surveys of forest stands based on this inventory. Murrelets were detected on 74 of 170 (44%) transects, with a patchy distribution concentrated in three regions in Del Norte, Humboldt, San Mateo, and Santa Cruz Counties: (1) east of Crescent City to Redwood Creek in Redwood National Park; (2) lands east of Humboldt Bay to Humboldt Redwoods State Park on the Eel River; and (3) state parks in southern San Mateo and northern Santa Cruz Counties. The primary habitat type where birds were detected was old-growth dominated forest, with 1.05 detections/station, compared to 0.02 detections/station on second-growth transects. Transects with high activity levels tended to be in or west of old-growth stands ~250 ha. The farthest inland we observed murrelets was 39 km from the coast.