Articles

Published journal articles by MLML faculty, staff and students. Full text is included when copyright allows.


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State of the California Current 2006-2007: Regional and local processes dominate
State of the California Current 2006-2007: Regional and local processes dominate
The state of the California Current System (CCS) between Oregon and Baja California is summarized in this report, covering spring 2006 to spring 2007. Observations reported here are based on contributions from various ocean observing programs along the West Coast of North America. Basin-scale indicators were variable or neutral over the last year. This indeterminate forcing was reflected in conditions in the CCS where no coherent patterns emerged, i.e., no single “state” could be ascribed to the system. Rather, regional or local processes dominated observed patterns. Similar to last year, delayed upwelling off Oregon and central California dramatically affected higher trophic levels: euphausiid recruitment was delayed and as a likely consequence seabird productivity off Central California was extremely depressed. For example, Cassin’s auklet had a complete reproductive failure, similar to 2006. Observations during the spring of 2007 demonstrate that these patterns were ephemeral since upwelling was normal and seabird productivity improved. Off southern and Baja California, upwelling-favorable winds were also weak or delayed during 2006, but biological consequences appear to have been relatively minor., Downloaded from: calcofi.org/publications/.../v48/Vol_48_State_Of_California_Current.pdf (2 July 2014).
Statistical significance of sediment toxicity test results: Threshold values derived by the detectable significance approach
Statistical significance of sediment toxicity test results: Threshold values derived by the detectable significance approach
A number of methods have been employed to determine the statistical significance of sediment toxicity test results. To allow consistency among comparisons, regardless of among-replicate variability, a protocol-specific approach has been used that considers protocol performance over a large number of comparisons. Ninetieth-percentile minimum significant difference (MSD) values were calculated to determine a critical threshold for statistically significant sample toxicity. Significant toxicity threshold values (as a percentage of laboratory control values) are presented for six species and nine endpoints based on data from as many as 720 stations. These threshold values are useful for interpreting sediment toxicity data from large studies and in eliminating cases where statistical significance is assigned in individual cases because among-replicate variability is small.
Status of the California sea cucumber (Parastichopus californicus) and red sea urchin (Mesocentrotus franciscanus) commercial dive fisheries in the San Juan Islands, Washington State, USA
Status of the California sea cucumber (Parastichopus californicus) and red sea urchin (Mesocentrotus franciscanus) commercial dive fisheries in the San Juan Islands, Washington State, USA
The San Juan Archipelago is the most intensely fished region of Washington State for echinoderms. Commercial dive fisheries for both the California sea cucumber (Parastichopus californicus) and red sea urchin (Mesocentrotus franciscanus) were characterized by high levels of harvest in the late 1980s and early 1990s. Here we evaluate stock performance of both species under the current fishery management regime using biomass estimates from a remotely-operated vehicle survey, time series of relative abundance from SCUBA index station surveys, and harvester log book data. We also report habitat associations of both species with depth and seafloor substrate composition. The fully-utilized quota for Parastichopus represents an 11.4% annual harvest rate on the current harvestable biomass estimate, and signs that this rate is unsustainable include: low density in shallow waters, a relative abundance that has remained depressed, and a continuous decline in catch-per-unit-effort (CPUE). Abundant Parastichopus below harvestable depths may not be of sufficient density to act as a consistent reservoir to replenish the shallows with recruits. The partially-utilized quota for Mesocentrotus represents a 3.9% annual harvest rate on the current biomass estimate, relative abundance has increased from a recent low, and there is no trend in CPUE. Numerous similarities between the two fisheries with regard to fleet composition and harvest history, coupled with diverging stock status, suggest that the sea cucumber fishery may be slower to recover from over-exploitation. Despite the challenges of co-managing the fisheries among several stakeholder groups, agreement has been reached to improve the long term viability of the Parastichopus fishery using reduced harvest quotas and a closure during peak spawning months, and to continue to closely monitor the Mesocentrotus fishery.
Strategies and rates of photoacclimation in two major Southern Ocean phytoplankton taxa: Phaeocystis antarctica (Haptophyta) and Fragilariopsis cylindrus (Bacillariophyceae)
Strategies and rates of photoacclimation in two major Southern Ocean phytoplankton taxa: Phaeocystis antarctica (Haptophyta) and Fragilariopsis cylindrus (Bacillariophyceae)
We investigated rates and mechanisms of photoacclimation in cultures of Phaeocystis antarctica G. Karst. and Fragilariopsis cylindrus (Grunow) Willi Krieg, phytoplankton taxa that each dominate distinct areas of the Ross Sea, Antarctica. Both P. antarctica and F. cylindrus acclimated to increases in irradiance by reducing the effective size of the pigment antenna (σPSII) via xanthophyll-cycle activity and reductions in chl. While enhanced photoprotection facilitated increases in specific growth rate and eventually led to higher light-saturated photosynthetic rates (P cell m) in P. antarctica, increases in those variables were much smaller in F. cylindrus. In response to a lower irradiance, relaxation of xanthophyll-cycle activity led to an increase in σPSII in both taxa, which occurred much more slowly in F. cylindrus. A surprising increase in specific growth rate over the first 36 h of acclimation in P. antarctica may have facilitated the significant reductions in P cell m observed in that taxon. In general, P. antarctica acclimated more quickly to changes in irradiance than F. cylindrus, exhibited a wider range in photosynthetic rates, but was more susceptible to photoinhibition. This acclimation strategy is consistent with growth in deeply mixed water columns with variations in irradiance that allow time for repair. In contrast, the slower acclimation rates, extensive photoprotection, and low photoinhibition exhibited by F. cylindrus suggest that it does not require the same period for repair as P. antarctica and is best suited for growth in habitats with relatively uniform irradiance, such as shallow mixed layers or sea ice. © 2010 Phycological Society of America., Cited By (since 1996):14, Oceanography, CODEN: JPYLA
Stratigraphy of late Quaternary estuarine deposits and amino acid stereochemistry of oyster shells beneath San Francisco Bay, California
Stratigraphy of late Quaternary estuarine deposits and amino acid stereochemistry of oyster shells beneath San Francisco Bay, California
The sequence of Quaternary deposits beneath the floor of San Francisco Bay includes four to seven noncontemporaneous estuarine units intercalated with alluvium and dune sand. Units L (0-10,000 B.P.), M (>40,000 B.P., probably ca. 80,000-140,000 B.P.), and N (older than unit M) are distinctly superposed. The dominant molluscan fossil in each of these three units is Ostrea lurida Carpenter, the native oyster along much of the pacific Coast of North America. Despite a lamellar structure that suggests vulnerability to contamination, O. lurida shells generally yield amino acid enantiomeric ratios that are analytically reproducible and stratigraphically consistent. The kinetics of racemization in O. lurida conceivably resembles that of Protothaca and Saxidomus, other bivalves whose kinetics of racemization are relatively well understood. Assuming such a resemblance, enantiomeric ratios in O. lurida imply that (1) unit M is the same approximate age as estuarine terrace deposits bordering San Pablo Bay and Carquinez Strait, providing that the terrace deposits have been at diagenetic temperatures 1°-2°C warmer than unit M; and (2) the age of unit N is about four times greater than that of unit M, providing that both units have been at the same approximate diagenetic temperature. © 1981., Cited By (since 1996):4, Rocks and Cores
Stray light correction algorithm for multichannel hyperspectral spectrographs
Stray light correction algorithm for multichannel hyperspectral spectrographs
An algorithm is presented that corrects a multichannel fiber-coupled spectrograph for stray or scattered light within the system. The efficacy of the algorithm is evaluated based on a series of validation measurements of sources with different spectral distributions. This is the first application of a scattered-light correction algorithm to a multichannel hyperspectral spectrograph. The algorithm, based on characterization measurements using a tunable laser system, can be extended to correct for finite point-spread response in imaging systems. © 2012 Optical Society of America., Cited By (since 1996):1, Oceanography, CODEN: APOPA
Stray light correction of the marine optical system
Stray light correction of the marine optical system
The Marine Optical System is a spectrograph-based sensor used on the Marine Optical Buoy for the vicarious calibration of ocean color satellite sensors. It is also deployed from ships in instruments used to develop bio-optical algorithms that relate the optical properties of the ocean to its biological content. In this work, an algorithm is applied to correct the response of the Marine Optical System for scattered, or improperly imaged, light in the system. The algorithm, based on the measured response of the system to a series of monochromatic excitation sources, reduces the effects of scattered light on the measured source by one to two orders of magnitude. Implications for the vicarious calibration of satellite ocean color sensors and the development of bio-optical algorithms are described. The algorithm is a one-dimensional point spread correction algorithm, generally applicable to nonimaging sensors, but can in principle be extended to higher dimensions for imaging systems. © 2009 American Meteorological Society., Cited By (since 1996):6, Oceanography, CODEN: JAOTE, Downloaded from: journals.ametsoc.org/doi/pdf/10.../2008JTECHO597.1 (16 June 2014).
Stray-light correction algorithm for spectrographs
Stray-light correction algorithm for spectrographs
In this paper, we describe an algorithm to correct a spectrograph's response for stray light. Two recursion relations are developed: one to correct the system response when measuring broad-band calibration sources, and a second to correct the response when measuring sources of unknown radiance. The algorithm requires a detailed understanding of the effect of stray light in the spectrograph on the instrument's response. Using tunable laser sources, a dual spectrograph instrument designed to measure the up-welling radiance in the ocean was characterized for stray light. A stray-light correction algorithm was developed, based on the results of these measurements. The instrument's response was corrected for stray light, and the effects on measured up-welling in-water radiance were evaluated., Cited By (since 1996):27, Oceanography, CODEN: MTRGA
Structural control of fluid flow: Offshore fluid seepage in the Santa Barbara Basin, California
Structural control of fluid flow: Offshore fluid seepage in the Santa Barbara Basin, California
Evidence of active and dormant fluid seepage in the Santa Barbara Basin is observed as active venting of gas and oil, bacterial mats, precipitates of authigenic carbonate, and mud and tar volcanoes. Fluid seepage occurs preferentially in the proximity to faults and faulted anticlines, and to slump scarps. Seepage next to faults and anticlines indicates that hydrocarbon migration and pore fluid expulsion is controlled structurally, with faults acting as preferred conduits for fluid flow across units of low matrix permeability. (C) 2000 Elsevier Science B.V. All rights reserved., Cited By (since 1996):38, Oceanography, CODEN: JGCEA
Structure of the Alaskan Gyre in August 2014
Structure of the Alaskan Gyre in August 2014
Hydrographic data (CTD casts to 500 dbar, shipboard ADCP) were collected between Dutch Harbor, Alaska, and Trinidad Head, California, from 28 July to 8 August, 2014, on R/V Point Sur. The section crossed the Alaska Gyre as well as the transition zone between the subpolar and subtropical gyres along the West Coast of the United States. Near surface, freshest waters (S<31.5) were found on either end of the section, marking the flow of the Alaska Stream at the western boundary and fresh waters associated with North American rivers near the eastern boundary. The westward flow of the Alaska Stream was confined to the western 500 km of the section. Immediately to the east of the Stream, stratification changed little for the next 500 km before isopycals sloped downward to the east over the next 1000 km (to depths near those observed at the western boundary) marking westward and northward flow around the Alaskan Gyre. The transition zone was marked by a pycnostad between 26.4 and 26.8 kg/m3 as well as by a sharp front at the eastern edge of the nearsurface salinity minimum and an associated mesoscale anticyclonic anomaly which extended throughout the observed 500 m water column. At the eastern boundary, flow patterns were resolved from surface to bottom (~3000 m) using both CTD and LADCP measurements. The observed pattern of flow was complex although coastal upwelling and poleward flow of California Undercurrent waters over the upper portion of the continental slope occurred. Oxygen, transmissivity and fluorescence patterns are also discussed. Nearsurface current and salinity patterns are compared with satellite measurements.
Study on Conservation Priorities for Shark and Ray Species included and proposed for inclusion in Annex 1 to the CMS Memorandum of Understanding on the Conservation of Migratory Sharks
Study on Conservation Priorities for Shark and Ray Species included and proposed for inclusion in Annex 1 to the CMS Memorandum of Understanding on the Conservation of Migratory Sharks
The Convention on the Conservation of Migratory Species of Wild Animals (UNEP/CMS) currently lists 29 elasmobranch species (13 sharks and 16 rays) on its Appendices I and/or II, with Appendix I requesting the full protection of species and II the development of a specialized (“regional”) agreement to foster cooperation of all Range States to conserve the listed species. All species of sharks and rays are included in Appendix II, which means that these species would benefit from international cooperation, and 19 species are additionally included in Annex 1 of the Convention. In 2010 a specialized agreement as foreseen for Appendix II listed species was concluded for migratory sharks. This Memorandum of Understanding for migratory Sharks (Sharks MOU) already includes seven species in Annex 1.
Sub-mesoscale coastal eddies observed by high frequency radar: A new mechanism for delivering nutrients to kelp forests in the Southern California Bight
Sub-mesoscale coastal eddies observed by high frequency radar: A new mechanism for delivering nutrients to kelp forests in the Southern California Bight
Sub-mesoscale eddies are described along the mainland coast of the Santa Barbara Channel based on observations from a network of high frequency (HF), current-measuring radars and near-shore moorings. The eddies are 4-15 km in diameter and typically last about 2 days, although some last up to 6 days. Most eddies within the radar coverage area are anti-cyclonic with relative vorticities of -0.4 f to -0.8 f where f is the Coriolis parameter, but cyclonic eddies are also observed. Moored observations over the inner shelf (12 m water depth) of a sequence of two eddies in December 2001 show an increase in nitrate plus nitrite from the background levels of 1-2 μM to a maximum of 10-12 μM when the eddies are present. We speculate that these eddies are an important transport mechanism for nutrients and biogenic particles to inner shelf ecosystems of the Southern California Bight. Copyright 2005 by the American Geophysical Union., Cited By (since 1996):30, Oceanography, CODEN: GPRLA, Downloaded from: http://onlinelibrary.wiley.com/doi/10.1029/2005GL023017/pdf (14 June 2014).
Sub-tidal benthic habitats of central San Francisco Bay and offshore Golden Gate area - A review
Sub-tidal benthic habitats of central San Francisco Bay and offshore Golden Gate area - A review
Deep-water potential estuarine and marine benthic habitat types were defined from a variety of new and interpreted data sets in central San Francisco Bay and offshore Golden Gate area including multibeam echosounder (MBES), side-scan sonar and bottom grab samples. Potential estuarine benthic habitats identified for the first time range from hard bedrock outcrops on island and mainland flanks and some Bay floor regions, to soft, very dynamic bedforms consisting of sediment waves and ripples. Soft sediment ranges from mud and sand to bimodal (two or more grain sizes) sediment of gravel, pebbles, and cobbles. In addition, considerable anthropogenic features (i.e., pipelines, bridge abutments, dredged channels, dump sites) were distinguished. Of the 52 potential benthic habitat types mapped (compressed to 14 types for this paper), 24 were of unconsolidated sediment with five of these comprised of dynamic bedforms or sediment waves and dunes, five of mixed (soft over hard) substrate type, six of hard substrate or rock outcrop, 13 of anthropogenically disturbed areas and four hard anthropogenic features. Rock outcrops and rubble are considered the primary habitat type for rockfish (Sebastes spp.), lingcod (Ophiodon elongatus) and in shallow water for herring (Clupea pallasii) spawning. Dynamic bedforms such as sand waves are considered potential foraging habitat for juvenile lingcod, may be sub-tidal habitat for the Pacific sand lance (Ammodytes hexapterus) forage fish, and possibly resting habitat for migratory fishes such as sturgeon (Acipenser medirostris). The potential marine benthic habitats identified in San Francisco Bay are not unlike those found in other estuaries around the world and this study should contribute significant information that will be of interest to scientists, managers and fishers investigating and utilizing bay and estuarine resources. As described in the many papers of this special issue, the understanding of the interrelationship of geology and ecology is critical to the identification of essential habitats and the sustainability of a healthy ecosystem. © 2013 The Authors., Ecology, Rocks and Cores, Article in Press, CODEN: MAGEA
Submarine Groundwater Discharge-Derived Nutrient Loads to San Francisco Bay: Implications to Future Ecosystem Changes
Submarine Groundwater Discharge-Derived Nutrient Loads to San Francisco Bay: Implications to Future Ecosystem Changes
Submarine groundwater discharge (SGD) was quantified at select sites in San Francisco Bay (SFB) from radium (223Ra and 224Ra) and radon (222Rn) activities measured in groundwater and surface water using simple mass balance box models. Based on these models, discharge rates in South and Central Bays were 0.3–7.4 m3 day−1 m−1. Although SGD fluxes at the two regions (Central and South Bays) of SFB were of the same order of magnitude, the dissolved inorganic nitrogen (DIN) species associated with SGD were different. In the South Bay, ammonium (NH 4 + ) concentrations in groundwater were three-fold higher than in open bay waters, and NH 4 + was the primary DIN form discharged by SGD. At the Central Bay site, the primary DIN form in groundwater and associated discharge was nitrate (NO 3 − ). The stable isotope signatures (δ15NNO3 and δ18ONO3) of NO 3 − in the South Bay groundwater and surface waters were both consistent with NO 3 − derived from NH 4 + that was isotopically enriched in 15N by NH 4 + volatilization. Based on the calculated SGD fluxes and groundwater nutrient concentrations, nutrient fluxes associated with SGD can account for up to 16 % of DIN and 22 % of DIP in South and Central Bays. The form of DIN contributed to surface waters from SGD may impact the ratio of NO 3 − to NH 4 + available to phytoplankton with implications to bay productivity, phytoplankton species distribution, and nutrient uptake rates. This assessment of nutrient delivery via groundwater discharge in SFB may provide vital information for future bay ecological wellbeing and sensitivity to future environmental stressors.
Submarine landslides in the Santa Barbara Channel as potential tsunami sources
Submarine landslides in the Santa Barbara Channel as potential tsunami sources
Recent investigations using the Monterey Bay Aquarium Research Institutes (MBARI) Remotely Operated Vehicles (ROVs) "Ventana" and "Tiburon" and interpretation of MBARI's EM 300 30 kHz multibeam bathymetric data show that the northern flank of the Santa Barbara Basin has experienced massive slope failures. Of particular concern is the large (130 km2) Goleta landslide complex located off Coal Oil Point near the town of Goleta, that measures 14.6-km long extending from a depth of 90 m to nearly 574 m deep and is 10.5 km wide. We estimate that approximately 1.75 km3 has been displaced by this slide during the Holocene. This feature is a complex compound submarine landslide that contains both surfical slump blocks and mud flows in three distinct segments. Each segment is composed of a distinct head scarp, down-dropped head block and a slide debris lobe. The debris lobes exhibit hummocky topography in the central areas that appear to result from compression during down slope movement. The toes of the western and eastern lobes are well defined in the multibeam image, whereas the toe of the central lobe is less distinct. Continuous seismic reflection profiles show that many buried slide debris lobes exist and comparison of the deformed reflectors with ODP Drill Site 149, Hole 893 suggest that at least 200 000 years of failure have occurred in the area (Fisher et al., 2005a). Based on our interpretation of the multibeam bathymetry and seismic reflection profiles we modeled the potential tsunami that may have been produced from one of the three surfical lobes of the Goleta slide. This model shows that a 10 m high wave could have run ashore along the cliffs of the Goleta shoreline. Several other smaller (2 km2 and 4 km2) slides are located on the northern flank of the Santa Barbara Basin, both to the west and east of Goleta slide and on the Concepcion fan along the western flank of the basin. One slide, named the Gaviota slide, is 3.8 km2, 2.6 km long and 1.7 km wide. A distinct narrow scar extends from near the eastern head wall of this slide for over 2 km eastward toward the Goleta slide and may represent either an incipient failure or a remnant of a previous failure. Push cores collected within the main head scar of this slide consisted of hydrogen sulfide bearing mud, possibly suggesting active fluid seepage and a vibra-core penetrated ∼50 cm of recent sediment overlying colluvium or landslide debris confirming the age of ∼300 years as proposed by Lee et al. (2004). However, no seeps or indications of recent movement were observed during our ROV investigation within this narrow head scar indicating that seafloor in the scar is draped with mud. © 2006 Author(s). This work is licensed under a Creative Commons License., Cited By (since 1996):19, Oceanography, Downloaded from: www.nat-hazards-earth-syst-sci.net/6/63/2006/nhess-6-63-2006.pdf (16 June 2014).
Submarine landslides of the Southern California Borderland
Submarine landslides of the Southern California Borderland
Conventional bathymetry, sidescan-sonar and seismic-reflection data, and recent, multibeam surveys of large parts of the Southern California Borderland disclose the presence of numerous submarine landslides. Most of these features are fairly small, with lateral dimensions less than ̃2 km. In areas where multibeam surveys are available, only two large landslide complexes were identified on the mainland slope- Goleta slide in Santa Barbara Channel and Palos Verdes debris avalanche on the San Pedro Escarpment south of Palos Verdes Peninsula. Both of these complexes indicate repeated recurrences of catastrophic slope failure. Recurrence intervals are not well constrained but appear to be in the range of 7500 years for the Goleta slide. The most recent major activity of the Palos Verdes debris avalanche occurred roughly 7500 years ago. A small failure deposit in Santa Barbara Channel, the Gaviota mudflow, was perhaps caused by an 1812 earthquake. Most landslides in this region are probably triggered by earthquakes, although the larger failures were likely conditioned by other factors, such as oversteepening, development of shelf-edge deltas, and high fluid pressures. If a subsequent future landslide were to occur in the area of these large landslide complexes, a tsunami would probably result. Runup distances of 10 m over a 30-km-long stretch of the Santa Barbara coastline are predicted for a recurrence of the Goleta slide, and a runup of 3 m over a comparable stretch of the Los Angeles coastline is modeled for the Palos Verdes debris avalanche. © 2009 The Geological Society of America., Oceanography
Summary of the Meetings
Summary of the Meetings
THE 95th annual meeting of the American Society of Ichthyologists and Herpetologists (ASIH) was held at the Grand Sierra Resort, Reno, Nevada from 15−19 July 2015 in conjunction with the 31st annual meeting of the American Elasmobranch Society (AES), the 73rd annual meeting of the Herpetologists’ League (HL), and the annual meeting of the Neotropical Ichthyological Association. A total of 737 attendees were in Reno (360 Professionals, 337 Students, 17 Volunteers, 7 High School Students, 3 PARC Workshop Attendees, 15 Accompanying Persons, and 22 representatives for Exhibitors). Twenty-two nations were listed for our attendees (Australia, Brazil, Canada, China, France, Germany, India, Ireland, Japan, Korea, Laos, Mexico, Panama, Saudi Arabia, Spain, Switzerland, Taiwan, Thailand, United Kingdom, United States, and Uruguay). The students accounted for nearly half of the attendees, and the international flavor of our meetings is a highlight of the JMIH meeting.
Summer-time use of west coast US National Marine Sanctuaries by migrating sooty shearwaters (Puffinus griseus)
Summer-time use of west coast US National Marine Sanctuaries by migrating sooty shearwaters (Puffinus griseus)
Non-breeding sooty shearwaters are the most abundant seabird in the California Current Large Marine Ecosystem (CCLME) during boreal spring and summer months. This, combined with relatively great energy demands, reliance on patchy, shoaling prey (krill, squid, and forage fishes), and unconstrained mobility free from central-place-foraging demands-make shearwaters useful indicators of ecosystem variability. During 2008 and 2009, we used satellite telemetry to evaluate shearwater ranging patterns throughout the CCLME and specifically within the US Exclusive Economic Zone (EEZ) among birds captured at three locations: Columbia River Plume, WA; Monterey Bay, CA; and Santa Barbara Channel, CA. Shearwaters ranged throughout the entire CCLME from southeast Alaska to southern Baja California, Mexico. Within the EEZ during 2008 and 2009, shearwaters spent 68% and 46% of time over the shelf (<200. m), 27% and 43% of time over the slope (200-1000. m), and 5% and 11% of time over the continental rise and abyssal regions (>1000. m), respectively. In 2008 and 2009, shearwaters spent 22% and 25% of their time in the EEZ within the five west coast National Marine Sanctuaries, respectively; high utilization occurred in non-sanctuary waters of the EEZ. Shearwater utilization distribution (based on the Brownian-bridge movement model) among sanctuaries was disproportionate according to sanctuary availability (based on area) within the EEZ. Shearwaters utilized the Monterey Bay sanctuary (2008, 2009) and the Channel Islands sanctuary (2009) disproportionately more than other sanctuaries. Although all five sanctuaries were used by shearwaters, waters outside sanctuary zones appeared significantly more important and likely supported large aggregations of shearwaters. Utilization distributions among individual birds from three discrete capture locations were variable and revealed greater similarity in space-use sharing within capture-location groupings and during 2008 when shearwaters were more aggregated than in 2009. We identified several regional " habitat hotspot" areas, including the Columbia River Plume, Cape Blanco, Monterey Bay, Estero/San Luis Obispo Bays, and the eastern Santa Barbara Channel through the inner Southern California Bight. © 2012., Cited By (since 1996):1, Marine Mammals, Birds & Turtles, CODEN: BICOB
Surface ocean-lower atmosphere interactions in the Northeast Pacific Ocean Gyre: Aerosols, iron, and the ecosystem response
Surface ocean-lower atmosphere interactions in the Northeast Pacific Ocean Gyre: Aerosols, iron, and the ecosystem response
Here we report measurements of iron and aluminum in surface and subsurface waters during late March and late May of 2001 on transects between central California and Hawaii. A large cloud of Asian dust was detected during April 2001, and there was a clear signal in surface water iron due to aerosol deposition on the May transect. Iron and aluminum concentrations increased synchronously by 0.5 and 2 nM along the southern portion of the transect, which includes the Hawaii Ocean Time series (HOT) station, from background values in March (0.1 to 0.2 nM Fe). These changes occured in a ratio that is close to the crustal abundance ratio of the metals, which indicates a soil aerosol source. A vertical profile of dissolved iron was also measured at the HOT station in late April and this profile also shows a large increase near the surface. Direct observations of aerosol iron concentration at Mauna Loa Observatory on Hawaii indicate that aerosol concentrations were significantly lower than climatological values during this period. Soil aerosol concentrations along the transect were estimated using the real-time Navy Aerosol Analysis and Prediction System (NAAPS). The NAAPS results show a large meridional gradient with maximum concentrations in the boundary layer north of 30°N. However, the deposition of iron and aluminum to surface waters was highest south of 25°N, near Hawaii. There were only weak signals in the ecosystem response to the aerosol deposition., Cited By (since 1996):64, Oceanography, Downloaded from: http://onlinelibrary.wiley.com/doi/10.1029/2002GB002004/pdf (16 June 2014).
Surprising episodic recruitment and growth of Antarctic sponges
Surprising episodic recruitment and growth of Antarctic sponges
Sponges are the most conspicuous component of the Antarctic benthic ecosystem, a system under stress both from climate change and fishing activities. Observations over four decades are compiled and reveal extremely episodic sponge recruitment and growth. Recruitment occurred under different oceanographic conditions on both sides of McMurdo Sound. Most of the sponges appear to have recruited in the late 1990s–2000. Observations from 2000 to 2010 follow thirty years of relative stasis with very little sponge recruitment or growth followed by a general pattern of recruitment by some forty species of sponges. That there was almost no recruitment observed on natural substrata emphasizes the contrast between potential and realized recruitment. This unique data set was derived from a region noted for physical stasis, but the episodic ecological phenomena highlight the importance of rare events. Against a background of intermittent food resources and the low metabolic costs of stasis, understanding the causes of irregular larval supply, dispersal processes, recruitment success and survivorship becomes critical to predicting ecosystem dynamics and resilience in response to increasing environmental change. Our time-series emphasizes that long-term data collection is essential for meaningful forecasts about environmental change in the unique benthic ecosystems of the Antarctic shelf.
Surveillance for zoonotic and selected pathogens in harbor seals phoca vitulina from central California
Surveillance for zoonotic and selected pathogens in harbor seals phoca vitulina from central California
The infection status of harbor seals Phoca vitulina in central California, USA, was evaluated through broad surveillance for pathogens in stranded and wild-caught animals from 2001 to 2008, with most samples collected in 2007 and 2008. Stranded animals from Mendocino County to San Luis Obispo County were sampled at a rehabilitation facility: The Marine Mammal Center (TMMC, n = 175); wild-caught animals were sampled at 2 locations: San Francisco Bay (SF, n = 78) and Tomales Bay (TB, n = 97), that differed in degree of urbanization. Low prevalences of Salmonella, Campylobacter, Giardia, and Cryptosporidium were detected, in the feces of stranded and wild-caught seals. Clostridium perfringens and Escherichia coli were more prevalent in the feces of stranded (58% [78 out of 135] and 76% [102 out of 135]) than wild-caught (42% [45 out of 106] and 66% [68 out of 106]) seals, whereas Vibrio spp. were 16 times more likely to be cultured from the feces of seals from SF than TB or TMMC (p < 0.005). Brucella DNA was detected in 3.4% of dead stranded harbor seeds (2 out of 58). Type A influenza was isolated from feces of 1 out of 96 wild-caught seals. Exposure to Toxoplasma gondii, Sarcocystis neurona, and type A influenza was only detected in the wild-caught harbor seals (post-weaning age classes), whereas antibody titers to Leptospira spp. were detected in stranded and wild-caught seals. No stranded (n = 109) or wild-caught (n = 217) harbor seals had antibodies to phocine distemper virus, although a single low titer to canine distemper virus was detected. These results highlight the role of harbor seals as sentinel species for zoonotic and terrestrial pathogens in the marine environment., Harbor Seals
Survival and behavior of previously captive harbor seals after release into the wild
Survival and behavior of previously captive harbor seals after release into the wild
Downloaded from: www.nmfs.noaa.gov (4 August 2014). Harbor Seals
Survival probabilities and movements of harbor seals in central California
Survival probabilities and movements of harbor seals in central California
Article in Press, Harbor seal numbers and population trajectories differ by location in central California. Within San Francisco Bay (SFB) counts have been relatively stable since the 1972 Marine Mammal Protection Act, but in coastal areas like Tomales Bay (TB), counts increased before stabilizing in the 1990s. Emigration, poor survival, and environmental effects have been hypothesized as contributors to differences between trajectories; however, basic demographic data were not available to evaluate these hypotheses. We monitored 32 radio-tagged adult females (SFB n = 17, TB n = 15) for 20 mo (2011-2013), and estimated survival, resight, and movement probabilities using mark-resight analyses and multistate mark-resight models. Annual survival probability for both sites was 0.90 (95% CI = 0.18-0.99). Six seals were observed moving between locations resulting in an estimated probability of 0.042 (95% CI = 0.023-0.076) per month equal movement between sites. Resight probability was less in SFB relative to TB, likely due to differential haul-out access, area surveyed, visibility, and resight effort. Because of wide confidence intervals and low precision of these first estimates of adult female harbor seal survival in California, this demographic must be further examined to dismiss its contribution to differing population trajectories. Using aerial survey data, we estimated 950 harbor seals in SFB (95% CI = 715-1,184) confirming numbers are still stable.
Suspended particulate layers and internal waves over the southern Monterey Bay continental shelf: An important control on shelf mud belts?
Suspended particulate layers and internal waves over the southern Monterey Bay continental shelf: An important control on shelf mud belts?
Physical and optical measurements taken over the mud belt on the southern continental shelf of Monterey Bay, California documented the frequent occurrence of suspended particulate matter features, the majority of which were detached from the seafloor, centered 9–33 m above the bed. In fall 2011, an automated profiling mooring and fixed instrumentation, including a thermistor chain and upward-looking acoustic Doppler current profiler, were deployed at 70 m depth for 5 weeks, and from 12 to 16 October a long-range autonomous underwater vehicle performed across-shelf transects. Individual SPM events were uncorrelated with local bed shear stress caused by surface waves and bottom currents. Nearly half of all observed SPM layers occurred during 1 week of the study, 9–16 October 2011, and were advected past the fixed profiling mooring by the onshore phase of semidiurnal internal tide bottom currents. At the start of the 9–16 October period, we observed intense near-bed vertical velocities capable of lifting particulates into the middle of the water column. This “updraft” event appears to have been associated with nonlinear adjustment of high-amplitude internal tides over the mid and outer shelf. These findings suggest that nonlinear internal tidal motions can erode material over the outer shelf and that, once suspended, this SPM can then be transported shoreward to the middle and shallow sections of the mud belt. This represents a fundamental broadening of our understanding of how shelf mud belts may be built up and sustained.
Swarming benthic crustaceans in the Bering and Chukchi seas and their relation to geographic patterns in gray whale feeding
Swarming benthic crustaceans in the Bering and Chukchi seas and their relation to geographic patterns in gray whale feeding
Swarms differed in their geographic extent, local biomass, and life stages of swarming individuals and thus in their availability to feeding Eschrichtius robustus. Immature amphipods apparently swarmed for dispersal, whereas cumaceans probably swarmed for mating. All life stages of the hyperbenthic mysids occurred above the sea floor. Although the geographic spread of mysid swarms and shrimp communities was much greater than for the amphipod and cumacean swarms, the latter swarmed in denser patches to produce higher local biomass. Crustacean swarms are important in describing the geographic patterns of gray whale feeding from the Chukchi Sea to Baja California. The primary feeding ground is in the S Chukchi Sea and especially the N Bering Sea, where gray whales suck infaunal amphipods from fine sand. The primary feeding ground is divided into a relatively deep zone (>20 m), where tube-dwelling ampeliscid amphipods are the major prey, and a shallow zone (<20 m), where burrowing pontoporeid amphipods dominate. The secondary feeding ground is in the S Bering Sea along the E Alaska Peninsula and adjacent Alaskan mainland where shrimp and mysids are the major prey. -from Authors, Cited By (since 1996):16, Invertebrates, Marine Mammals, Birds & Turtles

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