Articles

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


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A switch from Si(OH)4 to NO- 3 depletion in the glacial Southern Ocean
A switch from Si(OH)4 to NO- 3 depletion in the glacial Southern Ocean
Phytoplankton in the Antarctic deplete silicic acid (Si(OH)4) to a far greater extent than they do nitrate (NO3 -). This pattern can be reversed by the addition of iron which dramatically lowers diatom Si(OH)4:NO3 - uptake ratios. Higher iron supply during glacial times would thus drive the Antarctic towards NO3 - depletion with excess Si(OH)4 remaining in surface waters. New δ30Si and δ15N records from Antarctic sediments confirm diminished Si(OH)4 use and enhanced NO3 - depletion during the last three glaciations. The present low-Si(OH)4 water is transported northward to at least the subtropics. We postulate that the glacial high-Si(OH)4 water similarly may have been transported to the subtropics and beyond. This input of Si(OH)4 may have caused diatoms to displace coccolithophores at low latitudes, weakening the carbonate pump and increasing the depth of organic matter remineralization. These effects may have lowered glacial atmospheric pCO2 by as much as 60 ppm., Cited By (since 1996):108, CODEN: GPRLA, Oceanography, Antarctica
A time series of benthic flux measurements from Monterey Bay, CA
A time series of benthic flux measurements from Monterey Bay, CA
In situ incubation chamber measurements of benthic nutrient recycling rates were made on the Monterey Bay shelf at 100 m during various years and seasons. Variability in nutrient (Si, PO42+, NH3, NO3−) and trace metal (Mn, Fe (II), Cu) fluxes correlate with variability in the amount of organic carbon oxidized on the sea floor. Patterns of primary productivity show a mid-year maxima, consistent with the timing of increased rates of benthic Corg and opal recycling. High rates of Corg rain to the shelf promote nitrate consumption at a rate that equals or exceeds ammonia efflux. Low rates of Corg rain promote greater efflux of DIN; thus these margin sediments provide a negative feedback to local productivity cycles. The efflux of iron (II) from shelf sediments is sufficient to support >100% of new production, yet Fe flux is positively correlated with Corg recycling which lags the maximum in new production. On account of this time lag, diagenetically recycled Fe is not likely a micro-nutrient trigger of new production, but could serve as a positive feedback. Bio-irrigation rates are seasonally variable by 30% but maximal during the maximum productivity months.
A time series of benthic flux measurements from Monterey Bay, CA
A time series of benthic flux measurements from Monterey Bay, CA
In situ incubation chamber measurements of benthic nutrient recycling rates were made on the Monterey Bay shelf at 100m during various years and seasons. Variability in nutrient (Si, PO 4 2+, NH 3, NO 3 -) and trace metal (Mn, Fe (II), Cu) fluxes correlate with variability in the amount of organic carbon oxidized on the sea floor. Patterns of primary productivity show a mid-year maxima, consistent with the timing of increased rates of benthic C org and opal recycling. High rates of C org rain to the shelf promote nitrate consumption at a rate that equals or exceeds ammonia efflux. Low rates of C org rain promote greater efflux of DIN; thus these margin sediments provide a negative feedback to local productivity cycles. The efflux of iron (II) from shelf sediments is sufficient to support > 100% of new production, yet Fe flux is positively correlated with C org recycling which lags the maximum in new production. On account of this time lag, diagenetically recycled Fe is not likely a micro-nutrient trigger of new production, but could serve as a positive feedback. Bio-irrigation rates are seasonally variable by 30% but maximal during the maximum productivity months. © 2003 Elsevier Science Ltd. All rights reserved., Cited By (since 1996):65, CODEN: CSHRD, Oceanography
A worldwide review of the food of nudibranch mollusks. Part II. The suborder dendronotacea
A worldwide review of the food of nudibranch mollusks. Part II. The suborder dendronotacea
The prey items of 108 species representing all 10 families of the suborder Dendronotacea are presented in shortened form from the much larger electronic database accessible on the Web., Cited By (since 1996):9, Invertebrates
AUV-derived geographical photomosaics - using multibeam bathymetry to correct image placement
AUV-derived geographical photomosaics - using multibeam bathymetry to correct image placement
A photomosaicking technique was improved by incorporating data from multibeam bathymetry acquired simultaneously with the seafloor images. AUV navigation logs are used to geographically place the images, as has been previously documented. This revision accounts for navigation offset and drift by using multibeam processing tools to refine image placement. The processed bathymetric grid combined with vehicle logs allow for the scaling of image size and illumination to produce more accurate photomosaics. © 2015 MTS., Export Date: 6 May 2016, Conference Paper, Article Number: 7404440
Abiotic regulation of investment in sexual versus vegetative reproduction in the clonal kelp Laminaria sinclairii (Laminariales, Phaeophyceae)
Abiotic regulation of investment in sexual versus vegetative reproduction in the clonal kelp Laminaria sinclairii (Laminariales, Phaeophyceae)
Clonal kelp taxa may reproduce both sexually and vegetatively resulting in a potential trade-off in the allocation of acquired carbon and nitrogen resources. Such trade-offs may dictate a different response of clonal kelps to varying environmental conditions relative to aclonal kelp taxa. Laboratory temperature and nutrient manipulation experiments demonstrated that investment in sexual and vegetative reproduction in Laminaria sinclairii (Harv. ex Hook. f. et Harv.) Farl., C. L. Anderson et D. C. Eaton was regulated by different abiotic factors. Sorus production (investment in sexual reproduction) and blade growth were significantly higher at 12°C compared to 17°C, regardless of nutrient concentration. Net carbon storage and depletion in rhizomes were observed in the low- and high-temperature treatments, respectively, suggesting that carbon stores were not responsible for increased growth. Rhizome elongation (investment in vegetative reproduction), on the other hand, was significantly higher in 12μM NO3- than in 2μM NO3-, irrespective of temperature. This increase in rhizome growth was concurrent with elevated rhizome percent tissue nitrogen levels also observed in treatments with higher nutrients, again indicating a growth response to treatment independent of previous nutrient stores. These results suggest that regulation of growth and investment in sexual reproduction in L. sinclairii is similar to that in aclonal kelps (i.e., warmer temperatures result in decreased reproductive output). Additionally, depletion of carbon and nitrogen from rhizomes in suboptimal conditions confirms the role of clonal kelp rhizomes in carbon and nutrient storage. © 2011 Phycological Society of America., Seaweeds, CODEN: JPYLA
Abundance and distribution of marine mammals in nearshore waters of Monterey Bay, California
Abundance and distribution of marine mammals in nearshore waters of Monterey Bay, California
We studied the seasonal abundance and spatial distribution of marine mammals in nearshore waters (<1 km from shore) of Monterey Bay, California, during 1999 and 2000. The most abundant mammal was California sea lion, Zalophus californianus, followed by harbor porpoise, Phocoena phocoena, sea otter, Enhydra lutris, and harbor seal, Phoca vitulina. Seasonal abundance of harbor porpoise in the survey area was greatest during winter, pinnipeds were most abundant during autumn, and sea otters were most abundant during spring and autumn. California sea lions were more abundant in 2000 than in 1999. Harbor porpoise were found in water of lesser clarity than expected by chance, and sea lions were found more often in water of intermediate clarity. Distribution of sea otters and harbor seals were not affected by water clarity., Cited By (since 1996):2, Marine Mammals, Birds & Turtles
Abundance, distribution, and habitat of Leatherback turtles (Dermochelys coriacea) off California, 1990-2003
Abundance, distribution, and habitat of Leatherback turtles (Dermochelys coriacea) off California, 1990-2003
Leatherback turtles (Dermochelys coriacea) are regularly seen off the U.S. West Coast, where they forage on jellyfish (Scyphomedusae) during summer and fall. Aerial line transect surveys were conducted in neritic waters (<92 m depth) off central and northern California during 1990-2003, providing the first foraging population estimates for Pacific leatherback turtles. Males and females of about 1.1 to 2.1 m length were observed. Estimated abundance was linked to the Northern Oscillation Index and ranged from 12 (coefficient of variation [CV]=0.75) in 1995 to 379 (CV=0.23) in 1990, averaging 178 (CV=0.15). Greatest densities were found off central California, where oceanographic retention areas or upwelling shadows created favorable habitat for leatherback turtle prey. Results from independent telemetry studies have linked leatherback turtles off the U.S. West Coast to one of the two largest remaining Pacific breeding populations, at Jamursba Medi, Indonesia. Nearshore waters off California thus represent an important foraging region for the critically endangered Pacific leatherback turtle.
Abundance, distribution, and habitat of leatherback turtles (Dermochelys coriacea) off California, 1990-2003
Abundance, distribution, and habitat of leatherback turtles (Dermochelys coriacea) off California, 1990-2003
Leatherback turtles (Dermochelys coriacea) are regularly seen off the U.S. West Coast, where they forage on jellyfish (Scyphomedusae) during summer and fall. Aerial line-transect surveys were conducted in neritic waters (<92 m depth) off central and northern California during 1990-2003, providing the first foraging population estimates for Pacific leatherback turtles. Males and females of about 1.1 to 2.1 m length were observed. Estimated abundance was linked to the Northern Oscillation Index and ranged from 12 (coefficient of variation [CV] = 0.75) in 1995 to 379 (CV = 0.23) in 1990, averaging 178 (CV = 0.15). Greatest densities were found off central California, where oceanographic retention areas or upwelling shadows created favorable habitat for leatherback turtle prey. Results from independent telemetry studies have linked leatherback turtles off the U.S. West Coast to one of the two largest remaining Pacific breeding populations, at Jamursba Medi, Indonesia. Nearshore waters off California thus represent an important foraging region for the critically endangered Pacific leatherback turtle., Cited By (since 1996):16, CODEN: FSYBA, Marine Mammals, Birds & Turtles
Abundance, diversity and temporal variability in a California intertidal nudibranch assemblage
Abundance, diversity and temporal variability in a California intertidal nudibranch assemblage
A 40-month study of a nudibranch assemblage within a 250 m2 intertidal area at Asilomar State Beach, California, USA, indicated that dominance was shared among 9 species which comprised 87% of the total number of individuals enumerated. These 9 species also showed high frequency of occurrence in the area. The number of nudibranch species counted per month was shown to be independent of weather and tide conditions, but the numbers of individuals and diversity values were correlated with wave action, lower values and numbers being tabulated during times of storms. Cumulative plots of diversity and species number based upon 15 min enumeration times indicated adequate assessment of diversity and species number after 60 min of sampling. The number of species and individuals and the diversity varied from month to month over the 40 months, but these variations were shown to be statistically insignificant or to be correlated with weather. Hence, it was concluded that the assemblage was a stable one, structured primarily by the 9 dominant species. No statistically significant seasonal or annual changes were observed in the assemblage. Diversity was found to correlate most highly with species number and less with number of individuals. The average number of species found per month was 13, the average number of individuals 104, and the average monthly diversity (HH}) was 1.82. Significant positive and negative correlations between abundances of certain species were found. These were attributed to occurrence of prey items or to synchrony of reproduction. There was no evidence of migration, and resident status for one dominant species was established. Comparison of the present study with earlier work suggested that a stable nudibranch assemblage was not merely a local phenomenon. © 1978 Springer-Verlag., Cited By (since 1996):15, CODEN: MBIOA, Invertebrates
Abundance, seasonal distribution and population composition of balaenopterid whales in the Canal de Ballenas, Gulf of California, Mexico
Abundance, seasonal distribution and population composition of balaenopterid whales in the Canal de Ballenas, Gulf of California, Mexico
Blue whales Balaenoptera musculus were most abundant in April and May while minke B. acutorostrata whales were equally abundant throughout the year. Fin B. physalus and Bryde's whales B. edeni were found but fin whales were more abundant in winter and spring; numbers were negatively correlated with water temperature. Bryde's whales were more abundant in summer and fall; numbers were positively correlated with water temperature. The percentage of identified individual adults that were females with calves was 10.6 for Bryde's and 2.7 for fin whales., Cited By (since 1996):13, Marine Mammals, Birds & Turtles
Access to Online Historical Aerial Photography Collections
Access to Online Historical Aerial Photography Collections
The authors review how access to historical aerial photograph collections has evolved in response to technological developments and addresses areas for further advancement, with a particular emphasis on developing, preserving, and sustaining online collections. The authors focus specifically on the areas of metadata, the Semantic Web and linked data, and sustainability through collaboration. The article includes brief case studies, highlighting various projects involving the aerial photography collections at the University of Minnesota. The conclusion asserts the critical role played by geographic information librarians in effectively carrying out the strategies described in the article as they relate to the long-term sustainability of digital geospatial collections.
Accumulation rate and mixing of shelf sediments in the Monterey Bay National Marine Sanctuary
Accumulation rate and mixing of shelf sediments in the Monterey Bay National Marine Sanctuary
The distribution of excess 210Pb in 31 sediment cores was used to determine modern (last 100 yr) mass accumulation rates and the depth of sediment mixing on the continental shelf between Pacifica and Monterey, California, USA. Apparent mass accumulation rates average 0.27 g cm-2 yr-1 and range from 0.42 g cm-2 yr-1 to 0.12 g cm-2 yr-1. Accumulation rates were highest at mid-shelf water depths (60-100 m) adjacent to major rivers and near the head of the Ascension submarine canyon. Cores from water depths of less than 65 m had low, uniform 210Pb activity profiles and sandy textures. The uppermost 5-13 cm of 15 cores had uniform 210Pb activity profiles above a region of steadily decreasing 210Pb activity. This phenomenon was attributed to sediment mixing. The thickness of this upper layer of uniform 210Pb activity decreased southward from 13 cm, west of Pacifica, to less than 5 cm, near Monterey Canyon. This southward decrease may be attributed to shallower bioturbation in the southern study area. Integrated excess 210Pb activities were generally higher where sedimentation rates were high. They were also higher with increasing distance from major rivers. Thus, sedimentation rate alone does not explain the distribution of integrated excess 210Pb in this study area. Excess 210Pb in the seafloor is controlled by other factors such as sediment texture, the atmospheric deposition rate of 210Pb, and the residence time of sediment particles in the water column. © 2002 Elsevier Science B.V. All rights reserved., Cited By (since 1996):28, CODEN: MAGEA, Oceanography
Acoustic monitoring of Atlantic cod (Gadus morhua) in Massachusetts Bay
Acoustic monitoring of Atlantic cod (Gadus morhua) in Massachusetts Bay
Atlantic cod (Gadus morhua) stocks in northeastern US waters are depleted and stock recovery has been slow; research into the spawning behaviour of this species can help inform conservation and management measures. Male cod produce low-frequency grunts during courtship and spawning. Passive acoustic monitoring (PAM) offers a different perspective from which to investigate the occurrence, spatial extent and duration of spawning cod aggregations. A marine autonomous recording unit was deployed in the "Spring Cod Conservation Zone" (SCCZ) located in Massachusetts Bay, western Atlantic, to record cod grunts from April-June 2011. Cod grunts were present on 98.67% of the recording days (n = 75 days). They occurred across all 24 h, although significantly more grunts were found during the day than night-time (p = 0.0065). Grunt durations ranged from 57-360 ms, and the fundamental frequency and second harmonic had mean peak frequencies of 49.7 ± 5.6 and 102.9 Hz ± 10.9 sd, respectively. Cod grunt rates were low compared with those reported for other spawning fish, and may be indicative of diel movement patterns. Next steps will focus on expanding PAM coverage within the SCCZ, alongside prospecting for unknown spawning grounds within existing archival data. © 2013 © United States Government [NOAA] 2013. Published by Oxford University Press., Fish and Fisheries, CODEN: ICESE
Acoustical deterrents in marine mammal conflicts with fisheries
Acoustical deterrents in marine mammal conflicts with fisheries
Acoustical deterrents in marine mammal conflicts with fisheries. A workshop held February 17-18, 1986 at Newport, Oregon. Oregon State University, Publ. No. ORESU-W-86-001. 116 pp.
Acoustical deterrents in marine mammal conflicts with fisheries
Acoustical deterrents in marine mammal conflicts with fisheries
Oregon State University, Publ. No. ORESU-W-86-001. 116 pp.
Active acoustic examination of the diving behavior of murres foraging on patchy prey
Active acoustic examination of the diving behavior of murres foraging on patchy prey
During the 2008 and 2009 breeding seasons of murres Uria spp., we combined visual observations of these predators with active acoustics (sonar), fish trawls, zooplankton net tows, and hydrographic measurements in the area surrounding breeding colonies in the southeastern Bering Sea. We acoustically detected thousands of bubble trails that were strongly correlated with the number of visually detected murres, providing a new tool for quantitatively studying the foraging ecology of diving birds. At the regional scale, the number of acoustically detected bubble trails, which served as a proxy for diving murre abundance, was related to the combined availability and vertical accessibility of squid, krill, and pollock. There were, however, no clear relationships at this scale between diving murres and any individual prey taxon, highlighting the importance of prey diversity to these animals. Individual krill patches targeted by murres had higher krill density and were located shallower than the mean depth of krill patches, but were similar in total krill abundance and overall size. The diving depth of murres within krill patches was highly correlated to the depth of the upper edge of these patches, whereas murres found outside of krill patches showed a depth distribution similar to that of juvenile pollock. Throughout the study area, murres showed strong diel patterns in their diving behavior in response to the diel migrations of their prey. These results suggest that murres select prey with specific patch characteristics implying effective information gathering about prey by murres. The high proportion of diving murres in aggregations and their consistent inter-individual spacing support the hypothesis that intraspecific local enhancement may facilitate foraging in these predators. © 2011 Inter-Research., Cited By (since 1996):15, CODEN: MESED, Marine Mammals, Birds & Turtles
Acute toxicity of mercury and selenium to Crassostrea gigas embryos and Cancer magister larvae
Acute toxicity of mercury and selenium to Crassostrea gigas embryos and Cancer magister larvae
The possible modification of mercury toxicity by selenium in embryos of the Pacific oyster Crassostrea gigas and the larvae of the crab Cancer magister was investigated. Mercury concentration eliciting abnormal development in 50% of the oyster embryos (EC50) was 5.7 μg l-1 (48 h) and mortality in 50% of the crab larvae (LC50) occurred with 6.6 μg l-1 (96 h). The 48 h EC50 for selenium was greater than 10,000 μg l-1 for oyster embryos and the 96 h LC50 for crab zoeae was 1040 μg l-1. The response from each species, when exposed to both toxicants, revealed that a high level of selenium (≥5,000 μg l-1) increased mercury toxicity. Moderate selenium concentrations (10 to 1,000 μg l-1) tended to decrease mercury toxicity, although no statistical verification could be made. The order of administration of toxicants had no effect on the response of Crassostrea gigas embryos. Early developmental stages (≤8 h) of C. gigas embryos were most sensitive to dissolved Hg; toxicant administration 24 h after fertilization resulted in no apparent abnormalities in development., Cited By (since 1996):7, CODEN: MBIOA, Invertebrates
Adapted to change
Adapted to change
The rate of energy expenditure and acquisition are fundamental components of an animals' life history. Within mammals the otariids (sea lions and fur seals) exhibits energetically expensive life styles, which can be challenging in equatorial regions where resources are particularly limited and unpredictable. To better understand how this energetically expensive life history pattern functions in an energetically challenging equatorial system, we concurrently measured the field metabolic rate (FMR) and foraging behavior of lactating Galapagos sea lions (GSL) rearing pups and yearlings. Females with pups tended to forage to the north, diving deeper, epi and mesopelagically compared to females with yearlings, which foraged to the west and performed dives to the sea bed that were shallower. FMR did not differ between females with pups or yearlings but, increased significantly with % time spent at-sea. Females with yearlings had higher water influx, suggesting greater food intake, but had lower body condition. The FMR (4.08 +/- 0.6 W/kg) of GSL is the lowest measured for any otariid, but is consistent with Galapagos fur seals which also exhibit low FMR. The observation that these two otariids have reduced energy requirements is consistent with an adaptation to the reduced prey availability of the Galapagos marine environment compared to other more productive marine systems., In Press

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