Search results | Digital Commons of Moss Landing Marine Laboratories

Title: Growth rate and age determination of bamboo corals from the northeastern Pacific Ocean using refined 210Pb dating,
Description: Bamboo corals from Davidson Seamount and from the Gulf of Alaska were aged using a refined 210Pb dating technique. The goal was to determine growth rates and age for several bamboo corals with higher precision. Radiometric results for 2 Davidson Seamount corals (Keratoisis sp.) converged on a radial growth rate of ∼0.055 mm yr-1. One colony was aged at 98 ± 9 yr, with an average axial growth rate of ∼0.7 cm yr -1. The age of a large colony was >145 yr with an estimated axial growth rate of 0.14 to 0.28 cm yr-1. Inconsistent rates may indicate nonlinear axial growth. A Keratoisis sp. specimen from the Gulf of Alaska was aged at 116 ± 29 yr from a radial growth rate of ∼0.056 mm yr -1, which led to an average axial growth rate of ∼1.0 cm yr -1. An Isidella tentaculum colony was aged at 53 ± 10 yr and grew most rapidly with a radial growth rate of ∼0.10 mm yr-1 and an average axial growth rate of ∼1.4 cm yr-1; however, the 210Pb decay pattern may have provided evidence for either a hiatus in radial growth or environmental changes in 210Pb. Our findings of slow growth and long life compared favorably with other bamboo coral studies and provided age estimates with greater precision. The high longevity of bamboo coral is an indication that recovery from disturbance or removal may take decades to a century. These age data provide a basis for a defensible position on the protection of bamboo coral and essential information for describing other life history characteristics., Cited By (since 1996):12, CODEN: MESED, ,
Author: Andrews, Stone, Lundstrom, Devogelaere
Date: 2009-01-01T00:00:00Z

Title: Using x-ray microscopy and Hg L3 XANES to study Hg binding in the rhizosphere of spartina cordgrass,
Description: San Francisco Bay has been contaminated historically by mercury from mine tailings as well as contemporary industrial sources. Native Spartina foliosa and non-native S. alterniflora-hybrid cordgrasses are dominant florae within the SF Bay estuary environment. Understanding mercury uptake and transformations in these plants will help to characterize the significance of their roles in mercury biogeochemical cycling in the estuarine environment. Methylated mercury can be biomagnified up the food web, resulting in levels in sport fish up to 1 million times greater than in surrounding waters and resulting in advisories to limit fish intake. Understanding the uptake and methylation of mercury in the plant rhizosphere can yield insight into ways to manage mercury contamination. The transmission X-ray microscope on beamline 6-2 at the Stanford Synchrotron Radiation Lightsource (SSRL) was used to obtain absorption contrast images and 3D tomography of Spartina foliosa roots that were exposed to 1 ppm Hg (as HgCl2) hydroponically for 1 week. Absorption contrast images of micrometer-sized roots from S. foliosa revealed dark particles, and dark channels within the root, due to Hg absorption. 3D tomography showed that the particles are on the root surface, and slices from the tomographic reconstruction revealed that the particles are hollow, consistent with microorganisms with a thin layer of Hg on the surface. Hg L3 XANES of ground-up plant roots and Hg L3 micro-XANES from microprobe analysis of micrometer-sized roots (60-120 μm in size) revealed three main types of speciation in both Spartina species: Hg-S ligation in a form similar to Hg(II) cysteine, Hg-S bonding as in cinnabar and metacinnabar, and methylmercury- carboxyl bonding in a form similar to methylmercury acetate. These results are interpreted within the context of obtaining a "snapshot" of mercury methylation in progress. © 2009 American Chemical Society., Cited By (since 1996):27, CODEN: ESTHA, ,
Author: Patty, Barnett, Mooney, Kahn, Levy, Liu, Pianetta, Andrews
Date: 2009-01-01T00:00:00Z

Title: Recent increase in atmospheric deposition of mercury to California aquatic systems inferred from a 300-year geochronological assessment of lake sediments,
Description: Age-dated sediment cores from 4 remote lakes across California were analyzed for total Hg (Hg T) concentration as a function of pre- and post-industrialization. Particle size, magnetic susceptibility and organic C and N, were measured to determine if the Hg concentration in sediment cores could be related to atmospheric deposition and/or watershed processes. Results indicate that (a) for each lake modern (1970-2004) Hg T lake sediment concentrations have increased by an average factor of 5 times more than historic (pre-1850) Hg T concentrations; (b) the ratio of modern to pre-industrial lake sediment Hg T for these lakes are higher than estimated for other locations where atmospheric deposition is presumed to be the main source of Hg; (c) 2 of the 4 studied lakes demonstrated significant relationships between Hg T concentrations and percentage organic material (r 2 = 0.68 and p < 0.01; r 2 = 0.67 and p < 0.01) whereas the other two indicated no significant relationship (r 2 = 0.05 and p = 0.51; r 2 = 0.12 and p = 0.36). © 2007 Elsevier Ltd. All rights reserved., Cited By (since 1996):13, CODEN: APPGE, ,
Author: Sanders, Coale, Gill, Andrews, Stephenson
Date: 2008-01-01T00:00:00Z

Title: Age of black coral (Antipathes dendrochristos) colonies, with notes on associated invertebrate species,
Description: In 2005, a dead 2.1-m high colony of the Christmas tree black coral, Antipathes dendrochristos Opresko, 2005, was collected from 106 m of water off southern California. Based on growth increment counts, a radiocarbon ( 14C) analysis, and an indirect corroboration by lead-210 dating from a second, live colony, the colony was about 140 yrs old when it died. The dead skeleton was heavily colonized by invertebrates with 2554 individuals living on the colony. Corophioid amphipods, sea anemones, brittle stars, and crinoids dominated this assemblage. Thus, along with living colonies, it is arguable that the destruction of dead antipatharian colonies may have as yet unknown effects on a range of deep-water organisms. © 2007 Rosenstiel School of Marine and Atmospheric Science of the University of Miami., Cited By (since 1996):13, Invertebrates, CODEN: BMRSA, ,
Author: Love, Yoklavich, Black, Andrews
Date: 2007-01-01T00:00:00Z

Title: Lead-radium dating of orange roughy (Hoplostethus atlanticus): Validation of a centenarian life span,
Description: Life-span estimates for orange roughy (Hoplostethus atlanticus) range from ∼20 years to well over 100 years. In this study, an improved lead-radium dating technique provided independent age estimates from sagittal otoliths. This technique used the known properties of radioactivity for lead-210 and radium-226 to determine the validity of fish age estimates. An improvement to lead-radium dating using mass spectrometry allowed the use of smaller samples than previously possible; therefore, an application was made to otolith cores, the first few years of otolith growth. This approach circumvented the use of whole otoliths and alleviated many of the assumptions that were necessary in previous lead-radium dating applications. Hence, it was possible to critically evaluate lead-radium dating as a tool in fish age validation. The measurement of lead-radium ratios for a series of age groups that consisted of otolith cores, grouped based on growth-zone counts from thin sections, showed a high degree of correlation to the expected lead-radium ingrowth curve. This finding provided support for age estimation procedures using thin otolith sectioning. As independent estimates of age, the results indicated that fish in the oldest age group were at least 93 years old, providing robust support for a centenarian life span., Cited By (since 1996):14, CODEN: CJFSD, ,
Author: Andrews, Tracey, Dunn
Date: 2009-01-01T00:00:00Z

Title: Using bomb radiocarbon analyses to validate age and growth estimates for the tiger shark, Galeocerdo cuvier, in the western North Atlantic,
Description: Refined and validated age and growth determinations are necessary for a proper understanding of tiger shark (Galeocerdo cuvier) life history characteristics in the western North Atlantic (WNA). Age and growth estimates were derived from band counts of 238-sectioned vertebral centra. Bomb radiocarbon analysis of ten band pairs extracted from four vertebral sections suggested that band pairs are deposited annually up to age 20. Males and females were aged to 20 and 22 years, respectively, although longevity estimates predict maximum ages of 27 and 29 years, respectively. Two- and three-parameter von Bertalanffy and Gompertz growth functions fit to length at age data demonstrated that growth rates were similar for males and females up to around 200 cm fork length (FL) after which male growth slowed. Both sexes appear to reach maturity at age 10. The two-parameter von Bertalanffy growth function provided the best biological fit to length at age data generating parameter estimates of: L ∞ = 330 cm FL, k = 0.131 for males and L ∞ = 347 cm FL, k = 0.124 for females, with L 0 set at 62 cm FL. This study provides a rigorous description of tiger shark age and growth in the WNA and further demonstrates the utility of bomb radiocarbon as an age validation tool for elasmobranch fish. © 2008 Springer-Verlag., Cited By (since 1996):6, Fish and Fisheries, CODEN: MBIOA, ,
Author: Kneebone, Natanson, Andrews, Howell
Date: 2008-01-01T00:00:00Z