scholarly journals Radiocarbon in otoliths of yelloweye rockfish (Sebastes ruberrimus): a reference time series for the coastal waters of southeast Alaska

2004 ◽  
Vol 61 (3) ◽  
pp. 443-451 ◽  
Author(s):  
Lisa A Kerr ◽  
Allen H Andrews ◽  
Brian R Frantz ◽  
Kenneth H Coale ◽  
Thomas A Brown ◽  
...  
Keyword(s):  
Time Series ◽  
Coastal Waters ◽  
Age Validation ◽  
Ambient Seawater ◽  
Southeast Alaska ◽  
Reference Time ◽  
Initial Rise ◽  
Time Specific ◽  
Fish Otoliths ◽  
Age Estimates

Atmospheric testing of thermonuclear devices during the 1950s and 1960s created a global radiocarbon (14C) signal that has provided a useful tracer and chronological marker in oceanic systems and organisms. The bomb-generated 14C signal retained in fish otoliths can be used as a time-specific recorder of the 14C present in ambient seawater, making it a useful tool in age validation of fishes. The goal of this study was to determine 14C in otoliths of the age-validated yelloweye rockfish (Sebastes ruberrimus) to establish a reference time series for the coastal waters of southeast Alaska. Radiocarbon values from the first year's growth of 43 yelloweye rockfish otoliths plotted against estimated birth year produced a 14C time series (1940–1990) for these waters. The initial rise of 14C occurred in 1958 and 14C levels rose to peak values (60–70‰) between 1966 and 1971, with a subsequent declining trend through the end of the record in 1990 (–3.2‰). In addition, the 14C data confirmed the longevity of the yelloweye rockfish to a minimum of 44 years and strongly support higher age estimates. This 14C time series will be useful for the interpretation of 14C accreted in biological samples from these waters.

Bomb radiocarbon and lead - radium disequilibria in otoliths of bocaccio rockfish (Sebastes paucispinis): a determination of age and longevity for a difficult-to-age fish

2005 ◽  
Vol 56 (5) ◽  
pp. 517 ◽  
Author(s):  
Allen H. Andrews ◽  
Erica J. Burton ◽  
Lisa A. Kerr ◽  
Gregor M. Cailliet ◽  
Kenneth H. Coale ◽  
...  
Keyword(s):  
Time Series ◽  
Growth Zone ◽  
Reference Time ◽  
Bomb Radiocarbon ◽  
Age Estimates

Longevity estimates for the bocaccio rockfish (Sebastes paucispinis) using traditional techniques range from less than 20 years to approximately 50 years. Otoliths of bocaccio are difficult to age, and previous attempts to validate ages have been unsuccessful. Because otolith age suggests the bocaccio are reasonably long-lived, lead–radium dating was used in an attempt to independently age bocaccio otoliths. The measured 210Pb and 226Ra activities were among the lowest reported and resulted in poor radiometric age resolution; however, the break-and-burn technique clearly underestimated age in some cases with the longevity of the bocaccio being at least 31 years. To provide better age resolution, the bomb radiocarbon approach was applied to individual otoliths. Based on measured radiocarbon levels relative to a reference time-series, several specimens were aged at approximately 30–40 years. To evaluate these determinations, the remaining otolith of the pair was sectioned and aged blind. The result was an excellent fit to the reference time-series and a validation of the age estimates. The maximum age from growth zone counts was 37 ± 2 years, which is consistent with a reported maximum age of approximately 50 years.

A Contextual Evaluation of Composite Forecasts of Annual Earnings

2016 ◽  
Vol 19 (03) ◽  
pp. 1650014 ◽  
Author(s):  
Pieter T. Elgers ◽  
May H. Lo ◽  
Wenjuan Xie ◽  
Le Emily Xu
Keyword(s):  
Time Series ◽  
Firm Size ◽  
Predictive Accuracy ◽  
Relative Accuracy ◽  
Regulation Fair Disclosure ◽  
Fair Disclosure ◽  
Time Periods ◽  
Time Specific ◽  
Annual Earnings ◽  
The Impact

This study addresses the impact of firm- and time-specific attributes on the accuracy of composite forecasts of annual earnings, constructed from time-series, price-based, and analysts' forecasts. The attributes examined include firm size, analysts' coverage, and time periods pre-dating and following the implementation of regulation fair disclosure. Our results indicate that the relative accuracy of the composite forecasts is time-specific. In the pre-regulation fair disclosure period, composite forecasts significantly outperform each of the three individual forecast sources. Moreover, the extent of improvement in accuracy of composite forecasts is significantly higher for the smaller and lightly-covered firms. Collectively, these results suggest that the predictive accuracy of composite forecasts is contextual.

scholarly journals Patterns and trends in nutrients and phytoplankton in Dutch coastal waters: comparison of time-series analysis, ecological model simulation, and mesocosm experiments

1998 ◽  
Vol 55 (4) ◽  
pp. 620-634 ◽  
Author(s):  
I DEVRIES ◽  
R DUIN ◽  
J PEETERS ◽  
F LOS ◽  
M BOKHORST ◽  
...  
Keyword(s):  
Time Series ◽  
Time Series Analysis ◽  
Coastal Waters ◽  
Ecological Model ◽  
Model Simulation ◽  
Series Analysis ◽  
Mesocosm Experiments

Using tree-ring crossdating techniques to validate annual growth increments in long-lived fishes

2005 ◽  
Vol 62 (10) ◽  
pp. 2277-2284 ◽  
Author(s):  
Bryan A Black ◽  
George W Boehlert ◽  
Mary M Yoklavich
Keyword(s):  
Time Series ◽  
Tree Ring ◽  
Growth Increment ◽  
Growth Patterns ◽  
Freshwater Species ◽  
Age Validation ◽  
Average Growth ◽  
Growth Increments ◽  
Wide Range ◽  
Ring Analysis

We applied crossdating, a dendrochronology (tree-ring analysis) age validation technique, to growth increment widths of 50 Sebastes diploproa otoliths ranging from 30 to 84 years in age. Synchronous growth patterns were matched by the following: (i) checking the dates of conspicuously narrow growth increments for agreement among samples and (ii) statistically verifying that growth patterns correlated among samples. To statistically verify pattern matching, we fit each time series of otolith measurements with a spline, and all measurements were divided by the values predicted by the curve. This standardized each time series to a mean of 1, removing the effects of age on growth and homogenizing variance. Each time series was then correlated with the average growth patterns of all other series, yielding an average correlation coefficient (r) of 0.53. Average growth of all 50 samples was significantly correlated with an upwelling index (r = 0.40, p = 0.002), the Pacific Decadal Oscillation (r = –0.29, p = 0.007), and the Northern Oscillation Index (r = 0.51, p = 0.0001), corroborating accuracy. We believe this approach to age validation will be applicable to a wide range of long-lived marine and freshwater species.

scholarly journals Biogeochemical feedbacks to ocean acidification in a cohesive photosynthetic sediment

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kay Vopel ◽  
Alexis Marshall ◽  
Shelly Brandt ◽  
Adam Hartland ◽  
Charles K. Lee ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
Coastal Waters ◽  
Metabolic Response ◽  
Sediment Cores ◽  
Biogeochemical Processes ◽  
Ambient Seawater ◽  
Calcite Dissolution ◽  
Sand Control ◽  
Negative Effect ◽  
And Control

AbstractEcosystem feedbacks in response to ocean acidification can amplify or diminish diel pH oscillations in productive coastal waters. Benthic microalgae generate such oscillations in sediment porewater and here we ask how CO2 enrichment (acidification) of the overlying seawater alters these in the absence and presence of biogenic calcite. We placed a 1-mm layer of ground oyster shells, mimicking the arrival of dead calcifying biota (+Calcite), or sand (Control) onto intact silt sediment cores, and then gradually increased the pCO2 in the seawater above half of +Calcite and Control cores from 472 to 1216 μatm (pH 8.0 to 7.6, CO2:HCO3− from 4.8 to 9.6 × 10−4). Porewater [O2] and [H+] microprofiles measured 16 d later showed that this enrichment had decreased the O2 penetration depth (O2-pd) in +Calcite and Control, indicating a metabolic response. In CO2-enriched seawater: (1) sediment biogeochemical processes respectively added and removed more H+ to and from the sediment porewater in darkness and light, than in ambient seawater increasing the amplitude of the diel porewater [H+] oscillations, and (2) in darkness, calcite dissolution in +Calcite sediment decreased the porewater [H+] below that in overlying seawater, reversing the sediment–seawater H+ flux and decreasing the amplitude of diel [H+] oscillations. This dissolution did not, however, counter the negative effect of CO2 enrichment on O2-pd. We now hypothesise that feedback to CO2 enrichment—an increase in the microbial reoxidation of reduced solutes with O2—decreased the sediment O2-pd and contributed to the enhanced porewater acidification.

scholarly journals Biogeochemical Feedbacks to Ocean Acidification in a Cohesive Photosynthetic Sediment

2021 ◽  
Author(s):  
Kay Vopel ◽  
Alexis Marshall ◽  
Shelly Brandt ◽  
Adam Hartland ◽  
Charles K Lee ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
Coastal Waters ◽  
Metabolic Response ◽  
Sediment Cores ◽  
Ambient Seawater ◽  
Dark Light ◽  
Sand Control ◽  
Negative Effect ◽  
And Control ◽  
Do So

Abstract Ecosystem feedbacks in response to ocean acidification can amplify or diminish the diel pH oscillations that characterize productive coastal waters. We report that benthic microalgae generate such oscillations in the porewater of cohesive sediment and ask how carbonation (acidification) of the overlying seawater alters these in the absence and presence of biogenic calcite. To do so, we placed a 1-mm layer of ground oyster shells (Treatment) or sand (Control) onto intact sediment cores free of large dwelling fauna, and then gradually increased the pCO2 in the seawater above half of the Treatment and Control cores from 472 to 1216 μatm (pH 8.0 to 7.6, CO2:HCO3- from 4.8 to 9.6 x 10-4). Vertical porewater [O2] and [H+] microprofiles measured 16 d later showed that this carbonation had decreased O2 penetration in all cores, indicating a metabolic response. In carbonated seawater: (1) sediment biogeochemical processes added and removed more H+ to and from the porewater in darkness and light, respectively, than in ambient seawater increasing the amplitude of the dark–light porewater [H+] oscillations, and (2) the dissolution of calcite decreased the porewater [H+] below that in overlying seawater, reversing the dark sediment–seawater H+ flux and decreasing the amplitude of diel [H+] oscillations. This dissolution did not, however, counter the negative effect of carbonation on sediment O2 penetration. We hypothesise that the latter effect and the observed enhanced acidification of the sediment porewater were caused by an ecosystem feedback: a CO2-induced increase in the microbial reoxidation of reduced solutes with O2.

scholarly journals Semi-automated open water iceberg detection from Landsat applied to Disko Bay, West Greenland

2019 ◽  
Vol 65 (251) ◽  
pp. 468-480 ◽  
Author(s):  
JESSICA SCHEICK ◽  
ELLYN M. ENDERLIN ◽  
GORDON HAMILTON
Keyword(s):  
Machine Learning ◽  
Time Series ◽  
Power Law ◽  
Coastal Waters ◽  
Landsat Imagery ◽  
Open Water ◽  
Size Distributions ◽  
Negative Power ◽  
West Greenland ◽  
Cloud Mask

ABSTRACTChanges in Greenland's marine-terminating outlet glaciers have led to changes in the flux of icebergs into Greenland's coastal waters, yet icebergs remain a relatively understudied component of the ice-ocean system. We developed a simple iceberg delineation algorithm for Landsat imagery. A machine learning-based cloud mask incorporated into the algorithm enables us to extract iceberg size distributions from open water even in partially cloudy scenes. We applied the algorithm to the Landsat archive covering Disko Bay, West Greenland, to derive a time series of iceberg size distributions from 2000–02 and 2013–15. The time series captures a change in iceberg size distributions, which we interpret as a result of changes in the calving regime of the parent glacier, Sermeq Kujalleq (Jakobshavn Isbræ). The change in calving style associated with the disintegration and disappearance of Sermeq Kujalleq's floating ice tongue resulted in the production of more small icebergs. The increased number of small icebergs resulted in increasingly negative power law slopes fit to iceberg size distributions in Disko Bay, suggesting that iceberg size distribution time series provide useful insights into changes in calving dynamics.

Fish age validation by Radiometric analysis of Otoliths

1992 ◽  
Vol 43 (5) ◽  
pp. 913 ◽  
Author(s):  
GE Fenton ◽  
SA Short
Keyword(s):  
Data Analysis ◽  
Radiochemical Analysis ◽  
Age Validation ◽  
Radiometric Analysis ◽  
History Of ◽  
Natural Isotopes ◽  
Fish Otoliths

Radiochemical analysis of aragonitic fish otoliths provides a useful approach to validating ages obtained by more common methods. The history of applications of radiometry using short-lived natural isotopes to clams, Nautilus, living corals and fish otoliths is briefly reviewed. The biogeochemical assumptions required for successful use of these techniques are discussed, and the appropriate mathematical treatments required for data analysis are outlined. Novel normalization techniques designed to widen the validity of this approach are proposed. Desirable lines of further research are also briefly discussed.

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