62 research outputs found
Case studies in coral restoration: assessing life history and longterm survival patterns in restoration outplants of Acropora cervicornis (Staghorn Coral) and Acropora palmata (Elkhorn Coral) in the Florida Keys and Belize
This thesis is composed of two articles. The first is an analysis of long-term survival among A. cervicornis outplants in the Florida Keys, from 2007 to the present. The second is a review of literature that informs coral restoration and guides both restoration practitioners and coral researchers towards greater effectiveness in outplant survival and understanding biological processes involved in restoration.
In the first article, despite promising initial evidence of outplant survival and health, the long-term results, using Weibull survival analysis, are discouraging with almost all out planted corals over an 8 year long study exhibiting steep declines in percent live tissue and survival between three and five years. Not only is this 3-5 year collapse apparent in all the outplanted cohorts, but the evidence is highly significant that the length of outplant survival is decreasing with each passing year (diminished resilience). These findings suggest that some shared, likely environmental factor, is increasingly impacting all outplants. Further, no cohorts appear to adapt to the environmental conditions in which these declines are occurring (diminished adaptive capacity), a trend that would be evident if their declines slowed or reversed and Weibull beta-parameterization would show.
The second article, reviews several areas of recent study which offer avenues for future research: these include, ecological history and biogeography, developmental pathways of colonial form and function, polarity and symmetry, genetics, wound healing, fecundity, reproduction, sexual maturity and community interactions. The thesis concludes with questions for further research and understanding in the field of coral restoration
Japan Tsunami Current Flows Observed by HF Radars on Two Continents
Quantitative real-time observations of a tsunami have been limited to deep-water, pressure-sensor observations of changes in the sea surface elevation and observations of sea level fluctuations at the coast, which are essentially point measurements. Constrained by these data, models have been used for predictions and warning of the arrival of a tsunami, but to date no detailed verification of flow patterns nor area measurements have been possible. Here we present unique HF-radar area observations of the tsunami signal seen in current velocities as the wave train approaches the coast. Networks of coastal HF-radars are now routinely observing surface currents in many countries and we report clear results from five HF radar sites spanning a distance of 8,200 km on two continents following the magnitude 9.0 earthquake off Sendai, Japan, on 11 March 2011. We confirm the tsunami signal with three different methodologies and compare the currents observed with coastal sea level fluctuations at tide gauges. The distance offshore at which the tsunami can be detected, and hence the warning time provided, depends on the bathymetry: the wider the shallow continental shelf, the greater this time. Data from these and other radars around the Pacific rim can be used to further develop radar as an important tool to aid in tsunami observation and warning as well as post-processing comparisons between observation and model predictions
The circulation and water masses in the Gulf of the Farallones
Six ADCP and CTD ship surveys of the continental shelf and slope in the vicinity of the Gulf
of the Farallones, CA, were conducted in 1990}1992. ADCP data provide much more detail on
the structure of the currents over the slope and shelf in the Gulf and reveal a persistent, largely
barotropic poleward #ow with a complex mesoscale #ow "eld superimposed. The directly
measured currents are not well represented by the geostrophic velocity "elds derived from
hydrographic casts. Important upper-ocean circulation features include: a Slope Countercurrent
(SCC), variable shelf circulation, and submesoscale eddy-like features. The SCC was present in
all seasons and is believed due to a strong year-round positive wind-stress curl enhanced by
Point Reyes. Its #ow was poleward throughout the upper 300 m, and often surface intensi"ed.
Poleward transport in the upper 400 m was 1}3 Sv, much greater than previous geostrophic
estimates for the California Current System constrained to a 500 dbar reference level. The shelf
circulation was much more variable than the SCC and generally exhibited a pattern consistent
with classic Ekman dynamics, responding to synoptic wind forcing. Submesoscale vortices, or
eddies, often dominated the general #ow "eld. These eddies are thought to be generated by the
frictional torque associated with current}topography interactions. Their centers typically have
a distinct water type associated with either the SCC or the southward-#owing California
Current. Higher spiciness anomalies, representing a higher percentage of Paci"c Equatorial Water (PEW), were typically found in the core of the SCC or within anticyclonic eddies. Lower
(bland) spiciness anomalies, characteristic of a higher percentage of Paci"c Subarctic Water
(PSAW), were associated with cyclonic eddies. While these circulation features were largely
barotropic, the #ow also adjusted baroclinically to changes in the density "eld, as di!erent
water types were advected by the general #ow "eld or by mesoscale instabilities in the
large-scale boundary currents as they interacted with topography. Despite a seasonal cycle in
regional wind and ocean temperature time series, there is no obvious seasonal pattern in the
circulation. Most of the temporal variability in the current appears to be due to synoptic and
interannual variations in atmospheric forcing. Because of the very dynamic three-dimensional
nature of the regional circulation, the Gulf of the Farallones is likely to be a center for active
mixing and exchange between the coastal and California Current waters, relative to most US
west coast locales
Evaluating Connectivity between Marine Protected Areas Using CODAR High-Frequency Radar
To investigate the connectivity between central California marine protected areas (MPAs), back-projections were calculated using the network of high-frequency (HF) radar ocean surface current mapping stations operated along the California coast by the member institutions of the Coastal Ocean Currents Monitoring Program with funding provided by California voters through Propositions 40 & 50 and administered by the State Coastal Conservancy. Trajectories of 1 km resolution grids of water particles were back-projected from ten MPAs each hour, out through 40 days in the past, from each day in 2008, producing a map of where surface waters travel over a 40-day period to reach the MPAs - and visualizations of the length of time the waters travel along these paths. By comparing the travel times of those back-projected track-points that crossed between MPA regions, the connection time between MPAs along the State\u27s central coast was assessed. Repeating these calculations resulted in a connectivity matrix between the MPAs in the region, and may be useful for assessing connectivity for the important invertebrate and fish larvae that are restricted to the surface ocean during a fraction of their lifecycle
Poleward propagating subinertial alongshore surface currents off the U.S. West Coast
The article of record as published may be found at http://dx.doi.org/10.1002/jgrc.20400The network comprising 61 high-frequency radar systems along the U.S. West Coast
(USWC) provides a unique, high resolution, and broad scale view of ocean surface
circulation. Subinertial alongshore surface currents show poleward propagating signals with
phase speeds of O(10) and O(100–300) km d 1 that are consistent with historical in situ
observations off the USWC and that can be possibly interpreted as coastally trapped waves
(CTWs). The propagating signals in the slow mode are partly observed in southern
California, which may result from scattering and reflection of higher-mode CTWs due to
curvature of shoreline and bathymetry near Point Conception, California. On the other hand,
considering the order of the phase speed in the slow mode, the poleward propagating signals
may be attributed to alongshore advection or pressure-driven flows. A statistical regression
of coastal winds at National Data Buoy Center buoys on the observed surface currents
partitions locally and remotely wind-forced components, isolates footprints of the
equatorward propagating storm events in winter off the USWC, and shows the poleward
propagating signals year round.National Research Foundation (NRF)Ministry of EducationHuman Resources Development of the Korea Institute of Energy Technology Evaluation and Planning (KETEP)Ministry of Trade, Industry and EnergyRepublic of Koreano. 2013R1A1A2057849no. 2011403020004
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Poleward propagating subinertial alongshore surface currents off the U.S. West Coast
The network comprising 61 high-frequency radar systems along the U.S. West Coast (USWC) provides a unique, high resolution, and broad scale view of ocean surface circulation. Subinertial alongshore surface currents show poleward propagating signals with phase speeds of O(10) and O(100–300) km d⁻¹ that are consistent with historical in situ observations off the USWC and that can be possibly interpreted as coastally trapped waves (CTWs). The propagating signals in the slow mode are partly observed in southern California, which may result from scattering and reflection of higher-mode CTWs due to curvature of shoreline and bathymetry near Point Conception, California. On the other hand, considering the order of the phase speed in the slow mode, the poleward propagating signals may be attributed to alongshore advection or pressure-driven flows. A statistical regression of coastal winds at National Data Buoy Center buoys on the observed surface currents partitions locally and remotely wind-forced components, isolates footprints of the equatorward propagating storm events in winter off the USWC, and shows the poleward propagating signals year round.This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)2169-9291.Keywords: wind transfer function, surface currents, coastally trapped waves, high-frequency radar, poleward propagation, phase spee
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Mapping the U.S. West Coast surface circulation: A multiyear analysis of high‐frequency radar observations
The nearly completed U.S. West Coast (USWC) high-frequency radar (HFR) network provides an unprecedented capability to monitor and understand coastal ocean dynamics and phenomenology through hourly surface current measurements at up to 1 km resolution. The dynamics of the surface currents off the USWC are governed by tides, winds, Coriolis force, low-frequency pressure gradients (less than 0.4 cycles per day (cpd)), and nonlinear interactions of those forces. Alongshore surface currents show poleward propagating signals with phase speeds of O(10) and O(100 to 300) km day⁻¹ and time scales of 2 to 3 weeks. The signals with slow phase speed are only observed in southern California. It is hypothesized that they are scattered and reflected by shoreline curvature and bathymetry change and do not penetrate north of Point Conception. The seasonal transition of alongshore surface circulation forced by upwelling-favorable winds and their relaxation is captured in fine detail. Submesoscale eddies, identified using flow geometry, have Rossby numbers of 0.1 to 3, diameters in the range of 10 to 60 km, and persistence for 2 to 12 days. The HFR surface currents resolve coastal surface ocean variability continuously across scales from submesoscale to mesoscale (O(1) km to O(1000) km). Their spectra decay with k⁻² at high wave number (less than 100 km) in agreement with theoretical submesoscale spectra below the observational limits of present-day satellite altimeters.This is the publisher's final pdf. The published article is copyrighted by American Geophysical Union and can be found at: http://www.agu.org/journals/jc/index.shtm
The twilight of the Liberal Social Contract? On the Reception of Rawlsian Political Liberalism
This chapter discusses the Rawlsian project of public reason, or public justification-based 'political' liberalism, and its reception. After a brief philosophical rather than philological reconstruction of the project, the chapter revolves around a distinction between idealist and realist responses to it. Focusing on political liberalism’s critical reception illuminates an overarching question: was Rawls’s revival of a contractualist approach to liberal legitimacy a fruitful move for liberalism and/or the social contract tradition? The last section contains a largely negative answer to that question. Nonetheless the chapter's conclusion shows that the research programme of political liberalism provided and continues to provide illuminating insights into the limitations of liberal contractualism, especially under conditions of persistent and radical diversity. The programme is, however, less receptive to challenges to do with the relative decline of the power of modern states
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