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Pervasive and sustained coral diseases contribute to the systemic degradation of reef ecosystems, however, to date an understanding of the physicochemical controls on a coral disease event is still largely lacking. Water circulation and residence times and submarine groundwater discharge (SGD) all determine the degree to which reef organisms are exposed to the variable chemistry of overlying waters; understanding these physical controls is thus necessary to interpret spatial patterns in coral health. The recent discovery of coral Black Band Disease at Mākua Reef on Kaua‘i, Hawai‘i prompted an investigation into the physicochemical drivers and geomorphic controls of reef water circulation, and the temporally variable nutrient fluxes derived from SGD. Results reveal localized stagnant water parcels at Mākua Reef where groundwater-derived high nutrient loading and low salinities act in concert as stressors to coralline health – and where Black Band Disease was uniquely identified. The observed high nutrient levels during low tide conditions are likely associated with nearby upstream cesspools and drain fields. Information obtained using such a multidisciplinary approach has direct value for successful management of coastal aquifers and the health and sustainability of adjacent nearshore coral reef ecosystems.
Ferdinand K. J. Oberle; Curt D. Storlazzi; Olivia M. Cheriton; Renee K. Takesue; Daniel J. Hoover; Joshua B. Logan; Christina Runyon; Christina A. Kellogg; Cordell D. Johnson; Peter W. Swarzenski. Physicochemical Controls on Zones of Higher Coral Stress Where Black Band Disease Occurs at Mākua Reef, Kaua‘i, Hawai‘i. Frontiers in Marine Science 2019, 6, 1 .
AMA StyleFerdinand K. J. Oberle, Curt D. Storlazzi, Olivia M. Cheriton, Renee K. Takesue, Daniel J. Hoover, Joshua B. Logan, Christina Runyon, Christina A. Kellogg, Cordell D. Johnson, Peter W. Swarzenski. Physicochemical Controls on Zones of Higher Coral Stress Where Black Band Disease Occurs at Mākua Reef, Kaua‘i, Hawai‘i. Frontiers in Marine Science. 2019; 6 ():1.
Chicago/Turabian StyleFerdinand K. J. Oberle; Curt D. Storlazzi; Olivia M. Cheriton; Renee K. Takesue; Daniel J. Hoover; Joshua B. Logan; Christina Runyon; Christina A. Kellogg; Cordell D. Johnson; Peter W. Swarzenski. 2019. "Physicochemical Controls on Zones of Higher Coral Stress Where Black Band Disease Occurs at Mākua Reef, Kaua‘i, Hawai‘i." Frontiers in Marine Science 6, no. : 1.
Arctic permafrost stores vast amounts of methane (CH4) in subsurface reservoirs. Thawing permafrost creates areas for this potent greenhouse gas to be released to the atmosphere. Identifying ‘hot spots’ of methane flux on a local scale has been limited by the spatial scales of traditional ground-based or satellite-based methane-sampling methods. Here we present a reliable and an easily replicable design using only off-the-shelf, cost-effective methane sensor components and an Unmanned Aerial System (UAS). Our results demonstrate the high efficiency of the design and the advantages of this methodology for environmental methane studies that are subjected to the high spatial variability of methane levels. On Barter Island, NE Alaska, we noted spikes in CH4 concentrations coincident with topographic features or anomalies. Such spikes may be attributed to enhanced land/air transfer and may reveal zones of high methane production and/or minimal oxidation in areas of thermoerosional gullies along thawing coastal zones. Thermoerosional gullies represent hotspots that release significantly higher levels of methane than the surrounding areas, thus suggesting that point sampling is inadequate in characterizing methane releases and that increasing rates of permafrost thaw may result in increasing point sources of high CH4 emissions.
Ferdinand K. J. Oberle; Ann E. Gibbs; Bruce M. Richmond; Li H. Erikson; Mark P. Waldrop; Peter W. Swarzenski. Towards determining spatial methane distribution on Arctic permafrost bluffs with an unmanned aerial system. SN Applied Sciences 2019, 1, 236 .
AMA StyleFerdinand K. J. Oberle, Ann E. Gibbs, Bruce M. Richmond, Li H. Erikson, Mark P. Waldrop, Peter W. Swarzenski. Towards determining spatial methane distribution on Arctic permafrost bluffs with an unmanned aerial system. SN Applied Sciences. 2019; 1 (3):236.
Chicago/Turabian StyleFerdinand K. J. Oberle; Ann E. Gibbs; Bruce M. Richmond; Li H. Erikson; Mark P. Waldrop; Peter W. Swarzenski. 2019. "Towards determining spatial methane distribution on Arctic permafrost bluffs with an unmanned aerial system." SN Applied Sciences 1, no. 3: 236.
Natural and human-induced seabed sediment disturbances affect wide areas of the global coastal ocean. These recurrent to chronic disturbances mobilize significant amounts of material, including substances that have the potential to significantly harm the environment once re-released. This very challenging issue is difficult to deal with if sub-surface contaminant concentrations are unknown. Based on the analysis of 11 new, up to 5-m long sediment cores taken offshore in the Gulf of Cadiz, the contamination history (using the trace elements lead and zinc) is well documented over major parts of the gulf. Ore mining and metal processing industries on the southwestern Iberian Peninsula started five thousand years ago and experienced a first peak during the Roman Period, which can be detected over the entire gulf. The Industrial Era added a massive, shelf-wide heavy metal excursion of unprecedented dimension. This metal contamination to the coastal ocean decreased in the 1990s and appears to be today limited to larger areas off the Tinto/Odiel and Guadiana River mouths. The unforeseen, significant finding of this study is that the gulf-wide, peak heavy metal concentration, stemming from the Industrial Era, is widely overlain by a modern sediment veneer just thick enough to cover the contaminant horizon, but thin enough to have this layer within the reach of natural or human-induced sediment mobilization events.
Till J.J. Hanebuth; Mary Lee King; Isabel Mendes; Susana Lebreiro; Francisco J. Lobo; Ferdinand Oberle; Laura Antón; Paulo Alves Ferreira; Maria Isabel Reguera. Hazard potential of widespread but hidden historic offshore heavy metal (Pb, Zn) contamination (Gulf of Cadiz, Spain). Science of The Total Environment 2018, 637-638, 561 -576.
AMA StyleTill J.J. Hanebuth, Mary Lee King, Isabel Mendes, Susana Lebreiro, Francisco J. Lobo, Ferdinand Oberle, Laura Antón, Paulo Alves Ferreira, Maria Isabel Reguera. Hazard potential of widespread but hidden historic offshore heavy metal (Pb, Zn) contamination (Gulf of Cadiz, Spain). Science of The Total Environment. 2018; 637-638 ():561-576.
Chicago/Turabian StyleTill J.J. Hanebuth; Mary Lee King; Isabel Mendes; Susana Lebreiro; Francisco J. Lobo; Ferdinand Oberle; Laura Antón; Paulo Alves Ferreira; Maria Isabel Reguera. 2018. "Hazard potential of widespread but hidden historic offshore heavy metal (Pb, Zn) contamination (Gulf of Cadiz, Spain)." Science of The Total Environment 637-638, no. : 561-576.
Groundwater resources of low-lying atoll islands are threatened due to short-term and long-term changes in rainfall, wave climate, and sea level. A better understanding of how these forcings affect the limited groundwater resources was explored on Roi-Namur in the Republic of the Marshall Islands. As part of a 16-month study, a rarely recorded island-overwash event occurred and the island’s aquifer’s response was measured. The findings suggest that small-scale overwash events cause an increase in salinity of the freshwater lens that returns to pre-overwash conditions within one month. The overwash event is addressed in the context of climate-related local sea-level change, which suggests that overwash events and associated degradations in freshwater resources are likely to increase in severity in the future due to projected rises in sea level. Other forcings, such as severe rainfall events, were shown to have caused a sudden freshening of the aquifer, with salinity levels retuning to pre-rainfall levels within three months. Tidal forcing of the freshwater lens was observed in electrical resistivity profiles, high-resolution conductivity, groundwater-level well measurements and through submarine groundwater discharge calculations. Depth-specific geochemical pore water measurements further assessed and confirmed the distinct boundaries between fresh and saline water masses in the aquifer. The identification of the freshwater lens’ saline boundaries is essential for a quantitative evaluation of the aquifers freshwater resources and help understand how these resources may be impacted by climate change and anthropogenic activities.
Ferdinand K. J. Oberle; Peter W. Swarzenski; Curt D. Storlazzi. Atoll Groundwater Movement and Its Response to Climatic and Sea-Level Fluctuations. Water 2017, 9, 650 .
AMA StyleFerdinand K. J. Oberle, Peter W. Swarzenski, Curt D. Storlazzi. Atoll Groundwater Movement and Its Response to Climatic and Sea-Level Fluctuations. Water. 2017; 9 (9):650.
Chicago/Turabian StyleFerdinand K. J. Oberle; Peter W. Swarzenski; Curt D. Storlazzi. 2017. "Atoll Groundwater Movement and Its Response to Climatic and Sea-Level Fluctuations." Water 9, no. 9: 650.
Unlike the major anthropogenic changes that terrestrial and coastal habitats underwent during the last centuries such as deforestation, river engineering, agricultural practices or urbanism, those occurring underwater are veiled from our eyes and have continued nearly unnoticed. Only recent advances in remote sensing and deep marine sampling technologies have revealed the extent and magnitude of the anthropogenic impacts to the seafloor. In particular, bottom trawling, a fishing technique consisting of dragging a net and fishing gear over the seafloor to capture bottom-dwelling living resources has gained attention among the scientific community, policy makers and the general public due to its destructive effects on the seabed. Trawling gear produces acute impacts on biota and the physical substratum of the seafloor by disrupting the sediment column structure, overturning boulders, resuspending sediments and imprinting deep scars on muddy bottoms. Also, the repetitive passage of trawling gear over the same areas creates long-lasting, cumulative impacts that modify the cohesiveness and texture of sediments. It can be asserted nowadays that due to its recurrence, mobility and wide geographical extent, industrial trawling has become a major force driving seafloor change and affecting not only its physical integrity on short spatial scales but also imprinting measurable modifications to the geomorphology of entire continental margins.
Ferdinand K. J. Oberle; Pere Puig; Jacobo Martín. Fishing Activities. Submarine Geomorphology 2017, 503 -534.
AMA StyleFerdinand K. J. Oberle, Pere Puig, Jacobo Martín. Fishing Activities. Submarine Geomorphology. 2017; ():503-534.
Chicago/Turabian StyleFerdinand K. J. Oberle; Pere Puig; Jacobo Martín. 2017. "Fishing Activities." Submarine Geomorphology , no. : 503-534.
Benjamin Baasch; Hendrik Müller; Tilo Von Dobeneck; Ferdinand K.J. Oberle. Determination of grain-size characteristics from electromagnetic seabed mapping data: A NW Iberian shelf study. Continental Shelf Research 2017, 140, 75 -83.
AMA StyleBenjamin Baasch, Hendrik Müller, Tilo Von Dobeneck, Ferdinand K.J. Oberle. Determination of grain-size characteristics from electromagnetic seabed mapping data: A NW Iberian shelf study. Continental Shelf Research. 2017; 140 ():75-83.
Chicago/Turabian StyleBenjamin Baasch; Hendrik Müller; Tilo Von Dobeneck; Ferdinand K.J. Oberle. 2017. "Determination of grain-size characteristics from electromagnetic seabed mapping data: A NW Iberian shelf study." Continental Shelf Research 140, no. : 75-83.
Thomas D. Lorenson; Christopher H. Conaway; John Fitzpatrick; Doug Choy; Ferdinand Oberle; Cordell Johnson; Bruce Richmond; Ann Gibbs; Peter W. Swarzenski. CHEMISTRY OF CRYOPEGS ON BARTER ISLAND, NORTH SLOPE ALASKA. GSA Annual Meeting in Seattle, Washington, USA - 2017 2017, 1 .
AMA StyleThomas D. Lorenson, Christopher H. Conaway, John Fitzpatrick, Doug Choy, Ferdinand Oberle, Cordell Johnson, Bruce Richmond, Ann Gibbs, Peter W. Swarzenski. CHEMISTRY OF CRYOPEGS ON BARTER ISLAND, NORTH SLOPE ALASKA. GSA Annual Meeting in Seattle, Washington, USA - 2017. 2017; ():1.
Chicago/Turabian StyleThomas D. Lorenson; Christopher H. Conaway; John Fitzpatrick; Doug Choy; Ferdinand Oberle; Cordell Johnson; Bruce Richmond; Ann Gibbs; Peter W. Swarzenski. 2017. "CHEMISTRY OF CRYOPEGS ON BARTER ISLAND, NORTH SLOPE ALASKA." GSA Annual Meeting in Seattle, Washington, USA - 2017 , no. : 1.
Ferdinand K.J. Oberle; Curt D. Storlazzi; Till Hanebuth. What a drag: Quantifying the global impact of chronic bottom trawling on continental shelf sediment. Journal of Marine Systems 2016, 159, 109 -119.
AMA StyleFerdinand K.J. Oberle, Curt D. Storlazzi, Till Hanebuth. What a drag: Quantifying the global impact of chronic bottom trawling on continental shelf sediment. Journal of Marine Systems. 2016; 159 ():109-119.
Chicago/Turabian StyleFerdinand K.J. Oberle; Curt D. Storlazzi; Till Hanebuth. 2016. "What a drag: Quantifying the global impact of chronic bottom trawling on continental shelf sediment." Journal of Marine Systems 159, no. : 109-119.
Till J.J. Hanebuth; Wenyan Zhang; Ferdinand K. Oberle; Yongsheng Cui; Ana I. Santos. MUD DEPOCENTERS ON CONTINENTAL SHELVES AND STORM-DRIVEN BOTTOM TRANSPORT CONTROLLING THEIR FORMATION. 65th Annual Southeastern GSA Section Meeting 2016, 1 .
AMA StyleTill J.J. Hanebuth, Wenyan Zhang, Ferdinand K. Oberle, Yongsheng Cui, Ana I. Santos. MUD DEPOCENTERS ON CONTINENTAL SHELVES AND STORM-DRIVEN BOTTOM TRANSPORT CONTROLLING THEIR FORMATION. 65th Annual Southeastern GSA Section Meeting. 2016; ():1.
Chicago/Turabian StyleTill J.J. Hanebuth; Wenyan Zhang; Ferdinand K. Oberle; Yongsheng Cui; Ana I. Santos. 2016. "MUD DEPOCENTERS ON CONTINENTAL SHELVES AND STORM-DRIVEN BOTTOM TRANSPORT CONTROLLING THEIR FORMATION." 65th Annual Southeastern GSA Section Meeting , no. : 1.
Widespread bottom trawling on the NW Iberian shelf causes chronic sediment and habitat disturbance. The few studies that have investigated vessel-modified sedimentary-structure and texture of the seabed have typically classified their results as being either impacted by trawling or not. This study indicates that bottom trawling can result in a sequence of vastly different effects to the lithology of seabed sediment, which have in turn different ecological consequences. Here, we combined very high-resolution spatial bottom-trawling data with sedimentological (grain size, porosity) and geochemical datasets (excess 210Pb, 3D petroleum fingerprinting) to study sediment disturbance, including sorting and mixing. Our results were used to develop five conceptual disturbance scenarios: minimal seabed effects, sediment overturning, complete sediment mixing, sediment grading and layering, and loss of sediment. Considering that bottom trawling is a widespread and growing global fishing technique, such impacts need to be considered in the management of habitat conservation as well as in the reconstruction of late Holocene climate history from shallow-water deposits, not just on the NW Iberian shelf, but also globally.
Ferdinand Oberle; Peter W. Swarzenski; Christopher M. Reddy; Robert Nelson; Benjamin Baasch; Till J.J. Hanebuth. Deciphering the lithological consequences of bottom trawling to sedimentary habitats on the shelf. Journal of Marine Systems 2015, 159, 120 -131.
AMA StyleFerdinand Oberle, Peter W. Swarzenski, Christopher M. Reddy, Robert Nelson, Benjamin Baasch, Till J.J. Hanebuth. Deciphering the lithological consequences of bottom trawling to sedimentary habitats on the shelf. Journal of Marine Systems. 2015; 159 ():120-131.
Chicago/Turabian StyleFerdinand Oberle; Peter W. Swarzenski; Christopher M. Reddy; Robert Nelson; Benjamin Baasch; Till J.J. Hanebuth. 2015. "Deciphering the lithological consequences of bottom trawling to sedimentary habitats on the shelf." Journal of Marine Systems 159, no. : 120-131.
Ferdinand Oberle; Curt D. Storlazzi; Till J.J. Hanebuth. Wave-driven sediment mobilization on a storm-controlled continental shelf (Northwest Iberia). Journal of Marine Systems 2014, 139, 362 -372.
AMA StyleFerdinand Oberle, Curt D. Storlazzi, Till J.J. Hanebuth. Wave-driven sediment mobilization on a storm-controlled continental shelf (Northwest Iberia). Journal of Marine Systems. 2014; 139 ():362-372.
Chicago/Turabian StyleFerdinand Oberle; Curt D. Storlazzi; Till J.J. Hanebuth. 2014. "Wave-driven sediment mobilization on a storm-controlled continental shelf (Northwest Iberia)." Journal of Marine Systems 139, no. : 362-372.
Ferdinand Oberle; Till J.J. Hanebuth; Benjamin Baasch; Tilmann Schwenk. Volumetric budget calculation of sediment and carbon storage and export for a late Holocene mid-shelf mudbelt system (NW Iberia). Continental Shelf Research 2014, 76, 12 -24.
AMA StyleFerdinand Oberle, Till J.J. Hanebuth, Benjamin Baasch, Tilmann Schwenk. Volumetric budget calculation of sediment and carbon storage and export for a late Holocene mid-shelf mudbelt system (NW Iberia). Continental Shelf Research. 2014; 76 ():12-24.
Chicago/Turabian StyleFerdinand Oberle; Till J.J. Hanebuth; Benjamin Baasch; Tilmann Schwenk. 2014. "Volumetric budget calculation of sediment and carbon storage and export for a late Holocene mid-shelf mudbelt system (NW Iberia)." Continental Shelf Research 76, no. : 12-24.
Electromagnetic induction (EMI) methods are widely used on land to map electric conductivity and/or magnetic susceptibility distributions of surficial sediments. In contrast, the application of these methods in marine environments is relatively novel. Based on the recently developed electromagnetic benthic profiler MARUM-NERIDIS III we investigate the potential of concentric-loop EMI methods to recover conductivity and susceptibility of layered marine sediments. Sensitivity analyses based on a data and model normalized Jacobian matrix were performed to compare the influence of conductivity and susceptibility to in-phase and quadrature components at different frequencies. Both parameters substantially affect the EM response. However, the influence of susceptibility decreases more with depth and offers lower depth resolution than that of conductivity. A 1-D inversion algorithm to reconstruct vertical conductivity distributions was developed from existing non-linear inversion methods using apparent conductivity and apparent susceptibility recovered from simultaneous half-space inversion as a priori information. This algorithm was tested on synthetic and real marine EM data from a commercial multifrequency concentric loop EMI system (GEM-3). The results indicate that our inversion algorithm yields meaningful results down to approximately 3 m depth under typical shallow marine conditions. The comparison of inversion results recovered with 1-D and 2-D constraints showed that combining lateral with vertical constraints substantially improves the resolution of the inversion outputs. Field data from the NW Iberian shelf was calibrated according to a processing flow specifically designed for underwater conditions and analysed. Inversion outputs are in good agreement with ground-truthing stratigraphic investigations and deliver relevant clues on past and present sediment dynamics.
B. Baasch; H. Müller; F. K. J. Oberle; T. Von Dobeneck. Inversion of marine multifrequency electromagnetic profiling data: a new approach to resolve surficial sediment stratification. Geophysical Journal International 2014, 200, 439 -451.
AMA StyleB. Baasch, H. Müller, F. K. J. Oberle, T. Von Dobeneck. Inversion of marine multifrequency electromagnetic profiling data: a new approach to resolve surficial sediment stratification. Geophysical Journal International. 2014; 200 (1):439-451.
Chicago/Turabian StyleB. Baasch; H. Müller; F. K. J. Oberle; T. Von Dobeneck. 2014. "Inversion of marine multifrequency electromagnetic profiling data: a new approach to resolve surficial sediment stratification." Geophysical Journal International 200, no. 1: 439-451.