David W Hastings

Eckerd College · Marine Science

Deep-sea offshore northwestern Cuba is the less studied zone of the Gulf of Mexico (GoM). Our study aimed to set an environmental baseline and investigate a potential west-east gradient of sediment properties and nematode diversity along the northwestern Cuba. Sediments were collected by multicorer at nine sites in the insular slope between 974 and...

Marine Oil Snow Sedimentation and Flocculent Accumulation (MOSSFA) refers to the process of formation, sinking, and seafloor deposition of oil-contaminated marine snow and oil-mineral aggregates. MOSSFA was well documented in the northern Gulf of Mexico (GoM) in the aftermath of the Deepwater Horizon (DWH 2010) and likely occurred in the southern G...

Following the blowout of the Macondo well, a sedimentation pulse resulted in significant changes in sedimentary redox conditions. This is demonstrated by downcore and temporal changes in the concentration of redox-sensitive metals: Mn and Re. Sediment cores collected in the NE Gulf of Mexico reveal increased sedimentation after the Deepwater Horizo...

The microbial ecology of oligotrophic deep ocean sediments is understudied relative to their shallow counterparts, and this lack of understanding hampers our ability to predict responses to current and future perturbations. The Gulf of Mexico has experienced two of the largest accidental marine oil spills, the 1979 Ixtoc‐1 blowout and the 2010 Deep...

The microbial ecology of oligotrophic deep ocean sediments is understudied relative to their shallow counterparts, and this lack of understanding hampers our ability to predict responses to current and future perturbations. The Gulf of Mexico has experienced two of the largest accidental marine oil spills, i.e., the 1979 Ixtoc-1 blowout in the Sout...

Sediments were recovered from the mid-bay portion of the Chesapeake Bay when bottom water conditions were sulfidic. Metal concentrations (Fe, Mn, Ba, V, Ni, Cu, Co, Cd, Mo, U, and Re) were determined in both pore waters and solid phase samples, which were determined using total and nitric acid digestion (EPA 3051a) methods. V, Cr, and Ni were prefe...

Following the Deepwater Horizon (DWH) event in 2010 subsurface hydrocarbon intrusions (1000-1300 m) and an order of magnitude increase in flocculent hydrocarbon deposition caused increased concentrations of hydrocarbons in continental slope sediments. This study sought to characterize the variability [density, Fisher's alpha (S), equitability (E),...

Aquatic sediment core subsampling is commonly performed at cm or half-cm resolution. Depending on the sedimentation rate and depositional environment, this resolution provides records at the annual to decadal scale, at best. An extrusion method, using a calibrated, threaded-rod is presented here, which allows for millimeter-scale subsampling of aqu...

A series of sediment cores collected from the Gulf of Mexico (2010-2014) were used to assess the spatial and temporal impacts on the benthos, quantify the recovery of benthic foraminiferal (BF) community and shell chemistry (δ13C) following the Deepwater Horizon (DWH) event. A significant decline in BF density (80-93%) and diversity recognized sinc...

The objective of this study was to investigate the impacts of the Deepwater Horizon (DWH) oil discharge at the seafloor as recorded in bottom sediments of the DeSoto Canyon region in the northeastern Gulf of Mexico. Through a close coupling of sedimentological, geochemical, and biological approaches, multiple independent lines of evidence from 11 s...

The Deepwater Horizon (DWH) spill released 4.9 million barrels of oil into the Gulf of Mexico (GoM) over 87 days. Sediment and water sampling efforts were concentrated SW of the DWH and in coastal areas. Here we present geochemistry data from sediment cores collected in the aftermath of the DWH event from 1000 - 1500 m water depth in the DeSoto Can...

Sediment cores were collected from three sites (1000–1200 m water depth) in the northeastern Gulf of Mexico from December 2010 to June 2011 to assess changes in benthic fo-raminiferal density related to the Deepwater Horizon (DWH) event (April-July 2010, 1500 m water depth). Short-lived radioisotope geochronologies (210

A time-series of sediment cores collected from the Gulf of Mexico (2010-2014) were used to assess the spatial and temporal impacts on the benthos, quantify the recovery of benthic foraminiferal (BF) community structure and shell chemistry (δ13C) following the Deepwater Horizon (DWH) event. A significant decline in BF density (80-93%) and diversity...

Following the blowout of the Macondo well, a pulse in sedimentation resulted in changes in sedimentary redox conditions. This is demonstrated by downcore and temporal changes in the concentration of redox sensitive metals: Mn, Re, and Cd. Sediment cores collected in the NE Gulf of Mexico (GoM) reveal increased sedimentation after the Deepwater Hori...

Benjamin P. Flower, a gifted paleoceanographer and marine geologist, supportive colleague, and dedicated educator at the University of South Florida (USF) College of Marine Science (CMS) passed away on 1 July 2012 from complications related to a rare genetic immune dysfunction, Common Variable Immunodeficiency. He was 49 years old. During his brief...

The last deglaciation in the Northern Hemisphere was interrupted by two major stadials, the so-called "Mystery Interval" (17.5–14.5 ka) and the Younger Dryas (12.9–11.7 ka). During these events, the North Atlantic region was marked by cold surface conditions, yet simultaneous glacier and snowline retreat. Rerouting of Laurentide Ice Sheet meltw...

We report initial results to determine if select trace metals are effective indicators for the magnitude and spatial extent of Deep Water Horizon (DWH) oil contamination in Gulf of Mexico marine sediments and beach sands. Since crude oil is known to have elevated concentrations of nickel and vanadium, contamination can be detected even after the de...

The interactions between low-latitude Atlantic climate and high-latitude ice sheet variability represent an important issue in past abrupt climate change. Specifically, Laurentide Ice Sheet (LIS) meltwater input seems to be decoupled at the millennial scale from Gulf of Mexico sea-surface temperature (SST), as well as Greenland air temperature, dur...

Northern Gulf of Mexico (GOM) sediments document abrupt millennial-scale climate events that may be linked to significant changes in thermohaline circulation (THC) and Laurentide Ice Sheet (LIS) melting during the last deglaciation. Previous records exhibit episodic melting throughout the deglacial sequence until the Younger Dryas cold interval whe...

A series of recent papers has called for multiple radiocarbon dates on planktic foraminifera to assess strati-graphic continuity in deep-sea sediment cores. This recommendation comes from observations of anomalous 14 C dates in planktic foraminifera from the same stratigraphic level. Potential reasons include bioturbation, downslope transport, seco...

During the last deglaciation, Greenland ice core and North Atlantic sediment records exhibit multiple abrupt climate events including the Younger Dryas cold episode (12.9–11.7 ka). However, evidence for the presence of the Younger Dryas in the Gulf of Mexico (GOM) and the relationship between GOM sea surface temperature (SST) and high-latitude clim...

Meltwater input from the Laurentide Ice Sheet (LIS) has often been invoked as a cause of proximal sea surface temperature (SST) and salinity change in the North Atlantic and of regional to global climate change via its influence on the Atlantic meridional overturning circulation (AMOC). Here we review the evidence for meltwater inflow to the Gulf o...

Paleoclimate reconstructions from Orca Basin in the Gulf of Mexico (GOM) indicate a large (3-6°C) glacial to interglacial sea surface temperature (SST) change with multiple high-frequency coolings superimposed. Abrupt climate events such as the Oldest Dryas and the Younger Dryas exhibit significant SST decreases that coincide with positive delta18O...

During the last deglaciation, Greenland ice core and North Atlantic sediment records exhibit multiple abrupt climate events including the Younger Dryas cold episode (12.9-11.7 ka). However, evidence for the presence of the Younger Dryas in the Gulf of Mexico (GOM) and the relationship between GOM sea surface temperature (SST) and high-latitude clim...

Global climate change is widely recognized as the most important environmental problem today that requires complex, global solutions with international cooperation. Teaching the science of climate change is relatively simple compared to the challenges of determining solutions to this problem. It is important for students to learn that solutions do...

The objective of this study is to reconstruct the climate history of Tampa Bay, Florida over the Holocene epoch using the benthic foraminifera Ammonia beccarii from five sediment cores. Here we present a reconstruction based on oxygen isotopic ratios and Mg/Ca data that provides critical information on the history of climate changes in southwest Fl...

During the Last Glacial Termination from 18,000-8,000 cal. yrs B.P., meltwater routing of the Laurentide Ice Sheet (LIS) may have been linked to abrupt climatic events, such as the Younger Dryas. Previous studies show episodic meltwater input from the LIS, via the Mississippi River to the Gulf of Mexico (GOM) several thousand years before the onset...

Routing of low-salinity meltwater from the Laurentide Ice Sheet (LIS) into the North Atlantic via eastern outlets (e.g., St. Lawrence and Hudson River systems) and northern outlets (e.g., Hudson Bay and Arctic Ocean) is thought to have reduced Atlantic meridional overturning circulation (AMOC) and thereby triggered rapid regional to global climate...

Copyrighted by American Geophysical Union. An interlaboratory study of Mg/Ca and Sr/Ca ratios in three commercially available carbonate reference materials (BAM RS3, CMSI 1767, and ECRM 752-1) was performed with the participation of 25 laboratories that determine foraminiferal Mg/Ca ratios worldwide. These reference materials containing Mg/Ca in th...

An 11.28 m core from Tampa Bay, Fl (MD02 2579) reveals lacustrine sediments during the deglacial warming. Nineteen AMS radiocarbon dates were used to establish the chronology. Mg/Ca, Sr/Ca and 18O were measured on two species of brackish water ostracodes, Candona annae and Limnocythere floridensis. Variations in Mg/Ca and Sr/Ca reflect changes in w...

During Late Pleistocene glacial terminations Laurentide Ice Sheet (LIS) meltwater enters the Gulf of Mexico (GOM). As of yet, it is unclear whether or not weak warm periods, such as marine isotope stages (MIS) 3, 5a and 5c, were associated with meltwater discharge events. It is equally unknown how the timing of these events, if they existed, relate...

Understanding relative sea level (RSL) rise during periods of rapid climatic change is critical for evaluating modern sea level rise given the vulnerability of Antarctic ice shelves to collapse [ Hodgson et al, 2006], the retreat of the world's glaciers [ Oerlemans, 2005], and mass balance trends of the Greenland ice sheet [ Rignot and Kanagaratnam...

A thorough understanding of the carbon cycle is fundamental to understanding the eventual fate of CO2. To achieve this, students must understand individual processes, such as photosynthesis and respiration, as well as an integrated knowledge of how these processes relate to each other. In this "jigsaw" exercise, each student is assigned one five fu...

Evidence is emerging that Laurentide Ice Sheet (LIS) melting was decoupled from Greenland air temperature during the last glacial cycle. In particular, ice margin records indicate full retreat of the LIS during Greenland Stadial 2a ca. 16.9-14.7 ka, which spans Heinrich Event 1 in the North Atlantic (Denton et al., 2005). This finding squares with...

Sea surface temperature (SST) and delta18Osw records from the Gulf of Mexico (GOM) during the last deglaciation will help distinguish different mechanisms for abrupt climate change. Orca Basin is an ideal location to study climate changes in the GOM and to record the timing of meltwater discharge events through the Mississippi River; the anoxic hyp...

An 11.28 m core collected in Tampa Bay, FL reveals lacustrine sediments during the deglacial warming. Mg/Ca, Sr/Ca and O-18 were measured on two species of brackish water ostracodes. Our interpretation is that variations in Sr/Ca reflect changes in water chemistry and Mg/Ca variations reflect changes in both water temperature and chemistry. Applyin...

Evidence is emerging that the tropical climate system played a major role in global climate change during the last deglaciation. However, existing studies show that deglacial warming was asynchronous across the tropical band, complicating the identification of causal mechanisms. The Orca Basin in the northern Gulf of Mexico is ideally located to re...

Evidence is emerging that the tropical climate system played a major role in past global climate change during the last glacial cycle. However, existing studies indicate asynchronous temperature variability in the western equatorial Atlantic, complicating the identification of causal mechanisms. Because the Gulf of Mexico (GOM) is linked to the equ...

As part of the Western Hemisphere Warm Pool (WHWP), the Gulf of Mexico (GOM) is an important part of the tropical heat engine and a major source of heat and moisture to the North American continent and the higher latitudes. Laminated Orca Basin on the Louisiana slope in the northern GOM provides a unique, high-resolution record of WHWP sea-surface...

As part of the Western Hemisphere Warm Pool (WHWP), the Gulf of Mexico is an important source of heat and moisture to the North American continent and the higher latitudes. Orca Basin on the Louisiana slope in the northern Gulf of Mexico is ideally located to record deglacial WHWP sea-surface temperature (SST) warming in relation to meltwater input...

A new sediment core from the Orca Basin, Gulf of Mexico, will be helpful in determining the role of low latitude ocean dynamics in rapid climate change. The 31.79-m core (MD02-2551; 26o56.78'N, 91o21.75'W), obtained in July 2002 aboard the R/V Marion Dufrense will provide, for the first time, an opportunity to study Gulf of Mexico sea-surface tempe...

Two sediment cores were collected in Tampa Bay, Florida with the French R/V Marion Dufresne. One core (MD02-2579), is 11.3 m long and recovered sediments that contain a record of late Quaternary sea-level, climate and, environmental history. Tampa Bay averages less than 4 m water depth except in a natural karst-like depression in the central part o...

The Gulf of Mexico (GOM) is part of the Western Hemisphere Warm Pool providing a source of heat and moisture to the North American continent and Northern high latitudes. Paleoclimatic records from the GOM can test the hypothesis that the tropical climate system is an important driver of past global climate change. In July 2002, core MD02-2551 was t...

Oxygen isotope data from the Pleistocene section of Ocean Drilling Program (ODP) Site 1130 in the Great Australian Bight (GBA) show that shelf sediment export along the cool-water carbonate margin is linked to changes in global ice volume. The GAB is a site of extensive cool-water carbonate deposition, but little is known about how these deposits r...

Reconstruction of past sea surface temperatures (SST) is essential for understanding processes that have controlled climate change throughout Earth's history. The amplitude of tropical SST estimates using different proxies varies substantially, limiting our ability to constrain the role of ocean heat transport in climate change. Mg/Ca ratios in pla...

Glacial–interglacial variation in the marine Sr/Ca ratio has important implications for coral Sr thermometry [J.W. Beck et al., Science 257 (1992) 644–647]. A possible variation of 1–3% was proposed based on ocean models [H.M. Stoll and D.P. Schrag, Geochim. Cosmochim. Acta 62 (1998) 1107–1118]. Subsequently, studies have used fossil foraminifera t...

We have determined the chlorophyll pigment composition by liquid chromatography (LC) and LC/MS/MS in a 1.45-m long freeze core, representing 157 years of annually varved sedimentation, from Saanich Inlet, B.C, Canada. We investigated the very early diagenetic processes of chlorophyll a alteration in these anoxic sediments and the possible implicati...

Foraminiferal magnesium shows increasing promise as a paleothermometer, but the accuracy and precision are limited by biases introduced by partial dissolution, salinity variations, Mg-rich gametogenic calcite, and contaminant phases. We improved cleaning methods and reduced errors introduced by partial dissolution by sampling from well-preserved co...

Foraminiferal magnesium shows increasing promise as a paleothermometer, but the accuracy and precision are limited by biases introduced by partial dissolution, salinity variations, Mg-rich gametogenic calcite, and contaminant phases. We improved cleaning methods and reduced errors introduced by partial dissolution by sampling from well-preserved co...

Copyright 1996 by the American Geophysical Union We have used the vanadium concentration in cleaned foraminiferal calcite as a tracer of seawater V changes in the past. Since the benthic flux of vanadium is sensitive to the redox potential of sediments, changes in the vanadium concentration of seawater should be a reflection of changes that control...

We assess the potential of using foraminiferal calcite as a paleoceanographic indicator of seawater V concentrations. Laboratory culture experiments show that living benthic and planktonic foraminifera incorporate V into their test in direct proportion to seawater concentrations. Distribution coefficients relative to the culture solution are D = 2....

We developed a method to measure picogram quantities of vanadium in calcite and seawater by isotope dilution (ID) inductively coupled plasma mass spectrometry using electrothermal vaporization (ETV) to introduce the sample into the plasma. A 50V isotope spike enriched to 44 atom % was equilibrated with samples, followed by chemical purification by...

Precise and closely spaced alkalinity and total inorganic carbon measurements from the water column of the Cariaco Trench indicate an intense zone of sulfate reduction within the oxic waters above the O,-H,S interface. The chemical data suggest that sulfate reduction occurs in the presence of low oxygen levels. The resulting sulfide is subsequently...

The catalytic properties of spores of a marine Bacillus known to oxidize divalent manganese were used to perform laboratory Mn(II) oxidation experiments at environmental conditions of pH and Mn(II) concentration. We found that at pH 7.8 the initial kinetics of Mn(II) oxidation facilitated by the spores was four orders of magnitude greater than that...

Thesis (Ph. D.)--University of Washington, 1994. Vita. Includes bibliographical references (leaves [140]-157).