Neogene Benthic Foraminiferal Biofacies, Paleobathymetry, and Paleoenvironments of a Gulf of Mexico Transect

2018 ◽  
Vol 48 (4) ◽  
pp. 356-372
Author(s):  
Miriam E. Katz ◽  
Kenneth G. Miller ◽  
Michael A. Kaminski ◽  
James V. Browning
Keyword(s):  
Gulf Of Mexico ◽  
Middle Miocene ◽  
Low Oxygen ◽  
High Productivity ◽  
Upper Miocene ◽  
Fault Tectonics ◽  
Lower Oxygen ◽  
Oxygen Conditions ◽  
Minimum Zone ◽  
Oxygen Minimum

Abstract We document Neogene benthic foraminiferal biofacies changes on a depth transect of six Gulf of Mexico industry wells (sidewall and cutting samples) that is oblique to the coast and extends from Main Pass to Green Canyon (offshore Alabama to Louisiana, USA). Calcareous nannofossil and planktonic foraminiferal biostratigraphic control provides the framework to make interwell comparisons of the benthic foraminiferal biofacies; these comparisons provide the basis for paleobathymetric and paleoenvironmental interpretations and to identify useful benthic foraminiferal biostratigraphic markers in this region. Benthic foraminiferal faunas indicate that Neogene paleodepths were slightly shallower at the eastern wells and deepened towards the western wells. Calcareous benthic foraminiferal biofacies dominated by Uvigerina spp. indicate that paleoenvironments characterized by low-oxygen conditions and/or high productivity occurred periodically during deposition along the transect. This is supported by repeated occurrences of a distinctive assemblage of agglutinated foraminifera (known as the “Agua Salada Fauna”) that is typical of dysaerobic environments. Evidence of intensified low-oxygen/high-productivity environments are recorded in lowermost Middle Miocene sediments at some locations and are present at all wells in Upper Miocene deposits. In Upper Miocene-Pliocene sediments, oxygen levels appear to have been related to paleodepth, indicating that the development of lower oxygen conditions was the result of an expansion or migration of the oxygen minimum zone. Our results are consistent with a global cause for the expansion of the oxygen minumum zone during the Late Miocene and widespread increase in export production. Our study shows that despite problems in well cuttings (cavings, inconsistent sampling) and complications in regional salt and fault tectonics, well transects can provide coherent benthic foraminiferal biofacies patterns that reveal paleobathymetric and paleoenvironmental changes in the Gulf of Mexico.

scholarly journals Benthic phosphorus cycling in the Peruvian oxygen minimum zone

2016 ◽  
Vol 13 (5) ◽  
pp. 1367-1386 ◽  
Author(s):  
Ulrike Lomnitz ◽  
Stefan Sommer ◽  
Andrew W. Dale ◽  
Carolin R. Löscher ◽  
Anna Noffke ◽  
...  
Keyword(s):  
Water Column ◽  
Surface Sediments ◽  
Solid Phase ◽  
Continental Margins ◽  
Low Oxygen ◽  
Anoxic Waters ◽  
Oxygen Conditions ◽  
Bottom Waters ◽  
Minimum Zone ◽  
Oxygen Minimum

Abstract. Oxygen minimum zones (OMZs) that impinge on continental margins favor the release of phosphorus (P) from the sediments to the water column, enhancing primary productivity and the maintenance or expansion of low-oxygen waters. A comprehensive field program in the Peruvian OMZ was undertaken to identify the sources of benthic P at six stations, including the analysis of particles from the water column, surface sediments, and pore fluids, as well as in situ benthic flux measurements. A major fraction of solid-phase P was bound as particulate inorganic P (PIP) both in the water column and in sediments. Sedimentary PIP increased with depth in the sediment at the expense of particulate organic P (POP). The ratio of particulate organic carbon (POC) to POP exceeded the Redfield ratio both in the water column (202 ± 29) and in surface sediments (303 ± 77). However, the POC to total particulate P (TPP = POP + PIP) ratio was close to Redfield in the water column (103 ± 9) and in sediment samples (102 ± 15). This suggests that the relative burial efficiencies of POC and TPP are similar under low-oxygen conditions and that the sediments underlying the anoxic waters on the Peru margin are not depleted in P compared to Redfield. Benthic fluxes of dissolved P were extremely high (up to 1.04 ± 0.31 mmol m−2 d−1), however, showing that a lack of oxygen promotes the intensified release of dissolved P from sediments, whilst preserving the POC / TPP burial ratio. Benthic dissolved P fluxes were always higher than the TPP rain rate to the seabed, which is proposed to be caused by transient P release by bacterial mats that had stored P during previous periods when bottom waters were less reducing. At one station located at the lower rim of the OMZ, dissolved P was taken up by the sediments, indicating ongoing phosphorite formation. This is further supported by decreasing porewater phosphate concentrations with sediment depth, whereas solid-phase P concentrations were comparatively high.

scholarly journals Benthic phosphorus cycling in the Peruvian oxygen minimum zone

2015 ◽  
Vol 12 (20) ◽  
pp. 16755-16801 ◽  
Author(s):  
U. Lomnitz ◽  
S. Sommer ◽  
A. W. Dale ◽  
C. R. Löscher ◽  
A. Noffke ◽  
...  
Keyword(s):  
Water Column ◽  
Surface Sediments ◽  
Solid Phase ◽  
Continental Margins ◽  
Low Oxygen ◽  
Oxygen Minimum Zones ◽  
Oxygen Conditions ◽  
Bottom Waters ◽  
Minimum Zone ◽  
Oxygen Minimum

Abstract. Oxygen minimum zones (OMZs) that impinge on continental margins favor the release of phosphorus (P) from the sediments to the water column, enhancing primary productivity and the maintenance or expansion of low-oxygen waters. A comprehensive field program in the Peruvian OMZ was undertaken to identify the sources of benthic P, including the analysis of particles from the water column, surface sediments and pore fluids as well as in situ benthic flux measurements. A major fraction of solid phase P was bound as particulate inorganic P (PIP) both in the water column and in sediments. Sedimentary PIP increased with depth in the sediment at the expense of particulate organic P (POP). The ratio of particulate organic carbon (POC) to POP exceeded the Redfield Ratio both in the water column (202 ± 29) and in surface sediments (303 ± 77). However, the POC to total particulate P (TPP = POP + PIP) ratio was close to Redfield in the water column (103 ± 9) and in sediment samples (102 ± 15) taken from the core of the OMZ. This observation suggests that the burial efficiencies of POC and TPP are similar under the low oxygen conditions prevailing in the Peruvian OMZ. Benthic fluxes of dissolved P were extremely high (up to 1.04 ± 0.31 mmol m−2 d−1) and exceeded the fluxes resulting from the degradation of particulate organic matter raining to the seabed. Most of the excess P may have been released by bacterial mats that had stored P during previous periods when bottom waters were less reducing. At one station located at the lower rim of the OMZ, dissolved P was taken up by the sediments indicating recent phosphorite formation.

scholarly journals Sink or link? The bacterial role in benthic carbon cycling in the Arabian Sea's oxygen minimum zone

2013 ◽  
Vol 10 (11) ◽  
pp. 6879-6891 ◽  
Author(s):  
L. Pozzato ◽  
D. Van Oevelen ◽  
L. Moodley ◽  
K. Soetaert ◽  
J. J. Middelburg
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Particulate Organic Matter ◽  
Experimental Period ◽  
Oxygen Minimum Zone ◽  
Trophic Levels ◽  
Isotope Tracer ◽  
Oxygen Conditions ◽  
Minimum Zone ◽  
Oxygen Minimum

Abstract. The bacterial loop, the consumption of dissolved organic matter (DOM) by bacteria and subsequent transfer of bacterial carbon to higher trophic levels, plays a prominent role in pelagic food webs. However, its role in sedimentary ecosystems is not well documented. Here we present the results of isotope tracer experiments performed under in situ oxygen conditions in sediments from inside and outside the Arabian Sea's oxygen minimum zone (OMZ) to study the importance of the microbial loop in this setting. Particulate organic matter, added as phytodetritus, was processed by bacteria, protozoa and metazoans, while dissolved organic matter was processed only by bacteria and there was very little, if any, transfer to higher trophic levels within the 7 day experimental period. This lack of significant transfer of bacterial-derived carbon to metazoan consumers indicates that the bacterial loop is rather inefficient, in sediments both inside and outside the OMZ. Moreover, metazoans directly consumed labile particulate organic matter resources and thus competed with bacteria for phytodetritus.

Performance of an Ocean Buoyancy Glider in a Coastal Region: Application to the Gulf of Mexico Hypoxic Zone

2017 ◽  
Vol 51 (4) ◽  
pp. 41-51
Author(s):  
Elizabeth Ramey ◽  
Steven F. DiMarco ◽  
Karen Dreger ◽  
Heather M. Zimmerle
Keyword(s):  
Gulf Of Mexico ◽  
Action Plan ◽  
Coastal Region ◽  
Ocean Bottom ◽  
Low Oxygen ◽  
Northern Gulf Of Mexico ◽  
Hypoxic Zone ◽  
Horizontal Stratification ◽  
Oxygen Conditions ◽  
Oil Gas

AbstractThe Gulf of Mexico Coastal Hypoxia Glider Experiment was designed to assess the feasibility of using ocean glider technology in the coastal hypoxic zone of the northern Gulf of Mexico in Summer/Fall 2014. The objectives were (1) to coordinate and operate multiple autonomous buoyancy ocean gliders in depths less than 50 m and (2) to determine how close to the bottom gliders can reliably reach without making contact. Strong vertical and horizontal stratification gradients, strong coastal currents, and the low-oxygen conditions that occur within the lower water column characterize the coastal area of the northern Gulf of Mexico. These environmental conditions combine with the presence of more than 5,000 surface piercing oil/gas structures to make piloting and navigation in the region challenging. We quantify glider performance to assess the usefulness of buoyancy gliders to address the National Oceanic and Atmospheric Administration Action Plan goal to monitor the spatial extent, duration, and severity of the Gulf hypoxic zone. We find that the gliders, despite the operational challenges, were consistently able to travel from the surface to the oxygen-depleted depths of subpycnocline waters, that is, within 2 m of the ocean bottom. Our assessment is that gliders are able to provide real-time observations suitable to monitor coastal hypoxia.

scholarly journals Middle Miocene oxygen minimum zone expansion offshore West Africa: Evidence for global cooling precursor events

Geology ◽  
2009 ◽  
Vol 37 (8) ◽  
pp. 699-702 ◽  
Author(s):  
S. Kender ◽  
V.L. Peck ◽  
R.W. Jones ◽  
M.A. Kaminski
Keyword(s):  
West Africa ◽  
Middle Miocene ◽  
Oxygen Minimum Zone ◽  
Global Cooling ◽  
Minimum Zone ◽  
Oxygen Minimum

scholarly journals Ammonium excretion and oxygen respiration of tropical copepods and euphausiids exposed to oxygen minimum zone conditions

2016 ◽  
Vol 13 (8) ◽  
pp. 2241-2255 ◽  
Author(s):  
Rainer Kiko ◽  
Helena Hauss ◽  
Friedrich Buchholz ◽  
Frank Melzner
Keyword(s):  
Carbon Dioxide ◽  
Partial Pressure ◽  
Respiratory Activity ◽  
Ammonium Excretion ◽  
Calanoid Copepods ◽  
Low Oxygen ◽  
Oxygen Levels ◽  
Minimum Zone ◽  
Excretion Rates ◽  
Oxygen Minimum

Abstract. Calanoid copepods and euphausiids are key components of marine zooplankton communities worldwide. Most euphausiids and several copepod species perform diel vertical migrations (DVMs) that contribute to the export of particulate and dissolved matter to midwater depths. In vast areas of the global ocean, and in particular in the eastern tropical Atlantic and Pacific, the daytime distribution depth of many migrating organisms corresponds to the core of the oxygen minimum zone (OMZ). At depth, the animals experience reduced temperature and oxygen partial pressure (pO2) and an increased carbon dioxide partial pressure (pCO2) compared to their near-surface nighttime habitat. Although it is well known that low oxygen levels can inhibit respiratory activity, the respiration response of tropical copepods and euphausiids to relevant pCO2, pO2, and temperature conditions remains poorly parameterized. Further, the regulation of ammonium excretion at OMZ conditions is generally not well understood. It was recently estimated that DVM-mediated ammonium supply could fuel bacterial anaerobic ammonium oxidation – a major loss process for fixed nitrogen in the ocean considerably. These estimates were based on the implicit assumption that hypoxia or anoxia in combination with hypercapnia (elevated pCO2) does not result in a down-regulation of ammonium excretion. We exposed calanoid copepods from the Eastern Tropical North Atlantic (ETNA; Undinula vulgaris and Pleuromamma abdominalis) and euphausiids from the Eastern Tropical South Pacific (ETSP; Euphausia mucronata) and the ETNA (Euphausia gibboides) to different temperatures, carbon dioxide and oxygen levels to study their survival, respiration and excretion rates at these conditions. An increase in temperature by 10 °C led to an approximately 2-fold increase of the respiration and excretion rates of U. vulgaris (Q10, respiration = 1.4; Q10, NH4-excretion = 1.6), P. abdominalis (Q10, respiration = 2.0; Q10, NH4-excretion = 2.4) and E. gibboides (Q10, respiration = 2.0; Q10, NH4-excretion = 2.4; E. mucronata not tested). Exposure to differing carbon dioxide levels had no overall significant impact on the respiration or excretion rates. Species from the ETNA were less tolerant to low oxygen levels than E. mucronata from the ETSP, which survived exposure to anoxia at 13 °C. Respiration and excretion rates were reduced upon exposure to low oxygen levels, albeit at different species-specific levels. Reduction of the excretion and respiration rates in ETNA species occurred at a pO2 of 0.6 (P. abdominalis) and 2.4 kPa (U. vulgaris and E. gibboides) at OMZ temperatures. Such low oxygen levels are normally not encountered by these species in the ETNA. E. mucronata however regularly migrates into the strongly hypoxic to anoxic core of the ETSP OMZ. Exposure to low oxygen levels led to a strong reduction of respiration and ammonium excretion in E. mucronata (pcrit  respiration = 0.6, pcrit NH4-excretion = 0.73). A drastic reduction of respiratory activity was also observed by other authors for euphausiids, squat lobsters and calanoid copepods, but was not yet accounted for when calculating DVM-mediated active fluxes into the ETSP OMZ. Current estimates of DVM-mediated active export of carbon and nitrogen into the ETSP OMZ are therefore likely too high and future efforts to calculate these export rates should take the physiological responses of migratory species to OMZ conditions into account.

Biogeochemical Controls on Coastal Hypoxia

2019 ◽  
Vol 11 (1) ◽  
pp. 105-130 ◽  
Author(s):  
Katja Fennel ◽  
Jeremy M. Testa
Keyword(s):  
Oxygen Depletion ◽  
Nutrient Loads ◽  
Low Oxygen ◽  
Basic Principles ◽  
Oxygen Minimum Zones ◽  
Coastal Systems ◽  
Oxygen Conditions ◽  
Anoxic Zones ◽  
Cross System ◽  
Oxygen Minimum

Aquatic environments experiencing low-oxygen conditions have been described as hypoxic, suboxic, or anoxic zones; oxygen minimum zones; and, in the popular media, the misnomer “dead zones.” This review aims to elucidate important aspects underlying oxygen depletion in diverse coastal systems and provides a synthesis of general relationships between hypoxia and its controlling factors. After presenting a generic overview of the first-order processes, we review system-specific characteristics for selected estuaries where adjacent human settlements contribute to high nutrient loads, river-dominated shelves that receive large inputs of fresh water and anthropogenic nutrients, and upwelling regions where a supply of nutrient-rich, low-oxygen waters generates oxygen minimum zones without direct anthropogenic influence. We propose a nondimensional number that relates the hypoxia timescale and water residence time to guide the cross-system comparison. Our analysis reveals the basic principles underlying hypoxia generation in coastal systems and provides a framework for discussing future changes.

scholarly journals Differential Distribution and Determinants of Ammonia Oxidizing Archaea Sublineages in the Oxygen Minimum Zone off Costa Rica

2019 ◽  
Vol 7 (10) ◽  
pp. 453 ◽  
Author(s):  
Yanhong Lu ◽  
Xiaomin Xia ◽  
Shunyan Cheung ◽  
Hongmei Jing ◽  
Hongbin Liu
Keyword(s):  
Costa Rica ◽  
Water Column ◽  
Gulf Of California ◽  
North Pacific Ocean ◽  
Oxygen Minimum Zone ◽  
Low Oxygen ◽  
Environmental Determinants ◽  
Ammonia Oxidizing Archaea ◽  
Minimum Zone ◽  
Oxygen Minimum

Ammonia oxidizing archaea (AOA) are microbes that are widely distributed in the ocean that convert ammonia to nitrite for energy acquisition in the presence of oxygen. Recent study has unraveled highly diverse sublineages within the previously defined AOA ecotypes (i.e., water column A (WCA) and water column B (WCB)), although the eco-physiology and environmental determinants of WCB subclades remain largely unclear. In this study, we examined the AOA communities along the water columns (40–3000 m depth) in the Costa Rica Dome (CRD) upwelling region in the eastern tropical North Pacific Ocean. Highly diverse AOA communities that were significantly different from those in oxygenated water layers were observed in the core layer of the oxygen minimum zone (OMZ), where the dissolved oxygen (DO) concentration was < 2μM. Moreover, a number of AOA phylotypes were found to be enriched in the OMZ core. Most of them were negatively correlated with DO and were also detected in other OMZs in the Arabian Sea and Gulf of California, which suggests low oxygen adaptation. This study provided the first insight into the differential niche partitioning and environmental determinants of various subclades within the ecotype WCB. Our results indicated that the ecotype WCB did indeed consist of various sublineages with different eco-physiologies, which should be further explored.

A new species of the family Thyasiridae (Mollusca: Bivalvia) from the oxygen minimum zone of the Pakistan margin

2006 ◽  
Vol 86 (2) ◽  
pp. 411-416 ◽  
Author(s):  
P. Graham Oliver ◽  
Lisa Levin
Keyword(s):  
New Species ◽  
Water Depth ◽  
Oxygen Minimum Zone ◽  
Low Oxygen ◽  
Oxygen Environment ◽  
The Family ◽  
Minimum Zone ◽  
Generic Affinity ◽  
A New Species ◽  
Oxygen Minimum

A new species of Thyasiridae, ‘Leptaxinus’ indusarium sp. nov. is described from the Indus margin, off Pakistan. The generic affinity is tentative and possible alternatives are discussed. It occurs between 800 m and 1000 m water depth in a low oxygen environment, where it is relatively abundant. The ecological setting is described and data suggest that this species is not chemosymbiotic.

Sign in / Sign up

Export Citation Format

Share Document