scholarly journals Elevated Post K-Pg Export Productivity in the Gulf of Mexico and Caribbean

2021 ◽  
Author(s):  
Christopher Lowery ◽  
Timothy Bralower
Keyword(s):  
Gulf Of Mexico ◽  
Regional Scale ◽  
Temporary Increase ◽  
Productivity Change ◽  
Published Data ◽  
Western Boundary ◽  
Geographic Scale ◽  
Export Production ◽  
Global Comparison ◽  
Export Productivity

The global heterogeneity in export productivity after the Cretaceous-Paleogene (K-Pg) mass extinction is well documented, with some sites showing no change on geologic timescales, some demonstrating sustained decline, and a few showing a somewhat surprising increase. However, these records come from sites so widespread that a key outstanding question is the geographic scale of changes in export productivity, and whether similar environments (open ocean gyres, western boundary currents) responded similarly or whether heterogeneity is unrelated to environment. To address this, we developed three new Ba/Ti export productivity records from sites in the Gulf of Mexico and Caribbean which, combined with published data from a fourth site in the Chicxulub Crater itself, allows us to reconstruct regional changes in post K-Pg export productivity for the first time. We find that, on a regional scale, export productivity change is homogenous, with all four sites showing a ~300 kyr period of elevated export production just after the boundary, followed by a longer period of decline. Interestingly, this interval of elevated export production appears to coincide with the post K-Pg global micrite layer, which is thought to at least partially have been produced by blooms of carbonate-producing cyanobacteria and other picophytoplankton. We note from a global comparison of sites that elevated export productivity appears to be most common in tropical waters, which suggests that changing plankton ecology evidenced by the micrite layer altered the biological pump in a way that encouraged a temporary increase in export production in the tropics.

scholarly journals Comparison of in situ and columnar aerosol spectral measurements during TexAQS-GoMACCS 2006: testing parameterizations for estimating aerosol fine mode properties

2009 ◽  
Vol 9 (4) ◽  
pp. 17465-17494
Author(s):  
D. B. Atkinson ◽  
P. Massoli ◽  
N. T. O'Neill ◽  
P. K. Quinn ◽  
S. Brooks ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Atmospheric Aerosols ◽  
Regional Scale ◽  
Atmospheric Composition ◽  
Light Extinction ◽  
Large Area ◽  
Light Extinction Coefficient ◽  
Spectral Models ◽  
Fine Mode

Abstract. During the 2006 Texas Air Quality Study and Gulf of Mexico Atmospheric Composition and Climate Study (TexAQS-GoMACCS 2006), the optical, chemical and microphysical properties of atmospheric aerosols were measured on multiple mobile platforms and at ground based stations. In situ measurements of the aerosol light extinction coefficient (σep) were performed by two multi-wavelength cavity ring-down (CRD) instruments, one located on board the NOAA R/V Ronald H. Brown (RHB) and the other located at the University of Houston, Moody Tower (UHMT). An AERONET sunphotometer was also located at the UHMT to measure the columnar aerosol optical depth (AOD). The σep data were used to extract the extinction Ångström exponent (åep), a measure of the wavelength dependence of σep. There was general agreement between the åep (and to a lesser degree σep measurements by the two spatially separated CRD instruments during multi-day periods, suggesting a regional scale consistency of the sampled aerosols. Two spectral models are applied to the σep and AOD data to extract the fine mode fraction of extinction (η) and the fine mode effective radius (Reff f). These two parameters are robust measures of the fine mode contribution to total extinction and the fine mode size distribution respectively. The results of the analysis are compared to Reff f values extracted using AERONET V2 retrievals and calculated from in situ particle size measurements on the RHB and at UHMT. During a time period when fine mode aerosols dominated the extinction over a large area extending from Houston/Galveston Bay and out into the Gulf of Mexico, the various methods for obtaining Reff f agree qualitatively (showing the same temporal trend) and quantitatively (pooled standard deviation=28 nm).

scholarly journals A global comparison of grassland biomass responses to CO 2 and nitrogen enrichment

2010 ◽  
Vol 365 (1549) ◽  
pp. 2047-2056 ◽  
Author(s):  
Mark Lee ◽  
Pete Manning ◽  
Janna Rist ◽  
Sally A. Power ◽  
Charles Marsh
Keyword(s):  
Large Scale ◽  
Meta Analysis ◽  
C Sequestration ◽  
Global Scale ◽  
Scale Model ◽  
Published Data ◽  
Climate Data ◽  
Forage Production ◽  
Global Comparison ◽  
N Enrichment

Grassland ecosystems cover vast areas of the Earth's surface and provide many ecosystem services including carbon (C) storage, biodiversity preservation and the production of livestock forage. Predicting the future delivery of these services is difficult, because widespread changes in atmospheric CO 2 concentration, climate and nitrogen (N) inputs are expected. We compiled published data from global change driver manipulation experiments and combined these with climate data to assess grassland biomass responses to CO 2 and N enrichment across a range of climates. CO 2 and N enrichment generally increased aboveground biomass (AGB) but effects of CO 2 enrichment were weaker than those of N. The response to N was also dependent on the amount of N added and rainfall, with a greater response in high precipitation regions. No relationship between response to CO 2 and climate was detected within our dataset, thus suggesting that other site characteristics, e.g. soils and plant community composition, are more important regulators of grassland responses to CO 2 . A statistical model of AGB response to N was used in conjunction with projected N deposition data to estimate changes to future biomass stocks. This highlighted several potential hotspots (e.g. in some regions of China and India) of grassland AGB gain. Possible benefits for C sequestration and forage production in these regions may be offset by declines in plant biodiversity caused by these biomass gains, thus necessitating careful management if ecosystem service delivery is to be maximized. An approach such as ours, in which meta-analysis is combined with global scale model outputs to make large-scale predictions, may complement the results of dynamic global vegetation models, thus allowing us to form better predictions of biosphere responses to environmental change.

Empirical relationships between temperature and nitrogen availability across North American forests

1992 ◽  
Vol 22 (5) ◽  
pp. 707-712 ◽  
Author(s):  
Xiwei Yin
Keyword(s):  
N Mineralization ◽  
Regional Scale ◽  
Mineral Soil ◽  
Published Data ◽  
N Availability ◽  
Net N Mineralization ◽  
Soil N ◽  
Litter Fall ◽  
Available N ◽  
N Pool

Published data were analyzed to examine whether nitrogen (N) availability varies along macroclimatic gradients in North America. Extractable N produced during 8-week aerobic laboratory incubation was used as an index of potential net N mineralization. Mean extractable N during the growing season in the forest floor plus top mineral soil was used as an index of the available N pool. Using multiple regression, potential net N mineralization was shown to increase with available N and with litter-fall N (R2 = 0.722). Available N increased with increasing total soil N and with decreasing mean January and July air temperatures (R2 = 0.770). These relationships appeared to hold also for deciduous and coniferous forests separately across regions. Results suggest that net N mineralization output under uniform temperature and moisture conditions can be generally expressed by variations of N input (litter fall) and the available soil N pool, and that the available soil N pool is predictable along a temperature gradient at a regional scale.

scholarly journals Environmental factors and occurrence of horseshoe crabs in the northcentral Gulf of Mexico

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0243478
Author(s):  
Maurice G. Estes ◽  
Ruth H. Carmichael ◽  
Xiongwen Chen ◽  
Sean C. Carter
Keyword(s):  
Environmental Factors ◽  
Gulf Of Mexico ◽  
Horseshoe Crab ◽  
Regional Scale ◽  
Environmental Drivers ◽  
Small Scale ◽  
Limiting Factor ◽  
Mobile Bay ◽  
Live Animal ◽  
Horseshoe Crabs

This study provides regional-scale data on drivers of horseshoe crab (Limulus polyphemus) presence along the northcentral Gulf of Mexico coast and has implications for understanding habitat suitability for sparse horseshoe crab populations of conservation concern worldwide. To collect baseline data on the relationship between environmental factors and presence of horseshoe crabs, we surveyed four sites from the Fort Morgan peninsula of Mobile Bay, Alabama (AL) to Horn Island, Mississippi (MS). We documented number, size and sex of live animals, molts, and carcasses as metrics of horseshoe crab presence and demographics for two years. Data were compared to in situ and remotely sensed environmental attributes to assess environmental drivers of occurrence during the time of study. Overall, greater evidence of horseshoe crab presence was found at western sites (Petit Bois and Horn Islands) compared to eastern sites (Dauphin Island, Fort Morgan peninsula), mediated by a combination of distance from areas of high freshwater discharge and interannual variation in weather. Higher sex ratios also were found associated with higher occurrence, west of Mobile Bay. Land cover, particularly Bare Land and Estuarine Emergent Wetland classes that are common to western sites, was most predictive of live animal and to some extent carcass occurrence. Our findings suggest that small-scale variation in habitat quality can affect occurrence of horseshoe crabs in sparse populations where density is not a limiting factor. Data from molts and carcasses were informative to supplement live animal data and may be useful to enhance ecological assessment and support conservation and management in regions with sparse populations.

scholarly journals KRILLBASE: a circumpolar database of Antarctic krill and salp numerical densities, 1926–2016

2017 ◽  
Vol 9 (1) ◽  
pp. 193-210 ◽  
Author(s):  
Angus Atkinson ◽  
Simeon L. Hill ◽  
Evgeny A. Pakhomov ◽  
Volker Siegel ◽  
Ricardo Anadon ◽  
...  
Keyword(s):  
Spatial Data ◽  
Antarctic Krill ◽  
Regional Scale ◽  
Published Data ◽  
Numerical Density ◽  
Data Set ◽  
Data Resource ◽  
Abundance Data ◽  
Krill Abundance ◽  
Contact Points

Abstract. Antarctic krill (Euphausia superba) and salps are major macroplankton contributors to Southern Ocean food webs and krill are also fished commercially. Managing this fishery sustainably, against a backdrop of rapid regional climate change, requires information on distribution and time trends. Many data on the abundance of both taxa have been obtained from net sampling surveys since 1926, but much of this is stored in national archives, sometimes only in notebooks. In order to make these important data accessible we have collated available abundance data (numerical density, no. m−2) of postlarval E. superba and salp individual (multiple species, and whether singly or in chains). These were combined into a central database, KRILLBASE, together with environmental information, standardisation and metadata. The aim is to provide a temporal-spatial data resource to support a variety of research such as biogeochemistry, autecology, higher predator foraging and food web modelling in addition to fisheries management and conservation. Previous versions of KRILLBASE have led to a series of papers since 2004 which illustrate some of the potential uses of this database. With increasing numbers of requests for these data we here provide an updated version of KRILLBASE that contains data from 15 194 net hauls, including 12 758 with krill abundance data and 9726 with salp abundance data. These data were collected by 10 nations and span 56 seasons in two epochs (1926–1939 and 1976–2016). Here, we illustrate the seasonal, inter-annual, regional and depth coverage of sampling, and provide both circumpolar- and regional-scale distribution maps. Krill abundance data have been standardised to accommodate variation in sampling methods, and we have presented these as well as the raw data. Information is provided on how to screen, interpret and use KRILLBASE to reduce artefacts in interpretation, with contact points for the main data providers. The DOI for the published data set is doi:10.5285/8b00a915-94e3-4a04-a903-dd4956346439.

scholarly journals Description and analysis of the debris flows occurred during 2008 in the Eastern Pyrenees

2010 ◽  
Vol 10 (7) ◽  
pp. 1635-1645 ◽  
Author(s):  
M. Portilla ◽  
G. Chevalier ◽  
M. Hürlimann
Keyword(s):  
Debris Flows ◽  
Regional Scale ◽  
Slope Angle ◽  
Large Mass ◽  
Rainfall Data ◽  
Published Data ◽  
Mountainous Regions ◽  
Initiation Zone ◽  
Eastern Pyrenees ◽  
Fluid Rheology

Abstract. Rainfall-triggered landslides taking place in the Spanish Eastern Pyrenees have usually been analysed on a regional scale. Most research focussed either on terrain susceptibility or on the characteristics of the critical rainfall, neglecting a detailed analysis of individual events. In contrast to other mountainous regions, research on debris flow has only been performed marginally and associated hazard has mostly been neglected. In this study, five debris flows, which occurred in 2008, are selected; and site specific descriptions and analysis regarding geology, morphology, rainfall data and runout were performed. The results are compared with worldwide data and some conclusions on hazard assessment are presented. The five events can be divided into two in-channel debris flows and three landslide-triggered debris flows. The in-channel generated debris flows exceeded 10 000 m3, which are unusually large mass movements compared to historic events which occurred in the Eastern Pyrenees. In contrast, the other events mobilised total volumes less than 2000 m3. The geomorphologic analysis showed that the studied events emphasize similar patterns when compared to published data focussing on slope angle in the initiation zone or catchment area. Rainfall data revealed that all debris flows were triggered by high intensity-short duration rainstorms during the summer season. Unfortunately, existing rainfall thresholds in the Eastern Pyrenees consider long-lasting rainfall, usually occurring in autumn/winter. Therefore, new thresholds should be established taking into account the rainfall peak intensity in mm/h, which seems to be a much more relevant factor for summer than the event's total precipitation. The runout analysis of the 2008 debris flows confirms the trend that larger volumes generally induce higher mobility. The numerical simulation of the Riu Runer event shows that its dynamic behaviour is well represented by Voellmy fluid rheology. A maximum front velocity of 7 m/s was back-analysed for the transit section and even on the fan velocities larger than 2 m/s were obtained. This preliminary analysis of the major Eastern Pyrenean debris flows represents the first background for future studies. Additional research on other events is necessary to support the results presented herein, and to properly assess and reduce hazard related to debris flows.

scholarly journals A Multidisciplinary Approach to Investigate Deep-Pelagic Ecosystem Dynamics in the Gulf of Mexico Following Deepwater Horizon

2020 ◽  
Vol 7 ◽  
Author(s):  
April B. Cook ◽  
Andrea M. Bernard ◽  
Kevin M. Boswell ◽  
Heather Bracken-Grissom ◽  
Marta D’Elia ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Water Column ◽  
Large Scale ◽  
Biological Diversity ◽  
Community Integration ◽  
Deepwater Horizon ◽  
Ecosystem Dynamics ◽  
Western Boundary ◽  
Genetic Sequencing ◽  
Oceanic Ecosystem

The pelagic Gulf of Mexico (GoM) is a complex system of dynamic physical oceanography (western boundary current, mesoscale eddies), high biological diversity, and community integration via diel vertical migration and lateral advection. Humans also heavily utilize this system, including its deep-sea components, for resource extraction, shipping, tourism, and other commercial activity. This utilization has had impacts, some with disastrous consequences. The Deepwater Horizon oil spill (DWHOS) occurred at a depth of ∼1500 m (Macondo wellhead), creating a persistent and toxic mixture of hydrocarbons and dispersant in the deep-pelagic (water column below 200 m depth) habitat. In order to assess the impacts of the DWHOS on this habitat, two large-scale research programs, described herein, were designed and executed. These programs, ONSAP and DEEPEND, aimed to quantitatively characterize the oceanic ecosystem of the northern GoM and to establish a time-series with which natural and anthropogenic changes could be detected. The approach was multi-disciplinary in nature and included in situ sampling, acoustic sensing, water column profiling and sampling, satellite remote sensing, AUV sensing, numerical modeling, genetic sequencing, and biogeochemical analyses. The synergy of these methodologies has provided new and unprecedented perspectives of an oceanic ecosystem with respect to composition, connectivity, drivers, and variability.

scholarly journals Climatological moisture sources for the Western North American Monsoon through a Lagrangian approach: their influence on precipitation intensity

2019 ◽  
Vol 10 (1) ◽  
pp. 59-72 ◽  
Author(s):  
Paulina Ordoñez ◽  
Raquel Nieto ◽  
Luis Gimeno ◽  
Pedro Ribera ◽  
David Gallego ◽  
...  
Keyword(s):  
Water Vapor ◽  
Gulf Of Mexico ◽  
North American ◽  
Regional Scale ◽  
Caribbean Sea ◽  
Lagrangian Approach ◽  
Specific Humidity ◽  
North American Monsoon ◽  
The Caribbean ◽  
Upper Level

Abstract. This work examines the origin of atmospheric water vapor arriving to the western North American monsoon (WNAM) region over a 34-year period (1981–2014) using a Lagrangian approach. This methodology computes budgets of evaporation minus precipitation (E−P) by calculating changes in the specific humidity of thousands of air particles advected into the study area by the observed winds. The length of the period analyzed (34 years) allows the method to identify oceanic and terrestrial sources of moisture to the WNAM region from a climatological perspective. During the wet season, the WNAM region itself is on average the main evaporative source, followed by the Gulf of California. However, water vapor originating from the Caribbean Sea, the Gulf of Mexico, and terrestrial eastern Mexico is found to influence regional-scale rainfall generation. Enhanced (reduced) moisture transport from the Caribbean Sea and the Gulf of Mexico from 4 to 6 days before precipitation events seems to be responsible for increased (decreased) rainfall intensity on regional scales during the monsoon peak. Westward propagating mid- to upper-level inverted troughs (IVs) seem to favor these water vapor fluxes from the east. In particular, a 200 % increase in the moisture flux from the Caribbean Sea to the WNAM region is found to be followed by the occurrence of heavy precipitation in the WNAM area a few days later. Low-level troughs off the coast of northwestern Mexico and upper-level IVs over the Gulf of Mexico are also related to these extreme rainfall events.

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