Earth Sciences Commons^™

Climate And Plant Controls On Soil Organic Matter In Coastal Wetlands, Michael J. Osland, Christopher A. Gabler, James B. Grace, Richard H. Day, Meagan L. Mccoy, Jennie L. Mcleod, Andrew S. From, Nicholas M. Enwright, Laura C. Feher, Camille L. Stagg

School of Earth, Environmental, & Marine Sciences Faculty Publications

Coastal wetlands are among the most productive and carbon‐rich ecosystems on Earth. Long‐term carbon storage in coastal wetlands occurs primarily belowground as soil organic matter (SOM). In addition to serving as a carbon sink, SOM influences wetland ecosystem structure, function, and stability. To anticipate and mitigate the effects of climate change, there is a need to advance understanding of environmental controls on wetland SOM. Here, we investigated the influence of four soil formation factors: climate, biota, parent materials, and topography. Along the northern Gulf of Mexico, we collected wetland plant and soil data across elevation and zonation gradients within 10 …

Effect Of Surrounding Vegetation On Microbial Survival Or Die-Off On Watermelon Surface In An Agriculture Setting, Vijay Singh Chhetri, Kathryn Fontenot, Ronald Strahan, Veerachandra K. Yemmireddy, Katheryn J. Parraga Estrada, Achyut Adhikari

School of Earth, Environmental, & Marine Sciences Faculty Publications

Preharvest contamination of produce with food borne pathogens has been a major food safety issue. In this study, we investigated the effect of surrounding vegetation on the survival of natural and inoculated generic Escherichia coli on watermelon rinds in an agricultural field setting. There was no significant difference (p > .05) on the populations of natural generic E. coli (1–1.46 log Most Probable Number (MPN)/sample) and coliforms (E. coli inoculated on watermelon rind discs was variable with the level of vegetation. A significant reduction in generic E. coli count was observed within 12 hr at all vegetation levels. After 108 …

First Record Of Black Corals (Antipatharia) In Shallow Coastal Waters Of Northern Chile By Means Of Underwater Video, Matthias Gorny, Erin E. Easton, Javier Sellanes

School of Earth, Environmental, & Marine Sciences Faculty Publications

This record is the first report of black corals (Antipatharia) in shallow waters of the continental coast of Chile, and extends their geographical range in shallow waters of the upper continental shelf of South America by ~3000 km from Ecuador (~1°S) to Coquimbo, Chile (~29°S). Specimens were observed between 70 and 107 m on three underwater video transects executed in July 2016 on the rocky reef El Toro, which is located about 65 km northwest of Coquimbo. The images were taken with the cameras of a remotely operated vehicle (ROV) at a distance of about two meters from the rocks. …

Source-Specific Pollution Exposure And Associations With Pulmonary Response In The Atlanta Commuters Exposure Studies, Jenna R. Krall, Chandresh N. Ladva, Armistead G. Russell, Rachel Golan, Xing Peng, Guoliang Shi, Roby Greenwald, Amit U. Raysoni, Lance A. Waller, Jeremy A. Sarnat

School of Earth, Environmental, & Marine Sciences Faculty Publications

Concentrations of traffic-related air pollutants are frequently higher within commuting vehicles than in ambient air. Pollutants found within vehicles may include those generated by tailpipe exhaust, brake wear, and road dust sources, as well as pollutants from in-cabin sources. Sourcespecific pollution, compared to total pollution, may represent regulation targets that can better protect human health. We estimated source-specific pollution exposures and corresponding pulmonary response in a panel study of commuters. We used constrained positive matrix factorization to estimate source-specific pollution factors and, subsequently, mixed effects models to estimate associations between source-specific pollution and pulmonary response. We identified four pollution factors …

Extraction Of Metazoan Meiofauna From Muddy Deep-Sea Samples: Operator And Taxon Effects On Efficiency, Melissa Rohal, David Thistle, Erin E. Easton

School of Earth, Environmental, & Marine Sciences Faculty Publications

Deep-sea metazoan meiofaunal specimens are usually extracted from muddy samples by centrifugation in a fluid in which meiofauna tend to float and sediment particles tend to sink. Although the procedure is in common use, its efficiency has seldom been examined. The study reported here showed that well-trained operators extracted metazoan meiofauna with efficiencies that were different enough to be a concern in quantitative studies. Therefore, samples should be assigned to operators in a stratified-random manner. In the course of these studies, both operators also extracted individuals of the common nematode family Desmoscolecidae significantly less efficiently than other nematode families, a …

Interactive Effects Of Hypoxia And Pcb Co-Exposure On Expression Of Cyp1a And Its Potential Regulators In Atlantic Croaker Liver, Md. Saydur Rahman, Peter Thomas

School of Earth, Environmental, & Marine Sciences Faculty Publications

Although marine and coastal environments which are contaminated with xenobiotic organic compounds often become hypoxic during the summer, the interactive effects of hypoxia and xenobiotic exposure on marine species such as teleost fishes remain poorly understood. The expression and activity of monooxygenase enzyme cytochrome P450-1A (CYP1A) in fishes are upregulated by exposure to polychlorinated biphenyls (PCBs), whereas they are down-regulated during hypoxia exposure. We investigated the interactive effects of hypoxia and PCB co-exposure on hepatic CYP1A expression in Atlantic croaker and on potential regulators of CYP1A. Croaker were exposed to hypoxia (1.7 mg/L dissolved oxygen), 3,3′,4,4′-tetrachlorobiphenyl (PCB 77, dose: 2 …

Mesoscale Effects On Carbon Export: A Global Perspective, Cheryl S. Harrison, Matthew C. Long, Nicole S. Lovenduski, Jefferson K. Moore

School of Earth, Environmental, & Marine Sciences Faculty Publications

Carbon export from the surface to the deep ocean is a primary control on global carbon budgets and is mediated by plankton that are sensitive to physical forcing. Earth system models generally do not resolve ocean mesoscale circulation ((10–100) km), scales that strongly affect transport of nutrients and plankton. The role of mesoscale circulation in modulating export is evaluated by comparing global ocean simulations conducted at 1∘ and 0.1∘ horizontal resolution. Mesoscale resolution produces a small reduction in globally integrated export production (<2%); however, the impact on local export production can be large (±50%), with compensating effects in different ocean basins. With mesoscale resolution, improved representation of coastal jets block off-shelf transport, leading to lower export in regions where shelf-derived nutrients fuel production. Export is further reduced in these regions by resolution of mesoscale turbulence, which restricts the spatial area of production. Maximum mixed layer depths are narrower and deeper across the Subantarctic at higher resolution, driving locally stronger nutrient entrainment and enhanced summer export production. In energetic regions with seasonal blooms, such as the Subantarctic and North Pacific, internally generated mesoscale variability drives substantial interannual variation in local export production. These results suggest that biogeochemical tracer dynamics show different sensitivities to transport biases than temperature and salinity, which should be considered in the formulation and validation of physical parameterizations. Efforts to compare estimates of export production from observations and models should account for large variability in space and time expected for regions strongly affected by mesoscale circulation.

Effects Of Herbivores, Wave Exposure And Depth On Benthic Coral Communities Of The Easter Island Ecoregion, Erin E. Easton, Carlos F. Gaymer, Alan M. Friedlander, James J. Herlan

School of Earth, Environmental, & Marine Sciences Faculty Publications

The Easter Island ecoregion includes Rapa Nui (Easter Island; RN), with a human population of ~5600, and the uninhabited Salas y Gómez (SyG). Although the culture and terrestrial ecology of RN have been well studied, we know little about the marine environment of these islands, particularly the interplay among herbivores, algae, and corals, and how coral reef communities differ between islands, by wave energy exposure, and between depths. To address the potential roles of herbivores, wave-energy exposure, and depth on the sessile benthic communities, we examined herbivorous fish biomass, sea urchin (Diadema savignyi) density, and algal and coral …

Amphibians And Reptiles Of C. E. Miller Ranch And The Sierra Vieja, Chihuahuan Desert, Texas, Usa, Drew R. Davis, Travis J. Laduc

School of Earth, Environmental, & Marine Sciences Faculty Publications

We report the occurrence of 50 species of amphibians and reptiles recently collected on C. E. Miller Ranch and the Sierra Vieja in the Chihuahuan Desert of Texas, USA and describe their perceived distribution and abundance across various habitat associations of the region. Our recent surveys follow intense, historic sampling of amphibians and reptiles from this region in 1948. Of the 50 species detected in recent surveys, six were not collected in 1948 and an additional three species documented in 1948 have yet to be detected in a 14-year period of recent surveys. Combining data from both historic and recent …

Preliminary Multivariate Comparison Of Coral Assemblages On Carbonate Banks In The Western Gulf Of Mexico, Rebekah E. Rodriguez, Erin E. Easton, Thomas C. Shirley, John W. Tunnell, David Hicks

School of Earth, Environmental, & Marine Sciences Faculty Publications

Hermatypic corals flourished on reefs in the Gulf of Mexico (GOM) in the late Pleistocene and early Holocene. Today, many of these relict reefs are mesophotic banks that have unique coral assemblages and provide critical habitat; however, the South Texas Banks (STB) lack quantitative surveys. Therefore, we used a remotely operated vehicle to conduct quantitative surveys of 5 banks: Baker, Aransas, Dream, Blackfish Ridge, and Harte. Coral communities, based on estimated coral densities (colonies/m2), significantly differed among banks for terraces, slopes, and overall (combined terrace and slope) communities for most banks examined. Within banks, terrace and slope communities significantly differed …

First Record Of The Yellowfin Soldierfish, Myripristis Chryseresjordan & Evermann, 1903, In The Easter Island Ecoregion, Erin E. Easton, Javier Sellanes, Matthias Gorny

School of Earth, Environmental, & Marine Sciences Faculty Publications

Myripristis chryseres Jordan & Evermann, 1903, is recorded for the first time in the Easter Island Ecoregion. Two specimens were observed swimming along a rock cliff and entering a cavern at ∼163 m depth near the peak of Pukao seamount, located ∼85 km (46 nm) west of Easter Island. This report expands the geographic range of M. chryseres eastward by ∼3,800 km and is the first report of the species for the eastern Pacific. It is unclear whether this new record is indicative of a relatively recent range expansion or a lack of visual surveys in the region, which …

Ecological Resilience Indicators For Salt Marsh Ecosystems, Scott T. Allen, Camille L. Stagg, Jorge Brenner, Kathleen L. Goodin, Don Faber-Langendoen, Christopher A. Gabler, Katherine Wirt Ames

School of Earth, Environmental, & Marine Sciences Faculty Publications

Salt marshes are coastal ecosystems within the intertidal zone, characterized by hypoxic, saline, soil conditions and low biodiversity. Low diversity arises from frequent disturbance and stressful conditions (i.e., high salinity and hypoxia), where vegetative reproduction and low competition result in mostly monotypic stands, with some differences in plant community influenced by flooding regime (described below). While there are several types of salt marshes in the Northern Gulf of Mexico (NGoM), ranging from low to high salt marshes and salt flats (Tiner, 2013), Spartina alterniflora–dominated salt marshes in the Coastal and Marine Ecological Classification Standard (CMECS) Low and Intermediate Salt Marsh …

Ph Effect On The Formation Of Thm And Haa Disinfection Byproducts And Potential Control Strategies For Food Processing, Yen-Con Hung, Brian W. Waters, Veerachandra K. Yemmireddy, Ching-Hua Huang

School of Earth, Environmental, & Marine Sciences Faculty Publications

Chlorine-based sanitizers have seen wide spread use in food sanitation. The reaction of chlorine species with organic matter is a concern for two reasons. Available chlorine can be “used up” by organic compounds resulting in a lower amount of chlorine available for disinfection. Another concern is that some forms of chlorine can react with some organic compounds to form toxic halogenated disinfection byproducts (DBPs). Many studies have been conducted to evaluate the role of hypochlorous acid (HOCl) and hypochlorite ion (OCl−) in the production of DBPs with a particular interest in the production of trihalomethanes (THMs) and haloacetic acids (HAAs). …

Functional Predictions Of Microbial Communities In Soil As Affected By Long‐Term Tillage Practices, Janani Hariharan, Aditi Sengupta, Parwinder Grewal, Warren A. Dick

School of Earth, Environmental, & Marine Sciences Faculty Publications

Core Ideas

• Microbial function is important but difficult to assess in soil.
• An omics‐driven tool, PICRUSt, was used to characterize functions of soil microbial communities.
• No‐tillage compared with plow tillage was functionally enriched for most nutrient cycles.
• Many other functions integral to soil health can be explored by the PICRUSt omics approach.

Soil microbial communities affect the soil's biological, chemical, and physical properties, but there is still a knowledge gap regarding the long‐term impact of tillage practices on soil microbial dynamics. Additionally, the accurate identification of belowground microbial functions is a topic of active interest. In this study, microbial community …

Mechanisms Of Chinese Tallow (Triadica Sebifera) Invasion And Their Management Implications – A Review, Lauren S. Pile, G. Geoff Wang, Jeremy P. Stovall, Evan Siemann, Gregory S. Wheeler, Christopher A. Gabler

School of Earth, Environmental, & Marine Sciences Faculty Publications

Ecosystems are under increasing stress from environmental change, including invasion by non-native species that can disrupt ecological processes and functions. Chinese tallow [Triadica sebifera (L.) Small] is a highly invasive tree species in southeastern US forests, prairies, and wetlands, and effectively managing this invasive species is a significant challenge for scientists and land managers. In this review, we synthesize the literature on invasion ecology and management of Chinese tallow. Our review suggests that the invaded range of Chinese tallow is currently limited by dispersal in many areas and by low temperatures and low soil moisture, and by high soil …

Validating Sidescan Sonar As A Fish Survey Tool Over Artificial Reefs, Michael A. Bollinger, Richard Kline

School of Earth, Environmental, & Marine Sciences Faculty Publications

Visual observation methods via SCUBA are commonly used to survey artificial reef fish, although conditions in the Gulf of Mexico often make surveys difficult or even dangerous for divers. In this study, sidescan sonar was used to quantify water-column fish abundance and was compared to the established visual observation methods on SCUBA over four reef sites. Calibrated intensity values measured from sidescan sonar echo returns were used to estimate fish body length and to calculate scaled biomass (g/m2 reef) from a pooled fish length–weight relationship of commonly observed reef fish in the area. Sidescan sonar methods were equivalent to SCUBA …

Shrubs Facilitate Recruitment Of Caragana Stenophylla Pojark: Microhabitat Amelioration And Protection Against Herbivory, Li-Na Xie, Hong-Yu Guo, Zhe Liu, Christopher A. Gabler, Wei-Zhong Chen, Song Gu, Cheng-Cang Ma

School of Earth, Environmental, & Marine Sciences Faculty Publications

Key message

Mature Caragana stenophylla shrubs facilitated intraspecific sapling establishment by two mechanisms: microhabitat amelioration and protection against herbivory. Facilitation was mediated by climate, grazing, and sapling age.

Context

Pre-existing shrubs could facilitate sapling establishment of woody plants; however, how these facilitation vary across abiotic and biotic stress gradients and the underlying mechanisms remain unclear.

Aims

The aim of this study is understanding the facilitation of shrub on sapling establishment and how the two underlying mechanisms, microhabitat amelioration and protection against herbivory, vary across climatic aridity gradients, grazing gradients, and sapling age.

Methods

We conducted field sowing experiments to examine …

Capturing Species-Level Drought Responses In A Temperate Deciduous Forest Using Ratios Of Photochemical Reflectance Indices Between Sunlit And Shaded Canopies, Taehee Hwang, Hamed Gholizadeh, Daniel A. Sims, Kimberly A. Novick, Edward R. Brzostek, Richard P. Phillips, Daniel T. Roman, Scott M. Robeson, Abdullah F. Rahman

School of Earth, Environmental, & Marine Sciences Faculty Publications

Highlights

• We examine capability of spectral indices to capture isohydric/anisohydric behavior.

• We used both in-situ spectral measurements and multi-angle MODIS images.

• Only PRI could capture species-level drought responses.

• This study presents a step forward to directly mapping emergent isohydricity.

Abstract

To classify trees along a spectrum of isohydric to anisohydric behavior is a promising new framework for identifying tree species' sensitivities to drought stress, directly related to the vulnerability of carbon uptake of terrestrial ecosystems with increased hydroclimate variability. Trees with isohydric strategies regulate stomatal conductance to maintain stationary leaf water potential, while trees with anisohydric strategies allow leaf …

Nitrate Leaching From Sand And Pumice Geomedia Amended With Pyrogenic Carbon Materials, James Jihoon Kang, Marissa Davila, Sergio Mireles, Jungseok Ho

School of Earth, Environmental, & Marine Sciences Faculty Publications

There is increasing interest in using pyrogenic carbon as an adsorbent for aqueous contaminants in stormwater. The objective of this study was to investigate pyrogenic carbon materials as an amendment to geomedia to reduce nitrate leaching. Batch adsorption and column experiments were conducted to evaluate the performance of a commercial activated carbon and two biochars incorporated (5% by weight) into sand and pumice columns. The batch adsorption with 50 mg L−1 of nitrate solution showed that only activated carbon resulted in a substantial adsorption for nitrate up to 41%. Tested biochars were not effective in removing aqueous nitrate and even …

A Novel Diffuse Fraction-Based Two-Leaf Light Use Efficiency Model: An Application Quantifying Photosynthetic Seasonality Across 20 Ameriflux Flux Tower Sites, Hao Yan, Shao-Qiang Wang, Kai-Liang Yu, Bin Wang, Qin Yu, Gil Bohrer, Dave Billesbach, Rosvel Bracho, Abdullah F. Rahman, Herman H. Shugart

School of Earth, Environmental, & Marine Sciences Faculty Publications

Diffuse radiation can increase canopy light use efficiency (LUE). This creates the need to differentiate the effects of direct and diffuse radiation when simulating terrestrial gross primary production (GPP). Here, we present a novel GPP model, the diffuse-fraction-based two-leaf model (DTEC), which includes the leaf response to direct and diffuse radiation, and treats maximum LUE for shaded leaves (ɛmsh defined as a power function of the diffuse fraction (Df)) and sunlit leaves (ɛmsu defined as a constant) separately. An Amazonian rainforest site (KM67) was used to calibrate the model by simulating the linear relationship …

Linear And Nonlinear Effects Of Temperature And Precipitation On Ecosystem Properties In Tidal Saline Wetlands, Laura C. Feher, Michael J. Osland, Kereen T. Griffith, James B. Grace, Rebecca J. Howard, Camille L. Stagg, Nicholas M. Enwright, Ken W. Krauss, Christopher A. Gabler, Richard H. Day, Kerrylee Rogers

School of Earth, Environmental, & Marine Sciences Faculty Publications

Climate greatly influences the structure and functioning of tidal saline wetland ecosystems. However, there is a need to better quantify the effects of climatic drivers on ecosystem properties, particularly near climate-sensitive ecological transition zones. Here, we used climate- and literature-derived ecological data from tidal saline wetlands to test hypotheses regarding the influence of climatic drivers (i.e., temperature and precipitation regimes) on the following six ecosystem properties: canopy height, biomass, productivity, decomposition, soil carbon density, and soil carbon accumulation. Our analyses quantify and elucidate linear and nonlinear effects of climatic drivers. We quantified positive linear relationships between temperature and above-ground productivity …

Climate Controls Over The Net Carbon Uptake Period And Amplitude Of Net Ecosystem Production In Temperate And Boreal Ecosystems, Zheng Fu, Paul C. Stoy, Yiqi Luo, Jiquan Chen, Jian Sun, Leonardo Montagnani, Georg Wohlfahrt, Abdullah F. Rahman, Serge Rambal, Christian Bernhofer

School of Earth, Environmental, & Marine Sciences Faculty Publications

Highlights

• The start of net C uptake was determined by spring temperature in DBF and EF.

• Summer precipitation determined NEPmax anomalies in DBF and GRA.

• Climate controls annual NEP variability by regulating CUP and NEPmax.

Abstract

The seasonal and interannual variability of the terrestrial carbon cycle is regulated by the interactions of climate and ecosystem function. However, the key factors and processes determining the interannual variability of net ecosystem productivity (NEP) in different biomes are far from clear. Here, we quantified yearly anomalies of seasonal and annual NEP, net carbon uptake period (CUP), and the maximum daily NEP (NEPmax) …

N2o Emissions From California Farmlands: A Review, Elizabeth Verhoeven, Engil Isadora Pujol Pereira, Charlotte Decock, Gina Garland, Taryn Kennedy, Emma Suddick, William Horwath, Johan Six

School of Earth, Environmental, & Marine Sciences Faculty Publications

Of the greenhouse gases emitted from cropland, nitrous oxide (N2O) has the highest global warming potential. The state of California acknowledges that agriculture both contributes to and is affected by climate change, and in 2016 it adopted legislation to help growers reduce emissions of greenhouse gases, explicitly including N2O. Nitrous oxide emissions can vary widely due to environmental and agronomic factors with most emission estimates coming from temperate grain systems. There is, however, a dearth of emission estimates from perennial and vegetable cropping systems commonly found in California's Mediterranean climate. Therefore, emission factors (EFs) specific to California conditions are needed …

Upscaling Capillary Pressure–Saturation Functions Using Different Reference Pressure Elevations, Chu-Lin Cheng, S. Clark Cropper, Edmund Perfect, Larry Mckay, Misun Kang

School of Earth, Environmental, & Marine Sciences Faculty Publications

Choice of reference pressure elevation (RPE) on average effective saturation–capillary pressure functions, 〈〉(ψ), was investigated for monotonic drainage of homogeneous porous media. Nine columns of Flint sand with heights ranging from 4.3 to 55.0 cm were prepared. Measured 〈〉(ψ) functions were determined gravimetrically using the hanging water column method. Predicted 〈〉(ψ) functions were obtained by upscaling point function parameters determined by neutron radiographic imaging of a single drainage experiment. Bottom and midpoint RPEs resulted in the inaccurate parameterization of 〈〉(ψ) functions for tall columns. A top RPE produced accurate upscaled functions for all column heights. To evaluate the overall performance …

Impact Of Salinity Change On Water Quality Variables From The Sediment Of An Artificial Lake Under Anaerobic Conditions, Tae-Hoon Kim, James Jihoon Kang, Sang Hyun Kim, I-Song Choi, Kwang-Hyeon Chang, Jong Min Oh, Ki-Hyun Kim

School of Earth, Environmental, & Marine Sciences Faculty Publications

Artificial reservoirs are created by dike construction in coastal areas to secure the agricultural water supply on the west coast of South Korea. These systems are found to retain brackish characteristics until total desalination is achieved. To evaluate the effects of salinity on the organic substances released from the sediment, a laboratory water-sediment column experiment was conducted to assess associated changes in water quality variables such as the sediment oxygen demand (SOD), chemical oxygen demand (COD), and concentrations of nitrogen (N) and phosphorus (P). Under high salinity conditions, the release of N from the sediment was promoted with the enhancement …

Can Ecosystem Functional Recovery Be Traced To Decomposition And Nitrogen Dynamics In Estuaries Of The Lower Laguna Madre, Texas?, Mario A. Marquez, Alejandro Fierro-Cabo, Carlos E. Cintra-Buenrostro

School of Earth, Environmental, & Marine Sciences Faculty Publications

The biggest incentive to attempt the restoration and protection of estuaries is their widely acknowledged ecological and economic importance. Assessing estuary health and recovery can most accurately come from examining ecosystem processes. The purpose of this study was to explore the potential of mass loss and nitrogen (N) dynamics during leaf litter decomposition, to detect signs of functional recovery in two estuarine systems in south Texas. Submerged litterbags with black mangrove (Avicennia germinans) leaves were retrieved at various dates over 320 days. Decomposition was about 50% slower in one of the recovering systems compared to a reference site. …

Sorption Of Cr(Iii) And Cr(Vi) To K2mn4o9 Nanomaterial A Study Of The Effect Of Ph, Time, Temperature And Interferences, J. P. Valle, B. Gonzalez, J. Schulz, D. Salinas, U. Romero, Diego F. Gonzalez, Carolina Valdes, J. M. Cantu, Thomas Eubanks, Jason Parsons

School of Earth, Environmental, & Marine Sciences Faculty Publications

A Rancieite type material (K2Mn4O9) nanomaterial was synthesized and tested for the removal of chromium (III) and chromium (VI) from aqueous solutions. The synthesized nanomaterial was characterized using powder XRD and SEM. XRD showed weak diffraction peaks at only at the angles associated with K2Mn4O9. The SEM corroborated that the nanoparticles were present; however, the nanoparticles were clustered into larger aggregates. Batch studies were performed to determine the optimum pH, capacity, time dependency, interferences, and the thermodynamics of the binding. The optimum pH for the binding of Cr(III) and Cr(VI) were determined to be pH 5 and pH 2, respectively. …

Evaluation Of Sources And Patterns Of Elemental Composition Of Pm2. 5 At Three Low-Income Neighborhood Schools And Residences In Quito, Ecuador, Amit U. Raysoni, Rodrigo X. Armijos, M. Margaret Weigel, Patricia Echanique, Marcia Racines, Nicholas E. Pingitore, Wen-Whai Li

School of Earth, Environmental, & Marine Sciences Faculty Publications

Elemental characterization of fine particulate matter was undertaken at schools and residences in three low income neighborhoods in Quito, Ecuador. The three zones were located in the northern (Cotocollao), south central (El Camal), and south east (Los Chillos) neighborhoods and were classified as zones 1–3, respectively. Forty elements were quantified via ICP-MS analysis. Amongst the geogenic elements, the concentration of Si was the most abundant followed by S, Al, and Ca. Elements with predominantly anthropogenic sources such as Zn, V, and Ni were higher in zone 3 school followed by zone 2 and zone 1 schools. Enrichment factors were calculated …

Modeling The Population Effects Of Hypoxia On Atlantic Croaker (Micropogonias Undulatus) In The Northwestern Gulf Of Mexico: Part 1—Model Description And Idealized Hypoxia, Kenneth A. Rose, Sean Creekmore, Peter Thomas, J. Kevin Craig, Md. Saydur Rahman, Rachael Miller Neilan

School of Earth, Environmental, & Marine Sciences Faculty Publications

We developed a spatially explicit, individual-based model to analyze how hypoxia effects on reproduction, growth, and mortality of Atlantic croaker in the northwestern Gulf of Mexico lead to population-level responses. The model follows the hourly growth, mortality, reproduction, and movement of individuals on a 300 × 800 spatial grid of 1-km² cells for 140 years. Chlorophyll-a concentration, water temperature, and dissolved oxygen (DO) were specified daily for each grid cell and repeated for each year of the simulation. A bioenergetics model was used to represent growth, mortality was assumed stage- and age-dependent, and the movement behavior of juveniles and …

Modeling The Population Effects Of Hypoxia On Atlantic Croaker (Micropogonias Undulatus) In The Northwestern Gulf Of Mexico: Part 2—Realistic Hypoxia And Eutrophication, Kenneth A. Rose, Sean Creekmore, Dubravko Justić, Peter Thomas, J. Kevin Craig, Rachael Miller Neilan, Lixia Wang, Md Saydur Rahman, David Kidwell

School of Earth, Environmental, & Marine Sciences Faculty Publications

Quantifying the population-level effects of hypoxia on coastal fish species has been challenging. In the companion paper (part 1), we described an individual-based population model (IBM) for Atlantic croaker in the northwestern Gulf of Mexico (NWGOM) designed to quantify the long-term population responses to low dissolved oxygen (DO) concentrations during the summer. Here in part 2, we replace the idealized hypoxia conditions with realistic DO concentrations generated from a 3-dimensional water quality model. Three years were used and randomly arranged into a time series based on the historical occurrence of mild, intermediate, and severe hypoxia year types.We also used another …