Earth and Environmental Systems
http://hdl.handle.net/10484/5627
2024-03-29T06:52:15ZTHE ECOLOGY, BIOGEOCHEMISTRY AND PHYLOGENY OF METHANE SEEP AND NON-SEEP BENTHIC FORAMINIFERA FROM THE PACIFIC MARGIN
http://hdl.handle.net/10484/12688
THE ECOLOGY, BIOGEOCHEMISTRY AND PHYLOGENY OF METHANE SEEP AND NON-SEEP BENTHIC FORAMINIFERA FROM THE PACIFIC MARGIN
Burkett, Ashley M.
In an effort to understand the relationships between active methane seep and adjacent
non-seep (inactive) populations of the deep-sea foraminifera Cibicidoides wuellerstorfi, a
common paleo-indicator species, from methane seeps in the Pacific were analyzed and
compared to one another for genetic similarities of small subunit rDNA (SSU rDNA)
sequences. Pacific Ocean C. wuellerstorfi were also compared to those collected from other
localities around the world (based on 18S gene available on Genbank, e.g., Schweizer et al.,
2009). Results from this study revealed that C. wuellerstorfi living in seeps near Costa Rica and
Hydrate Ridge are genetically similar to one another at the species level. Individuals collected
from the same location that display opposite coiling directions (dextral and sinistral) had no
species level genetic differences. Comparisons of specimens with genetic information available
from Genbank (SSU rDNA) showed that Pacific individuals, collected for this study, are
genetically similar to those previously analyzed from the North Atlantic and Antarctic. These
observations provide strong evidence for the true cosmopolitan nature of C. wuellerstorfi and
highlight the importance of understanding how these microscopic organisms are able to
maintain sufficient genetic exchange to remain within the same species between seep and nonseep
habitats and over global distances.
Although organic matter degradation rates have been studied for some time, in situ rates
of protoplasm degradation in deep-sea foraminiferal tests have been estimated based on
laboratory experiments and sediment distribution patterns. Information regarding degradation rates of foraminiferal protoplasm is essential in the use of non-vital stains in identifying the
amount and character of protoplasm in tests which remains the most commonly used method to
assess living populations of benthic foraminifera (e.g., Murray and Bowser, 2000). In an effort
to examine the retention potential of foraminiferal protoplasm on the deep seafloor 36 frozen,
protoplasm filled Cibicidoides wuelllerstorfi were placed in natural sediments inside
experimental containers and deployed on for 390 to 396 days. Despite oxygen-poor conditions
(0.24 mL/L to 0.37 mL/L) that would be expected to promote preservation of organic matter,
and experimental container protection from macro- and megafauna, 72% of deployed tests
containing protoplasm were destroyed beyond recognition within 396 days. Of the 10
specimens (28%) recovered, 9 retained at least some protoplasm, but only 1 individual had the
potential to be identified as living based on Rose Bengal staining techniques. However, in this
specimen, protoplasm was clearly altered or missing in some chambers. The results of this study
suggest that it is unlikely that many, if any, benthic foraminiferal specimens containing
protoplasm terminated by freezing would be conservatively considered as recently living using
Rose Bengal as an indicator of the extent and character of protoplasm within the test after 396
days or less exposed to in situ conditions in deep-seafloor habitats.
After 390 to 396 days on the seafloor at Hydrate Ridge in the Pacific, eight artificial
substrate experiments (hereafter referred to as SEA3 for Seafloor Epibenthic Attachment Cubes)
were colonized by 1058 Cibicidoides wuellerstorfi. The presence of this species has been
inferred as an indicator of well-oxygenated conditions, and recruitment of such large numbers in
bottom-waters with low dissolved oxygen availability (0.24 to 0.37 mL/L) indicates that this
taxon is not as limited by oxygen as previously thought. Clues about substrate preferences were
also evident from the distribution of individuals on SEA3. For example, the wooden rod attached directly to the plastic mesh that was heavily colonized was devoid of any epibenthic
foraminifera. Few studies have examined foraminiferal colonization of hard substrates in the
deep-sea (e.g., Mullineaux, 1987), and to our knowledge no previous study has compared
foraminiferal colonization of seep with non-seep substrates. Comparisons of abundance, size
distribution, and isotopic biogeochemistry of living foraminifera colonizing experimental
substrates revealed differences between seep and non-seep environments. SEA3 within active
methane seep habitats at Hydrate Ridge contained significantly fewer (406 on four SEA3s a
density of 44 #individuals/100 cm2) individuals compared with those in adjacent off-seep sites
(594 on three SEA3s a density of 86 #individuals/100 cm2). An additional 58 individuals were
on a SEA3 22, which may have experienced seep conditions despite being deployed as a nonseep
experiment (density of 25 #individuals/100 cm2). This difference in abundance may be due
to active seepage conditions, however, reduced foraminiferal abundances on SEA3s located at
seeps resulted from increased predation and displacement by higher abundances of macro- and
meiofauna observed at active seep locations. Stable carbon isotope values of benthic
foraminifera from seep substrates ranged from 0.26‰ to -0.56‰ with an average of 0.03‰
while δ13C from off-seep substrates range from 0.39‰ to -0.26‰ with an average of 0.15‰.
Statistical analyses indicate a significant difference between seep and non-seep δ13C. Stable
oxygen isotopes of foraminiferal carbonate from seep substrates range from 2.70‰ to 2.03‰
with an average of 2.41‰ and 2.65‰ to 1.99‰ with an average of 2.39‰ at adjacent off-seep
sites. These results provide some of the first information about epifaunal foraminiferal
colonization potential at methane seeps and highlight the biogeochemical and ecological
influences of seep habitats on C. wuellerstorfi.
2015-05-01T00:00:00ZAlternative Ways to Enumerate Data on Race in Puerto Rico: Are Racial Segregation and Spatial Clustering more Evident when Using a Culturally Grounded Methodology?
http://hdl.handle.net/10484/12645
Alternative Ways to Enumerate Data on Race in Puerto Rico: Are Racial Segregation and Spatial Clustering more Evident when Using a Culturally Grounded Methodology?
Allen, Reuben
Nationalist discourse concerning race in Puerto Rico generally states that residents are of the
same racially mixed heritage—a combination of Spanish, West African, and indigenous ancestry
of various degrees. However, literature and casual observations suggest that the population is
characterized by greater variation in physical appearances than what is posited by “admixture”
discourse. Moreover, and further complicating the understanding of race, 2010 U.S. Census data
show that over 75 percent of Puerto Ricans self-identified as “White, alone”, and that only 3.3
percent of respondents indicated “Two or More Races.” Researchers, employers, and
governmental agencies attempting to address or further analyze issues of inequality,
discrimination, and residential segregation have had to rely on existing U.S. Census data to
identify possible links between race and socioeconomic attainment. Thus, the need for an
alternative data collection process that can be used for various forms of socioeconomic and
spatial analysis has become evident. In this study, I administered alternative datasets that
emphasized a locally suited, culturally grounded, and standardizable conceptual foundation for
the purpose of establishing more representative racial statistics for the Puerto Rican population.
The socioeconomic and spatial implications of resulting data were analyzed to determine if
members of certain racial classifications are more privileged than others, and to determine if
racial identity is characterized by spatial autocorrelation. Results showed that “Whites”, defined
by different enumerators through various instruments, have attained slightly higher levels of
socioeconomic attainment than nonwhites. However, there were no indications of spatial
clustering or segregation based on race. Lastly, I interviewed a subsample of participants to garner feedback concerning their assessments of the survey instruments, their general
understanding of race and historical admixture, their perceptions of racial inequality, their
opinions of affirmative action, and finally, their observations of racialized spaces.
2014-08-01T00:00:00ZURBAN FLASH FLOOD RISK ASSESSMENT AND INUNDATION MODEL UTILIZING GIS FOR TERRE HAUTE, INDIANA
http://hdl.handle.net/10484/12626
URBAN FLASH FLOOD RISK ASSESSMENT AND INUNDATION MODEL UTILIZING GIS FOR TERRE HAUTE, INDIANA
Ishman, Zachary Scott
Use of ArcGIS to examine flash flooding variables and produce a flash flood risk
assessment and inundation model for Terre Haute, Indiana. Risk assessment, produced within
ArcGIS, indicates that an increase in developed area leads to an increase in very high flash flood
risk area and majority of very high risk area resides in developed areas of Terre Haute.
Inundation model, produced using ArcGIS and Python, indicates that the proposed model can
determine locations of flash flooding, but spatial extent of model predicted flooding is not
reliable based on field validation.
2014-08-01T00:00:00ZMulti-Timescale Dynamics of Land Surface Temperature
http://hdl.handle.net/10484/12625
Multi-Timescale Dynamics of Land Surface Temperature
Fu, Peng
Spatial and temporal patterns of land surface temperature (LST) have been used in studies of surface energy balance, landscape thermal patterns and water management. An effective way to investigate the landscape thermal dynamics is to utilize the Landsat legacy and consistent records of the thermal state of earth’s surface since 1982. However, only a small proportion of studies emphasize the importance of historical Landsat TIR data for investigating the relationship between the urbanization process and surface thermal properties. This occurred due to the lack of standardized LST product from Landsat and the unevenly distributed remote sensing datasets caused by poor atmospheric effects and/or clouds. Despite the characterization of annual temperature cycles using remote sensing data in previous studies, yet the statistical evidence to confirm the existence of the annual temperature cycle is still lacking. The objectives of the research are to provide statistical evidence for the existence of the annual temperature cycle and to develop decomposition technique to explore the impact of urbanization on surface thermal property changes. The study area is located in Los Angeles County, the corresponding remotely sensed TIR data from Landsat TM over a decadal year (2000-2010) was selected, and eventually a series of 82 cloud-free images were acquired for the computation of LST. The hypothesis technique, Lomb-Scargle periodogram analysis was proposed to confirm whether decadal years’s LSTs showed the annual temperature cycle. Furthermore, the simulated LSTs comprised of seasonality, trend, and noise components are generated to test the robustness of the decomposition scheme. The periodogram analysis revealed that the annual temperature cycle was confirmed statistically with p-value less than 0.01 and the identified periodic time at 362 days. The sensitivity analysis based on the simulated LSTs suggested that the decomposition technique was very robustness and able to retrieve the seasonality and trend components with errors up to 0.6 K. The application of the decomposition technique into the real 82 remote sensing data decomposed the original LSTs into seasonality, trend, and noise components. Estimated seasonality component by land cover showed an agreement with previous studies in Weng & Fu (2014). The derived trend component revealed that the impact of urbanization on land surface temperature ranged from 0.2 K to 0.8 K based on the comparison between urban and non-urban land covers. Further applications of the proposed Lomb-Scargle technique and the developed decomposition technique can also be directed to data from other satellite sensors.
2014-08-01T00:00:00Z