Session 2D

Plastics to Plants to Teeth: Reading Earth's History

3:30 PM to 5:00 PM | Moderated by Caroline Strömberg


Comprehensive Photo Mosaicking of a Deep Sea Vent Field
Presenter
  • Casey Keegan (Casey) Hearn, Senior, Oceanography Mary Gates Scholar
Mentor
  • Harlan Paul Johnson, Oceanography
Session
  • 3:30 PM to 5:00 PM

Comprehensive Photo Mosaicking of a Deep Sea Vent Fieldclose

In 2011, a 3 week research cruise on board the R/V Atlantis was undertaken to the Endeavor segment of the Juan de Fuca spreading ridge. The main purpose of this expedition was to determine conductive heat flow from lightly sedimented sea floor within the axial valley of the spreading center (in close proximity to an isolated hydrothermal vent system). During a series of Remotely Operated Vehicle (ROV) dives to the seafloor, hundreds of heat flow time series were measured by the deployment of 13 “thermal blanket” heat flow instruments, which will enable researchers to better constrain the spatial extent of the hydrothermal fluid recharge zone. Throughout each dive, continuous video footage was recorded from several cameras on-board the ROV, along with the geographic position, altitude, heading and three dimensional orientation of the vehicle. A geological map of the sea floor across the vent field will be created using geo-referenced and orthorectified frame grabs (“flattened” onto the topography) from ROV video. The primary goal of this project is to provide a means of quantitatively measuring the porosity of spreading ridge seafloor basalt in this area of active hydrothermal venting, through the application of a technique that has never before been attempted at this scale.  A series of trigonometric algorithms were developed to use this reference information as a means of translating a still video image from ROV footage into a series of geo-referenced images.  Geographic Informatics System (GIS) software is being used to create a mosaic-like map of volcanic, biological and geological features from the sea floor near this hydrothermal vent system from these images.  An additional data layer will be produced simultaneously to provide additional information concerning the spatial extent and distribution of geologic features on the seafloor to assist in understanding the results of the heat flow study. 


Spatial and Temporal Distributions of Microplastics in Puget Sound
Presenter
  • Jessica Lorraine (Jes) Maves, Senior, Interdisciplinary Arts & Sciences (Environmental Studies), UW Tacoma, Environmental Science, UW Tacoma
Mentor
  • Julie Masura, Environmental Science, University of Washington Tacoma
Session
  • 3:30 PM to 5:00 PM

Spatial and Temporal Distributions of Microplastics in Puget Soundclose

 Plastic pollution in marine ecosystems has proven to cause damage to wildlife as well as have negative impacts on the economy and human health. Current research has been unable to accurately identify concentrations of microplastics, a subset of marine pollution, within the ocean environment. By collecting and calculating these concentrations, we can identify a correlation between microplastic marine debris and environmental conditions. Microplastics are any synthetic polymers that are less than 5mm in diameter. This study describes a 2010 comprehensive survey of microplastics within Puget Sound. Our field methods include a 15 minute surface trawl of the upper 2 to 4 centimeters of the water column. Plastics within the field samples are concentrated in the lab using wet peroxide concentration and gravimetric analysis. Every sample collected during 2010 contained plastic. Of the samples collected, concentrations in Puget Sound are as high as 422 mg plastic / g solids and as low as 2.3x 10-3 mg plastics / g solids with an average of 46 mg plastics / g solids. The concentrations vary spatially and temporally throughout the Puget Sound, and are not dependent on basin-type or location. Further studies will link these concentrations to other outside parameters including tides, weather, and watershed. Continued work will determine if the presence of plastics in the environment is increasing, decreasing, or remains the same.


Spatial and Temporal Distribution of Pollen in Sequim Bay, Washington
Presenter
  • Jerry Desmul, Senior, Environmental Science, UW Tacoma
Mentor
  • Julie Masura, Environmental Science, University of Washington Tacoma
Session
  • 3:30 PM to 5:00 PM

Spatial and Temporal Distribution of Pollen in Sequim Bay, Washingtonclose

Flora and fauna in the Puget Sound region have changed dramatically over the last hundred years due to logging, industrialization, and development. Pollen analysis is a valuable tool to learn about the historic landscape and can provide insight into paleoclimates of the region. This study, the first of its kind in this area, looks at the historic pollen distribution in the sediments of Sequim Bay, Washington. We examine the variation of historic pollen diversity with documented anthropogenic changes over time and compare current watershed conditions with surface sediment pollen diversity and distribution. In the summer of 2009, surface sediment samples were collected with a Van Veen and a two-meter core was obtained using an open barrel Kasten gravity corer. Surface samples and core samples (taken every ten centimeters) were processed to concentrate the pollen. One hundred individual pollen grains were identified in each sample to determine the concentration and variability of pollen in the bay over space and time. Pb210 analysis is being used to date the core. Surface sediment samples showed a 64% distribution of pollen from pioneer species across bay. Analyses of the core show high numbers of early successional species, such as alder and grasses, near the surface. Deeper in the core, we found pollen concentrations transition to higher numbers of pioneer species, such as hemlock and pine. Our findings illustrate changes in the flora over 150 years of non-native settlement and logging in the basin area. By understanding of the effects of these changes, conservation and restoration efforts can be measured in future analyses.


Pollen Morphology of Rhododendrons (Ericaceae) and its Potential Taxonomic and Evolutionary Significance
Presenter
  • Shaoqun (Simon) Zhou, Senior, Biology (Ecology, Evolution & Conservation) Howard Hughes Scholar
Mentor
  • Estella Leopold, Biology
Session
  • 3:30 PM to 5:00 PM

Pollen Morphology of Rhododendrons (Ericaceae) and its Potential Taxonomic and Evolutionary Significanceclose

Rhododendron is an aesthetically valuable plant genus primarily distributed in Northern hemisphere. Previous work by collectors and taxonomists has revealed that Rhododendron taxa have a scattered pattern of distribution around the globe. Yet, the evolutionary history that led to this modern distribution pattern is not well understood. Fossil records of once extant Rhododendron populations can be a key component for inferring the diversification and migration of Rhododendron. Macrofossils such as leaves and stems have more restricted requirements in their formation, and hence are rarely discovered. On the contrary, microfossils of pollen are more widely preserved and found. In this study, I explored the potential of using pollen microfossils of Rhododendron to understand how the modern distribution pattern of Rhododendrons came about. To that end, I compared and contrasted modern Rhododendron pollen from three subgenera and twenty four subsections in order to discover the degree of consistency in pollen morphology within and unique combination of traits of each taxon. All observations were performed under light microscopy. Experimental data include both structural differences and quantitative measurements. Preliminary results demonstrate promising level of variation in measurements such as the structure of apperture edges, pollen wall sculpture, overall size, and wall thickness. These palynological features are then fitted into a Rhododendron phylogeny based on molecular data to reveal any potential taxonomic significance of variation in pollen morphology. 


Convergent Evolution of Blade-Like Teeth in Mammals: Correlating Dental Complexity with Diet in Plagiaulacoid Taxa
Presenter
  • Abby Renee Vander Linden, Senior, Biology (Ecology, Evolution & Conservation) Mary Gates Scholar
Mentor
  • Gregory Wilson Mantilla, Biology
Session
  • 3:30 PM to 5:00 PM

Convergent Evolution of Blade-Like Teeth in Mammals: Correlating Dental Complexity with Diet in Plagiaulacoid Taxaclose

The evolution of a complex structure in organisms that share only a distant evolutionary history provides an opportunity to study the phenomenon of convergent evolution. One such convergent structure is a particular kind of laterally compressed blade-like shearing tooth in mammals known as a plagiaulacoid molar or premolar. Plagiaulacoid dentition has evolved independently in at least four clades of mammals: the rodent-like Mesozoic multituberculates, early primates known as carpolestids, modern and extinct South American shrew opossums, and several families of Australian diprotodont marsupials, including modern and extinct kangaroos, possums, and others. To understand the selective forces that led to the independent evolution of this specialized trait in multiple lineages, I correlated measures of tooth complexity with the known diets of modern plagiaulacoid marsupials, using this data to then infer diet in extinct taxa and compare trends in complexity among these distantly related groups of mammals. To quantify dental complexity I created 3-D digital models of the lower cheek teeth of representative taxa and used custom GIS software to generate orientation maps of the tooth surfaces. Contiguous pixels with the same orientation were then grouped into patches that approximate the number of different shearing surfaces available to mechanically process food. Orientation Patch Count (OPC) is a measure of complexity that allows me to place mammals into broad dietary categories based on the amount of plant material in the diet. This framework can be used to infer the feeding ecology of extinct mammals from digital models of fossil teeth. If the plagiaulacoid phenotype is an adaptation to similar selective pressures, I expect to find a similar range of OPC values and a similar amount of variation in complexity between plagiaulacoid clades, indicating comparable dietary range even though these groups vary widely in geographic location, temporal distribution, and evolutionary history.


Climatic Influences on Leaf Shape in Early Vascular Plants
Presenter
  • Jeffrey (Jeff) Benca, Senior, Biology (Plant) Levinson Emerging Scholar
Mentor
  • Caroline Strömberg, Biology
Session
  • 3:30 PM to 5:00 PM

Climatic Influences on Leaf Shape in Early Vascular Plantsclose

Understanding modern climate changes hinges upon our ability to assess past climates. While relatively few analogs to present climatic shifts are represented in recent geological history, the Paleozoic Era (542-251 Ma) may offer more. Investigating such transitions in the more distant past though will require expansion of existing techniques. Several methods use fossil leaf morphology to infer past climatic conditions. One such approach, DiLP (Digital Leaf Physiognomy Approach) uses leaf margin serration (toothiness) and leaf shape to infer past mean annual temperature. This technique has proven successful in using modern plant communities to estimate regional climates but can only assess past temperatures as far back as 120 Ma since it currently only utilizes leaves of recently-evolved flowering plants. However, other, more ancient groups of vascular plants have also evolved leaves with toothed margins. With toothed leaves and a fossil record exceeding 350Ma, lycopsids (clubmosses and allies) and ferns have potential to extend paleotemperature assessments back to the Late Paleozoic. To determine whether climate (in particular, temperature) influences leaf shape in living representatives of these lineages, three species of lycopsid (Lycopodium clavatum, Lycopodiella alopecuroides, and L. appressa) and two species of fern (Polystichum munitum and Blechnum brasiliense) were cultivated in a growth chamber under two temperature regimes: 15°C and 25°C, each trial lasting five months. Several leaves were selected from each specimen, laminated on overhead transparencies, and scanned for digital measures using a modified DiLP measuring protocol. While quantitative leaf measurements remain ongoing, preliminary qualitative assessment has shown that lycopsids radically change their growth habit when grown under different temperature regimes. If leaf margin toothiness or shape changes significantly in the leaves of these plants in response to temperature, fossil representatives of these ancient lineages could potentially be implemented to better assess climatic changes long-preceding the age of flowering plants.


Ecological Reconstruction of the Great Plains Region During the Late Oligocene
Presenter
  • Erik Kramer Fredrickson, Senior, Earth & Space Sciences (Physics), Physics Mary Gates Scholar
Mentor
  • Caroline Strömberg, Biology
Session
  • 3:30 PM to 5:00 PM

Ecological Reconstruction of the Great Plains Region During the Late Oligoceneclose

Many plants, as part of their growth process, accumulate groundwater-derived silica that is deposited into inter- and intracellular spaces, forming what are known as phytoliths. Due to a combination of preservational and diagnostic characteristics, phytoliths found in the fossil record serve as a powerful paleontological tool for the reconstruction of past environments and climates. For this study, rock samples containing phytoliths were collected from a site called Everson Creek in southwest Montana, once part of the Great Plains region of the United States, which spans in age from 25.3 to 24.5 million years and corresponds to an interval of warming worldwide. The samples have been processed for phytoliths using heavy liquid flotation, whereby silica bodies are separated from other material by means of their unique density. Currently, the phytoliths are in the process of being counted and divided into various diagnostic groups according to morphology. The results of these counts, when viewed in temporal order throughout the site, will shed light on the floral and climatic history of the region based on the prominent plant groups and their growth preferences. This research, which covers a time interval previously unstudied for phytoliths aims to clarify the timing of the rise to dominance of open-habitat grasses in the region, a subject that is currently disputed in the literature. The spread of grasslands is an important event in plant history because it represents the development of open habitats and is intimately linked to the expansion and evolution of various other biota. Since grasses are large producers of highly diagnostic phytoliths, any change in their ecological role will easily be seen in this study.


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