Honors Theses (Biology)
https://scholarsbank.uoregon.edu/xmlui/handle/1794/3627
2024-03-29T06:46:41ZEFFECTS OF FLOW VELOCITY AND SETTLEMENT LOCATION ON GROWTH RATES OF EARLY JUVENILES OF THE PEDUNCULATE BARNACLE, POLLICIPES POLYMERUS, SOWERBY 1833
https://scholarsbank.uoregon.edu/xmlui/handle/1794/26919
EFFECTS OF FLOW VELOCITY AND SETTLEMENT LOCATION ON GROWTH RATES OF EARLY JUVENILES OF THE PEDUNCULATE BARNACLE, POLLICIPES POLYMERUS, SOWERBY 1833
Everson, Hannah N.
The intertidal lepadomorph barnacle, Pollicipes polymerus, is known for its propensity to
aggregate in rosette-shaped or irregular clusters. The gregarious lifestyle is ensured by the
species’ settlement preference. Cyprids of P. polymerus settle almost exclusively on the peduncle
of adult conspecifics, while settlement in cracks and crevices and on acorn barnacles is rare. For
gregarious settlement behavior to evolve and persist, individuals should gain some benefit that
would otherwise not be achieved with a solitary lifestyle - such as defense against predators
(Riipi et al. 2001) or to facilitate cross-fertilization (Wu 1981) Due to increasing demand for P.
polymerus in culinary markets, the gregarious settlement behavior makes them particularly
susceptible to overharvesting. This study examines whether gregarious settlement results in
higher growth rates of juveniles compared to growth of solitary individuals. I asked if and how
P. polymerus gains in overall fitness from gregarious settlement. I address two questions: 1) Is
the growth rate of early juveniles dependent on the velocity of water in which they feed? and 2)
Does settlement on conspecifics benefit early juveniles by increasing growth rate? Two treatment
groups (solitary and gregarious) were studied, with individuals ranging in size from 1mm - 3mm
rostro-carinal length. An apparatus, utilizing a rotating disc, was constructed to create a range of
experimental velocities. For two trials carried out in a marina environment (trial 1 and 2), growth
rates ranged from 0.1mm - 1.2mm/wk at any given velocity. For two trials in a tank environment
(trials 3 and 4) individual growth never exceeded 0.6mm/wk. Overall results indicate that neither
current velocity nor settlement location had consistent effects on early juvenile growth rates. In
the tank environment, where food concentrations were lower, velocity had a significant negative
effect on the growth rate of gregarious but not solitary juveniles. In only 1 of 4 trials, settlement
on a conspecific had a significant positive effect on average juvenile growth. The absence of
consistent trends within and across trials together with few significant results indicate that
velocity and settlement location for early juveniles may not be primary factors in gregarious
settlement of this barnacle. Other factors or these factors at different life stages may account for
settlement behavior. My findings also suggest that aquaculture of these barnacles does not
require specific flow speeds or adult substrata to cultivate newly settled barnacles.
18 pages
2021-11-10T00:00:00ZThe Distribution of Two Marine Cladocerans During Upwelling and Relaxation Events Off the Oregon Coast
https://scholarsbank.uoregon.edu/xmlui/handle/1794/22765
The Distribution of Two Marine Cladocerans During Upwelling and Relaxation Events Off the Oregon Coast
Thomas, Kate
Offshore surface currents that appear during upwelling events have the potential to carry nearshore coastal zooplankton offshore. I tested the hypothesis that the marine cladocerans Podon leuckarti and Evadne nordmanni are pushed offshore during summer upwelling. Additionally, stratified horizontal currents during upwelling, with surface regions moving offshore and deeper layers moving onshore, could differentially distribute reproductive stages or sizes that have different vertical distributions. I tested the hypothesis that reproductive stages and sizes of cladocerans would be distributed differentially from one another during upwelling and relaxation events. The fecundity of marine cladocerans off Oregon was also investigated. A vertically stratified transect of 7 stations located from 0.5 to 28 km offshore near Coos Bay, Oregon was sampled for zooplankton on four days in the summer of 2007. Two of the sample dates (27 June and 14 August) were characterized by upwelling conditions, and two (3 and 18 July) were characterized by relaxation or weak downwelling conditions. Preserved cladocerans were counted, measured, and assigned a reproductive stage. In females the number of embryos was counted. Neither cladoceran species showed evidence of offshore surface
transport during upwelling, and both showed densest concentrations nearshore, although a deeper offshore concentration of E. nordmanni may have been affected by deep onshore upwelling currents. Parthenogenic P. leuckarti with early embryos were distributed similarly to those with advanced embryos, and males tended to stay near the bottom or surface nearshore. All stages of E. nordmanni stayed primarily near the bottom or surface nearshore. Smaller cladocerans and parthenogenic females with early embryos were found in larger proportions closer to shore, while larger cladocerans and parthenogenic females with advanced embryos were found farther offshore. Cladoceran fecundity in Oregon was high, with a mean and 95% confidence interval of 5.42±0.37 embryos per parthenogenic P. leuckarti and 10.21±0.247 embryos per parthenogenic E. nordmanni. Complex interactions between physical oceanography and cladoceran behavior may account for observed cladoceran distributions off the Oregon coast.
90 pages
2010-11-01T00:00:00ZThe subtidal Bryozoan fauna off Cape Arago, Oregon
https://scholarsbank.uoregon.edu/xmlui/handle/1794/22764
The subtidal Bryozoan fauna off Cape Arago, Oregon
Cottrell, Dylan
The subtidal marine biodiversity off the Oregon coast is poorly studied and not well understood. The few subtidal studies in Oregon have focused on vertebrates with little regard to invertebrate assemblages. Oregon’s subtidal Bryozoa play key roles in these assemblages by providing habitat, food, and, potentially, pollution sequestration. Using dredge samples collected over two years, we assembled a comprehensive list of Bryozoa found between 30-60 m depth off Cape Arago, Oregon. A total of 41 species were collected, including one new species in the genus Fenestruloides. Although 25 families were represented in our samples, 17 (68%) families were only represented by one species and only two families (8%) were represented by more than three species. This data provides the first comprehensive survey of Oregon’s subtidal bryozoan biodiversity and is an important first step in understanding the region’s biodiversity.
83 pages
2013-05-01T00:00:00ZThe role of uxs1 in chondrocyte organization, morphogenesis, and signaling pathways during skeletogenesis
https://scholarsbank.uoregon.edu/xmlui/handle/1794/4478
The role of uxs1 in chondrocyte organization, morphogenesis, and signaling pathways during skeletogenesis
Smith, Gabriel
The role proteoglycans play in molecular-genetic mechanisms of skeletogenesis is not completely understood. UDP-glucuronic acid decarboxylase 1 (Uxs1) converts UDP-glucuronic acid to UDP-xylose which is used by xylosyltransferase 1 to initiate assembly of a common tetrasaccharide linker critical to the biosynthesis of chondroitin sulfate, dermatan sulfate, and heparan sulfate proteoglycans, all of which are found in abundance within the extracellular matrix of cartilage. In this paper, we present two alleles, hi3357 and mow, that have mutations in uxs1. Zebrafish embryos with uxs1 mutations presented an absence of Alcian staining from cells in the pharyngeal cartilages. Fluorescent confocal microscopy revealed improper chondrocyte organization and morphogenesis in cartilage elements of the neurocranium and pharyngeal skeleton. Additionally, we observed reductions in Alizarin red staining at endochondral and intramembranous ossification centers indicating improper bone development. Whole-mount in situ hybridization experiments revealed uxs1 expression to be ubiquitous in developing embryos until 2 dpf and thereafter localized to the pharyngeal skeleton, suggesting a critical role for uxs1 expression during skeletogenesis. These results suggest that chondrocyte organization and morphogenesis, endochondral ossification, and intramembranous ossification are all dependent upon uxs1 function. In mutants homozygous for uxs1hi3357 and uxs1mow, wheat germ agglutinin staining revealed a reduction in proteoglycans in the extracellular matrix. Moreover, antibodies against heparan sulfate revealed deletion of heparan sulfate proteoglycans in the pharyngeal cartilage elements. The deletion of heparan sulfate proteoglycans in uxs1 mutants suggests that Wnt, Fibroblast growth factor, or Hedgehog signaling cascades may be disrupted as previously shown to occur in the fruit fly Drosophila. These findings reveal an absence of UDP-xylose dependent proteoglycans from the extracellular matrix due to mutations in uxs1. Experiments also showed a deletion of type II collagen from the extracellular matrix of chondrocytes, suggesting a role for Uxs1 or proteoglycans in the secretory or localizing mechanisms. Additionally, expression of col10a1 was absent from endochondral ossification centers and reduced at intramembranous sites, suggesting that uxs1 is necessary for proper reciprocal signaling pathways between perichondrial cells and chondrocytes critical for bone formation. Thus, we conclude that UDP-xylose dependent proteoglycans are absent in uxs1 mutants which is altering the composition of the extracellular matrix and disrupting reciprocal signaling between cells. This study provides new insight into the role proteoglycans play in skeletogenesis and the evolutionarily conserved role of uxs1 across life on earth.
A THESIS Presented to the Department of Biology and the Clark Honors College of the University of Oregon in partial fulfillment of the requirements for degree of Bachelor of Science, Spring 2007.
2007-07-13T02:14:01Z