Exploring Multi-scale Variation of Fish Community Diversity in a Dynamic Coastal Estuary

Examining diversity over multiple spatial and temporal scales affords the opportunity to develop a mechanistic understanding of the factors influencing community diversity dynamics, and how these may shift in a changing world. This thesis first examines multi-decadal fish community diversity metrics across a coastal biogeographic transition zone to quantify changes in species assemblages, assess relationships between fish community diversity and the abiotic environment, and capture potential shifts in the location of a putative biogeographic break. Results of this chapter indicate not only a change in fish community composition, but also a shift in the location of the biogeographic transition zone. If these trends continue, a potential 16-62km shift northward by the year 2100 could occur. Understanding the novel species assemblages these shifts could result in is necessary for the future management of this area. Next this thesis examines diversity on a local scale, assessing the response of the fish community to restoration of oyster reefs and coastal wetlands which act as essential fish habitat. Results support the idea that fish community composition at restored oyster reefs is more similar to those of live reefs than dead reefs, however, results of abundance and diversity analyses were equivocal. Living shoreline analyses produced no differences between control and restored sites before or after restoration. Possible explanations for lack of clear trends in the fish community could be explained by the presence of other essential fish habitats in the area, scale of restoration, and length of monitoring. This thesis explores diversity on a multitude of spatial and temporal scales to better understand how fish communities respond to change and generates fundamental knowledge that can improve our ability to conserve and manage coastal communities and better inform the development of ecosystem-based management strategies

The relative age and paleoclimatic implications of a sand dune in Amboy, Illinois

Includes bibliographical references (pages [46]-49)Research on currently inactive dunes in Colorado and Nebraska reveals th a t they formed during widespread Holocene episodes of dune activity. This study focuses on the relative age of inactive dunes in northern Illinois on the late Wisconsinan Bloomington Moraine. If these dunes were active during the Holocene, they could be an important geomorphological proxy for Holocene climate change. Soils on one dune and in adjacent loesscovered areas were studied to determine the relative degree of soil development and to identify any buried soils under the dune. Ten soil profiles were described and analyzed for particle size, color, pH, and other physical properties. Wind speed and climatic data from a nearby station were used to calculate a mobility index and a sand rose to quantify the potential for eolian sand movement. The result was th a t there was enough wind energy for sand movement; however the P/PE is high enough for stable vegetation cover and therefore stable dunes. The orientation of the dunes indicates northwest winds during their formation. Soils in the dune sand and in the loess both have clay accumulations in Bt horizons, although those in the dune sand are much more weakly developed. This may reflect differences in parent material rath e r th an age. The presence of a Bt horizon indicates the soils are more than a few hundred years old, probably significantly older. There are no buried soil horizons under the dune, which rests on unweathered late Wisconsinan glacial till. This means the sands were deposited not long after the till or if there were soils on the till before the sands, they were completley eroded away before the sands migrated in. It is concluded th a t the dune most probably formed more than 10,000 years B.P., under cold climate conditions, rather than during warm, dry parts of the Holocene.M.S. (Master of Science

A multi-tiered assessment of fish community responses to habitat restoration in a coastal lagoon

Essential fish habitat is critical for foraging, breeding, or as refugia. As such, restoration of these habitats has the potential to increase the diversity and abundance of fishes. Here, we explored how fish communities responded in the first 12-24 mo following oyster reef restoration. Study sites included 8 restored reefs plus 4 live and 4 dead reefs as controls. Oyster reef metrics (e.g. density, height, thickness) and fish abundance and diversity metrics were quantified, including species richness, Shannon diversity, Simpson's diversity, and Pielou's evenness. Species composition was explored further to identify indicator species and assess habitat preferences. Patterns of fish community diversity and species composition were compared to oyster reef metrics to discern what oyster reef characteristics best predict fish diversity. Results showed that intertidal oyster reefs were structurally restored and shifted from resembling negative control reefs to positive control reefs within 12-24 mo. Across all treatment types, oyster shell height and reef thickness were the best predictors of fish diversity. However, at the fish community level, assemblages at restored reefs were similar to those at positive and negative controls. Species-level analyses suggest treatment types have unique indicator species, including Chilomycterus schoepfi (striped burrfish) for dead reefs, Lutjanus synagris (lane snapper) for restored reefs, and Gobiosoma robustum (code goby) for live reefs. This work suggests fishes can be used as higher trophic level indicators of restoration success, and ecosystem-based approaches, such as habitat restoration, can restore essential fish habitat, thus benefiting fish communities while moving coastal ecosystems toward sustainability

A Global Population Genetic Study of Pantala flavescens

Among terrestrial arthropods, the dragonfly species Pantala flavescens is remarkable due to their nearly global distribution and extensive migratory ranges; the largest of any known insect. Capable of migrating across oceans, the potential for high rates of gene flow among geographically distant populations is significant. It has been hypothesized that P. flavescens may be a global panmictic population but no sufficient genetic evidence has been collected thus far. Through a population genetic analysis of P. flavescens samples from North America, South America, and Asia, the current study aimed to examine the extent at which gene flow is occurring on a global scale and discusses the implications of the genetic patterns we uncovered on population structure and genetic diversity of the species. This was accomplished using PCR-amplified cytochrome oxidase one (CO1) mitochondrial DNA data to reconstruct phylogenetic trees, a haplotype network, and perform molecular variance analyses. Our results suggested high rates of gene flow are occurring among all included geographic regions; providing the first significant evidence that Pantala flavescens should be considered a global panmictic population. © 2016 Troast et al

Minimum Spanning Haplotype Network.

<p>All haplotypes are based on the CO1 gene except for “India 4” which is “CO1-like”. Numbers in parentheses indicate the number of changes between haplotypes.</p