The National Park Service (NPS) Inventory and Monitoring (I&M) Program is designed to collect baseline data on “vital sign” indicators across the entire NPS system. The project presented in this thesis was designed to supplement to efforts of the Artic Network (ARCN) to catalogue the physical, chemical and biological metrics associated with the Stream Communities and Ecosystems vital sign and to foster a better understanding of the basic structure and function of these remote systems. This data is essential to assess the impacts of current and future environmental change in the ARCN parks. The primary objective of this project was to quantify the genetic diversity of microbial communities of selected arctic stream ecosystems. Microbes are a fundamentally important but poorly understood component of arctic stream ecosystems. They are responsible for recycling organic matter and regenerating nutrients that are essential to the food webs of aquatic ecosystems. Recent research (Jorgenson et al. 2002) in the ARCN parks has shown that two fundamentally different lithologies – ultramafic and non-carbonate – influence terrestrial productivity and impart different geochemical characteristics to stream water. Microbes are found in different stream habitats – sediment (epipssamon) and rock (epilithon) biofilms. In this work we test the hypothesis that these differences in lithology and stream habitat influence the genetic diversity of bacterial biofilm communities in arctic streams and whether these patterns can be correlated to stream biogeochemistry. A microbial community fingerprinting method, T-RFLP, as well as 16S rRNA gene sequencing were used to explore the genetic diversity of microbial communities in sediment and epilithic biofilms in stream reaches that drain watersheds with contrasting lithologies in the Noatak National Preserve, Alaska. Differing patterns in bacterial community composition at both the large-scale (lithology) and small-scale (stream habitat) were observed. Non-metric multidimensional scaling (NMDS) ordination of T-RFLP peaks and Analysis of Similarity (ANOSIM) showed a high degree of separation (ANOSIM P < 0.001) between the non-carbonate and ultramafic lithologies, as well as the two habitats, sediment and epilithon. Significant (P < 0.005, Bonferroni corrected) positive correlations were detected between particular nutrients, base cations, and dissolved organic carbon and bacterial community structure unique to each lithology. Although clone libraries indicated high bacterial OTU diversity within and across stream sites, biogeographical patterns were observed depending on locality type. Rarefaction analyses indicated that streams arising from the non-carbonate lithology may be more diverse than streams arising from the ultramafic lithology. Analysis of MOlecular VAriance (AMOVA) indicated that sediment and epilithon samples had genetically different microbial communities (P = 0.01) and taxonomic identifications revealed markedly different bacterial residents between sediment and epilithon habitats. Our results show relationships at large- and small-scales at the landscape level and in ecological niches within a single stream.

Halogen chemistry in the polar boundary layer has received much scientific attention in recent years due to the observations of high concentrations of reactive halogens in springtime. The source of reactive halogens and the site for halogen activation remain a subject of debate. In this thesis, chloride, bromide and sodium ions across the snow-sea ice-seawater interface were measured to study the cryospheric halide distribution and halogen activation in the Arctic. The results show halides/Na+ molar ratios (Br−/Na+ and Cl−/Na+ ratios) in snow are commonly higher than that in seawater, suggesting snow scavenges halides from sources other than sea salt. The decrease in the halides/Na+ ratios in the surface snow layer indicates a loss of halides from the snow, supporting snow as an important substrate for halogen activation. Furthermore, a mechanism for snow-assisted halogen activation is proposed based on the variation of the Br−/Cl− ratio in the snow. / October 2015

This dissertation focuses on the distribution, reproduction, and transport of zooplankton in the Chukchi and Beaufort seas and adjacent Canada Basin. Specifically, it analyzes 1) the species-specific distribution of copepod nauplii as it is forced by the surface layer mesoscale circulation and physical properties, 2) the reproduction of the dominant copepod Calanus glacialis in the western Arctic, and 3) the effects of eddy transport on the zooplankton community in the Chukchi and Beaufort seas and Canada Basin. To achieve this I adapted a molecular identification method to work with small crustaceans. The method was successfully used to generate a sequence database from adult copepods of species present in the region. Differences in the D1/D2 domains of the large subunit ribosomal were sufficient for the identification of all species present in the western Arctic with the exception of two sibling Calanus copepods which were discriminated using the mitochondrial cytochrome oxidase I gene. The application of this semi-robotic protocol to selected surface samples collected from the USCGC Healy in summer 2004 revealed that four copepod species dominated the naupliar community: Oithona similis, C. glacialis, Pseudocalanus minutus, and P. mimus. Each species had different abundance and distribution patterns related to their specific life cycles and environmental affinities. The molecular identification method was then applied to study the egg production rates of C. glacialis and differentiate it from C. marshallae. This work validated reported spatial and seasonal variations in egg production rates in C. glacialis and showed that an increase in primary production in summer 2004 compared to summer 2002 did not result in an increase in secondary production of this copepod. The last component of this study is the result of a unique sampling design to study shelf-basin interactions. The results provided evidence of on-shelf transport of basin organisms by a wind-induced upwelling event and of eddy-mediated advection of zooplankton from the surrounding shelves into the Arctic basin. Overall, this study integrated new molecular tools and unusual sampling opportunities to advance our understanding of the role zooplankton in this Arctic ecosystem.

Inaug.-diss.--Greifswald. / Lebenslauf. "Literaturverzeichnis": p. 65-67.

This work presents the first comprehensive study of Hg dynamics within Arctic multiyear sea ice, followed by a mechanistic study of Hg behaviour in new and growing experimental sea ice. Multiyear sea ice taken from the eastern Beaufort Sea and McClure Strait showed total Hg concentrations ranging from 0.12 to 12.2 ng L-1. Both vertical distribution patterns and regional differences can be explained by the sources and dynamics of particulate matter in sea ice. Methylated mercury was measured in Arctic sea ice: ratios of methylated to total Hg reached 0.4 within bottom ice, suggesting the potential occurrence of in situ methylation in sea ice. The dominant role of particulate dynamics in controlling Hg distribution in sea ice was supported by a mesocosm-scale study at the Sea-ice Environmental Research Facility. This suggests that melting multiyear sea ice represents a considerable loading of total and methylated Hg into the Arctic Ocean.

The biological remains preserved in the sediments of Arctic lakes and ponds in the Canadian High Arctic are important indicators of environmental change, especially as long-term instrumental data are often lacking. Although recent studies have underscored variability amongst these aquatic ecosystems, data are lacking from several key ecosystems. This thesis addresses some of these critical knowledge gaps in the Canadian high Arctic, using diatom-based limnological and paleolimnological techniques. First, I explore the limnology and diatom ecology along a gradient of bioclimatic zones on Melville Island in the western High Arctic. Lakes and ponds located in the most lushly vegetated zone were significantly different from those elsewhere on the island, both in terms of measured limnological variables and in terms of diatom assemblage composition. Diatom species distributions from Melville Island can best be explained by differences in pH and related variables. Secondly, ponds and lakes located in a High Arctic oasis on northern Ellesmere Island, recorded significantly higher specific conductivity, nutrients, and dissolved organic carbon than freshwater bodies from the surrounding polar desert. In Chapter 5, I provide an examination of long-term environmental change from Melville Island, a region of the High Arctic for which no paleolimnological data exist. The timing of diatom shifts in a dated sediment core from a small pond is consistent with the onset of climate warming in the early 20th century. Differences in ice cover have often been invoked to explain differences in the timing and magnitude of diatom shifts in the Arctic, but this hypothesis has not been explicitly tested. In Chapter 6, I compare two adjacent lakes with similar physical characteristics but different ice cover regimes from northern Ellesmere Island. I provide strong evidence that extended ice cover dampens diatom community responses to environmental change. In the final chapters, I determine that marine-derived nutrients significantly affect the limnology of ponds on Cape Vera, Devon Island, and are related to the degree of seabird influence. Although a portion of diatom species distributions can be linked to seabird influence, the most abundant taxa show little relation to the nutrient gradient. In a paleolimnological context, diatoms are not robust indicators of seabirds in High Arctic ponds. / Thesis (Ph.D, Biology) -- Queen's University, 2007-09-13 19:30:46.991

No description available.

A 2007 survey of muscid flies from Churchill, Manitoba, Canada, yielded 155 species. The diversity of this contemporary assemblage was compared to that of an historical (pre-1965) assemblage. Few differences were found between assemblages for material collected by net sweeping and most non-overlapping species between time periods were rare in samples and/or collected by different methods. DNA barcoding was used as a tool to assist with the identification of Muscidae specimens. Performance of the cytochrome c oxidase subunit 1 gene (COI) in the discrimination of muscid species was assessed and correspondence levels of 98.6% were established between species limits recovered by DNA barcode clusters and morphology. I conclude that the great majority of species limits currently accepted in the literature are adequate for Muscidae and that DNA barcoding is a useful identification tool for this family.

The distribution of the partial pressure of surface water CO2 (pCO2sw) was measured throughout the Canadian Arctic Archipelago and Baffin Bay during the summer and fall. Throughout these two seasons, values ranged from 110 μatm and 436 μatm, demonstrating the high level of variability in pCO2sw across the archipelago. Surface waters remained undersaturated compared to atmospheric pCO2 (~386 μatm) for the majority of the sampling period. Generally, areas in which remnant sea ice was melting were observed to be the most undersaturated, whereas warm, ice-free waters in proximity to rivers were supersaturated with respect to atmospheric pCO2. These observations demonstrate how the influence of freshwater from sea ice melt and rivers affect pCO2sw differently. The region was found to act as an overall sink, absorbing on average 17.6 mmol CO2 m-2 day-1 throughout the two seasons. Seasonally specific factors controlling pCO2sw and their effects through a warming climate are discussed.

A 2007 survey of muscid flies from Churchill, Manitoba, Canada, yielded 155 species. The diversity of this contemporary assemblage was compared to that of an historical (pre-1965) assemblage. Few differences were found between assemblages for material collected by net sweeping and most non-overlapping species between time periods were rare in samples and/or collected by different methods. DNA barcoding was used as a tool to assist with the identification of Muscidae specimens. Performance of the cytochrome c oxidase subunit 1 gene (COI) in the discrimination of muscid species was assessed and correspondence levels of 98.6% were established between species limits recovered by DNA barcode clusters and morphology. I conclude that the great majority of species limits currently accepted in the literature are adequate for Muscidae and that DNA barcoding is a useful identification tool for this family.