A newly discovered fern-like fossil plant is described from the Lower Upper Devonian of southern Ellesmere. This plant occurs as an element of an Archaeopteris dominated flora preserved in sediments of the Nordstrand Point Formation (mid-late Frasnian) at Bird Fiord. The plant demonstrates a pinnate vegetative system with three orders of branch and laminate pinnules, of a general sphenopteroid type. Primary pinnae usually diverge from the main axis in distichous pairs (Le., in a quadriseriate manner), but rarely depart singly (i.e., in a biseriate manner). Each primary pinna bears an aphlebia in the catadromic position. Laminate pinnules are broadly lobed with a proximally overtopped vein system. Anatomically, this plant is characterized by an elongate, mesarch, bipolar protostele that is ribbon to clepsydroid in shape. Proximal to each primary pinna node, an initially crescent-shaped, bipolar pinna trace diverges from the main axis stele. This trace appears to become four-ribbed before dividing to yield a pair of bipolar primary pinna traces. A pair of circular, centrarch aphlebia traces depart from the catadromic ribs of a primary pinna trace in its four-ribbed stage. Protoxylem is helically thickened, with metaxylem pitting ranging from scalariform to circular. Secondary xylem is unknown. Both the morphology and anatomy of this plant are non-gymnospermous and suggest affinity instead with zygopterid ferns. Within the Zygopteridales, this plant seems to align most closely with the Rhacopytaceae. The Frasnian dating of this plant suggests that laminated foliage had been achieved by some zygopterid ferns long before previously recognized. The presence of Sphenopteris-like pinnules in this Frasnian plant also shows that one should be careful in attributing such foliage to early gymnosperms. / Master of Science

We explored the combination of metagenomic library and DNA microarray technologies into a single platform as a novel way to rapidly screen metagenomic libraries for genetic targets. In the "metagenomic microarray" system, metagenomic library clone DNA is printed on a microarray surface, and clones of interest are detected by hybridization to single-gene probes. This study represents the initial steps in the development of this technology. We constructed two 5,000-clone large-insert metagenomic libraries from two diesel-contaminated Arctic soil samples. We developed and optimized an automated fosmid purification protocol to rapidly-extract clone DNA in a high-throughput 96-well format. We then created a series of small prototype arrays to optimize various parameters of microarray printing and hybridization, to identify and resolve technical challenges, and to provide proof-of-principle of this novel application. Our results suggest that this method shows promise, but more experimentation must be done to establish the feasibility of this approach.

No description available.

This study presents a comprehensive overview of the current state of the Milne Ice Shelf and how it has changed over the last 59 years. The 205 ±1 km2 ice shelf experienced a 28% (82 ±0.8 km2) reduction in area between 1950 – 2009, and a 20% (2.5 ±0.9km3 water equivalent (w.e.)) reduction in volume between 1981 – 2008/2009, suggesting a long-term state of negative mass balance. Comparison of mean annual specific mass balances (up to -0.34 m w.e. yr-1) with surface mass balance measurements for the nearby Ward Hunt Ice Shelf suggest that basal melt is a key contributor to total ice shelf thinning. The development and expansion of new and existing surface cracks, as well as ice-marginal and epishelf lake development, indicate significant ice shelf weakening. Over the next few decades it is likely that the Milne Ice Shelf will continue to deteriorate.

This study presents the first comprehensive assessment of the Petersen Ice Shelf and the Petersen Bay epishelf lake, and examines their current characteristics and changes to their structure between 1959 and 2012. The surface of the Petersen Ice Shelf is characterized by a rolling topography of ridges and troughs, which is balanced by a rolling basal topography, with thicker ice under the surface ridges and thinner ice under the surface troughs. Based on thickness measurements collected in 2011 and area measurements from August 2012, the Petersen Ice Shelf has a surface area of 19.32 km2 and a mean thickness of 29 m, with the greatest thicknesses (>100 m) occurring at the fronts of tributary glaciers feeding into the ice shelf. The tributary glaciers along the northern coast of Petersen Bay contributed an estimated area-averaged 7.89 to 13.55 cm yr-1 of ice to the ice shelf between 2011 and 2012. This input is counteracted by a mean surface ablation of 1.30 m yr-1 between 2011 and 2012, suggesting strongly negative current mass balance conditions on the ice shelf. The Petersen Ice Shelf remained relatively stable until 2005 when the first break-up in recent history occurred, removing >8 km2 of ice shelf surface area. This break-up led to the drainage of the epishelf lake once the ice shelf separated from the southern coast, providing a conduit through which the freshwater from the lake escaped. More break-ups occurred in summers 2008, 2011 and 2012, which resulted in a >31.2 km2 loss in surface area (~63% of June 2005 area). While ephemeral regions of freshwater have occurred along the southern coast of Petersen Bay since 2005 (with areas ranging from 0.32-0.53 km2), open water events and a channel along the southern coast have prevented the epishelf lake from reforming. Based on these past and present observations it is unlikely that Petersen Ice Shelf will continue to persist long into the future.

This study presents a comprehensive overview of the current state of the Milne Ice Shelf and how it has changed over the last 59 years. The 205 ±1 km2 ice shelf experienced a 28% (82 ±0.8 km2) reduction in area between 1950 – 2009, and a 20% (2.5 ±0.9km3 water equivalent (w.e.)) reduction in volume between 1981 – 2008/2009, suggesting a long-term state of negative mass balance. Comparison of mean annual specific mass balances (up to -0.34 m w.e. yr-1) with surface mass balance measurements for the nearby Ward Hunt Ice Shelf suggest that basal melt is a key contributor to total ice shelf thinning. The development and expansion of new and existing surface cracks, as well as ice-marginal and epishelf lake development, indicate significant ice shelf weakening. Over the next few decades it is likely that the Milne Ice Shelf will continue to deteriorate.

The Lower Devonian carbonate-clastic sequence of southwest Ellesmere Island accumulated in the Franklinian Basin at approximately 15(DEGREES)N latitude. A variety of depositional settings are represented, ranging from tidal flat to basinal environments. These environments can be recognized in Lower Devonian rocks across the Arctic Islands. / Progradation of the carbonate sequence of southwest Ellesmere Island occurred in the Early Devonian, but was periodically interrupted in the Zlichovian/Dalejan by transgressive events. Upward movement in the newly named Inglefield Uplift occurred throughout the Devonian, and shed clastic sediments westward that, in Middle to Late Devonian time, finally overwhelmed the marine carbonates and resulted in fluvial deposition on southern Ellesmere Island. / Certain formations in the Lower Devonian sequence are profusely fossiliferous, in particular the Blue Fiord Formation, which contains an abundant fauna including numerous species of coral and brachiopods. Both of these groups belong to the Old World Biogeographic Realm, and indicate a Zlichovian age for the lower Blue Fiord Formation of southern Ellesmere Island.

This study presents a comprehensive overview of the current state of the Milne Ice Shelf and how it has changed over the last 59 years. The 205 ±1 km2 ice shelf experienced a 28% (82 ±0.8 km2) reduction in area between 1950 – 2009, and a 20% (2.5 ±0.9km3 water equivalent (w.e.)) reduction in volume between 1981 – 2008/2009, suggesting a long-term state of negative mass balance. Comparison of mean annual specific mass balances (up to -0.34 m w.e. yr-1) with surface mass balance measurements for the nearby Ward Hunt Ice Shelf suggest that basal melt is a key contributor to total ice shelf thinning. The development and expansion of new and existing surface cracks, as well as ice-marginal and epishelf lake development, indicate significant ice shelf weakening. Over the next few decades it is likely that the Milne Ice Shelf will continue to deteriorate.

This study presents the first comprehensive assessment of the Petersen Ice Shelf and the Petersen Bay epishelf lake, and examines their current characteristics and changes to their structure between 1959 and 2012. The surface of the Petersen Ice Shelf is characterized by a rolling topography of ridges and troughs, which is balanced by a rolling basal topography, with thicker ice under the surface ridges and thinner ice under the surface troughs. Based on thickness measurements collected in 2011 and area measurements from August 2012, the Petersen Ice Shelf has a surface area of 19.32 km2 and a mean thickness of 29 m, with the greatest thicknesses (>100 m) occurring at the fronts of tributary glaciers feeding into the ice shelf. The tributary glaciers along the northern coast of Petersen Bay contributed an estimated area-averaged 7.89 to 13.55 cm yr-1 of ice to the ice shelf between 2011 and 2012. This input is counteracted by a mean surface ablation of 1.30 m yr-1 between 2011 and 2012, suggesting strongly negative current mass balance conditions on the ice shelf. The Petersen Ice Shelf remained relatively stable until 2005 when the first break-up in recent history occurred, removing >8 km2 of ice shelf surface area. This break-up led to the drainage of the epishelf lake once the ice shelf separated from the southern coast, providing a conduit through which the freshwater from the lake escaped. More break-ups occurred in summers 2008, 2011 and 2012, which resulted in a >31.2 km2 loss in surface area (~63% of June 2005 area). While ephemeral regions of freshwater have occurred along the southern coast of Petersen Bay since 2005 (with areas ranging from 0.32-0.53 km2), open water events and a channel along the southern coast have prevented the epishelf lake from reforming. Based on these past and present observations it is unlikely that Petersen Ice Shelf will continue to persist long into the future.

This study presents a comprehensive overview of the current state of the Milne Ice Shelf and how it has changed over the last 59 years. The 205 ±1 km2 ice shelf experienced a 28% (82 ±0.8 km2) reduction in area between 1950 – 2009, and a 20% (2.5 ±0.9km3 water equivalent (w.e.)) reduction in volume between 1981 – 2008/2009, suggesting a long-term state of negative mass balance. Comparison of mean annual specific mass balances (up to -0.34 m w.e. yr-1) with surface mass balance measurements for the nearby Ward Hunt Ice Shelf suggest that basal melt is a key contributor to total ice shelf thinning. The development and expansion of new and existing surface cracks, as well as ice-marginal and epishelf lake development, indicate significant ice shelf weakening. Over the next few decades it is likely that the Milne Ice Shelf will continue to deteriorate.