Geology topics

Tom F. Fondell

Publications and source records attributed to Tom F. Fondell.

4 recordsLinked to original sources

USGS2018

Nutrient dynamics in partially drained arctic thaw lakes

Thaw lakes are ubiquitous on arctic coastal plains (ACPs). While many thaw lakes have steep banks, stable water levels, and static surface areas, others only partially fill their basins and vary in area over the summer. These partially drained lakes (PDLs) are hydrologically connected to the wetlands immediately surrounding them. Heat and nutrient availability limit aquatic productivity on ACPs, and we hypothesized that shallow shorelines and greater hydrologic connectivity with the landscape should result in greater nutrient concentrations and biogeochemical cycling in PDLs. We tested this by monitoring water chemistry in lakes with varying levels of seasonal drainage in sandy and silty peaty lowland sites on the ACP of Alaska. One highly drained lake (N1) was significantly warmer than minimally drained lakes (minDLs) related to earlier ice off, reaching temperatures as high as 16 °C in June when minDLs still contained ice. Ammonia, total dissolved phosphorus, and dissolved organic carbon and nitrogen concentrations were higher in lakes with greater drainage, and concentrations in N1 rivaled those in the small, biologically productive ponds. Many PDLs displayed a midsummer decrease in nutrients consistent with assimilation by the aquatic ecosystem, and a late‐summer increase most likely related to runoff from drained lake margins following precipitation. N1 exported kilograms of ammonium and total dissolved phosphorus to the stream network over the summer. Given increased warming and drying in the arctic, the proportion of PDLs may be changing, which in turn may affect nutrient and organic matter availability in arctic lakes and export to downstream environments.

Journal of Geophysical Research: Biogeosciences↗

USGS2014

Prevalence, transmission, and genetic diversity of blood parasites infecting tundra-nesting geese in Alaska

A total of 842 blood samples collected from five species of tundra-nesting geese in Alaska was screened for haemosporidian parasites using molecular techniques. Parasites of the genera Leucocytozoon Danilewsky, 1890, Haemoproteus Kruse, 1890, and Plasmodium Marchiafava and Celli, 1885 were detected in 169 (20%), 3 (<1%), and 0 (0%) samples, respectively. Occupancy modeling was used to estimate prevalence of Leucocytozoon parasites and assess variation relative to species, age, sex, geographic area, year, and decade. Species, age, and decade were identified as important in explaining differences in prevalence of Leucocytozoon parasites. Leucocytozoon parasites were detected in goslings sampled along the Arctic Coastal Plain using both historic and contemporary samples, which provided support for transmission in the North American Arctic. In contrast, lack of detection of Haemoproteus and Plasmodium parasites in goslings ( n = 238) provided evidence to suggest that the transmission of parasites of these genera may not occur among waterfowl using tundra habitats in Alaska, or alternatively, may only occur at low levels. Five haemosporidian genetic lineages shared among different species of geese sampled from two geographic areas were indicative of interspecies parasite transmission and supported broad parasite or vector distributions. However, identical Leucocytozoon and Haemoproteus lineages on public databases were limited to waterfowl hosts suggesting constraints in the range of parasite hosts.

Alaska↗

USGS2014

Historical and contemporary imagery to assess ecosystem change on the Arctic coastal plain of northern Alaska

The Arctic Coastal Plain of northern Alaska is a complex landscape of lakes, streams, and wetlands scattered across low-relief tundra that is underlain by permafrost. This region of the Arctic has experienced a warming trend over the past three decades leading to thawing of on-shore permafrost and the disappearance of sea ice at unprecedented rates. The U.S. Geological Survey’s (USGS) Changing Arctic Ecosystems (CAE) research initiative was developed to investigate and forecast these rapid changes in the physical environment of the Arctic, and the associated changes to wildlife populations, in order to inform key management decisions by the U.S. Department of the Interior and other agencies. Forecasting future wildlife responses to changes in the Arctic can benefit greatly from historical records that inform what changes have already occurred. Several Arctic wildlife and plant species have already responded to climatic and physical changes to the Arctic Coastal Plain of northern Alaska. Thus, we located historical aerial imagery to improve our understanding of recent habitat changes and the associated response to such changes by wildlife populations. In this report, we describe and make available a set of 61 georectified aerial images of the Arctic Coastal Plain (taken from 1948 to 2010) that were obtained by the USGS to inform research objectives of the USGS CAE Initiative. Here, we describe the origins, metadata, and public availability of these images that were obtained within four main study areas on the Arctic Coastal Plain: Teshekpuk Lake Special Area, Chipp River, the Colville River Delta, and locations along the Dalton Highway Corridor between the Brooks Range and Deadhorse. We also provide general descriptions of observable changes to the geomorphology of landscapes that are apparent by comparing historical and contemporary images. These landscape changes include altered river corridors, lake drying, coastal erosion, and new vegetation communities. All original and georectified images and metadata are available through the USGS Alaska Science Center Portal (search under ‘Project Name’ using title of this report) or by contacting ascweb@usgs.gov .

Alaska↗

USGS2012

Changing Arctic ecosystems - measuring and forecasting the response of Alaska's terrestrial ecosystem to a warming climate

The Arctic Coastal Plain of northern Alaska is a complex landscape of lakes, streams, and wetlands scattered across low relief tundra that is underlain by permafrost. This region of the Arctic has experienced a warming trend over the past three decades, leading to thawing of on-shore permafrost and the disappearance of sea ice at an unprecedented rate. The loss of sea ice has increased ocean wave action, leading to higher rates of erosion and salt water inundation of coastal habitats. Warming temperatures also have advanced the overall phenology of the region, including earlier snowmelt, lake ice thaw, and plant growth. As a result, many migratory species now arrive in the Arctic several days earlier in spring than in the 1970s. Predicted warming trends for the future will continue to alter plant growth, ice thaw, and other basic landscape processes. These changes will undoubtedly result in different responses by wildlife (fish, birds, and mammals) and the food they rely upon (plants, invertebrates, and fish). However, the type of response by different wildlife populations and their habitats-either positively or negatively-remains largely unknown.

Alaska↗