Vanessa L. Lougheed

Disappearing Arctic tundra ponds: Fine‐scale analysis of surface hydrology in drained thaw lake basins over a 65 year period (1948–2013)

Long-term fine-scale dynamics of surface hydrology in Arctic tundra ponds (less than 1 ha) are largely unknown; however, these small water bodies may contribute substantially to carbon fluxes, energy balance, and biodiversity in the Arctic system. Change in pond area and abundance across the upper Barrow Peninsula, Alaska, was assessed by comparing historic aerial imagery (1948) and modern submeter resolution satellite imagery (2002, 2008, and 2010). This was complemented by photogrammetric analysis of low-altitude kite-borne imagery in combination with field observations (2010–2013) of pond water and thaw depth transects in seven ponds of the International Biological Program historic research site. Over 2800 ponds in 22 drained thaw lake basins (DTLB) with different geological ages were analyzed. We observed a net decrease of 30.3% in area and 17.1% in number of ponds over the 62 year period. The inclusion of field observations of pond areas in 1972 from a historic research site confirms the linear downward trend in area. Pond area and number were dependent on the age of DTLB; however, changes through time were independent of DTLB age, with potential long-term implications for the hypothesized geomorphologic landscape succession of the thaw lake cycle. These losses were coincident with increases in air temperature, active layer, and density and cover of aquatic emergent plants in ponds. Increased evaporation due to warmer and longer summers, permafrost degradation, and transpiration from encroaching aquatic emergent macrophytes are likely the factors contributing to the decline in surface area and number of ponds.

USING NON-LINEAR RESPONSES OF MULTIPLE TAXONOMIC GROUPS TO ESTABLISH CRITERIA INDICATIVE OF WETLAND BIOLOGICAL CONDITION

Establishing criteria for protecting or improving wetland condition has often focused on physical and chemical factors, which can paint an incomplete picture of wetland quality. To protect the biological integrity of aquatic environments, identifying criteria based on biological responses to pollution is essential. We hypothesize that assessment of multiple taxonomic groups and response thresholds will provide statistically defensible effects-based methods to define reference condition and establish biological criteria. We used regression tree analysis to identify non-linear biological responses of three taxonomic groups (macrophytes, epiphytic diatoms, and plant-associated Zooplankton) collected from 36 depressional wetlands in the Muskegon River watershed (Michigan, USA). Multi-metric biotic indices were developed for all three taxonomic groups and these indices were combined to reveal biologically relevant thresholds along a gradient of human disturbance. We found these three taxonomic groups responded at similar levels of impairment and could be used to classify wetlands into three groups: reference sites representing the highest quality wetlands in the landscape; slightly altered sites where the most sensitive organisms responded (sensitive plants, diatoms); and degraded sites where extensive changes in community structure occurred, which may reflect a shift to an alternate state. For the Muskegon River watershed, in particular, this analysis allowed us to identify sites in need of restoration, including approximately one-third of the depressional wetlands in the watershed. This study outlines a method for identifying criteria that could be used for regulatory purposes. In particular, we recommend the use of community-level metrics in identifying broad-based changes in community composition that may represent shifts to alternate states, as well as the use of sensitive indicators, such as the occurrence of sensitive plant and diatom taxa.

Influences of Multi-Scale Habitat on Metabolism in a Coastal Great Lakes Watershed

Spatial heterogeneity influences ecosystem structure and function across multiple habitat scales. Although primary production and respiration are fundamental to energy cycling in aquatic ecosystems, we know relatively little about how habitat scale influences metabolism. In this study, we adopted a multi-scale habitat approach to evaluate primary production and respiration in a coastal Great Lakes watershed that is experiencing pressure from past, present, and anticipated future human activities. We divided the watershed into five macrohabitats (stream, river, wetland, drowned-river mouth lake, and Great Lake), two mesohabitats (benthic and water column), and four microhabitats (periphytic substrates: sand/sediment, rock, wood, and plant) for evaluation of spatial patterns and synchrony in metabolism. Factors that influenced patterns of metabolism were scale dependent. Algal biomass strongly influenced spatial patterns in metabolism at the meso- and microhabitat scales; greater algal biomass translated to higher areal-specific and lower chlorophyll-specific metabolism at benthic mesohabitat and sand/sediment and rock microhabitats. Benthic metabolism overwhelmed water column metabolism, irrespective of location or time of year. Watershed position was important at the macrohabitat scale, with greater overall metabolism in macrohabitats located lower in the watershed. Average synchrony in metabolism rates was greatest at the macrohabitat scale, suggesting metabolic patterns that are evident at finer scales may become integrated at coarser scales. Our results (1) show that spatial and temporal patterns in metabolism are shaped by factors that are dependent upon habitat scale; (2) highlight the importance of benthic productivity across habitat and season; and (3) suggest that hydrologic connectivity strongly influences ecosystem processes, although physical factors can affect these responses as evidenced by the low levels of synchrony between Lake Michigan and the other macrohabitats.

The potential to improve water quality in the middle Rio Grande through effective wetland restoration

The Rio Grande, which forms the United States-Mexico border for much of its course, receives diverse pollutants from both urban and agricultural areas, most notably in the sister cities of El Paso (TX, USA)-Ciudad Juárez (CHI, Mexico). This study aimed to describe regional trends in water quality in waters near the El Paso-Ciudad Juárez metroplex and to examine the potential for water quality improvement through the use of a created wetland. Very few differences in nutrient chemistry were found among drains, canals and the Rio Grande, with the exception of elevated chloride and lower phosphorus levels found in the drains. Overall, chloride concentrations increased with distance downstream, likely due to concentration of salts via evaporation from irrigated agriculture. A wastewater treatment plant (WWTP) contributed substantially to total phosphorus and nitrate levels, which, together with ammonia, tended to exceed state criteria for water quality downstream of the WWTP outflow. The created Rio Bosque wetlands reduced nitrate concentrations in the water, possibly via denitrification enhanced by algae; algae increased in biomass as water flowed through the wetlands. However, the diversion of water for irrigated agriculture, resulting in the absence of water, and thus aquatic plants, in the wetland in the summer has limited the ability of this wetland to improve regional water quality.

CUREcasts: An Innovative Mechanism to Increase Communication of Scientific Outcomes to Novice and Expert Audiences within the Context of Course-Based Undergraduate Research Experiences †

The recent advent of course-based undergraduate research experiences (CUREs) has provided a unique platform for immersing students in the process of scientific discovery. Inherent of this process and of the CURE paradigm is the expectation that the data obtained from such investigations have broader applications beyond the boundaries of the classroom. However, few studies have explored the mechanisms for dissemination of CURE student-generated results aside from in-class poster and/or oral presentations. In this article, we describe the creation of CUREcasts, which harness the power of video podcast media to effectively and succinctly capture the types of research upper-level Arctic/Polar science CURE students are engaged in and the methodologies used to conduct their investigations. We likewise illustrate how the EdPuzzle platform can be used to create educational tools for instructors and scientists alike. Lastly, Student Perceptions of Learning Gains (SPLG) data are presented to demonstrate the effectiveness of the CUREcast initiative in enhancing CURE student knowledge and affect in the domain.