skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.


Title: Cascade Project at North Temperate Lakes LTER High Frequency Sonde Data from Spatial Dynamics Experiment 2018 - 2019
High-frequency continuous data for temperature, dissolved oxygen, pH, chlorophyll-a, and phycocyanin in Paul Peter lakes from mid-May to early September for the years 2018 and 2019. Inorganic nitrogen and phosphorus were added to Peter in 2019, while Paul Lake was an unfertilized reference.  more » « less
Award ID(s):
2025982
PAR ID:
10667222
Author(s) / Creator(s):
; ; ; ; ;
Publisher / Repository:
Environmental Data Initiative
Date Published:
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. Summer temperature chain data were collected from three lakes (Peter, Paul, and Tuesday) using NexSens temperature thermistors. Data are available for five years: 2013–2015 and 2018–2019. Peter and Paul Lakes have complete records for all five years, while Tuesday Lake has data for three years. During 2013–2015, thermistors recorded temperatures at depths of 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, and 5.0 meters. Beginning in 2018, thermistors were added at 4.5 and 6.0 meters. 
    more » « less
  2. {"Abstract":["Temperature and chlorophyll data were collated from multiple datasets to identify the effects of aquatic heatwaves on phytoplankton in three north temperate lakes, Peter Lake, Paul Lake, and Tuesday Lake between 2008 and 2019. Heatwaves were identified using a water temperature model constructed from temperature data from Sparkling Lake and Woodruff Airport between 1989 and 2022. Heatwave characteristics, water color, nutrients, grazing, and lake stability data are included to relate chlorophyll response to heatwaves to other conditions associated with a set of whole-lake experiments. The food web of Peter Lake was manipulated with largemouth bass additions between 2008 and 2011. Nutrient additions were made to Peter Lake and Tuesday Lake between 2013 and 2015, and again in Peter Lake in 2019. Paul Lake was always maintained as an unmanipulated reference lake. Full descriptions of the experiments can be found in Szydlowski et al., "Aquatic heatwaves increase surface chlorophyll concentrations in experimental and reference lakes.""]} 
    more » « less
  3. null (Ed.)
    Resilience was compared for alternate states of phytoplankton pigment concentration in two multiyear whole-lake experiments designed to shift the manipulated ecosystem between alternate states. Mean exit time, the average time between threshold crossings, was calculated from automated measurements every 5 min during summer stratification. Alternate states were clearly identified, and equilibria showed narrow variation in bootstrap analysis of uncertainty. Mean exit times ranged from 13 to 290 h. In the reference ecosystem, Paul Lake, mean exit time of the low-pigment state was about 100 h longer than mean exit time of the high-pigment state. In the manipulated ecosystem, Peter Lake, mean exit time of the high-pigment state exceeded that of the low-pigment state by 30 h in the cascade experiment. In the enrichment experiment mean exit time of the low-pigment state was longer than that of the high-pigment state by about 100 h. Mean exit time is a useful measure of resilience for stochastic ecosystems where high-frequency measurements are made by consistent methods over the full range of ecosystem states. 
    more » « less
  4. null (Ed.)
    ABSTRACT Seismic rays traveling just below the Moho provide insights into the thermal and compositional properties of the upper mantle and can be detected as Pn phases from regional earthquakes. Such phases are routinely identified in the continents, but in the oceans, detection of Pn phases is limited by a lack of long-term instrument deployments. We present estimates of upper-mantle velocity in the equatorial Atlantic Ocean from Pn arrivals beneath, and flanking, the Mid-Atlantic Ridge and across several transform faults. We analyzed waveforms from 50 earthquakes with magnitude Mw>3.5, recorded over 12 months in 2012–2013 by five autonomous hydrophones and a broadband seismograph located on the St. Peter and St. Paul archipelago. The resulting catalog of 152 ray paths allows us to resolve spatial variations in upper-mantle velocities, which are consistent with estimates from nearby wide-angle seismic experiments. We find relatively high velocities near the St. Paul transform system (∼8.4  km s−1), compared with lower ridge-parallel velocities (∼7.7  km s−1). Hence, this method is able to resolve ridge-transform scale velocity variations. Ray paths in the lithosphere younger than 10 Ma have mean velocities of 7.9±0.5  km s−1, which is slightly lower than those sampled in the lithosphere older than 20 Ma (8.1  km±0.3  s−1). There is no apparent systematic relationship between velocity and ray azimuth, which could be due to a thickened lithosphere or complex mantle upwelling, although uncertainties in our velocity estimates may obscure such patterns. We also do not find any correlation between Pn velocity and shear-wave speeds from the global SL2013sv model at depths <150  km. Our results demonstrate that data from long-term deployments of autonomous hydrophones can be used to obtain rare and insightful estimates of uppermost mantle velocities over hundreds of kilometers in otherwise inaccessible parts of the deep oceans. 
    more » « less
  5. This research paper describes an autoethnographic study of three individuals: Julie, a tenured faculty member and experienced engineering education researcher, and two novice engineering education researchers, Paul, a more junior faculty member, and Deepthi, a graduate student. The tripartite mentoring relationship between us formed as part of a National Science Foundation Research Initiation in Engineering Formation (NSF RIEF) project. We grounded our work in the cognitive apprenticeship model of mentoring and theory of social capital, asking the question: How do mentors and mentees perceive shared experiences? Over the course of 16 months, we collected data in the form of reflective journal entries and transcripts from individual and joint interviews, combining these with other documentation such as emails and text messages. We analyzed these data by identifying three critical incidents over the course of the relationship to date and comparing each of our perceptions of these shared experiences. We found that our perceptions of the shared experiences differed greatly, providing multiple opportunities to improve our future communication. We also discovered that our initial mentoring model in which Julie mentored Paul and Paul mentored Deepthi did not withstand scrutiny. Because Paul was new to engineering education research, it was better for Julie to mentor both Paul and Deepthi than to expect Paul to teach Deepthi topics and methods that were new to him. We assert that other projects would benefit by this approach as well. Our findings offer broad implications for the efficacy of reflection and communication in mentoring relationships. 
    more » « less