David Richardson’s website

Welcome to my website.  Below find posts with interesting links or explore the rest of my website to see my teaching and research interest.  I am interested in the following topics aquatic ecosystem ecology; invasive species; technology and aquatic ecosystems; biogeochemistry; lake metabolism; human impacts on streams, rivers, and lakes.

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Long-term ice phenology

Led by Dr. Sapna Sharma at York University, Ontario, we published long-term ice phenology records spanning up to 578 years for 78 lakes around the Northern Hemisphere. These phenomenal records extend before the start of the Industrial Revolution. For example, two lakes that I work with regularly and helped provide the data for are Mohonk Lake (New York) which has ice on and off records dating back to 1932 and Lake Sunapee (New Hampshire) which has ice off records dating back to 1869. Both of those records have been collected consistently in partnership with particular families that live on or near the lakes and have collected these records across generations. The Smiley family recorded the Mohonk Lake ice on and off dates in conjunction with owning and operating the Mohonk Mountain House. The Osborne family defined the ice off date on Lake Sunapee as the day first possible to navigate a boat from north end of the lake to the south end. Another example is Lake Suwa in Japan – the ice record for Lake Suwa was started in 1443 by a family of Shinto priest and has continued since then.

The data for these lakes and many others are available through our publication in the journal ‘scientific data’ here.

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Linking the stream/lake transitional zone

Here is a new paper out titled “Dynamics of the stream–lake transitional zone affect littoral lake metabolism” from a great group of Lake Sunapee collaborators led by the amazing Dr. Nicole Ward! We examined two stream inflows from Lake Sunapee, New Hampshire (see figure below) and found that stream inputs affect the metabolism of the organism’s in the lake itself. It is important to think about what is happening in the landscape as that might affect the edges of the lake and subsequently the ecosystem function at the middle of the lake at a later time period. Read the study published in the journal Aquatic Sciences here.

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Lake ice is being lost at record rates…

Lake ice is a common phenomena in lakes around the northern hemisphere particularly in temperate regions and more northern in latitude. Phenology is nature’s calendar – the seasonal timing of natural trends like when birds migrate or plants flower. Lake ice phenology can be recorded as ice-in (when lakes freeze in the winter) and ice-out (when lakes freeze in the spring). By comparing the two dates, we can calculate the ice duration or length of the ice season. Observers, both scientists and non-scientists, have been recorded lake ice phenology for centuries. For example, Shinto priests in Japan have been recording ice phenology since 1397 as part of religious observations (see this article that we wrote for the story of the Shinto practice). Locally, Mohonk Lake, New Paltz, has an ice record that predates World War 2 because the Mohonk Mountain House, built on the shore of Mohonk Lake, have used the lake for refrigeration and recreation (see picture below from the Mohonk Mountain House instagram).

We can use these long-term records of lake ice phenology as indicators of climate change and did so in a new collaborative study led by Dr. Sapna Sharma (York University, Canada), Dr. Iestyn Woolway, and myself among researchers from countries around the northern hemisphere. We re-assessed ice trends for the first time since 2004 for 60 lakes by studying ice phenology records ranging from 107 to 204 years old, spanning from prior to the Industrial Revolution. We found that lakes are losing, on average, 17 days of ice cover per century. Moreover, recently, in the past 25 years, the trends were much faster than any other previous time over the century. You can read the original paper in the Journal of Geophysical Research Biogeosciences here.

Figure from Sharma et al. (2021) showing rapidly changing ice-on and ice-off dates in lakes across the northern hemisphere.
Frozen Lake Sunapee, one of the lakes from the study. Photo credit: Midge Eliassen

The alarming trend of ice loss will ultimately decrease water quality, increase water loss, and harm economic, cultural, and recreational benefits that we enjoy from frozen lakes. A reduction in greenhouse gas emissions to curb climate change and minimize air temperature increases will be the primary way to mitigate ice loss.

The paper also received some press in popular media including an article in the Washington Post. We also wrote a short article in The Conversation about our study. Please peruse the links below for more details.

  1. Washington Post. Earth’s lakes are warming at a feverish pace, with the Great Lakes leading the way. https://www.washingtonpost.com/weather/2021/11/04/great-lakes-fastest-warming-study/
  2. The Weather Channel: https://weather.com/news/climate/video/lakes-in-northern-hemisphere-warming-alarmingly-fast
  3. The Toronto Star. Barrie’s Kempenfelt Bay has lost nearly a month of ice cover since 1852, new York University led study shows.  https://www.thestar.com/local-barrie/news/2021/10/31/barrie-s-kempenfelt-bay-has-lost-nearly-a-month-of-ice-cover-since-1852-new-york-university-led-study-shows.html
  4. Simcoe.com.  Barrie’s Kempenfelt Bay has lost nearly a month of ice cover since 1852, new York University led study shows.  https://www.simcoe.com/news-story/10502121-barrie-s-kempenfelt-bay-has-lost-nearly-a-month-of-ice-cover-since-1852-new-york-university-led-study-shows/
  5. Helsingin Sanomat.  https://www.hs.fi/tiede/art-2000008356794.html
  6. CTV News. Ice loss, toxic algal blooms: Canadian study looks at Northern Hemisphere warming lakes.  https://www.ctvnews.ca/climate-and-environment/ice-loss-toxic-algae-blooms-canadian-study-looks-at-northern-hemisphere-s-warming-lakes-1.5635570
  7. CBC Radio. Up North with Jonathan Pinto. https://www.cbc.ca/listen/live-radio/1-84-up-north/clip/15873926-rapidly-warming-northern-lakes
  8. CBC News. Northern lakes losing ice coverage due to climate change.  https://www.cbc.ca/news/canada/sudbury/northern-lakes-ice-coverage-climate-change-1.6221787
  9. YFile. Northern lakes warming six times faster in the past 25 years. https://yfile.news.yorku.ca/2021/10/24/northern-lakes-warming-six-times-faster-in-the-past-25-years/
  10. Digital Journal. Study finds Northern Hemisphere lakes losing ice coverage due to climate change. https://www.digitaljournal.com/tech-science/study-finds-northern-hemisphere-lakes-losing-ice-coverage-due-to-climate-change/article
  11. Science Daily. Northern lakes warming six times faster in the past 25 years. https://www.sciencedaily.com/releases/2021/10/211021121002.htm
  12. Earth.com. Northern lakes are warming at an alarming rate. https://www.earth.com/news/northern-lakes-are-warming-at-an-alarming-rate/

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Mohonk Lake is getting warmer…

I am pleased to share a new study that I worked on with Dr. Bella Oleksy (Cary Institute, @isabella_oleksy). We examined a 35-yr temperature record of Mohonk Lake and found lake stratification is getting longer + stronger, and responding to global climate trends. The paper was published in the American Geophysical Unions Geophysical Research Letters and can be found here. Here is an overview of the study and in interview with Dr. Oleksy: https://caryinstitute.org/news-insights/feature/mohonk-lake-getting-warmer-and-more-stagnant-climate-change?utm_source=Twitter…

This study was based on long-term data from @mohonkpreserve. We developed a new metric we call “mixing action” that accounts for an entire season of lake stratification including onset and mixing timing and peak stability of stratification. What drove higher mixing actions each year? In Mohonk Lake, there have been longer stratified seasons, earlier onset of stratification in the spring, and stronger water column stability. Here is a cool visualization of these trends:


Many lakes to long-term collectors of data including Dan Smiley, Paul Huth, John Thompson, Natalie Feldsine, Climate Tracker volunteers, interns, Mohonk Mountain House, and Mohonk Preserve. This is a particularly exciting paper for me because Bella was an NSF REU for SUNY New Paltz way back when I was first starting as a professor. It has been amazing to have her return to the area as a post doctoral scientist at the Cary Institute of Ecosystem studies and to work with her again on a new project!

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Lake habitats are disappearing as the climate changes

I am excited to share our new paper in Nature Climate Change led by @benmkraemer along w/ @rmpilla and other international collaborators. The paper (https://nature.com/articles/s41558-021-01060-3?fbclid…) details the shifts in thermal habitats (temps needed by species to survive) occurring with climate change.

Here is a mini-lecture about the project from the lead author, Dr. Ben Kraemer: https://t.co/ouJRaRpKfT?amp=1

Species will need to move either in space or in seasonal time to survive as the thermal distributions change. Here is an animated figure from the paper (credit: @benmkraemer) that shows the shifting thermal habitat.

Here is a distribution of the lakes in the study:

Here is a @NatureClimate News & Views the article about lake thermal habitats and climate change! The paper explains some of the key findings in the paper and has some additional graphics: https://t.co/ga7ynOYZkB?amp=1

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Lake metabolism under the ice

Our new peer-reviewed paper is out in the journal Inland Waters, the flagship journal for the International Society of Limnology. Lakes have historically been considered dormant during the winter when the top of many northern hemisphere lakes freeze over. We had a unique full year record of water chemistry and physics from Lake Sunapee in New Hampshire. We estimated lake metabolism (respiration and photosynthesis) from throughout the entire year. Despite the lake being close to freezing and darker in the winter, organisms under the ice continued to respire at rates higher than during the summer and photosynthesis continued throughout the winter. We provided evidence that year-round sampling is essential for understanding carbon cycling in lakes in our region.

This paper was a collaborative effort with researchers from Dartmouth College, Virginia Tech, Colby College, and Cary Institute of Ecosystem Studies and was led by Dr. Jennifer Brentrup, currently at St. Olaf College in Minnesota, myself, Dr. Cayelan Carey and Nicole Ward, MS both from Virginia Tech.

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Global trends in lake thermal structure

Our new peer-reviewed paper is out in the journal Scientific Reports published by Nature Research. We collected data from lakes around the world to see how they have changed in their water temperatures over a 40-year period (1970-2009). The surface waters of global lakes is warming quickly. However, deep water in our study lakes were changing much more variably with some lakes having cooling deep water and some lakes having warming deep water.

This was a large co-authored paper with many participants from around the world including Africa, Asia, Australia, Europe, and North America. The project stemmed from efforts through the Global Lakes Ecological Observatory Network (GLEON). The project was led by Rachel Pilla, a graduate student from University of Miami Ohio.

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Lake Sunapee data available

We published Lake Sunapee buoy data used for several of our papers (Bruesewitz et al. 2015; Richardson et al. 2016) in an open online data repository called the Environmental Data Initiative. See here, https://doi.org/10.6073/pasta/846a36bf6fd704e508511e5f8a2ab3b5, for meteorological and water sensor data from 2007-2013 on the Lake Sunapee Protective Association‘s water quality buoy. This was one of the earlier Global Lake Ecological Observatory Network‘s buoys (GLEON) and one of the best places to visit!

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Nutrient limitation in lakes across northeastern United States

Our new peer-reviewed paper is out in the journal Inland Waters. We studied how nitrogen and phosphorus can limit phytoplankton growth in freshwater lakes. We performed identical experiments in 16 lakes across northeastern United States; we found that phytoplankton communities were limited by nitrogen in some lakes, phosphorus in others, and both in more. The limitation was related to land-use and lake characteristics.

This was a large co-authored paper with many participants including professors and students across 12 institutions. The project stemmed from our annual northeastern Global Lakes Ecological Observatory Network (GLEON) meeting where we co-developed the project and experimental design. The study was led by an amazing group of undergraduates, Abby Lewis (Pomona College ’19), Brian Kim (Colby College ’18), Hailee Edwards (SUNY New Paltz ’18), and Heather Wander (SUNY New Paltz ’18) along with Denise Brueswitz (Professor at Colby College) and myself. Our group worked incredibly hard on the data analysis, writing, and coordinating a large collaborative group.

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Serial introductions modify a trophic cascade in Lake Minnewaska – a new paper

Our new peer-reviewed paper is in the September issue of the journal Freshwater Science. We have been studying Lake Minnewaska for many years now and found successive (serial) introductions of two fish species – first a minnow (Golden shiner) followed by Largemouth bass. We discovered that the bass ate all the minnows and following the loss of all minnows from the lake, the lake partially returned to pre-fish conditions including high water clarity.

My co-authors are all undergraduates from SUNY New Paltz from a variety of majors (Biology, Biochemistry, and Environmental Geochemical Sciences) who have gone on different career paths. All co-authors were incredibly involved in the process. We met for 2+ years in multiple research classes working through data collection, data analysis, writing, etc…; most of the students spent summers as paid researchers via various programs and grants. They devoted a ton of time and effort, even post graduation to seeing this paper get published. Hopefully, this process was informative and helped them develop useful skills for their future careers. (Thanks Emma, Hailee, Dejea, Avery, Sawyer, Kayla, and Heather!)


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