Earlier winter/spring runoff and snowmelt during warmer winters lead to lower summer chlorophyll-a in north temperate lakes

Allison R. Hrycik, Peter D.F. Isles, Rita Adrian, Matthew Albright, Linda C. Bacon, Stella A. Berger, Ruchi Bhattacharya, Hans Peter Grossart, Josef Hejzlar, Amy Lee Hetherington, Lesley B. Knoll, Alo Laas, Cory P. McDonald, Kellie Merrell, Jens C. Nejstgaard, Kirsten Nelson, Peeter Nõges, Andrew M. Paterson, Rachel M. Pilla, Dale M. RobertsonLars G. Rudstam, James A. Rusak, Steven Sadro, Eugene A. Silow, Jason D. Stockwell, Huaxia Yao, Kiyoko Yokota, Donald C. Pierson

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


Winter conditions, such as ice cover and snow accumulation, are changing rapidly at northern latitudes and can have important implications for lake processes. For example, snowmelt in the watershed—a defining feature of lake hydrology because it delivers a large portion of annual nutrient inputs—is becoming earlier. Consequently, earlier and a shorter duration of snowmelt are expected to affect annual phytoplankton biomass. To test this hypothesis, we developed an index of runoff timing based on the date when 50% of cumulative runoff between January 1 and May 31 had occurred. The runoff index was computed using stream discharge for inflows, outflows, or for flows from nearby streams for 41 lakes in Europe and North America. The runoff index was then compared with summer chlorophyll-a (Chl-a) concentration (a proxy for phytoplankton biomass) across 5–53 years for each lake. Earlier runoff generally corresponded to lower summer Chl-a. Furthermore, years with earlier runoff also had lower winter/spring runoff magnitude, more protracted runoff, and earlier ice-out. We examined several lake characteristics that may regulate the strength of the relationship between runoff timing and summer Chl-a concentrations; however, our tested covariates had little effect on the relationship. Date of ice-out was not clearly related to summer Chl-a concentrations. Our results indicate that ongoing changes in winter conditions may have important consequences for summer phytoplankton biomass and production.

Original languageEnglish (US)
Pages (from-to)4615-4629
Number of pages15
JournalGlobal change biology
Issue number19
StatePublished - Oct 2021

Bibliographical note

Funding Information:
This study was facilitated by the Global Lake Ecological Observatory Network. We thank numerous technicians and institutions for data collection. We are also grateful to Richard Kiesling and two anonymous reviewers who greatly improved this manuscript. ARH was supported by the Vermont Space Grant Consortium under NASA Cooperative Agreement NNX15AP86H and a NASA Earth and Space Science Fellowship under NASA Cooperative Agreement 80NSSC18K1394 P0000. Data collection at Lake Erken was supported by the Swedish Infrastructure for Ecosystem Science (SITES), and DCP acknowledges support via the MANTEL (H2020‐MSCA‐ITN‐2061). RA and H‐PG also acknowledge support via the MANTEL (H2020‐MSCA‐ITN‐2061) and Limnoscenes (Biodiversa, Belmond Forum and the German Science Foundation) project. EAS acknowledges grants of RSCF project # 18‐44‐06201, of Ministry of Higher Education and Research (projects No. FZZE‐2020‐0026; No. FZZE‐2020‐0023), and of Foundation for support of applied ecological studies of Lake Baikal ( https://baikalfoundation.ru/project/tochka‐1/ ). JH acknowledges support via the ERDF/ESF project Biomanipulation (No. CZ.02.1.01/0.0/0.0/16_025/0007417). AL was supported by the Estonian Research Council grant (PUT PSG32) and by MANTEL ITN (H2020‐MSCA‐ITN‐2061). PN acknowledges Estonian Research Council grants PRG705. We acknowledge data collection by several technicians and institutions, including C. McConnell and T. Field (HY), staff and students at DESC who were involved with sample collection and analysis (AMP, JAR, HY), New York State Department of Environmental Conservation (LGR), SUNY Oneonta Biological Field Station (KY), New Hampshire Department of Environmental Services (KN), North Temperate Lakes Long Term Ecological Research site (NSF DEB‐1440297) (CPM), Delavan Lake Sanitary District and Green Lake Sanitary District (DMR), Minnesota DNR Sentinel Lakes Program (LBK), and Vermont DEC (KM).

Publisher Copyright:
© 2021 John Wiley & Sons Ltd.


  • chlorophyll-a
  • climate change
  • long-term data
  • phytoplankton biomass
  • snowmelt
  • stream discharge

PubMed: MeSH publication types

  • Journal Article


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