Variable climatic conditions dominate recent phytoplankton dynamics in Chesapeake Bay

Details

• Journal Title:
  Scientific Reports
• Personal Author:
  Harding,, Lawrence W. ; Mallonee, Michael E. ; Perry, Elgin S. ; Miller, W. David ; Adolf, Jason E. ; Gallegos, Charles L. ; Paerl, Hans W.
• NOAA Program & Office:
  NMFS (National Marine Fisheries Service) ; NOS (National Ocean Service)
• Description:
  Variable climatic conditions strongly influence phytoplankton dynamics in estuaries globally. Our study area is Chesapeake Bay, a highly productive ecosystem providing natural resources, transportation, and recreation for nearly 16 million people inhabiting a 165,000-km(2) watershed. Since World War II, nutrient over-enrichment has led to multiple ecosystem impairments caused by increased phytoplankton biomass as chlorophyll-a (chl-a). Doubled nitrogen (N) loadings from 1945-1980 led to increased chl-a, reduced water clarity, and low dissolved oxygen (DO), while decreased N loadings from 1981-2012 suggest modest improvement. The recent 30+ years are characterized by high inter-annual variability of chl-a, coinciding with irregular dry and wet periods, complicating the detection of long-term trends. Here, we synthesize time-series data for historical and recent N loadings (TN, NO2 + NO3), chl-a, floral composition, and net primary productivity (NPP) to distinguish secular changes caused by nutrient over-enrichment from spatio-temporal variability imposed by climatic conditions. Wet years showed higher chl-a, higher diatom abundance, and increased NPP, while dry years showed lower chl-a, lower diatom abundance, and decreased NPP. Our findings support a conceptual model wherein variable climatic conditions dominate recent phytoplankton dynamics against a backdrop of nutrient over-enrichment, emphasizing the need to separate these effects to gauge progress toward improving water quality in estuaries.
• Keywords:
  Climatic Changes Ecology Phytoplankton Climatic Changes
• Source:
  Scientific Reports 6 (23773)
• DOI:
  https://doi.org/10.1038/srep23773
• Pubmed Central ID:
  PMC4824454
• Document Type:
  Journal Article
• Place as Subject:
  Chesapeake Bay (Md. and Va.)
• Rights Information:
  CC BY
• Compliance:
  PMC
• Main Document Checksum:
  urn:sha-512:b27b2e38e74de9e1444b5d603bd5cdf9bbf43065b6347645d94f1aee51a5a4284ad3dc046eb21556ead04604ea616fe348e4b278705f092392561954a2195035
• Download URL:
  https://repository.library.noaa.gov/view/noaa/24084/noaa_24084_DS1.pdf
• File Type:
  [PDF - 5.43 MB ]