Article

 

Abandoning Sverdrup’s critical depth hypothesis on phytoplankton blooms Public Deposited

Analytics

Downloadable Content

Download PDF
https://ir.library.oregonstate.edu/concern/articles/wh246s837

Descriptions

Attribute NameValues
Creator
Abstract
  • The Critical Depth Hypothesis formalized by Sverdrup in 1953 posits that vernal phytoplankton blooms occur when surface mixing shoals to a depth shallower than a critical depth horizon defining the point where phytoplankton growth exceeds losses. This hypothesis has since served as a cornerstone in plankton ecology and reflects the very common assumption that blooms are caused by enhanced growth rates in response to improved light, temperature, and stratification conditions, not simply correlated with them. Here, a nine-year satellite record of phytoplankton biomass in the subarctic Atlantic is used to reevaluate seasonal plankton dynamics. Results show that (1) bloom initiation occurs in the winter when mixed layer depths are maximum, not in the spring, (2) coupling between phytoplankton growth (l) and losses increases during spring stratification, rather than decreases, (3) maxima in net population growth rates (r) are as likely to occur in midwinter as in spring, and (4 ) r is generally inversely related to l. These results are incompatible with the Critical Depth Hypothesis as a functional framework for understanding bloom dynamics. In its place, a ‘‘Dilution–Recoupling Hypothesis’’ is described that focuses on the balance between phytoplankton growth and grazing, and the seasonally varying physical processes influencing this balance. This revised view derives from fundamental concepts applied during field dilution experiments, builds upon earlier modeling results, and is compatible with observed phytoplankton blooms in the absence of spring mixed layer shoaling.
  • Key words: Critical Depth Hypothesis; grazing; growth rates; North Atlantic; phytoplankton blooms; remote sensing.
Resource Type
DOI
Date Available
Date Issued
Citation
  • Behrenfeld, M. J. (2010). Abandoning Sverdrup’s Critical Depth Hypothesis on phytoplankton blooms [Electronic version]. Ecology, 91(4), 977-989
Journal Title
Journal Volume
  • 91
Journal Issue/Number
  • 4
Academic Affiliation
Rights Statement
Publisher
Language
Replaces
Additional Information
  • description.provenance : Made available in DSpace on 2010-07-13T21:55:28Z (GMT). No. of bitstreams: 1 Behrenfeld.AbandoningSverdrupsCriticalDepth.pdf: 1129562 bytes, checksum: 6cc27406607771e8c2fe1a8f895d8030 (MD5) Previous issue date: 2010-04
  • description.provenance : Submitted by Sue Kunda (sue.kunda@oregonstate.edu) on 2010-07-13T20:47:41Z No. of bitstreams: 1 Behrenfeld.AbandoningSverdrupsCriticalDepth.pdf: 1129562 bytes, checksum: 6cc27406607771e8c2fe1a8f895d8030 (MD5)
  • description.provenance : Approved for entry into archive by Michael Boock(michael.boock@oregonstate.edu) on 2010-07-13T21:55:28Z (GMT) No. of bitstreams: 1 Behrenfeld.AbandoningSverdrupsCriticalDepth.pdf: 1129562 bytes, checksum: 6cc27406607771e8c2fe1a8f895d8030 (MD5)

Relationships

Parents:

This work has no parents.

Items

Thumbnail Title Date Uploaded Visibility Actions
Behrenfeld.AbandoningSverdrupsCriticalDepth.pdf 2017-07-10 Public