A new approach for the estimation of phytoplankton cell counts associated with algal blooms

Majid Nazeer, Man Sing Wong, Janet Elizabeth Nichol

Research output: Journal article publicationJournal articleAcademic researchpeer-review

32 Citations (Scopus)


This study proposes a method for estimating phytoplankton cell counts associated with an algal bloom, using satellite images coincident with in situ and meteorological parameters. Satellite images from Landsat Thematic Mapper (TM), Enhanced Thematic Mapper Plus (ETM +), Operational Land Imager (OLI) and HJ-1 A/B Charge Couple Device (CCD) sensors were integrated with the meteorological observations to provide an estimate of phytoplankton cell counts. All images were atmospherically corrected using the Second Simulation of the Satellite Signal in the Solar Spectrum (6S) atmospheric correction method with a possible error of 1.2%, 2.6%, 1.4% and 2.3% for blue (450–520 nm), green (520–600 nm), red (630–690 nm) and near infrared (NIR 760–900 nm) wavelengths, respectively. Results showed that the developed Artificial Neural Network (ANN) model yields a correlation coefficient (R) of 0.95 with the in situ validation data with Sum of Squared Error (SSE) of 0.34 cell/ml, Mean Relative Error (MRE) of 0.154 cells/ml and a bias of − 504.87. The integration of the meteorological parameters with remote sensing observations provided a promising estimation of the algal scum as compared to previous studies. The applicability of the ANN model was tested over Hong Kong as well as over Lake Kasumigaura, Japan and Lake Okeechobee, Florida USA, where algal blooms were also reported. Further, a 40-year (1975–2014) red tide occurrence map was developed and revealed that the eastern and southern waters of Hong Kong are more vulnerable to red tides. Over the 40 years, 66% of red tide incidents were associated with the Dinoflagellates group, while the remainder were associated with the Diatom group (14%) and several other minor groups (20%). The developed technology can be applied to other similar environments in an efficient and cost-saving manner.
Original languageEnglish
Pages (from-to)125-138
Number of pages14
JournalScience of the Total Environment
Publication statusPublished - 15 Jul 2017


  • Coastal water
  • Harmful algal blooms
  • Phytoplankton cells
  • Red tides
  • Remote sensing

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution


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