Characteristics of global port phytoplankton and implications for current ballast water regulations

The International Maritime Organization and U.S. Coast Guard have implemented regulations to reduce introductions of non-indigenous species via ballast water (BW). For phytoplankton, regulations limit discharges to <10 live/viable cells mL−¹ (size: 10–50 μm), ignoring other size fractions. Additionally, challenge conditions of 100 (shipboard) and 1000 (land-based) cells mL−¹ are required in BW management system certification testing. How these requirements correspond to natural phytoplankton populations is poorly resolved. The authors analyzed phytoplankton samples from 31 major ports to evaluate: a) how natural communities compare to challenge requirements and b) abundances of unregulated size fractions (i.e., <10 and ≥50 μm). None of the ports met land-based challenge conditions, and only 32% met requirements for shipboard testing. Approximately 71% of organisms ≥50 μm were centric diatoms, also unregulated by current protocols. This study demonstrates that current regulations do not consider natural phytoplankton populations, limiting control efforts for potentially harmful non-indigenous species.


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  • Accession Number: 01742776
  • Record Type: Publication
  • Files: TRIS
  • Created Date: May 17 2020 3:04PM