Plankton Concentration in Oahu’s Commercial Harbors and the Ballast Check 2

Posted on Feb 26, 2018 in Main

DLNR DAR Ballast Water and Hull Fouling Program commenced a pilot study to (1) examine the concentration of plankton in three commercial harbors on Oahu and (2) investigate the use of a new technology, Ballast Check 2, in measuring ballast water compliance.

Hawaii Administrative Rule (HAR) §13-76-19 will be amended to apply to interisland transit. In light of this amendment, a pilot study was conducted to survey the concentration of ≥50 µm zooplankton and ≥10 µm to <50 µm phytoplankton in two commercial harbors on Oahu, the hub for AIS transfer throughout the Hawaiian Islands. From November through December 2017, water quality and plankton concentration were examined from Honolulu Harbor, Kewalo Basin, and Rainbow Harbor, representing different shipping profiles. Phytoplankton concentration was measured using the Ballast Check 2 and zooplankton were enumerated using a microscope. See  phytoplankton and zooplankton concentration for data collected.

International Maritime Organization (IMO) Guidelines D-2 Regulations for BW Management System Performance Standards specify the number of viable cells per microorganism category permitted in ballast water discharge (Table 1). Currently, the 10-50 μm size class are enumerated using epifluorescence microscopy to determine compliance. However, this method requires technically trained staff, long hours of enumeration, and expensive, bulky instrumentation and would be unfeasible to perform during routine BW compliance monitoring inspections. DLNR conducted an investigation into a new technology by Turner Designs, the Ballast Check 2 (BC2), which is purported to simplify BW discharge compliance monitoring for the 10-50 μm size class. The technology utilizes phytoplankton fluorescence as a proxy for cell viability and concentration. See further information about mechanism and theory behind the BC2. BC2 Data and results from the BC2 investigation are provided in this summary (in development).

Table 1. Summary of IMO D-2 Regulations.

Microorganism Category IMO Standards
Zooplankton >50 μm < 10 viable organisms/m3
Phytoplankton 10-50 μm < 10 viable organisms/mL
Vibro cholerae <1 colony forming units/100 mL
Escherichia coli <100 colony forming units/100 mL
Intestinal Enterococci <100 colony forming units/100 mL