The Great Hawaii Molasses Spill

On Friday November 13, Dr. Robert Bidigare of the University of Hawaii gave a seminar to the Louisiana State University Department of Oceanography and Coastal Sciences. In what was one of the most unusual talks I have ever attended, Dr. Bidigare informed a rapt audience about one of the strangest disasters to hit Hawaii: a record breaking molasses spill in Honolulu Harbor.


On September 9th, 2013, nearly 235,000 gallons of blackstrap molasses spilled out of a leaky pipe into Honolulu Harbor. Matson Navigation Company, who was transporting the molasses from a storage facility to a tanker ship in the harbor, owned the pipe. Initial reports described brown water and dead fish in the vicinity of Pier 51. The Coast Guard was called around 7:45 AM but did not discover the source of the leak until 2:30 PM. The leak was plugged by the following morning.


Molasses is often added to cattle feed on industrial farms. Photo credit: Tractorboy60, Wikipedia Commons 

Dr. Bidigare’s team sampled the area two days after the spill had occurred. They took water and substrate samples from various areas of harbor, including at the source of the spill and within the plume of spilled molasses. Unlike oil, which floats at the surface, molasses is very dense and sinks to the bottom. This made it easy for divers to collect samples for research.


Results showed that due to the huge influx of sugar in the harbor, microbial growth exploded in a very short amount of time. As these microbes broke down the molasses, they used up the available oxygen in the water, resulting in dangerously low oxygen conditions. Genetic analysis showed that the population of microbes also completely changed during the course of the spill, shifting from copiotrophs (organisms that thrive in high nutrient environments such as sewage pipes) to oligotrophs (organisms that thrive in low nutrient environments).


By the time it was over, this accident killed over 26,000 fish, smothered corals in the harbor with viscous molasses, and suffocated countless invertebrates. Most likely causes of the excessive deaths include low oxygen concentrations and osmotic shock resulting from high sucrose concentrations.


Honolulu Harbor, Hawaii where the spill took place. Photo credit: Shawn Rossi, Wikipedia Commons

Ultimately, the spill resulted in little long-term damage to Honolulu Harbor. Tidal flushing and natural decomposition of the molasses returned the environment back to natural conditions in approximately 10 days. Matson Navigation Company was fined $1,000,000 for violating the Clean Water Act and another $15,400,000 in a civil suit. As a stipulation of the civil suit, they were also forced to abandon their molasses manufacture and transport in Hawaii.


The full talk can be seen here:


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