AsianScientist (Jul. 8, 2016) – Very much like people, seaweeds can also get sick when placed under stressful conditions. At high water temperatures, seaweeds become susceptible to a bleaching disease by a variety of normally harmless bacteria, according to new research from the University of New South Wales (UNSW) in Australia. The study was published in Environmental Microbiology.
Seaweeds are the ‘trees’ of the ocean, providing food, shelter and a vital habitat for many species of fish and other coastal marine organisms, such as crayfish and abalone.
The researchers collected samples of healthy and diseased red alga, Delisea pulchra, from about eight meters under the water at different locations on the Sydney coastline. The diseased seaweeds had undergone natural bleaching, in which areas of pigment are lost.
“A lot of attention has been paid to coral bleaching, but seaweeds are also affected by temperature-related diseases,” said senior author Dr. Suhelen Egan from the UNSW Center of Marine Bio-Innovation.
“Bleaching reduces the ability of the seaweed to photosynthesize and harvest energy from the sun, and to reproduce. It also makes them more susceptible to grazing by fish and other herbivores in the ocean.”
The researchers were surprised to identify three very different kinds of bacteria which are usually present in low numbers on seaweeds, but which are now known to cause the same bleaching disease.
“We believe these kinds of opportunistic pathogens are more common in marine environment than had been realized before,” said Egan.
The three newly identified pathogens that cause the bleaching disease are members of the Alteromonas, Aquimarina and Agarivorans genera.
The article can be found at: Kumar et al. (2016) Multiple Opportunistic Pathogens can Cause Bleaching Disease of the Red Seaweed Delisea Pulchra.
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Source: University of New South Wales.
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