3.4.1 Macroalgae: Ulva lactuca brown spots

Figure 14 Ulva lactuca and the brown epiphytic algae Myrionema.

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Composite of 4 Microalga. Going clockwise from top left shows healthy Ulva (bright green), showing green frond with brown spots as a sign of infection, then two microscopic images showing brown discoloration.

Figure 14 Ulva lactuca and the brown epiphytic algae Myrionema.

Ulva (1) is the main green macroalgae used for human food. It is harvested worldwide and is being cultured in many parts of the world in pilot commercial systems. Research into wild populations has found the epipthytic brown algal genus Myrionema (2,3,4) to be widely present in Ulva wild populations. It causes Brown spots (2) and blades can be highly infested. The reduction of growth rates due to nutrient competition, and a decreased market value of the final product are a concern for commercial producers.