The Mystery of the Fuzz

Mystery fuzz floating at the surface of the pond. The small gas bubbles may be produced by photosynthesis.

Over the surface of the sediment in the pond, there is a fuzzy layer of what appears to be brown algae. It gathers around patches of macroalgae, is soft to the touch, and sometimes floats to the surface in patches (see the above picture), especially at night. According to some of the graduate students in Oceanography, who have been working in the pond for years already, this fuzz showed up about a year and a half ago. We have speculated for a while as to what it might be (filamentous brown alga? Cyanobacteria? Other bacteria?) and finally looked at it under a scope today. It is a thick sludge of diatoms, held together in places by soft lumps of marine snow. The diatoms are pink in this picture because I took the picture under a fluorescent light (normally they’re green or brown). The marine snow is that hazy, greenish stuff (it’s grey under normal light).

A quick note about diatoms: they’re algae, members of the division Ochrophyta, and are usually unicellular. The cells have a silica casing, known as a valve or frustule. Pennate diatoms like the ones we found here are long and slender as opposed to centric or “hat-box” shaped, and have a central groove called a raphe. Identification of diatoms almost always requires examination of the frustule, cleaned of organic matter, under Transmission Electron Microscopy (TEM). Since I haven’t done this yet, I haven’t identified these diatoms, but pennate diatoms are often found in areas with some freshwater input, which may explain their presence in the fishpond.

Microalgae at the sediment-water interface are important because many of the fish raised for food (awa, aholehole, moi) eat them. In most papers this combination of diatoms, cyanobacteria, and filamentous algae is just called microphytobenthos, or MPB.

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  • Mahalo Nui Loa

    I recently graduated from the Donahue Lab at the University of Hawai'i at Manoa and am currently a graduate student at the University of Washington. This research is funded by a Graduate Research Fellowship from the National Science Foundation, as well a scholarship from the Seattle chapter of the Achievement Rewards for College Scientists (ARCS) Foundation.
  • “Where do ecological ideas come from? …Most do not spring deductively from the minds of ecologists, like Athena from the head of Zeus. Instead, they emerge when ecologists absorb the essential spirit of individual places– their genius loci.”

    ~Mary V. Price & Ian Billick, "The Ecology of Place"
  • “Aloha is the intelligence with which we meet life.”

    ~Olana A'i, Kumu Hula

  • “I no longer say ‘Hawaiian ways of knowing’ anymore. Because people relegate that to the margins. ‘Ways of knowing,’ as if it’s a quaint, anthropologic way of describing something outside us. No, it’s ‘epistemology,’ the philosophy of knowledge. Land educates. ‘Ike ‘aina. The land of your birth educates you. This land here educates you.”

    ~Manu Meyer

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