Little Shop of Cores: What Lives in He’eia’s Sediments

Behold: The World Beneath Our Tabis! An assortment of worms and amphipods found in sediment cores from mangrove removal areas. The plant fragments are mangrove rhizome fibers.

These invertebrates were found in sediment cores from the edge of the pond, all of them areas were mangroves had been removed (See “Old Scourge, New Questions,” January 30th). Some organisms may have been living a few centimeters underneath the sediment surface, while others may have had shallower burrows– since these samples were depth-integrated, we don’t know where these organisms dwell on a finer scale (This can be resolved by sectioning cores in the field; more on this later). While parts of the pond with low salinity are likely to be less species rich, the infauna collected today were collected on the makai side of the pond, closer to the ocean. Whether or not they are more diverse than infauna from the fresher areas of the pond is unknown at this point. If this infaunal community has changed since the mangroves were removed, we may be looking at more “pre-invasion” species which returned when the low-oxygen high-tannin environment of the mangrove sediments was ameliorated by removal. Alternatively, they could be “leftover” anoxia-tolerant species that remained even after mangrove overstory was removed.
Processing a sediment core involves sieving material through 500 µm mesh several times, fixing with formalin, staining with Rose Bengal dye overnight (hence the brilliant magenta of the worms above), and picking through a mixture of mangrove bark, algae fragments, and rhizome pieces to find brightly stained organisms. The search alone takes at least 30 minutes per core. Sorting and identification will be the next step.

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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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