THE DUSKY FARMERFISH
by
Chris Maser

The Dusky farmerfish around the Japanese islands of Ryukyu, Sesoko, and Okinawa establish and maintain monocultural farms of the red algae (seaweed known as filamentous rhodophytes) by defending them against invading grazers and by weeding out indigestible algae. To control their monocultures, the fish bite off the undesirable species of algae, swim to the edge of their territorial farms, and spit out the unwanted "weeds."1

Because the crops of red algae grow only in fish-tended monocultures, they die out if a farmerfish is removed from its farm. This, in turn, makes the algae's survival dependent on a fish's ability to maintain its farm. Since this is the only algae harvested and eaten by the fish as its staple food, the reciprocal feedback loop is one of obligatory cultivation for mutual benefit.2 In addition to simply maintaining a monocultural algae farm, however, the farmerfish inadvertently create a distinctive habitat that maintains and enhances a multi-species coexistence of foraminifera.3

ENDNOTES

  1. (1) Hiroki Hata and Makoto Kato. A Novel Obligate Cultivation Mutualism Between Damselfish And Polysiphonia Algae. Biology Letters, 2 (2006):593-596; (2) Hiroki Hata and Makoto Kato. Monoculture and mixed-species algal farms on a coral reef are maintained through intensive and extensive management by damselfishes. Journal of Experimental Marine Biology and Ecology, 313 (2004):285-296; (3) Hiroki Hata and Makoto Kato. Weeding by the herbivorous damselfish Stegastes nigricans in monocultural algae farms. Marine Ecology Progress Series, 237 (2002):227-231; and (4) Hiroki Hata and Makoto Kato. Demise of monocultural algal farms by exclusion of territorial damselfish. Marine Ecology Progress Series, 263 (2003):159-167.

  2. Ibid.

  3. (1) Hiroki Hata, Moritaka Nishihira, and S. Kamura. Effects of habitat-conditioning by the damselfish Stegastes nigricans on community structure of benthic algae. Journal of Experimental Marine Biology and Ecology, 280 (2002):95-116 and (2) Hiroki Hata and Moritaka Nishihira. Territorial damselfish enhances multi-species co-existence of foraminifera mediated by biotic habitat structuring. Journal of Experimental Marine Biology and Ecology, 270 (2002):215-240.


©chris maser 2009. All rights reserved.