Gracilaria parvispora (ogo)
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Gracilaria parvispora, or ogo,
is one of the most popular edible seaweeds in Hawai`i.
This red alga has become quite rare, and reproductive plants are protected
Herbarium sheets of Gracilaria parvispora
showing morphological variation from other sheet.
Gracilaria parvispora has solid, commonly compressed
branches, 1 - 4 mm in diameter, with long narrow, pointed tips. The plant
grows tall, to 30 cm or more, with a single dominant axis, 0.8 - 3.5 mm
diameter, usually with 3 orders of branching or, if more, the last order is
short, slender and spine-like. The plant is often red, but can become
light brown, light green, or almost white in areas of bright sunlight. Can
become very dark brown to almost black in habitats of low water motion or in
Gracilaria spp. are extremely variable in Hawaiian
waters. Habitats with lower water motion and salinity produce bushier,
darker plants with a more dense branching pattern.
Medullary cells thick-walled, cell sizes grading abruptly to
mostly 1-layered cortex; subcortex of 1-2 irregularly arranged layers of
cells, the immediately adjacent medullary cells, large, 90-150
mm diameter, before becoming even larger
toward center. Tetrasporangia scattered, 16 x 26
mm, commonly pear-shaped. Spermatangia
form inconspicuous saucer-like superficial depressions, frequently
confluent, surrounding cells modified. Cystocarps 2-3 mm diameter, internal
spore mass relatively small, not filling cavity; gonimoblast tissue
thin-walled; tubular nutritive cells conspicuous; pericarp with conspicuous
lateral and vertical pit connections, contents appearing star shaped.
Gracilaria parvispora is found on reef flats and areas
of sand overlying rocky substrate with moderate water motion.
Hawai‘i: Localized distribution.
Moloka‘i, O‘ahu: found Hau’ula, Coconut Island, Kane’ohe Bay, Oceanic
Institute, Ke’ehi Lagoon, One’ula Beach, and ‘Ewa.
Worldwide: Hawaiian endemic.
Gracilaria parvispora is one of the larger native red
algae in Hawai‘i, reaching lengths up to 60 cm. It prefers nutrient rich
water with low wind and water motion. This red alga was fairly common until
overharvested; the invasive G. salicornia is now dominant in G.
parvispora’s typical natural habitats on O‘ahu.
G. parvispora is endemic to Hawai‘i and is one of the
three most sought after seaweeds for food in the Hawaiian Islands (G.
coronopifolia or limu manueaua and Asparagopsis taxiformis (limu
kohu) are the other two). Over harvesting for consumption accounts for
serious shortages in the natural population. Until the 1970’s, this popular
alga was the most common limu found in Honolulu fish markets. The shortage
of G. coronopifolia and G. parvispora led to the introduction
of G. tikvahiae from Florida in the mid 1970’s for mariculture as a
possible produce replacement for the now rare native species. A law passed
in 1988 prohibits the collection of plants with "dark bumps" or cystocarps,
denoting a fertile, reproductive plant.
Extensive research has been done on the feasibility of
mariculture of this popular edible seaweed. Tank cultures have not been
successful, but recent studies have shown successful mariculture of G.
parvispora in floating baskets has high yields in the protected
environment of traditional Hawaiian fishponds.
Abbott, I.A., 1996. Limu: An ethnobotanical study of some
Hawaiian seaweeds. National Tropical Botanical Garden, Lawai, Kaua‘i,
Hawai‘i, 4th edition.
Abbott, I.A., 1999. Marine Red Algae of the Hawaiian
Islands. Bishop Museum Press, Honolulu, Hawai‘i.
Doty, M.S. 1986. Experiments with Gracilaria in
Hawai‘i, 1983-1985. Hawai‘i Botanical Science Paper, no. 46, University of
Hawai‘i (publisher), Honolulu, Hawai‘i.
Magruder, W.H., and J.W. Hunt, 1979. Seaweeds of Hawai‘i.
Oriental Publ. Co., Honolulu, Hawai‘i.
Glenn, E.P. and K. Fitzsimmons. Productivity of Long Ogo (Gracilaria
parvispora) in Floating Cages. Environmental Research Laboratory,
University of Arizona, Tucson, Arizona.
University of Arizona Fishpond Project.