coronopifolia (limu manauea)
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Gracilaria coronopifolia on reef flat.
Limu manauea, or Gracilaria coronopifolia, is
one of the most popular edible endemic Hawaiian algae. Due to
overharvesting and competition with G. salicornia, limu manauea is
only locally abundant and, when reproductive, is protected by law.
Gracilaria coronopifolia has solid, cylindrical
branches, 1 - 2 mm in diameter, with short pointed tips. The plant may arise
from one to several branches that undergo frequent branching, with each
subsequent branching shorter, but not thinner, than the previous. The upper
plant becomes more densely branching and forms a small bush, to 15 cm tall,
with a rounded profile arising from a discoid holdfast. The plant is often
red, but may bleach to pink or white in bright sunlight.
Gracilaria spp. are extremely variable in Hawaiian
waters. Although normally cylindrical, the branches are frequently found
flattened, and sometimes plants are compressed throughout.
Cortex is single layer of pigmented cells 4
mm by 10 mm,
subcortical region of 3-4 layers of cells loosely arranged with extended pit
connections, providing loose tissue between cortex and large-celled medulla,
bases of hair cells common. Tetrasporangia oval, 31 by 40
mm, usually collected in clusters but
occasionally scattered, sterile cells surrounding them modified in shape and
size. Cystocarps occurring singly or in groups of 3-5, often in rows,
globose, rarely beaked, to 2 mm diam.; nutritive cells abundant.
Gracilaria coronopifolia is found on reef flats and
eroded limestone, from mid-intertidal tidepools to shallow subtidal, up to 4
Hawai‘i: Widely distributed
throughout Hawai‘i: on limestone substrate in Kaua‘i, O‘ahu, western and
central Maui, Moloka‘i, Lana‘i. Rare on basalt substrate in Maui and Hawai‘i
Worldwide: An Hawaiian
Gracilaria coronopifolia, like other Gracilaria
species, is a hardy subtidal red algae that attaches to limestone or
occasionally on basalt substrates. This species is one of the 10 most common
intertidal algae in the Hawaiian islands. It is widely distributed and was
fairly common, but due to its popularity as an edible algae, has been
seriously overharvested. The invasive alien
G. salicornia is now
dominant in many regions typical of the native habitat for G.
Gracilaria coronopifolia is endemic to Hawai‘i and is
one of the three most sought after seaweeds for food in the Hawaiian Islands
( (G. parvispora or ogo and Asparagopsis
taxiformis or limu kohu the other two). Overharvesting for
subsistence and commercial sale accounts for serious shortages in the
natural population. A law passed in 1988 prohibits the collection of plants
with "dark bumps" or cystocarps, denoting a fertile, reproductive plant. 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 more popular but rare
Abbott, I.A., 1984. Limu: An Ethnobotanical Study
of Some Hawaiian Seaweeds. National Tropical Botanical Garden. Lawai,
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, Honolulu, Hawai‘i.
Magruder, W.H., and J.W. Hunt, 1979. Seaweeds of Hawai‘i.
Oriental Publ. Co., Honolulu, Hawai‘i.
Ecological Success of Alien/Invasive Algae in Hawai‘i:
Endemic algae of Hawai‘i.
Marine Invasives in Hawai‘i:
The Indian River Lagoon Species Inventory: