Publisher :
Place of publication :
Publication year : 2009
Thematic : Aquaculture
Language : English
Note
Gracilaria salicornia and G. parvispora were introduced to the south
reef of Moloka‘i, Hawai‘i, in the past 15–20 yr for aquaculture development.
Both species have naturalized on the reef. Gracilaria salicornia is now considered
an invasive species on O‘ahu due to its tendency to grow in dense beds that produce
undesirable windrows of thalli on the beach. There is also concern that it
reduces biodiversity and degrades habitats of reefs. We surveyed the south coast
of Moloka‘i, where both species were introduced, and measured biomass density,
growth rates, and thallus nutrient contents of G. salicornia in established
beds. Both species are found in the silt-laden, nearshore zone of the reef within
50 m of shore. Gracilaria salicornia grows in dense beds containing 475 g dry
weight m2 of biomass, but growth rates are low, 0.03%–1.28% day1. Tissue
nitrogen levels are low, suggesting that these populations are nitrogen limited.
Nevertheless, populations of G. salicornia persist and grow slowly on the reef,
whereas those of G. parvsipora are only found in areas of local nitrogen enrichment
from anthropogenic sources. Currently, G. salicornia does not appear to be
negatively affecting the reef ecology on Moloka‘i, because it is confined to the
disturbed, nearshore zone. However, its ability to grow slowly and persist under
low-nitrogen conditions allows it to form dense beds and suggests that it will
eventually spread farther along the coast.
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Keywords : amphipods
Encoded by : Pauline Carmel Joy Eje
