INTRODUCED MARINE SPECIES IN PAGO ... - Bishop Museum

Skelton, P. A., Algae survey report
Introduction
Introduced Marine Species Survey in Pago Pago Harbor, American Samoa.
ALGAE SURVEY REPORT
By
Posa A. Skelton
International Ocean Institute (Australia)
PO Box 1539
Townsville, QLD 4810
AUSTRALIA
This report was prepared for the Bernice P. Bishop Museum, as part of the introduced marine
species survey in American Samoa conducted in October 2002. The report analyzes the results
of algal surveys from ten sites on Tutuila Island, American Samoa, to determine their status as
invasive species.
Algae are an important component of tropical reefs providing food for many organisms including
humans, consolidating loose rubble, providing a niche for animals and plants, and complementing
the array of colors that continues to entice visitors. They are also good environmental indicators
especially when there is a change in the ecosystem such as increased nutrients or the absence
of herbivores and grazers (Hatcher and Larkum 1983). One of the more serious threats to the
marine environment is introduced invasive algae.
Invasive algae have been documented in most oceans and seas. In the Mediterranean
approximately 61 species are considered introduced, 28 in the Atlantic coast of Europe, 21 in
New Zealand, and about 20 in Southern Australia (Ribera and Boudouresque 1995). Negative
ecological impacts are known for some invasive algal species, for example Acanthophora
spicifera, Avrainvillea amadelpha, Gracilaria salicornia and Hypnea musciformis in Hawai‘i (Smith
et al. 2002), Undaria pinnatifida in New Zealand and Australia (Hay and Luckens 1987, Hay 1990,
Sanderson 1990), Codium fragile ssp. tomentosoides in North America (Carlton and Scanlon
1985), Sargassum muticum in Canada and Europe (Critchley et al. 1990), and Caulerpa taxifolia
in the Mediterranean and South Australia (Meinesz and Hesse 1991). In the tropical seas
introduced algae are poorly documented, except for the Hawaiian Islands. This may in part be
attributed to the lack of expertise in the Pacific Island countries to accurately identify species and
the low priority accorded to introduced species in the past. The smothering and subsequent
weakening of the reef structure at Kan‘eohe Bay, Hawai‘i by the introduced Kappaphycus
striatum (Smith pers. comm.) is of a grave concern as this alga (and other related Kappaphycus
species) has been introduced to most Pacific Islands for cultivation (Skelton 1998).
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