Overview
Invasive species, the plants and animals brought to the U.S. from
other countries or relocated to new areas from within the U.S., can
damage or provide competition for native plants and animals, threatening
the fabric of coastal ecosystems. Invasive species can change the community
structure of organisms within an area and cause substantial economic
and environmental damage. Stimulated by the rapid global expansion
of trade, transport, and travel, invasive species and the costs they
impose on society are increasing at an alarming rate. After habitat
destruction, biological invasion is considered to be the second largest
cause of loss of native species and of biological diversity.
The Hawaii
Coral Reef Initiative – Research Program and ECOHAB researchers are studying the impacts of invasive algae in Hawaii. The
red algae Hypnea musciformis was introduced to Hawaii’s reefs
in Oahu in 1974 to study its feasibility for aquaculture. When experimental
trials were completed, the plantings were abandoned. Thirty years later,
Hypnea has significant negative impacts on reef ecosystems. Hypnea
musciformis has spread to all of the major Hawaiian Islands, except
Hawaii. It forms blooms that generate new biomass of up to 9000kg/wk,
much of which subsequently washes up on West Maui beaches. The large
piles of decomposing biomass draw complaints from residents and drive
tourists away. A recent study has confirmed significant economic impact
of this nuisance species (up to $30 million/yr) in the form of lower
property values and lost tourist revenue. Ten years ago, Cladophora
sericea, became remarkably abundant on leeward reefs in Maui and great
blooms now occur seasonally. During the blooms, large masses of the
alga drift in the water column, snagging on coral and rock outcroppings
and smothering out the organisms beneath. The ecologically successful
green alga, Ulva fasciata, or "sea lettuce" are found in
coastal waters near harbors, industrial complexes and residential areas
with nutrient- rich and/or fresh water input. Blooms of Ulva
fasciata coat ships’ hulls, cover pilings and shorelines, and restrict
outflow pipes. U. fasciata is classified as a marine fouling organism,
and studies in control and eradication are presently underway.