Nonindigenous Species Introductions on Coral Reefs: A Need for Infonnation1

Nonindigenous species invasions have caused disruptions of native communities and detrimental economic impacts to fisheries in many temperate marine areas. However, comparatively little information exists for tropical regions, and even less is known about occurrences and impacts of nonindigenous species on coral reefs. Studies in the Tropics to date have mostly been limited to surveys in harbors and ports where corals and reef organisms are usually missing or rare and environmental conditions are usually quite different from those found on coral reefs. The few studies available for coral reefs suggest that nonindigenous species are thus far a relatively minor component of the total biota, but some species, especially introduced red algae, can be invasive and dominate reef areas. With limited information available, there is a need for studies of the occurrence and impacts of nonindigenous species that are focused on coral reef environments. This review summarizes the information for nonindigenous species from harbors, embayments, and coral reef surveys in the tropical Pacific and outlines procedures for studies to detect species introductions. THE INTRODUCTION OF nonnative marine algae, invertebrates, and fishes (hereinafter called nonindigenous species) into receptor areas where they may proliferate uncontrolled by predators or other controlling factors has become recognized as a significant disturbance to balanced native ecosystems. Nonindigenous species can rapidly monopolize energy resources, act as voracious predators, overcome endemic species, or transmit parasites and diseases that can be passed to humans through the food chain or direct exposure. Because of the serious consequences that can result from nonindigenous introductions, marine species invasions have been ranked among the most serious potential sources of stress to marine ecosystems (Carlton 1993). 1 Paper presented at the Ninth International Coral Reef Symposium, Bali, Indonesia, 27 October 2000. Manuscript accepted 5 September 2001. 2 Bishop Museum, 1525 Bernice Street, Honolulu, Hawai'i 96817. 3 E-mail: [email protected] Pacific Science (2002), vol. 56, no. 2:191-209 © 2002 by University of Hawai'i Press. All rights reserved In the last century, and more especially during the last two decades, human-related redistributions of marine shallow-water organisms have become more frequent and increasingly important in their impacts on native communities. Since the 1970s, a substantial increase in instances of exotic species invasion has occurred in harbors, ports, and other coastal ecosystems in temperate regions around the world (see Carlton 1985, Carlton and Geller 1993, Ruiz et al. 1997 for reviews). Such introductions have produced serious environmental and economic impacts at various locations. Table 1 summarizes a few of the more famous examples of marine bioinvasions that have disrupted temperate marine areas. These invasions demonstrate similar characteristics in having become more pervasive during the 1980s and 1990s and having occurred throughout many of the world's oceans. Although increased movement of larval organisms in cargo ships' ballast water is usually attributed to be the principal cause of these increases in bioinvasions (Carlton 1985, Chu et al. 1997, Smith et al. 1999, W onham et al. 2000), other factors such as release of imported exotic aquarium or aquaculture organisms or vessel hull fouling may also have made important contributions to non-