Abundance and Spread of the Invasive Red Algae, Kappaphycus spp., in Kane’ohe Bay, Hawai’i and an Experimental Assessment of Management Options

Abstract

Several species of Kappaphycus were intentionally introduced into Kane'ohe Bay, Hawai'i in the 1970s. Subsequent research has demonstrated that these algae have spread rapidly throughout the bay and can be found in a variety of reef habitats overgrowing and killing corals. This study was conducted to (a) quantify Kappaphycus spp. abundance both spatially and temporally, and (b) investigate control options including manual removal and the use of biocontrol agents. Kappaphycus spp. distribution has increased in the bay over the period between surveys conducted in 1999 and 2002, with variation among reefs. The biomass of Kappaphycus spp. removed, and the amount of time required to manually remove them from the reef varied with habitat type, but in all cases amounted to at least 10 kg/m 2 requiring almost 2 person-hours to clear 1 m 2 . Re-growth of the algae following their removal was rapid at most sites, likely due to the experimentally demonstrated ability of the algae to re-grow from minute attachment points and the low palatability of the algae to native herbivorous fishes. The native sea urchin, Tripneustes gratilla, reduced the biomass of Kappaphycus spp. in small experimental enclosures and may be a useful biocontrol agent. Because Kappaphycus spp. are still spreading in Kane'ohe Bay and can overgrow over 50% cover on some reefs, we recommend that rapid management action be taken to prevent further damage and spread to other Hawaiian coral reefs.

A molecular method for identification of the morphologically plastic invasive algal genera Eucheuma and Kappaphycus (Rhodophyta, Gigartinales) in Hawaii

“…Degradation of the Kaneohe Bay patch reefs appears to be proceeding by overgrowth of a species that has been generally identified as Kappaphycus sp. (Rodgers and Cox 1999;Woo 2000;Conklin and Smith 2005). Here, we tentatively revise its identification to Eucheuma clade E (Fig.…”

“…Understanding the distributional spread of the three eucheumoid species in Hawaii is complicated by their morphological plasticity and paucity of diagnostic morphological characters for identification (Lluisma and Ragan 1995;Conklin and Smith 2005;Zuccarello et al 2006). …”

Molecular identification of the exotic lineage of <i>Kappaphycus alvarezii</i> (Rhodophyta, Solieriaceae) cultivated in the tropical region of Brazil

“…The clade B was formed by a different Kappaphycus species. Some authors dispute the identification inconsistency of this material; however, this clade represents a single wild seaweed haplotype from Hawaii and expresses invasive characteristics only in Hawaii (Conklin & Smith 2005, Zuccarello et al 2006, Conklin et al 2009. Kappaphycus cottonii was shown to be a highly divergent sister taxon to the all other Kappaphycus samples, and more studies are needed to investigate the taxonomy of this species (Zuccarello et al 2006, Tan et al 2013.…”

“…Silva in Silva et al (1996: 334) and Eucheuma spp. have been reported in bioinvasion events in Hawaii (Smith et al 2002, Conklin & Smith 2005, India (Bagla 2008, Chandrasekaran et al 2008, Kamalakannan et al 2010 and Venezuela (Barrios 2005, Barrios et al 2007). In addition, recently Halling et al (2013) observed K. alvarezii, which was introduced from Asia for mariculture purposes, growing on coral reefs in Zanzibar.…”

The commercial red seaweed Kappaphycus alvarezii—an overview on farming and environment

“…Reports of regional farming introductions and/or development after Ask et al (2001) are cited in this review. As farming operations expanded, growing apprehensions over the impact of the introduction of exotic species to new environments, their interactions with endemic species, and its effect on biodiversity were also reported (Russell 1983;Woo 2000;Smith et al 2002;Conklin and Smith 2005;Pereira and Verlecar 2005;Anon 2006;Vijayalakshmi 2007;Chandrasekaran et al 2008). However, after four decades of introductions resulting in Kappaphycus being the most widely cultivated commercial eucheumoid, there are only a few Environmental Impact Assessment (EIA) studies addressing the ecological impacts of K. alvarezii on the environment (Tewari et al 2006;Tewari 2006), even though recommendations for EIA studies have been suggested by researchers (Woo et al 1989;Mesia and Mapelamao 2006) and organizations (National Academy of Agricultural Sciences, India 2003).…”