Effectiveness of the California State Ban on the Sale of Caulerpa Species in Aquarium Retail Stores in Southern California

Abstract

The invasion of the aquarium strain of the green alga Caulerpa taxifolia and subsequent alteration of community structure in the Mediterranean Sea raised awareness of the potential for non-native seaweeds to impact coastal communities. An introduction of C. taxifolia in southern California in 2000, presumably from the release of aquarium specimens, cost ~$7 million for eradication efforts. Besides C. taxifolia, other Caulerpa species being sold for aquarium use also may have the potential to invade southern Californian and U.S. waters. Surveys of the availability of Caulerpa species in southern California aquarium retail stores in 2000-2001 revealed that 26 of 50 stores sold at least one Caulerpa species (52 %) with seven stores selling C. taxifolia. In late 2001, California imposed a ban on the importation, sale, or possession of nine Caulerpa species; the City of San Diego expanded these regulations to include the entire genus. To determine the effectiveness of the California ban, we resurveyed Caulerpa availability at 43 of the 50 previously sampled retail stores in southern California in ~2006, ~4 years following the ban. Of the 43 stores, 23 sold Caulerpa (53 %) with four stores selling C. taxifolia. A χ(2) test of frequency of availability before and after the California ban suggests that the ban has not been effective and that the aquarium trade continues to represent a potential vector for distributing Caulerpa specimens, including C. taxifolia. This study underscores the need for increased enforcement and outreach programs to increase awareness among the aquarium industry and aquarium hobbyists.

Effecting compliance with invasive species regulations through outreach and education of live plant retailers

“…However, regulation alone has not been effective at reducing trade in regulated plants (Diaz et al 2012;June-Wells et al 2012). If profit from trade in regulated species outweighs levied fines, for instance, retailers may continue to offer banned species for sale (Drew et al 2010), and inconsistent regulations pose challenges for multi-state retailers or their suppliers (Peters and Lodge 2009;Drew et al 2010).…”

Morphological and molecular clarification of the enigmaticCaulerpa floridanaW.R. Taylor (Chlorophyta, Bryopsidales) from the Dry Tortugas, Florida

“…Cribb, Lapointe et al, 2005). Recently, Diaz et al (2012) demonstrated the ineffectiveness of the ban raised in California in 2001 on the possession or sale of C. taxifolia and other designated Caulerpa species (see listing in introduction) in this state, suggesting that regulations, even when existing, are difficult to enforce for these organisms. Nonetheless, according to the Precautionary Principle (Cooney, 2004), Diaz et al (2012) supported the retention of the ban.…”

“…Recently, Diaz et al (2012) demonstrated the ineffectiveness of the ban raised in California in 2001 on the possession or sale of C. taxifolia and other designated Caulerpa species (see listing in introduction) in this state, suggesting that regulations, even when existing, are difficult to enforce for these organisms. Nonetheless, according to the Precautionary Principle (Cooney, 2004), Diaz et al (2012) supported the retention of the ban. Awaiting further clarification of Caulerpacean taxa found around the state of Florida, we hope that our morphological illustrations of C. floridana confirmed by DNA sequencing of historical material will facilitate identification of this beautiful species in the field, museum herbarium collections and potentially in the aquarium trade.…”

“…cnpssd.org/CaulerpaBrochure.pdf), the photographed field specimen of C. floridana by Vincent B. Hargreaves does not seem correctly identified in light of Taylor's description (1960) and our preliminary observations of the type material made at the University of Michigan Herbarium (MICH). In this context, molecular and morphological data are urgently needed to confirm the identity and separation of C. floridana from C. ashmeadii, as it applies to conservation issues such as ban effectiveness (Diaz et al, 2012) and invasive species management in the State of California (State of California Resources Agency, 2008). Moreover, C. floridana may hold subjective intrinsic value (Sandler, 2012) as an endemic species of the western Atlantic, and thus deserves further clarification as a potential member of this unique regional biotic diversity (Soulé, 1985).…”

Invasive aquatic pets: failed policies increase risks of harmful invasions

“…The aquarium ambulia (Limnophila sessiliflora), hydrilla (Hydrilla verticillata), and the "killer algae" (Caulerpa taxifolia) were placed on the Act No. 36 of 1983 and the Federal Noxious Weed List of 1999 making it illegal to import these species into the U.S.A. and South Africa, respectively (Martin and Coetzee 2011;Díaz et al 2012).…”