ANS Task Force
( Caulerpa taxifolia )

New Zealand MudsnailDESCRIPTION: Caulerpa is a genus of marine (salt water) algae that has a growth form with creeping rhizomes that produce tufts of colorless rhizoids (root-like structures) downward and photosynthetic branches upward. Photosynthetic assimilators (branches) assume many different forms, often with rows or whorls of leaf-like pinnules. Caulerpa taxifolia reproduces both asexually and sexually, primarily growing in small clumps. Caulerpa species that are endemic to lagoon habitats tend to have taller assimilators and longer rhizome distances between assimilators while those that thrive in high wave energy reef areas tend to express a more compact growth form.

PATHWAYS/HISTORY: Caulerpa taxifolia naturally occurs in tropical and subtropical waters of the Caribbean, Indonesia, Southeast Asia, Australia, and Hawaii. A strain of C. taxifolia was discovered off the coast of Monaco in the Mediterranean in 1984. It was probably an aquarium release or escape. Since then it has spread rapidly through the Mediterranean. The introduced C. taxifolia is believed to be a genetic clone of a single plant, exhibiting characteristics and tolerances different from other strains of C. taxifolia. The Mediterranean strain utilizes a different reproductive strategy, forms dense mats rather than growing in small isolated clumps, reaches much greater heights in terms of growth, and tolerates a wider range of temperatures, surviving between 10-31ºC.

RISKS/IMPACTS: Introduction and spread of Caulerpa species into U.S. waters remain largely unstudied so the likely impacts on U.S. coastal marine ecosystems and the subsequent economic costs remain uncertain. Based on measured thermal tolerances, its potential distribution in the U.S. is predicted to include coastal areas south of Virginia Beach, Virginia on the Atlantic coast, areas south of Stonewall Bank, Oregon on the Pacific coast, the Gulf of Mexico, Hawaii, Puerto Rico, the U.S. Virgin Islands, American Somoa, Guam, and the Northern Mariana Islands. The potential expansion of C. taxifolia throughout these waters threatens native flora and fauna, especially threatened and endangered species and poses potential economic impacts on revenues generated by commercial and recreational fisheries, tourism, and industrial facilities. Global documented impacts of Caulerpa species include competition with marine plants and macroalgae, direct and indirect impacts on marine invertebrates, direct and indirect impacts on marine vertebrates and economic impacts due to direct control costs and indirect costs associated with ecosystem alteration.

MANAGEMENT: The U.S Fish & Wildlife Service and the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) jointly develop a comprehensive program to prevent the introduction and establishment of C. taxifolia in U.S. waters.

A Prevention Program for the Mediterranean Strain of Caulerpa taxifolia (Prevention Program) was drafted. Successful implementation of objectives and actions presented within this Prevention Program are highly dependent on establishing and maintaining effective partnerships among international, federal, state, tribal, private and public organizations. In addition, existing information gaps demand the attention of scientific research to refine and update the Prevention Program to further minimize the risk of introduction, establishment, and spread of the Mediterranean strain of C. taxifolia in U.S. waters.

WHAT YOU CAN DO: Never release aquarium plants into the wild. Never transport aquatic plants from one location to another.

PROFILE based on:
Sandra Keppner, USFWS & Russell Caplen , APHIS: A Prevention Program for the Mediterranean Strain of Caulerpa taxifolia
IMAGE CREDIT: R. Woodfield, Merkel and Associates

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