Individual study: The apparent eradication of a locally established introduced marine polychaete Terebrasabella heterouncinata near Cayucos, California, USA
Culver C.S. & Kuris A.M. (2000) The apparent eradication of a locally established introduced marine pest. Biological Invasions, 2, 245-253
Once established, subsequent control of invasive marine species has rarely been attempted. Here an apparently successful eradication of a locally established introduced marine pest, a previously undescribed species of sabellid polychaete worm (now named Terebrasabella heterouncinata) is summarised. The polychaete was discovered in 1993 on South African abalone Haliotis sp. imported to California (USA) for aquaculture research. It was found to retard abalone growth and shells eventually become brittle, being riddled with thousands of worm tubes; it subsequently spread to all Californian abalone mariculture facilities (AMFs) causing considerable economic loss.
Study site: In 1996, a T.heterouncinata population was found at a rocky intertidal site near Cayucos, California (35º45''N, 120º95''W) below the water discharge of an infested AMF.
Water screening: A screen (a 46 cm diameter PVC pipe with 12 mm holes) was installed at the AMF to stop release of additional infested shells and other organisms (the source of the population). However, as the water was not finely filtered, benthic larvae of the sabellid could have passed through.
Clean-up operation: In the intertidal zone below the discharge area, all AMF-associated animal and shell debris, e.g. live and empty red abalone Haliotis rufescens, Tegula spp. (top shell snails) and Norrisia norrisii (kelp snail) and shells of these occupied by hermit crabs, were removed.
Tegula funebralis removal: Approximately 1.6 million black turban snails T.funebralis (over 1 cm shell width) were removed from the discharge site to decrease the number of hosts and thus the rate of sabellid transmission; the quantity removed was based on the epidemiological theory of the threshold host density for transmission.
Monitoring: In September 1996, prior to the initiation of the eradication procedures, a mark and recapture study of T.funebralis to assess transmission of the infestation was undertaken, and subsequently after the procedures in 1997 and 1998 to monitor the success of the eradication effort.
The minimum estimated population of T.heterouncinata on T.funebralis at Cayucos at the onset of the eradication program was 800,000 worms. At the end of the monitoring period transmission of the worm was no longer evident, thus it would appear that the population has been eradicated.
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