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Project description

Sabellid polychaete detection in native gastropod populations and control at abalone culture facilities. (03XN019)
Program Exotic Pests and Diseases Research Program
Principal
investigators
E.D. Grosholz, Environmental Science & Policy, UC Berkeley
J. Moore, Medicine & Epidemiology, UC Davis
Host/habitat Abalone
Pest Sabellid
Discipline Marine Biology
Review
panel
Natural Systems
Start year (duration)  2003 (Three Years)
Objectives Determine whether sabellid infestations are currently present in native gastropod populations at 20 locations statewide that are known to, or may have been, exposed to sabellid-infested abalone.

Characterize sabellid infestations in limpets and turban snails, including generation time and the potential for infestations to be maintained through non-specific transmission.

Develop validated treatment protocols capable of killing all life stages of sabellids for use at abalone culture and holding facilities (research and educational labs, public aquaria).

Produce and distribute (to all California abalone culture and holding facilities) an educational video explaining the importance of sabellid eradication and demonstrating proper sanitization and husbandry procedures.

Project
Summary
California abalone culture facilities have been attempting to eradicate a South African shell-dwelling sabellid polychaete that causes shell deformation and greatly reduced marketability. Native intertidal gastropods are susceptible to sabellid infestation but whether sabellids have become established near infested facilities has not been sufficiently examined. We will conduct a systematic survey to determine whether infestations are present in the wild, identify which native gastropods are most susceptible to infestation, and characterize sabellid life history on these host species. Sabellid infestations persist at some facilities, we will develop control measures that result in complete destruction of all life stages and we will educate facility personnel on our findings.
Third-year
progress
We surveyed 25 abalone culture facilities, public display aquaria, and research aquaria for sabellid exposure risk. Where appropriate, we collected gastropods from intertidal habitat near these locations to determine if sabellid infestations were present. Over 1493 limpets (Lottia spp.) and 4022 turban snails (Tegula spp.) have been examined and found to be sabellid-free, leading to the conclusion that the pest has not become established in native intertidal gastropod populations statewide.

We completed a long-term transmission experiment to determine whether host-to-host transmission of sabellids can occur between individual turban snails and if so, the rate of transmission compared to that when abalone are the host species. We found that transmission of sabellids from one turban snail to another turban snail can occur, although the rate of transmission is very much lower than the corresponding rate between abalone. It appears that turban snail populations can support sabellid infestations, although they are less susceptible than abalone.

We have also completed studies to determine the minimum freshwater immersion exposure time that is lethal for all life stages of the sabellid. A 16-hour exposure was found to be necessary in laboratory trials, and a minimum 24-hour exposure is recommended for field applications such as sanitizing a production tank after one group of abalone is moved out and before another is moved in.

In a separate series of experiments, we identified the minimum freshwater exposure time necessary to kill motile sabellid larvae. A one-minute exposure was found to be necessary in laboratory trials, and use of a biocide (such as chlorine) is recommended to sanitize hands and tools when working in different production or display tanks.

Finally, we produced a DVD describing the sabellid, the threat it poses and recommended techniques for preventing sabellid acquisition and transmission. The final version of the DVD is complete and will be distributed to all abalone culturists and display facilities during April 2006. The DVD contains both English and Spanish versions of the document.

Second-year
progress
We have increased to 40 the number of abalone culture facilities, public display aquaria, and research aquaria surveyed for sabellid exposure risk. Where appropriate, we collected gastropods from intertidal habitat near these locations to determine if sabellid infestations were present. More than 1,535 limpets (Lottia spp.) and 6,565 turban snails (Tegula spp.) have been examined and found to be sabellid-free, increasing our confidence that the pest has not become established in native intertidal gastropod populations statewide.

We completed a long-term transmission experiment to determine whether host-to-host transmission of sabellids can occur between individual turban snails and if so, the rate of transmission compared to that when abalone are the host species. We found that transmission of sabellids from one turban snail to another turban snail can occur, although the rate of transmission is very much lower than the corresponding rate between abalone. It appears that turban snail populations can support sabellid infestations, although they are less susceptible than abalone.

We have also completed studies to determine the minimum freshwater immersion exposure time that is lethal for all life stages of the sabellid. A 16-hour exposure was found to be necessary in laboratory trials, and a minimum 24-hour exposure is recommended for field applications.

First-year
progress
We have collected gastropods from the intertidal adjacent to seven facilities that potentially held sabellid-positive abalone. At an additional site no gastropods were observed. Over 630 limpets (Lottia spp.) and 880 turban snails (Tegula spp.) have been examined and found to be sabellid-free. This is the beginning of our effort to determine whether sabellids have become established in any wild gastropod populations in California. At two of these facilities and at three additional facilities, we examined live abalone that are being held on-site, and these were also found to be sabellid-free. We have initiated a long-term experiment that will determine whether host-to-host transmission can occur between turban snails Tegula funebralis in the absence of abalone.

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