The introduced sabellid polychaete Terebrasabella heterouncinata in California: transmission, methods of control and survey for presence in native gastropod populations.

ABSTRACT The sabellid polychaete Terebrasabella heterouncinata (Fitzhugh & Rouse 1999) has a unique life history in which larvae settle on the edge of gastropod shells and rely on shell deposition to create a tube with an opening to the exterior. This worm was accidentally imported to California, USA on abalone from South Africa in the 1980s and spread with abalone shipments to most culture facilities and some public aquaria throughout the state. Its ability to infest California's native gastropods has sparked concern regarding potential establishment in intertidal habitats adjacent to facilities that held sabellid-positive abalone. We examined the ability of T. heterouncinata to transmit between individual turban snails, Tegula funebralis. We found that transmission between T. funebralis did occur, but at a significantly slower rate than that between red abalone Haliotis rufescens. During 2002 to 2006 native gastropods (turban snails and limpets) were collected at most sabellid-exposed sites and no T. heterouncinata were detected; it thus appears that this species has not become established in California. Freshwater exposure was examined as a method to kill T. heterouncinata in shell fragments that may remain after abalone are removed from production or display units. Freshwater immersion for up to 8 hours but not 16 or 32 h resulted in survival of adults and/or larvae resident in brood chambers. In a similar study, motile T. heterouncinata larvae were found to survive up to 32 sec of freshwater exposure, whereas none survived a 64-sec exposure. These data can be used by abalone culture and display facilities to establish reliable sanitization procedures to prevent T. heterouncinata transmission or reinfestation.

KEY WORDS: Terebrasabella heterouncinata, sabellid polychaete, abalone, Haliotis, Tegula funebralis, gastropod, aquaculture 

INTRODUCTION

In 1990 a California abalone (Haliotis spp.) farm first experienced what became an epidemic of animals with domed, brittle shells and deformed respiratory pores (Oakes & Fields 1996). The condition was linked to the presence of tiny (2-mm) sabellid polychaetes infesting the abalone shell. The polychaete was found to be a previously undescribed species, inadvertently imported during the mid 1980s with South African abalone that were brought in for research purposes (Kuris & Culver 1999).

This new species of fan worm, Terebrasabella heterouncinata (Sabellidae), is unique in exploiting gastropod shell deposition to create a protective tube (Fitzhugh & Rouse 1999). Motile benthic larvae emerge from a brood chamber in the adult tube and may settle on the same shell or migrate to other susceptible gastropods nearby. The settling larva secretes a mucus sheath that the abalone covers with shell material, resulting in a tube with a sealed basal end and an anterior end open to the outside of the shell (Fig. 1A). The larva metamorphoses into an adult with a branchial feeding crown (Fig. 1B). Finley et al. (2001) demonstrated that these sabellids, which are hermaphroditic, are capable of self-fertilization and, on farmed red abalone hosts, can develop and reproduce at temperatures spanning those encountered in California (11.2[degrees]C, 15.6[degrees]C, and 20.9[degrees]C). Generation time was negatively correlated with water temperature.

Although light infestations do not result in changes in shell morphology or structure, dramatic changes occur with heavy infestations of hundreds of worms on a single shell. Heavily infested abalone reduce or cease production of the prismatic layer of the shell, whereas continuing nacreous layer secretion, resulting in vertical shell growth (Kuris & Culver 1999). Over several months of culture, farmed abalone with heavy infestations develop brittle shells that are domed in shape with deformed or absent respiratory pores (Fig. 2).

The dependence of abalone production facilities on a small number of abalone seed producers resulted in the spread of T. heterouncinata infestations to nearly all of California's abalone culture facilities by 1995. The poor price obtained for abalone with stunted, deformed shells and the destruction of large numbers of submarket-size animals was directly responsible for the failure of several farms, whereas others suffered severe financial hardship from which they eventually recovered. Infestations were also discovered at public aquaria and educational facilities that purchased infested animals (Moore & Robbins, unpublished data).

Examination of nonhaliotid gastropod cohabitants in abalone production systems indicated that common intertidal gastropods such as turban snails (Tegula spp.) and limpets (Lottia spp.) were susceptible to infestation, at least under conditions of intense exposure (Kuris & Culver 1999). Culver and Kuris (2004) provided more detail on the relative susceptibility of various California gastropods when exposed to infested abalone. However, the life history traits of T. heterouncinata on nonhaliotid hosts and the ability for horizontal transmission in the absence of abalone has not been demonstrated. Almost nothing is known about the infestation dynamics on susceptible nonhaliotid gastropods (e.g., limpets and turban snails), the species that are likely to sustain and spread infestations because of they can occur at very high densities in rocky intertidal and nearshore subtidal habitats statewide.

[FIGURE 1 OMITTED]

[FIGURE 2 OMITTED]

Outside land-based farms, T. heterouncinata entered the intertidal environment as dislodged larvae in the effluent stream and via the practice of rinsing empty shells and shell debris down discharge outfalls. As feared, T. heterouncinata-infested intertidal gastropods were discovered outside one infested facility near Cayucos in 1996 (Culver & Kuris 2000). Surveys indicated the infestation was limited to the immediate discharge area (<100 M of shoreline). An extensive eradication effort was conducted, based on the concept of host-density threshold, resulting in the removal of 1.6 million gastropods (primarily turban snails, Tegula funebralis) in 1997 (Culver & Kuris 2000). Most other exposed sites have not been systematically surveyed for the presence of T. heterouncinata, and the threat of significant harm to members of California's complex benthic species assemblages has been of great concern to the marine conservation community (Kuris & Culver 1999, Culver & Kuris 2000). Although the hosts and all life stages of this worm are benthic, spread of a primary infestation to remote sites could occur by rafting of infested hosts on drifting macroalgae or possibly by floating near the water surface via a mucus thread held by surface tension (Ruck & Cook 1998).

In 1997, in parallel with the efforts being conducted at the Cayucos site, the California Department of Fish and Game developed a Sabellid Eradication Program to eliminate the pest from the state, including site-specific risk assessments and renewal of operating permits being contingent on implementation of cleanup plans. This effort has been successful in eliminating T. heterouncinata from most, if not all, infested facilities. The severe economic hardship resulting from T. heterouncinata infestation prompted a number of studies to develop methods to kill the sabellid without killing abalone, including heat (Leighton 1998), microencapsulated pesticides (Shields et al. 1998), coating the shell surface with wax, and biological control (Kuris & Culver 1999), but none have proven effective in the farm environment. Ultimately, proper hygiene and rigorous avoidance of mixing infested and uninfested stocks has been successful at eliminating T. heterouncinata from abalone culture and display facilities. Two key issues are preventing transfer of T. heterouncinata larvae as workers move from tank to tank, and preventing the retention of larvae and/or adult stages in shell fragments when one batch of abalone is moved out of a tank and another is moved in. This is particularly problematic because heavily-infested shell is unusually brittle, and many T. heterouncinata could be present in tiny (i.e., several mm in area) shell fragments that are difficult to remove from large-scale production tanks, barrels or raceways. Culver et al. (1997) conducted preliminary studies indicating that larvae can die within seconds of freshwater exposure, whereas exposure of infested shell for two hours killed adults although larvae within the brood chamber remained viable. These data helped the industry largely overcome the sabellid problem. However, at a number of facilities the eradication process was slower than anticipated and T. heterouncinata reappeared at other facilities where complete eradication was believed to have been accomplished. In this study, we formally address several issues surrounding T. heterouncinata transmission and control: (1) the extent of transmission among turban snails; (2) the distribution, if any, in natural populations of turban snails and limpets, (3) the freshwater exposures needed to control adults and larvae.

MATERIALS AND METHODS

Experimental Animals

Red abalone Haliotis rufescens were donated by The Abalone Farm, Inc., (Cayucos, CA, USA) and turban snails Tegula funebralis were collected locally at the Bodega Marine Laboratory, Bodega Bay, CA, USA. All experiments involving T. heterouncinata were conducted in the California Department of Fish and Game's Pathogen Containment Facility at the Bodega Marine Laboratory. All effluent from the Pathogen Containment Facility is chlorinated and de-chlorinated prior to release. Additionally, effluent from the wet table holding tanks containing T. heterouncinata-infested animals was passed through a 75-[micro]m filter to capture sabellid larvae. The source of T. heterouncinata included infested red abalone from various farms and display facilities in California collected from the mid 1990s through 2002.

Transmission of T. heterouncinata between Tegula funebralis

Fifty uninfested turban snails T. funebralis and fifty uninfested red abalone H. rufescens were individually tagged by gluing numeric plastic tags to the outside of each shell. All were then commingled with 15 red abalone moderately- to heavily-infested with T. heterouncinata in a 4-L container with flowing seawater at 17.8[degrees]C, a temperature conducive to reproduction of this sabellid (Finley et al. 2001). Each day, the exposed shell margins on the previously uninfested animals were examined and individuals with one to four new sabellid tubes were placed in a separate container to prevent additional recruitment. The required number of 25 newly infested individuals of each species (see later) was achieved on the 11th day of exposure, and the experiment was initiated the following day. The newly infested animals were divided into five replicate "donor" groups of five individuals each and were dispersed into to five new 4-L containers, separately for each species. The experiment was initiated with the addition of five tagged, uninfested conspecifics (as "recipients") to each of the replicate tanks. The presence of newly settled T. heterouncinata on all donors and all recipients was recorded weekly. Abalone died throughout the experiment because of the presence of an unrelated disease, withering syndrome, and the experiment ended when all of the five donor abalone in one replicate tank died. Rates of T. heterouncinata transmission for each species were compared by testing for differences in slope (Zar 1984) using tank means (Fig. 3) for recipients from the week before the first appearance of a sabellid tube through the first week with no change in settlement. For this analysis the dependent variable was defined as the tank mean value for the cumulative number of recipients that acquired at least one sabellid tube, which was considered to be the best indicator of the ability of T. heterouncinata to reproduce and spread to members of the same host species. To examine differences in intensity of infestation between the two species, we also calculated the mean number of T. heterouncinata that accumulated on donors and recipients of each species over the study period, on a per-individual basis to account for abalone mortalities. Differences between the four groups were examined with an ANOVA by Ranks test with Student-Newman-Keuls multiple comparisons. The mean temperature over the study period was 18.3[degrees]C.

[FIGURE 3 OMITTED]

Survey of Native Gastropod Populations for the Presence of T. heterouncinata

Tegula spp. (primarily T. funebralis) and several species of limpets (primarily Lottia pelta, L. digitalis, L. asmi. L. limatula. and Maclintockia scabra) were collected at intertidal locations known to have been, or suspected to have been, exposed to T. heterouncinata through release from adjacent abalone culture, holding or display facilities. Collections (Table 1) were made from 2003 to 2005 except for the South Carmel (2002), Port Hueneme (2006), and Carlsbad Lagoon (2006) sites. Sampling procedures were tailored to each site based on topography, population density and distribution, and time limitations governed by tidal cycles. The risk or extent of release was characterized as low-to-absent, low, moderate or high based subjectively on our knowledge of the number of, and period of time for which, infested abalone were present. The receiving environment susceptibility was subjectively characterized as low, moderate or high based on the proximity and density of susceptible hosts. At locations where animals were abundant, 60 individuals of each species were collected from discrete geographical units in the vicinity of the discharge or exposure zone and additional samples of 60 were taken from populations up to approximately 100 M to the north and south. A sample size of 60 allows for detection with 95% confidence if the prevalence is at least 5% (USFWS and AFS-FHS, 2004). All collected animals were examined for the presence of T. heterouncinata tubes with the aid of a dissecting microscope.

Time of Freshwater Exposure to Kill All T. heterouncinata Life Stages

Six freshly shucked H. rufescens shells on which a minimum of four live T. heterouncinata were present (identified by emerging branchial crowns) were immersed in freshwater (Bodega Marine Laboratory well water, 4 ppt salinity) for each of the following time periods: 0, 2, 4, 8, 16, or 32 h. After immersion, shells were returned to seawater and commingled with 10 live, uninfested H. rufescens for four months at 18[degrees]C. The original shells were examined for the presence of emerging sabellid crowns (as an indicator of survival) at 24 h, 48 h, and monthly thereafter. The 10 untreated "sentinel" H. rufescens were examined monthly for the presence of sabellid tubes, which would indicate survival of larval stages within brood chambers in the treated shell.

Time of Freshwater Exposure to Kill Motile T. heterouncinata Larvae

Red abalone infested with T. heterouncinata were shucked and the shells were broken apart in a dish of seawater to release the sabellid larvae present in brood chambers. Motile larvae were transferred with a Pasteur pipette to individual wells of a 12-well cell culture tray filled with seawater. The seawater was drawn off by pipette without disturbing or removing the larva and 1-mL of Bodega Marine Laboratory well water was pipetted into the well and left there for 0, 8, 16, 32, or 64 sec, followed immediately by flooding with 2.5 mL of seawater. Immediately afterward, most of the water in the well was drawn off and then refilled with more seawater to completely restore salinity. For the 0-sec time point replicates, seawater was drawn off and immediately replaced with new seawater. Larvae were observed immediately after restoring salinity, and at 20 min, 1 and 2 h later. Those capable of physical movement along the bottom of the well were scored as survivors. Ten independent trials with newly isolated larvae were conducted for each exposure period.

RESULTS

Transmission of T. heterouncinata between Tegula funebralis

At the start of the experiment, there was a mean of 1.84 [+ or -] 0.04 (mean [+ or -] se) T. heterouncinata per individual among the H. rufescens donors and 1.76 [+ or -] 0.07 per individual among the T. funebralis donors; this difference was not significant (t-test; P > 0.05). The proportions of individuals having 1, 2, 3, or 4 new tubes also did not differ between the species ([chi square] test, P > 0.05). The first newly settled T. heterouncinata was observed on an H. rufescens donor on day 112 (Fig. 3). The first newly settled sabellid on an H. rufescens recipient was observed on day 119. On day 126 the first newly settled sabellid on a T. funebralis donor was observed and the first newly settled sabellid on a T. funebralis recipient was observed on day 133.

Best-fit lines for differences in slope were used to compare the rates of transmission for H. rufescens and T. funebralis. The equations were: H. rufescens: y = -6.181 + 0.0549 x (n = 14, [R.sup.2] = 0.979); T. funebralis: y = -1.087 + 0.00936 x (n = 12, [R.sup.2] = 0.878). The slopes are significantly different (P < 0.001) indicating a higher rate of transmission between H. rufescens. At the end of the experiment, H. rufescens donors and

recipients had more new T. heterouncinata than T. funebralis donors and recipients (ANOVA By Ranks, P = 0.002; Student-Newman-Kuels multiple comparison, P < 0.05 for each comparison). Figure 4 indicates the intensities of infestation among the individuals present at each time point. The experiment ended when H. rufescens mortalities reached a level such that in one replicate tank all five donor abalone had died. On this day, H. rufescens mortalities for donors reached 19 total; among H. rufescens recipients 5 died, and for all T. funebralis only two individuals died, both of which were donors.

Survey of Native Gastropod Populations for the Presence of T. heterouncinata

Native gastropods were collected from 23 of the 25 sites where release of T. heterouncinata to the environment was known or suspected (Table 1). The number of Tegula spp. and/ or limpets (mostly Lottia spp. and McClintockia scabra) collected varied widely between sites, reflecting variation in population density. No T. heterouncinata were detected in any gastropods from any of the locations sampled. At the Davenport (B) site, effluent from the farm was released into a sea cave in a region with highly exposed, nearly vertical relief that was extremely difficult to access. Limpets were sampled 800 M north of the source and T. funebralis were sampled 500 M south of the source. Cayucos (B) is the site of the sabellid eradication reported by Culver and Kuris (2000) and sampling there used the transect locations reported in their study. The Cayucos (A) site is a separate outfall for other portions of the same farm. The Santa Barbara Channel (offshore) site was not sampled because of its lack of habitat for susceptible gastropods. All abalone and equipment at this location were removed by the operator and/or a subsequent lessee. A second site that was not sampled was a research facility in Oxnard. Discharge from this facility enters a concrete sump that leads to the forebay of a power generating facility. Periodic heat treatments (41[degrees]C, 2 h) kill all gastropods in the system. A public aquarium in San Pedro was found to harbor abalone infested with T. heterouncinata. This facility has a partially-recirculating seawater system in which effluent is periodically drained into subsurface sand, and release of T. heterouncinata is not possible. The facility is, therefore, not included in Table 1. All infested gastropods at the facility were destroyed.

[FIGURE 4 OMITTED]

Time of Freshwater Exposure to Kill All T. heterouncinata Life Stages

Survival of Adults in Treated Shells

On examination at 24 and 48 h posttreatment, sabellid branchial crown emergence was observed in all six pieces of infested abalone shell exposed to freshwater for 0 and 1 h, in three of the six shells exposed for 2 h, and in none of the shells exposed for 4, 8, 16, and 32 h (Table 2). However, reexamination of the shells at one month posttreatment revealed the presence of crowns in five of the six shells in the 4-h treatment in addition to all six shells in each of the 0-, 1-, and 2-h treatments. For the 8-h treatment no crowns were observed at the one-month observation yet one was observed two-months posttreatment.

Transmission to Untreated Abalone

At one month posttreatment, all 10 of the live H. rufescens commingled with the shells immersed in freshwater for 0, 1, or 2 h were positive for T. heterouncinata tubes. Over four months, recipients commingled with shell treated for up to 8 h became infested whereas those commingled with shell treated for 16 or 32 h did not (Table 3).

Time of Freshwater Exposure to Kill Motile T. heterouncinata Larvae

Immersion of T. heterouncinata larvae in freshwater for 8 sec caused no change in their behavior relative to unexposed controls, and motility (as an indicator of survival) was observed in all individuals immediately after and 20 min, 1 h, and 2 h after treatment (Table 4). Immersion in freshwater for 16 and 32 sec caused a dramatic reduction in survival, with two larvae being motile two hours after either treatment. No motility was seen at any time point following immersion in freshwater for 64 sec.

DISCUSSION

Transmission of T. heterouncinata between Tegula funebralis

Our studies showed that Terebrasabella heterouncinata can spread between members of a native California nonhaliotid gastropod species. Newly settled T. heterouncinata larvae on T. funebralis metamorphosed, developed, and produced viable larvae, some of which settled on the shell of the same host and others of which migrated to other T. funebralis, upon which settlement and development to the adult stage occurred. Ruck and Cook (1998) noted that in its native habitat, T. heterouncinata infested multiple gastropods and was most common in gregarious lower intertidal species, and they suggested that larval transfer between species may occur when susceptible species co-occur. The previous studies of Kuris and Culver (1999) and Culver and Kuris (2004) demonstrated that a wide variety of native California archeogastropods were susceptible to infestation when commingled with heavily infested red abalone. These findings prompted great concern regarding the potential for T. heterouncinata to become established in gastropod populations throughout the state, and potentially beyond. Our findings support the need for the efforts that were undertaken at the Cayucos site (Culver & Kuris 2000).

We found that both the rate of transmission to uninfested animals and the intensities of infestation that developed over the study period were higher among H. rufescens than among T. funebralis, indicating that the former was a more suitable host species for T. heterouncinata. Mechanisms that could account for the differing rates of transmission and intensity of infestation between H. rufescens and T. funebralis remain unclear. Culver and Kuris (2004) reported similar infestation rates for these species and several species of limpets (relative to more resistant gastropods) when exposed to heavily infested abalone shell. They identified a number of factors that may affect T. heterouncinata settlement success. H. rufescens and T. funebralis both share a lack of specific attributes that were associated with resistance to T. heterouncinata, such as the highly polished shell surface of olive shells (Olivella biplicata) and the shell cleaning behavior of the blue top snail (Calliostoma ligatum). Our results may differ from those of Culver and Kuris (2004) because our recipients were exposed to much lower intensities of infestation. Despite differences in infestation rates, the amount of time that it took newly settled T. heterouncinata to reach reproductive maturity was similar between the host species, suggesting that the relatively poor settlement on T. funebralis could be because of the ability of the host to prevent settlement rather than providing an intrinsically inferior habitat.

Within each species, the number of T. heterouncinata that settled on recipient animals was similar to the number that settled on the donors, indicating an approximately equal rate of migration from the individual harboring the sabellid parent, and settlement on that individual. Larval behavior has not been studied, e.g., whether larvae that settle on the parent's host shell migrate off the shell and return or settle directly without migration. Finley et al. (2001) reported that the time at which 50% of newly settled T. heterouncinata produced larvae was 111 days at 20.9[degrees]C, 165 days at 15.6[degrees]C, and 298 days at 11.2[degrees]C. Our findings of the first newly settled T. heterouncinata on abalone donors at day 112 and abalone recipients at day 119 at a temperature of 18.3[degrees]C agree well with these data.

Survey of Native Gastropod Populations for the Presence of T. heterouncinata

Concern over the potential establishment of T. heterouncinata in gastropod populations adjacent to infested facilities prompted us to conduct a statewide survey at all sites known or suspected to be exposed to this sabellid. This was not the first sampling of this type; since the mid1990s both the California Department of Fish and Game and researchers at the University of California, Santa Barbara conducted numerous samplings at higher-risk locations to determine whether the sabellid had become established (unpublished data). To our knowledge no T. heterouncinata were found, with the exception of the Cayueos site. Again excepting the Cayucos site, these investigations were limited in scope, yet they provided some assurance that T. heterouncinata was not becoming widely established. In every case in which sample sizes in Table 1 are low (or zero), this reflects low animal densities and correspondingly low risk of sustainable sabellid infestation. Additional sampling is warranted at high-risk sites for at least several years in the future. We also anticipate learning of additional T. heterouncinata-exposed sites that will need to be monitored.

Time of Freshwater Exposure to Kill All T. heterouncinata Life Stages

The large impact that T. heterouncinata infestations had on California abalone farm profitability and indeed survival led to rapid development of sanitary control measures. Treating production or holding units, to prevent potential carryover of T. heterouncinata that may be present on shell fragments, was identified as a critical control point, and both drying and filling units with freshwater were identified as potential control methods. Drying is effective in situations where production units can be exposed to direct sunlight, but at most facilities they are held under shade and can be difficult to completely drain. Generally freshwater treatment should provide a more reliable management technique. Culver et al. (1997) reported that preliminary studies indicated a period of more than two hours is required to kill all life stages of T. heterouncinata within infested shell. Our studies confirmed this and extend the period at which T. heterouncinata can survive to eight hours of freshwater immersion. In these studies we deliberately used well water with a salinity of 4 ppt, rather than water with a lower ionic content, so that our studies would be directly applicable to farm environments. It is possible that this elevated tonicity provided protection, or delayed onset of lethal changes, compared with use of more pure water.

In the eight-hour freshwater immersion treatment, an intact sabellid crown was observed on one of six shell treated fragments two months after treatment. Although in the absence of gastropod hosts T. heterouncinata larvae will settle on other surfaces, they die in the absence of shell deposition (unpublished observations). Therefore this individual represented an adult or subadult that survived the exposure, although it was not observed at three and four months postexposure, possibly because it died or did not emerge from its tube during the observation period. Also in the eight-hour treatment, one newly settled larva was observed among previously uninfested abalone commingled with the treated shell at one month post treatment, and two were observed at two, three, and four months posttreatment respectively. We hypothesize that the intensely hypo-osmotic environment during immersion in freshwater may result in swelling of the adult individuals within tubes, creating a plug that protects the developing stages within the brood chamber from freshwater exposure.

Culver et al. (1997) recommended treating production units with freshwater for 48 h or for 24 h with the addition of bleach.

Our findings corroborate the need for relatively long exposure periods and are in agreement with these guidelines.

Time of Freshwater Exposure to Kill Motile T. heterouneinata Larvae

Even after transmission of T. heterouncinata via transfer of animals and food have been eliminated, transfer of larvae on hands and tools could occur. The large numbers of relatively small production units that typically comprise a California abalone farm necessitates that workers access many different units on any shift, with attendant risk of sabellid transmission. Although the larvae are benthic, larvae could be transferred to hands when sorting or measuring the abalone, and aeration systems within production units result in constant or periodic pulses of air that could dislodge larvae. Culver et al. (1997) recommended rinsing tools and hands with freshwater but did not provide further guidance. Our studies showed that significantly more than a "dip" in freshwater is required to kill all larvae; an exposure period of 32 sec was insufficient. Hand-washing periods of longer than 32 sec would be quite cumbersome and the addition of biocides or the use of high-pressure spraying should be considered to provide additional protection.

CONCLUSION

Through the cooperation of industry, academia, and State authorities the sabellid infestation of California abalone appears to be nearly, if not completely eradicated, without spread to native gastropod populations. No survey can give complete assurance and higher risk sites should be revisited after several years, as the threat of infestation within non-haliotid gastropod populations is real. Proper implementation of the freshwater control techniques discussed in this paper will reduce the spread of any cryptic infestations that may still exist at abalone farms or display facilities.

ACKNOWLEDGMENTS

This research was funded by a grant (Project Number 03XN019) from the Exotic/Invasive Pests and Diseases Research Program, Statewide Integrated Pest Management Program, University of California. Support was also provided by the Marine Region, California Department of Fish and Game. Contribution number 2389, Bodega Marine Laboratory.

LITERATURE CITED

Culver, C. S., A. M. Kuris & B. Beede. 1997. Identification and management of the exotic sabellid pest in California cultured abalone. California Sea Grant College Program, La Jolla, California, Publication No. T-041.29 pp.

Culver, C. S. & A. M. Kuris. 2000. The apparent eradication of a locally established introduced marine pest. Biol. Invasions 2:245-253.

Culver, C. S. & A. M. Kuris. 2004. Susceptibility of California gastropods to an introduced South African sabellid polychaete, Terebrasabella heterouncinata. Invertebr. Biol. 123:316-323.

Finley, C. A., T. J. Mulligan & C. S. Friedman. 2001. Life history of an exotic sabellid polychaete, Terebrasabella heterouncinata: fertilization strategy and influence of temperature on reproduction. J. Shellfish Res. 20:883-888.

Fitzhugh, K. & G. W. Rouse. 1999. A remarkable new genus and species of fan worm (Polychaeta: Sabellidae: Sabellinae) associated with marine gastropods, Invertebr. Biol. 118:357-390.

Kuris, A. M. & C. S. Culver. 1999. An introduced sabellid polychaete pest infesting cultured abalones and its potential spread to other California gastropods. Invertebr. Biol. 118:391-403.

Leighton, D. 1998. Control of sabellid infestation in green and pink abalones, Haliotis fulgens and H. corrugate, by exposure to elevated water temperatures. J. Shellfish Res. 17:701-705.

Oakes, F. R. & R. C. Fields. 1996. Infestation of Haliotis rufescens shells by a sabellid polychaete. Aquaculture 140:139-143.

Ruck, K. R. & P. A. Cook. 1998. Sabellid infestations in the shells of South African mollusks: implications for abalone mariculture. J. Shellfish Res. 17:693-699.

Shields, J. D., M. A. Buchal & C. S. Friedman. 1998. Microencapsulation as a potential control technique against sabellid worms in abalone culture. J. Shellfish Res. 17:79-83.

USFWS and AFS-FHS (U.S. Fish and Wildlife Service and American Fisheries Society-Fish Health Section). 2004. Standard procedures for aquatic animal health inspections. In: AFS-FHS. FHS blue book: suggested procedures for the detection and identification of certain finfish and shellfish pathogens, 2004 edition. AFS-FHS, Bethesda, Maryland.

Zar, J. H. 1984. Biostatistical analysis, 2nd ed. Prentice-Hall, Inc., New Jersey.

JAMES D. MOORE, (1,2) * CHRISTY I. JUHASZ, (3) THEA T. ROBBINS (1) AND EDWIN D. GROSHOLZ (4)

(1) California Department of Fish and Game, Bodega Marine Laboratory, 2099 Westside Road, Bodega Bay, California 94923; 2Department of Medicine and Epidemiology, School of Veterinary Medicine, One Shields Avenue, University of California, Davis California 95616; (3) Bodega Marine Laboratory, 2099 Westside Road, Bodega Bay California 94923; (4) Department of Environmental Science and Policy, One Shields A venue, University of California, Davis California 95616

* Corresponding author. E-mail: [e-mail]

TABLE 1.
Collections of Tegula spp and various limpets from intertidal locations
(north to south) adjacent to facilities that held or may have held
sabellid-infested abalone.

Site #   Location               Tegula spp *          Limpets *

 1       Crescent City               125                  124
 2       Trinidad Harbor             144                   52
 3       Albion                        0                   58
 4       Point Arena                 263                  255
 5       Bodega Bay                  695                   90
 6       Estero Americano            110                  144
 8       Tomales Bay (A)               2                  136
 7       Tomales Bay (B)               0                    0
 9       Pillar Point Harbor          72                  198
10       Davenport (A)               261                  279
11       Davenport (B)               135                   69
12       Monterey Harbor (A)          43                    2
13       Monterey Harbor (B)         459                   62
14       South Carmel                 69                    0
16       Cayucos (A)                 583                    0
15       Cayucos (B)                1872                   15
17       Goleta                       93                  131
18       Santa Barbara            not done             not done
           Channel
19       Port Hueneme                129                   48
20       Oxnard                   not done             not done
21       Santa Monica                  0                   60
22       Redondo Beach                 0                    0
23       Terminal Island               0                   20
24       Carlsbad Lagoon              63                   20
25       La Jolla                    120                    0
         Total Animals              5238                 1763

                                  Risk or
                                 Extent of
Site #   Location                 Release         Source of Release

 1       Crescent City         Low              Suspended cage culture
 2       Trinidad Harbor       Low              Outfall from partial
                                                  recirculation
                                                  system
 3       Albion                Low              Suspended cage culture
 4       Point Arena           Low              Outfall
 5       Bodega Bay            Low to absent    Outfall
 6       Estero Americano      Moderate         Outfall
 8       Tomales Bay (A)       Moderate         Outfall
 7       Tomales Bay (B)       Low              Suspended cage culture
 9       Pillar Point Harbor   Low              Suspended cage culture
10       Davenport (A)         Low              Outfall
11       Davenport (B)         Moderate         Outfall
12       Monterey Harbor (A)   Low              Suspended cage culture
13       Monterey Harbor (B)   Moderate         Suspended cage culture
14       South Carmel          Low              Outfall
16       Cayucos (A)           Moderate         Outfall
15       Cayucos (B)           High             Outfall
17       Goleta                High             Outfall
18       Santa Barbara         Moderate         Suspended cage culture
           Channel
19       Port Hueneme          Low              Outfall
20       Oxnard                Low              Outfall
21       Santa Monica          Low to absent    Outfall to sand basin
22       Redondo Beach         Low to absent    Outfall
23       Terminal Island       Low              Outfall
24       Carlsbad Lagoon       Low              Suspended cage culture
25       La Jolla              Low              Outfall
         Total Animals

                                 Receiving
                                Environment     Receiving Environment
Site #   Location              Susceptibility        Description

 1       Crescent City            Moderate      Harbor riprap
 2       Trinidad Harbor          Moderate      Beach with
                                                  boulders/tidepools
 3       Albion                   Low           Estuary with boulders
 4       Point Arena              High          Rocky intertidal
 5       Bodega Bay               High          Rocky intertidal
 6       Estero Americano         Low           Beach & estuary
                                                  with boulders
 8       Tomales Bay (A)          Low           Tidal flat
                                                  with boulders
 7       Tomales Bay (B)          Low           Sandy beach
 9       Pillar Point Harbor      Moderate      Harbor riprap & beach
                                                  with boulders
10       Davenport (A)            High          Rocky intertidal
11       Davenport (B)            High          Rocky intertidal
12       Monterey Harbor (A)      Low           Pier pilings in sand
13       Monterey Harbor (B)      Moderate      Rocky intertidal
14       South Carmel             High          Rocky intertidal
16       Cayucos (A)              High          Rocky intertidal
15       Cayucos (B)              High          Rocky intertidal
17       Goleta                   Moderate      Rocky intertidal
18       Santa Barbara            Low           Offshore sand
           Channel
19       Port Hueneme             Low           Harbor riprap
20       Oxnard                   Low           Power plant forebay
21       Santa Monica             Low           Pier pilings in sand
22       Redondo Beach            Low           Offshore sand
23       Terminal Island          Low           Pier pilings and cement
24       Carlsbad Lagoon          Low           Lagoon with
                                                  high sedimentation
25       La Jolla                 Low           Beach with
                                                  boulders & tidepools
         Total Animals

* Tegula refers to T. funebralis, T. brunnea or T. montereyensis.

** Limpet refers to all species of limpets encountered.

TABLE 2.
Survival of Terebrasabella heterouncinata
exposed to freshwater.

                         Time of Examination PostExposure

Exposure Period   Prior   24 h   48 h   1 mo   2 mo   3 mo   4 mo

 0 h                6      6      6      6       6      6      6
 1 h                6      6      6      6      --     --     --
 2 h                6      3      3      6      --     --     --
 4 h                6      0      0      5       5      5      5
 8 h                6      0      0      0       1      0      0
16 h                6      0      0      0       0      0      0
32 h                6      0      0      0       0      0      0

Note: Six replicate shell fragments were immersed in freshwater
for each exposure period. The number of fragments with at least
one emergent sabellid crown is shown.

--, not done.

TABLE 3.
Transmission of Terebrasabella heterouncinata larvae from
infested abalone shell fragments exposed to freshwater.

                            Time of Examination after
                         Commingling with Treated Shell

Exposure Period     Prior     1 mo     2 mo     3 mo     4 mo

 0 h                  0        10       10       10       10
 1 h                  0        10       --       --       --
 2 h                  0        10       --       --       --
 4 h                  0        10       10       10       10
 8 h                  0         1        2        2        2
16 h                  0         0        0        0        0
32 h                  0         0        0        0        0

--, not done.

Note: Shown is the number of abalone (out of ten) that became
infested with at least one sabellid after commingling with
treated shell for the time periods specified.

TABLE 4.
Survival of sabellid larvae exposed to freshwater. Ten independent
trials with individual larvae were conducted for each treatment
period. The number that were observed to be motile is shown.

                        Time of Examination Posttreatment

                            Immediately
Exposure Period    Prior     Following     20 min    1 h    2 h

 0 sec              10          10           10      10     10
 8 sec              10          10           10      10     10
16 sec              10           6            5       5      2
32 sec              10           2            3       3      2
64 sec              10           0            0       0      0