Description
Phylum - Haplosporidians are parasites of marine and freshwater invertebrates, characterized by uninucleate or multinucleate cells, and propagules consisting of uninucleate spores with ornamented walls (Perkins 1990). The Haplosporidia have been placed in the phylum Acetospora in the past, and treated as a class, together with another protistan group, the Paramyxea. Recent phylogenetic analysis (small subunit RNA and ultrastructure), supports the treatment of the phylum Haplosporidia as a monophyletic sister group of the Ciliophora, Dinoflagellida, and Apicomplexa, with strongest affinities to the Ciliophora (ciliates) (Flores et al. 1996; Siddall et al. 1996).
Species Name, Genus, Synonymy - There are only two genera in the phylum Haplosporidia, and these are defined morphologically. Flores et al. (1996) found that Minchinia and Haplosporidium could not be distinguished using ribosomal RNA subunit sequences, so that the generic distinction was not supported. These two genera may be combined in the future.
Potentially Misidentified Species - Haplosporidium nelsoni (MSX) and H. costalis (Seaside Disease organism, SSO) are diseases of Crassostrea virginica (Eastern Oyster). These parasites differ from M. teredinis immunologically, genetically, and in spore morphology (Hillman et al. 1990; McGovern and Burreson 1990; Siddall et al. 1996).
Taxonomy
| Kingdom | Phylum | Class | Order | Family | Genus |
|---|---|---|---|---|---|
| Protista | Haplosporidia | Haplosporea | Haplosporida | Haplosporidiidae | Minchinia |
Synonyms
Invasion History
Chesapeake Bay Status
| First Record | Population | Range | Introduction | Residency | Source Region | Native Region | Vectors |
|---|---|---|---|---|---|---|---|
| 1987 | Established | Unknown | Cryptogenic | Regular Resident | Unknown-Marine | Unknown-Marine | Shipping(Fouling Community) |
History of Spread
Minchinia teredinis is a haplosporidian (protozoan) parasite of shipworms of the genus Teredo (Mollusca, Bivalvia). It was first discovered in Barnegat Bay NJ, infecting Teredo bartschi (Bartsch's Shipworm), T. furcifera (Forked Shipworm), and T. navalis (Naval Shpworm), but was absent from another shipworm, Bankia gouldi (Hillman 1978; Hillman 1979). This parasite was found in more than 50% of T. navalis at some stations, and appeared to be a significant cause of mortality among shipworms (Hillman et al. 1982). Initially, it was considered possible that this organism was Haplosporidium nelsoni (MSX), and that the same pathogen might infect both oysters and shipworms. However, immunoassays and morphological studies showed that the oyster and shipworm parasites were different species (McGovern and Burreson 1989), leading to the description of M. teredinis (Hillman et al. 1990).
Minchinia teredinis has so far been found only on the coast of the Northwest Atlantic, from Long Island Sound CT to Wachapreague VA (Hillman et al. 1990; McGovern and Burreson 1989). The CT and NJ sites where this parasite was found were strongly influenced by thermal effluents from nuclear power plants, and had developed populations of the introduced subtropical shipworms T. furcifera and T. bartschi (Hoagland and Turner 1980), as well as the cosmopolitan temperate T. navalis, which is considered cryptogenic in the northwest Atlantic (Carlton 1992). At Wachapreague VA, although thermal effluents are absent, T. furcifera was collected in 1989 (McGovern and Burreson 1990). Hillman et al. (1982) have suggested that the parasite was brought to Barnegat Bay with the tropical shipworms. Alternatively, it could have been introduced centuries ago from the Eastern Atlantic with T. navalis. However, T. C. Nelson had studied the life history and parasites of T. navalis and Bankia gouldi in the 1920's and had not observed M. teredeni (Hillman et al. 1982). Since the worldwide range of the parasite is unknown, speculation about its origins are premature.
History References - Carlton 1992; Hillman 1978; Hillman 1979; Hillman et al. 1982; Hillman et al. 1990; Hoagland and Turner 1980; McGovern and Burreson 1989; McGovern and Burreson 1990
Invasion Comments
Population, Range Status - The most abundant host of M. teredinis in the Chesapeake region is Teredo navalis (Naval Shipworm) which has been reported from the Atlantic north and south of the Bay mouth, and in the lower Bay at Hampton and Portsmouth VA, but probably occurs on the lower Eastern Shore as well. T. bartschi is known from one collection in Portsmouth VA, while T. furcifera has been collected at Wachapreague VA (Brown 1953; Ferguson and Jones 1949; McGovern and Burreson 1990; Scheltema and Truitt 1956). However, the parasite has only been studies at Wachepreague VA, on the Atlantic coast.
Ecology
Environmental Tolerances
| For Survival | For Reproduction | |||
|---|---|---|---|---|
| Minimum | Maximum | Minimum | Maximum | |
| Temperature (ºC) | ||||
| Salinity (‰) | 12.0 | 35.0 | 12.0 | 35.0 |
| Oxygen | ||||
| pH | ||||
| Salinity Range | poly-eu |
Age and Growth
| Male | Female | |
|---|---|---|
| Minimum Adult Size (mm) | 0.0 | 0.0 |
| Typical Adult Size (mm) | 0.0 | 0.0 |
| Maximum Adult Size (mm) | 0.0 | 0.0 |
| Maximum Longevity (yrs) | ||
| Typical Longevity (yrs |
Reproduction
| Start | Peak | End | |
|---|---|---|---|
| Reproductive Season | |||
| Typical Number of Young Per Reproductive Event |
|||
| Sexuality Mode(s) | |||
| Mode(s) of Asexual Reproduction |
|||
| Fertilization Type(s) | |||
| More than One Reproduction Event per Year |
|||
| Reproductive Startegy | |||
| Egg/Seed Form |
Impacts
Economic Impacts in Chesapeake Bay
Minchinia teredinis could be somewhat beneficial in the Chesapeake Bay region, since it is a parasite of shipworms, which are an economically important pest, causing extensive damage to wooden structures in the more saline portions of Chesapeake Bay. The dominant shipworm in Chesapeake Bay, Bankia gouldi (Gould's Shipworm), is not infected by the M. teredinis. Teredo navalis, which is a host to the parasite, is relatively rare in Chesapeake Bay, but is abundant in adjacent Atlantic waters outside the Bay, where it poses a threat to wooden structures (Scheltema and Truitt 1956). Minchinia teredinis has been found in Wachapreague Channel VA (McGovern and Burreson 1989), though its abundance and effects on T. navalis populations there have not been studied. Minchinia teredinis appears to affect the abundance of Teredo spp. In Barnegat Bay NJ, the prevalence of the parasite was correlated with reduced abundance of Teredo spp. in following years (Hillman et al. 1982). Consequently, the parasite can be seen as one of several factors, including temperature, salinity, and water quality, which can affect the incidence of shipworms and the rate of deterioration of submerged wooden structures.
When Minchinia teredinis was first discovered, it was thought that it might be conspecific with Haplosporidium (then Minchinia) nelsoni, MSX disease), and so could represent a natural reservoir for that devastating parasite of oysters (Hillman 1978; Hillman 1979). However, subsequent studies showed that the the two parasites were genetically distinct. Minchinia teredinis remains of some scientific and potential economic importance as a model for the study of haplosporidian infections (Hillman et al. 1990).
References - Hillman 1978; Hillman 1979; Hillman et al. 1982; Hillman et al. 1990; McGovern and Burreson 1989; Scheltema and Truitt 1956
Economic Impacts Outside of Chesapeake Bay
Minchinia teredinis can be seen as potentially beneficial, since it is a potentially lethal parasite of a genus of economically important marine pests, Teredo spp. (shipworms). In Barnegat Bay NJ, thermal effluents from a nuclear powerplant resulted in increased infestations of shipworms, including the native Bankia gouldi (Gould's Shipworm), the introduced tempeate Teredo navalis (Naval shipworm) and the introduced tropical T. bartschi and T. furcifera (Richards et al. 1984). Subsequent studies showed that M. teredinis was a major source of mortality among Teredo spp. populations in Barnegat Bay (Hillman et al. 1982), and that its range included Long Island Sound (CT) to Wachapreague VA (Hillman et al. 1990), though its full geographical extent is unknown. However, the disease does not appear to have been sufficiently lethal to have been considered as a potential shipworm control method .
References - Hillman et al. 1982; Hillman et al. 1990; McGovern and Burreson 1989; Scheltema and Truitt 1956
Ecological Impacts on Chesapeake Native Species
Minchinia teredinis is not known from Bankia gouldi (Gould's Shipworm), a shipworm which is probably native to the Chesapeake region, and is not known to affect other molluscan species (Hillman et al. 1982; Hillman et al. 1990). In Barnegat Bay, periods of high prevalence of M. teredinis appear to result in reduced abundance of Teredo spp. in the following year, suggesting that this parasite could indirectly influence its host's abundance. Such indirect effects of this parasite have not been studied.
References - Hillman et al. 1982; Hillman et al. 1990
Ecological Impacts on Other Chesapeake Non-Native Species
Minchinia teredinis is a parasite of the shipworm Teredo navalis (Naval shipworm), which we consider introduced in the Western Atlantic (Ruiz et al. 2000), and also of T. bartschi (Bartsch's Shipworm) and T. furcifera (Forked Shipworm) which are introduced, but of uncertain establishment in the Chesapeake Bay region (Brown 1953; McGovern and Burreson 1990). In Barnegat Bay, this parasite appears to be a major source of mortality in Teredo spp.populations (Hillman et al. 1982; Hillman et al. 1990). The parasite has been identified from Wachapreague VA (McGovern and Burreson 1989), but its impact in the population dynamics of Teredo spp. in the Chesapeake Bay region is unknown.
Parasitism - Infections of Minchinia teredinis are associated with considerable tissue damage, including lesions and sloughing of tissue in the gill epithelia, hyperplasia of digestive epithelia, and occlusion of blood vessels (Hillman et al. 1982). Correlations of parasite abundance in one season with T. navalis abundance in the next season suggested that M. teredinis was strongly influencing abundance of this shipworm (Hillman et al. 1982).
References - Hillman et al. 1982; Hillman et al. 1990; McGovern and Burreson 1989; McGovern and Burreson 1990; Ruiz et al. 2000
References
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