Experimental infections of Orchitophrya stellarum (Scuticociliata) in American blue crabs (Callinectes sapidus) and fiddler crabs (Uca minax)

Miller, Terrence L., Small, Hamish J., Peemoeller, Bhae-Jin, Gibbs, David A., and Shields, Jeffrey D. (2013) Experimental infections of Orchitophrya stellarum (Scuticociliata) in American blue crabs (Callinectes sapidus) and fiddler crabs (Uca minax). Journal of Invertebrate Pathology, 114 (3). pp. 346-355.

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Abstract

Outbreaks of an unidentified ciliate have occurred on several occasions in blue crabs from Chesapeake Bay held during winter months in flow-through systems. The parasite was initially thought to be Mesanophrys chesapeakensis, but molecular analysis identified it as Orchitophyra stellarum, a facultative parasite of sea stars (Asteroidea). We investigated the host-parasite association of O. stellarum in the blue crab host. Crabs were inoculated with the ciliate, or they were held in bath exposures after experimentally induced autotomy of limbs in order to determine potential mechanisms for infection. Crabs inoculated with the ciliate, or exposed to it after experimental autotomy, rapidly developed fatal infections. Crabs that were not experimentally injured, but were exposed to the ciliate, rarely developed infections; thus, indicating that the parasite requires a wound or break in the cuticle as a portal of entry. For comparative purposes, fiddler crabs, Uca minax, were inoculated with the ciliate in a dose-titration experiment. Low doses of the ciliate (10 per crab) were sometimes able to establish infections, but high intensity infections developed quickly at doses over 500 ciliates per crab. Chemotaxis studies were initiated to determine if the ciliate preferentially selected blue crab serum (BCS) over other nutrient sources. Cultures grown on medium with BCS or fetal bovine serum showed some conditioning in their selection for different media, but the outcome in choice experiments indicated that the ciliate was attracted to BCS and not seawater. Our findings indicate that O. stellarum is a facultative parasite of blue crabs. It can cause infections in exposed crabs at 10–15 °C, but it requires a portal of entry for successful host invasion, and it may find injured hosts using chemotaxis.

Item ID: 30345
Item Type: Article (Research - C1)
ISSN: 1096-0805
Keywords: Ffacultative parasite; disease; portal of entry; injury; Crustacea
Funders: National Oceanic and Atmospheric Administration (NOAA), National Science Foundation, Princeton University
Projects and Grants: NOAA Saltonstall-Kennedy Program Award# 09NER038, NSF REU Supplement OCE 0723662, NSF REU Supplement OCE 0929316, Princeton University John T. Bonner Senior Thesis Fund
Date Deposited: 25 Nov 2013 02:53
FoR Codes: 07 AGRICULTURAL AND VETERINARY SCIENCES > 0704 Fisheries Sciences > 070404 Fish Pests and Diseases @ 40%
06 BIOLOGICAL SCIENCES > 0602 Ecology > 060205 Marine and Estuarine Ecology (incl Marine Ichthyology) @ 30%
06 BIOLOGICAL SCIENCES > 0608 Zoology > 060808 Invertebrate Biology @ 30%
SEO Codes: 83 ANIMAL PRODUCTION AND ANIMAL PRIMARY PRODUCTS > 8302 Fisheries - Wild Caught > 830202 Wild Caught Crustaceans (excl. Rock Lobster and Prawns) @ 30%
96 ENVIRONMENT > 9604 Control of Pests, Diseases and Exotic Species > 960407 Control of Pests, Diseases and Exotic Species in Marine Environments @ 35%
96 ENVIRONMENT > 9604 Control of Pests, Diseases and Exotic Species > 960412 Control of Plant Pests, Diseases and Exotic Species in Coastal and Estuarine Environments @ 35%
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