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Abstract The effect of individual and population-level egg mortality is important to quantify to maintain sustainable crustacean fisheries. The nemertean worm Carcinonemertes carcinophila (Kölliker, 1845) is an egg predator of the Atlantic blue crab, Callinectes sapidusRathbun, 1896; however, little is known about the impact this nemertean has on the reproduction of the blue crab. We assessed the prevalence and intensity of the infestation of nemerteans in ovigerous blue crabs using a fishery-independent trawl survey. During the primary spawning period of the crab, May–September 2022, 126 ovigerous females were collected and analyzed for worms. Prevalence over this time was 66.6% and mean brood infestation was 53.9 worms per infested crab host. Nemertean egg consumption was quantified with a six-day microcosm experiment. Of the 48 worms in the experiment, 71% actively fed on crab eggs and their consumption ranged 0.16–4.5 eggs day–1. Consumption rates were used to estimate population-level impact of nemertean feeding on crab brood mortality. Modeled proportions of brood loss per crab ranged 0–0.0044%. At the current prevalence and intensity of infestation, egg consumption by nemerteans has a negligible effect on blue crab reproductive output and batch fecundity in Chesapeake Bay. We also investigated the use of mature nemertean worms as a biomarker for establishing the spawning history of ovigerous female blue crabs and determined that the presence of worms in the clutch and in the gills can be used to indicate parity in ovigerous female crabs.
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Investigating conspecific CsRV1 transmission in Callinectes sapidus
A reo-like virus, CsRV1, is found in blue crabs, Callinectes sapidus, from every North American location assessed, including Chesapeake Bay and the Atlantic and Gulf coasts, USA and associated with blue crabs in softshell production. CsRV1-associated crab mortality is prevalent in captive crabs, but it is still unknown how CsRV1 is transmitted. The purpose of this study was to examine the role that conspecific predation or scavenging may play in per os transmission in single exposure and repeated exposure experiments. For viruses without cell culture propagation, repeated exposure experiments have the challenge of presenting the virus consistently during the experiment and across time replicates. In a single-exposure experiment, none of the crabs fed muscle tissue of crabs carrying intense infections of CsRV1 developed CsRV1 infections. In a repeated-exposure trial, using infected muscle tissue prepared in alginate blocks, CsRV1 was detected in 11% of the crabs fed infected tissue but was not significantly different from the control group fed alginate lacking CsRV1. For repeated per os exposure experiments, the study demonstrated the utility of using alginate to present the same homogenous sample of virus, both injected and per os, over time for oral challenge experiments. Conspecific predation and scavenging could be a transmission route, but future work into this and other possible routes of transmission for CsRV1 is important to better understand the role this virus plays in wild crab populations and the soft-shell crab industry.
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- Award ID(s):
- 1658466
- PAR ID:
- 10557820
- Publisher / Repository:
- Journal of Invertebrate Pathology
- Date Published:
- Journal Name:
- Journal of Invertebrate Pathology
- Volume:
- 201
- Issue:
- C
- ISSN:
- 0022-2011
- Page Range / eLocation ID:
- 107987
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1016/j.jip.2023.107987
