Disease, parasite, and commensal prevalences for blue crab Callinectes sapidus at shedding facilities in Louisiana, USA

Abstract

Blue crab diseases, parasites, and commensals are not well studied in the Gulf of Mexico, and their prevalence rates have only been sporadically determined. Commercial soft shell shedding facilities in Louisiana experience high mortality rates of pre-molt crabs, and some of these deaths may be attributable to diseases or parasites. During the active shedding season in 2013, we determined the prevalence of shell disease, Vibrio spp., Lagenophrys callinectes, and Hematodinium perezi at 4 commercial shedding facilities along the Louisiana coast. We also detected Ameson michaelis and reo-like virus infections. Shell disease was moderately prevalent at rates above 50% and varied by shedding facility, collection month, and crab size. Vibrio spp. bacteria were prevalent in the hemolymph of 37% of the pre-molt crabs. Lagenophrys callinectes was highly prevalent in the pre-molt crabs, but because it is a commensal species, it may not cause high mortality rates. Hematodinium perezi was absent in all pre-molt crabs. KEY WORDS: Shell disease · Vibrio · Lagenophrys · Reo-like virus · Callinectes sapidus · MoltingResale or republication not permitted without written consent of the publisher Dis Aquat Org 112: 207-217, 2015 lence of shell disease may be high at shedding facilities due to stress and crowding (Iversen & Beardsley 1976). Vibrio spp. (Vibrionales: Vibrionaceae) are the main chitinoclastic bacteria that cause shell disease (Shields & Overstreet 2007), and infections can cause morbidity and mortality of infected crabs (Bowser et al. 1981, Shields & Overstreet 2007. Vibrio spp. infections have been correlated with mortality rates of > 80% in North Carolina shedding facilities (Sizemore 1985).Both A. michaelis and RLV are hypothesized to cause mass mortalities in shedding facilities, possibly due to crowding and cannibalism, which facilitate transmission (Messick & Sindermann 1992, Bowers et al. 2010, 2011. A. michaelis causes muscle lysis in infected crabs (Messick & Sindermann 1992). Crabs infected with A. michaelis appear lethargic, and lysed muscle is chalky white (Messick & Sindermann 1992). RLV is an RNA virus that infects hemocytes, hemopoietic, and connective tissues, the nervous system, and gills (Shields & Overstreet 2007). Crabs infected with RLV develop tremors, are lethargic, and eventually become paralyzed (Johnson 1977, Shields & Overstreet 2007. RLV may be the predominant cause of crab deaths in shedding facilities from Delaware to Florida (Bowers et al. 2011).L. callinectes is an ectocommensalistic ciliate that is prevalent on pre-molt crab gills before it is shed during ecdysis. It is usually harmless to the infested crab. However, it can occasionally cause asphyxiation, especially when a crab is stressed by low dissolved oxygen or poor water quality (Couch & Martin 1982), both of which can occur at shedding facilities.A parasitic dinoflagellate that indirectly can harm the soft shell industry is Hematodinium perezi (Coccidiniales: Syndiniaceae). H. perezi causes morbidity and mortality ...

Genome Sequence Analysis of CsRV1: A Pathogenic Reovirus that Infects the Blue Crab Callinectes sapidus Across Its Trans-Hemispheric Range

“…It is likely that CsRV1 is ubiquitous in blue crabs throughout their range. This is supported by the discovery of CsRV1 in Brazilian blue crabs, together with previously published reports that CsRV1 is present in all the North American populations sampled ( Bowers et al, 2010 ; Rogers et al, 2014 ; Flowers et al, 2015 ). The genetic divergence of the RdRP sequence of CsRV1 from Brazil, relative to North American strains, suggests that the virus has been a part of the blue crab ecology for a long time, and that the virus genome may be a useful marker to understand blue crab population connectivity over large spatial and temporal scales.…”

“…Blue crab populations are themselves subject to control by numerous factors, including predation and disease ( Johnson, 1977 ; Hines, 2007 ; Shields and Overstreet, 2007 ; Schott and Messick, 2010 ; van Montfrans et al, 2010 ). Blue crabs are infected by a pathogenic virus, C. sapidus reovirus 1 (CsRV1, also called RLV for reo-like virus), throughout the studied US range from Louisiana to Massachusetts ( Johnson, 1977 ; Bowers et al, 2010 ; Rogers et al, 2014 ; Flowers et al, 2015 ). Originally described in captive crabs, CsRV1 has been reported at an average prevalence of 20% in wild populations, with peak prevalence often exceeding 50% ( Johnson and Bodammer, 1975 ; Flowers et al, 2015 ).…”

Prevalence and distribution of three protozoan symbionts in blue crab (Callinectes sapidus) populations across Louisiana, USA

“…Reaction mixtures and thermocycling conditions described previously were modified slightly (Rogers et al 2015). Briefly, reactions (10 µl) included a negative (no template) control and a positive control of DNA extracted from ethanol-preserved hemolymph of a known infected crab provided kindly by Dr. Jeffrey Shields, Virginia Institute of Marine Science.…”

Impact of salinity changes on growth, oxygen consumption and expression pattern of selected candidate genes in the orange mud crab ( Scylla olivacea )

“…Unlike shrimp species, mud crab is usually free from disease and slower growth issues (Ahmed et al, 2013;Rogers, Taylor, Hawke, Schott, & Lively, 2015). Moreover, mud crab can be cultured with relatively low-cost feed compared with either shrimp or prawn (Cui et al, 2015;Wang et al, 2019;Wang, 2011).…”