Overwintering of the parasitic dinoflagellate Hematodinium perezi in dredged blue crabs (Callinectes sapidus) from Wachapreague Creek, Virginia

Shields, Jeffrey D.; Sullivan, Shelley E.; Small, Hamish J.

doi:10.1016/j.jip.2015.07.013

Cited by 26 publications

(25 citation statements)

References 40 publications

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Section: Discussionsupporting

confidence: 93%

“…In the work reported here, using qPCR-based analysis, infection prevalence in April varied between years with 13% prevalence in 2014 and 69% prevalence in 2015 (the vast majority of April infections being categorized as light). This is consistent with recent work that has shown over wintering crabs are capable of harboring disease (Shields et al 2015).The paradigm of a late summer to early fall peak in Hematodinium perezi infections in blue crabs from the MCBs, originally reported by Messick & Shields (2000), is consistent with what was ob served in this study (Table 1). Infection intensities matched this trend, showing a slow progression of low intensity infections early in the year, with a peak in moderate and heavy infections occurring between July and September for both years (Fig.…”

supporting

confidence: 93%

“…In April 2015, a single mud crab was found with parasite DNA levels corresponding to a moderate infection. This needs to be confirmed by histopathology but does have important implications for management of the parasite (Haydon 2002).Infection prevalence in blue crabs also fluctuates between years (Messick 1994, Pagenkopp Lohan et al 2012, Gandy et al 2015, Shields et al 2015. This held true for the current study as blue crab infection prevalence was significantly higher in 2015 than in 2014.…”

supporting

confidence: 52%

“…Although recent studies have shown that blue crabs can overwinter with infections, many of these infections are not active or are of low intensity, depending on winter temperatures (Messick et al 1999, Shields et al 2015. The possibility that overwintering crabs sporulate in early spring cannot be ruled out, as Shields et al (2015) observed that overwintering crabs rapidly developed heavy infections when moved to the lab and held at 15°C. It should be noted, however, that these temperatures are not typically seen in the MCB until May.…”

Section: Discussionmentioning

confidence: 99%

“…Variations in environmental conditions may play a determining role in host−parasite inter actions by influencing host or parasite fitness (Wolinska & King 2009), thus creating the yearly fluctuations in infection prevalence seen in H. perezi systems. For example, in a South Carolina estuary, elevated dissolved oxygen and pH levels were associated with increased rates of H. perezi infections in blue crabs (Parmenter et al 2013).Another environmental condition known to influence H. perezi infections in blue crabs is temperature (Messick et al 1999, Messick & Shields 2000, Gandy et al 2015, Shields et al 2015. Colder winter temperatures have been linked to reduced infections (Gandy et al 2015, Shields et al 2015.…”

mentioning

confidence: 99%

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Disease ecology of Hematodinium perezi in a high salinity estuary: investigating seasonal trends in environmental detection

Lycett¹,

Pitula²

2017

Dis. Aquat. Org.

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The blue crab Callinectes sapidus has seen a general decline in population levels. One factor influencing mortality is infections by Hematodinium perezi, a dinoflagellate parasite. A 2 yr study was conducted in 2014 and 2015 to monitor H. perezi DNA within the Maryland (USA) coastal bays, comparing seasonal cycles in the abundance of parasite DNA in environmental samples to parasite presence in host blue crabs. A late summer to early fall peak in H. perezi infections in blue crabs was observed, consistent with previous work. Infection intensities matched this trend, showing a slow progression of low intensity infections early in the year, with a peak in moderate and heavy infections occurring between July and September, for both years. It was hypo thesized that the peak in water column occurrence would coincide with those months when infection intensities were highest in blue crabs. As the peaks in water column occurrence were in July 2014 and August−September 2015, this is consistent with sporulation being the primary contributor to environmental detection in summer months. An additional peak in environmental detection occurred in both years during the early spring months, the cause of which is currently unknown but may be related to infections in overwintering crabs or alternate hosts. Several new crusta cean hosts were identified within this estuary, including grass shrimp Palaemonetes spp. and the sand shrimp Crangon septemspinosa, as well as the mud crab Dyspanopeus sayi. Improved knowledge of this disease system will allow for better management of this important fishery. KEY WORDS: Blue crab · Crustacean · Environment · DNA · quantitative PCR · qPCR Resale or republication not permitted without written consent of the publisherDis Aquat Org 124: [169][170][171][172][173][174][175][176][177][178][179] 2017 Epizootic events where infection prevalence reached 100% have been observed in the field, after which infections disappeared from the crab popu lation presumably due to high mortality (Messick 1994).Along the Maryland coastline, there are several oceanic bays where summer mortality events have been attributed to infections by H. perezi. For the purpose of this study, these bays are denoted as a unified system known as the Maryland coastal bays (MCB), which includes Isle of Wight, Assawoman, Sinepuxent, and Chincoteague bays, though a portion of Chincoteague Bay is in Virginia. Seasonal cycles of infection in this system suggest higher rates of infection when water temperatures are at their highest or beginning to cool from their summer peak (Messick 1994, Messick et al. 1999, Messick & Shields 2000.Although the exact mechanism of disease transmission is still unknown, there have been reports of sporulation events, where heavily infected hosts release dinospores into the water column (Shields & Squyars 2000). Despite this known connection to environmental release, limited work has investigated the hypothesis that sporulation in highly infected blue crabs leads to greater detection in the water ...

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Section: Discussionsupporting

confidence: 93%

supporting

confidence: 93%

supporting

confidence: 52%

Section: Discussionmentioning

confidence: 99%