Tuesday, 1 July 2014

College of Science Postgraduate Seminar Series 8th July 2014

College of Science Postgraduate Seminar Series - Spring 2014 

8th July 2014 - 1pm - Zoology Museum (Wallace)

Effects of artificial infection of juvenile edible crabs, Cancer pagurus with the parasitic dinoflagellate, Hematodinium sp.

Amanda Smith

(PhD student, Swansea University, UK)

Amanda is a third year PhD student under the supervision of Prof. Andrew Rowley and Dr. Dan Eastwood. Amanda studied Marine Biology here at Swansea for her undergraduate dregree before completing an MRes in Aquaculture and Fisheries, which ultimately lead to this PhD. 

Parasitic dinoflagellates of the genus, Hematodinium, are thought to be significant pathogens of a wide range of crustaceans.  Much is known of the ecology and effects of this disease on the sustainability of crustacean populations but significantly less is known about the mode of transmission and fate of infected animals. Attempts have been made to transmit the disease under aquarium conditions to several species of crabs resulting in a great deal of variation in mortality levels and the timescale of disease progression. To determine if Hematodinium infections are significant drivers of mortality in juvenile edible crabs (Cancer pagurus), crabs were injected with either 1 x 105 Hematodinium trophonts from an infected animal or sterile saline. Crabs were bled every four weeks to determine the progression of infection and its effects on the numbers of circulating haemocytes. Thirty three percent of the Hematodinium-injected crabs became infected and mortality occurred between 93 and 378 days post-challenge. Infected crabs appeared to moult less frequently than their uninfected counterparts but mortality did not appear to be directly caused by Hematodinium, as there was no significant difference in the mean time to death between infected and uninfected crabs. Both Hematodiunium-infected and uninfected crabs exhibited infections by a number of other disease causing agents including haplosporidium-like parasites, fungi and bacteria. These appeared to be key drivers of the mortality observed. These studies, albeit carried out on small cohorts of edible crabs, imply that Hematodinium is not a driver of host mortality at least under aquarium conditions. 

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