01967nas a2200193   4500008004100000245008600041210006900127520135100196653002201547653001601569653001501585653001601600653002501616653001701641100002301658700001701681700003001698856004501728       2013                        eng d00aDoes the parasitic freshwater pearl mussel <i>M. margaritifera </i>harm its host?0 aDoes the parasitic freshwater pearl mussel iM margaritifera ihar3 aMany parasites have strong negative impacts on their hosts, but the effects of singlehost,non-trophically transmitted parasites can be subtle and are not well understood.We examined the physiological response of juvenile brown trout (Salmo trutta) toencystment by the parasitic larvae (glochidia) of the freshwater pearl mussel,Margaritifera margaritifera. Glochidia abundance was positively correlated to host bodysize and was accompanied by significant spleen enlargement at 31 days postexposure,but not before (15 days) of after (160 days). Compared to controls, encystedgill lamellae were significantly thicker and longer, and tended to have fewer mucouscells which may have facilitated encystment. There were no significant difference inmean blood haematocrit between encysted and uninfected trout, but encysted trouttook c. 6 hrs longer to reach basal ventilation rate than controls suggesting thatglochidiosis may impose a respiratory burden to brown trout. These findings may haveimplications for the artificial propagation of the freshwater pearl mussel because theeffects of glochidia on host respiratory performance appear to be additive. Therefore,aiming for high glochidia loads may not be the best option for mussel propagationprogrammes, if this compromises host fitness and hence the probability of successfulglochidia excystment.10afreshwater mussel10ahaematocrit10aphysiology10arespiration10asingle-host parasite10asplenomegaly1 aThomas, Gethin, R.1 aTaylor, John1 ade Leaniz, Carlos, Garcia  uhttps://galaxiids.myspecies.info/node/15