Parasite transmission between soft-bottom invertebrates:temperature mediated infection rates and mortality in Corophium volutator

Abstract

Circumstantial evidence has suggested that marine mlcrophallid ti-ematodes using gastropods Hydrobia spp. as flrst lnterlnedlate hosts, amphipods Corophlum spp. as second intermediate hosts, and various waterblrds as final hosts, may cause temperature-dependent epizootics and eventually local extinction of ~ntel-mediate host populations. Therefore, we examined experirnentally the impact of the microphallid trematode Mar~trenia subdolum on Corophluni volutator wlth special relerence to the influence of temperature, during the parasltes' transmission from s n a ~l to amphipod. Trematode infected snails and amphipods were estabhshed togtlther in experimental aquaria at temperatures of 15, 2 2 and 24C for 9 d. Amphipod surface activ~ty, survlvdl rate, parasite prevalence, lnfectioil rate, and paraslte dlstnbution both within and between amphlpod ~nti~vlduals were recorded d u n n g , or at the end of, the experiment The snalls' shedding rate of larval ti-clnatodes as a function of temperature was also e x a m ~n e d . Increasing temperature resulted 111 higher Infection levels and parasite-induced mortality in the amphipods, most Ilkely governed by a similar temperature-dependent emergence of larval trc'matodes from the snails. No transmission occurred at Ij'C, whereas at 24C the paraslte prevalence approached 100",1 and the parasite-induced mortality exceeded 50%) in relation to controls