Infection levels of plerocercoids of the tapewormTriaenophorus crassusand feeding strategy in two fish species from the ultra-oligotrophic Lake Achensee, Austria

Abstract

Thus far, high burdens of Triaenophorus crassus plerocercoids have been reported only in old age groups of coregonid and salmonid fishes. Here we show heavy infection with T. crassus in young whitefish Coregonus lavaretus in the ultra-oligotrophic and regulated Achensee in Tyrol, Austria. Prevalence of T. crassus on C. lavaretus was 100% in all age groups and abundance significantly increased with fish age. The mean annual accumulation of T. crassus was 5.2 parasites in 0- to 7-year-old C. lavaretus, and 2-year-old specimens already harboured a mean of 19.4 plerocercoids. In Arctic charr Salvelinus umbla, however, the prevalence of T. crassus was less than 16% and the majority of infected fish contained only one or two plerocercoids. Triaenophorus nodulosus was present neither in C. lavaretus nor in S. umbla. We assume that the heavy T. crassus infection in C. lavaretus is largely related to their zooplankton-dominated diet and to the characteristics of Achensee, while habitat choice and feeding strategy of the S. umbla population are seen to be the main reasons for their low burdens of T. crassus.

How to contain a tapeworm epidemic-testing the efficiency of different catch methods to reduce the translocated final hostEsox luciusin an alpine lake

“…So far,T. crassu s could only be detected in 9 of these 34 lakes in different intensities (Sichrowsky et al, 2013;Sch€ ahle et al, 2014;Schaufler et al, 2014;BAW unpublished data). It remains unknown, why in some lakes containing the same host species the parasite massively proliferates and only occurs in low numbers in others.…”

“…In Austria alone, 65% of the 34 natural alpine lakes >50 ha contain both the final and at least one second intermediate host, and thus have the potential for further outbreaks (Gassner et al, ). So far, T. crassus could only be detected in 9 of these 34 lakes in different intensities (Sichrowsky et al, ; Schähle et al, ; Schaufler et al, ; BAW unpublished data). It remains unknown, why in some lakes containing the same host species the parasite massively proliferates and only occurs in low numbers in others.…”

“…temperature, nutrients) and biotic factors (e.g. host distribution and abundance, habitat choice, prey selectivity, immune defence; Pulkkinen and Valtonen, 1999;Knudsen et al, 2004;Sch€ ahle et al, 2014;Schaufler et al, 2014). In this respect, comparative studies may reveal under which circumstances an outbreak can be expected.…”

“…Therefore, the famous Arctic charr fishery was closed for human consumption in 2005 and remains so until today (Achleitner et al, 2009;Schaufler et al, 2014). Hence, a program was initiated to significantly reduce the translocated pike population in Lake Grundlsee and to develop strategies to contain similar epidemics in Austria (Sichrowsky et al, 2013;Sch€ ahle et al, 2014;Schaufler et al, 2014) and potentially in other lakes throughout the area of distribution of T. crassus in the Northern Hemisphere (Kuperman, 1981).…”

Infestation of zooplankton with Triaenophorus and Proteocephalus procercoids (Cestoda) in a deep oligotrophic lake

“…In the Austrian Lake Fuschlsee, one single Triaenophorus procercoid out of 140 was found in an E. gracilis individual, while the remaining procercoids were observed in C. abyssorum (Sichrowsky et al, 2013). Although all C. lavaretus and ~16% of S. umbla investigated in Lake Achensee were infested with T. crassus (Schähle et al, 2014), the prevalence of the parasites was low (0.38%; maximum infection rate, 3.7%; Fig. 2), but comparable to studies from several lakes in Austria (Lahnsteiner et al, 2009;Sichrowsky et al, 2013;Schaufler et al, 2014), France (Hanzelova and Gerdeaux, 2003) or Canada (Watson and Lawler, 1965).…”