An acanthocephalan parasite increases the salinity tolerance of the freshwater amphipod Gammarus roeseli (Crustacea: Gammaridae)
- 317 Downloads
Studies of the influence of parasites on host fitness generally conclude that parasites have a strong negative effect on their hosts. In this study, we have investigated experimentally the role of Polymorphus minutus, an acanthocephalan parasite, on the salinity tolerance of the freshwater amphipod Gammarus roeseli, one of its intermediate hosts. Unexpectedly, P. minutus-infected gammarids were more tolerant to salinity stress than uninfected ones. The mean lethal salt concentrations for 50% mortality of hosts tested were 17.3 (infected) and 9.7 g/L (uninfected). The parasitic load (one or two parasites per host) did not affect the result. The size of hosts had no significant influence on the salinity tolerance of either infected or uninfected gammarids. The mobility of all types of gammarid decreased when the salinity exceeded 9.0 g/L, but there was no significant difference between infected and uninfected gammarids. We discuss the higher salinity tolerance of infected amphipods in relation to O2 consumption and osmoregulation. Finally, we demonstrate that the salinity tolerance is enhanced in the parasitized amphipod but without a significant change in behavior or an osmoregulatory adjustment.
KeywordsPolymorphus minutus Parasitism Acanthocephala Behavior ATPase activity
We thank Vincent Médoc (Université de Metz) for his help in gammarid sampling, Loïc Bollache (Université de Bourgogne) for the acanthocephalan parasite identification, and Philippe Rousselle (Université de Metz) for the computer software used in the behavioral study of gammarids. We thank three anonymous referees and the managing editor for their helpful comments. This study was supported by the French Ministry of Ecology and Sustainable Development as part of the 2003–2005 Biological Invasions program. We also declare that our experiments are in conformity with French laws.
- Bakker TCM, Mazzi D, Zala S (1997) Parasite-induced changes in behaviour and color make Gammarus pulex more prone to fish predation. Ecology 78:1098–1104Google Scholar
- Bentley CR, Hurd H (1993) Pomphorhynchus laevis (Acanthocephala): elevation of haemolymph protein concentrations in the intermediate host, Gammarus pulex (Crustacea: Amphipoda). Parasitology 107:193–198Google Scholar
- Carlton JT (1985) Transoceanic and interoceanic dispersal of coastal marine organisms: the biology of ballast water. Oceanogr Mar Biol 23:313–371Google Scholar
- Crompton DWT, Nickol BB (1985) Biology of the Acanthocephala. Cambridge Univ. Press, Cambridge, UKGoogle Scholar
- Holliday CW (1985) Salinity-induced changes in gill Na, K-ATPase activity in the mud fiddler crab, Uca pugnax. J Exp Biol 233:199–208Google Scholar
- Jordan PJ, Deaton LE (1999) Osmotic regulation and salinity tolerance in the freshwater snail Pomacea bridgesi and the freshwater clam Lampsilis teres. Comp Biochem Physiol A 122:199–205Google Scholar
- Lukascovics F (1959) A Polymorphus minutus lárva hatása a Gammarus roeseli Gerv. (Amphipoda) fajna. Ann Inst Biol (Tihany) Hung Acad Sci 26:31–39Google Scholar
- Mills CL, Brooks LJ (2003) Acanthocephalan parasite infection exerts a controlling influence on osmoregulation in the freshwater amphipod Gammarus pulex. Comp Biochem Physiol A 134(Suppl 1):S23Google Scholar
- Piscart C (2004) Rôle de la salinité dans la dynamique et la régulation des communautés de macroinvertébrés dulçaquicoles. Thesis, Université de Metz, Metz, FranceGoogle Scholar
- Read AF (1990) Parasites and the evolution of host sexual behaviour. In: Barnard CJ, Behnke JM (eds) Parasitism and host behaviour. Taylor & Francis, London, UK, pp 117–157Google Scholar
- Smith LD, Wonham MJ, McCann LD, Ruiz GM, Hines AH, Carlton JT (1999) Invasion pressure to a ballast-flooded estuary and an assessment of inoculant survival. Biological Invasions 14:443–489Google Scholar