Seasonal dynamics of zebra mussel parasite populations

Abstract

The seasonal dynamics of 8 parasite taxa in zebra mussels Dreissena polymorpha were studied in the Meuse River (NE France) over a 3 yr period. In total, 69.5% of sampled organisms were infected. Among observed parasite species, Ophryoglena spp. and to a lesser extent Rickettsiales-like organisms (RLOs) displayed seasonal dynamics, with lower prevalence during warmer months negatively correlated with gonadal development in the host, water temperature and phytoplankton concentration. Furthermore, this study highlights a positive correlation between the prevalence rates of Ophryoglena spp. and RLOs. No temporal variations were ob served for the ciliates Sphenophrya dreissenae and Conchophthirus acuminatus. Concerning trematode infection, no defined seasonal pattern was observed. Thus, for more reliability in future biomonitoring studies involving zebra mussels, it will be important to include the influence of parasites and their temporal dynamics. KEY WORDS: Parasitism · Season · Dreissena polymorpha · BiomonitoringResale or republication not permitted without written consent of the publisher Aquat Biol 15: 145-151, 2012 146 1994). D. poly mor pha is an invasive species that has successfully colonised a wide range of ecosystems throughout Eu rope and North America, where it has become common over wide areas (McMahon 1996). Like a very large number of organisms, zebra mussels have been documented to have a variety of parasites needing one or several hosts to complete their life cycles. Among these, we focused on parasites common in our study area: (1) commensal (Conchophthi rus acu mi na tus) and parasitic ciliates (Ophryogle na spp. and Spheno phrya dreissenae), (2) intracellular bacteria (Rickettsiales-like organisms [RLOs]), and (3) 3 tre ma tode species, Phyllodistomum folium, Bu cepha lus polymor phus and Echinopary phium sp. (Molloy et al. 1997(Molloy et al. , 2001(Molloy et al. , 2005.In the framework of environmental parasitology, a better understanding of interactions between parasite species and host is necessary. However, these interactions are poorly documented in the freshwater zebra mussel, in contrast with other invertebrate species presenting an economic interest. The present study aimed to acquire information on the temporal dynamics of Dreissena polymorpha parasite populations that could help to improve standardisation of ecotoxicological studies using this species as a test organism. We conducted seasonal parasite surveys over a period of 3 yr in the Meuse River in northeastern France, and discuss herein in the relationships with mussel reproduction and environmental factors. MATERIALS AND METHODS SamplingBetween 30 and 200 zebra mussels were handpicked at between 80 and 120 cm depth from the rocky shores of the Meuse River at Commercy (48°45' 21.29" N, 5°36' 25.37" E), a relatively unpolluted site, between January 2006 and October 2008 (for more details on site physico-chemical characteristics see Minguez et al. 2009). The samples were not taken at regular intervals but they followe...

Influence of temporal variation and host condition on helminth abundance in the lizard Tropidurus hispidus from north-eastern Brazil

“…Climatic factors affect host (Hawkins et al, 2003) and parasite (Minguez & Giambérini, 2012) species distribution and survival in nature. Spatial and temporal variation play an important role in helminth species abundance and composition (Hamann et al, 2006; Brito et al, 2014a).…”