Abstract
Environmental pressures, such as physical factors, diet and contaminants may affect interactions between microbial symbionts and their multicellular hosts. Despite obvious relevance, effects of antimicrobial contaminants on host-symbiont relations in non-target aquatic organisms are largely unknown. We show that exposure to antibiotics had negative effects on survival and juvenile development of the copepod Nitocra spinipes and caused significant alterations in copepod-associated bacterial communities. The significant positive correlations between indices of copepod development and bacterial diversity indicate that disruption of the microflora was likely to be an important factor behind retarded juvenile development in the experimental animals. Moreover, as evidenced by ribotype distribution in the bacterial clone libraries, the exposure to antibiotics caused a shift in dominance from Betaproteobacteria to Cardinium bacteria; the latter have been shown to cause reproductive manipulations in various terrestrial arthropods. Thus, in addition to providing evidence that the antibiotic-induced perturbation of the microbial community associates with reductions in fitness-related traits of the host, this study is the first record of a copepod serving as a host for endosymbiotic Cardinium. Taken together, our results suggest that (1) antimicrobial substances and possibly other stressors can affect micobiome and symbiont-mediated interactions in copepods and other hosts, and (2) Cardinium endosymbionts may occur in other copepods and affect reproduction of their hosts.
Highlights
Bacteria mediate a variety of interactions within and between organisms
A recently discovered bacterial symbiont causing reproductive disorders in terrestrial arthropods is the Cardinium bacteria [6,7]. It has been found in four orders of insects and in 6–7% of arthropods, a small number compared to Wolbachia, which has been detected in all insects orders and in 66% of arthropods [7,8,9]; the number of potential Cardinium host species tested so far is relatively small
In all controls and in ciprofloxacin and sulfomethoxazole treatments, 37–86% of the nauplii had developed into copepodites, whereas the development was arrested in the trimethoprim treatment, where no copepodites were observed (Figure 1B)
Summary
During the past 500 million years they have evolved diverse mechanisms to gain entry and proliferate in multicellular eukaryotes [1], with their effects on hosts ranging from harmful to beneficial [1,2]. Examples of such effects include reproduction disorders caused by the parasite Wolbachia proliferating in arthropod ovaries and testes [3] and beneficial effects from the symbiont Buchnera providing essential amino acids to their aphid hosts [4]. A recently discovered bacterial symbiont causing reproductive disorders in terrestrial arthropods is the Cardinium bacteria [6,7]. Effects of Cardinium bacteria on host fitness are largely unknown, but reproduction disorders in infected populations have been reported for the parasitoid wasp Encarsia pergandiella and the spider mites, Eotetranychnus suginamensis and Bryobia sarothamni [8,10,11,12]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
