A checklist of epibiotic ciliates (Peritrichia and Suctoria) on the cladoceran crustaceans

A checklist of epibiont and parasite ciliates (Ciliophora) associated to rotifers (Rotifera)

A review of the ciliate (Ciliophora) species associated to rotifers as epibionts and endoparasites is presented, based on published records. Thirty rotifer species from 12 genera are known as hosts of ciliates. Among ciliates, one species of class Suctorea and 14 species of class Oligohymenophorea (12 from subclass Peritrichia, one from Hymenostomatia, and one from Astomatia) have been noted as associated to rotifers. The possible factors responsible for host prevalence of ciliates are discussed.

Passenger for millenniums: association between stenothermic microcrustacean and suctorian epibiont - the case of Eurytemora lacustris and Tokophyra sp

Epibionts often colonize the exoskeleton of crustaceans, which sometimes results in the development of a long-term relationship between them. Our present work confirmed that a specific epibiont is closely associated with the pelagic calanoid copepod Eurytemora lacustris, regardless of the region, which suggests a preserved interaction between these species. Molecular analyses revealed that the epibiont belongs to the genus Tokophrya. We also found that the level of basibiont colonization is related to its size and identified that the most intensely inhabited body parts are those located near the center of the copepod body. We hypothesize that the relationship between Eurytemora (basibiont) and Tokophrya (epibiont) was established during the Quaternary period, following which these two populations were fragmented into lakes where they survived in close interaction. In addition, we suppose that the close relationship between the two species indicates the coevolution of stenotherms. Further studies on the interactions between Eurytemora lacustris and Tokophrya are required in order to gain insight into the long-term relationship between the copepods and the epibionts.

Seasonal dynamics of the epibiont food web on Unio tumidus (Philipsson, 1788) in a eutrophic reservoir

Bivalves represent one of the most important components of freshwater zoobenthos, and their shells provide a substrate for many organisms to create epibiotic communities of predominantly facultative nature. Thus far, information regarding colonization of Unio tumidus by microorganism assemblages has been almost absent. Moreover, data on the functioning of trophic networks created by epibionts are also unavailable. Therefore, the present study aimed to examine the assemblage of epibiotic microorganisms inhabiting live and dead bivalves with regard to the physicochemical properties of the habitat and determine whether stable isotope levels in primary producers and consumers colonizing bivalve shells exhibit significant seasonal variability. The substrate characteristic and physicochemical properties of water - primarily biogenic compounds and total organic carbon clearly modified the taxonomic composition of microorganisms and the function of the trophic network. This was reflected by the increased diversity of microorganisms (phycoflora, ciliates and rotifers) on live bivalves and the increase in their abundance on dead bivalves. The level of stable isotopes exhibited clear seasonal variability in individual components of the epibiotic trophic network, whereas food preferences of the potential consumers (protozoans and rotifers) depended significantly on the availability and abundance of food.

Chronic effects of temperature and nitrate pollution on Daphnia magna: Is this cladoceran suitable for widespread use as a tertiary treatment?

Effluent clarification and disinfection are major challenges in wastewater management. The cladoceran Daphnia magna has been proposed as a cost-effective and ecosystem-friendly option to clarify and disinfect secondary effluents, but its efficacy has not been fully tested under different sewage conditions. The present study explores the effects of temperature and nitrate on the efficacy of D. magna as a tertiary treatment at two different scales (individual assays and microcosms). Individual assays were employed to determine direct effects of temperature and/or nitrate on D. magna cultured in a suspension of organic matter. Using microcosms under the same environmental conditions, we explored the clearing efficacy of D. magna interacting with a natural microbial community. Individual assays revealed that D. magna mortality increased by 17% at 26 °C, 21% at >250 mg NO3(-)/l and by 60% at 26 °C and at >250 mg NO3(-)/l, and individuals displayed reduced body size, filtering rates and fecundity when compared to those at 21 °C and <40 mg NO3(-)/l. Improved performance under these conditions was also mirrored in the microcosms, with a higher density of D. magna (>100 ind/l) at 21 °C and <40 mg NO3(-)/l compared to the number (0-21 ind/l) at 26 °C and/or >250 mg NO3(-)/l. In the microcosms at 21 °C and <40 mg NO3(-)/l, turbidity and the density of bacteria, protists and micro-metazoa decreased in relation to those at 26 °C and/or >250 mg NO3(-)/l. Each treatment developed a unique and characteristic microbial assemblage, and D. magna was identified as the major driver of the community structure of protists and micro-metazoa. This enabled us to determine taxa vulnerability to D. magna grazing, and to re-define their tolerance thresholds for nitrate. In conclusion, this study increases our knowledge of how microbes respond to temperature and nitrate pollution, and highlights that D. magna efficacy as a tertiary treatment can be seriously compromised by variable environmental conditions.