The combined influence of a pesticide (carbaryl) and a cyanotoxin (microcystin LR) on the life history of Daphnia pulicaria was investigated. At the beginning of the experiments animals were pulse exposed to carbaryl for 24 h and microcystins were delivered bound in Microcystis’ cells at different, sub-lethal concentrations (chronic exposure). In order to determine the actual carbaryl concentrations in the water LC–MS/MS was used. For analyses of the cyanotoxin concentration in Daphnia’s body enzyme-linked immunosorbent assay (ELISA) was used. Individual daphnids were cultured in a flow-through system under constant light (16 h of light: 8 h of dark), temperature (20°C), and food conditions (Scenedesmus obliquus, 1 mg of C l⁻¹). The results showed that in the treatments with carbaryl egg numbers per female did not differ significantly from controls, but the mortality of newborns increased significantly. Increasing microcystin concentrations significantly delayed maturation, reduced size at first reproduction, number of eggs, and newborns. The interaction between carbaryl and Microcystis was highly significant. Animals matured later and at a smaller size than in controls. The number of eggs per female was reduced as well. Moreover, combined stressors caused frequent premature delivery of offspring with body deformations such as dented carapax or an undeveloped heart. This effect is concluded to be synergistic and could not be predicted from the effects of the single stressors.

Tardigrades are microinvertebrates inhabiting almost all aquatic and terrestrial ecosystems throughout the world. They are known for their ability to enter into cryptobiosis and to survive extreme environmental conditions (e.g. lack of water, very high and low temperatures, high doses of radiation, vacuum space). Thanks to these abilities, tardigrades are excellent model organisms for various types of studies, e.g. ecological, ethological, physiological, astrobiological, biotechnological or medical, or even in integrative taxonomy. For most of these studies well-established tardigrade cultures are essential. Here we present a review of methods/protocols used in tardigrade culturing in the past. Based on this data and on our several years of experience in tardigrade culturing, we tried different methods and developed new ones that seem to be optimal. Here, we propose our own simple protocols for culturing herbivorous, omnivorous and carnivorous eutardigrade species in environmental chambers as well as in room conditions. We also describe methods for culturing rotifers, nematodes and algae, used as food sources for tardigrades. Moreover, many years of tardigrade culturing allowed us to describe the problems that may occur during culturing, explain their causes and propose solutions. We believe that these simple protocols will be very useful for many scientists planning tardigrade applications in their studies.

Under conditions of global warming, organisms are expected to track their thermal preferences, invading new habitats at higher latitudes and altitudes and altering the structure of local communities. To fend off potential invaders, indigenous communities/populations will have to rapidly adapt to the increase in temperature. In this study, we tested if decades of artificial water heating changed the structure of communities and populations of theDaphnia longispinaspecies complex. We compared the species composition of contemporaryDaphniacommunities inhabiting five lakes heated by power plants and four non-heated control lakes. The heated lakes are ca. 3–4 °C warmer, as all lakes are expected to be by 2100 according to climate change forecasts. We also genotyped subfossil resting eggs to describe past shifts inDaphniacommunity structure that were induced by lake heating. Both approaches revealed a rapid replacement of indigenousD. longispinaandD. cucullataby invaderD. galeataimmediately after the onset of heating, followed by a gradual recovery of theD. cucullatapopulation. Our findings clearly indicate that, in response to global warming, community restructuring may occur faster than evolutionary adaptation. The eventual recolonisation byD. cucullataindicates that adaptation to novel conditions can be time-lagged, and suggests that the long-term consequences of ecosystem disturbance may differ from short-term observations.

Methane, a potent greenhouse gas produced in freshwater ecosystems, can be used by methane-oxidizing bacteria (MOB) and can therefore subsidize the pelagic food web with energy and carbon. Consortia of MOB and photoautotrophs have been described in aquatic ecosystems and MOB can benefit from photoautotrophs which produce oxygen, thereby enhancing CH₄ oxidation. Methane oxidation can account for accumulation of inorganic carbon (i.e., CO₂) and the release of exometabolites that may both be important factors influencing the structure of phytoplankton communities. The consortium of MOB and phototroph has been mainly studied for methane-removing biotechnologies, but there is still little information on the role of these interactions in freshwater ecosystems especially in the context of cyanobacterial growth and bloom development. We hypothesized that MOB could be an alternative C source to support cyanobacterial growth in freshwater systems. We detected low δ¹³C values in cyanobacterial blooms (the lowest detected value −59.97‰ for Planktothrix rubescens) what could be the result of the use of methane-derived carbon by cyanobacteria and/or MOB attached to their cells. We further proved the presence of metabolically active MOB on cyanobacterial filaments using the fluorescein isothiocyanate (FITC) based activity assay. The PCR results also proved the presence of the pmoA gene in several non-axenic cultures of cyanobacteria. Finally, experiments comprising the co-culture of the cyanobacterium Aphanizomenon gracile with the methanotroph Methylosinus sporium proved that cyanobacterial growth was significantly improved in the presence of MOB, presumably through utilizing CO₂ released by MOB. On the other hand, ¹³C-CH₄ labeled incubations showed the uptake and assimilation of MOB-derived metabolites by the cyanobacterium. We also observed a higher growth of MOB in the presence of cyanobacteria under a higher irradiance regime, then when grown alone, underpinning the bidirectional influence with as of yet unknown environmental consequences.