Characterization and Toxic Potency of Airborne Particles Formed upon Waste from Electrical and Electronic Equipment Waste Recycling: A Case Study.

Manual dismantling, shredding, and mechanical grinding of waste from electrical and electronic equipment (WEEE) at recycling facilities inevitably lead to the accidental formation and release of both coarse and fine particle aerosols, primarily into the ambient air. Since diffuse emissions to air of such WEEE particles are not regulated, their dispersion from the recycling plants into the adjacent environment is possible. The aim of this interdisciplinary project was to collect and characterize airborne WEEE particles smaller than 1 µm generated at a Nordic open waste recycling facility from a particle concentration, shape, and bulk and surface composition perspective. Since dispersed airborne particles eventually may reach rivers, lakes, and possibly oceans, the aim was also to assess whether such particles may pose any adverse effects on aquatic organisms. The results show that WEEE particles only exerted a weak tendency toward cytotoxic effects on fish gill cell lines, although the exposure resulted in ROS formation that may induce adverse effects. On the contrary, the WEEE particles were toxic toward the crustacean zooplankter Daphnia magna, showing strong effects on survival of the animals in a concentration-dependent way.

Single-cell adaptations shape evolutionary transitions to multicellularity in green algae.

The evolution of multicellular life has played a pivotal role in shaping biological diversity. However, we know surprisingly little about the natural environmental conditions that favour the formation of multicellular groups. Here we experimentally examine how key environmental factors (predation, nitrogen and water turbulence) combine to influence multicellular group formation in 35 wild unicellular green algae strains (19 Chlorophyta species). All environmental factors induced the formation of multicellular groups (more than four cells), but there was no evidence this was adaptive, as multicellularity (% cells in groups) was not related to population growth rate under any condition. Instead, population growth was related to extracellular matrix (ECM) around single cells and palmelloid formation, a unicellular life-cycle stage where two to four cells are retained within a mother-cell wall after mitosis. ECM production increased with nitrogen levels resulting in more cells being in palmelloids and higher rates of multicellular group formation. Examining the distribution of 332 algae species across 478 lakes monitored over 55 years, showed that ECM and nitrogen availability also predicted patterns of obligate multicellularity in nature. Our results highlight that adaptations of unicellular organisms to cope with environmental challenges may be key to understanding evolutionary routes to multicellular life.

Fitness cost from fluctuating ultraviolet radiation in Daphnia magna.

Solar ultraviolet radiation (UVR) is an important environmental threat for organisms in aquatic systems, but its temporally variable nature makes the understanding of its effects ambiguous. The aim of our study was to assess potential fitness costs associated with fluctuating UVR in the aquatic zooplankter Daphnia magna. We investigated individual survival, reproduction and behaviour when exposed to different UVR treatments. Individuals exposed to fluctuating UVR, resembling natural variations in cloud cover, had the lowest fitness (measured as the number of offspring produced during their lifespan). By contrast, individuals exposed to the same, but constant UVR dose had similar fitness to control individuals (not exposed to UVR), but they showed a significant reduction in daily movement. The re-occurring threat response to the fluctuating UVR treatment thus had strong fitness costs for D. magna, and we found no evidence for plastic behavioural responses when continually being exposed to UVR, despite the regular, predictable exposure schedule. In a broader context, our results imply that depending on how variable a stressor is in nature, populations may respond with alternative strategies, a framework that could promote rapid population differentiation and local adaptation.