Biology subjects

Gerdes, Z.

Publications and source records attributed to Gerdes, Z..

3 recordsLinked to original sources

bioRxiv2018

Microplastic-mediated transport of PCBs? A depuration study with Daphnia magna

The role of microplastic (MP) as a carrier of persistent organic pollutants (POPs) to aquatic organisms has been a topic of debate. However, theoretically, the reverse POP transport can occur at higher relative contaminant concentrations in the organism than in the microplastic. The effect of microplastic on the PCB removal in planktonic animals was evaluated using the cladoceran Daphnia magna with a high body burden of polychlorinated biphenyls (PCB 18, 40, 128 and 209) exposed to a mixture of microplastic and algae (with 77% MP by mass); daphnids exposed to only algae served as the control. As the endpoints, we used PCB body burden, growth, fecundity and elemental composition (%C and %N) of the daphnids. We found that PCB 209 was removed more efficiently in the daphnids fed with microplastic, while there was no difference for the {Sigma}PCBs between the microplastic-exposed and control animals. Effects of the microplastic exposure on fecundity were of low biological significance, even though both the starting PCB body burden and the microplastic exposure concentrations were high and greatly exceeding environmentally relevant concentrations.

pharmacology and toxicology↗

bioRxiv2018

Alterations in swimming behavior of Daphnia exposed to polymer and mineral particles: towards understanding effects of microplastics on planktonic filtrators

Concerns have been raised that microplastics (MP) can impact aquatic organisms by compromising their nutrition. However, little is understood about the mechanisms of the adverse effects of MP in suspension-feeders that routinely ingest particles of low nutritional value, such as mineral particles. We compared effects of non-edible particles (MP and kaolin) mixed with microalgae on the swimming and filtering behavior of a planktonic filtrator Daphnia magna; incubations with only algae served as controls. The following questions were addressed: (1) Are there differences in swimming movements between the daphnids exposed to MP and those exposed to kaolin? and (2) Whether occurrence of biofilm on the particle surface affects daphnid swimming and how these effects differ between the kaolin- and MP-exposed animals? We found that both kaolin and MP altered swimming, yet in opposite way, with a decrease of filtration-related movements in kaolin and their increase in MP. The difference was amplified in biofilm coated particles, indicating that daphnids spend more energy when swimming in suspension with MP, and even more when the MP have biofilm. The increased swimming activity of filtrators exposed to plastic litter decaying to microparticles may translate into changes in energy balance and growth.

ecology↗

bioRxiv2018

A serial dilution method for assessment of microplastic toxicity in suspension

The occurrence of microplastic (MP) in the environment is of global concern. MP risk assessment, however, is currently hampered by lacking ecotoxicological methods due to conceptual and practical problems with particle exposure. Natural particles of similar size as MP, e.g., clay and cellulose, occur abundantly in the environment. For MP risk assessment and regulation it must be established whether the addition of MP to these particles represents an additional hazard. We present a novel approach employing a serial dilution of MP and reference particles, in mixtures, which allows the differentiation of MP effects from other particulates. We demonstrate the applicability of the method using an immobilisation test with Daphnia magna exposed to polyethylene terephthalate (MP) and kaolin clay (reference material). In the concentration range of 0.1 to 10000 mg L-1 of total suspended solids (TSS), with MP contributing 0-100 %, the LC50 values for MP-kaolin mixtures were significantly lower compared to the pure kaolin suspension. MP particles were thus more harmful to daphnids than the reference material. The estimated threshold for %MP contribution above which higher mortality was observed was 1 % MP at 36 mg TSS L-1. This approach has a potential for standardisation of MP ecotoxicological testing as well as other particulate material of anthropogenic origin.\n\n\n\nO_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=112 SRC=\"FIGDIR/small/401331_ufig1.gif\" ALT=\"Figure 1\">\nView larger version (40K):\norg.highwire.dtl.DTLVardef@13e1153org.highwire.dtl.DTLVardef@1e37652org.highwire.dtl.DTLVardef@6d3efborg.highwire.dtl.DTLVardef@420d7a_HPS_FORMAT_FIGEXP M_FIG C_FIG

pharmacology and toxicology↗