engleski

Artificial light and microplastics footprints in urban stream drift – a pilot study

Artificial urban lighting can affect the circadian rhythms of organisms, including their life cycles and migrations. This is particularly evident in the drift (downstream transport/migration) of urban stream macrozoobenthos. The macrozoobenthos of urban streams may also be affected by increased microplastics inflow. The objective of this pilot- study was to investigate the composition of: (i) macrozoobenthos and (ii) microplastics accumulating in drift during the day and at night at two sampling sites in the urban Vrapčak stream (Zagreb, Croatia). Drift samples were collected bi-weekly, twice a day, in April and May 2021. At night, the upstream sampling site (V1) was in darkness, while the downstream site (V2) was illuminated by artificial street lighting. At site V1, Chironomidae were most numerous, and their drift densities were significantly higher during the day than at night. At site V2, drift was also dominated by Chironomidae, but there were no significant differences in their numbers between day and night. At site V1, significantly higher densities of Diptera pupae were found in the drift during the day than at night, while at site V2 significantly higher night drift densities of adult Diptera were found. At both sites, Ephemeroptera had significantly higher drift densities at night than during the day. Only two particles of microplastics (polyethylene) were found in the total 48 drift samples collected. The results of this pilot-study indicate that the Zagreb stream Vrapčak is not exposed to significant microplastic pollution, but that artificial light likely significantly affects the circadian rhythms of some macrozoobenthos taxa.

aquatic ecology ; ecosystem ; stream/river ; aquatic invertebrates

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