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Composition of macrozoobenthos and microplastics in day and night drift samples along the Vrapčak stream
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Researchers collected drift samples from an urban stream in Zagreb, Croatia, day and night, and found both macroinvertebrate drift patterns and microplastic contamination at two sampling stations. The study examines how urbanisation, light pollution, and plastic inputs combine to affect stream biodiversity and contamination.
Urbanizacija, odnosno širenje gradova, sve je češća pojava. Gradovi često pridonose svjetlosnom onečišćenju, koje remeti cirkadijane ritmove živih bića, uključujući njihove životne cikluse i migracije te drift (nizvodno otplavljivanje) makrozoobentosa u urbanim potocima. Na makrozoobentos urbanih potoka također može utjecati povećan unos mikroplastike u vodeni tok. Cilj ovog diplomskog rada jest istražiti sastav: (i) makrozoobentosa i (ii) mikroplastike u uzorcima drifta sakupljenih tijekom dana i noći na dvije postaje smještene duž urbanog potoka Vrapčak (Zagreb, Hrvatska). Dvije postaje (V1 i V2) se razlikuju, između ostalog, i u intenzitetu osvijetljenosti noću pa je postaja V1 noću neosvijetljena, a V2 je pod izravnim utjecajem ulične rasvjete. Uzorci drifta i vode uzimani su svaka dva tjedna, danju i noću, tijekom travnja i svibnja 2021. godine te je ukupno sakupljeno 48 uzoraka drifta. Osim izdvajanja i determinacije makrozoobentosa, u uzorcima drifta se provodila i analiza mikroplastike te analiza fizikalno-kemijskih parametara u uzorcima vode. Rezultati ukazuju da umjetna rasvjeta utječe na dnevno-noćne obrasce nekih skupina makrozoobentosa, međutim značajne razlike u ukupnoj gustoći drifta među postajama i dobu dana nisu dokazane. Od čestica za koje se sumnjalo da su mikroplastika (njih 47), svega dvije su sastavom odgovarale polietilenu, što ukazuje da unos mikroplastike u potok Vrapčak nije velik, odnosno da potok vjerojatno nije pod velikim antropogenim pritiskom ovakvog tipa. Većina fizikalno-kemijskih parametara se značajno razlikovala i između doba dana i među postajama. Noću su na obje postaje zabilježene povišene vrijednosti alkaliniteta i koncentracija ortofosfata te snižene vrijednosti koncentracija kisika i nitrata, temperature vode, kemijske potrošnje kisika te osvjetljenja. Utvrđeno je kako s gustoćom drifta organizama značajno korelira samo brzina strujanja vode, odnosno gustoća drifta smanjivala se s povećanjem brzine strujanja vode.
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Seasonal differences in the composition of macrozoobenthos and microplastics in sediment samples along the Vrapčak Stream
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This seasonal study of the Vrapčak Stream in Zagreb analyzed macrozoobenthos community composition and microplastic content in sediment samples collected in spring and autumn 2021 at two stations. Macroinvertebrate abundance was higher in spring and at the upstream station, with Chironomidae and Oligochaeta dominating; of 76 particles examined by spectrophotometry, 16 matched plastic polymer spectra from the literature. Water chemistry did not differ significantly between stations but varied seasonally, and the microplastic findings indicate plastic contamination even in small urban streams.
Unraveling the interplay between seasonal variations in macroinvertebrates and microplastics in urban stream sediments
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Seasonal sampling of an urban stream in Zagreb, Croatia found macroinvertebrate communities dominated by pollution-tolerant taxa while microplastic concentrations — dominated by polyethylene, polystyrene, and ethylene vinyl acetate — were higher upstream than downstream across both spring and autumn. The findings support the urban stream syndrome hypothesis and show sediment microplastics are a persistent feature of urban waterways with implications for invertebrate community health.
Distinct microplastic patterns in the sediment and biota of an urban stream
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Researchers found distinct microplastic contamination patterns between sediments and aquatic biota in an urban stream, with sediments accumulating more particles while biota showed selective uptake based on particle size and shape, highlighting the complex dynamics of microplastic distribution in urban freshwater systems.
The microplastic profile of an urban African stream
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Microplastics were detected in water, sediment, and chironomid larvae in the Braamfontein Spruit urban stream in Johannesburg, South Africa, with weirs and areas of reduced flow increasing local accumulation in sediment and invertebrates. The study demonstrates that urban stream features can concentrate microplastics and increase exposure for benthic organisms.
Microplastic pollution in streams spanning an urbanisation gradient
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Researchers sampled microplastics in small streams across an urbanization gradient and found contamination at all sites, with concentrations comparable to those in larger rivers and lakes. Fragments and small particles between 63 and 500 micrometers were the most common forms detected. Surprisingly, catchment-scale factors like population density and stormwater overflows did not predict microplastic levels well, suggesting that local-scale sources may be more important for pollution in small streams.
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