Vplivi nitratov na rake iz rodu slepih postranic (Amphipoda: Niphargus sp.)

Poje, Maruša (avtor), Jemec Kokalj, Anita (mentor), Fišer, Cene (komentor)

Podzemne vode in njihovi ekosistemi človeku nudijo veliko ekosistemskih storitev, med drugim čisto pitno vodo. Grožnjo tem ekosistemom med drugim predstavlja onesnaževanje. Zaradi vsesplošne rabe dušikovih gnojil v poljedelstvu so nitrati (NO3ˉ) med pogostimi onesnažili voda. Ekotoksikoloških raziskav, v katerih bi na podzemnih organizmih preizkušali vpliv nitratov, je malo. V našem magistrskem delu smo tako želeli proučiti vpliv nitratov na pet vrst iz rodu slepih postranic (Niphargus sp.), ki so se med seboj razlikovale po ekologiji (vrsti N. podpecanus in N. stygius sta bili nabrani v podzemnih vodah, vrste N. sphagnicolus, N. spinulifemur in N. timavi pa v izvirih). Voda na vzorčnih mestih z nitrati ni bila onesnažena, povsod so koncentracije znašale pod 5 mg NO3ˉ/L. Odrasle osebke vseh vrst in mladiče N. podpecanus ter N. stygius smo po > 4-tedenski aklimaciji v jamskem laboratoriju (12 ± 1 °C) 21 dni izpostavljali različnim koncentracijam nitratov, ki smo jih pripravili iz natrijevega nitrata (NaNO3). Dnevno (razen ob sobotah in nedeljah) smo beležili prizadetost in smrtnost poskusnih živali. Pri vseh vrstah smo določili toleranco za dosti višje koncentracije nitratov v primerjavi s koncentracijami, ki jih najdemo v okolju (vrednosti 96-urne EC50 so znašale med 1664 mg NO3ˉ/L in 5848 mg NO3ˉ/L, vrednosti 21-dnevne LC50 pa med 1735 mg NO3ˉ/L in 4266 mg NO3ˉ/L). Med odraslimi osebki je bila na nitrate najbolj občutljiva vrsta N. timavi (96-urna EC50 1664 mg NO3ˉ/L, 21-dnevna LC50 1735 mg NO3ˉ/L). Med podzemnimi in izvirskimi vrstami nismo beležili opaznih razlik v občutljivosti na nitrate. Po končani izpostavitvi smo v obdobju 96 ur v kontrolnem mediju M4 beležili izboljšanje stanja preživelih poskusnih osebkov. Le ti v večini primerov niso več kazali znakov prizadetosti. Dodatno smo pri vrstah N. podpecanus in N. stygius testirali tudi vpliv nitratov na mladiče. V nasprotju z našim pričakovanjem smo opazili manj prizadetih mladičev kot odraslih osebkov iste vrste, kar pa je deloma posledica uporabljene metodologije. Stopnja tolerance za nitrate je tudi pri mladičih visoka. Primerjalno smo po standardu (OECD 202, 2004) nitratom 72 ur izpostavljali tudi vodne bolhe Daphnia magna. Vrsti N. timavi in N. stygius sta bili po 72 urah izpostavitve bolj občutljivi na nitrate, vrsta N. sphagnicolus pa je imela statistično enako EC50. Zaradi uporabe visokih koncentracij nitratov smo kljub menjavanju medija med poskusom opazili pojav mikrobne razrasti.

• Jezik: Slovenski jezik
• Ključne besede: podzemne vode, Niphargus sp., nitrati, strupenost
• Vrsta gradiva: Magistrsko delo/naloga
• Tipologija: 2.09 - Magistrsko delo
• Organizacija: BF - Biotehniška fakulteta
• Založnik: [M. Poje]
• Leto izida: 2025
• PID: 20.500.12556/RUL-166713
• UDK: 595.380:504.5:631.842(043.2)
• COBISS.SI-ID: 224477699
• Datum objave v RUL: 23.01.2025

POJE, Maruša, 2025, Vplivi nitratov na rake iz rodu slepih postranic (Amphipoda: Niphargus sp.) [na spletu]. Magistrsko delo. M. Poje. [Dostopano 21 april 2025]. Pridobljeno s: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=slv&id=166713

Sekundarni jezik

• Jezik: Angleški jezik
• Naslov: Effects of nitrates on amphipod crustaceans (Amphipoda: Niphargus sp.)

Izvleček

Groundwater and its ecosystems provide many ecosystem services to humans, including clean drinking water. Pollution poses a threat to these ecosystems and one of the most common pollutants is nitrate (NO3ˉ), mainly due to the widespread use of nitrogen fertilisers in agriculture. There are only a few ecotoxicological studies testing the effects of nitrate on groundwater organisms. In our MSc thesis, we therefore investigated the effects of nitrates on five species of subterranean amphipod crustaceans (Niphargus sp.) that differed in ecology (N. podpecanus and N. stygius were collected in subterranean waters, N. sphagnicolus, N. spinulifemur and N. timavi were collected in springs). The water at the sampling sites was not contaminated with nitrates, i.e., the concentrations were below 5 mg NO3ˉ/L at all sites. Adults of all species and juveniles of N. podpecanus and N. stygius were exposed to different concentrations of nitrates prepared from sodium nitrate (NaNO3) for 21 days after at > 4 weeks of acclimation at 12 ± 1 °C and darkness. We recorded daily (except on Saturdays and Sundays) the number of dead and visually affected animals. High nitrate tolerance was observed in all species (96-h EC50 from 1664 mg NO3ˉ/L to 5848 mg NO3ˉ/L, and 21-day LC50 from 1735 mg NO3ˉ/L to 4266 mg NO3ˉ/L). Among the adults, N. timavi proved to be the most sensitive species, with 96-h EC50 and 21-day LC50 values of 1664 mg NO3ˉ/L and 1735 mg NO3ˉ/L, respectively. We did not observe a higher or lower nitrate tolerance for the two subterranean species compared to spring-collected species. During the 96-hour post-exposure period in the control medium M4 a recovery of the test specimens was observed. Nitrate effects were also tested on N. podpecanus and N. stygius juveniles. Contrary to our expectation, we observed less affected juveniles than adults of the same species, however this is partly due to the methodology used. High nitrate tolerance was observed also for juveniles. Additionally, water fleas Daphnia magna were exposed to different nitrate concentrations for 72 hours according to the standard (OECD 202, 2004). A comparison between daphnids and Niphargus sp. adults was possible on a species level: N. timavi and N. stygius adults were more sensitive than D. magna after 72 h, but the sensitivity of N. sphagnicolus was the same. The use of high concentrations of nitrates in the experiments resulted also in the occurrence of microbial growth despite regular changes of test medium.

• Ključne besede: groundwater, Niphargus sp., nitrates, toxicity