Delayed metamorphosis and increased metal flux from chironomids exposed to contaminated sediment

• Aquatic insects have been regarded as insensitive to metal contamination, but those assessments have been based on short-term toxicity tests disregarding sensitive life-stages, such as metamorphosis. A hampered metamorphosis may also affect terrestrial ecosystems, via reduced insect emergence. It is thus important to perform relevant tests that includes sensitive life-stages, such as metamorphosis, to fully understand the toxic effects on aquatic insects and the potential cascading effects on terrestrial ecosystems. In this study we evaluated the impact of metal contamination on timing and success of adult insect emergence by exposing chironomid (Chironomus riparus) larvae to a gradient of Pb/Zn contaminated sediment. We also investigated sex-differences in accumulation pattern of metals. Fewer adults emerged from treatments with high metal exposure compared to reference treatments and the emergence was also delayed. However, metal contamination mostly affected the survival of insect larvae, and had limited effect on metamorphosis. Males accumulated slightly higher concentrations of Pb than females, but due to their smaller sizes the individual and total flux of Pb, but also Zn, was still higher from females. The total flux of Pb, but not Zn, to terrestrial ecosystems increased with higher sediment exposure. Thus, terrestrial insectivores will be subjected to different pollution regimes depending on sediment contamination patterns, experience reduced food availability and possibly a mismatch between food availability and dietary needs due to delayed emergence.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Environmental Sciences (hsv//eng)

Nyckelord

metals

chironomids

aquatic insects

metamorphosis

subsidy

cross-ecosystem impact

ekotoxikologi

Ecotoxicology

environmental science

miljövetenskap

Publikations- och innehållstyp

vet (ämneskategori)

ovr (ämneskategori)