engleski

Can we replace formalin and still achieve reliable determination of archived macrozoobenthos?

Successful fixation and preservation of ecological samples can be invaluable when studying ecological changes on different time scales, especially when dealing with sediment and/or macrozoobenthos samples, which are considered efficient indicators of habitat quality and ecosystem health in aquatic environments. Therefore, it is very important to find a suitable solution for longer-term storage of samples, i.e., an efficient fixative and/or preservative that does not alter the mechanical (i.e., morphological) integrity of the stored organisms. In this study, we compared the efficacy of five different solutions (glyoxal, 3.6% formaldehyde, neutral buffered formalin, 70% ethanol, 99% ethanol) for preserving key morphological features of macroinvertebrates commonly found in streams (Chironomidae, Baetidae, Ephemeridae, Heptageniidae). Our goal was to contribute to ongoing attempts to find a new "gold standard" fixative/preservative (instead of formalin, which is known to be a carcinogen) that would allow long-term ecological research and reliable morphological identification of stream macroinvertebrates, including specimens from archive samples. Our results show that different preservatives/fixatives have different effects on tissue preservation of different organisms. Moreover, we concluded that there is no unique formalin successor that could serve as a new "gold standard" for the preservation of macroinvertebrate taxa commonly encountered in morphological, and stream ecology studies. The efficiency of different solutions in maintaining the integrity of macroinvertebrate tissues depends on the chemical properties and concentrations of the fixative/preservative, the tissue type, and the size and structure (e.g., extent of chitin coverage) of the organisms studied.

aquatic ecology ; urban streams ; aquatic invertebrates

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