Kunstmatige substraten als standaard-monstermethode voor macrofauna in sloten. Een onderzoek in de Volgermeerpolder

This report, deals with a research about the applicability of artificial substrates as a standard sampling-method for macrofauna. Macrofauna is considered as the macroscopic invertebrate fauna in aquatic ecosystems. The artificial substrates, open steel constructions filled with roofing-tiles, were placed at five sampling-sites at successively greater distances from a dumpsite for waste products in the “Volgermeerpolder”. Between ca. 1960 and 1969 apart from domestic waste also chemical waste was dumped here. This chemical waste was a by-product in the production of pesticides. The poisonous particles also occur in the water and the silt, near the dumping ground. Heavy metals also reach high concentrations near this place. Therefore in this research the influence of these chemicals upon the macrofauna is studied too. It. is a continuation of a former research by Jan van Dijk, Maarten Kramer and Leo Verhagen, who sampled the same sites. The research about the applicability of artificial substrates showed that this method is usable for sampling sessile groups of organisms. The high resemblance of the similarity- and saprobic-indices based on netand artificial substrate-samples makes clear, that sampling with artificial substrates can be suitable for certain purposes. Especially in research, from which a fast elaboration is needed to come to a statement concerning water-quality at a given locality, sampling by means of artificial substrates can be applied. The influence of the chemical dump is visible in very different groups of animals. A strong connection exists between the presence of toxic chemicals and the oxygen uptake mechanism of the found species. Breathing atmospheric oxygen increases in more polluted sites. References cited here indicate, that heavy metals in particular play an important role in this phenomenon.