To litter or not to litter that is the question, or the impact of tourist litter pollution on the macrofauna

Abstract

Discarded bottles abandoned by tourists in forests pose a considerable threat to invertebrates that has not been adequately researched to date. In order to investigate this matter, empty PET bottles and aluminium cans containing small amounts of 5 qualitatively different beverages they were originally filled with were placed simultaneously in forests. They were subsequently collected, 3 bottles/cans of each type, during three site inspections to analyze mortality of the macrofauna inside them. The composition of macrofauna may be affected by the presence of Anoplotrupes stercorosus, which occasionally feeds on dead animal matter. Therefore, the study consisted of 2 stages, the aim being to identify patterns of invertebrate mortality in bottles when A. Stercorosus presence was limited (stage 1) and not limited (stage 2). The effect of certain beverages on macrofauna mortality was also studied. Stage 2 additionally involved 4 variants of habitat fertility. The most marked differences compared with invertebrate mortality in mineral water bottles (control) were noted for beer cans, which was attributed to the dark insides of the latter. The sequence of appearance of isopods, predators and different developmental stages of dipterans inside the cans indicated the presence of an operational detritus mini ecosystem. Invertebrate mortality in empty bottles originally containing caffeine and a high amount of sugar was also different from the patterns identified in the control bottles (mineral water). This was thought to be related to the luring „power” of sugar. The highest mortality of the macrofauna was recorded in a moderately fertile forest habitat, followed by the most fertile habitat. This was believed to be related to the well-developed vertical structure of the moderately fertile habitat. Altogether, this study shows that litter collecting campaigns in forest and other valuable natural habitats is an aesthetic procedure that also protects the macrofauna of the litter and soil representing a range of diversified trophic preferences.