Value of ponds in bomb craters formed during World War II in maintaining biodiversity

With the ongoing loss of aquatic habitats worldwide, small water bodies are becoming increasingly important as substitute habitats for aquatic biota. In this study, we evaluated the diversity of benthic fauna in ponds formed in craters created by bombings during World War II in Poland (Central Europe), as water bodies originating under such circumstances are rarely studied. Macroinvertebrate samples were collected from 62 ponds, and data on macrophyte distribution, water parameters, and the water bodies surface area were recorded. Despite the small size, the ponds were characterized by a high diversity of benthic fauna. In total, invertebrates representing 61 lower taxa (species, genera, and families) were collected. Among the environmental variables examined, only water oxygenation, conductivity, phosphate content, macrophyte coverage, and sunlight exposure affected the structure of the benthic fauna. No correlation was observed between pond size and diversity indices, although a relationship was found between surface area and macroinvertebrate density. The Kruskal–Wallis ANOVA indicated significant differences between ponds with different macrophyte distributions and diversity indices. The Mann–Whitney U test revealed significant differences in faunal diversity between shaded and sunlit ponds. This study demonstrated that individual ponds had a significant influence on regional diversity (γ diversity), emphasizing the importance of pond networks in maintaining biodiversity at the landscape level. Despite the ecological role of bomb crater ponds, they are often omitted from studies on small ponds. Further research is, therefore, essential, especially since small aquatic environments are particularly sensitive to disturbances and may disappear within a short period.