Community and population characteristics of soil arthropods along a heavy metal gradient in urban brownfields
Creators: name: Wadhwa, Sahil
Publisher: name: No Publisher Supplied
Year: 2017

description: The rapid urban development over the last several decades is one of the main reasons of declining native biodiversity. With increasing urbanization, it is therefore important to include urban areas in biodiversity conservation efforts. While the contribution of managed urban habitats towards biodiversity conservation is recognized, brownfields, a potentially important urban habitat are often ignored in conservation planning. Brownfields are the unmanaged, often polluted (due to former industrial use), and abandoned habitats with spontaneously grown vegetation. Studies have shown that brownfields can function as reservoirs of biodiversity in urban areas. However, in order to maintain and increase the diversity in these habitats and in urban areas overall, it is crucial to understand how factors such as metal contamination shape biodiversity in brownfields. The objective of this thesis is to examine the community and population characteristics of soil arthropods in relation to metal contamination in urban brownfields. To accomplish this objective, I investigated effects of metal contamination on the: (1) diversity of epigeic invertebrate community in an urban brownfield, (2) abundance patterns and composition of terrestrial isopods assemblages in an urban brownfield, (3) fluctuating asymmetry in the populations of terrestrial isopod and hardwood trees in an urban brownfield, and (4) growth and metal body burdens of a terrestrial isopod, Philoscia muscorum. The results showed that the overall diversity of soil invertebrate assemblage was not negatively affected by soil metal contamination. However, negative effects of metal contamination were observed both on the community and on most of the isopod species (3 out of 4) found at the brownfield site. The results suggest that most of the soil invertebrate taxa might have developed adaptive tolerance mechanisms to survive at metal contaminated sites which imply that metal contamination at the brownfield site might not be limiting the food availability for animals on higher trophic levels. On the other hand, these results also highlight the higher sensitivity of isopods to metal contamination which might result from greater accumulation of metals in isopods than other soil invertebrates. Interestingly, differences in sensitivity to metal contamination were also found between different isopod species at the brownfield site. Based on results of this study, it is recommended that isopods at family level (Oniscidae) and species level (P. muscorum) can be used as a bio-indicator of metal pollution in terrestrial ecosystems. The results of litter feeding study showed a significant reduction in growth of isopod P. muscorum following exposure to metal contaminated food and soil. Moreover, weight change in isopods was found to be more negatively affected by contamination of soil than contamination of the leaf litter. These results are significant for showing the importance of soil as a route of metal exposure in isopods. Overall, results show that despite the metal pollution, brownfields can function as an important habitat for soil arthropods and therefore can contribute to urban biodiversity conservation. The results of this study can be used for designing restoration and management plans for brownfields.