Effects of Human Disturbance on the Environment: A Microbial Ecology Perspective

Abstract

The effects of human disturbance are increasing rapidly and can be observed in ecosystems in terms of effects on larger organisms. This thesis analyzes three case studies to explore how human disturbances affect the environment at the microbial scale. The first study examined how land use change affects the structure and diversity of fungal communities in Malaysian tropical forests in Borneo. It was clear that α and β-diversity, as well as community composition differed across different logging histories (unlogged, once-logged and twice-logged), and oil palm plantations. The second study examined how increasing atmospheric CO2 on the ocean impacts the sediment bacterial communities off Vulcano, Italy in the Mediterranean. Bacterial community composition changed with increasing CO2, and bacterial diversity increased with higher CO2. The globally increasing ocean CO2 can be associated with shifts in sediment bacterial community composition, but most of these organisms are resilient. The third study compared the effect of both raw and acid treated (functionalized) multi-walled carbon nanotubes (MWCNTs) on soil bacterial communities, applying different concentrations of MWCNTs (0 µg/g, 50 µg/g, 500 µg/g and 5000 µg/g) to a soil microcosm system. Bacterial diversity was not affected by either type of MWCNT. However, overall soil bacterial community composition for functionalized carbon nanotubes at high concentrations were affected. This last study suggests that fMWCNTs may alter microbial community composition on the timescale of at least weeks to months. In contrast, it appears that raw MWCNTs do not affect soil microbial community composition. These different case studies are examples of the ways in which metagenetic studies can help recognize the impact of human disturbance on the environment, ultimately enabling us to allow effective management decisions in order to protect the environment.