|Monitoring the distribution of plastic in an Indonesian mangrove forests|
Raven, O. (2020). Monitoring the distribution of plastic in an Indonesian mangrove forests
. Thesis. NIOZ Royal Netherlands Institute for Sea Research: Yerseke. 19 pp.
The Indonesian island of Java has a problem with a large amount of plastic waste. The plastic waste ends up in rivers and eventually in the sea, where it is harmful to the environment. For example, plastic gets entangled or buried under the sediment, which could cause suffocation of the mangrove tree roots, hampering the growth of mangrove trees. This can make mangrove restoration projects more difficult. In this study the distribution of plastic in a mangrove forest was investigated using quadrats to determine the number of plastic items and the plastic coverage ratio on the forest floor. This was done using images of the quadrats. In addition, the burial depth of plastic was analysed by core samples which were taken in the same place as the quadrats. All of this was done in different sites and different zones of mangrove forests with several explanatory variables clustered on a local scale (Sedimentation and zone), landscape scale (Buildings in 5km from the site, built environment within 5km from site (m2), river mouths in 5km from site and built environment in river basin upstream from site (m2/m2)), and seasonal influence. This study showed that the number of plastic items on the mangrove forest floor depends on the location in the forest (seaside, fringe, or basin) and the sediment type. Further the built environment in river basin upstream from site has an impact on the number of plastic items found on the forest floor. This effect was not found for the plastic coverage ratio and burial depth. This could be caused by plastic on the floor of the mangrove forest is very agile and can be moved by currents and winds and by missing measurements for sedimentation. Explanatory variables on local as on landscape scale show an effect for the number of plastic items. So, the plastic in the mangrove forests probably has a regional source. Awareness of the problems caused by plastic pollution could encourage the society to reduce the plastic pollution in the rivers and costal area to save the environment and the mangrove forests.