Geochemical monitoring of coral growth banding in Porites corals as a proxy of anthropogenic induced pollution and environmental modification: case study Kepulauan Seribu - Jakarta Bay, Indonesia
06 / 2007 - 09 / 2009
The Kepulauan Seribu (Thousand Islands) is an archipelago well known for its maritime tourism and its unique position close to Jakarta, a city of over 10 million inhabitants. The Kepulauan Seribu lies at the westernmost extension of the centre of maximum marine benthic biodiversity within the Indo-Malayan region. Elsewhere, very few coral reefs are located close enough to metropolitan cities to study the influence of large urban populations on reef communities and coastal waters..Hence, the impact of a large-scale disturbance gradient (include. surrounding countries) can be compared with local-scale disturbance (Indonesian urban centers) on coral health in the Jakarta Bay and Kepulauan Seribu reef complex off Jakarta, Indonesia. Natural factors such as the Asian monsoon and El Niño-Southern Oscillation (ENSO) influence marine biodiversity off Jakarta bay (Seribu islands waters). These seasonal movements of freshwater due to the monsoonal phenomena control seasonal changes of sea surface temperature (SST) and salinity in the Seribu island waters. During the wet monsoon season, intensive rainfall feeds freshwater runoff into Jakarta bay (Gordon et al., 2004). The prevailing monsoon winds distribute the freshwater plume within Jakarta bay affecting the Seribu reef complex with varying intensity. In addition, El Nino events bring drought and high sea surface temperatures in several locations across the Seribu islands (Brown and Suharsono, 1990; Suharsono, 1998), the mortality of corals increases due to such natural causes (Suharsono, 1998). In combination, natural and anthropogenic influences (increased river runoff, pollution) put high pressure on coral reef biota (Suharsono, 1998) and fishery resources. Recently, a Indonesian-Netherlands programme (2005) on marine biodiversity provided new data on changes in taxon richness, composition and cover in the Kepuaulan Seribu complex. (Cleary et al., 2007) This survey was part of a unique long-term study which started in 1985, repeated every 10 years. Extensive museum collections dating back to 1920´s were combined with the new studies to provide the longest available data base on biodiversity changes ever established. To bring the biodiversity data into a long-term context in terms of environmental pollution and climate change, a large set of coral cores was drilled along an inshore-offshore gradient in the Seribu reef complex. 42 cores are available which cover all aspects of local and large-scale environmental gradients. Former studies on corals from Seribu islands focussed on very short-term windows and did not provide a historical perspective of environmental changes. Here, we can use a unique set of coral core material to answer the question how natural climate change and anthropogenic induced land-use changes and pollution affected the Seribu reef complex during the 20th century. We aim to establish quantitative measures of natural variability before intense industrialisation of Jakarta Bay in the early 20th century and to determine how it compares to the late 20th century. In this truly multidisciplinary study, we will cross traditional boundaries between various scientific disciplines such as biology, geology, metereology and environmental sciences to assess the complex interactions of human activities and natural processes. Such multidisciplinarity is required to provide coherent advise to policy makers for sustainable future planning and management. In light of the most recent catastrophic flooding of Jakarta, knowledge about the impact of severe flooding events on the natural resources within Jakarta Bay can be provided by this study.