Flow velocities, sea surface elevations, salinity profiles and meteorological data were gathered during three field campaigns in 2006, 20. This study is based on a number of extensive field surveys in combination with numerical modelling. The main objectives of this thesis are to understand the tidal dynamics and circulation patterns at the BCS, to investigate spatio-temporal river plume spreading at the BCS, to identify the relationship between the salinity levels and coastal ecosystem health and to understand intratidal circulation patterns on the BCS coral reefs system. These conditions may affect water quality and imply a number of negative impacts on the BCS coastal ecosystems. Land-use changes of the catchment area of the Berau River lead to increased loads of sediment, nutrients and pollutants in river discharge as a result of mining, logging, and agriculture development. Like many other coastal ecosystems around the world, the BCS is under pressure from human activities.
The area is part of the Coral Triangle in the central Indo-West Pacific and features an extremely high biodiversity. The Berau Continental Shelf (BCS) is located in East Kalimantan, Indonesia.
Our study is the first metagenomic assessment of WIO coral reef microbial diversity which provides a much-needed baseline for the region, and points to a potential area for future research toward establishing indicators of environmental perturbations. Malindi and Mombasa marine parks, the coral reef sites closest to densely populated settlements were significantly enriched with genes for functions suggestive of mitigation of environment perturbations including the capacity to reduce intracellular levels of environmental contaminants and repair of DNA damage. Furthermore, the near-coral seawater and sediment metagenomes had an overrepresentation of COGs for functions related to adaptation to diverse environments. The coral reefs showed variations in the relative abundances of ecologically significant taxa, especially copiotrophic bacteria and coliphages, corresponding to the magnitude of the neighboring human impacts in the respective sites. Over 19,000 species (bacterial, viral and archaeal combined) and 4,500 clusters of orthologous groups of proteins (COGs) were annotated. We compared taxonomic and functional diversity of microbial communities inhabiting near-coral seawater and sediments from Kenyan reefs exposed to varying impacts of human activities. Little is known about coral reef microbial communities of the Western Indian Ocean (WIO). Because environmental changes lead to their compositional and functional shifts, coral reef microbial communities can serve as indicators of ecosystem impacts through development of rapid and inexpensive molecular monitoring tools. A higher coral stress indicator value means a high proportion of injured or algae infested corals, and/or a high soft coral cover, and/or a high proportion of rocky substrate suitable for, but unoccupied by, living corals.Ĭoral reefs face an increased number of environmental threats from anthropomorphic climate change and pollution from agriculture, industries and sewage. Values for the combined coral stress indicator were found to increase in proportion to increasing values of terrigenous sediment loads in both study areas. However, a combined coral stress indicator involving all three factors was shown to have a clear relationship with terrigenous sediment loading and provided a rapid means of field evaluation of the effects of sediment stress on stony corals. Correlations, between each of the above three coral stress response indicators, on the one hand, and quantitative indicators of sediment loading, on the other hand, were not clear. The influence of terrigenous sediment from the Sabaki River appears to be strongest in the Watamu area in the south and in the northern-most part of the Malindi reef area. Decline of this reef had been repeatedly noted during the preceding decade. The relationship between these indicators and the distribution of terrigenous sediment was studied for the Malindi-Watamu fringing reef complex along the Kenyan coast off East Africa during 19.
Indicators of coral decline measured in the present study were: (1) injury to living stony corals (2) soft coral cover and (3) bare rocky substrate suitable for colonization by corals. Sediment discharges from rivers have a negative impact on coral reef ecosystems.
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