Despite high temperature and salinity conditions that challenge reef growth in other
oceans, the Red Sea maintains amongst the most biodiverse and productive coral
reefs worldwide. It is therefore an important region for the exploration of coral reef
functioning, and expected to contribute valuable insights towards the understanding
of coral reefs in challenging environments.
This dissertation assessed the baseline variability of in situ abiotic conditions
(temperature, dissolved oxygen, pH, and total alkalinity, among others) in the central
Red Sea and highlights these environmental regimes in a global context. Further,
focus was directed on biotic factors (biofilm community dynamics, calcification and
bioerosion), which underlie reef growth processes and are crucial for maintaining
coral reef functioning and ecosystem services. Using full-year data from an
environmental cross-shelf gradient, the dynamic interplay of abiotic and biotic
factors was investigated.
In situ observations demonstrate that central Red Sea coral reefs were highly variable
on spatial, seasonal, and diel scales, and exhibited comparably high temperature, high
salinity, and low dissolved oxygen levels, which on the one hand reflect future ocean
predictions. Under these conditions epilithic bacterial and algal assemblages were
mainly driven by variables (i.e., temperature, salinity, dissolved oxygen) which are
predicted to change strongly in the progression of global climate change, implying an
influential bottom up effect on reef-building communities. On the other hand,
measured alkalinity and other carbonate chemistry value were close to the estimates
of preindustrial global ocean surface water and thus in favor of reef growth processes.
Despite this beneficial carbonate chemistry, calcification and carbonate budgets in
the reefs were not higher than in other coral reef regions. In this regard, seasonal
calcification patterns suggest that summer temperatures may be exceeding the
optima of calcifiers. As a possible interpretation of the here observed environmental regimes, it can be concluded that the central Red Sea may be less sensitive to ocean acidification, but is
already impacted by ocean warming. Importantly, this dissertation provides valuable
present-day baseline data of the natural variability of relevant abiotic drivers
together with benthic community and reef growth dynamics. These data will be
important for future comparative studies and efforts to quantify the impact of future
environmental change in the region.
| Identifer | oai:union.ndltd.org:kaust.edu.sa/oai:repository.kaust.edu.sa:10754/612171 |
| Date | 06 1900 |
| Creators | Roik, Anna Krystyna |
| Contributors | Voolstra, Christian R., Biological and Environmental Science and Engineering (BESE) Division, Jones, Burton, Ravasi, Timothy, McCulloch, Malcolm |
| Source Sets | King Abdullah University of Science and Technology |
| Language | English |
| Detected Language | English |
| Type | Dissertation |
| Rights | 2017-06-08, At the time of archiving, the student author of this dissertation opted to temporarily restrict access to it. The full text of this dissertation became available to the public after the expiration of the embargo on 2017-06-08. |
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