Coral Sr/Ca-based sea surface temperature and air temperature variability from the inshore and offshore corals in the Seribu Islands, Indonesia
Introduction
The Seribu islands archipelago (also know as Thousand Islands or Kepulauan Seribu in Indonesian) is an archipelago that extends from the bay of Jakarta, a city of over 10 million inhabitants, to more than 80 km to the northwest in the Java sea. A popular tourist destination, the archipelago includes one of the first officially protected marine areas in Indonesia (Salm et al., 1982). The proximity of the Seribu Islands reef complex to Jakarta metropolitan city induced serious environmental problems, for example many of the inshore reefs, that were still thriving in the 1920s (Umbgrove and Verwey, 1929), are now effectively moribund, consisting of little else than sand, turf algae and the odd massive coral (Rachello-Dolmen and Cleary, 2007, Cleary et al., 2008, de Voogd and Cleary, 2008). Offshore the situation is better, but even here there has been a marked decline in coral cover over the last few decades (Cleary et al., 2008). The Seribu islands are an interesting area to study the influence of large urban populations on reef communities and coastal waters because they are one of the few coral reef systems which are located close to a metropolitan city. Hence, the impact of a large-scale disturbance gradient (e.g. natural factor: El Niño-Southern Oscillation, Monsoon) on coral health in the Jakarta Bay and Seribu islands can be compared with its local-scale disturbance (e.g anthropogenic factors).
A number of recent studies have assessed on-to-offshore variation in environmental conditions and biota of the Seribu islands (Cleary et al., 2006, Van der Meij et al., 2009). In addition to this, museum collections, dating back to the 1920s, were used to compare mollusc and coral composition over an eighty year period (Van der Meij et al., 2009, Van der Meij et al., 2010).
Coral cores have been used to monitor changes in environmental conditions over long periods of time, importantly extending beyond the onset of the instrumental data collection (e.g.; Linsley et al., 2000, Zinke et al., 2004, Ourbak et al., 2006, Cahyarini et al., 2014). In the Seribu islands, coral cores have previously been used to compare fluorescence banding and Pb concentrations. Scoffin et al. (1989) concluded that fluorescence banding was brighter in inshore than in offshore corals. Inoue et al. (2006) presented five years of Pb concentrations which were shown to increase from the off- to inshore corals.
In addition to the above, corals can also be used to monitor variation in temperature.
Coral Sr/Ca is presently the most promising sea surface temperature proxy in paleoclimatology. Several studies have shown that Sr/Ca is influenced only by sea surface temperature (SST; e.g., Zinke et al., 2004, Corrége, 2006, Hetzinger et al., 2006, Cahyarini et al., 2009).
In the present study Sr/Ca ratios in coral cores were determined from massive Porites corals in order to reconstruct variations in SST from an inshore and offshore coral reef. Comparing corals from inshore and offshore environments allows us to ascertain to what extent nearshore conditions influence environmental variables such as temperature. We hypothesise that inshore corals are influenced by air temperature over the adjacent land through air–sea interaction while the offshore corals provide truer records of open sea conditions. In addition to this, we will also assess whether there is evidence of a link between the temperature variations at the Seribu islands and remote climate forcing, i.e. El Niño-Southern Oscillation (ENSO) events and/or South Eastern Indian Ocean (SEIO) SST.
Section snippets
Climate setting at the Seribu islands reef complex
The Seribu islands reef complex (Fig. 1) extends from Jakarta Bay more than 80 km to the northwest in the Java Sea. Natural factors such as the Asian monsoon, ENSO and Indian Ocean Dipole (IOD) influence the waters surrounding the Seribu islands (Haylock and McBride, 2001, Aldrian and Susanto, 2003, Aldrian and Djamil, 2008). During El Nino years, the August SST anomaly shows colder temperature over the Indonesia region including the Seribu Islands than the eastern Pacific Ocean, as exemplified
Material and methods
For this pilot study, historical data including sea surface temperature (SST) and Air temperature (AirT) were used for calibration. SST data was obtained from the Extended Reconstructed Sea Surface Temperature (ERSST) database version 2 (Smith et al., 2008). The ERSST dataset is available for the period 1854 till present. In this study, the average ERSST data (further mentioned as SST) for the coordinates of 105° E–106° E, 5° S–6° S is used. Local measurements of AirT from the Jakarta weather
Monthly and mean annual coral Sr/Ca–SST calibration
Calibration of coral Sr/Ca with SST/AirT has been done based on linear regression between proxy and historical SST datasets. There was a significant linear relationship on monthly time scales between Sr/Ca and SST for the Jukung (r = 0.53, regression slope = − 0.05, p < 0.0001) and Bidadari (r = 0.26, regression slope = − 0.03, p < 0.0001) cores for the 1992–2005 calibration period (see detail calibration in Cahyarini and Zinke, 2009, Cahyarini and Zinke, 2010). The slope of the regression for Jukung (but
Conclusions
This study has shown that the offshore coral is a good proxy of SST while the inshore coral, in contrast, is a better proxy of air temperature (AirT) variability surrounding Jakarta. This indicates that the urbanization and the concomitant air temperature anomalies are a dominant source of temperature anomalies in the inshore coral reefs of the Seribu waters through regional air–sea interactions. Inshore corals from Bidadari and proximate islands thus may provide useful proxy archives to
Acknowledgements
This publication is a result of the Koninklijke Nederlandse Akademie van Wetenschappen (KNAW) Mobility Programme entitled “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” and the International Foundation of Sciences (IFS) research Grant no: A4605-1. We also thank Daniel R.F. Cleary, Miriam Pfeiffer for discussions on this manuscript.
References (38)
- et al.
Monsoon-tropical ocean interaction in a network of coral records spanning the 20th century
Mar. Geol.
(2003) Sea surface temperature and salinity reconstructions from coral geochemical tracers
Palaeogeogr. Palaeoclimatol. Palaeoecol.
(2006)- et al.
New Views of tropical paleoclimates from corals
Quat. Sci. Rev.
(2000) - et al.
Distribution and temporal changes of lead in the surface water in the western pacific and adjacent seas derived from coral skeleton
Environ. Pollut.
(2006) - et al.
Relating coral species traits to environmental conditions in the Jakarta Bay/Pulau Seribu reef system, Indonesia
Estuar. Coast. Shelf Sci.
(2007) - et al.
Decline of the Jakarta Bay molluscan fauna linked to human impact
Mar. Pollut. Bull.
(2009) - et al.
Long-term changes in coral assemblages under natural and anthropogenic stress in Jakarta Bay (1920–2005)
Mar. Pollut. Bull.
(2010) - et al.
ENSO and Indian Ocean subtropical dipole variability is recorded in a coral record off Southwest Madagascar for the period 1659 to 1995
Earth Planet. Sci. Lett.
(2004) - et al.
Seasonal characteristics of the Indian Ocean dipole during the Holocene epoch
Nature
(2007) - et al.
Recent intensification of tropical climate variability in the Indian Ocean
Nature
(2008)
Spatio-temporal climatic change of rainfall in East Java Indonesia
Int. J. Climatol.
Identification of three dominant rainfall regions within Indonesia and their relationship to sea surface temperature
Int. J. Climatol.
Damage and recovery of coral reefs affected by El Niño related seawater warming in the Thousand Islands, Indonesia
Coral Reefs
Geochemical tracer in coral as a sea surface temperature proxy: records from Jukung coral
ITB J.
Calibration of the multicores Sr/Ca records-sea surface temperature: records from Tahiti corals (French Polynesia)
Int. J. Earth Sci.
Twentieth century sea surface temperature and salinity variation at Timor inferred from paired coral δ18O and Sr/Ca measurements
J. Geophys. Res. Ocean
Coral diversity across a disturbance gradient in the Pulau Seribu complex off Jakarta, Indonesia
Biodivers. Conserv.
Relating variation in species composition to environmental variables: a multi-taxon study in an Indonesian coral reef complex
Aquat. Sci.
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