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Coral Sr/Ca-based sea surface temperature and air temperature variability from the inshore and offshore corals in the Seribu Islands, Indonesia
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Data
July 2016
... Temperature proxies from modern coral used in this study are from Timor Island [12], Seribu islands [13], and Enggano islands [2] (Figure 2). Statistical analysis of time series data is implemented on the proxies. ...
... The modern coral from the Sunda Strait [2] and Mentawai [10] records SST variability in this region, which shows clearly seasonal variability of SST. The SST trend shows increasing seasonal temperature of about 0.5 to 1.5 o C recorded from the modern coral from Enggano [2], Seribu [13] and Timor waters [12] (Figure 2). ...
... Temperature proxy records from modern coral (Enggano [2], Timor [12], Seribu [13]) and sub fossil coral (Mentawai [10], Lampung Bay-Sunda Strait [2]) covering Medieval period. The red line is linear trend. ...
A period that lasted from 900-1300 AD has been known as the Medieval Climate Anomaly. This period has been indicated as the warming period of the earth’s temperature. However, this warming phenomenon is still the subject of debate today, whether global or regional warming. Several studies concluded that the Medieval warm period is a global phenomenon and an important warm period, although external forcing is mainly similar to the present day. Several climate archives from Indonesia i.e. lake sediment, marine sediment and speleothem show a warming trend during this period. In this study, the seasonal warming trend during the Medieval climate is resolved from Porites coral from Lampung Bay, Indonesia. However, the seasonal temperature magnitude during the Medieval period is lower than today. This study confirms the coral medieval climate records from Mentawai islands. The result suggests that a warming trend occurred in Indonesia during the Medieval climate anomaly.
... The climate in Kepulauan Seribu is tropical with relative humidity of 80-90% (Tomascik et al. 1997). The maximum sea surface temperature (SST) is observed in April (29.8 °C) and minimum in January (28.6 °C) (Cahyarini et al. 2016). Surface salinity in the Java Sea (30-34‰) is well below normal open ocean levels, reaching as low as 22‰ in the vicinity of some of the larger river mouths. ...
... δ 13 C and δ 18 O values are reported in ‰ versus the Vienna PeeDee belemnite (V-PDB). A core of 68 cm length was drilled in September 2005 from a massive Porites coral in the Kepulauan Seribu complex, inshore of Bidadari Island at site 6°01′55″S, 106°44′47″E ( Fig. 1) from 3 m water depth (Cahyarini et al. 2016). δ 13 C and δ 18 O values were measured at the Stable Isotope Laboratory, Vrije University, Amsterdam. ...
... Carbon isotope data from a Porites coral from Bidadari Island (Fig. 1) in the Java Sea, is on average more depleted compared to Porites corals from the Seychelles and Chagos both of which are located within the IPWP (Fig. 8) (Pfeiffer et al. 2004;Pfeiffer and Dullo 2006;Cahyarini et al. 2016). It is unlikely that this difference is solely due to kinetic related offsets, since all three coral colonies show similar growth rates (Pfeiffer et al. 2004;Pfeiffer and Dullo 2006;Cahyarini et al. 2016). ...
Kepulauan Seribu is an isolated patch reef complex situated in the Java Sea (Indonesia) and is a typical example for a humid, equatorial carbonate system. We investigate the mineralogical and isotopic fingerprint of Panggang, one of the reef platforms of Kepulauan Seribu, to evaluate differences to other carbonate systems, using isotope in combination with XRD and SEM analysis. A characteristic property of shallow water (< 20 m) sediments from Kepulauan Seribu is their increased LMC content (~ 10%) derived from some genera of rotaliid foraminifers and bivalves. The relative abundance of these faunal elements in shallow waters might be related to at least temporary turbid conditions caused by sediment-laden river runoff. This influence is also evidenced by the presence of low amounts of siliciclastic minerals below the regional wave base. Kepulauan Seribu carbonates are characterized by very low δ13C and δ18O values. This is related to the isotopically depleted riverine input. The δ13CDIC in riverine water is reduced by the contribution of 12C from riverside mangroves. Deep atmospheric convection and intensive rains contribute 18O-depleted freshwater in the river catchments, finally reducing salinity in the Java Sea. The depleted δ13C signature in carbonates is further enhanced by the lack of green algae and inorganic carbonates and abundance of coral debris. Low δ18O values in carbonates are favored by the high water temperatures in the equatorial setting. Since equatorial carbonates in SE Asia, including the Java Sea, are typically influenced by high turbidity and/or river runoff, the observed distinctively low isotope values likely are characteristic for equatorial carbonate systems in the region.
... Geochemical proxies i.e Sr/Ca ad δ 18 O in corals have been used for reconstructing past climate variability. Coral Sr/Ca can provide information on past SST [5,6] and paired Sr/Ca and δ 18 O may be used to reconstruct variations in the precipitation balance (salinity) at monthly resolution [5,7]. In this paper, several results of the study of climate reconstruction using geochemical proxies recorded in coral from Indonesian waters will be summarized and evaluated. ...
... Coral Sr/Ca from the inshore and offshore Seribu islands waters is used to reconstruct sea surface temperature (SST) and air temperature (Figure 1) [6]. This study shows that the offshore coral shows sea surface temperature proxy better than the inshore coral. ...
... Coral Sr/Ca records from Jukung and Bidadari island represent offshore and inshore coral respectively from the Seribu islands complex (figure modified from [6]). B. Paired coral Sr/Ca and δ 18 O from Timor coral (figure modified from [8]). ...
Indonesia is located in the prominent site to study climate variability as it lies between Pacific and Indian Ocean. It has consequences to the regional climate in Indonesia that its climate variability is influenced by the climate events in the Pacific oceans (e.g. ENSO) and in the Indian ocean (e.g. IOD), and monsoon as well as Indonesian Throughflow (ITF). Northwestern monsoon causes rainfall in the region of Indonesia, while reversely Southwestern monsoon causes dry season around Indonesia. The ENSO warm phase called El Nino causes several droughts in Indonesian region, reversely the La Nina causes flooding in some regions in Indonesia. However, the impact of ENSO in Indonesia is different from one place to the others. Having better understanding on the climate phenomenon and its impact to the region requires long time series climate data. Paleoclimate study which provides climate data back into hundreds to thousands even to million years overcome this requirement. Coral Sr/Ca can provide information on past sea surface temperature (SST) and paired Sr/Ca and δ¹⁸O may be used to reconstruct variations in the precipitation balance (salinity) at monthly to annual interannual resolution. Several climate studies based on coral geochemical records in Indonesia show that coral Sr/Ca and δ¹⁸O from Indonesian records SST and salinity respectively. Coral Sr/Ca from inshore Seribu islands complex shows more air temperature rather than SST. Modern coral from Timor shows the impact of ENSO and IOD to the saliniy and SST is different at Timor sea. This result should be taken into account when interpreting Paleoclimate records over Indonesia. Timor coral also shows more pronounced low frequency SST variability compared to the SST reanalysis (model). The longer data of low frequency variability will improve the understanding of warming trend in this climatically important region.
... Sampel Pulau Jukung digunakan sampel dari Cahyarini et al. (2016). Prosedur preparasi geokimia Sr/Ca sampel karang dari Pulau Jukung mengikuti prosedur yang dilakukan oleh Cahyarini et al. (2016), preparasi sampel karang dilakukan dengan melarutkan sampel tertimbang dengan 1 mL asam nitat 2% (v/v). ...
... Sampel Pulau Jukung digunakan sampel dari Cahyarini et al. (2016). Prosedur preparasi geokimia Sr/Ca sampel karang dari Pulau Jukung mengikuti prosedur yang dilakukan oleh Cahyarini et al. (2016), preparasi sampel karang dilakukan dengan melarutkan sampel tertimbang dengan 1 mL asam nitat 2% (v/v). Sampel yang telah didestruksi diambil dengan volume tertentu (tergantung pada berat bubuk karang) kemudian diencerkan dengan asam nitat 2% (v/v) sehingga pada volume 5 mL untuk mendapatkan 8 mg/L Ca. ...
... Variasi bulanan konsentrasi Sr/Ca sampel karang Pulau Jukung hasil analisis SSA-nyala berkisar antara 1,005 -10,914 mmol/mol, dengan rata-rata 7,708 mmol/mol. Hasil analisis sampel karang Pulau Jukung dengan ICP rata-rata 8,59 mmol/mol dengan kisaran 8,45 -8,72 mmol/mol (Cahyarini et al.,2016). Gambar 3 menunjukkan variasi bulanan konsentrasi Sr/Ca pada sampel karang Pulau Jukung hasil SSA-nyala. ...
p> The ratio of Sr/Ca concentration in coral is usually used as paleothermometer. Inductively Coupled Plasma (ICP) is an instrument, which is often used to analyze Sr/Ca concentration in Porites sp. The method is very sensitive and requires small amount of sample. However, the availability of this instrument is very limited. To deal with it, Flame Atomic Adsorption Spectrophotometer (FAAS) is an alternative in order to analyze the concentration of various elements include Sr and Ca. The aim of this study was to evaluate the result of the analysis methods of strontium and calcium concentration in coral using FAAS and compared to ICP results. Sample of Porites coral was taken from Ambon Bay and Jukung Island. The strontium and calcium concentration were analyzed using Flame Atomic Adsorption Spectrophotometer (FAAS). The results showed that the average of ratio Sr/Ca in coral from Ambon Bay and Jukung Island were 8.71 and 7.708 mmol/mol. The monthly variation of ratio Sr/Ca in coral from Ambon Bay were 6.28 - 10.24 mmol/mol, while in coral from Jukung Island were 1.005 - 10.914 mmol/mol. Result of FAAS analysis was too broad in range compared to ICP , ie 8.462 - 8.807 dan 8.45 – 8.7 mmol/mol. The range was estimated due to the occurrence of strontium and calcium ionization reaction in flame of FAAS .
Keywords : FAAS, coral, ratio Sr/Ca</em
... Sampel Pulau Jukung digunakan sampel dari Cahyarini et al. (2016). Prosedur preparasi geokimia Sr/Ca sampel karang dari Pulau Jukung mengikuti prosedur yang dilakukan oleh Cahyarini et al., pada tahun 2016. ...
... Variasi bulanan konsentrasi Sr/Ca sampel karang Pulau Jukung hasil analisis SSA-nyala berkisar antara 1,005 -10,914 mmol/mol, dengan rata-rata 7,708 mmol/mol. Hasil analisis sampel karang Pulau Jukung dengan ICP rata-rata 8,59 mmol/mol dengan kisaran 8,45 -8,72 mmol/mol (Cahyarini et al.,2016). Gambar 3 menunjukkan variasi bulanan konsentrasi Sr/Ca pada sampel karang Pulau Jukung hasil SSA-nyala. ...
... Gambar 3 menunjukkan variasi bulanan konsentrasi Sr/Ca pada sampel karang Pulau Jukung hasil SSA-nyala. Hasil analisis SSA-nyala dibandingkan dengan hasil ICP dari Cahyarini et al. (2016) untuk sampel karang dari Pulau Jukung, terlihat bahwa rata-rata konsentrasi Sr/Ca hasil SSAnyala sangat rendah (Gambar 3). Dengan nilai terendah 1,005 mmol/mol, jauh lebih rendah dari nilai terendah konsentrasi Sr/Ca hasil ICP yaitu 8.45 mmol/mol (Gambar 3). ...
p> The ratio of Sr/Ca concentration in coral is usually used as paleothermometer. Inductively Coupled Plasma (ICP) is an instrument, which is often used to analyze Sr/Ca concentration in Porites sp. The method is very sensitive and requires small amount of sample. However, the availability of this instrument is very limited. To deal with it, Flame Atomic Adsorption Spectrophotometer (FAAS) is an alternative in order to analyze the concentration of various elements include Sr and Ca. The aim of this study was to evaluate the result of the analysis methods of strontium and calcium concentration in coral using FAAS and compared to ICP results. Sample of Porites coral was taken from Ambon Bay and Jukung Island. The strontium and calcium concentration were analyzed using Flame Atomic Adsorption Spectrophotometer (FAAS). The results showed that the average of ratio Sr/Ca in coral from Ambon Bay and Jukung Island were 8.71 and 7.708 mmol/mol. The monthly variation of ratio Sr/Ca in coral from Ambon Bay were 6.28 - 10.24 mmol/mol, while in coral from Jukung Island were 1.005 - 10.914 mmol/mol. Result of FAAS analysis was too broad in range compared to ICP , ie 8.462 - 8.807 dan 8.45 – 8.7 mmol/mol. The range was estimated due to the occurrence of strontium and calcium ionization reaction in flame of FAAS .
Keywords : FAAS, coral, ratio Sr/Ca</em
... Bùi Tá Long 1,* , Nguyễn Lan Anh 2 , Cao Thị Bé Oanh 3 ...
... Nước thải từ quá trình làm nguội thiết bị của nhà máy nhiệt điện có lưu lượng lớn, loại nước thải này ít bị ô nhiễm nhưng làm thay đổi nồng độ các chất dinh dưỡng cũng như các chất hòa tan dẫn đến thay đổi môi trường sống của các chất dinh dưỡng cũng như các chất hòa tan dẫn đến thay đổi môi trường sống của các sinh vật dưới nước. Đặc biệt sự thay đổi nhiệt độ trong nước có ý nghĩa rất lớn đối với ngưỡng nhiệt của sinh vật, mức độ lan truyền và khuếch tán nhiệt ảnh hưởng trực tiếp đến hệ sinh thái trong môi trường nước [1][2][3][4][5] . Ngoài ra, nước làm mát còn ảnh hưởng đến vị trí hút nước làm mát của nhà máy nhiệt điện. ...
Thermal energy accounts for more than 50% of the country's total power supply system and plays a particularly important role in the national power supply system. However, the process of cooling the turbine systems of plants and the discharge of used water after cooling are the reasons for the large impact on the aquatic environment and ecosystem. Therefore, it is necessary to calculate the distribution and dispersion of heat in coastal areas removed by thermal power plants. According to the project, the drain source was built near the cooling water intake, so it can affect the source of cooling water. The investor was also considering the construction of a dam to reduce the impact on the supply of cooling water. Both of these options should be considered and analyzed.
Therefore, the research team applied a modeling approach to calculate and evaluate the effect of heat propagation in two scenarios. MIKE21, 3 FM instruments combined with meteorological - oceanographic data. The results showed that the source of discharge affected the inlet position in the station area, and during the construction of the dam, the degree of influence of the source of discharge on the source of cooling water intake of the Binh Dinh power plant was significantly reduced. Before starting the model, the calibration and verification steps are performed, which give satisfactory reliability.
... Corals are susceptible to aquatic environmental changes including the influence of global warming (Brenner et al., 2017;Cahyarini et al., 2016;Chen et al., 2013;Wilkinson and Wilkinson, 1996), ocean acidification (McCulloch et al., 2012;Wei et al., 2009), and human activities (Krishnakumar et al., 2015;Seemann et al., 2014;Wolanski et al., 2004) around the world. Detailed study of PAH compounds in the surface sediments and water was widely reported in and around the world (Ramzi et al., 2017;Perez-Fernandez et al., 2015;Masood et al., 2016;Jaward et al., 2012). ...
The study aims to investigate the source and concentration of PAH fractions in the reef sediments of the Vembar group of Islands, Gulf of Mannar, India. The concentration of PAHs ranged from 0.36 to 15.98 ng/g. The reef environment was less contaminated with low-molecular-weight PAH fractions. The accumulation of the LMW-PAH fraction was very less, whereas the HMW fraction was derived from pyrolytic sources. The level of low and high molecular weight PAHs was lower than the level of Effective Range Median (ERM) and Effective Range Low (ERL).The calculated total TEQ value ranged from ND to 10.24 ng/g in the reef sediments.
... Historical SST observations from the International Ocean-Atmosphere Dataset are the basis for ERSST5 49 , which has a 5°grid resolution and extends back until 1880. ERSST5 data can be compared with the modern coral Sr/Ca record over its entire time period and is routinely used to calibrate and validate coral Sr/Ca records 35,36,38,46,64 . Meanwhile OISSTv2 AVHRR 66 is only back until 1981 November. ...
We present two 40 year records of monthly coral Sr/Ca ratios from the eastern pole of the Indian Ocean Dipole. A modern coral covers the period from 1968 to 2007. A sub-fossil coral derives from the medieval climate anomaly (MCA) and spans 1100–1140 ad. The modern coral records SST variability in the eastern pole of the Indian Ocean Dipole. A strong correlation is also found between coral Sr/Ca and the IOD index. The correlation with ENSO is asymmetric: the coral shows a moderate correlation with El Niño and a weak correlation with La Niña. The modern coral shows large interannual variability. Extreme IOD events cause cooling > 3 °C (1994, 1997) or ~ 2 °C (2006). In total, the modern coral indicates 32 warm/cool events, with 16 cool and 16 warm events. The MCA coral shows 24 warm/cool events, with 14 cool and 10 warm events. Only one cool event could be comparable to the positive Indian Ocean Dipole in 2006. The seasonal cycle of the MCA coral is reduced (< 50% of to the modern) and the skewness of the Sr/Ca data is lower. This suggests a deeper thermocline in the eastern Indian Ocean associated with a La Niña-like mean state in the Indo-Pacific during the MCA.
... Climate studies from the past would consider the relation of tectonic in Indonesia. At present, the regional climate in Indonesia is influenced by monsoon [1,2], Indonesian Throughflow (ITF) [3,4], and global climate phenomena, e.g., Indian Ocean Dipole (IOD), El-Niño Southern Oscillation (ENSO) [5,6,1]. The Indonesian throughflow is an important element in circulating water mass, bringing water mass from the Pacific Ocean to the Indian Ocean, followed by distributing heat through the Indonesian archipelago [7,8]. ...
Pliocene climate is known as global cooling. However, some study was showing a warm condition during Pliocene. During Pliocene in the tropics, the warm condition mechanisms are still in debate, whether it occurs due to the permanent El Niño or not. Indonesia is the prominent site to study climate from past to present. Several Pliocene climate studies have resulted from records surrounding Indonesia, but not many were found from inside the Indonesian sea. Pliocene records based on Pollen analysis content in Sajau Formation, Northeast Kalimantan, shows that the presence convinces the warm wet climate condition during the late Pliocene of arboreal pollen domination. However, the causing mechanism of warm wet Pliocene climate has remained a question.
... The environmental gradient along the Seribu Islands also predisposes the ratio of Sr/Ca in the coral core that is applied as a proxy for predicting sea surface temperature in the past. Cahyarini et al. [13] can evidence that the coral core derived from Jakarta Bay is highly influenced by air temperature and also urbanization, while the coral core derived from offshore of Jakarta Bay is mainly affected by sea surface temperature. In addition, during onset El Nino phase in past years (exemplified in 2015), the coral core of inshore signifies a warming condition, while the coral core of offshore indicates an opposite condition. ...
This research aimed to analyze the sustainability of fisheries in the bay based on ecological footprint (EF) and bio-capacity (BC). The used methods were ecological footprint and biocapacity approaches based on primary production requirement (PPR). Data were derived by surveying main caught fish of small fishermen as a main basis of calculation and the trophic levels were determined by fish base data. The calculation of BC also followed the ecological footprint calculation pattern where its estimation was according to the water types. Results of this research exhibit that all water system types possess the value of EF is higher than the EC value. The average values of EF in tropical shelves (TS) and non-tropical shelves (non-TS), and C&C are 64708 km 2 , 6474 km 2 , and 8148 km 2 , respectively. Whilst, the value of BC is around 2707 km 2 or only about 30% from all total waters of Jakarta Bay that is able to support fishing activities. Furthermore, the values of EF per-capita for TS and non-TS, C&CS, and BC, are 6.04 km 2 /fisherman, 0.71 km 2 /fisherman, 0.42 km 2 /fisherman, and 0,21 km 2 /fisherman, respectively. These counting results signify that the values of ecological footprint (EF) are higher than the values of bio-capacity (BC). This result infers that fishing sustainability in Jakarta Bay has delivered a heavy burden.
... And (ii), climate conditions change, e.g., EI-Niño-Southern Oscillations [26], Monsoons or hurricanes. These meteorological factors may impact the harvesting effort [27]. In fact, Robert et al. [28] stated that environmental fluctuation can be classified into two groups: biological fluctuation (e.g., variations of fish trading markets) and physical fluctuation (e.g., storms, oceanic meteorological factors). ...
With the increasing demand for aquatic products all over the world, exploring the interactions between inshore and offshore fisheries is one of the meaningful issues to help boost yield and meet immediate protein needs. However, pollution and environmental fluctuations (fishery trading market, ocean meteorological factors) may seriously affect the optimal harvesting strategy of the interaction between inshore and offshore components of the fishery. In response to this problem, we present a stochastic inshore–offshore fishery model in a polluted environment, which incorporates harvesting efforts subjected to Lévy jumps and environmental toxicant influence. By virtue of the ergodic methods, the optimal harvesting effort and maximum expectation of sustainable yields are established. Using the hairtail fisheries in the East China Sea as a case study, numerical simulations are carried out to support the theoretical results. These results show that the diffusion between inshore and offshore fisheries, Lévy jumps noise and environmental toxicant input may significantly affect the optimal harvesting strategy, which can provide suggestions for effective measures to increase the aquatic products and guide harmonious development of inshore and offshore aquaculture.
... Studies of modern carbonate systems in Kepulauan Seribu typically focus on their biota and ecology (Umbgrove, 1947;Hoeksema, 1991;Rachello-Dolmen & Cleary, 2007;De Voogd & Cleary, 2008;Farhan & Lim, 2011;Toruan et al., 2013;Cleary et al., 2014;Cahyarini et al., 2016), with only a few focusing on carbonate sedimentology (Scrutton 1976a, b;Park et al., 1992;Jordan et al., 1993). Major carbonate facies zones in Kepulauan Seribu were mapped based on grab and dive samples by Scrutton (1976a, b) and Jordan et al. (1993). ...
Quantitative facies models from modern carbonate are essential for the interpretation of their fossil counterparts. The isolated carbonate platforms of the Kepulauan Seribu archipelago has many atoll‐like islands with reef belts exposed to bidirectional monsoon winds. Statistical analysis based on texture and composition reveal that there are four sedimentary facies; coral grainstone, coral packstone/grainstone, coral‐mollusc packstone, and mollusc wackestone. The occurrence of mollusc wackestone in the lagoon is controlled by water depth, while the sand apron and reef front do not show significant facies separation with water depth. The co‐occurrence of these different facies in the same depth window is contrary to the common thought that changes in bathymetry should be reflected in facies changes. The studied reef systems therefore show aspects of random and ordered facies distribution with respect to water depth. A satellite derived environmental facies map generated by an image analysis algorithm indicates that environmental facies distribution is mainly controlled by water depth, density of sea grass cover and coral abundance. The sand apron can be subdivided into three environmental facies with no, sparse and dense sea grass cover. The deeper water zone can be separated into shallow and deep subtidal parts of lagoons and platform margins. In the lagoon, satellite derived environmental facies directly correlated with sedimentary facies. No direct correlation of environmental facies to sedimentary facies was possible in the sand apron due to the heterogeneity and complexity of the environment. However, the mean sediment grain size is significantly smaller in areas of the sand apron colonised by dense sea grass. This study aims to contribute towards a better understanding of modern equatorial Southeast Asian carbonate systems, delineate modern carbonate facies based on sediment texture and composition with the aid of multivariate statistical analysis combined with statistic based satellite mapping, and give insights regarding the correlation between depositional facies and water depth.
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... The environmental gradient along the Seribu Islands also affects the Sr/Ca ratio in coral cores, used as a proxy for the estimation of past sea surface temperatures. Cahyarini et al. (2016) could show that a coral core obtained in JB was more affected by air temperature and thus urbanization while a core obtained from further offshore was affected more by sea surface temperature. In addition, during the El Niño onset phase in previous years (exemplified by 2015), the inshore core indicated warming while the offshore core indicated cooling. ...
... The uncertainty of the chronology development based on the anchor point method is about 1-2 months in any given year. The result of the chronology development based on Sr/Ca measurements is result in 1968 to 2005 time window (see [16]). ...
Sr/Ca has been analyzed from coral core from the Seribu Islands reef complex i.e Jukung Island. SST from ERSST dataset and air temperature measured at Jakarta is used for Sr/Ca calibration. The results show that Jukung Island coral Sr/Ca correlates better with SST than with air temperature. A comparison between the Sr/Ca records with the Nino 3.4 index shows that Jukung coral sites indicate warming sea surface temperatures during the beginning of El Nino events followed by cooling temperatures at the end of El Nino years.
Jakarta, the biggest city in Indonesia, has one district that consists of hundreds of islands that face severe climate hazards called the Seribu Islands complex. This study explores the evidence of local climate trends, the potential impact, and its policy intervention on Seribu Islands, which are classified as small island states and widely recognized as being especially at risk from climate change, threatening their economic and social growth. Long-term in-situ climate data, satellite data, interviews with local stakeholders, and literature reviews were utilized to conduct an exploratory descriptive analysis. The result revealed that Seribu Island experienced a 2.2°C increase in minimum temperature from 1980 until 2021, 3.5-fold of the frequency of extreme temperature and precipitation, 4.17 mm/year of sea level rise, and 10.8 ha land expansion in the densest island. Moreover, about 67% of the inhabitant’s islands were occupied by built-up areas that cover more than 50% of the region. Further, under the worst-case SLR scenario, about 58.4% of the area will be affected, and about 29 islands will disappear. This evidence was also reinforced by every single local respondent’s viewpoint who felt that climate change is occurring in the region. Even though the region faces a severe threat of climate change, the issue of climate change adaptation has not been mainstreamed yet into their local policy. Therefore, the urgency of a real-time climate ground station, a real-time early warning system, and establishing a Regional Disaster Management Agency (BPBD) at the district level have yet to be addressed. Furthermore, the knowledge gained from such case studies is outlined, along with some scientific evidence that may assist small island states in better fostering the opportunities provided by climate change adaptation.
The concentration of metals in coral represents environmental changes, monsoonal variation, and human disturbance. Metals in coral were used as a proxy to evaluate the response of coastal areas to climatic and human stresses. In this study, several metals including lead (Pb), cadmium (Cd), chromium (Cr) and zinc (Zn) in Porites coral taken from Ambon Bay, Ambon Island, Indonesia, were investigated. The history of metals transient in the most populated island in Maluku Province is documented here from measurements of metals concentration from monthly-banded coral that grew in coastal seawater from 2001 to 2009. The concentration of heavy metals in coral samples was measured using Flame Atomic Adsorption Spectrophotometry (FAAS) method. The results showed metals bioaccumulation (average ± STD) were following decreasing order: Pb (0.96 ± 1.58 μg/g) > Cr (0.15 ± 0.34 μg/g)> Zn (0.11 ± 0.26 μg/g) > Cd (0.007 ± 0.016 μg/g). Moreover, all metals content in the coral showed a remarkable rose from 2001 to 2009 and showed relatively high concentrations during the southeast monsoon for Pb and Cd. Based on the statistical analysis, all metals in Ambon Bay coral were impacted by terrestrial input. In addition, Pb and Cd were also impacted by natural processes that may be associated with their biogeochemical cycle and monsoonal variation.
The Indonesian Throughflow (ITF) plays an important role in the heat flux and water budget between the Pacific and Indian oceans and may modulate climate variability. During the boreal winter monsoon, low-salinity, buoyant water carried from the Java Sea to the Southern Makassar Strait retards the sea-surface transport of the ITF, which may affect the Asian monsoon and climate change. However, observation records are inadequate to elucidate the marine environment around the Indonesian Seas. We analyzed coral Sr/Ca and δ¹⁸O from the Seribu Islands, Java Sea, and reconstructed sea-surface temperature (SST) and sea-surface salinity (SSS) for 1931–2002. The SST data indicate abrupt warming in the mid-1950s and, almost simultaneously, a rapid SSS shift to saline conditions. The relationships between SST around the Seribu Islands and climate variability in the Pacific and Indian oceans have changed after this abrupt warming events. Before the mid-1950s, during September to November, SST varied with the Indian Ocean Dipole, whereas El Niño–Southern Oscillation also affected SST variation after the mid-1950s. This abrupt change seems to be related to a regime shift in the tropical Pacific and Indian oceans, but there are no clear changes corresponding to other regime shifts such as that of 1970s. SSS variation exhibits no relationship with climatic factors, indicating that the dominant controlling factors of SST and SSS should be considered separately. Marine conditions in the Java Sea that affect the ITF show unique behavior, and further local studies in the Indonesian Seas are crucial to understand ITF behavior.
Changing in the concentrations of trace metals in coastal seawater is in parallel with variations of human activities and geochemical processes. Coral skeleton is an excellent archive of metal proxies to monitor water quality as the trace metals incorporate to the skeleton. To study the response of trace metals in coastal seawater to human activities, the coral skeleton of Porites lutea (KR1 and KR2) from Rote Island, Kupang, East Nusa Tenggara, one of the passageways of Indonesian Throughflow (ITF) were used. Corals were drilled vertically using pneumatic tool with diameter 5 cm. The core was cut into 4 mm thick slabs, rinsed with aqua-bidest in an ultrasonic bath, and oven-dried. Sample were then x-rayed using digital radiography to determine the age and annual banding. Sub-samples were collected from each of annual banding using a hand-held drill. The powder of sub-samples were digested with acid and Milli-Q water and analyzed with Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES) for determining of anthropogenic trace metals Cu, Pb, Zn, As, Cd and Cr. Contamination factor was used to assess the pollution degree of the coral. Based on the x-ray radiography, the linear extension rates of KR1 and KR2 are decrease from past 20 years with the average are 1.7 cm/year and 1.4 cm/year, respectively. The average of concentrations of trace metals in KR1 and KR2 followed the order of Cu>Cd>Zn>Cr>Pb>As, and their vertical profiles are slightly increase in the past-20 years. Moreover, the average of concentration all trace metals in KR2 are a bit higher than KR1 which maybe the KR2 is closed to the mainland compare to the KR1. The contamination factors of trace metals are in the level of non-pollution to moderate pollution.
Climate phenomena which is happened in the Pacific and Indian oceans i.e. El Niño Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) influence Indonesian climate. To understand behaviour of climate phenomena and its impact to Indonesian climate it is required paleoclimate data which provide long time series climate data back to hundred till thousands year. Sea surface temperature (SST) is one of important climate parameter. Coral Sr/Ca is convinced as coral paleo-thermometer. In this study, the available coral Sr/Ca is used to reconstruct past SST variability (Coral SST). Univariate linear regression between coral Sr/Ca and SST is used to reconstruct past SST variability. To understand how the climate phenomena influence the SST variability, the coral Sr/Ca is correlated with the Nino 3.4 and IOD indices. The result shows that the influence of IOD and ENSO is difference between sites. At Seribu island coral SST shows that SST is influenced by IOD rather than ENSO, while from Timor coral SST shows that Indian Ocean Dipole (IOD) and ENSO influences SST.
Kepulauan Seribu is a group of islands located in the north of Jakarta. which consist of several sensitive areas such as National Marine Park. settlement. coral reefs. fisheries. and tourism areas. The activities of oil & gas industries and shipping lanes in Kepulauan Seribu could potentially lead to oil spill pollution to waters and coast of Kepulauan Seribu which causing damage to sensitive areas. Past incidents of oil spills in Kepulauan Seribu has causing damages to fisheries. corals reef. and tourism activities. Therefore. appropriate oil spill preparedness and response are required since they are they are regulated by government and are important measures to minimize the negative impacts of an oil spill.
Very few coral reefs are located close enough to metropolitan cities to study the influence of large urban populations on reef communities. Here, we compare the impact of a large-scale disturbance gradient with local-scale disturbance on coral richness, cover, and composition in the Jakarta Bay and Pulau Seribu reef complex off Jakarta, Indonesia. We found no effect of local land-use type of coral reef islands on richness, composition or cover, nor did taxon richness differ among zones at the large-scale. There was, however, a pronounced difference in composition and coral cover among zones. Cover was very low and composition differed markedly in the near-shore zone 1 (Jakarta Bay) where human-induced disturbance is most intense. Cover was highest in the outlying reefs of zone 3. The highly perturbed zone 1 reefs were, furthermore, distinguished by the virtual absence of otherwise abundant coral taxa such as Acropora hyacinthus and Porites rus and the prevalence of taxa such as Oulastrea crispata and Favia maxima. Almost 60% of the spatial variation in composition was related to variation in shelf depth and island size. The importance of shelf depth was related to the prevalence of a strong environmental gradient in reef depth, pollution, and mechanical reef disturbance and salinity from Jakarta Bay to the outlying reefs. Although there was a significant univariate relationship between spatial variation in composition and distance, this did not enter into the multivariate model, except when presence-absence data was used, indicating that environmental processes are the primary structuring forces in determining local coral assemblage composition across the Pulau Seribu complex.
Sr/Ca has been analyzed from coral core from the Seribu Islands reef complex i.e Jukung Island. SST from ERSST dataset and air temperature measured at Jakarta is used for Sr/Ca calibration. The results show that Jukung Island coral Sr/Ca correlates better with SST than with air temperature. A comparison between the Sr/Ca records with the Nino 3.4 index shows that Jukung coral sites indicate warming sea surface temperatures during the beginning of El Nino events followed by cooling temperatures at the end of El Nino years.
We present a high-resolution study of five geochemical components of a New Caledonia coral core. Minor and trace elements (Sr/Ca, U/Ca, Mg/Ca, Ba/Ca), together with oxygen isotopes (δ18O), were investigated at near-fortnightly resolution. Geochemical measurements were compared to sea surface temperature (SSTTSG) and salinity (SSSTSG) recorded by a thermosalinograph (TSG) located less than 10 m from the coral. Results show that Sr/Ca, Mg/Ca, and δ18O are temperature-dependent (correlation coefficient to local SSTTSG between 0.74 and 0.84). Their robustness as SST tracers is tested against a satellite-based data set for a 4 year validation period. U/Ca has a more complex behavior and appears to be linked to both SSTTSG and SSSTSG, despite relatively small local SSS variations. For the first time this salinity-related imprint is quantified in a U/Ca coralline ratio. In addition to SST and SSS tracers, Ba/Ca measurements provide a possible way to investigate upwelling activity occurrences.
This study provides the first monthly resolved, 41-year record of geochemical variations (delta18O and Sr/Ca) in a fast-growing Diploria strigosa brain coral from Guadeloupe, Caribbean Sea. Linear regression yields a significant correlation of coral Sr/Ca (delta18O) with instrumental sea surface temperature (SST) on both monthly and mean annual scales (e.g., r = -0.59 for correlation between Simple Ocean Data Assimilation (SODA) SST and Sr/Ca, and r = -0.66 for delta18O mean annual scale, p < 0.0001). The generated coral Sr/Ca (delta18O)-SST calibration equations are consistent with each other and with published equations using other coral species from different regions. Moreover, a high correlation of coral Sr/Ca and delta18O with local air temperature on a mean annual scale (r = -0.78 for Sr/Ca; r = -0.73 for delta18O p < 0.0001) demonstrates the applicability of geochemical proxies measured from Diploria strigosa corals as reliable recorders for interannual temperature variability. Both coral proxies are highly correlated with annual and seasonal mean time series of major SST indices in the northern tropical Atlantic (e.g., r = -0.71 for correlation between the index of North Tropical Atlantic SST anomaly and Sr/Ca, and r = -0.70 for delta18O mean annual scale, p < 0.001). Furthermore, the coral proxies capture the impact of the El Niño-Southern Oscillation on the northern tropical Atlantic during boreal spring. Thus fast-growing Diploria strigosa corals are a promising new archive for the Atlantic Ocean.
The oxygen isotopic composition
(δ18Oaragonite) of coral aragonite is
dependent upon two parameters, temperature and water oxygen isotopic
composition. This tracer allows temperature reconstruction in tropical
zones. Different published δ18O:temperature
relationships show a slope derived from the regression
δ18O against T(°C) which varies between -0.16
and -0.23 for Porites genus. This implies greater uncertainty for
paleoclimatic reconstruction. The calibrations were generated
differently. They were obtained from several colonies, collected in
different locations or the formula was derived from the same coral head
following seasonal variations of temperature. The relationships took
into account of δ18OSw fluctuation or
δ18OSw were estimated from salinity or were
not considered. We show by using isotopic data from Weber and Woodhead
(1972) and assessing the δ18OSw value by two
different methods that a thermodynamically significant formula is
generated.
Rainfall from 63 stations across Indonesia is examined for the period 1950-98 to determine the spatial coherence of wet season anomalies. An example of almost unrelated anomalies at two neighboring stations is presented. Principal component analysis is used to quantify the spatial coherence across the entire region. The significant components show high loadings over only a small region, suggesting that rainfall in only this small region varies coherently on an interannual timescale. Correlation with the Southern Oscillation index (SOI) shows that rainfall over only this same region is being largely governed by the El Niño-Southern Oscillation (ENSO) phenomenon. In contrast, a similar analysis for the transition season (Sep-Nov) rainfall shows coherence across almost the entire region and a similarly large area of high correlation with the SOI. Results for all seasons are summarized with the use of an all-Indonesian rainfall index constructed from an averaged percentile ranking of seasonal rainfall from each station across the region. At the times of the year when a large (small) percentage of the variance of rainfall is described by the lowest-order principal components, there is a large (small) correlation between the SOI and the all-Indonesian rainfall index. The implication is that wet season rainfall in Indonesia is inherently unpredictable.
The characteristics of climatic rainfall variability in Indonesia are investigated using a double correlation method. The results are compared with empirical orthogonal function (EOF) and rotated EOF methods. In addition, local and remote responses to sea-surface temperature (SST) are discussed. The results suggest three climatic regions in Indonesia with their distinct characteristics. Region A is located in southern Indonesia from south Sumatera to Timor island, southern Kalimantan, Sulawesi and part of Irian Jaya. Region B is located in northwest Indonesia from northern Sumatra to northwestern Kalimantan. Region C encompasses Maluku and northern Sulawesi. All three regions show both strong annual and, except Region A, semi-annual variability. Region C shows the strongest El Niño-southern oscillation (ENSO) influence, followed by Region A. In Region B, the ENSO-related signal is suppressed. Except for Region B, there are significant correlations between SST and the rainfall variabilities, indicating a strong possibility for seasonal climate predictions. March to May is the most difficult season to predict the rainfall variability. From June to November, there are significant responses of the rainfall pattern to ENSO in Regions A and C. A strong ENSO influence during this normally dry season (June to September) is hazardous in El Niño years, because the negative response means that higher SST in the NIÑO3 of the Pacific region will lower the rainfall amount over the Indonesian region. Analyses of Indonesian rainfall variability reveal some sensitivities to SST variabilities in adjacent parts of the Indian and Pacific Oceans.
The interplay of the El Niño Southern Oscillation, Asian monsoon and Indian Ocean Dipole (IOD)1-3 drives climatic extremes in and around the Indian Ocean. Historical4,5 and proxy6-9 records reveal changes in the behaviour of the El Niño Southern Oscillation and the Asian monsoon over recent decades10-12. However, reliable instrumental records of the IOD cover only the past 50 years1,3, and there is no consensus on long-term variability of the IOD or its possible response to greenhouse gas forcing13. Here we use a suite of coral oxygen-isotope records to reconstruct a basin-wide index of IOD behaviour since AD 1846. Our record reveals an increase in the frequency and strength of IOD events during the twentieth century, which is associated with enhanced seasonal upwelling in the eastern Indian Ocean. Although the El Niño Southern Oscillation has historically influenced the variability of both the IOD and the Asian monsoon3,8,10, we find that the recent intensification of the IOD coincides with the development of direct, positive IOD-monsoon feedbacks. We suggest that projected greenhouse warming may lead to a redistribution of rainfall across the Indian Ocean and a growing interdependence between the IOD and Asian monsoon precipitation variability.
The Ifaty coral record from off SW Madagascar provide a 336-year coral oxygen isotope record that is used to investigate the natural variability of the western Indian Ocean subtropical SST dipole and ENSO. The coral oxygen isotope record primarily reflects past sea-surface temperature (SST) variability on seasonal to multidecadal scales. To validate the SST reconstructions derived from oxygen isotopes, Sr/Ca ratios were obtained for selected time windows (1973-1995, 1863-1910, 1784-1809, 1688-1710). The period 1675-1760 was found to be the coolest period of the entire record with anomalies of 0.3-0.5 °C that includes the Late Maunder Minimum (1675-1710). The warmest periods, as indicated by our data, occur between 1880 and 1900 and the upper part of the Ifaty record (1973-1995).
The stable isotopic composition of scleractinian corals (Porites sp.), two recent and one fossil, from the Egyptian Red Sea coast was studied. The oxygen isotope record proves the assumption that recent sea surface temperatures are comparable to the time of last sea level highstand in Eemian (stage 5e, 125,000 yBP). Deposition of high-density and low-density bands in respect to season shows the same patterns as today with high-density band deposition in winter (low water temperatures) and low-density band deposition in summer (high water temperatures). d18O is negatively correlated with d13C with a shift in phase of 1 to 2 months. Thus a coupling of carbon isotopes to light intensity and oxygen isotopes to water temperature is suggested. To get an overview on seasonal patterns of stable isotope composition a sampling technique with a resolution of four samples per year is of sufficient precision.
The 20th century evolution of basin-wide gradients in surface ocean properties provides one essential test for recent models of the interaction between the Asian monsoon and the tropical ocean, because various feedback mechanisms should result in characteristic regional patterns of variability. Although the instrumental record of climate variability in the tropics is essentially limited to the last few decades, the stable isotopic composition of living corals provides an effective means for extending the instrumental observations. Here we present two coral isotopic records from the Indonesian Maritime Continent, and we use these records with other previously published records to describe: (i) the relationship between western Pacific and central Pacific climate variability over the past century, with special emphasis on the biennial band; and (ii) the strength of the west^east 'Indian Ocean Dipole'. We find that the amplitude of the biennial cycle in the Pacific did not vary inversely with the strength of ENSO (El Nin ‹ o Southern Oscillation), as might be expected from some models of monsoonal feedback on the central Pacific. Instead, the biennial variability was modulated on decadal timescales throughout much of the Pacific. We also show that the zonal oxygen isotopic gradient in the Indian Ocean coral records was significantly correlated with central Pacific sea surface temperature on a variety of timescales. Thus, it is likely that this 'coral dipole' was a product of strong ENSO-like teleconnections over the Indian Ocean, as opposed to being the result of unique Indian Ocean or monsoonal dynamics.
In many regions the strength of El Niño—Southern Os-cillation (ENSO) teleconnections has varied over the last century. It is an active area of research to investigate how such changes can be related to long-term climate variability or climate change. However, fluctuations due to the lim-ited observational record and the low signal/noise ratio also contribute to variations in the apparent strength of the tele-connections. These contributions are considered at 658 pre-cipitation stations around the globe. For each station the probability is estimated that the observed decadal variations in the effect of ENSO on precipitation are due only to sta-tistical fluctuations of a constant teleconnection. There are very few patterns apparent in stations with statistically significant variations. Moreover, the number of these stations is close to the number expected from chance alone. This implies that physical changes in teleconnections are almost everywhere small compared to the statistical fluc-tuations in the observations.
Global analyses of monthly sea surface temperature (SST) anomalies from 1856 to 1991 are produced using three statistically based methods: optimal smoothing (OS), the Kaiman filter (KF) and optimal interpolation (OI). Each of these is accompanied by estimates of the error covariance of the analyzed fields. The spatial covariance function these methods require is estimated from the available data; the timemarching model is a first‐order autoregressive model again estimated from data. The data input for the analyses are monthly anomalies from the United Kingdom Meteorological Office historical sea surface temperature data set (MOHSST5) [ Parker et al. , 1994] of the Global Ocean Surface Temperature Atlas (GOSTA) [ Bottomley et al ., 1990].
These analyses are compared with each other, with GOSTA, and with an analysis generated by projection (P) onto a set of empirical orthogonal functions (as in Smith et al . [1996]). In theory, the quality of the analyses should rank in the order OS, KF, OI, P, and GOSTA. It is found that the first four give comparable results in the data‐rich periods (1951–1991), but at times when data is sparse the first three differ significantly from P and GOSTA. At these times the latter two often have extreme and fluctuating values, prima facie evidence of error. The statistical schemes are also verified against data not used in any of the analyses (proxy records derived from corals and air temperature records from coastal and island stations). We also present evidence that the analysis error estimates are indeed indicative of the quality of the products. At most times the OS and KF products are close to the OI product, but at times of especially poor coverage their use of information from other times is advantageous.
The methods appear to reconstruct the major features of the global SST field from very sparse data. Comparison with other indications of the El Niño‐Southern Oscillation cycle show that the analyses provide usable information on interannual variability as far back as the 1860s.
Spatial and temporal rainfall analysis of the Brantas Catchment Area (DAS Brantas), East Java, from 1955 to 2005 based on 40 rainfall stations with monthly rainfall data derived from daily rainfall data has been performed. To identify the climatic trend and annual changes in the area over the last five decades, we use the empirical orthogonal function (EOF) method based on multivariate statistics, followed by the fast Fourier transform (FFT) method for the power density spectrum analysis, the non-parametric Mann-Kendall trend test and the wavelet transform method. With EOF, we found the monsoonal rainfall pattern as the most dominant in this area, which explains about 72% of all variances. Without the annual signal, the leading EOF shows significant ENSO-modulated inter-annual and seasonal variabilities, especially during the second transitional period. We found a common and significant negative trend of accumulated rainfall and a negative trend of the monsoonal strength and dominance. This finding leads to changes in the annual pattern, which are increase in the ratio of rainfall during the wet season and increase of the dry spell period or the imbalance of the annual pattern. The increased ratio of the rainfall in the wet season has led to an increased threat of drought in the dry season and extreme weather in the wet season in recent decades. The role of the orographic effect had been detected from the decadal pattern, in which the high-altitude areas have greater rainfall amount all year round. From the decadal isohyets in December/January/February (DJF) and June/July/August (JJA), the rainfall amount decreased significantly during the last five decades as shown by a persistent increase of areas with low rainfall amount. By comparing the time series of rainfall data in two locations, the mountain and coastal areas, we discovered that the dry periods have increased, mainly in the low altitude area. Copyright © 2007 Royal Meteorological Society
We reconstruct SST from coral Sr/Ca ratios measured at three coral cores taken from the lagoon of Tahiti (French Polynesia).
Two coral cores were drilled from the same coral colony (one horizontally and one vertically), and a third core was drilled
vertically from another coral growing at a different site. We evaluate several Sr/Ca records as proxies for regional SST variations:
(1) the three single-core records from Tahiti, (2) an average Sr/Ca record computed from the two cores drilled from the same
coral colony, (3) an average Sr/Ca record computed from all three Tahiti cores, and (4) an average Sr/Ca record computed from
the three Tahiti cores and a fourth core taken from a different island (Rarotonga). On a monthly scale, the average Sr/Ca
record including the four coral cores from Tahiti and Rarotonga shows the best correlation with regional SST. The variance
of the SST reconstruction is very realistic and the residual SST is low. This suggests that reconstructing SST from average
proxy records gives a better representation of regional SST variations. Of the three Tahiti cores, the one that was drilled
horizontally shows the best correlation with grid-SST on an annual mean scale. All three Tahiti corals show much larger interannual
SST variations than that indicated by grid-SST.
Very few coral reefs are located close enough to metropolitan cities to study the influence of large urban populations on
reef communities. Here, we compare the impact of a large-scale disturbance gradient with local-scale disturbance on coral
richness, cover, and composition in the Jakarta Bay and Pulau Seribu reef complex off Jakarta, Indonesia. We found no effect
of local land-use type of coral reef islands on richness, composition or cover, nor did taxon richness differ among zones
at the large-scale. There was, however, a pronounced difference in composition and coral cover among zones. Cover was very
low and composition differed markedly in the near-shore zone 1 (Jakarta Bay) where human-induced disturbance is most intense.
Cover was highest in the outlying reefs of zone 3. The highly perturbed zone 1 reefs were, furthermore, distinguished by the
virtual absence of otherwise abundant coral taxa such as Acropora hyacinthus and Porites rus and the prevalence of taxa such as Oulastrea crispata and Favia maxima. Almost 60% of the spatial variation in composition was related to variation in shelf depth and island size. The importance
of shelf depth was related to the prevalence of a strong environmental gradient in reef depth, pollution, and mechanical reef
disturbance and salinity from Jakarta Bay to the outlying reefs. Although there was a significant univariate relationship
between spatial variation in composition and distance, this did not enter into the multivariate model, except when presence–absence
data was used, indicating that environmental processes are the primary structuring forces in determining local coral assemblage
composition across the Pulau Seribu complex.
Recent studies show that SouthEast Indian Ocean (SEIO) SSTs are a highly significant precursor of transitions of the whole
monsoon-El Niño-Southern Oscillation (ENSO) system during recent decades. However, the reasons for this specific interannual
variability have not yet been identified unequivocally from the observations. Among these, the possibility of SEIO SST-driven
variability in the monsoon-ENSO system is investigated here by inserting positive/negative SEIO temperature anomalies in the
February’s restart files of a state-of-the-art coupled General Circulation Model (GCM) for 49years of a control simulation.
For each year of the control simulation, the model was then integrated for a 1-year period in fully coupled mode. These experiments
show that Indian Summer Monsoon (ISM) and tropical Indian Ocean Dipole Mode (IODM) events are significantly influenced by
the SEIO temperature perturbations inserted in the mixed layer of the coupled GCM several months before. A warm SEIO perturbation,
inserted in late boreal winter, slowly propagates northward during the following seasons, implies enhanced ISM rainfall and
finally triggers a negative IODM pattern during boreal fall in agreement with observations. A reversed evolution is simulated
for a cold SEIO perturbation. It is shown that the life cycle of the simulated SEIO signal is driven by the positive wind-evaporation-SST,
coastal upwelling and wind-thermocline-SST feedbacks. Further diagnosis of the sensitivity experiments suggests that stronger
ISM and IODM variabilities are generated by excluding the El Niño years of the control simulation or when the initial background
state in the SEIO is warmer. This finding confirms that IODM events may be triggered by multiple factors, other than ENSO,
including subtropical SEIO SST anomalies. However, the ENSO mode does not react significantly to the SEIO temperature perturbation
in the perturbed runs even though the simulated Pacific pattern agrees with the observations during boreal fall. These discrepancies
with the observations may be linked to model biases in the Pacific and to the too strong ENSO simulated by this coupled GCM.
These modeling evidences confirm that subtropical Indian Ocean SST anomalies generated by Mascarene high pulses during austral
summer are a significant precursor of both ISM and IODM events occuring several months later.
Corals offer a rich archive of past climate variability in tropical ocean regions where instrumental data are limited and where our knowledge of multi-decadal climate sensitivity is incomplete. In the eastern equatorial Pacific, coral isotopic records track variations in ENSO-related changes in sea-surface temperature; further west, corals record variability in sea-surface temperature and rainfall that accompanies zonal displacement of the Indonesian Low during ENSO events. These multi-century records reveal previously unrecognised ENSO variability on time scales of decades to centuries. Outside the ENSO-sensitive equatorial Pacific, long-term trends towards recent warmer/wetter conditions suggest the tropics respond to global forcings. New coral paleothermometers indicate that surface-ocean temperatures in the tropical southwestern Pacific were depressed by 4–6°C during the Younger Dryas climatic event and rose episodically during the next 4000 yr. High temporal-resolution measurements of Sr/Ca and in corals provide information about the surface-ocean hydrologic balance and can resolve the seasonal balance between precipitation and evaporation. Radiocarbon measurements in corals, coupled with ocean circulation models, may be used to reconstruct near-surface ocean circulation, past mixing rates, and the distribution of fossil fuel CO2 in the upper ocean. Most recently, seasonal to interannual variations in the radiocarbon of corals from the equatorial Pacific have been linked to the redistribution of surface waters associated with the ENSO.
Very few coral reefs are located close enough to large cities to study the influence of large urban populations on reef assemblages. An exception is the Thousand Islands reef complex to the north of Jakarta, the capital city of Indonesia, and one of the largest conurbations in the world. Here we present data from a detailed survey where sponge assemblages were assessed at 30 patch reefs associated with islands in three coastal zones along an in-to-offshore gradient. Sponge assemblages are described at three taxonomic levels of detail (species, genus and family level). We recorded a total of 118 sponge species, 64 genera and 36 families, Aaptos suberitoides (Brønsted, 1934), Clathria (Thalysias) reinwardti (Vosmaer, 1880), Petrosia (Petrosia) nigricans (Lindgren, 1897) and Xestospongia testudinaria (Lamarck, 1813) were the most common species overall. There was a pronounced difference in composition among zones with the most distinct difference between the inshore zone and the other two zones. The inshore environment was characterised by very high turbidity and low live coral cover; the dominant substrate consisted of algal turf and sand. Environmental conditions improved and sponge diversity increased further offshore, although most areas appeared to have been affected by some form of disturbance. Ordinations were also largely congruent, at species, generic and family levels of taxonomic resolution. This indicates that variation in composition at higher taxonomic levels is a good indicator of variation at lower taxonomic levels, at least when there is a pronounced environmental gradient.
In order to manage and conserve coral reefs it is essential to understand the factors that structure reef communities. In Indonesia’s Jakarta Bay – Pulau Seribu reef complex, pronounced on-to-offshore variation in a number of variables was observed. Live coral cover, and echinoderm and fish species richness were higher in midshore sites than either in- or offshore sites. Variation in habitat structure, the abiotic environment, distance between sample sites and covariation of these factors separately explained 9.6 to 15.1%of the spatial variation in the composition of corals, echinoderms and fishes. Together, all three components explained > 50%of the variation in composition. This indicates that spatial and environmental factors influence the distribution of species across the study area and have important implications for the large-scale management of this reef ecosystem. Large scale management and protection of these reefs will probably be important because the majority or reefs were in poor to very poor condition as exemplified by low (<25%) coral cover. The coral cover of some inshore reefs was particularly low (< 1%). Inshore coral assemblages tended to be composed of stress-tolerant or specialised pioneers of highly perturbed environments. There were also locally high densities of potentially destructive species such as the sea urchin Diadema setosum. Midshore sites had relatively high coral cover comprising Acropora and Montipora spp. that were rare or absent elsewhere, presumably due to their sensitivity to pollution and mechanical damage. Most of the offshore sites had relatively low live coral cover and were dominated by rapidly growing pioneers or by stress- or –sediment-tolerant species. Spatial variation in the composition of taxa is discussed in the context of past-and-ongoing disturbances, including land-based pollution, coral mining, sedimentation and destructive fishing practices.
We present a 271-year record of Sr/Ca variability in a coral from Rarotonga in the South Pacific gyre. Calibration with monthly sea surface temperature (SST) from satellite and ship measurements made in a grid measuring 1 degrees by 1 degrees over the period from 1981 to 1997 indicates that this Sr/Ca record is an excellent proxy for SST. Comparison with SST from ship measurements made since 1950 in a grid measuring 5 degrees by 5 degrees also shows that the Sr/Ca data accurately record decadal changes in SST. The entire Sr/Ca record back to 1726 shows a distinct pattern of decadal variability, with repeated decadal and interdecadal SST regime shifts greater than 0. 75 degrees C. Comparison with decadal climate variability in the North Pacific, as represented by the Pacific Decadal Oscillation index (1900-1997), indicates that several of the largest decadal-scale SST variations at Rarotonga are coherent with SST regime shifts in the North Pacific. This hemispheric symmetry suggests that tropical forcing may be an important factor in at least some of the decadal variability observed in the Pacific Ocean.
Approximately 10 million m3 x s(-1) of water flow from the Pacific Ocean into the Indian Ocean through the Indonesian seas. Within the Makassar Strait, the primary pathway of the flow, the Indonesian throughflow is far cooler than estimated earlier, as pointed out recently on the basis of ocean current and temperature measurements. Here we analyse ocean current and stratification data along with satellite-derived wind measurements, and find that during the boreal winter monsoon, the wind drives buoyant, low-salinity Java Sea surface water into the southern Makassar Strait, creating a northward pressure gradient in the surface layer of the strait. This surface layer 'freshwater plug' inhibits the warm surface water from the Pacific Ocean from flowing southward into the Indian Ocean, leading to a cooler Indian Ocean sea surface, which in turn may weaken the Asian monsoon. The summer wind reversal eliminates the obstructing pressure gradient, by transferring more-saline Banda Sea surface water into the southern Makassar Strait. The coupling of the southeast Asian freshwater budget to the Pacific and Indian Ocean surface temperatures by the proposed mechanism may represent an important negative feedback within the climate system.
We determined Pb contents together with Pb isotopic compositions in coral skeletons (Porites spp.) collected from the western Pacific and adjacent seas to examine distribution of Pb in sea surfaces. Temporal records of Pb were also investigated using coral skeletons from Hainan and Ogasawara Island, located in China and Japan, respectively. The spatial distribution of Pb showed a clear dilution pattern of Pb from Asian continent to the open ocean. Also the similar trend was found in the Java Sea from Jakarta to the offshore. In addition to the spatial distribution, Pb contents in Ogasawara coral have gradually increased during last 108 years. It may be attributed to Pb emission mainly from industrial activities in Asian countries. Hainan coral, which provided 10 years record of Pb, showed a remarkable decline around 1997 probably due to the partial introduction of unleaded gasoline in China.
The Indian Ocean Dipole (IOD)--an oscillatory mode of coupled ocean-atmosphere variability--causes climatic extremes and socio-economic hardship throughout the tropical Indian Ocean region. There is much debate about how the IOD interacts with the El Niño/Southern Oscillation (ENSO) and the Asian monsoon, and recent changes in the historic ENSO-monsoon relationship raise the possibility that the properties of the IOD may also be evolving. Improving our understanding of IOD events and their climatic impacts thus requires the development of records defining IOD activity in different climatic settings, including prehistoric times when ENSO and the Asian monsoon behaved differently from the present day. Here we use coral geochemical records from the equatorial eastern Indian Ocean to reconstruct surface-ocean cooling and drought during individual IOD events over the past approximately 6,500 years. We find that IOD events during the middle Holocene were characterized by a longer duration of strong surface ocean cooling, together with droughts that peaked later than those expected by El Niño forcing alone. Climate model simulations suggest that this enhanced cooling and drying was the result of strong cross-equatorial winds driven by the strengthened Asian monsoon of the middle Holocene. These IOD-monsoon connections imply that the socioeconomic impacts of projected future changes in Asian monsoon strength may extend throughout Australasia.
Describes the biota, natural values and the threats to the proposed park based on the Thousand Islands off Jakarta. This will be the first wholly marine national park to be designated in Indonesia. Information is summarized for all zones of the park giving details of compatible uses, restrictions, and wildlife values to be protected.-R.Land
The Indonesian Throughflow (ITF), which represents the global ocean circulation connecting the Pacific Warm Pool to the Indian Ocean, strongly influences the Indo-Pacific climate. ITF monitoring since the late 1990s using mooring buoys have provided insights on seasonal and interannual timescales. However, the absence of longer records limits our perspective on its evolution over the past century. Here, we present sea-surface temperature (SST) and salinity (SSS) proxy records from Timor Island located at the ITF exit passage via paired coral δ18O and Sr/Ca measurements spanning the period 1914-2004. These high-resolution proxy based climate data of the last century highlights improvements and cautions when interpreting paleoclimate records of the Indonesian region. If the seasonality of SST and SSS is not perfectly in phase, the application of coral Sr/Ca thermometry improves SST reconstructions compared to estimates based on coral δ18O only. Our records also underline the importance of ocean advection besides rainfall on local SSS in the region. Although the El Niño/Southern Oscillation (ENSO) causes larger anomalies relative to the Indian Ocean Dipole (IOD), Timor coral-based SST and SSS records robustly correlate with IOD on interannual timescales, whereas ENSO only modifies Timor SST. Similarly, Timor SST and SSS are strongly linked to Indian Ocean decadal-scale variations that appear to lead Timor oceanographic conditions by about 1.6-2 years. Our study sheds new light on the complex signatures of Indo-Pacific climate modes on SST and SSS dynamics of the ITF.
Characteristics of sea-breeze circulation over the tropical site of Jakarta. Indonesia, have been documented based on analyses of satellite images and data from long-term L-band boundary layer radar measurements carried out at Serpong (6.4°S, 106.7°E). Inspection of satellite imagery reveals that a sea-breeze front develops well along the northern coastal plain of West Java and propagates inland until its structure is deformed over complex topography. It is found that the sea-breeze signal detected by the boundary layer radar is most well defined during the dry season months of July-October. In all of these months, radar observations indicate a late afternoon intensification of sea-breeze flow in the 0.5-0.8-km height range between 1700 and 1800 LT, which is not elucidated upon by surface measurements. The effect of weather conditions on the sea-breeze pattern is investigated by using a cloudiness index derived from data of incoming solar radiation. The results show that sea-breeze intrusion over the radar site occurs earlier during more cloudy days, whereas the intensity of sea-breeze circulation weakens accordingly. In the rainy season months of January and February, diurnal wind variation is characterized by daytime onshore flow enhancement, which is not likely attributed to sea-breeze circulation.
Observations of sea surface and land-near-surface merged temperature anomalies are used to monitor climate variations and to evaluate climate simulations; therefore, it is important to make analyses of these data as accurate as possible. Analysis uncertainty occurs because of data errors and incomplete sampling over the historical period. This manuscript documents recent improvements in NOAA's merged global surface temperature anomaly analysis, monthly, in spatial 5° grid boxes. These improvements allow better analysis of temperatures throughout the record, with the greatest improvements in the late nineteenth century and since 1985. Improvements in the late nineteenth century are due to improved tuning of the analysis methods. Beginning in 1985, improvements are due to the inclusion of bias-adjusted satellite data. The old analysis (version 2) was documented in 2005, and this improved analysis is called version 3.
In the Pacific Ocean, the coherent pattern of interdecadal variations in sea surface temperature (SST) over the last 3100 years has been termed the Inter-decadal Pacific Oscillation (IPO). To examine past variations in the IPO we have generated time series of Sr/Ca and oxygen isotopes (d 18 O) from South Pacific Porites coral colonies growing at Rarotonga (1997 to 1726) and Fiji (1997 to 1780). At both sites skeletal Sr/Ca is highly correlated with instrumental SST at least back to 31970 and d 18 O appears to reflect both SST and South Pacific Convergence Zone (SPCZ) effects on seawater d 18 O. Comparison of our results to a New Caledonia coral d 18 O record and to indices of inter-decadal Pacific climate variability demonstrates that these South Pacific corals have accurately recorded twentieth century variations in the IPO and SPCZ. The coral records also indicate that higher amplitude and more spatially coherent IPO-related variability existed from 1880 to 1950 with notably poor between-site cor-relations in the mid-1800s. These observations suggest that the spatial IPO pattern in South Pacific SST was significantly more complex and/or poorly defined in the mid-1800s compared to that observed in the twentieth century. Comparison with North Pacific IPO indices also indicates that the degree of cross-hemispheric symmetry of interdecadal oceanographic variability has changed over time with a lower correlation between the North and South Pacific in the mid-1800s. This evidence suggests that the spatial pattern of the IPO at least in the South Pacific has varied over the last 300 years, with a major reorganization occurring after 31880 A.D.
Extensive coral bleaching occurred during sea-water warming (as a result of the 1982/3 El Nio Southern Oscillation event) in 1983 on the shallow reefs in the Java Sea. Mean seawater temperatures rose by 2–3 C over a six month period with values greater than 33 C being recorded between 1200–1500 h. As many as 80–90% of corals died on the reef flats at the study sites, with the major casualties being branching species in the genera Acropora and Pocillopora. Five years after the event the community structure of the study sites has recovered significantly, though coral cover is still 50% of its former level. Contrasting patterns of recovery at two selected sites, in close proximity to each other, are discussed.
Shallow water Porites lutea corals were collected along two transects normal to mainland shorelines, parallel to gradients in water quality: one, 7 km long, near Motupore Island in South Papua New Guinea, the other, 70 km long, from Jakarta Bay along the Pulau Seribu chain in the Java Sea. The corals were slabbed and studies were made of skeletal density bands as revealed by X-ray photography and fluorescent bands as revealed by ultraviolet light. Water quality measurements and rain-fall data were assembled for the two areas and related to skeletal banding patterns. For both areas, with increasing distance form mainland there is a decrease in overall brightness of fluorescence in corals and an increase in the contrast between bright and dull fluorescent bands. Fluorescence is bright, but seasonal banding is obscure in corals within about 2 km of stream mouths at Motopure and about 5 km of the coast in Jakarta Bay; this suggests that, despite low freshwater run-off during dry seasons, there are sufficient organic compounds which cause fluorescence in coral skeletons, to swamp seasonal effects. During the wet seasons, deluges of freshwater consequent on mainland rainfall of greater than about 150 mm/ month extend at least 7 km offshore in the Motupore area and perhaps tens of kilometres into Java Sea, giving distinctive bright and dull fluorescent banding in off-shore corals. The fluorescent banding pattern within corals on the Motupore reefs is similar in most corals along the transect and it correlates well with the Port Moresby monthly rainfall data. This relationship suggests that the same body (or bodies) of freshwater affect all reefs of the area during the wet season. The fluorescent banding in Java Sea corals does not show a precise correlation with either mainland or island monthly rainfall data; indeed the pattern of fluorescent banding on Pulau Seribu can only be matched in corals from reefs less than about 25 km apart. This suggests that in this area discrete water bodies carrying the relevant organic acids for coral fluorescence affect the fringing reefs on the chain of islands. Comparisons of fluorescent and density banding have revealed that for these areas, in general, periods of high freshwater run-off are times of deposition of less dense skeleton in Porites lutea corals.
Massive scleractinian corals secrete an aragonitic skeleton which incorporates a large array of chemical tracers. Corals present several advantages for palaeoclimate research: they grow continuously, and can live up to 1000 years; they are easy to date; and they can be sampled at high resolution (weekly to monthly resolution). Both live and fossil corals can be collected in the field. In the past two decades, significant efforts have been made to identify robust tracers of sea surface temperature (SST) and salinity (SSS) in corals. To date, Sr/Ca and δ18O are considered to be the most reliable SST tracers, although changes in seawater δ18O can significantly alter SST reconstructed from coralline δ18O. Because these variations in seawater δ18O can be linked to SSS changes, this initial problem can in fact be turned into an advantage and provide us with an SSS tracer. The SST component in the coral δ18O signal can either be evaluated through Sr/Ca measurements, or in some case simply filtered out. However, there is still much uncertainty concerning the exact mode of incorporation of trace elements and stable isotopes into the coral skeleton. The effects of growth rate, light intensity, feeding habits, pH and water chemistry are still poorly documented. A review of the strength and weaknesses of Sr/Ca and δ18O is presented, together with some examples of SST and SSS reconstructions. Other potential SST tracers are also reviewed. It is expected that the ability to grow corals in aquarium under controlled conditions, and that the development of sophisticated analytical techniques at the micrometric level should help us understand better the robustness of each tracers and the factors controlling their incorporation in coral aragonite.
A key question in ecology is how biological traits of species determine their locations within an ecosystem. Identifying associations between species traits and environmental variables can help us to understand the causes of disturbance and predict whether species with given traits will persist under changing environmental conditions. To this end corals and environmental variables were sampled in 20 patch reefs of Pulau Seribu, located to the northwest of Jakarta, Indonesia. RLQ analysis, a multivariate ordination approach was subsequently used to relate species traits (colony shape, colony form, corallite size, reproductive mode and adaptive strategy) to environmental variables (e.g., heavy metal concentration in seawater and sediment, salinity, dissolved oxygen, and the cover of sand, dead coral, algae, sponges and soft corals). Using RLQ analysis, we identified environmental gradients associated with significant variation in species traits. Stress tolerant species with a massive morphology, meandroid shape and large corallites were associated with sites with a high abundance of algae and a relatively high concentration of potentially toxic heavy metals in seawater including Cu and Cd, whereas ruderal species and species with a branching morphology and very small corallites were linked to midshore sites. Competitively dominant species with a laminar or free-living morphology, phaceloid shape, very large corallites and brooding reproductive mode were linked to offshore sites with abundant Ca and Sr in the sediment and a high cover of Halimeda algae and sponges. Results of this study indicate that disturbance has differentially affected the marine environment of the Pulau Seribu system, which in turn interacts with coral species traits to determine local species composition.
In 1937/38 representative mollusc collections were made in Jakarta Bay (West Java, Indonesia). New data from here and the adjacent offshore Thousand Islands archipelago (Kepulauan Seribu) became available in 2005. Although collecting efforts and sampling methods differed, a comparison of the molluscan fauna of Jakarta Bay between 1937/38 and 2005 reveals a distinct deterioration. From 1937 to 2005, Jakarta Bay received increasing amounts of sewage from the greater Jakarta area, as well as increased sediment input from the deforested West Java hinterland. Predatory gastropods and numerous mollusc species associated with carbonate (reef) substrate have vanished from Jakarta Bay, among which many edible species.
Calibration of the multicores Sr/Ca records-sea surface temperature: records from Tahiti corals (French Polynesia)
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Coastal city air temperature variation derived from coral Sr/Ca ratios: case study Jakarta, Indonesia
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Cahyarini S.Y., and J. Zinke (2009). Coastal city air temperature variation derived from
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on Integrated Coastal Zone Management, Izmir-Turkey 20-22 October 2009, ISBN
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The coral reefs in the Bay of Batavia
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Coral diversity across a disturbance gradient in the
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