The coral compromises health has contributed to the declining coral cover through coral disease. Compromised health associated with water quality, such as increasing sea surface temperature, a load of nutrients and sedimentation (Nugues & Roberts,2003). Coral compromised health is an unhealthy condition of coral that was not infectious but will leave a wound on coral that potentially damage the host. (Beeden et al., 2008a) gave five categories of coral health compromise they were: pigmentation response, unusual bleaching patterns, competition and aggressive overgrowth by other benthic organisms, sediment damage and flat infestation (Beeden et al., 2008a; Raymundo et al., 2008).
Terrestrial sediments that can carry bacteria have been identified as causing necrosis in coral tissue (Nugues and Robert, 2003). Other biotic and abiotic factors such as chemicals, nutrient imbalances, UV radiation, predation, overgrowth, and infectious diseases are becoming the coral compromised health (Harvell et al., 2007), and these factors can synergize in a reduction of coral cover (Hughes et al., 2003).
The number of nutrients in the sea waters are also an indicator of environmental health. Nutrients are needed for primary productivity in the sea waters but high nutrients in sea waters such as nitrates can lead to increased algal growth (Bricker et al.,2008). Nutrients also have a direct influence on corals. The higher nutrients will increase the growth of algae that can disrupt coral recruitment to cause habitat degradation (Box and Mumby, 2007).
High phosphate in sea waters can affect the success rate of coral fertilization (Harrison and Ward, 2001). Nitrate is also known to affect corals by reducing the calcification rate of a coral skeleton (Marubini and Davies, 1996).
The presence of sediments on surface coral colony will interfere with the coral metabolism due to coral polyps covered by sediment. The sediment damage caused by high sedimentation rates can also interfere with coral reproduction (Beeden et al.,2008a). One research on Acropora digitifera showed that high sedimentation on corals affects the success of coral fertilization and disrupts coral larvae attachment to the substrate (Gilmour, 1999).
The process of fertilization of Acropora milepora was also influenced by sediment (Humphrey et al., 2008). Turbid sea water that contained high sediment in the water column also affects the growth rate of Porites and Acropora corals (Crabbe and Smith, 2005). Competition among benthic species also became the coral compromised health and can affect coral colony death. The benthic competitor and became a threat of coral were sponge, flatworm, cyanobacteria and red filamentous algae (Beeden et al., 2008a).
The coral colonies that overgrow with algae and sponges will suffer bleaching and impact on coral mortality, while flatworms can cause loss of living tissue on corals (Beeden et al., 2008aCoral disease prevalence indicates the number of diseased coral colonies by a number of all coral colonies in a certain area. High prevalence means high pathogen-host, changing environmental from normal condition and stress of coral by increased a surface mucopolysaccharide layer.
The coral disease prevalence in the world is different but the Caribbean’ s sea still become a hot spot area with the prevalence was more 20%, in Australia, Palau and East Africa less for 5% while in Philippine was 8% (Harvell et al., 2007). The prevalence in Indonesia described in Lembata, West Nusa Tenggara was 40%, with the type of coral compromised health was sediment damage and competition-overgrowth (Nugues and Roberts, 2003).
In East Java coral compromised health reported from nature reserve Pulau Sempu about 15%, with types of compromised health was competition and flatworm infestation (Luthfi et al., 2014). North part of Indonesia, Pulau Barrang Lompo, south of Sulawesi the prevalence was lesser from another area about 6,09%. Pigmentation response was a common type of coral compromised health (Massinai et al., 2012).
The Prigi Bay administratively was in Trenggalek, East Java. The coral reef was adhering in reef edge that surrounds this location such as Pulau Rembang, Pasir Putih, Pantai Damas, Umbokarno and Karang Malang (Wibowo and Adrim, 2014). Coral in Prigi Bay may under the treat due to high tourism activity, fish harbor activities and sedimentation came from the river that outfall in Prigi Bay. During preliminary research, a lot of coral rubble and high seawater turbidity be found in all stations. The purpose of this study was to determine the prevalence value of coral health disruption and the effect of environmental parameters on the prevalence of coral health problems in Prigi Bay.
Coral compromised health survey was conducted at 3 stations on Prigi Bay and the data were collected by using a belt transect 1 x 100 m was laid in 7m. The collected data were obtained by underwater photography. The result shows the percentage of coral cover found at station 2 (48.16%), the highest relevance of coral reef health was 75.69% at the station 3 caused by sediment damage. Pearson Correlation Value for NO3 is 0.520, NO2 is 0.630 and sedimentation is 0.343. These environmental factors have strong factors with health prevalence which is compromised.
Further detail about Water quality impact to coral compromised health prevalence of Prigi Bay, East Java, Indonesia can be accessed on the link above.
Title: Water quality impact to coral compromised health prevalence of Prigi Bay, East Java, Indonesia
Writer: Oktiyas Muzaky Luthfi, Abdur Rosyid, Andik Isdianto, Alfan Jauhari, Daduk Setyohadi, Rosdianto and Agoes Soegianto*
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