OBJECTIVE OF THE STUDY

  • 1. Calculate the rate of sedimentation by using in-situ erected sediment trap.
  • 2. Calculate the rate of sediment transport by using physical parameters such as tide and current pattern.
  • 3. To study the relationships between sedimentation rate and health of the coral reef ecosystem.

STUDY AREA


METHODOLOGY


SEDIMENT TRAPS

Erected sediment trap in the coral reef ecosystem

Sediment deposition rate of Palk Bay and Gulf of Mannar

Benthic biological status of the reef ecosystem

CORAL REEF COVER WITH SEDIMENTATION RATE

Site Live Coral cover*(%) Sedimentation Rate(mg.cm-2.d-1.)
Olaikudah 39.75 28.99
Villunditheertham 11.40 22.27
Munaikaud 12.55 38.54
Kurusadai 39.67 24.79

Relationship between mean live coral cover (%) and Sedimentation rate (mg.cm-2.d-1.)


Relation between Sedimentation rate and the Live Coral cover

Total Suspended Sediment Concentration in the Gulf of Manner and the Palk Bay region of southern Tamil Nadu region

CONCLUSIONS

Coral reefs act as natural barriers and protect the shorelines of islands and land masses against natural calamities. The natural parameters such as light, temperature, salinity and settlement of silt influence the growth of corals. Siltation is one of the major factors influencing the growth and survival of corals. South east coast of India consist of rich diversity of coral reefs are influenced by both southwest and northeast monsoons. Sedimentation rate is calculated from the selected study sites of Palk Bay and Gulf of Mannar reef ecosystem is between the 14.6 and 38.54 mg.cm-2d-1. And the sedimentation rate of Palk bay and Gulf of Mannar is compared and found that, the sedimentation rate of the Palk Bay is ~2 times higher than that of Gulf of Mannar. The model predictions also clearly indicating that the suspended sediments due to high magnitude of coastal currents will allow the deposition of suspended mud on the coral environment. Significant Positive correlation of the model predicted sedimentation value with the collected value is observed from regression equation. Biophysical status of corals and its associated life-form communities (mean cover %) of the corresponding study sites are assessed. Due to high sedimentation rate, the corals presented in Gulf of Mannar and Palk Bay are negatively impacted in the present study (r = -0.47), which requires continuous monitoring in both physical (Sedimentation rate) as well as biological status (Ground truthing on coral reef cover) of the coral reef.


In the present study, the sedimentation rate observed in the field is between 14.6 and 38.54 mg.cm-2.d-1 in the Palk Bay and the Gulf of Mannar which affecting the health of corals. It is also observed that the sedimentation rate of the Palk Bay (29.94 mg.cm-2.d-1) is higher than that of Gulf of Mannar (24.79 mg.cm-2.d-1) due to the circulation pattern.


In modelling, it shows that the bed stress predicted to vary from 0.05 m to 0.75 Nm2 and it is more in the Palk Strait as compared to the Rameshwaram Island. Because it is directly connected to the flow conditions so it affected the tides to form the sediment in the channel. The magnitude of the suspended sediment has varied in the range of 0.04 – 0.56 kg/m3 and is high in the Palk Strait and west side of the Kurusadai Island as compared to the offshore regions.