Dear Du,

this is not easy to answer in one go. As usual, it depends....

Porites is a slow growing coral and very high sedimentation rates, particularly in estuary areas, will simply cover and kill the coral. There are other coral species, who can actually "stick their polpys" through the mud - I have seen this e.g. in front of Padang, Indonesia with Goniopora and other species.

on the other hand, Porites corals are sometimes growing very big and high, and when conditions change and sedimentation rates increase, it can take many years until a Porites is really outcompeted.

So you would have to specifiy - is "your" sedimentation continous throughout the year, or a seasonal event ? What rates are you talking about ?

Do you have large Porites in front of river mouths ?

Regards

Andreas

Dear Hoang

Rogers (1990) studied sedimentation effect on coral reef development. Based on the study particle of sediment reduces the light penetration for photosynthesis and change in ecosystem of coral reef. Actually sedimentation is a stress in coral ecosystems. Therefore in this zone fewer coral taxa are detected. Heavy sedimentation changes morphological feature, orientation, growth habit of corals. You can find the mentioned workin link below:

link: http://www.int-res.com/articles/meps/62/m062p185.pdf

The previous studies had been confirmed similar result such as: Iledgpeth et al. (1957) which clearly recoreded obvious change in coral ecosystem by heavy sedimentation. Decreasing in rate of corals where heavy sedimentation take place (see link below).

link: https://books.google.com/books?id=_hTYaxUiRVcC&pg=PA1088&lpg=PA1088&dq=heavy+sedimentation+and+paleoecology+of+tropical+corals&source=bl&ots=XaFRxpHpN4&sig=IpX9kJEKIiYuQxKZMcFAYV60fcc&hl=en&sa=X&ved=0CCsQ6AEwAWoVChMI8ZCP1JWbyAIVTOwUCh1dTQJU#v=onepage&q=heavy%20sedimentation%20and%20paleoecology%20of%20tropical%20corals&f=false

Turbidity of ecosystem is examined by Erftemeijer et al. (2012) which allowed the corals in turbidity position survive duration. As you know that both sedimentation and turbidity affected on coral survive.

link:http://www.sciencedirect.com/science/article/pii/S0025326X12001981

Regards

Massih 

Thanks for your answers. In my question, its was very specific for hard coral like as Porites spp, and the sedimentation rates are strongly varied with seasonal changes. For other hard coral species, I known that many references are published.

Ok, this means that corals have the opportunity to recover from stress. Can you give details about when, and for how long, you will have an increased particle load with increased turbidity etc. ?

And do you know about the turbidity values in the rest of the year ? Is sediment resuspended, and not permanently deposited "on top" of the Porites ?

The USGS has done studies in HI that may help you address this question - I suggest that you review the publications at http://coralreefs.wr.usgs.gov/pubs.html.

Thanks for all suggestion.