1. MASS MORTALITY AND RECRUITMENT OF INTERTIDAL MARINE INVERTEBRATES IN CHEK JAWA, SINGAPORE

2. Chek Jawa

3. Chek Jawa is lauded for its high biodiversity with six distinct ecosystems

4. Mass mortality occurred on January 2007

5. Dying Carpet Anemones, Sponges, echinoderms

6. Soft bodied invertebrates affected

8. Results and Discussion

9. Figure: Aerial photograph of Chek Jawa (squared in white) and its surrounding. Photo by Google Earth. Kuala Johore Salinity decreases

12. Incidence of low tide: 11-14 January 2007 1.5 1.6 16:00 1.3 4.4 15:00 1.1 2.3 14:00 1.1 2.3 13:00 1.2 2.4 12:00 14th 1.3 1.1 13:00 1.3 4.6 12:00 13th 1.5 4.7 22:00 1.6 1.9 21:00 1.8 13 14:00 1.6 24.1 13:00 1.4 10.7 12:00 1.3 7.4 11:00 12th 1.6 1.4 0:00 1.4 10.9 23:00 1.3 3.3 22:00 1.3 2.1 21:00 1.4 14.1 11:00 1.3 7.8 10:00 11th Tide level (m) Hourly Rainfall (mm) Hour Jan-07

13. Cumulative rainfall data for January 2007 taken from Changi Meteorological Station Prolonged Prolonged direct rainfall for about three days Mass death first sighted

14. River water-level data taken from Johor River, Kota Tinggi.

15. Six transect lines T1 T2 T3 T4 T5 T6

16. Number of tube worms ( Chaetopterus sp.) between four periods suggests recovery

18. Monitoring Mussel Beds

19. A closer look reaching densities of up to 26,000 + 2738.6 per m 2

20. Musculista senhousia An invasive species

21. A friend or a foe? can dominate and exclude native species by settling in aggregations to reach high densities may restrict growth of some seagrass species provide additional habitat

22. Comparing December 2007 and January 2008 suggests a possibility of mussel beds slowly being replaced away as recovery progresses DEC 2007 JAN 2008

23. August 2008?

24. May 2007 August 2007 October 2007 December 2007 January 2008 August 2008 * * Only mud mounds remain A F B E D C

25. October 2008?

28. Data of other fauna surveyed Establish baseline Nil Nil Nil 16.14 Common sea star ( Archaster typicus ) 12622 + 1921 (15×15)cm 2 284 + 43.2 Nil Button shell ( Umbonium vestiarum ) 15 + 5 (5×5)m 2 15 + 5 5.5 + 0.1 Sand star ( Astropecten sp.) 36 + 12 (1×1)m 2 36 + 12 5.8 + 0.1 Sand dollar ( Arachnoides placenta ) Density (per metre square) Size of quadrat Average count in one quadrat (corrected to whole number) Average diameter (cm) Species

30. Thank you