Shell of Winged Argonaut with aperture facing upwards. Photograph by Letchumi d/o Mani
Winged Argonaut (Argonauta hians shell at Semakau Landfill
Location, date and time: Singapore Strait, Semakau Landfill, western part; 12 November 2015; 1600 hrs.
Observation: As shown in the attached picture, a shell of a female argonaut was found stranded and half-submerged among the roots of a bakau tree (Rhizophora sp.). A hole was observed on the lateral side of the thin, boxy shell of about 8 cm.
Remarks: This appears to be the second record of a Winged Argonaut shell found in Singapore. The first record for the country was also at Semakau Landfill (Lee et al., 2015).
Lee B. Y, S. K. Tan & M. E. Y. Low, 2015. Singapore Mollusca: 9. The family Argonautidae, with a new record of Argonauta hians (Cephalopoda: Octopoda: Argonautoidea). Nature in Singapore. 8: 15-24.
Fig. 1. Aggregation of dead Fluted Giant Clam shells (foreground).
Fig. 2. Close-up view of the Fluted Giant Clam shells in the pile. (Photos by Loh Kok Sheng)
Fluted Giant Clam (Tridacna squamosa) shells ‘graveyard’ at Semakau Landfill
Location, date and time: Singapore Straits, northern part of Semakau Landfill; 1 February 2014; 1800–2000 hrs.
Observation: Giant clams have been an important coastal resource to man as food and for materials across the Indo-West Pacific region (Mingoa-Licuanan & Gomez, 2002). In Singapore, exploitation of giant clams was evident based on early accounts from European travellers (Traill, 1847) and of local fishing practices (Chuang, 1961; Purchon & Purchon, 1981). Physical evidence of exploitation was also discovered during archaeological excavations, where aggregations of tridacnine shells were found at sites previously located along the old coastline of mainland Singapore (Neo & Todd, 2012).
This record adds to the exploitation history of giant clams in Singapore (Neo & Todd, 2012), and represents the largest assemblage of mature shells found so far. The species of interest, Tridacna squamosa, is one of the five species that can still be found in Singapore, but is locally critically endangered (Neo & Todd, 2013). This intensity of exploitation is unsurprising as there have been early accounts of larger clams being preferentially harvested (Harrison & Tham, 1973; Chou, 1984). Such exploitation could explain the current population status — sparsely distributed with few mature individuals, coupled with poor recruitment rates (Neo et al., 2013).
Chou L. M., 1984. The coral reef of Pulau Salu. Singapore Scientist. 10 (2): 60–64.
Chuang S. H., 1961. On Malayan Shores. Muwa Shosa, Singapore. xvi + 225 pp., 112 pl.
Harrison, J. L. & A. K. Tham, 1973. The exploitation of Animals. In: Chuang S. H. (ed.). Animal Life and Nature in Singapore. Singapore University Press. Pp. 251–259.
Mingoa-Licuanan, S. S. & E. D. Gomez, 2002. Giant clam conservation in Southeast Asia. Tropical Coasts. 3: 24–56.
Neo M. L. & P. A. Todd, 2012. Giant clams (Mollusca: Bivalvia: Tridacninae) in Singapore: history, research and conservation. Raffles Bulletin of Zoology. 25: 67–78.
Neo M. L. & P. A. Todd, 2013. Conservation status reassessment of giant clams (Mollusca: Bivalvia: Tridacninae) in Singapore. Nature in Singapore. 6: 125–133.
Neo M. L., P. L. A. Erftemeijer, J. K. L. van Beek, D. S. van Maren, S. L.-M. Teo & P. A. Todd, 2013. Recruitment constraints in Singapore’s Fluted Giant Clam (Tridacna squamosa) population – A dispersal model approach. PLoS ONE. 8 (3): e58819. doi:10.1371/journal.pone.0058819
Purchon, R. D. & D. E. A. Purchon, 1981. The marine shelled mollusca of West Malaysia and Singapore: Part 1. General introduction and an account of the collecting stations. Journal of Molluscan Studies. 47: 290–312.
Traill, W., 1847. A few remarks on conchology and malachology, comprising brief notices of some of the more remarkable “Testacea” in Singapore and its neighbourhood; with an appended catalogue of Singapore shells arranged in conformity with Lammarck’s System. The Journal of the Indian Archipelago and Eastern Sea. 1 (5): 225–241.
Fig. 1. Shark number 1.
Fig. 2. Shark number 2.
Fig. 3. Shark number 3, removed from net.
Photographs by Ron K. H. Yeo
Blacktip Reef Sharks (Carcharhinus melanopterus) at Semakau Landfill
Location, date and time: Singapore Straits, reef flat around Semakau Landfill; 29 May 2010; between 0520 and 0550 hrs.
Observation: Three freshly dead examples of around 1 metre total length were found during early morning low tide, tangled in gill nets set over a reef flat (Fig. 1-3).
Remarks: In Singapore, the Blacktip Reef Shark has been recorded around Semakau Landfill (Ng, 2012: 29, 146). This species does not exceed 2 metres in total length, and is distributed in shallow waters on and around coral reefs throughout the tropical Indian Ocean and western Pacific. It has even invaded the eastern Mediterranean Sea via the Suez Canal (Compagno et al., 2005: 302).
Compagno, L., M. Dando & S. Fowler, 2005. A Field Guide to the Sharks of the World. Harper Collins Publishers Ltd., London. 368 pp.
Ng, M. F. C., 2012. Habitats in Harmony: The Story of Semakau Landfill. Second edition. National Environment Agency, Singapore. 157 pp.