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Title: Vertical zonation and heat tolerance of three littorinid gastropods on a rocky shore at Tanjung Chek Jawa, Singapore
Authors: Lee, Su Li
Lim, Shirley S. L.
Keywords: Zonation
Heat tolerance
Enzyme stability
Littoraria sp.
Echinolittorina malaccana
Echinolittorina vidua
Issue Date: 2009
Citation: Lee, S. L., & Lim, S. S. L. (2009). Vertical zonation and heat tolerance of three littorinid gastropods on a rocky shore at Tanjung Chek Jawa, Singapore. The Raffles Bulletin Of Zoology, 57(2), 551-560.
Abstract: Three common rocky shore littorinid taxa, i.e. Littoraria spp. (a collective term for L. strigata and L. articulate), Echinolittorina malaccana and E. vidua occupied different tidal heights based on field observations carried out at Tanjung [=Cape] Chek Jawa, Pulau [=Island] Ubin, Singapore in 2002. Littoraria spp. were consistently observed at a lower level on the shore than E. malaccana and E. vidua. Manually translated littorinids returned to their preferred zones in the field, i.e., E. malaccana returned to the region above the MHWS level of 2.7 m while Littoraria spp. remained below the region occupied by E. malaccana. Further, E. malaccana individuals with their shell nodules removed by filing did not occupy a lower zone than intact conspecifies in the field. Although significant temperature differences (TD) were observed between rock and surfaces in the laboratory (TD Littoraria = TD filed E. malaccana <TD E. malaccana), preference for a particular height on the shore is probably governed more by physiological factors (e.g. heat tolerance) than by morphological adaptation (e.g., shell morphology). As the upper shore is exposed to the sun for longer periods of time, it is expected that the heat tolerance of inhabitants of the higher shore would be greater than those occupying the lower regions. Results of a 1-hour lethal temperature experiment support this hypothesis: the temperature at which 50% mortality (1h LT50) was observed was highest for E. malaccana (50.4 degree Celsius) compared to E. vidua, (48.1 degree Celsius) compared to E. vidua, (48.1 degree Celsius) and Littoraria spp. (47.5 degree Celsius), possibly reflecting their relative tidal positions on the shore. Enzyme stability may also account for high heat tolerance of E. malaccana . Incubation of the enzyme, glutamate oxaloacetate transaminase (GOT) at 55 degree Celsius showed that E. malaccana sustained high GOT activity compared to those of Littoraria spp. and E. vidua which decreased sharply at the same temperature, again suggesting inherent physiological adaptation in E. malaccana.
ISSN: 0217-2445 (print)
2345-7600 (online)
Appears in Collections:Journal Articles

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