Lim, Shirley S. L.

In this paper, we discuss our efforts in curriculum development of an environmental science module that will be conducted in a networked teaching and learning environment, complemented by laboratory sessions and field work. The aim of the curriculum is to promote collaborative and distributed learning of environmental science that emphasizes the acquisition of higher order thinking skills. Some aspects of the curriculum that will be highlighted include the contents of an interactive multimedia teaching system for self-paced learning, and scenario generators that allow the participants to experiment with hypothetical environmental situations.

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

Larder hoarding behavior in central place foragers has been widely studied in vertebrates, albeit, not as extensively as scatter hoarding. However, scant information is available for the invertebrate taxa, especially aquatic species. We investigated this phenomenon via an in situ food supplementation experiment in a community of two sympatric fiddler crabs, Austruca annulipes (n = 80; 40 males and 40 females) and Gelasimus vocans (n = 60; 30 males and 30 females), in a Singapore mangrove patch with an intermediate resource level. As the semiterrestrial intertidal crabs can only forage after emergence from their burrows during exposure period, the duration of time available for feeding is finite and constitutes an important constraint in the optimization of food intake. The activity budget (in terms of time spent on feeding activities, all above-ground non-feeding activities, and burrow-sequestration) as well as the occurrence (if any) of larder hoarding behavior in these two species after they first emerged were recorded by hourly intervals (three hours of observation) to determine the effect of time left for foraging on larder hoarding. Regardless of species, A. annulipes and G. vocans spent most of the time feeding when the tide was out, despite overall significant behavioral heterogeneity (multivariate analyses using ANOSIM) indicating that both species prioritized hunger satiation over other activities. Our results also showed that although the two sympatric crabs live in the same mangrove area with similar food resource levels, only A. annulipes larder hoarded. The propensity to larder hoard did not differ significantly between the sexes, nor among the three time periods of the feeding duration. Gelasimus vocans, one of the species of crabs known to form feeding droves, did not larder hoard at all. We propose that A. annulipes is a species that can deploy larder hoarding as a foraging strategy when it encounters valuable food resources, and such a strategy is highly advantageous for the species as it generally inhabits sandy habitats that are poor in nutrient levels. Hence, larder hoarding can be considered a mixed evolutionarily stable strategy (ESS) adopted by A. annulipes. In contrast, G. vocans that commonly inhabits muddy sediments—with a high level of food resources—did not larder hoard, even when provided with supplemented food, suggesting perhaps that its mixed ESS is droving behavior.

Density and distribution patterns of two species of fiddler crabs, Uca annulipes (H. Milne Edwards, 1837) and U. vocans (Linnacus, 1758) were studied on Palau [=Island] Hantu Besar, Singapore. Twenty-five and 261 m2 quadrats were sampled at the upper and lower shore levels of the lagoonal beach. Sediment samples from each quadrat were analysed for %sand, %mud and %organic content. A two-way analysis of variance (ANOVA) of crab density against species and shore level position showed the interaction term. 'Species X Shore level' to be significant (p<0.05), with Uca annulipes being more abundant on the upper shore and U. vocans preferring the lower shore. A General Linear Model for Multivariate Analysis of Variance (MANOVA) was used to further analysed the biotope-related variables (sand, mud and organic content) against crab species and shore level position. This time 'Species X Shore level' interaction was not significant (p>0.05). After this interaction term was removed from the model, only the main factor, 'Species', was significant (p<0.05). Subsequent ANOVAs showed U. annulipes was significantly (p<0.05) associated with sediments containing higher sand content regardless of shore level, and U. vocans was significantly (p<0.05) associated with sediments that had higher mud content. These results provide quantitative data to support and explain qualitative observations that U. annulipes are generally found in sandier habitats than U. vocans.

An oil spill occurred in the Straits of Singapore (one of the world’s busiest shipping lanes) on 25 May 2010. Pre- and post-oil spill population parameters (i.e., abundances, densities, burrow diameters, location of burrows with respect to shore height and size-distribution gradient) of the ghost crab Ocypode ceratophthalmus on two adjacent beaches at East Coast Park, Singapore, were compared to study the extent of impact and subsequent recovery rate. The ghost crab population, which was decimated after the oil spill, rebounded within three months to densities close to those that were observed prior to the oil spill. The lower boundary of the recolonised population in September 2010 and January 2011 shifted upshore by about 0.4 m from that documented in September 2006. The zone that was recolonised was between 2.6 m and 2.8 m above Chart Datum in January 2011, directly above the upper limit of the region contacted by the spilled oil, indicating that the crabs avoided settling in sediments that contained oil residues. No distinct size distribution gradient on the shore was observed in the pre- and postspill populations. This study confirms that the abundance and distribution of O. ceratophthalmus provide reliable, sensitive and effective indications of the conditions of beach habitats.

The functional morphology of maxilliped-setation in three species of fiddler crabs—Petruca panamensis, Leptuca terpsichores and L. beebei— collected from Panama were studied using a comparative ecomorphological approach. The coverage of spoon-tipped (ST) and plumose (P) setae on the inner surface of the second maxilliped were noted, and the abundance of each setal type was enumerated, with crab carapace width as the covariate. These attributes were then related to the sediment particle size characterization of their respective collection sites for an ecomorphological comparison. All three species have mixed setation, albeit in different proportions of coverage. For L. terpsichores, the ST:P coverage was consistently ca. 70%:30% whereas there was approximately equal coverage of both setal types (i.e., 50% ST:50% P) on the maxillipeds of L. beebei and P. panamensis. Analysis of Covariance (ANCOVA) results of setal counts between the sexes in each species showed that the number of ST and P setae did not differ significantly between males and females, indicating an absence of sexual dimorphism in mouthpart setae. When all three species were compared—sexes combined within each species— ANCOVA results reveal that for any crab of a given size, there were significantly more ST setae on the second maxilliped of L. terpsichores (sediment from sampling site classified as ‘moderately-sorted medium sand’) than L. beebei (sediment from sampling site classified as ‘moderately-sorted fine sand’) and P. panamensis (a rocky-habitat species); no significant difference was detected between ST abundance in the latter two species. Current results provide unequivocal quantitative evidence that the abundance of ST setae can be an indicator to differentiate habitats down to the level of different sand-grain size, i.e., medium sand versus fine sand habitats of L. terpsichores and L. beebei, respectively. Both L. beebei and P. panamensis had significantly fewer ST setae than L. terpsichores, possibly because the former two species’ habitats have sediments with sand grains that are less coarse than the latter’s. On rocks, P. panamensis does not produce pseudofecal pellets as they directly swallow food materials pinched from the rock surfaces without sorting, rendering the role of ST setae of secondary importance. The three species did not differ significantly in P setae abundance, suggesting that the adaptive function of this type of setae to habitat characteristics remains debatable. The significance of ST setae as an ecomorphological adaptation for efficient food extraction from sandy sediments is, thus, evident in L. terpsichores. As for other two species—L. beebei and P. panamensis—that live in environments with finer sediment grain sizes, the adaptive role of ST setae is of diminished functional importance. Fiddler crab species with mixed setal types may have greater potential to exhibit feeding plasticity should their habitats be threatened.

This report details the three keys aspects of the project ─ (a) the ideas and motivation of teachers to carry out inquiry, (b) students ideas about science learning in school, and (c) factors that could enhance science teacher professional development to carry out inquiry. In elementary science classrooms, we showed that: (1) while teachers express moderate to strong intention to teach science through inquiry they are constrained by numerous components in their classroom context, including goals of instruction, curriculum integration, learning environment, lesson strategies, student disposition and teacher disposition; (2) students value hands-on and collaborative experiences for learning science, suggesting a pedagogy characterized by clear learning goals and valuing a sense of community among learners; and (3) further training should focus on how to, more than why, teach through inquiry, adopting a paradigm that is responsive to different contexts.

In this paper, we characterize the inquiry practices of four elementary school teachers by means of a pedagogical framework. Our study surfaced core components of inquiry found in theoretically-driven models as well as practices that were regarded as integral to the success of day-to-day science teaching in Singapore. This approach towards describing actual science inquiry practices - a surprisingly neglected area - uncovered nuances in teacher instructions that can impact inquiry-based lessons as well as contribute to a practice-oriented perspective of science teaching. In particular, we found that these teachers attached importance to (a) preparing students for investigations, both cognitively and procedurally; (b) iterating pedagogical components where helping students understand and construct concepts did not follow a planned linear path but involved continuous monitoring for learning; and (c) synthesizing concepts in a consolidation phase. Our findings underscore the dialectical relationship between practice-oriented knowledge and theoretical conceptions of teaching/learning thereby helping educators better appreciate how teachers adapt inquiry science for different contexts.

The agamid genus Bronchocela is represented by seven species distributed in the southeastern corner of South Asia, the Sundaland, the Lesser SundaIslands, Sulawesi, Philippines, and the Moluccan islands and northwest New-Guinea east of the Lydekker's Line. The taxonomic status of Bronchocela cristatella, once considered a member of the speciose genus Calotes, is reviewed. Egg shape and the ratio of tail length to snout-vent length are two characters that are useful to delimit the genus Bronchocela from other agamid genera allied to it. Of 10 morphometric variables studied in 32 museum specimens, tail length (TL) and snout-vent length (SVL) were the main variables which accounted for body size and shape variation respectively. No sexual dimorphism for body size and shape was detected. Bronchocela cristatella, like other members in the genus, has the longest tail among arboreal agamids. A diagnosis for the species is proposed.