Japar Sidik Bujang

Distribution and significance of seagrass ecosystems in Malaysia

Seagrasses are the only flowering plants (monocotyledonous Angiosperms) that have adapted themselves to living in marine and estuarine habitats, and are submerged most of the time. They are rooted in sediments on the sea bottom, with shoots appearing above the substrate. Seagrasses occurred at 78 sites scattered in the west and east coasts of Peninsular Malaysia and in Sabah and Sarawak in East Malaysia. They are usually found along the coasts growing in association with shallow inter-tidal, mangroves, coral reefs, semi-enclosed lagoons and shoals. In these habitats, seagrass beds or meadows have distinct species assemblage completely adapted to the submerged life. There are fourteen major species of seagrasses recorded in Malaysia: Enhalus acoroides, Halophila beccarii, H. decipiens, H. ovalis, H. minor, H. spinulosa, Halodule pinifolia, H. uninervis, Cymodocea rotundata, C. serrulata, Thalassia hemprichii, Syringodium isoetifolium, Ruppia maritima and Thalassodendron ciliatum. Although seagrasses make up only a small portion of the marine ecosystem, the physical settings and their interactive community within and from outside account for their high diversity and ensure survival of an assortment of vertebrates (fish), invertebrates (shrimps, starfish, sea cucumbers, bivalves, gastropods), and seaweeds. Seagrass form the food and habitats for the vulnerable dugongs or sea cows (Dugong dugon), seahorses (Hippocampus spp.) and endangered green turtles (Chelonia mydas), and for other fish, and also a feeding ground for seasonal migratory birds, Egretta garzetta. Seagrasses provide conditions for the growth and abundance of invertebrates and fish that many local coastal communities collect and catch for their livelihood. Seagrass ecosystems are sources of food and yet they are continually threatened by human activities, causing their degradation and possible habitat loss. The purpose of this review is to give information on the significant linkages of seagrasses with the coastal inhabitants and to suggest recommendations for the protection and conservation of this important ecosystem and the associated resources.

The application of remote sensing to seagrass ecosystems: an overview and future research prospects

This review evaluates various methods employed to produce seagrass habitat maps using optical and acoustic remote-sensing (RS) techniques coupled with in situ sampling to highlight recent advances and to define areas where potential future research should be focused in the application of RS technologies. A critical review of 195 studies revealed that, in the past four decades, advances in the application of RS methods, notably using Landsat imagery, are identified for seagrass detection, assessment of areal coverage, distribution and abundance mapping, and the detection of extent and biomass changes, as illustrated in peer-reviewed literature. Rapid technological and methodological advances have occurred in the acquisition and interpretation of optical and acoustic data for the mapping of seagrass habitats. The methods have been tested to segment, classify, and combine RS data with biological field or ground truth sample data. There is no single technology or approach that is suitable for and capable of measuring all seagrass parameters (presence/absence, cover, species, and biomass) and assessing change. Integration of field, imagery, and mapping approaches is therefore required. Further research is required for continued improvements in understanding of theoretical and methodological aspects of seagrass RS.

The architecture and allometry of mangrove saplings

1. The architecture and allometry of eight populations of mangrove tree saplings of seven species (1.5-3 m in height) were studied at Sungei Merbok, Kedah, Peninsular Malaysia. Three populations (Bruguiera cylindrica, Bruguiera parvilfora and Rhizophora apiculata) were growing in shaded conditions, the other five (Avicennia alba, Rhizophora apiculata, Rhizophora mucronata, Sonneratia alba and Xylocarpus granatum) were in the open. 2. Comparisons were made between the population specific allometric regressions for dimension pairs of the form ln γ=b 1 ln x+b 0 . The bifurcation ratio (R b ) for the-branching system of each sapling was calculated. 3. In the majority of the allometric regressions the populations differed significantly in b 0 but not b 1 , though some significant slope differences were found, particularly for regressions involving root dry weight. 4. The allometric analysis showed that for saplings of the same height, those growing in the shade had lower shoot dry weight and lower dry weight and area of leaves than the open-grown ones. The shaded saplings also exhibited a greater accumulation of foliage at the top of the plant. 5. Xylocarpus granatum was notable for a low investment in leaves, which was probably explained by recent flushing, and in roots, which may reflect the limited development of pneumatophores in this species. The shaded Bruguiera populations showed a relatively high root investment probably because of their abundant pneumatophore development. 6. When compared to published results of allometric analyses for shaded saplings from lowland tropical rain forest and warm temperate rain forest it was found that the shaded mangroves were consistently more similar to the unshaded mangroves than to the rainforest saplings. This may be because the shaded mangroves were growing under higher average irradiances than those from the rain forests. It is argued, however, that mangrove species are inherently more likely to show an architecture better suited to high irradiance conditions than the majority of broad-leaved evergreen rain-forest trees

Sugars, ascorbic acid, total phenolic content and total antioxidant activity in passion fruit (Passiflora) cultivars

BACKGROUND The levels of sugars, ascorbic acid, total phenolic content (TPC) and total antioxidant activity (TAA) were determined in fruit juices from seven passion fruit (Passiflora spp.) cultivars: P. edulis cultivars Purple, Frederick, Yellow, Pink, P. edulis f. flavicarpa, P. maliformis and P. quadrangularis (we also tested this cultivars mesocarp). RESULTS Purple and Yellow P. edulis had significantly higher total sugar, 142.85 ± 0.17 g kg⁻¹ and 139.69 ± 0.12 g kg⁻¹, respectively, than other cultivars. Glucose and fructose content were higher in juice from vine-ripened fruits of Purple, Frederick and Yellow P. edulis, P. quadrangularis and P. maliformis. Sucrose content was significantly higher in juice of non-vine-ripened fruits of P. edulis (Pink) and P. edulis f. flavicarpa. Ascorbic acid, TPC and TAA were significantly higher in vine-ripened Purple and Yellow P. edulis; ranges were 0.22-0.33 g kg⁻¹, 342.80-382.00 mg gallic acid equivalent L⁻¹ and 409.13-586.70 µmol Trolox L⁻¹, respectively. Based on principal component analysis (PCA) and cluster analysis, the main variables - °Brix, total sugar, glucose, fructose, ascorbic acid, TPC and TAA - formed the characteristics for the group comprising Purple and Yellow P. edulis. CONCLUSIONS Glucose, fructose, sucrose, ascorbic acid, TAA and TPC were quantified in passion fruit juices. Variation of the above variables in juices of Passiflora depends on the cultivar and ripeness.

Assessment of Total Phenolic, Antioxidant, and Antibacterial Activities of Passiflora Species

This study focused on total phenolic content (TPC) and antioxidant and antibacterial activities of the leaves and stems of Passiflora quadrangularis, P. maliformis, and P. edulis extracted using three solvents: petroleum ether, acetone, and methanol. The maximum extraction yields of antioxidant components from the leaves and stems were isolated using methanol extracts of P. edulis (24.28%) and P. quadrangularis (9.76%), respectively. Among the leaf extracts, the methanol extract of P. maliformis had the significantly highest TPC and the strongest antioxidant activity, whereas among the stem extracts, the methanol extract of P. quadrangularis showed the highest phenolic amount and possessed the strongest antioxidant activity. The antibacterial properties of the Passiflora species were tested using the disc diffusion method against 10 human pathogenic bacteria. The largest inhibition zone was observed for the methanol extract of P. maliformis against B. subtilis. Generally, extracts from the Passiflora species exhibit distinct inhibition against Gram-positive but not Gram-negative bacteria. Based on the generated biplot, three clusters of bacteria were designated according to their performance towards the tested extracts. The present study revealed that methanol extracts of the Passiflora contain constituents with significant phenolic, antioxidant, and antibacterial properties for pharmaceutical and nutraceutical uses.

Assessment of Landsat 7 Scan Line Corrector-off data gap-filling methods for seagrass distribution mapping

Methods to predict and fill Landsat 7 Scan Line Corrector (SLC)-off data gaps are diverse and their usability is case specific. An appropriate gap-filling method that can be used for seagrass mapping applications has not been proposed previously. This study compared gap-filling methods for filling SLC-off data gaps with images acquired from different dates at similar mean sea-level tide heights, covering the Sungai Pulai estuary area inhabited by seagrass meadows in southern Peninsular Malaysia. To assess the geometric and radiometric fidelity of the recovered pixels, three potential gap-filling methods were examined: (a) geostatistical neighbourhood similar pixel interpolator (GNSPI); (b) weighted linear regression (WLR) algorithm integrated with the Laplacian prior regularization method; and (c) the local linear histogram matching method. These three methods were applied to simulated and original SLC-off images. Statistical measures for the recovered images showed that GNSPI can predict data gaps over the seagrass, non-seagrass/water body, and mudflat site classes with greater accuracy than the other two methods. For optimal performance of the GNSPI algorithm, cloud and shadow in the primary and auxiliary images had to be removed by cloud removal methods prior to filling data gaps. The gap-filled imagery assessed in this study produced reliable seagrass distribution maps and should help with the detection of spatiotemporal changes of seagrasses from multi-temporal Landsat imagery. The proposed gap-filling method can thus improve the usefulness of Landsat 7 ETM+ SLC-off images in seagrass applications.

Genetic Diversity in Passiflora Species Assessed by Morphological and ITS Sequence Analysis

This study used morphological characterization and phylogenetic analysis of the internal transcribed spacer (ITS) region of nuclear ribosomal DNA to investigate the phylogeny of Passiflora species. The samples were collected from various regions of East Malaysia, and discriminant function analysis based on linear combinations of morphological variables was used to classify the Passiflora species. The biplots generated five distinct groups discriminated by morphological variables. The group consisted of cultivars of P. edulis with high levels of genetic similarity; in contrast, P. foetida was highly divergent from other species in the morphological biplots. The final dataset of aligned sequences from nine studied Passiflora accessions and 30 other individuals obtained from GenBank database (NCBI) yielded one most parsimonious tree with two strongly supported clades. Maximum parsimony (MP) tree showed the phylogenetic relationships within this subgenus Passiflora support the classification at the series level. The constructed phylogenic tree also confirmed the divergence of P. foetida from all other species and the closeness of wild and cultivated species. The phylogenetic relationships were consistent with results of morphological assessments. The results of this study indicate that ITS region analysis represents a useful tool for evaluating genetic diversity in Passiflora at the species level.

Habitat preference and usage of Strombus canarium Linnaeus, 1758 (Gastropoda: Strombidae) in Malaysian seagrass beds

Abstract Despite their economic importance, the ecology of Strombus canarium is poorly understood and factors influencing their habitat preferences remain largely unexplained. The species was reported as highly associated with seagrass bed ecosystems, but their distribution and specific preferences within the habitat remain unknown. Determining the mechanisms that regulate conch distribution and abundance is of fundamental importance for management of the species. In this study habitat preference and usage of conch in their natural habitat were investigated. The population was patchily distributed and present in local colonies that comprised of mixed age groups. There was high spatial variation in conch abundance, where multivariate analysis (PCA) showed high preferences for microhabitat with mixed seagrasses dominated by Halophila spp. Other important habitat characteristics preferred were high sediment organic content (% LOI), high sediment sorting (φ), and low mean sediment particulate size. Areas with dense Enhalus acoroides meadows, though in many reports have been linked with the species, were surprisingly the least preferred microhabitat. It is concluded that the preference towards specific microhabitat within the seagrass bed is associated with their feeding, and intra-specific interactions among individuals.

Regional Comparison of the Ecosystem Services from Seagrass Beds in Asia

Coastal ecosystems offer valuable services to human society. However, these ecosystems are facing multiple impacts of human-induced stress, including overexploitation, eutrophication, land construction, and global climate change. The prediction of long-term changes in coastal ecosystems under multiple impacts is difficult because nonlinear and cumulative effects operate simultaneously. This difficulty is especially true for Asian regions, where coastal biodiversity is the world’s highest but the least studied. In this chapter, we compare ecosystem services of coastal areas of Asia based on the expert knowledge of practioners who study coastal ecosystems at each locality. We especially focused on seagrass beds, which provide important services to humans including provision of seafood and regulation of water conditions. We selected the six most important ecosystem services at each of 13 seagrass beds ranging from Japan to India and evaluated the direction of changes over the past two decades. We also evaluated public awareness and data certainty for each service. Food provisioning, water purification and waste treatment, erosion regulation, recreation and ecotourism, and educational values were selected as major ecosystem services of seagrass beds. Degradation during the over past 10–20 years was reported for most provisioning and regulating services, whereas improving trend was found for cultural services in most sites. Public awareness and certainty of information were generally high for provisioning services, but low for most regulating services. Regional variation along latitude, and differences between temperate and tropical seagrass beds, were not detected for the examined variables. Regional comparisons of ecosystem services shed light on general and specific aspects of the status of seagrass beds, which will provide baseline data for planning effective conservation and management strategies under multiple human impacts.

Description and evaluation of imposex in Strombus canarium Linnaeus, 1758 (Gastropoda, Strombidae): a potential bio-indicator of tributyltin pollution

Strombus canarium Linnaeus, 1758 is an important gastropod species within the study area and was traditionally collected for food by the locals. The objective of the present study is to assess the incidence of imposex and its severity in this species. Adult conchs were sampled during their main reproductive period, from October 2005 to January 2006, at Sungai Pulai estuary, Johor Straits, Malaysia. A total of 32.81% of adult females showed imposex characteristics, with varying degrees of severity though. The relative penis size (RPS) index ranged from 1.74 to 33.29 (mean = 13.40 ± 2.27, n = 21), while the relative penis length (RPL) index ranged from 6.28 to 55.19 (mean = 25.83 ± 3.33, n = 21). The use of vas deferens sequence (VDS) index was however cannot be applied as the presence of egg groove obscured any vas deferens development in affected females. Sequence of imposex (male penis) development in female conch, from merely a small stump to an advance male penis homologous was therefore carefully analyzed and described, and an alternative imposex classification scheme was proposed. S. canarium can be a good indicator for monitoring of organotin pollution within the study area. However, more studies are needed in order to further develop and test its validity and application, such as its correlation with levels of pollutant within the tissues and the environment, as well as its application on other Strombus species.