Muta Harah Zakaria

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.

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.

Suitability of Aquatic Plant Fibers for Handmade Papermaking

Increasing concerns for future fiber supplies in pulp and paper industries has shifted interest in nonwood sources from agriculture residues and aquatic plants. Aquatic plants with short growth cycles, in abundance, and with low lignin are a potential fiber source. Five aquatic plant species, Cyperus digitatus, Cyperus halpan, Cyperus rotundus, Scirpus grossus, and Typha angustifolia, were examined for fiber dimensions and chemical composition (cellulose, lignin) and compared with other nonwood plants. All aquatic plants possessed short (length, 0.71–0.83 mm) and thin (diameter, 9.13–12.11 µm) fibers, narrow lumen (diameter, 4.32–7.30 µm), and thin cell wall (thickness, 2.25–2.83 µm) compared with most other nonwood plants. Slenderness ratio ranged from 73.77 to 89.34 with Typha angustifolia having the highest ratio. Except for Scirpus grossus, the flexibility coefficient ranged from 52.91 to 58.08. Scirpus grossus has low Runkel ratio, 0.84 ± 0.17. Fiber characteristics, short and thin fibers, Slenderness ratio >60, flexibility coefficient within 50–75, and Runkel ratio 34% is suitable for pulp and papermaking. Lignin content in aquatic plants in the present study ranged 9.54–20.04% and below the wood lignin content of <23–30% encountered in pulp and papermaking. Handmade paper sheets produced for paperboard, craft, and decorative purposes are with permissible tensile strength, breaking length, and low moisture content.

Fiber characteristics in tropical aquatic plants for handmade papermaking

This study was performed to explore aquatic plants potential as raw materials to be used as alternative fibers in papermaking. Aquatic plants; Eleocharis dulcis, Limnocharis flava, Nymphaea nouchali, Blyxa aubertii and Cyperus malaccensis were collected from wetland areas and used as raw materials for handmade papermaking. Variables include; cell wall thickness, fiber diameter, lumen diameter and fiber length were examined and measured. Nymphaea nouchali possessed comparatively longer fiber length (0.571 mm), wider fiber diameter (48.17 μm) and lumen diameter (38.46 μm). Cyperus malaccensis has shorter fiber length (0.093 mm) and B. aubertii has narrower fiber diameter (16.1 μm) and cell wall thickness (3.77 μm). With respect to slenderness ratio (index to determine the strength of paper), B. aubertii possessed higher slenderness ratio of 16.4. All the species examined in this study have less than one Runkel ratio except for L. flava. Flexibility coefficient for the species evaluated ranged between 40.90–80.06%. Cyperus malaccensis, B. aubertii and N. nouchali have flexibility coefficient within standard range for papermaking suitability which were 53.8%, 61.78% and 80.06%, respectively. The slenderness ratio, Runkel ratio and flexibility coefficient characteristics contribute to tissue stability and have effect on the properties of handmade paper. Fiber distribution in produced paper sheets varied from random to uniform distribution. Limnocharis flava have higher shrinkage rate (11.43%) compared to other species whereas C. malaccensis possessed lowest shrinkage rate (3.93%).