Estuarine Macrophytes at Bakkhali, Cox’s Bazar, Bangladesh with Reference to Mangrove Diversity

The diversity and ecosystem significance of macrophyte communities was studied, with emphasis on the mangrove species in the Bakkhali estuary of Cox’s Bazar, Bangladesh. Macrophytes of the Bakkhali river estuary were mainly mangroves (Avicennia marina Forssk Vierh and A. alba Blume and Acanthus ilicifolius Linnaeus) of inundation Class-IV; i.e., the mangroves are inundated 2-20 times per month (Watson, 1928), a wild rice variety of salt marsh (Porteresia coarctata Tateoka), Congon grass (Imperata cylindrica P. Beauv.), seagrass (Halophila beccarii Ascherson), macro-algae (Ulva intestinalis Linnaeus, Catenella nipae Zanardini and Hypnea sp.) and mangrove associates Suaeda maritima Only two individual plants of mangrove, Sonneratia apetala and Aegialitis rotundifolia, were found growing in the inter-tidal area of this estuary. On the eastern side of the estuary, almost 100% of the intertidal area is covered by the salt marsh plant P. coarctata, with patches of seagrass Halophila beccarii. The western portion of the estuary is covered by mangroves, mixed with patchy salt marsh and seagrass in and sheltered by a sand bar. Salt marsh and seagrass grow in mangrove dominated sites as 2nd pioneer species in the newly accreted land at the mouth of Bakkhali estuary. These estuarine macrophytes are of both economic and ecological significance and the macrophyte community plays a principal role directly or indirectly in supporting the local communities as source of food, cash and energy

Antibacterial activities of selected seaweed and seagrass from Port Dickson Coastal Water against different aquaculture pathogens

Eight seaweed species in Teluk Kemang and three seagrass species in Teluk Pelanduk, Port Dickson, respectively, were screened for antibacterial activities. The antibacterial activities were screened using disc diffusion test, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against six aquacultural pathogens strains Aeromonas hydrophila ATCC35654, Vibrio harveyi BB120, Vibrio harveyi ATCC14126, Vibrio alginolyticus ATCC17749, Vibrio parahaemolyticus ATCC17803 and Vibrio anguillarum ATCC43313. The results showed that among all the pathogens, seaweed Padina minor and seagrass Thalassia hemprichii had the strongest antibacterial activity against Vibrio harveyi BB120 and Vibrio harveyi ATCC14126, respectively. The lowest values for minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were obtained from Padina minor against V. harveyi BB120 and Thalassia hemprichii against V. harveyi ATCC14126, respectively. The findings suggested that seaweed and seagrass in Port Dickson coastal water have the potential to prevent bacterial diseases particularly in aquaculture

Morphological characteristics, shoot density and biomass variability of Halophila sp. in a coastal lagoon of the east coast of Malaysia

This study in a coastal lagoon of Merchang Terengganu, east coast of Peninsular Malaysia evaluated the morphological characteristics, shoot density and biomass for Halophila in pure and mixed population with Halodule pinifolia (Miki) den Hartog. Both species inhabited the silt and sand substrates at depth of about 1.9 m to 2.0 m. They are well adapted and tolerated a range of micro-ecology; pH of 6.57-7.32, wide salinity differences of 9.42-34.47 psu, conductivity 16.14-52.27 ms/cm, and light availability of 446.63-624.1 lux. Morphologically, there are two forms for Halophila (a) small-leaved in pure population and those mixed with the short-leaved, (b) big-leaved with the long-leaved Halodule pinifolia. Both forms have variable leaf shapes, a respond to the wide and frequent fluctuation in water salinity. Leaves possessed red or purplish spots or blotches with more spots and blotches in leaves of Halophila in pure population. These spots or blotches are believed to be UV-blocking pigments for protection of plants exposed directly to strong sun-light during low tides. Shoot density of 79.08±38.02 shoots/100cm2; is comparatively higher in pure Halophila population compared with 26.33±13.20 shoots/100cm2 and 64.00±17.09 shoots/100cm2 for small-leaved and big-leaved Halophila sp. respectively. Halophila biomass (AG and BG) exhibit similar trend as those observed for shoot density. In pure or mixed Halophila population the majority of the biomasses (63-77% of the total) were in the belowground parts (rhizome and roots). Although Halophila sp. is a smaller size seagrass, for propagation they would need extensive rhizome networks buried in the substrates.Proceedings of 4th JSPS-VAST Joint Seminar on \u27Coastal Marine Science\u27, Hai Phong, Viet Nam, 26-28 October 2009Oceanograph

Changes in macroalgae species composition, assemblage and coverage at an inter-tidal rocky shore

Samplings of macroalgae were undertaken at an inter-tidal rocky shore of Kuala Similajau (Lat. 3°22′ 13.9′N, Long. 113°17′ 39.1″E), Bintulu, Sarawak during two peaks of wet period; Feb.-Mar. (monthly total rainfall of 514.0 mm, 481.6 mm; average temperature 25.7℃, 26.2℃) and Jul.-Aug. (monthly total rainfall 585.8 mm, 566.2 mm; average temperature 26.3℃, 27.0℃) 2008. This study investigates the changes in macroalgae species composition, assemblage and coverage covering the two peaks of wet period. A total of 23 taxa comprising 7 green, 5 brown and 11 red algae were recorded covering the two peaks of wet period, with red algae being the most diverse division. Comparatively a lower number of macroalgae species occurred during Feb.-Mar. (12 species) compared to the period of Jul.-Aug. (20 species). Several species such as Ulva clathrata (Roth) Greville, Valonia aegagropila C. Agardh and Lobophora variegata (Lamouroux) Womersley ex Oliveira, were absent during the Feb.-Mar. Common species Anadyomene plicata C. Agardh, Sargassum sp., Acanthophora spicifera (Vahl) Borgesen, Amphiroa fragilissima (Linnaeus) Lamouroux, Gelidiella acerosa (Forsskal) Feldmann & Hamel, Gracilaria salicornia (C. Agardh) Dawson, Hydropuntia edulis (S. G. Gmelin) P. C. Silva, Laurencia papillosa (C. Agardh) Greville and Laurencia sp. were present in both periods. Acetabularia major C. Agardh, Cladophora prolifera (Roth) Kutzing, Ulva intestinalis (Linnaeus) Nees, Padina minor Yamada, Ceramium sp. and Pterocladia sp. were only present in the Jul.-Aug. In terms of mean coverage, there is no distinct trend in domination with respect to a particular species between the two peaks of wet period. However, based on the number of mean coverage contributed by the species, categorically this can be represented as Division Rhodophyta>Division Chlorophyta>Division Phaeophyta.Proceedings of 4th JSPS-VAST Joint Seminar on 'Coastal Marine Science', Hai Phong, Viet Nam, 26-28 October 2009Oceanograph

Changes in macroalgae species composition, assemblage and coverage at an inter-tidal rocky shore

Samplings of macroalgae were undertaken at an inter-tidal rocky shore of Kuala Similajau (Lat. 3°22′ 13.9′N, Long. 113°17′ 39.1″E), Bintulu, Sarawak during two peaks of wet period; Feb.-Mar. (monthly total rainfall of 514.0 mm, 481.6 mm; average temperature 25.7℃, 26.2℃) and Jul.-Aug. (monthly total rainfall 585.8 mm, 566.2 mm; average temperature 26.3℃, 27.0℃) 2008. This study investigates the changes in macroalgae species composition, assemblage and coverage covering the two peaks of wet period. A total of 23 taxa comprising 7 green, 5 brown and 11 red algae were recorded covering the two peaks of wet period, with red algae being the most diverse division. Comparatively a lower number of macroalgae species occurred during Feb.-Mar. (12 species) compared to the period of Jul.-Aug. (20 species). Several species such as Ulva clathrata (Roth) Greville, Valonia aegagropila C. Agardh and Lobophora variegata (Lamouroux) Womersley ex Oliveira, were absent during the Feb.-Mar. Common species Anadyomene plicata C. Agardh, Sargassum sp., Acanthophora spicifera (Vahl) Borgesen, Amphiroa fragilissima (Linnaeus) Lamouroux, Gelidiella acerosa (Forsskal) Feldmann & Hamel, Gracilaria salicornia (C. Agardh) Dawson, Hydropuntia edulis (S. G. Gmelin) P. C. Silva, Laurencia papillosa (C. Agardh) Greville and Laurencia sp. were present in both periods. Acetabularia major C. Agardh, Cladophora prolifera (Roth) Kutzing, Ulva intestinalis (Linnaeus) Nees, Padina minor Yamada, Ceramium sp. and Pterocladia sp. were only present in the Jul.-Aug. In terms of mean coverage, there is no distinct trend in domination with respect to a particular species between the two peaks of wet period. However, based on the number of mean coverage contributed by the species, categorically this can be represented as Division Rhodophyta>Division Chlorophyta>Division Phaeophyta.Proceedings of 4th JSPS-VAST Joint Seminar on \u27Coastal Marine Science\u27, Hai Phong, Viet Nam, 26-28 October 2009Oceanograph

Landsat image enhancement techniques for subtidal and intertidal seagrass detection and distribution mapping in the coastal waters of Sungai Pulai estuary, Malaysia

In Malaysia, seagrasses commonly inhabit shallow intertidal waters, semi enclosed lagoons, mangroves, coral reef flats and shoals in subtidal zones. Seagrass meadows have widely been surveyed by field sampling methods. As an alternative means to field-based surveys, airborne and/or satellite based sensors have been used to produce cost-effective and, more importantly, repetitive sources of information on seagrass distribution over wider areas. The satellite-based sensors Landsat imagery have been used as relatively economic alternatives to aerial photographs to produce seagrass cover maps and change analysis. Two radiometric image enhancement techniques (ETs)?histogram equalization (HE) and manual enhancement (ME) were applied on the series of Landsat images for comparative analysis and assessing ability of ETs to recognize seagrass meadows within the subtidal and intertidal coastal waters of the Sungai Pulai estuary, Johor Straits, Malaysia. With a view to find relations between Mean Sea Level Tide Heights (MSLTHs) and results of ETs, actual 33 multi-date (1989?2014) images with a wide range of MSLTH regimes (-0.281 to 0.234 m) during image acquisition time, were processed by applying ETs. The ME substantially improved image quality compared to the HE, enabled detection of Seluyong seagrass meadows in intertidal mudflat, Merambong, Tanjung Adang Darat, Tanjung Adang Laut shoals in the subtidal areas. Seagrass meadows were \u27eeasy-to-recognize\u27without noticeable variations due to MSLTH differences from the enhanced images acquired during extreme lowest spring tide height, -0.218 m and above until MSLTH at -0.085 m; found \u27difficult-to-recognize\u27at full extent between ?0.067 to -0.003 m and \u27not-recognizable\u27above MSLTH. ETs would be ineffective if applied to images acquired higher than MSLTH (0.007 to 0.234 m). The proposed ET is found to provide a consistent and quantitative areal cover for seagrass mapping and understand past changes from multi-date image analyses