Volume 3, Issue 2 (4-2001)
Abstract
In the first experiment, twelve species of the most plentiful and fresh seaweeds and one
species of seagrass from the beach were collected at Kingston, South Australia. All species
were then separately sun-and oven-dried and ground. The ground samples were analysed
for dry matter, ash, organic matter, crude protein, crude fibers, ether extract and digestibility
in vitro. The digestible and metabolisable energy of the samples were estimated by
calculation. The results showed that all seaweeds and seagrasses contained a very high ash
content, ranging from 19.5 - 40 per cent. The crude protein content of the samples was
low and ranged from 4.4 - 7.3 per cent. The crude fiber in seagrass was considerably
greater than in seaweed species (34.4 % vs 3.7 -10.1 %). The dry matter digestibility of
samples ranged from 34.1 to 51.5, while the data also showed that the values for digestible
and metabolisable energy of aquatic plants were very low as compared with lucerne (the
control). From the first experiment it was concluded that, amongst marine plants available
in South Australia, the seagrass Posidonia australis, because of its ready availability
in great quantities and the environmental problems for residents, may be regarded as a
potential alternative animal feedstuff. In the second experiment, samples of four different
physical forms of seagrass, Posidonia australis green and fresh (from the water, and
washed and un-washed from on the beach) were examined and compared for their chemical
composition, including nonstarch-polysaccharides, uronic acids, neutral detergent fiber,
acid detergent fiber and lignin, amino acids, crude protein, tannin, ether extract,
soluble and insoluble ash. The results from this experiment showed that there were no
significant differences between the four different physical forms of seagrass collected in
terms of their most important chemical constituents.
Mehdi Tabarsa, , ,
Volume 5, Issue 1 (6-2016)
Abstract
Extracted polysaccharides from green seaweeds are heterogeneous in structural and molecular properties. Basically, sulfated polysaccharides from green seaweeds contain various amounts of rhamnose (16.5-45.0%), xylose (2.1-12.0%), glucose (0.5-6.4%) and sulfate (16.0-23.2%), and their building blocks are chiefly comprised of β-D-GlcpA-(1 → 4)α-L-Rhap3s. Molecular weight of sulfated polysaccharides varies from 93.4 × 103 to 1690 × 103 g/mol. The biological effects of seaweed sulfated polysaccharides are immunomodulation, cancer cell growth suppression, antioxidation, antihyperlipidemic, antiviral and anticoagulation. As the chemical structure and molecular properties of sulfated polysaccharides differ from one seaweed species to another, the biological properties varies subsequently. Overall, given the fact that highly variable marine environment can significantly incorporate into the existing discrepancies of sulfated polysaccharide structures due to seaweed phylogenetic differences, executing more comprehensive studies on various species is necessary to have a better understanding of their function and future applications
Volume 10, Issue 3 (10-2022)
Abstract
Aims: Monitoring variations in macroalgal assemblages is a crucial issue for the preservation and management program of coastal waters. This study was conducted to determine the seasonal and spatial distribution patterns, and composition of macroalgal communities along the eastern coasts of Qeshm Island, Iran.
Materials & methods: Seasonal sampling was conducted at three different sites of different tidal levels on the eastern coasts of Qeshm Island. Random samples of macroalgae were collected at three stations, seasonally. The species were identified and the dry weight of each species was used to calculate the macroalgae abundance. The Species richness and the Diversity indices were calculated to evaluate the distribution pattern and composition of the macroalgal community.
Findings: As a result, 51 species (4 Chlorophyta, 21 Phaeophyta, and 26 Rhodophyta) were identified. The seasonal and spatial dominant species were found to be Padina sp. and Hypnea sp., and a distribution pattern was seen to have increasing macroalgal biomass from the upper to lower intertidal level. The sampling sites shared more than 50% similarity of their macroalgal species, indicating a relatively homogeneous distribution. The highest (18.1±4.3 gr drywt m-2) and lowest (8.27±2.1 gr drywt m-2) mean of total seaweed biomass were recorded in winter and summer, respectively.
Conclusion: The assemblage composition of macroalgae significantly differs between hot and cold seasons, and there was no substantial compositional variation of seaweeds communities along the tidal gradient. The macroalgal distribution was largely homogeneous with no significant difference among the research areas at sampling seasons.
