Sargassum

Seaweeds are often miscalled as seagrass due to their similar morphology. ťHowever, seaweeds are not plants, but they are primitive organisms possessing differentiated cell types. ťThey belong to marine algae for which they lack roots, vascular bundle tissues and do not produce flowers, fruits and seeds.ťInstead, it anchors to substratum by structure called holdfast without the ability to gather nutrients.ťGaseous exchange and absorption of nutrients take place across all of its tissues via diffusion.ťPhotosynthesis in most plants take place only in their leaves, however seaweed can carry out photosynthesis in all tissues.ťIt possesses numerous tiny air-filled vesicles which keep the whole alga buoyant and maintain up-right position in the water column.

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Over 200 species of marine macrobenthic algae have been reported in Hong Kong waters. ťAmong all macroalgae flourishing in the Hong Kong eastern waters in winter, brown seaweedof the genus Sargassum is the dominant type among the standing crop especially in areas exposing to strong or moderately strong waves.ťThey exhibit a strong seasonality in their abundance, during which they grow rapidly in winter months from October to May, and disappear (die-back) completely in summer from June to September.ťSexual reproduction takes place in Sargassum mainly in winter which involves the fusion of sperm and ovum.ťFertilized egg in its early stage of germination falls down on some solid substratum and develops into a typical thallus.ťAsexual reproduction can also take place in seaweeds through fragmentation or division.ťť

Name in Chinese: ´Ð¼õÜeÿü»

Status:Å¥Very Common in winter

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