Acrochaete leptochaete, a species in Chaetophoraceae （Chlorophyta）, was observed during our recent laboratory culture of the macroalgae Chaetornorpha that was originally collected from an intertidal pool in Rongcheng, Shandong Province, China. This is the first record of this species in China. Its morphology, taxonomy, and distribution were introduced and discussed in detail. Isolated culture experiments at different temperatures （9-29℃） and light intensities （36-108 μmol/m^2.s） were also carried out. The culture-based observations have extended our knowledge of growth morphology and general biology of the species.
Pyrenoids found in green algae Order Ulvales have taxonomical significance.Their morphology,microstructure,and the location and number in the cells have been widely used as identification criteria. As these traits can be affected by environmental conditions,it is necessary to look for other different characteristics.Here pyrenoids in several algae species collected along the Qingdao coast were studied for such purpose. The morphology and distribution of pyrenoids in the cells,as well as their change in different parts of the frond and at different times were studied with light microscope.The results are as follows.Pyrenoids appeared to be spherical or oval in observed Ulvales'algae cells.They were embedded in chloroplasts with the number of 1-3 per cell on average.The number of pyrenoids for Ulva pertusa could change drastically with continuing culture and could reach up to 10-20 per cell in late-growth stages.Generally, the pyrenoids in the marginal part were more observable than those in the central part for Ulva pertusa. In addition, the basal part of frond had more distinct pyrenoids with an average diameter of 2.42 μm for Enteromorpha linza. For some species the pyrenoids were difficult to be observed while dark treatment made them more distinguishable.The apoptosis rate of pyrenoids in different species varied under continuing dark treatment, which could be used to identify different species. Pyrenoids disappeared faster in E. linza than those in E.intestinalis.
Combining some information from field investigation of algae along the coastal areas in China and a few pictures materialized from the western Yellow Sea in 2008,authors analyze the necessary conditions and possible water area in China producing a large biomass,some reasons for firestorm,and the possibility of the reappearance of marine bloom green alga Enteromorpha prolifera.The change of habitats and the increase of nutritional levels related to the water area could be considered as direct reasons.It was transferred northward by the combination of the flow of rainwater,wind and alongshore marine current.The original region of large biomass produced is possibly located in the southwestern Yellow sea.It will possibly be appearing again in the coming years or in the future.A summary is also given referring to its reproduction,development and distribution worldwide.
