This study simulated outdoor environmental living conditions and observed the growth rates and changes of several photosynthetic pigments (Chl a, Car, PE, and PC) in Hypnea cervicornis J. Agardh (Gigartinales, Rhodophyta) by setting up different ranges of salinity (25, 30, 35, 40, 45, and 50) and temperature (15, 20, 25, and 30°C). At conditions of culture, the results are as follows. (1) Changes in salinity and temperature have significant effects on the growth of H. cervicornis. The growth rates first increase then decrease as the temperature increases, while growth tends to decline as salinity increases. The optimum salinity and temperature conditions for growth are 25 and 25°C, respectively. (2) Salinity and temperature have significant or extremely significant effects on photosynthetic pigments (Chl a, Car, PE, and PC) in H. cervicornis. The results of this study are advantageous to ensure propagation and economic development of this species in the southern sea area of China.

Green tides" are vast accumulations of unattached green macroalgae associated with eutrophicated marine environments. It had major ecological and economic impacts globally, thus understanding of their detailed conditions was required to inform management decisions. Chaetomorpha valida (Cladophoraceae, Chlorophyta), as a fouling green alga, was found in aquaculture ponds along the coast of Dalian and Rongcheng cities, People's Republic of China in the past few years. Seasonal abundances of this macroalga in China have presented a significant nuisance and caused great loss to the local aquaculture. Using unialgal cultures, the effect of temperature and irradiance on growth and reproduction were investigated. Healthy growth and reproduction occurred in the range of 17-29°C while the upper lethal limit was at 33°C. A suitable temperature range over 21-29°C and a relatively high irradiance of 108 μmol photons m −2 s −1 were more favorable for growth and reproduction. According to our observations, the diversity of reproductive approaches and wide adaption to temperature can be considered to be key factors that facilitate its excessive growth and colonization in spring and summer. Our results provide a basis for establishing a forecast system and taking remediation measures against seasonal green tides of this macroalga.

The marine green alga Chaetomorpha valida (Cladophoraceae, Cladophorales) has been found for several years fouling aquaculture ponds along coasts of the cities Dalian and Rongcheng, P.R. China. Using unialgal culture and microscopic observation, we completed the life history of C. valida and discovered fragment regeneration for the first time. The life history comprised an isomorphic alternation between gametophytes and sporophytes typical of most other members of the Cladophorales. Male and female gametes fused into zygotes then developed into sporophytes. Quadriflagellate zoospores produced by mature sprophytes gave rise to new gametophytes that yielded biflagellate gametes. Germination of zygotes and zoospores was of the bipolar erect type, as observed in some other species of Chaetomorpha. Fragment regeneration occurred in both gametophytes and sporophytes via production of polar algal fragments, which directly developed into entire filaments to give a self-replicating gene­ration. The results improved understanding of the seasonal abundances of C. valida in spring and summer.

Acrochaete leptochaete (Huber) Nielsen (Chaetophoraceae, Chlorophyta) was isolated from the macroalgae Chaetomorpha collected from intertidal pools in Rongcheng, Shandong, China. 18S rDNA combined with ITS regions were used to ascertain the morphological identifi cation of the isolated material. Based on the unialgal culture, asexual reproduction and growth characteristics of A . leptochaete were investigated over wide ranges of temperature and irradiance. Results revealed that asexual reproduction of A . leptochaete could be realized by bifl agellate zoospores. The zoospores germinated directly to give selfreplicating generations. Zoospore germination was bipolar. A temperature range from 13-21°C and a lower irradiance of 36 μmol/ (m 2 ·s) were most favorable for the growth of A . leptochaete . Thallus organization, an important taxonomic criterion for the genus Acrochaete , was affected markedly by temperature and irradiance. Our results extend the knowledge about the species' general biology and its morphological plasticity. For classifi cation and identifi cation of a simple microphytic algae like A . leptochaete , which are traditionally placed in the class Chaetophoraceae, we propose that molecular tools associated with culture observations are applied.

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