A study was made on the dial rhythm and variation of Chl a and photosynthesis in the nearshore of qingdao. Both Chl a and photosynthesis show obvious dial rhythm; the peak value of surface Chl a appeared in the afternoon,while bottom Chl a around noon;the maximum value of photosynthetic rate appeared in the morning, noon and afternoon. The scope of the diet rhythm of Chl a and photosynthesis and the time for the appearance of the peak value varied in different months. Moreover, the mechanism of the formation of this diet rhythm is also discussed in this paper.

海水盐度在很大程度上受到潮汐、蒸发作用以及降水等的影响.本实验研究了在短时(数分钟)或长时(数天)的不同盐度处理条件下,裂片石莼(Ulva fasciata Delile)幼体的生长及光合作用响应,并评估海水盐度变化对裂片石莼生活史早期阶段的影响.结果表明,经短时间(数分钟)的低盐(25和15)或高盐海水(45)处理后,裂片石莼幼体的最大净光合作用速率(NPRm)均显著下降.但30 min后,在盐度25海水条件下,裂片石莼幼体仍保持较高的光合作用活性(70%以上).经过8 d的长时间培养,在盐度从34降低至15时,裂片石莼幼体的光合作用及相对生长速率(RGR)均显著降低,但藻体中的丙二醛(MDA)含量却逐渐增加.当盐度从34下降至25时,裂片石莼幼体的RGR的差异性不显著,但却显著地影响了幼体的形态特征.高盐条件(45)显著地降低了裂片石莼幼体的RGR及光合作用活性,却增加了藻体的MDA含量.海水盐度增加对裂片石莼幼体具有比海水淡化更大的毒害作用.无论短时或长时间培养,生长于25至34海水盐度范围内的裂片石莼幼体均表现出较好的光合适应性.裂片石莼幼体对盐度(25至34)的广泛耐受性在一定程度上与其对周期性潮汐变化的长期适应有关.

Intertidal marine macroalgae experience periodical exposures during low tide due to their zonational distribution. The duration of such emersion leads to different exposures of the plants to light and aerial CO₂, which then affect the physiology of them to different extents.The ecophysiological responses to light and CO₂ were investigated during emersion in two red algae Gloiopeltis furcata and Gigartina intermedia, and two brown algae Petaloniafascia and Sargassum hemiphyllum, growing along the Shantou coast of China. The light-saturated net photosynthesis in G. furcata and P. fascia showed an increase followed by slightly desiccation, whereas that in G.intermedia and S. hemiphyllum exhibited a continuous decrease with water loss. In addition, the upper-zonated G. furcata and P. fascia,exhibited higher photosynthetic tolerance to desiccation and required higher light level to saturate their photosynthesis than the lower-zonated G. intermedia and S. hemiphyllum. Desiccation had less effect on dark respiration in these four algae compared with photosynthesis. The light-saturated net photosynthesis increased with increased CO₂ concentrations, being saturated at CO₂ concentrations higher than the present atmospheric level in G. furcata, G. intermedia and S. hemiphyllum during emersion. It was evident that the relative enhancement of photosynthesis by elevated CO₂ in those three algae increased, though the absolute values of photosynthetic enhancement owing to CO₂ increase were reduced when the desiccation statuses became more severe. However, in the case of desiccated P. fascia (water loss being greater than 20%), light saturated net photosynthesis was saturated with current ambient atmospheric CO₂ level. It is proposed that increasing atmospheric CO₂ will enhance the daily photosynthetic production in intertidal macroalgae by varied extents that were related to the species and zonation.

2007年以来，黄海连年爆发大规模浒苔绿潮，南黄海沿岸养殖筏架上的附生绿藻被认为是漂浮绿藻的主要来源之一。本研究对脱离筏架的浒苔样品进行室内培养实验，研究不同温度、盐度和光照条件下，其生长率和光合作用的变化，从而探讨浒苔脱离原附着基后适应不同环境的生理机制。结果显示，浒苔在14–27°C和26–32盐度范围内生长率和光合作用效率明显较高，最适温度和盐度为23°C和32，低温（<14°C）、高温（40°C）以及低盐（8）环境都不利于浒苔光合作用。与其他石莼属绿藻相比，浒苔对强光照具有较高的耐受性，其藻体复杂的分支结构，可能起一定的保护作用。温度对浒苔生长率的影响明显高于盐度的影响。总体而言，浒苔在5–32°C的温度范围和14–32的盐度范围内都能保持生长，而每年春季黄海南部的环境条件比较适宜脱落浒苔的快速生长。浒苔的内在生理特征与黄海南部适宜的环境条件相耦合，成为黄海浒苔绿潮爆发的原因之一。

In the present paper, the unicellular green alga Platymonas subcordiformis was entrapped in 2% (W/V) alginate, treated with CaCl₂ at different concentrations (0.5, 0.75, 1.0, 1.5 and 2.0 mol/dm³), cultured at 15℃ and 25℃.The growth rate and morphology were studied and photosynthesis and respiration rates were measured.The optimum conditions of immobilized culture is in 0.5 mol/dm³ of CaCl₂, at 25℃.Photosynthesis rate of immobilized cells is higher than free cultivated cells, and that at 15℃ than at 25℃.Under scanning electropic microscope, it was shown that the immobilized cells had larger size and rougher surface.The relationship between growth of immobilized cells and abiotic factors and the prospects of applying immobilized cultivation are also discussed.

An increase in the level of atmospheric carbon dioxide (CO₂) and the resultant rise in CO₂ in seawater alter the inorganic carbon concentrations of seawater. This change, known as ocean acidification, causes lower pH in seawater and may affect the physiology of seaweed species. Accordingly, the main goal of the current study was to determine the physiological responses of Bryopsis plumosa to elevated-CO₂. The results indicated that photosynthesis of B. plumosa was insignificantly affected to elevated-CO₂, but photosynthetic pigment contents and phenolics were significantly decreased. The results obtained from the research reveal that B. plumosa may become physiologically advanced when exposed to CO₂-induced ocean acidification. In particular, B. plumosa may be more able to compete with calcifying algae when it will become future predicted CO₂ scenario.

Cadmium (Cd) is a common heavy metal pollutant in the aquatic environment, generally toxic to plant growth and leading to growth inhibition and biomass reduction. To study the oxidation resistance in Sargassum fusiforme seedlings in response to inorganic Cd stress, we cultured the seedlings under two different Cd levels: natural seawater and high Cd stress. High Cd stress significantly inhibited the seedlings growth, and darkened the thalli color. Additionally, the pigment contents, growth rate, peroxidase (POD) activity, dehydroascorbic acid (DHA) content, and glutathione reductase (GR) activity in S. fusiforme were significantly reduced by high Cd treatment. Contrarily, the Cd accumulation, Cd²⁺ absorption rate, dark respiration/net photosynthetic rate (R_d/P_n), ascorbic acid (Vc) content, soluble protein (SP) content, glutathione (GSH), and the activities of superoxide dismutase (SOD) and catalase (CAT) of S. fusiforme under Cd treatment significantly increased compared to the control group. The decrease of malondialdehyde (MDA) was not significant. Although S. fusiforme seedlings increased the antioxidant activities of POD, SOD, Vc, and the AsA-GSH cycle to disseminate H₂O₂ and maintain healthy metabolism, high Cd stress caused Cd accumulation in the stem and leaves of S. fusiforme seedlings. The excessive Cd significantly restricted photosynthesis and reduced photosynthetic pigments in the seedlings, resulting in growth inhibition and deep morphological color, especially of the stems. High levels of Cd in seawater had toxic effects on commercial S. fusiforme seedlings, and risked this edible seaweed for human food.

The effect of temperature and salinity on the photosynthetic and respiratory rates of some seaweeds are reported.The regression equations for the seaweeds and their correlograms are discussed and compared.
The results indicate that the photosynthetic rate of E.binghamiae fronds shows a significant negative linear correlation (p<0.01) with changing of temperature (20-35℃),the optimum temperature being 20℃,while for the others there is a conic correlation between photosynthetic rate and temperature.The optimum temperature for photosynthesis is 23-25℃ for two species of Porphyra fronds,25-28℃ for Gracilaria sp.thalli and 23-30℃ for V.conglobata and S.hemiphyllum fronds,separately.The rates of respiration for all the studied species increase linearly with increasing temperature from 18 to 35℃.The optimum salinities for photosynthesis range from 26 to 32 for two species of Gracilaria,whose respiratory rates decrease gradually with increasing salinity.

The effects of seawater temperature on the physiological performance of three Halimeda species were studied for a period of 28 d. Five treatments were established for Halimeda cylindracea, Halimeda opuntia and Halimeda lacunalis, in triplicate aquaria representing a factorial temperature with 24°C, 28°C, 32°C, 34°C and 36°C, respectively. The average F_v/F_m of these species ranged from 0.732 to 0.756 between 24°C and 32°C but declined sharply between 34°C (0.457±0.035) and 36°C (0.122±0.014). Calcification was highest at 28°C, with net calcification rates (G_net) of (20.082±2.482) mg/(g·d), (12.825±1.623) mg/(g·d) and (6.411±1.029) mg/(g·d) for H. cylindracea, H. opuntia and H. lacunalis, respectively. Between 24°C and 32°C, the specific growth rate (SGR) of H. lacunalis (0.079%–0.110% d^–1) was lower than that of H. cylindracea (0.652%–1.644% d^–1) and H. opuntia (0.360%–1.527% d^–1). Three Halimeda species gradually bleached at 36°C during the study period. Malondialdehyde (MDA) and proline levels in tissues of the three Halimeda were higher in 34–36°C than those in 24–32°C. The results indicate that seawater temperature with range of 24–32°C could benefit the growth and calcification of these Halimeda species, however, extreme temperatures above 34°C have negative impacts. The measured physiological parameters also revealed that H. cylindracea and H. opuntia displayed broader temperature tolerance than H. lacunalis.