Effects of temperature and irradiance on early development of Chondrus ocellatus Holm (Gigartinaceae, Rhodophyta)

Chondrus is a type of commercially produced red seaweed that widely used for food and carrageen extraction. Although the natural life history of the alga had been well understood, the factors influencing development of the tetraspore and carpospore remain poorly understood. In the perspective of seedling resources, the regulation of early development is crucial for the seedling nursing; therefore, it is necessary to understand the physiological influences during its early development. In this study, we studied the effects of temperature and irradiance on the early development of Chondrus ocellatus Holm under laboratory conditions. The released tetraspores and carpospores were cultivated at different temperatures (10–28°C) and irradiances (10, 60 μmol photons m⁻²s⁻¹) with a photoperiod of 12L:12D. The results indicate that both tetraspores and carpospores are tolerant to temperatures of 10–25°C, and have the highest relative growth rate at 20°C. Irradiance variances influenced the growth of the discoid crusts, and the influence was more significant with increasing temperature; 60 μmol photons m⁻²s⁻¹ was more suitable than 10 μmol photons m⁻²s⁻¹. The optimum temperature and irradiance for the development of seedlings was 20°C and 60 μmol photons m⁻²s⁻¹, respectively.     

Cryopreservation of Gametophytes of Laminaria japonica （Phaeophyta） Using Encapsulation-Dehydration with Two-Step Cooling Method

Gametophytes of Laminaria japonica were cryopreserved in liquid nitrogen using encapsulation-dehydration with two-step cooling method. Gametophytes cultured at 10℃ and under continuous irradiance of 30 μmol m-2 s-1 for 3 weeks were encapsulated in calcium alginate beads. The beads were dehydrated in 0.4 molL-1 sucrose prepared with seawater for 6 h, desiccated in an incubator set at 10℃ and 70% relative humidity for 4 h, pre-frozen at either -40℃ or -60℃ for 30 min, and stored in liquid nitrogen for ＞24 h. As high as 43% of survival rate was observed when gametophytes were thawed by placing the beads in 40℃seawater and re-hydrated in 0.05 molL-1 citrate sodium prepared using 30‰ NaC1 7 d later. More cells of male gametophytes survived the whole procedure in comparison with female gametophytes. The cells of gametophytes surviving the preservation were able to grow asexually and produce morphologically normal sporophytes.     

Light demands of juvenileLaminaria japonica

The light demands of seaweeds is an interesting and rather complex phenomenon because they depend not only on the species but also on their different development stages. Even different parts of the same plant sometimes have different light demands. Light control is an important procedure at large scaleLaminaria nursery stations in China. Technicians and scientists have different viewpoints on the best method to regulate light. A culture study onLaminaria japonica starting from zoospores to several centimeter sporophytes to find the optimal and critical irradiance ranges for juvenileLaminaria at different development stages added more knowledge on this aspect. Experiment results show gametophytes can not tolerate irradiance of more than 150 μE m⁻²s⁻¹ while sporophytes can tolerate more than 519 μE m⁻²s⁻¹. This big difference starts from the very early stage of 1-to 2-celled sporophytes. The biological basis and mechanism of this phenomenon need further research. Contribution No. 1515 from the Institute of Oceanology, Academia Sinica Contribution No. 1 from the Experimental Marine Biological Laboratory     

Study on gametophyte vegetative growth ofUndaria pinnatifida and its applications

When cultured under certain environmental conditions (25°C, light intensity 80 μmol/m²·s, LD 12/12, in enriched seawater medium with 7×10⁻⁴ mol/L NO₃−N, 1.56×10⁻⁴ mol/L, PO₄−P and supplements of other elements like Mn, Fe, I, etc.), male and female gametophytes ofU. pinnatifida kept growing vegetatively and propagated fast at average daily fresh weight increase rate of about 20%. The empirical formulaG _m=G _o·3^m was established to estimate the output of vegetative gametophytes. Vigorous vegetative gametophyte cells began to form reproductive structures (oogonium and spermatangium, when the temperature was lower than 25°C and other environmental factors were kept optimal. The sufficient supply of gametophyte cells provided enough seeds for raisingUndaria sporelings on production scale. Controlled cross-breeding experiments using selected male and female gametophyte clones which increase their cell number by mitosis instead of meiosis were also carried out in vitro. Juvenile sporophytes from the cross-breeding had almost the same length and width increase rates as those of the control. The fact that vegetative gametophytes can be purposely selected, propagated quickly, cross-bred, with the resulting sporophytes having almost the same characteristics leads to a new way to select desiredUndaria strains for long time use without losing the desired economic characteristics. Contribution No. 2696 from the Institute of Oceanology, Chinese Academy of Sciences. Supported by National Natural Science Foundation of China.     

Optimization of conditions for tetraspore release and assessment of photosynthetic activities for different generation branches of Gracilaria lemaneiformis Bory

Gracilaria lemaneiformis Bory is an economically important alga that is primarily used for agar production. Although tetraspores are ideal seeds for the cultivation of G. lemaneiformis, the most popular culture method is currently based on vegetative fragments, which is labor-intensive and time-consuming. In this study, we optimized the conditions for tetraspore release and evaluated the photosynthetic activities of different colonies formed from the branches of G. lemaneiformis using a PAM (pulse-amplitude-modulated) measuring system. The results showed that variations in temperature and salinityhad significant effects on tetraspore yield. However, variations in the photon flux density (from 15 μmol m⁻² s⁻¹ to 480 μmol m⁻² s⁻¹) had no apparent effect on tetraspore yield. Moreover, the PAM-parameters Y(I), Y(II), ETR(I), ETR(II) and F _v/F _m of colonies formed from different branches showed the same trend: parameter values of first generation branches>second generation branches>third generation branches. These results suggest that the photosynthetic activities of different colonies of branches changed with the same trend. Furthermore, photosynthesis in G. lemaneiformis was found to be involved in vegetative reproduction and tetraspore formation. Finally, the first generation branches grew slowly, but accumulated organic compounds to form large numbers of tetraspores. Taken together, these results showed that the first generation branches are ideal materials for the release of tetraspores.     

Formation and early development of tetraspores of Polysiphonia urceolata （Rhodomelaceae, Rhodophyta）

Polysiphonia urceolata is one type of potential commercial red seaweeds used for breeding and cultivation, because of its significant biochemical and biomedical application. However, the information of breeding and seedling incubation for cultivation is limited, especially the early development. In this study, tetrasporohyte and gametophyte of P. urceolata were taken as the study materials in Huiquan Bay, Qingdao, China. The cleaned and sterilized tetrasporophytes and gametophytes were pre-cultured in sterilized seawater, then nurtured at 18°C, 25 μmol photons m⁻² s⁻¹ in 12:12 h (light:dark) photoperiod. Continuous observation under microscope showed that the early development consists of bipolar division stage and seedling stage. In the division stage, tetraspores germinate into bipolar sporelings that further differentiate into a colorless rhizoidal portion and a lightly pigmented upright shoot. The lightly pigmented rhizoidal cell develops to a rhizoid and the larger pigmented cell transforms to an erect axis. In the seedling stage, several quasi-protuberances appear on the erect axis and form juvenile seedlings. The results demonstrate the culture of P. urceolata from tetraspores under laboratory conditions. Supported by National Key Technology Support Program, Development Program of China (No.2006AA09Z21), National Natural Science Foundation of China (No. 40618001 and N_CUHK438/06) and Shandong Agricultural Seed Stock Breeding Project     

Effect of temperature and irradiance on the growth and reproduction of Enteromorpha prolifera J. Ag. （Chlorophycophyta,Chlorophyceae）

Effect of temperature and irradiance on growth and reproduction of Enteromorpha prolifera that bloomed offshore along the Qingdao coast in summer 2008, was studied. It was showed that E. prolifera propagated mainly asexually with specific growth rate （SGR） of 10.47 at 25℃/40 μmol m^-2s^-1. Under this condition, gametes with two flagellate formed and released in 5 days. At the beginning of the development, the unicell gamete divided into two cells with heteropolarity, and then the apical cell developed into thalli primordial cells, whereas the basal cell developed into rhizoid primordial cells. In 8-day culture, the monoplast gamete developed into juvenile germling of 240 μm in length. Unreleased gametes can develop directly within the alga body. E. prolifera could either reproduce through lateral branching or fragmenting except apomixis revealed by Microscopic observation. On aged tissue of E. prolifera, although the degraded pigments partially remained in faded algal filaments, numerous vegetative cells could still divide actively in the algal tissues.     

Impact of microzooplankton and Calanus sinicus (Brodsky, 1962) on phytoplankton in the Yellow Sea during early summer

Dilution incubations and Calanus sinicus addition incubations were simultaneously conducted at five stations in the Yellow Sea in June of 2004 to evaluate the impact of microzooplankton and Calanus sinicus on phytoplankton based on the Chlorophyll a (Chl-a) levels. The Chl-a growth rates (k) ranged from 0.60–1.67 d⁻¹, while microzooplankton grazed the Chl-a at rates (g) of 0.29–0.62 d^t-1. The addition of C. sinicus enhanced the Chl-a growth rate (Z) by 0.004–0.037 d⁻¹ ind.⁻¹ L. C. sinicus abundance ranged from 84.1–160.9 ind. m⁻³, which occupied 90.7%–99.1% of the copepod (>500 μm) population. The in-situ increase in phytoplankton by C. sinicus community was estimated to be 0.000 4–0.005 9 d⁻¹. These results showed that microzooplankton were the main grazers of phytoplankton, while C. sinicus induced a slight increase in the levels of phytoplankton.     

Distributions of inorganic nutrients in the bohai sea of china

1　Introduction　TheBohaiSeaislocatedinthenorthernChinawithlongitudesofbetween 117°38′Eand 12 2°31′Eandlat itudesofbetween 37°0 8′Nand 4 1°0 2′N .Itisashal lowseawithanaveragewaterdepthof 18m (LiuandZhang ,2 0 0 0 ) .Severalbigrivers ,suchastheLiaoheRiver,theHaiheRiverandtheYellowRiver ,findtheirwaysintotheBohaiSeaandtransportlargeamountofnutrientsandsuspendedmattersfromthecontinentintothesea (Zhangetal.,1994 ;Zhang ,1996 ) .Duringthelasttwodecades ,marineenviron mentintheBohai…     

Effects of temperature, salinity, light intensity, and pH on the eicosapentaenoic acid production of Pinguiococcus pyrenoidosus

The effects of temperature, light intensity, salinity, and initial pH on the growth and fatty acid composition of Pinguiococcus pyrenoidosus 2078 were studied for eicosapentaenoic acid (EPA) production potential. The fatty acid composition was assayed by gas chromatography-mass spectrometry, which indicated that the main fatty acids were C14:0, C16:0 and EPA. The highest EPA percentage 20.83% of total fatty acids was obtained at 20℃ with the temperature being set at 20, 24, and 28℃. Under different salinities and light intensities, the highest percentages of total polyunsaturated fatty acids (PUFAs) and EPA were 17.82% and 31.37% of total fatty acids, respectively, which were achieved at salinity 30 and 100μmol photon m-2s-1 illumination. The highest percentages of total PUFAs and EPA were 38.75% and 23.13% of total fatty acids, respectively, which were reached at an initial pH of 6 with the test range being from 5.0 to 9.0.     

Methodology for studies of carbon dynamics between phytoplankton primary production and heterotrophic bacterial secondary production

The SCENTO-System was used to study the carbon dynamics between phytoplankton primary production and heterotrophic bacterial secondary production. Most of the methods used nowadays in situ for limnological synecology studies were applied. Primary production measurement showed an increasing tendency with increasing content of chlorophylla. It provided a true photosynthetic rate lying within the range of eutrophic lakes. Net EOC released from the algae ranged from 8.5 to 27.5 μg C l⁻¹(6h)⁻¹. Accompanying the algal products the number of bacteria increased from 1.475 ×10⁹ to 8.074×10⁹ cells l⁻¹. The bacterial mean cell volume was small, between 0.0315 and 0.0548μm³. Bacterial carbon production from direct growth estimates was compared with independent calculations of bacterial growth from EOC uptake and³H-thymidine incorporation. Direct estimates were 2.97–10.0 μg Cl⁻¹ (24h)⁻¹ with the exception of a zero-growth on the third day. EOC uptake was 123.5–191.0 μg Cl⁻¹ (6h)⁻¹. That calculated from³H-thymidine incorporation was 0.2–0.5 μg Cl⁻¹ (6h)⁻¹.¹⁴C-glucose dark uptake ran parallel to the increasing bacterial biomass. The respiration of glucose was 6.5% (avg.) of the gross uptake. Since the system operated without grazing pressure, a real carbon flow from primary production to bacterial secondary production could be observed.     

Molecular identification and culture observation on <Emphasis Type="Italic">Acrochaete leptochaete</Emphasis> (Chaetophoraceae,Chlorophyta) from China

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 identification 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 biflagellate zoospores. The zoospores germinated directly to give self- replicating generations. Zoospore germination was bipolar. A temperature range from 13-21°C and a lower irradiance of 36 μmol/(m2·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 classification and identification 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.     

Annual production ofBranchiura sowerbyi (Oligochaeta: Tubificidae) in the Donghu Lake,Wuhan, China

Branchiura sowerbyi in the Donghu Lake (Wuhan, China) completes its life cycle in one year. Its production rates were 6.7 g m⁻² yr⁻¹ (wet weight) during the period from April 1962 to May 1963 and 8.6g m⁻² yr⁻¹ during the period from August 1963 to August 1964. The standing stocks in corresponding periods were 1.9g m⁻² (wet weight) and 1.1g m⁻², and theP/B ratios were 3.6 and 7.8. Based on the standing stock during 1973–1975, an evaluation of recent productin levels ofB. sowerbyi in Donghu Lake has also been made (i.e. 5.7–33.5g m⁻² yr⁻¹).     

The South Pacific Subtropical Mode Water in the Tasman Sea

From the synopical CTD sections in the WOCE PR11 repeated cruises, the South Pacific Subtropical Mode Water (SPSTMW) has been identified in the region of the Tasman Front Extension (TFE) around 29?S to the east of Australia. In the depth range of 150-250 m, the SPSTMW appears as a thermostad with vertical temperature gradient lower than 1.6℃(100 m)-1 and a tem- perature range of 16.5-19.5℃ and as a pycnostad with PV lower than 2×10-10 m-1 s-1 and a potential density range of 25.4-26.0 kg m-3. Like the subtropical mode waters in the North Atlantic and North Pacific, the formation of the SPSTMW is associated with the convective mixing during the austral wintertime as manifested from the time series of the Argo floats. And cold water entrains into the mixed layer with the deepening mixed layer from September to the middle of October. During the wintertime formation process, mesoscale eddies prevailing in the TFE region play an important role in the SPSTMW formation, and have a great effect on the SPSTMW distribution in the next year. The deeper (shallower) mixed layer in wintertime, consistent with the depressed (uplifted) permanent thermocline, is formed by the anticyclonic (cyclonic) eddies, and the substantial mode water thicker than 50 m is mainly found in the region of the anticyclonic eddies where the permanent thermocline is deeper than 450 m.     

Effects of blue light on gametophyte development of Laminaria japonica (Laminariales, Phaeophyta)

Laminaria gametophyte was greatly influenced by light in its growth and development. Using light-emitting diodes (LED) as blue and red light sources, we analyzed the light effect on gametophytes development ofLaminaria japonica Aresch. The gametophytes were obtained from zoospores collected in April, May, July, 2003 and September, 2004. We found that the growth of gametophytes was stimulated by increasing intensity of blue light (BL) and red light (RL) illumination, of which BL was obviously stronger than that of RL. The fertilization of gametophytes depended largely on BL, and only sufficient BL illumination could take the reproductive effect. In addition, we noticed that there was a significant difference in light responses for gametophytes developed from zoospore collected in different times. For zoospores released in April, under BL₁ (73.90 μmol photons/m·s), the unicellular female gametophytes and multi-cellular male gametophytes produced eggs and sperms respectively, and further developed towards sporophytes. However, for gametophytes developed in May, July or September, they became multi-cellular and never formed oogonia or antheridia. It is believed that theLaminaria sporangium maturation stage could affect the gametophytes reaction to BL under laboratory culture conditions. Therefore, cryptochrome- or phototropin-like BL photoreceptors is probably involved in BL-induced development ofLaminaria gametophytes. This research was supported by the NSFC (No.40376049) and Japan Society for the Promotion of Science (The Invitation Fellowship for Research in Japan 2002).     

Effects of salinity, light and temperature on growth rates of two species of Gracilaria （Rhodophyta）

Effects of temperature, salinity and light intensity on growth rates of Gracilaria lichenoides and G. tenuistipitata var. liui Zhang et Xia were tested. Eight to ten levels of each factor were first tested separately. The best growth rate was obtained under the conditions of 32°C, 30 and 240 μmol/(m²·s) for G. lichenoides, and 24°C, 20 and 200 μmol/(m²·s) for G. tenuistipitata, respectively. Then a uniform design was used to evaluate the optimal combinations of the three factors. The best conditions for the highest daily specific growth rates (% increase in wet weight) are determined to be 31.30°C, 32.10, and 287.23 μmol/(m²·s) for G. lichenoides (16.26%/d), and 25.38°C, 21.10, and 229.07 μmol/(m²·s) for G. tenuistipitata (14.83%/d), respectively. Supported by the 908 Special Program (908-02-04-07), the National Basic Research Program of China (973 Program, No. 2006CB400608), and K. C. Wong Magna Fund in Ningbo University     

DYNAMIC CHANGES OF INORGANIC NITROGEN AND ASTAXANTI—IIN ACCUMULATION IN HAEMATOCOCCUS PLUVIALIS

This study on dynamic changes of culture color,astaxanthin and chlorophylls,inorganic N including N-NO3^-,N-NO2^- and N-NH4^ in batch culture of Haematococcus pluvialis exposed to different additive nitrate concentration showed(1)ast/chl ratio was over 0.8 for brown and red algae,but was usually less than 0.5 for green and yellow algae;(2)N-NO3^-,in general,was unstable and decreased,except for a small unexpected increase in nitrate enriched treatment groups;(3)measurable amounts of N-NO2^- and N-NH4^ were observed respectively with three change modes although no extemal nitrite and ammonia were added into the culture;(4)a non-linear correlation between ast/chl ratio(or color)changes and the levels of N-NO3^-,N-NO2^-,N-NH4^ in H.pluvialis culture;(5)up and down variation of the ast/chl ratio occurred simultaneously with a perceptible color change from yellow to brown(or red)when N-NO3^-,N-NO2^- and N-NH4^ fluctuated around 30,5,5μmol/L respectively;(6)existence of three dynamic modes of N-NO3^-,N-NO2^- and N-NH4^ changes,obviously associated with initial extemal nitrate;(7)the key level of total inorganic N concentration regulating the above physiological changes during indoor cultivation was about 50 μmol/L;and(8)0.5-10mmol/L of nitrate was theoretically conducive to cell growth in batch culture.     

Induction and cultivation of cloned filaments of Polysiphonia urceolata (Rhodomelaceae, Rhodophyta)

A filamentous clone of Polysiphonia urceolata was regenerated from segments cut from the fronds of gametophytes. Unlike wild thalli with short virgate branchlets, the clone was filamentous with few branches. Many transparent trichoblasts arose from pericentral cells during the induction culture, but these were seldom observed during normal growth. The trichoblasts were uniseriate, often colorless, and formed lobed rhizoids rapidly when they came into contact with solid substrates. In addition to morphological characteristics, the photosynthetic properties and growth conditions of the clone differed from those of the mother plant. Cross-gradient light and temperature culture experiments revealed that the most favorable conditions for culture of the filamentous clone were 22°C and 95-120 μE/(m2-s) light intensity. The photosynthetic light saturation value for filaments was approx. 100 μE/(m2-s), which is far lower than that of wild thalli. These results could be used to develop techniques for mass cultures of P. urceolata in photobioreactors for production of seed stock or bioactive products.     

Size-fractionated phytoplankton biomass in autumn of the Changjiang （Yangtze） River Estuary and its adjacent waters after the Three Gorges Dam construction

A cruise was undertaken from 3rd to 8th November 2004 in Changjiang （Yangtze） River Estuary and its adjacent waters to investigate the spatial biomass distribution and size composition of phytoplankton. Chlorophyll-a （Chl-a） concentration ranged 0.42-1.17 μg L^-1 and 0.41-10.43 μg L^-1 inside and outside the river mouth, with the mean value 0.73 μg L^-1 and 1.86 μg L^-1, respectively. Compared with the Chl-a concentration in summer of 2004, the mean value was much lower inside, and a little higher outside the river mouth. The maximal Chl-a was 10.43 μg L^-1 at station 18 （122.67°E, 31.25°N）, and the region of high Chl-a concentration was observed in the central survey area between 122.5°E and 123.0°E. In the stations located east of 122.5°E, Chl-a concentration was generally high in the upper layers above 5 m due to water stratification. In the survey area, the average Chl-a in sizes of 〉20 μm and 〈20 μm was 0.28 μg L^-1 and 1.40 μg L^-1, respectively. High Chl-a concentration of 〈20 μm size-fraction indicated that the nanophytoplankton and picophytoplankton contributed the most to the biomass of phytoplankton. Skeletonema costatum, Prorocentrum micans and Scrippsiella trochoidea were the dominant species in surface water. The spatial distribution of cell abundance of phytoplankton was patchy and did not agree well with that of Chl-a, as the cell abundance could not distinguish the differences in shape and size of phytoplankton cells. Nitrate and silicate behaved conservatively, but the former could probably be the limitation factor to algal biomass at offshore stations. The distribution of phosphate scattered considerably, and its relation to the phytoplankton biomass was complicated.     

Effects of NO and Different Media on the Growth of Prorocentrum micans

1Introduction NOisadiffusible,gaseousfreeradicalthatplaysimportantrolesinanimalsandplants.Itfunctionsin diseaseresistance,abioticstress,celldeath,respira tion,senescence,rootdevelopments,germinationandhormoneresponses.Itisanunusualsignalinthatitis areactive,lipophilicandvolatilefreeradicalthatcanbecytotoxic.ThewidespreadbiologicalsignificanceofnitricoxidewasrecognizedbySciencein1992whichnamedthefreeradicalNO‘Moleculeoftheyear’,andin1998theNobelPrizeinPhysiologyandMedicinewasawardedforwor…