Tank cultivation of the red alga Palmaria palmata: Effects of intermittent light on growth rate, yield and growth kinetics

Tank cultivation of marine macroalgae involves air-agitation of the algal biomass and intermittent light conditions, i.e. periodic, short light exposure of the thalli in the range of 10 s at the water surface followed by plunging to low light or darkness at the tank bottom and recirculation back to the surface in the range of 1-2 min. Open questions relate to effects of surface irradiance on growth rate and yield in such tumble cultures and the possibility of chronic photoinhibition in full sunlight. A specially constructed shallow-depth tank combined with a dark tank allowed fast circulation times of approximately 5 s, at a density of 4.2 kg fresh weight (FW) m(-2) s(-1). Growth rate and yield of the red alga Palmaria palmata increased over a wide range of irradiances, with no signs of chronic photoinhibition, up to a growth-saturating irradiance of approximately 1600 mumol m(-2) s(-1) in yellowish light supplied by a sodium high pressure lamp at 16 h light per day. Maximum growth rate ranged at 12% FW d(-1), and maximum yield at 609 g FW m(-2) d(-1). This shows that high growth rates of individual thalli may be reached in a dense tumble culture, if high surface irradiances and short circulation times are supplied. Another aspect of intermittent light relates to possible changes of basic growth kinetics, as compared to continuous light. For this purpose on-line measurements of growth rate were performed with a daily light reduction by 50% in light-dark cycles of 1, 2 or 3 min duration during the daily light period. Growth rates at 10degreesC and 50 mumol photon m(-2) s- 1 dropped in all three intermittent light regimes during both the main light and dark periods and reached with all three periodicities approximately 50% of the control, with no apparent changes in basic growth kinetics, as compared to continuous light.

A genetic linkage map of Pacific white shrimp (Litopenaeus vannamei): sex-linked microsatellite markers and high recombination rates

Pacific white shrimp (Litopenaeus vannamei) is the leading species farmed in the Western Hemisphere and an economically important aquaculture species in China. In this project, a genetic linkage map was constructed using amplified fragment length polymorphism (AFLP) and microsatellite markers. One hundred and eight select AFLP primer combinations and 30 polymorphic microsatellite markers produced 2071 markers that were polymorphic in either of the parents and segregated in the progeny. Of these segregating markers, 319 were mapped to 45 linkage groups of the female framework map, covering a total of 4134.4 cM; and 267 markers were assigned to 45 linkage groups of the male map, covering a total of 3220.9 cM. High recombination rates were found in both parental maps. A sex-linked microsatellite marker was mapped on the female map with 6.6 cM to sex and a LOD of 17.8, two other microsatellite markers were also linked with both 8.6 cM to sex and LOD score of 14.3 and 16.4. The genetic maps presented here will serve as a basis for the construction of a high-resolution genetic map, quantitative trait loci (QTLs) detection, marker-assisted selection (MAS) and comparative genome mapping.

The recombination and expression of the allophycocyanin beta subunit gene in the chloroplast of Chlamydomonas reinhardtii

A Chlamydomonas reinhardtii (C. reinhardtii) chloroplast expression vector, papc-B, containing the apc-B gene that encodes the beta subunit of the light-harvesting antenna protein allophycocyanin (APC) of cyanobacteria, was constructed and transferred to the chloroplast genome of C. reinhardtii by the biolistic method. The transformants were identified by Southern blot, Western blot and ELISA assays after selection on resistant medium. The recombinant APC beta subunit was expressed in the C. reinhardtii chloroplast and accounted for up to 2-3% (w/w) of the total soluble protein (TSP), suggesting a promising prospect of using C. reinhardtii chloroplasts to produce functional plant-derived proteins.

Modification to the Hardisty equation, regarding the relationship between sediment transport rate and particle size

Bagnold-type bed-load equations are widely used for the determination of sediment transport rate in marine environments. The accuracy of these equations depends upon the definition of the coefficient k(1) in the equations, which is a function of particle size. Hardisty (1983) has attempted to establish the relationship between k(1) and particle size, but there is an error in his analytical result. Our reanalysis of the original flume data results in new formulae for the coefficient. Furthermore, we found that the k(1) values should be derived using u(1) and u(1cr) data; the use of the vertical mean velocity in flumes to replace u(1) will lead to considerably higher k(1) values and overestimation of sediment transport rates.

Paleoenvironmental change in the middle Okinawa Trough since the last deglaciation: Evidence from the sedimentation rate and planktonic foraminiferal record

Well-dated, high-resolution records of planktonic foraminifera and oxygen isotopes from two sediment cores, A7 and E017, in the middle Okinawa Trough reveal strong and rapid millennial-scale climate changes since similar to 18 to 17 thousand years before present (kyr B.P.). Sedimentation rate shows a sudden drop at similar to 11.2 cal. kyr B.P. due to a rapid rise of sea level after the Younger Dryas (YD) and consequently submergence of the large continental shelf on the East China Sea (ECS) and the retreat of the estuary providing sediment to the basin. During the last deglaciation, the relative abundance of warm and cold species of planktonic foraminifera fluctuates strongly, consistent with the timing of sea surface temperature (SST) variations determined from Mg/Ca measurements of planktonic foraminifera from one of the two cores. These fluctuations are coeval with climate variation recorded in the Greenland ice cores and North Atlantic sediments, namely Heinrich event 1 (H1), Bolling-Allerod (B/A) and YD events. At about 9.4 kyr B.P., a sudden change in the relative abundance of shallow to deep planktonic species probably indicates a sudden strengthening of the Kuroshio Current in the Okinawa Trough, which was synchronous with a rapid sea-level rise at 9.5-9.2 kyr B.P. in the ECS, Yellow Sea (YS) and South China Sea (SCS). The abundance of planktonic foraminiferal species, together with Mg/Ca based SST, exhibits millennial-scale oscillations during the Holocene, with 7 cold events (at about 1.7, 2.3-4.6, 6.2, 7.3, 8.2, 9.6, 10.6 cal. kyr BP) superimposed on a Holocene warming trend. This Holocene trend, together with centennial-scale SST variations superimposed on the last deglacial trend, suggests that both high and low latitude influences affected the climatology of the Okinawa Trough. (c) 2006 Elsevier B.V. All rights reserved.

Analysis on suspended sediment deposition rate for muddy coast of reclaimed land

A new expression for calculating suspended fine-sediment deposition rate is developed based on theoretic analysis and experiments. The resulting equation is applied to simulation of fine sediment deposition in the reclaimed land in the Hangzhou Bay, China. The hydrodynamic environment in this area is solved by use of a long wave model, which gives the 2D-velocity field and considers bathymetric changes due to fine sediment deposition. The expression is proved convenient to use in engineering practice, and the predicted deposition rate agrees with the annual data available from field measurements from the first year to the third year after the construction of the long groin as a reclaiming method.

Studies on growth rate and grazing mortality rate by microzooplankton of size-fractionated phytoplankton in spring and summer in the Jiaozhou Bay, China

Dilution experiments were performed to examine the growth rate and grazing mortality rate of size-fractionated phytoplankton at three typical stations, inside and outside the bay, in the spring and summer of 2003 in the Jiaozhou Bay, China. in spring, the phytoplankton community structure was similar among the three stations, and was mainly composed of nanophytoplankton, such as, Skeletonema costatum and Cylindrotheca closterium. The structure became significantly different for the three stations in summer, when the dominant species at Stas A, B and C were Chaetoceros curvisetus, Pseudo-nitzschia delicatissima, C. affinis, C. debilis, Coscinodiscus oculus-iridis and Paralia sulcata respectively. Tintinnopsis beroidea and T. tsingtaoensis were the dominant species in spring, whereas the microzooplankton was apparently dominated by Strombidium sp. in summer. Pico- and nanophytoplankton had a relatively greater growth rate than microzooplankton both in spring and summer. The growth rate and grazing mortality rate were 0.18 similar to 0.44 and 0.12 similar to 1.47 d(-1) for the total phytoplankton and 0.20 similar to 0.55 and 0.21 similar to 0.37 d-1 for nanophytoplankton in spring respectively. In summer, the growth rate and grazing mortality rate were 0.38 similar to 0.71 and 0.27 similar to 0.60 d-1 for the total phytoplankton and 0.11 similar to 1.18 and 0.41 similar to 0.72 d(-1) for nano- and microphytoplankton respectively. The carbon flux consumed by microzooplankton per day was 7.68 similar to 39.81 mg/m(3) in spring and 12.03 similar to 138.22 mg/m(3) in summer respectively. Microzooplankton ingested 17.56%similar to 92.19% of the phytoplankton standing stocks and 31.77%similar to 467.88% of the potential primary productivity in spring; in contrast, they ingested 34.60%similar to 83.04% of the phytoplankton standing stocks and 71.28%similar to 98.80% of the potential primary productivity in summer. Pico- and nanophytoplankton appeared to have relatively greater rates of growth and grazing mortality than microphytoplankton during the experimental period. The grazing rate of microzooplankton in summer was a little bit greater than that in spring because of the relatively higher incubation temperature and different dominant microzooplankton species. Microzooplankton preferred ingesting nanophytoplankton to microphytoplankton in spring, while they preferred ingesting picophytoplankton to nanophytoplankton and microphytoplankton in summer. Compared with the results of dilution experiments performed in various waters worldwide, the results are in the middle range.

Seasonal variations in growth and clearance rate of the Zhikong scallop Chlamys farreri suspended in the deep water of Haizhou Bay, China

The growth and survival of the Zhikong scallop Chlamys farreri suspended in deep water of Haizhou Bay were studied from July 2007 to June 2008, and the biodeposition method was used to estimate the clearance rate of C. farreri under field conditions. Results showed that the scallop grew fast during all the culture time, with the exception of summer. The condition index of the scallop increased with time and reached the highest value in spring of the second year. The survival of scallops was 60.8 +/- A 3.9% at the end of this study, mortality occurring mainly during the summer and autumn of the first year. The clearance rate fluctuated obviously with season,with the highest value in September 2007, and the lowest value in March 2008. Factors accounting for variations in growth and clearance rate of scallops are also discussed.