海洋硅藻和綠潮藻光合特性對海洋酸化以及其他環(huán)境因子的響應(yīng).pdf

1、While increasing atmospheric CO2 concentration and associated ocean acidificationhave been predicted to stimulate marine primary production, little is known about theinterplay between ocean acidification and other climat

2、e change parameters, such asshoaling of upper mixing layer (UML), associated with global warming.Here, weshowed that the high CO2-grown cells showed higher growth rates at the lower lightlevels but reversed to much reduc

3、ed rates under the higher light levels in all thediatoms tested, with reduced PAR threshold at which it becomes excessive andincreased NPQ, when the diatoms, Phaeodactylum tricornutum, Thalassiosirapseudonana and Skeleto

4、nema costatum grown under different levels (5-100％) ofsolar radiation, mimicking the PAR doses received by the cells during mixing withindifferent depths of UML.Future acidified and shoaled upper oceans will lead toincre

5、ased light stress for phytoplankton, would subsequently influence marinebiological CO2 pump and biogeochemical processes.
　　It is important to understand the combined or interactive effects of multiple futureclimate c

6、hange variables on phytoplankton in order to assess the net ecologicalinfluences of future ocean changes.We used a simultaneous multivariate “clusterexperiment” treatment approach to investigate the responses of growth r

7、ates,chlorophyll a, biogenic silica (BSi), and particulate organic carbon (POC) andnitrogen (PON) contents of the diatoms Thalassiosira pseudonana and Skeletonemacostatum grown under different cluster regimes of solar ra

8、diation, nutrients, and pCO2(pH).These conditions were chosen to simulate future expected reductions in thethickness of the upper mixed layer that will lead to increased light exposures anddecreased transport of nutrient

9、s, as well as CO2 increases and pH declines due toocean acidification.Present-day (cluster l), mid-century (cluster 2) and end-century(cluster 3) scenarios were simulated following future projections based on the IPCCA 1

10、F 1 scenario (IPCC Climate change 2001).Our results showed that growth ratesdecreased by 8-18％ and chl a contents by 44-58％in cluster 2, and by 79-82％ and73-83％ in cluster 3, respectively, compared to cluster 1.And Cellu

11、lar POCsignificantly increased in both species, being 1.3-1.4 times and 1.4-2.1 times higherunder cluster 2 and cluster 3, respectively, compared with the cells grown undercluster 1.However, no significant difference was

12、 found in cellular PON content,leading to increased C/N ratios under future conditions in both species.Cellular BSicontent showed no significant differences between treatments in T.pseudonana, butincreased by 40％ and 100

13、％ in S.costatum under cluster 2 and cluster 3, respectively.Our results suggest that enhanced stratification may interact with ocean acidificationto influence diatom-relatedbiogeochemical processes by affecting their gro

14、wth andbiochemical compositions in species-specific ways, although other global changevariables not examined such as ocean warming could also modify these responses. Marine green plants, though sharing similar photosyn

15、thetic machinery withterrestrial higher plants, may show differential responses to increasing CO2concentration due to associated seawater acidification.When the cosmopolitan greenalga, Ulva prolifera, was grown from its

16、zoospore, under elevated CO2 concentrationof 1000 tatm for over 50 days, it reduced its maximal photosynthetic capacity andlight use efficiency as well as its ability to dissipate excessive light energy, thoughacclimatio

17、n to the elevated CO2 led to higher electron transfer rate.Along with thedecreased photosynthetic affinity for HCO3-or/and CO2, photorespiration increased,Chl a and Chl b contents decreased and carotenoids contents incre

18、ased remarkablyunder the elevated CO2.The increased photorespiration and carotenoid contents,together with the down-regulated CCM, implies that the green alga increased itsdefensive strategy against CO2-driven seawater a

19、cidification at the cost of reducedratio of carboxylation to oxygenation, which contrasts to reduced photorespirationobserved in its terrestrial green partners.From a physiological evolutionary point ofview, ancient ocea