Jolanda Verspagen

Phytoplankton ecologist at University of Amsterdam

[Jolanda Verspagen @JMHVerspagen]

@DedmerW @duan_zhipeng @PetraVisser10 @niooknaw Happy to see it works again!
Greetings from #SEFS11 in Zagreb.

[Jolanda Verspagen @JMHVerspagen]

@bjrobson @Frereop @GriffithARI The fact that Tricho only has the high-flux bicarbonate transporter BicA (Price et al 2008) may explain why it positively responds to high CO2. The response is similar to the increased competitive ability of BicA containing Microcystis strains (Sandrini et al 2016,) #cyanoTC2018

[Jolanda Verspagen @JMHVerspagen]

6 #cyanoTC2018 To conclude: rising CO2 concentrations are expected to intensify phytoplankton blooms and change bloom composition, favoring species with high-flux carbon uptake transporters. Future blooms will be different! Feel free to tweet questions! @GriffithARI

[Jolanda Verspagen @JMHVerspagen]

@yunni65488736 Rising CO2 will not change alkalinity directly. CO2 is not in the alkalinity equation. More CO2 will shift carbon speciation, but alkalinity will remain the same. Other processes related to rising CO2 (e.g. increased NO3- assimilation) may increase alkalinity.#cyanoTC2018

[Jolanda Verspagen @JMHVerspagen]

3 #cyanoTC2018 The model was extrapolated to lake dimensions and run at a range of pCO2 and alkalinity. The model predicts that increasing pCO2 intensifies blooms in most lakes, particularly in lakes with low alkalinity: i.e. in lakes with low inorganic carbon concentrations.

[Jolanda Verspagen @JMHVerspagen]

@bjrobson @Frereop @GriffithARI Eichner et al. (2015) show that Trichodesmium completely relies on bicarbonate: net CO2 uptake is negative at both ambient and high CO2. Expansion of Tricho might also be a temperature effect (Spatharis et al 2012). #cyanoTC2018

[Jolanda Verspagen @JMHVerspagen]

@Frereop @GriffithARI Not sure: the relative abundance of cyanobacteria does indeed seem to decrease, but not in all lakes. Also, since total phytoplankton abundances will increase in eutrophic systems, there may still be a lot of cyanobacteria in a high CO2 world. #cyanoTC2018

[Jolanda Verspagen @JMHVerspagen]

@yunni65488736 Yes, so far, we just used models to predict what happens in lakes with different alkalinity. But these models do not yet contain the diversity of different carbon uptake mechanisms present within phytoplankton. It is a good idea for future research! #cyanoTC2018

[Jolanda Verspagen @JMHVerspagen]

@yunni65488736 No, I have not investigated the response of phytoplankton in waterbodies with different alkalinity directly, but I am currently involved in an analysis of a large dataset into the response of phytoplankton to high CO2 in which alkalinity is an important factor. #cyanoTC2018

[Jolanda Verspagen @JMHVerspagen]

@Frereop @GriffithARI I do think non-bicarbonate users will be more competitive in a high CO2 world. There is some evidence that Chrysophytes fossils have been increasing in recent decades (Wolfe et al 2013), and excitingly, our own NEW research is pointing in the same direction! #cyanoTC2018

[Jolanda Verspagen @JMHVerspagen]

5 #cyanoTC2018 In mixtures of Microcystis strains with different carbon uptake genotypes, strains with the high-flux bicarbonate transporter bicA became stronger competitors at high pCO2, both in lab cultures and in a natural bloom.

[Jolanda Verspagen @JMHVerspagen]

4 #cyanoTC2018 In lab competition experiments at low and high pCO2 (100 vs 1000 ppm) between the cyanobacterium Microcystis and 3 green algae, Monoraphidium always lost, while Scendesmus always won. Microcystis however, became a stronger competitor at high pCO2.

[Jolanda Verspagen @JMHVerspagen]

2 #cyanoTC2018 In lab cultures, phytoplankton population density strongly increased in high compared to low pCO2 (1200 vs 200 ppm). In low pCO2 cultures, [CO2] was strongly depleted, and pH reached high levels. A model fitted the experimental data well.

[Jolanda Verspagen @JMHVerspagen]

1 #cyanoTC2018 Rising atmospheric CO2 (pCO2) levels increase dissolved CO2 concentrations. Phytoplankton use HCO3- as a carbon source to overcome low CO2 concentrations, but species differ in carbon uptake genotypes. We studied how rising pCO2 changes bloom size and composition.

[Jolanda Verspagen @JMHVerspagen]

@manxiaogu Hi Man, twitter seems to work now, but I cannot upload gifs in tweetdeck, so I'll tweet realtime. I'll set the alarmclock a bit earlier!