Combined Effects of Temperature, Irradiance, and pH on Teleaulax amphioxeia (Cryptophyceae) Physiology and Feeding Ratio For Its Predator Mesodinium rubrum (Ciliophora)¹

Abstract

The cryptophyte Teleaulax amphioxeia is a source of plastids for the ciliate Mesodinium rubrum and both organisms are members of the trophic chain of several species of Dinophysis. It is important to better understand the ecology of organisms at the first trophic levels before assessing the impact of principal factors of global change on Dinophysis spp. Therefore, combined effects of temperature, irradiance, and pH on growth rate, photosynthetic activity, and pigment content of a temperate strain of T. amphioxeia were studied using a full factorial design (central composite design 23*) in 17 individually controlled bioreactors. The derived model predicted an optimal growth rate of T. amphioxeia at a light intensity of 400 μmol photons · m−2 · s−1, more acidic pH (7.6) than the current average and a temperature of 17.6°C. An interaction between temperature and irradiance on growth was also found, while pH did not have any significant effect. Subsequently, to investigate potential impacts of prey quality and quantity on the physiology of the predator, M. rubrum was fed two separate prey: predator ratios with cultures of T. amphioxeia previously acclimated at two different light intensities (100 and 400 μmol photons · m−2 s−1). M. rubrum growth appeared to be significantly dependent on prey quantity while effect of prey quality was not observed. This multi‐parametric study indicated a high potential for a significant increase of T. amphioxeia in future climate conditions but to what extent this would lead to increased occurrences of Mesodinium spp. and Dinophysis spp. should be further investigated.

Physiological response of an Antarctic cryptophyte to increasing temperature, CO2, and irradiance

“…On the other hand, it was reported that G. cryophila was not negatively affected by high pCO 2 (Trimborn et al 2019; Camoying et al 2022), similar to what has been observed for cryptophytes in general when natural phytoplankton were grown under elevated pCO 2 levels (Sommer et al 2015; Schulz et al 2017; Donahue et al 2019). This is in line with the findings that cryptophytes are able to grow within a broad pH range (i.e., at both lower and upper extreme of the pH spectrum, Weisse and Stadler 2006; Gaillard et al 2020).…”

“…5C). Similar to the temperate cryptophyte Teleaulax amphioxeia (Gaillard et al 2020), G. cryophila was mainly influenced by temperature and irradiance and not by high pCO 2 . Based on our results, it becomes evident that the previously observed negative effects of high light alone on growth of the cryptophyte were alleviated by warming.…”

The effect of short-term temperature exposure on vital physiological processes of mixoplankton and protozooplankton

“…Thus, this procedure may have increased their tolerance and performance to higher temperatures (Chakravarti et al, 2017). Gaillard et al (2020) found similar growth performances for T. amphioxeia in response to temperature. Thus, the combined assessment of our and other studies suggests that M. rubrum and its prey are tightly coupled in terms of thermal tolerance.…”

Understanding and Managing Harmful Algal Bloom Risks in a Changing Climate: Lessons From the European CoCliME Project

“…In the NE Atlantic (France) case study, the target for climate services was Dinophysis, a highly toxic HAB species, that even at low biomass can contaminate shellfish and cause shellfish poisoning if consumed by humans. For the natural scientists in this case, a key focus was on filling knowledge gaps on small scale ocean processes affecting the bloom and clarifying the adaptation of essential Dinophysis food web components to changing light, temperature and pH conditions (Gaillard et al, 2020). Knowledge at this small scale can be combined with physical oceanographic numerical modeling of future scenarios to progress climate service development (Ralston and Moore, 2020).…”