pH effect on the susceptibility to parasitoid infection in the marine diatom Coscinodiscus spp. (Bacillariophyceae)

Kühn, Stefanie F.; Köhler-Rink, Stephanie

doi:10.1007/s00227-008-0904-4

Cited by 9 publications

(5 citation statements)

References 31 publications

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“…Yet, flow changes are well known to severely impact microenvironmental pH levels of photosymbiotic foraminifera ( Figure 2 , [15] ) and other phototrophs in light [19] , [20] , [63] . The changes in surface pH are especially severe within static culture experiments, where ΔpH can change up to >1 unit (>5 nM of H + , Figure 2 , [15] , [71] ). Zero-flow conditions for ocean acidification studies should therefore be avoided, as they are ecologically unrealistic and also confuse the carbonate chemistry of the intended pCO 2 perturbation, causing unrealistically high/low microenvironmental pH conditions in light/dark, despite increased DIC levels.…”

Section: Discussionmentioning

confidence: 99%

The O2, pH and Ca2+ Microenvironment of Benthic Foraminifera in a High CO2 World

et al. 2012

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Ocean acidification (OA) can have adverse effects on marine calcifiers. Yet, phototrophic marine calcifiers elevate their external oxygen and pH microenvironment in daylight, through the uptake of dissolved inorganic carbon (DIC) by photosynthesis. We studied to which extent pH elevation within their microenvironments in daylight can counteract ambient seawater pH reductions, i.e. OA conditions. We measured the O2 and pH microenvironment of four photosymbiotic and two symbiont-free benthic tropical foraminiferal species at three different OA treatments (∼432, 1141 and 2151 µatm pCO2). The O2 concentration difference between the seawater and the test surface (ΔO2) was taken as a measure for the photosynthetic rate. Our results showed that O2 and pH levels were significantly higher on photosymbiotic foraminiferal surfaces in light than in dark conditions, and than on surfaces of symbiont-free foraminifera. Rates of photosynthesis at saturated light conditions did not change significantly between OA treatments (except in individuals that exhibited symbiont loss, i.e. bleaching, at elevated pCO2). The pH at the cell surface decreased during incubations at elevated pCO2, also during light incubations. Photosynthesis increased the surface pH but this increase was insufficient to compensate for ambient seawater pH decreases. We thus conclude that photosynthesis does only partly protect symbiont bearing foraminifera against OA.

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Section: Discussionmentioning

confidence: 99%

The O2, pH and Ca2+ Microenvironment of Benthic Foraminifera in a High CO2 World

et al. 2012

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“…They can serve as a structural element for defense against predators [3] , or be used to counter-balance turgor pressure or regulate exchanges with the environment [4] . They also act as an effective pH buffer [5] , and protect cells against infection by parasites [6] . Therefore, disturbances in diatoms' ability to build up their siliceous skeleton is expected to have a large impact on cell growth, which can in turn impact the silicon cycle [7] , [8] .…”

Section: Introductionmentioning

confidence: 99%

Multiparametric Analyses Reveal the pH-Dependence of Silicon Biomineralization in Diatoms

et al. 2012

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Diatoms, the major contributors of the global biogenic silica cycle in modern oceans, account for about 40% of global marine primary productivity. They are an important component of the biological pump in the ocean, and their assemblage can be used as useful climate proxies; it is therefore critical to better understand the changes induced by environmental pH on their physiology, silicification capability and morphology. Here, we show that external pH influences cell growth of the ubiquitous diatom Thalassiosira weissflogii, and modifies intracellular silicic acid and biogenic silica contents per cell. Measurements at the single-cell level reveal that extracellular pH modifications lead to intracellular acidosis. To further understand how variations of the acid-base balance affect silicon metabolism and theca formation, we developed novel imaging techniques to measure the dynamics of valve formation. We demonstrate that the kinetics of valve morphogenesis, at least in the early stages, depends on pH. Analytical modeling results suggest that acidic conditions alter the dynamics of the expansion of the vesicles within which silica polymerization occurs, and probably its internal pH. Morphological analysis of valve patterns reveals that acidification also reduces the dimension of the nanometric pores present on the valves, and concurrently overall valve porosity. Variations in the valve silica network seem to be more correlated to the dynamics and the regulation of the morphogenesis process than the silicon incorporation rate. These multiparametric analyses from single-cell to cell-population levels demonstrate that several higher-level processes are sensitive to the acid-base balance in diatoms, and its regulation is a key factor for the control of pattern formation and silicon metabolism.

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“…For example, pH and O 2 gradients near the cell could be affected by episodic versus sustained boundary layer replacement. Both carbon speciation [45] and even parasite susceptibility [46] may change in response to periodic versus sustained sinking as it impacts pH gradients near the cell.…”

mentioning

confidence: 99%

Dynamic sinking behaviour in marine phytoplankton: rapid changes in buoyancy may aid in nutrient uptake

et al. 2016

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Phytoplankton sinking is an important property that can determine community composition in the photic zone and material loss to the deep ocean. To date, studies of diatom suspension have relied on bulk measurements with assumptions that bulk rates adequately capture the essential characteristics of diatom sinking. However, recent work has illustrated that individual diatom sinking rates vary considerably from the mean bulk rate. In this study, we apply high-resolution optical techniques, individual-based observations of diatom sinking and a recently developed method of flow visualization around freely sinking cells. The results show that in both field samples and laboratory cultures, some large species of centric diatoms are capable of a novel behaviour, whereby cells undergo bursts of rapid sinking that alternate with near-zero sinking rates on the timescales of seconds. We also demonstrate that this behaviour is under direct metabolic control of the cell. We discuss these results in the context of implications for nutrient flux to the cell surface. While nutrient flux in large diatoms increases during fast sinking, current mass transport models cannot incorporate the unsteady sinking behaviour observed in this study. However, large diatoms appear capable of benefiting from the enhanced nutrient flux to their surface during rapid sinking even during brief intervening periods of near-zero sinking rates.

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pH effect on the susceptibility to parasitoid infection in the marine diatom Coscinodiscus spp. (Bacillariophyceae)

Cited by 9 publications

References 31 publications

The O2, pH and Ca2+ Microenvironment of Benthic Foraminifera in a High CO2 World

The O2, pH and Ca2+ Microenvironment of Benthic Foraminifera in a High CO2 World

Multiparametric Analyses Reveal the pH-Dependence of Silicon Biomineralization in Diatoms

Dynamic sinking behaviour in marine phytoplankton: rapid changes in buoyancy may aid in nutrient uptake

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