High pH in shallow-water macroalgal habitats

Middelboe, Anne Lise; Hansen, Per Juel

doi:10.3354/meps338107

Cited by 104 publications

(98 citation statements)

References 32 publications

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“…This is especially true in productive freshwaters where high photosynthetic demand can produce extremely low concentrations of CO 2 in surface water during the summer (Maberly 1996), potentially producing an ecological niche for species with constitutive or facultative CCMs. The same can also be true in productive marine systems (Middelboe and Hansen 2007).…”

Section: Introductionmentioning

confidence: 71%

Algal and aquatic plant carbon concentrating mechanisms in relation to environmental change

et al. 2011

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Abstract.Carbon dioxide concentrating mechanisms (also known as inorganic carbon concentrating mechanisms; both abbreviated as CCMs) presumably evolved under conditions of low CO 2 availability. However, the timing of their origin is unclear since there are no sound estimates from molecular clocks, and even if there were, there are no proxies for the functioning of CCMs. Accordingly, we cannot use previous episodes of high CO 2 (e.g. the Palaeocene-Eocene Thermal Maximum) to indicate how organisms with CCMs responded. Present and predicted environmental change in terms of increased CO 2 and temperature are leading to increased CO 2 and HCO 3 -and decreased CO 3 2-and pH in surface seawater, as well as decreasing the depth of the upper mixed layer and increasing the degree of isolation of this layer with respect to nutrient flux from deeper waters. The outcome of these forcing factors is to increase the availability of inorganic carbon, photosynthetic active radiation (PAR) and ultraviolet B radiation (UVB) to aquatic photolithotrophs and to decrease the supply of the nutrients (combined) nitrogen and phosphorus and of any non-aeolian iron. The influence of these variations on CCM expression has been examined to varying degrees as acclimation by extant organisms. Increased PAR increases CCM expression in terms of CO 2 affinity, while increased UVB has a range of effects in the organisms examined; little relevant information is available on increased temperature. Decreased combined nitrogen supply generally increases CO 2 affinity, decreased iron availability increases CO 2 affinity, and decreased phosphorus supply has varying effects on the organisms examined. There are few data sets showing interactions among the observed changes, and even less information on genetic (adaptation) 2 changes in response to the forcing factors. In freshwaters, changes in phytoplankton species composition may alter with environmental change with consequences for frequency of species with or without CCMs. The information available permits less predictive power as to the effect of the forcing factors on CCM expression than for their overall effects on growth. CCMs are currently not part of models as to how global environmental change has altered, and is likely to further alter, algal and aquatic plant primary productivity.Keywords CO 2 concentrating mechanism -combined nitrogen -inorganic carboniron -mixing depth -photosynthetically active radiation -phosphorus -temperature -UVA-UVB Abbreviations CCM CO 2 concentrating mechanism DOC Dissolved organic carbon PAR Photosynthetically active radiation (400-700 nm)Rubisco Ribulose bisphosphate carboxylase-oxygenase UVA Ultraviolet A radiation (320-400 nm) UVB Ultraviolet B radiation (280-320 nm)

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Section: Introductionmentioning

confidence: 71%

Algal and aquatic plant carbon concentrating mechanisms in relation to environmental change

et al. 2011

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“…This confers these plants the potential to improve the conditions for calcifiers by increasing pH during their productive period, which is a particularly important function a future, more acidified ocean where lowered saturation state for carbonate minerals may compromise calcifying species (Orr et al, 2005). Dense macrophyte beds may, thus, upregulate pH by up to 1 unit during daytime (Middelboe and Hansen, 2007). Such increase in pH by macroalgal production is partially offset by community respiration during nighttime and periods of net decomposition and their net effect on pH depends on the temporal and spatial coupling of photosynthesis and community respiration as well as on burial of macroalgal detritus.…”

Section: Ecosystem Functions and Services By Arctic Vegetated Coastalmentioning

confidence: 99%

Expansion of vegetated coastal ecosystems in the future Arctic

2014

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Warming occurs particularly fast in the Arctic and exerts profound effects on arctic ecosystems. Sea ice-associated ecosystems are projected to decline but reduced arctic sea ice cover also increases the solar radiation reaching the coastal seafloors with the potential for expansion of vegetated habitats, i.e., kelp forests and seagrass meadows. These habitats support key ecosystem functions, some of which may mitigate effects of climate change. Therefore, the likely expansion of vegetated coastal habitats in the Arctic will generate new productive ecosystems, offer habitat for a number of invertebrate and vertebrate species, including provision of refugia for calcifiers from possible threats from ocean acidification, contribute to enhance CO 2 sequestration and protect the shoreline from erosion. The development of models allowing quantitative forecasts of the future of vegetated arctic ecosystems requires that key hypotheses underlying such forecasts be tested. Here we propose a set of three key testable hypotheses along with a research agenda for testing them using a broad diversity of approaches, including analyses of paleo-records, space-for-time substitutions and experimental studies. The research agenda proposed would provide a solid underpinning to guide forecasts on the spread of marine macrophytes onto the Arctic with climate change and contribute to balance our understanding of climate change impacts on the arctic ecosystem through a focus on the role of engineering species. Anticipating these changes in ecosystem structure and function is key to develop managerial strategies to maximize these ecosystem services in a future warmer Arctic.

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“…Thus, such temperature increase would induce in 2100 a pH variation ranging only from -0.19 to -0.37 pH unit. The amplitude of such pH decrease would, consequently, remain within the observed amplitude of the seasonal variations (Middelboe & Hansen, 2007;Abdelmongy & ElMoselhy, 2015). Similar results were observed in recent global modeling studies (Orr et al, 2005;Somot et al, 2008;Orr, 2011;Palmiéri et al, 2015), which took into account the variations in ocean circulation, seawater temperature, and air-sea CO 2 fluxes.…”

Section: Acidification Estimates Of the Mediterranean Seamentioning

confidence: 99%

Thermodynamic Forecasts of the Mediterranean Sea Acidification

et al. 2016

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Anthropogenic CO2 is a major driver of the present ocean acidification. This latter is threatening the marine ecosystems and has been identified as a major environmental and economic menace. This study aims to forecast from the thermodynamic equations, the acidification variation (ΔpH) of the Mediterranean waters over the next few decades and beyond this century. In order to do so, we calculated and fitted the theoretical values based upon the initial conditions from data of the 2013 MedSeA cruise. These estimates have been performed both for the Western and for the Eastern basins based upon their respective physical (temperature and salinity) and chemical (total alkalinity and total inorganic carbon) properties. The results allow us to point out four tipping points, including one when the Mediterranean Sea waters would become acid (pH<7). In order to provide an associated time scale to the theoretical results, we used two of the IPCC (2007) atmospheric CO2 scenarios. Under the most optimistic scenario of the “Special Report: Emissions Scenarios” (SRES) of the IPCC (2007), the results indicate that in 2100, pH may decrease down to 0.245 in the Western basin and down to 0.242 in the Eastern basin (compared to the pre-industrial pH). Whereas for the most pessimistic SRES scenario of the IPCC (2007), the results for the year 2100, forecast a pH decrease down to 0.462 and 0.457, for the Western and for the Eastern basins, respectively. Acidification, which increased unprecedentedly in recent years, will rise almost similarly in both Mediterranean basins only well after the end of this century. These results further confirm that both basins may become undersaturated (< 1) with respect to calcite and aragonite (at the base of the mixed layer depth), only in the far future (in a few centuries).

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High pH in shallow-water macroalgal habitats

Cited by 104 publications

References 32 publications

Algal and aquatic plant carbon concentrating mechanisms in relation to environmental change

Algal and aquatic plant carbon concentrating mechanisms in relation to environmental change

Expansion of vegetated coastal ecosystems in the future Arctic

Thermodynamic Forecasts of the Mediterranean Sea Acidification

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