Long photoperiods sustain high pH in Arctic kelp forests

Krause‐Jensen, Dorte; Marbà, Núria; Sanz-Martín, Marina; Hendriks, Iris E.; Thyrring, Jakob; Carstensen, Jacob; Sejr, Mikael K.; Duarte, Carlos M.

doi:10.1126/sciadv.1501938

Cited by 70 publications

(51 citation statements)

References 54 publications

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“…Although experimental studies have shown soft calms to be susceptible to aragonite dissolution from acidification (Gazeau et al, ; Ries et al, ), it is difficult to say how those experiments relate to the natural environment that the clams actually live in. Other lines of research have shown that vulnerability to acidification also depends on food supply (Ramajo et al, ) and the ability for the surrounding habitat to regulate pH (e.g., Krause‐Jensen et al, ). Nevertheless, since our sampling coincides with the clam harvesting depth and was conducted during the season with expected minimum pH values, we felt it would be useful to report the calcium carbonate saturation states based on our measured carbon system parameters (Table ).…”

Section: Discussionmentioning

confidence: 99%

Response of the Arctic Marine Inorganic Carbon System to Ice Algae and Under‐Ice Phytoplankton Blooms: A Case Study Along the Fast‐Ice Edge of Baffin Bay

et al. 2019

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Past research in seasonally ice‐covered Arctic seas has suggested that ice algae play a role in reducing dissolved inorganic carbon (DIC) during spring, preconditioning surface waters to low dissolved CO2 (pCO2sw), and uptake of atmospheric CO2 during the ice‐free season. The potential role of under‐ice phytoplankton blooms on DIC and pCO2sw has not often been considered. In this study we examined the inorganic carbon system beneath landfast sea ice starting midway through a bottom ice algae bloom and concluding in the early stages of an under‐ice phytoplankton bloom. During most of the ice algae bloom we observed a slight increase in DIC/pCO2sw in surface waters, as opposed to the expected reduction. Biomass calculations confirm that the role of ice algae on DIC/pCO2sw in the study region were minor and that this null result may be widely applicable. During snow melt, we observed an under‐ice phytoplankton bloom (to 10 mg/m3 Chl a) that did reduce DIC and pCO2sw. We conclude that under‐ice phytoplankton blooms are an important biological mechanism that may predispose some Arctic seas to act as a CO2 sink at the time of ice breakup. We also found that pCO2sw was undersaturated at the study location even at the beginning of our sampling period, consistent with several other studies that have measured under‐ice pCO2sw in late winter or early spring. Finally, we present the first measurements of carbonate saturation states for this region, which may be useful for assessing the vulnerability of a local soft‐shelled clam fishery to ocean acidification.

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Section: Discussionmentioning

confidence: 99%

Response of the Arctic Marine Inorganic Carbon System to Ice Algae and Under‐Ice Phytoplankton Blooms: A Case Study Along the Fast‐Ice Edge of Baffin Bay

et al. 2019

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“…Generally, the rate and amplitude of pH changes are inversely proportional to the spatial scale considered, i.e., small scale pH fluctuations can be fast (sec‐min) and dramatic (1–3 units) in the diffusive boundary layer of macroalgal thalli whereas large‐scale seasonal pH fluctuations in coastal waters are much slower (weeks‐months) and less strong (< 1 unit) (Wahl et al ). In addition, macroalgal photosynthesis may raise the mean pH in their vicinity, an effect which increases with increasing daily photoperiod (Krause‐Jensen et al ).…”

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confidence: 99%

Macroalgae may mitigate ocean acidification effects on mussel calcification by increasing pH and its fluctuations

Wahl

Covachã

Saderne

et al. 2017

Limnology & Oceanography

121

131

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Ocean acidification (OA) is generally assumed to negatively impact calcification rates of marine organisms. At a local scale however, biological activity of macrophytes may generate pH fluctuations with rates of change that are orders of magnitude larger than the long-term trend predicted for the open ocean. These fluctuations may in turn impact benthic calcifiers in the vicinity. Combining laboratory, mesocosm and field studies, such interactions between OA, the brown alga Fucus vesiculosus, the sea grass Zostera marina and the blue mussel Mytilus edulis were investigated at spatial scales from decimetres to 100s of meters in the western Baltic. Macrophytes increased the overall mean pH of the habitat by up to 0.3 units relative to macrophytefree, but otherwise similar, habitats and imposed diurnal pH fluctuations with amplitudes ranging from 0.3 to more than 1 pH unit. These amplitudes and their impact on mussel calcification tended to increase with increasing macrophyte biomass to bulk water ratio. At the laboratory and mesocosm scales, biogenic pH fluctuations allowed mussels to maintain calcification even under acidified conditions by shifting most of their calcification activity into the daytime when biogenic fluctuations caused by macrophyte activity offered temporal refuge from OA stress. In natural habitats with a low biomass to water body ratio, the impact of biogenic pH fluctuations on mean calcification rates of M. edulis was less pronounced. Thus, in dense algae or seagrass habitats, macrophytes may mitigate OA impact on mussel calcification by raising mean pH and providing temporal refuge from acidification stress.

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“…The concept of chemical refuge has been raised in response to major concerns about the negative effects of OA on calcifying invertebrates (Buapet et al 2013;Greiner et al 2018;Groner et al 2018;Hendriks 2014;Krause-Jensen et al 2016;Unsworth et al 2012). In coastal ecosystems, macroalgal beds are characterised by intense metabolic activity capable of modifying their surrounding environment (Cornwall et al 2013(Cornwall et al , 2014Dayton 1985;Hofmann et al 2011;Hurd 2015).…”

Section: Macrophytes As Oa Refuges For Calcifying Marine Organismsmentioning

confidence: 99%

Co-culture in marine farms: macroalgae can act as chemical refuge for shell-forming molluscs under an ocean acidification scenario

2019

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With ongoing climate change, aquaculture faces environmental challenges similar to those of natural ecosystems. These include increasing stress for calcifying species, e.g. macroalgae and shellfish. In this context, ocean acidification (OA) has the potential to affect important socioeconomic activities, including shellfish aquaculture, due to changes in the seawater carbonate system. However, coastal environments are characterised by strong diurnal pH fluctuations associated with the metabolic activity of macroalgae; that is, photosynthesis and respiration. This suggests that calcifying organisms that inhabit these ecosystems are adapted to this fluctuating pH environment. Macrophyte-dominated environments may have the potential to act as an OA buffering system in the form of a photosynthetic footprint, by reducing excess of CO 2 and increasing the seawater pH and Ω arg. This can support calcification and other threatened physiological processes of calcifying organisms under a reduced pH environment. Because this footprint is supportive beyond the macroalgal canopy spatial area, this chemical refuge mechanism can be applied to support shellfish aquaculture, e.g. mussels. However, this approach should be tested in commercial shellfish farms to determine critical aspects of implementation. This includes critical factors such as target species and productivity rates. The degree of OA buffering capacity caused by the metabolic activity of macroalgae might depend on community structure and hydrodynamic conditions, creating site-specific responses. This concept might aid the development of future adaptive strategies, supporting marine ecological planning for the mussel aquaculture industry in Chile.

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Long photoperiods sustain high pH in Arctic kelp forests

Abstract: In situ measurements and aquaria manipulation show that long summer days lead to sustained high pH in Arctic kelp forests.

Cited by 70 publications

References 54 publications

Response of the Arctic Marine Inorganic Carbon System to Ice Algae and Under‐Ice Phytoplankton Blooms: A Case Study Along the Fast‐Ice Edge of Baffin Bay

Response of the Arctic Marine Inorganic Carbon System to Ice Algae and Under‐Ice Phytoplankton Blooms: A Case Study Along the Fast‐Ice Edge of Baffin Bay

Macroalgae may mitigate ocean acidification effects on mussel calcification by increasing pH and its fluctuations

Co-culture in marine farms: macroalgae can act as chemical refuge for shell-forming molluscs under an ocean acidification scenario

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