ORCID Profile
0000-0002-6154-4082
Current Organisation
Victoria University of Wellington
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Phycology (incl. Marine Grasses) | Other Biological Sciences | Oceanography | Chemical Oceanography | Marine Geoscience | Ecological Physiology | Global Change Biology | Isotope Geochemistry
ANZSRC Socio-Economic Objective (SEO)
Effects of Climate Change and Variability on Australia (excl. Social Impacts) | Ecosystem Adaptation to Climate Change | Physical and Chemical Conditions of Water in Coastal and Estuarine Environments | Expanding Knowledge in the Environmental Sciences | Marine Flora, Fauna and Biodiversity |
Related Links
Publications
Impacts of ocean warming and acidification on calcifying coral reef taxa: mechanisms responsible and adaptive capacity
Publisher: Portland Press Ltd.
Date: 14-02-2022
DOI: 10.1042/ETLS20210226
Abstract: Ocean warming (OW) and acidification (OA) are two of the greatest global threats to the persistence of coral reefs. Calcifying reef taxa such as corals and coralline algae provide the essential substrate and habitat in tropical reefs but are at particular risk due to their susceptibility to both OW and OA. OW poses the greater threat to future reef growth and function, via its capacity to destabilise the productivity of both taxa, and to cause mass bleaching events and mortality of corals. Marine heatwaves are projected to increase in frequency, intensity, and duration over the coming decades, raising the question of whether coral reefs will be able to persist as functioning ecosystems and in what form. OA should not be overlooked, as its negative impacts on the calcification of reef-building corals and coralline algae will have consequences for global reef accretion. Given that OA can have negative impacts on the reproduction and early life stages of both coralline algae and corals, the interdependence of these taxa may result in negative feedbacks for reef replenishment. However, there is little evidence that OA causes coral bleaching or exacerbates the effects of OW on coral bleaching. Instead, there is some evidence that OA alters the photo-physiology of both taxa. Tropical coralline algal possess shorter generation times than corals, which could enable more rapid evolutionary responses. Future reefs will be dominated by taxa with shorter generation times and high plasticity, or those in iduals inherently resistant and resilient to both marine heatwaves and OA.
Diversity of carbon use strategies in a kelp forest community: Implications for a high CO 2 ocean
Publisher: Wiley
Date: 21-03-2011
Increasing importance of crustose coralline algae to coral reef carbonate production under ongoing climate change
Publisher: Research Square Platform LLC
Date: 06-12-2022
DOI: 10.21203/RS.3.RS-2327274/V1
Abstract: Understanding the drivers of net coral reef calcium carbonate production is increasingly important as ocean warming, acidification, and other anthropogenic stressors threaten the maintenance of coral reef structures and the services these ecosystems provide. Despite intense research effort on coral reef calcium carbonate production, the inclusion of a key reef forming/accreting calcifying group, the crustose coralline algae (CCA), remains challenging both from a theoretical and practical standpoint. While corals are typically the primary reef builders of today, ongoing declines in coral cover due to a range of environmental perturbations will likely increase the relative importance of CCA and other non-scleractinian calcifying taxa to coral reef carbonate production. Here, we demonstrate that CCA are important carbonate producers that, under certain conditions, can match or even exceed the contribution of corals to coral reef carbonate production. Despite their importance, CCA are often inaccurately recorded in benthic surveys or even entirely missing from coral reef carbonate budgets. We outline several recommendations to improve the inclusion of CCA into such carbonate budgets under the ongoing climate crisis.
Marine heatwave causes unprecedented regional mass bleaching of thermally resistant corals in northwestern Australia
Publisher: Springer Science and Business Media LLC
Date: 03-11-2017
DOI: 10.1038/S41598-017-14794-Y
Abstract: In 2015/16, a marine heatwave associated with a record El Niño led to the third global mass bleaching event documented to date. This event impacted coral reefs around the world, including in Western Australia (WA), although WA reefs had largely escaped bleaching during previous strong El Niño years. Coral health surveys were conducted during the austral summer of 2016 in four bioregions along the WA coast (~17 degrees of latitude), ranging from tropical to temperate locations. Here we report the first El Niño-related regional-scale mass bleaching event in WA. The heatwave primarily affected the macrotidal Kimberley region in northwest WA (~16°S), where 4.5–9.3 degree heating weeks (DHW) resulted in 56.6–80.6% bleaching, demonstrating that even heat-tolerant corals from naturally extreme, thermally variable reef environments are threatened by heatwaves. Some heat stress (2.4 DHW) and bleaching ( %) also occurred at Rottnest Island (32°01’S), whereas coral communities at Ningaloo Reef (23°9’S) and Bremer Bay (34°25’S) were not impacted. The only other major mass bleaching in WA occurred during a strong La Niña event in 2010/11 and primarily affected reefs along the central-to-southern coast. This suggests that WA reefs are now at risk of severe bleaching during both El Niño and La Niña years.
High prevalence of diffusive uptake of CO2 by macroalgae in a temperate subtidal ecosystem
Publisher: Springer Science and Business Media LLC
Date: 05-03-2015
DOI: 10.1007/S11120-015-0114-0
Abstract: Productivity of most macroalgae is not currently considered limited by dissolved inorganic carbon (DIC), as the majority of species have CO2-concentrating mechanisms (CCM) allowing the active uptake of DIC. The alternative, diffusive uptake of CO2 (non-CCM), is considered rare (0-9% of all macroalgal cover in a given ecosystem), and identifying species without CCMs is important in understanding factors controlling inorganic carbon use by eukaryotic algae. CCM activity has higher energetic requirements than diffusive CO2 uptake, therefore when light is low, CCM activity is reduced in favour of diffusive CO2 uptake. We hypothesized that the proportional cover of macroalgae without CCMs (red and green macroalgae) would be low (<10%) across four sites in Tasmania, southern Australia at two depths (4-5 and 12-14 m) the proportion of species lacking CCMs would increase with decreasing depth the δ(13)C values of macroalgae with CCMs would be more depleted with depth. We found the proportion of non-CCM species ranged from 0 to 90% and included species from all three macroalgal phyla: 81% of red (59 species), 14% of brown (three species) and 29% of green macroalgae (two species). The proportion of non-CCM species increased with depth at three of four sites. 35% of species tested had significantly depleted δ(13)C values at deeper depths. Non-CCM macroalgae are more abundant in some temperate reefs than previously thought. If ocean acidification benefits non-CCM species, the ramifications for subtidal macroalgal assemblages could be larger than previously considered.
A unique temperate rocky coastal hydrothermal vent system (Whakaari-White Island, Bay of Plenty, New Zealand): Constraints for ocean acidification studies
Publisher: CSIRO Publishing
Date: 2020
DOI: 10.1071/MF19167
Abstract: In situ effects of ocean acidification are increasingly studied at submarine CO2 vents. Here we present a preliminary investigation into the water chemistry and biology of cool temperate CO2 vents near Whakaari–White Island, New Zealand. Water s les were collected inside three vent shafts, within vents at a distance of 2m from the shaft and at control sites. Vent s les contained both seawater pH on the total scale (pHT) and carbonate saturation states that were severely reduced, creating conditions as predicted for beyond the year 2100. Vent s les showed lower salinities, higher temperatures and greater nutrient concentrations. Sulfide levels were elevated and mercury levels were at concentrations considered toxic at all vent and control sites, but stable organic and inorganic ligands were present, as deduced from Cu speciation data, potentially mediating harmful effects on local organisms. The biological investigations focused on phytoplankton, zooplankton and macroalgae. Interestingly, we found lower abundances but higher ersity of phytoplankton and zooplankton at sites in the direct vicinity of Whakaari. Follow-up studies will need a combination of methods and approaches to attribute observations to specific drivers. The Whakaari vents represent a unique ecosystem with considerable biogeochemical complexity, which, like many other vent systems globally, require care in their use as a model of ‘future oceans’.
Decoupling between the response of coral calcifying fluid pH and calcification to ocean acidification
Publisher: Springer Science and Business Media LLC
Date: 08-08-2017
DOI: 10.1038/S41598-017-08003-Z
Abstract: Evaluating the factors responsible for differing species-specific sensitivities to declining seawater pH is central to understanding the mechanisms via which ocean acidification (OA) affects coral calcification. We report here the results of an experiment comparing the responses of the coral Acropora yongei and Pocillopora damicornis to differing pH levels (8.09, 7.81, and 7.63) over an 8-week period. Calcification of A . youngei was reduced by 35% at pH 7.63, while calcification of P . damicornis was unaffected. The pH in the calcifying fluid (pH cf ) was determined using δ 11 B systematics, and for both species pH cf declined slightly with seawater pH, with the decrease being more pronounced in P . damicornis . The dissolved inorganic carbon concentration at the site of calcification (DIC cf ) was estimated using geochemical proxies (B/Ca and δ 11 B) and found to be double that of seawater DIC, and increased in both species as seawater pH decreased. As a consequence, the decline of the saturation state at the site of calcification (Ω cf ) with OA was partially moderated by the DIC cf increase. These results highlight that while pH cf , DIC cf and Ω cf are important in the mineralization process, some corals are able to maintain their calcification rates despite shifts in their calcifying fluid carbonate chemistry.
The role of irradiance in controlling coralline algal calcification
Publisher: Wiley
Date: 25-04-2023
DOI: 10.1002/LNO.12345
Abstract: Coralline algae are an essential element of benthic ecosystems throughout the ocean's photic zone. Yet, the role of light in shaping the physiology of coralline algae from cold‐water, low‐light habitats is poorly understood. Here, we assess the calcification physiology of five cool temperate coralline algae in response to different irradiance levels over 3 months. We show that in contrast to current models focused on warmer water species, previously observed enhancement of calcification rates by photosynthesis is largely limited to lower irradiances, and that the removal of CO 2 from the calcifying fluid is not the underlying mechanism of this enhancement. Instead, this most likely occurs via two processes: (1) increased ion pumping rates to elevate the calcium carbonate saturation state in the calcifying fluid and (2) a higher daytime pH in the diffusion boundary layer that raises calcifying fluid pH. However, as irradiance increases, ion pumping becomes increasingly saturated limiting further enhancements. Our results also suggest the existence of two calcification strategies in coralline algae and indicate that magnesium incorporation is determined by the magnesium to calcium ratio in the calcifying fluid ([Mg] CF /[Ca] CF ). This study adds to our mechanistic understanding of calcification in coralline algae and fills in much needed knowledge about the role of light in controlling their physiology.
Ocean acidification reverses the positive effects of seawater pH fluctuations on growth and photosynthesis of the habitat-forming kelp, Ecklonia radiata
Publisher: Springer Science and Business Media LLC
Date: 27-05-2016
DOI: 10.1038/SREP26036
Abstract: Ocean acidification (OA) is the reduction in seawater pH due to the absorption of human-released CO 2 by the world’s oceans. The average surface oceanic pH is predicted to decline by 0.4 units by 2100. However, kelp metabolically modifies seawater pH via photosynthesis and respiration in some temperate coastal systems, resulting in daily pH fluctuations of up to ±0.45 units. It is unknown how these fluctuations in pH influence the growth and physiology of the kelp, or how this might change with OA. In laboratory experiments that mimicked the most extreme pH fluctuations measured within beds of the canopy-forming kelp Ecklonia radiata in Tasmania, the growth and photosynthetic rates of juvenile E. radiata were greater under fluctuating pH (8.4 in the day, 7.8 at night) than in static pH treatments (8.4, 8.1, 7.8). However, pH fluctuations had no effect on growth rates and a negative effect on photosynthesis when the mean pH of each treatment was reduced by 0.3 units. Currently, pH fluctuations have a positive effect on E. radiata but this effect could be reversed in the future under OA, which is likely to impact the future ecological dynamics and productivity of habitats dominated by E. radiata .
Institute Profile: Victoria University of Wellington's Coastal Ecology Laboratory—A Uniquely Situated Research Facility for Subtidal and Intertidal Biology
Publisher: Wiley
Date: 04-10-2023
DOI: 10.1002/LOB.10604
Predicting the impacts of climate change on New Zealand’s seaweed-based ecosystems
Publisher: Informa UK Limited
Date: 05-09-2023
Tolerance of three temperate macroalgal taxa to marine heatwaves of differing durations and intensities is not modulated by irradiance
Publisher: Informa UK Limited
Date: 17-10-2023
Canopy macroalgae influence understorey corallines’ metabolic control of near-surface pH and oxygen concentration
Publisher: Inter-Research Science Center
Date: 09-04-2015
DOI: 10.3354/MEPS11190
Inorganic carbon physiology underpins macroalgal responses to elevated CO2
Publisher: Springer Science and Business Media LLC
Date: 18-04-2017
DOI: 10.1038/SREP46297
Abstract: Beneficial effects of CO 2 on photosynthetic organisms will be a key driver of ecosystem change under ocean acidification. Predicting the responses of macroalgal species to ocean acidification is complex, but we demonstrate that the response of assemblages to elevated CO 2 are correlated with inorganic carbon physiology. We assessed abundance patterns and a proxy for CO 2 :HCO 3 − use (δ 13 C values) of macroalgae along a gradient of CO 2 at a volcanic seep, and examined how shifts in species abundance at other Mediterranean seeps are related to macroalgal inorganic carbon physiology. Five macroalgal species capable of using both HCO 3 − and CO 2 had greater CO 2 use as concentrations increased. These species (and one unable to use HCO 3 − ) increased in abundance with elevated CO 2 whereas obligate calcifying species, and non-calcareous macroalgae whose CO 2 use did not increase consistently with concentration, declined in abundance. Physiological groupings provide a mechanistic understanding that will aid us in determining which species will benefit from ocean acidification and why.
Coral calcification mechanisms in a warming ocean and the interactive effects of temperature and light
Publisher: Springer Science and Business Media LLC
Date: 30-03-2022
DOI: 10.1038/S43247-022-00396-8
Abstract: Ocean warming is transforming the world’s coral reefs, which are governed by the growth of marine calcifiers, most notably branching corals. Critical to skeletal growth is the corals’ regulation of their internal chemistry to promote calcification. Here we investigate the effects of temperature and light on the calcifying fluid chemistry (using boron isotope systematics), calcification rates, metabolic rates and photo-physiology of Acropora nasuta during two mesocosm experiments simulating seasonal and static temperature and light regimes. Under the seasonal regime, coral calcification rates, calcifying fluid carbonate chemistry, photo-physiology and metabolic productivity responded to both changes in temperature and light. However, under static conditions the artificially prolonged exposure to summer temperatures resulted in heat stress and a heightened sensitivity to light. Our results indicate that temperature and light effects on coral physiology and calcification mechanisms are interactive and context-specific, making it essential to conduct realistic multi-variate dynamic experiments in order to predict how coral calcification will respond to ocean warming.
Crustose coralline algae can contribute more than corals to coral reef carbonate production
Publisher: Springer Science and Business Media LLC
Date: 06-04-2023
DOI: 10.1038/S43247-023-00766-W
Abstract: Understanding the drivers of net coral reef calcium carbonate production is increasingly important as ocean warming, acidification, and other anthropogenic stressors threaten the maintenance of coral reef structures and the services these ecosystems provide. Despite intense research effort on coral reef calcium carbonate production, the inclusion of a key reef forming/accreting calcifying group, the crustose coralline algae, remains challenging both from a theoretical and practical standpoint. While corals are typically the primary reef builders of contemporary reefs, crustose coralline algae can contribute equally. Here, we combine several sets of data with numerical and theoretical modelling to demonstrate that crustose coralline algae carbonate production can match or even exceed the contribution of corals to reef carbonate production. Despite their importance, crustose coralline algae are often inaccurately recorded in benthic surveys or even entirely missing from coral reef carbonate budgets. We outline several recommendations to improve the inclusion of crustose coralline algae into such carbonate budgets under the ongoing climate crisis.
Coral adaptive capacity insufficient to halt global transition of coral reefs into net erosion under climate change
Publisher: Wiley
Date: 21-03-2023
DOI: 10.1111/GCB.16647
Abstract: Projecting the effects of climate change on net reef calcium carbonate production is critical to understanding the future impacts on ecosystem function, but prior estimates have not included corals' natural adaptive capacity to such change. Here we estimate how the ability of symbionts to evolve tolerance to heat stress, or for coral hosts to shuffle to favourable symbionts, and their combination, may influence responses to the combined impacts of ocean warming and acidification under three representative concentration pathway (RCP) emissions scenarios (RCP2.6, RCP4.5 and RCP8.5). We show that symbiont evolution and shuffling, both in idually and when combined, favours persistent positive net reef calcium carbonate production. However, our projections of future net calcium carbonate production (NCCP) under climate change vary both spatially and by RCP. For ex le, 19%–35% of modelled coral reefs are still projected to have net positive NCCP by 2050 if symbionts can evolve increased thermal tolerance, depending on the RCP. Without symbiont adaptive capacity, the number of coral reefs with positive NCCP drops to 9%–13% by 2050. Accounting for both symbiont evolution and shuffling, we project median positive NCPP of coral reefs will still occur under low greenhouse emissions (RCP2.6) in the Indian Ocean, and even under moderate emissions (RCP4.5) in the Pacific Ocean. However, adaptive capacity will be insufficient to halt the transition of coral reefs globally into erosion by 2050 under severe emissions scenarios (RCP8.5).
Flow-driven micro-scale pH variability affects the physiology of corals and coralline algae under ocean acidification
Publisher: Springer Science and Business Media LLC
Date: 06-09-2019
DOI: 10.1038/S41598-019-49044-W
Abstract: Natural variability in pH in the diffusive boundary layer (DBL), the discrete layer of seawater between bulk seawater and the outer surface of organisms, could be an important factor determining the response of corals and coralline algae to ocean acidification (OA). Here, two corals with different morphologies and one coralline alga were maintained under two different regimes of flow velocities, pH, and light intensities in a 12 flumes experimental system for a period of 27 weeks. We used a combination of geochemical proxies, physiological and micro-probe measurements to assess how these treatments affected the conditions in the DBL and the response of organisms to OA. Overall, low flow velocity did not ameliorate the negative effect of low pH and therefore did not provide a refugia from OA. Flow velocity had species-specific effects with positive effects on calcification for two species. pH in the calcifying fluid (pH cf ) was reduced by low flow in both corals at low light only. pH cf was significantly impacted by pH in the DBL for the two species capable of significantly modifying pH in the DBL. The dissolved inorganic carbon in the calcifying fluid (DIC cf ) was highest under low pH for the corals and low flow for the coralline, while the saturation state in the calcifying fluid and its proxy (FWHM) were generally not affected by the treatments. This study therefore demonstrates that the effects of OA will manifest most severely in a combination of lower light and lower flow habitats for sub-tropical coralline algae. These effects will also be greatest in lower flow habitats for some corals. Together with existing literature, these findings reinforce that the effects of OA are highly context dependent, and will differ greatly between habitats, and depending on species composition.
CARBON‐USE STRATEGIES IN MACROALGAE: DIFFERENTIAL RESPONSES TO LOWERED PH AND IMPLICATIONS FOR OCEAN ACIDIFICATION1
Publisher: Wiley
Date: 02-12-2011
DOI: 10.1111/J.1529-8817.2011.01085.X
Abstract: Ocean acidification (OA) is a reduction in oceanic pH due to increased absorption of anthropogenically produced CO2 . This change alters the seawater concentrations of inorganic carbon species that are utilized by macroalgae for photosynthesis and calcification: CO2 and HCO3 (-) increase CO3 (2-) decreases. Two common methods of experimentally reducing seawater pH differentially alter other aspects of carbonate chemistry: the addition of CO2 gas mimics changes predicted due to OA, while the addition of HCl results in a comparatively lower [HCO3 (-) ]. We measured the short-term photosynthetic responses of five macroalgal species with various carbon-use strategies in one of three seawater pH treatments: pH 7.5 lowered by bubbling CO2 gas, pH 7.5 lowered by HCl, and ambient pH 7.9. There was no difference in photosynthetic rates between the CO2 , HCl, or pH 7.9 treatments for any of the species examined. However, the ability of macroalgae to raise the pH of the surrounding seawater through carbon uptake was greatest in the pH 7.5 treatments. Modeling of pH change due to carbon assimilation indicated that macroalgal species that could utilize HCO3 (-) increased their use of CO2 in the pH 7.5 treatments compared to pH 7.9 treatments. Species only capable of using CO2 did so exclusively in all treatments. Although CO2 is not likely to be limiting for photosynthesis for the macroalgal species examined, the diffusive uptake of CO2 is less energetically expensive than active HCO3 (-) uptake, and so HCO3 (-) -using macroalgae may benefit in future seawater with elevated CO2 .
Resistance of corals and coralline algae to ocean acidification: physiological control of calcification under natural pH variability
Publisher: The Royal Society
Date: 08-08-2018
Abstract: Ocean acidification is a threat to the continued accretion of coral reefs, though some undergo daily fluctuations in pH exceeding declines predicted by 2100. We test whether exposure to greater pH variability enhances resistance to ocean acidification for the coral Goniopora sp. and coralline alga Hydrolithon reinboldii from two sites: one with low pH variability (less than 0.15 units daily Shell Island) and a site with high pH variability (up to 1.4 pH units daily Tallon Island). We grew populations of both species for more than 100 days under a combination of differing pH variability (high/low) and means (ambient pH 8.05/ocean acidification pH 7.65). Calcification rates of Goniopora sp. were unaffected by the examined variables. Calcification rates of H. reinboldii were significantly faster in Tallon than in Shell Island in iduals, and Tallon Island in iduals calcified faster in the high variability pH 8.05 treatment compared with all others. Geochemical proxies for carbonate chemistry within the calcifying fluid (cf) of both species indicated that only mean seawater pH influenced pH cf . pH treatments had no effect on proxies for Ω cf . These limited responses to extreme pH treatments demonstrate that some calcifying taxa may be capable of maintaining constant rates of calcification under ocean acidification by actively modifying Ω cf .
Macroalgal responses to ocean acidification depend on nutrient and light levels
Publisher: Frontiers Media SA
Date: 22-05-2015
Ocean acidification during prefertilization chemical communication affects sperm success
Publisher: Wiley
Date: 16-10-2019
DOI: 10.1002/ECE3.5720
pH variability at volcanic CO2 seeps regulates coral calcifying fluid chemistry
Publisher: Wiley
Date: 04-02-2022
DOI: 10.1111/GCB.16093
Abstract: Coral reefs are iconic ecosystems with immense ecological, economic and cultural value, but globally their carbonate‐based skeletal construction is threatened by ocean acidification (OA). Identifying coral species that have specialised mechanisms to maintain high rates of calcification in the face of declining seawater pH is of paramount importance in predicting future species composition, and growth of coral reefs. Here, we studied multiple coral species from two distinct volcanic CO 2 seeps in Papua New Guinea to assess their capacity to control their calcifying fluid (CF) chemistry. Several coral species living under conditions of low mean seawater pH, but with either low or high variability in seawater pH, were examined and compared with those living in ‘normal’ (non‐seep) ambient seawater pH. We show that when mean seawater pH is low but highly variable, corals have a greater ability to maintain constant pH cf in their CF, but this characteristic was not linked with changes in abundance. Within less variable low pH seawater, corals with limited reductions in pH cf at the seep sites compared with controls tended to be more abundant at the seep site than at the control site. However, this finding was strongly influenced by a single species ( Montipora foliosa ), which was able to maintain complete pH cf homeostasis. Overall, although our findings indicate that there might be an association between ecological success and greater pH cf homeostasis, further research with additional species and at more sites with differing seawater pH regimes is required to solidify inferences regarding coral ecological success under future OA.
Ocean acidification in New Zealand waters: trends and impacts
Publisher: Informa UK Limited
Date: 25-09-2017
A coralline alga gains tolerance to ocean acidification over multiple generations of exposure
Publisher: Springer Science and Business Media LLC
Date: 20-01-2020
Correction: Diffusion Boundary Layers Ameliorate the Negative Effects of Ocean Acidification on the Temperate Coralline Macroalga Arthrocardia corymbosa
Publisher: Public Library of Science (PLoS)
Date: 26-09-2014
Efficient analysis of split-plot experimental designs using model averaging
Publisher: Informa UK Limited
Date: 12-01-2023
Biological responses to environmental heterogeneity under future ocean conditions
Publisher: Wiley
Date: 25-04-2016
DOI: 10.1111/GCB.13287
Abstract: Organisms are projected to face unprecedented rates of change in future ocean conditions due to anthropogenic climate-change. At present, marine life encounters a wide range of environmental heterogeneity from natural fluctuations to mean climate change. Manipulation studies suggest that biota from more variable marine environments have more phenotypic plasticity to tolerate environmental heterogeneity. Here, we consider current strategies employed by a range of representative organisms across various habitats - from short-lived phytoplankton to long-lived corals - in response to environmental heterogeneity. We then discuss how, if and when organismal responses (acclimate/migrate/adapt) may be altered by shifts in the magnitude of the mean climate-change signal relative to that for natural fluctuations projected for coming decades. The findings from both novel climate-change modelling simulations and prior biological manipulation studies, in which natural fluctuations are superimposed on those of mean change, provide valuable insights into organismal responses to environmental heterogeneity. Manipulations reveal that different experimental outcomes are evident between climate-change treatments which include natural fluctuations vs. those which do not. Modelling simulations project that the magnitude of climate variability, along with mean climate change, will increase in coming decades, and hence environmental heterogeneity will increase, illustrating the need for more realistic biological manipulation experiments that include natural fluctuations. However, simulations also strongly suggest that the timescales over which the mean climate-change signature will become dominant, relative to natural fluctuations, will vary for in idual properties, being most rapid for CO2 (~10 years from present day) to 4 decades for nutrients. We conclude that the strategies used by biota to respond to shifts in environmental heterogeneity may be complex, as they will have to physiologically straddle wide-ranging timescales in the alteration of ocean conditions, including the need to adapt to rapidly rising CO2 and also acclimate to environmental heterogeneity in more slowly changing properties such as warming.
Physiological responses of a Southern Ocean diatom to complex future ocean conditions
Publisher: Springer Science and Business Media LLC
Date: 05-10-2015
DOI: 10.1038/NCLIMATE2811
Saturating light and not increased carbon dioxide under ocean acidification drives photosynthesis and growth inUlva rigida(Chlorophyta)
Publisher: Wiley
Date: 25-01-2015
DOI: 10.1002/ECE3.1382
Growth response of an early successional assemblage of coralline algae and benthic diatoms to ocean acidification
Publisher: Springer Science and Business Media LLC
Date: 06-05-2014
Similar controls on calcification under ocean acidification across unrelated coral reef taxa
Publisher: Wiley
Date: 08-2018
DOI: 10.1111/GCB.14379
Abstract: Ocean acidification (OA) is a major threat to marine ecosystems, particularly coral reefs which are heavily reliant on calcareous species. OA decreases seawater pH and calcium carbonate saturation state (Ω), and increases the concentration of dissolved inorganic carbon (DIC). Intense scientific effort has attempted to determine the mechanisms via which ocean acidification (OA) influences calcification, led by early hypotheses that calcium carbonate saturation state (Ω) is the main driver. We grew corals and coralline algae for 8-21 weeks, under treatments where the seawater parameters Ω, pH, and DIC were manipulated to examine their differential effects on calcification rates and calcifying fluid chemistry (Ω
Experimental design in ocean acidification research: problems and solutions
Publisher: Oxford University Press (OUP)
Date: 08-07-2015
Abstract: Ocean acidification has been identified as a risk to marine ecosystems, and substantial scientific effort has been expended on investigating its effects, mostly in laboratory manipulation experiments. However, performing these manipulations correctly can be logistically difficult, and correctly designing experiments is complex, in part because of the rigorous requirements for manipulating and monitoring seawater carbonate chemistry. To assess the use of appropriate experimental design in ocean acidification research, 465 studies published between 1993 and 2014 were surveyed, focusing on the methods used to replicate experimental units. The proportion of studies that had interdependent or non-randomly interspersed treatment replicates, or did not report sufficient methodological details was 95%. Furthermore, 21% of studies did not provide any details of experimental design, 17% of studies otherwise segregated all the replicates for one treatment in one space, 15% of studies replicated CO2 treatments in a way that made replicates more interdependent within treatments than between treatments, and 13% of studies did not report if replicates of all treatments were randomly interspersed. As a consequence, the number of experimental units used per treatment in studies was low (mean = 2.0). In a comparable analysis, there was a significant decrease in the number of published studies that employed inappropriate chemical methods of manipulating seawater (i.e. acid–base only additions) from 21 to 3%, following the release of the “Guide to best practices for ocean acidification research and data reporting” in 2010 however, no such increase in the use of appropriate replication and experimental design was observed after 2010. We provide guidelines on how to design ocean acidification laboratory experiments that incorporate the rigorous requirements for monitoring and measuring carbonate chemistry with a level of replication that increases the chances of accurate detection of biological responses to ocean acidification.
Coral resistance to ocean acidification linked to increased calcium at the site of calcification
Publisher: The Royal Society
Date: 02-05-2018
Abstract: Ocean acidification threatens the persistence of biogenic calcium carbonate (CaCO 3 ) production on coral reefs. However, some coral genera show resistance to declines in seawater pH, potentially achieved by modulating the chemistry of the fluid where calcification occurs. We use two novel geochemical techniques based on boron systematics and Raman spectroscopy, which together provide the first constraints on the sensitivity of coral calcifying fluid calcium concentrations ( ) to changing seawater pH. In response to simulated end-of-century pH conditions, Pocillopora damicornis increased to as much as 25% above that of seawater and maintained constant calcification rates. Conversely, Acropora youngei displayed less control over , and its calcification rates strongly declined at lower seawater pH. Although the role of in driving calcification has often been neglected, increasing may be a key mechanism enabling more resistant corals to cope with ocean acidification and continue to build CaCO 3 skeletons in a high-CO 2 world.
Investigating marine bio‐calcification mechanisms in a changing ocean with in vivo and high‐resolution ex vivo Raman spectroscopy
Publisher: Wiley
Date: 20-02-2019
DOI: 10.1111/GCB.14579
Effect of Ocean Acidification and pH Fluctuations on the Growth and Development of Coralline Algal Recruits, and an Associated Benthic Algal Assemblage
Publisher: Public Library of Science (PLoS)
Date: 15-10-2015
Metabolically induced pH fluctuations by some coastal calcifiers exceed projected 22nd century ocean acidification: a mechanism for differential susceptibility?
Publisher: Wiley
Date: 10-07-2011
Global declines in coral reef calcium carbonate production under ocean acidification and warming
Publisher: Proceedings of the National Academy of Sciences
Date: 10-05-2021
Abstract: The growth of coral reefs is threatened by the dual stressors of ocean warming and acidification. Despite a wealth of studies assessing the impacts of climate change on in idual taxa, projections of their impacts on coral reef net carbonate production are limited. By projecting impacts across 233 different locations, we demonstrate that the majority of coral reefs will be unable to maintain positive net carbonate production globally by the year 2100 under representative concentration pathways RCP4.5 and 8.5, while even under RCP2.6, coral reefs will suffer reduced accretion rates. Our results provide quantitative projections of how different climate change stressors will influence whole ecosystem carbonate production across coral reefs in all major ocean basins.
Concentration boundary layers around complex assemblages of macroalgae: Implications for the effects of ocean acidification on understory coralline algae
Publisher: Wiley
Date: 25-11-2012
Resistance to ocean acidification in coral reef taxa is not gained by acclimatization
Publisher: Springer Science and Business Media LLC
Date: 27-05-2019
Strategies of dissolved inorganic carbon use in macroalgae across a gradient of terrestrial influence: implications for the Great Barrier Reef in the context of ocean acidification
Publisher: Springer Science and Business Media LLC
Date: 18-07-2016
Diurnal fluctuations in seawater pH influence the response of a calcifying macroalga to ocean acidification
Publisher: The Royal Society
Date: 07-12-2013
Abstract: Coastal ecosystems that are characterized by kelp forests encounter daily pH fluctuations, driven by photosynthesis and respiration, which are larger than pH changes owing to ocean acidification (OA) projected for surface ocean waters by 2100. We investigated whether mimicry of biologically mediated diurnal shifts in pH—based for the first time on pH time-series measurements within a kelp forest—would offset or lify the negative effects of OA on calcifiers. In a 40-day laboratory experiment, the calcifying coralline macroalga, Arthrocardia corymbos a, was exposed to two mean pH treatments (8.05 or 7.65). For each mean, two experimental pH manipulations were applied. In one treatment, pH was held constant. In the second treatment, pH was manipulated around the mean (as a step-function), 0.4 pH units higher during daylight and 0.4 units lower during darkness to approximate diurnal fluctuations in a kelp forest. In all cases, growth rates were lower at a reduced mean pH, and fluctuations in pH acted additively to further reduce growth. Photosynthesis, recruitment and elemental composition did not change with pH, but δ 13 C increased at lower mean pH. Including environmental heterogeneity in experimental design will assist with a more accurate assessment of the responses of calcifiers to OA.
Effects of near‐future ocean acidification, fishing, and marine protection on a temperate coastal ecosystem
Publisher: Wiley
Date: 29-10-2014
DOI: 10.1111/COBI.12394
Abstract: Understanding ecosystem responses to global and local anthropogenic impacts is paramount to predicting future ecosystem states. We used an ecosystem modeling approach to investigate the independent and cumulative effects of fishing, marine protection, and ocean acidification on a coastal ecosystem. To quantify the effects of ocean acidification at the ecosystem level, we used information from the peer-reviewed literature on the effects of ocean acidification. Using an Ecopath with Ecosim ecosystem model for the Wellington south coast, including the Taputeranga Marine Reserve (MR), New Zealand, we predicted ecosystem responses under 4 scenarios: ocean acidification + fishing ocean acidification + MR (no fishing) no ocean acidification + fishing no ocean acidification + MR for the year 2050. Fishing had a larger effect on trophic group biomasses and trophic structure than ocean acidification, whereas the effects of ocean acidification were only large in the absence of fishing. Mortality by fishing had large, negative effects on trophic group biomasses. These effects were similar regardless of the presence of ocean acidification. Ocean acidification was predicted to indirectly benefit certain species in the MR scenario. This was because lobster (Jasus edwardsii) only recovered to 58% of the MR biomass in the ocean acidification + MR scenario, a situation that benefited the trophic groups lobsters prey on. Most trophic groups responded antagonistically to the interactive effects of ocean acidification and marine protection (46% reduced response) however, many groups responded synergistically (33% lified response). Conservation and fisheries management strategies need to account for the reduced recovery potential of some exploited species under ocean acidification, nonadditive interactions of multiple factors, and indirect responses of species to ocean acidification caused by declines in calcareous predators.
Coralline algae elevate pH at the site of calcification under ocean acidification
Publisher: Wiley
Date: 02-04-2017
DOI: 10.1111/GCB.13673
Abstract: Coralline algae provide important ecosystem services but are susceptible to the impacts of ocean acidification. However, the mechanisms are uncertain, and the magnitude is species specific. Here, we assess whether species-specific responses to ocean acidification of coralline algae are related to differences in pH at the site of calcification within the calcifying fluid/medium (pH
Understanding coralline algal responses to ocean acidification: Meta‐analysis and synthesis
Publisher: Wiley
Date: 24-10-2021
DOI: 10.1111/GCB.15899
Abstract: Ocean acidification (OA) is a major threat to the persistence of biogenic reefs throughout the world's ocean. Coralline algae are comprised of high magnesium calcite and have long been considered one of the most susceptible taxa to the negative impacts of OA. We summarize these impacts and explore the causes of variability in coralline algal responses using a review/qualitative assessment of all relevant literature, meta‐analysis, quantitative assessment of critical responses, and a discussion of physiological mechanisms and directions for future research. We find that most coralline algae experienced reduced abundance, calcification rates, recruitment rates, and declines in pH within the site of calcification in laboratory experiments simulating OA or at naturally elevated CO 2 sites. There were no other consistent physiological responses of coralline algae to simulated OA (e.g., photo‐physiology, mineralogy, and survival). Calcification/growth was the most frequently measured parameters in coralline algal OA research, and our meta‐analyses revealed greater declines in seawater pH were associated with significant decreases in calcification in adults and similar but nonsignificant trends for juveniles. Adults from the family Mesophyllumaceae also tended to be more robust to OA, though there was insufficient data to test similar trends for juveniles. OA was the dominant driver in the majority of laboratory experiments where other local or global drivers were assessed. The interaction between OA and any other single driver was often additive, though factors that changed pH at the surface of coralline algae (light, water motion, epiphytes) acted antagonistically or synergistically with OA more than any other drivers. With advances in experimental design and methodological techniques, we now understand that the physiology of coralline algal calcification largely dictates their responses to OA. However, significant challenges still remain, including improving the geographic and life‐history spread of research effort and a need for holistic assessments of physiology.
Variability in the benefits of ocean acidification to photosynthetic rates of macroalgae without CO2-concentrating mechanisms
Publisher: CSIRO Publishing
Date: 2020
DOI: 10.1071/MF19134
Abstract: Increasing concentrations of surface-seawater carbon dioxide (CO2) (ocean acidification) could favour seaweed species that currently are limited for dissolved inorganic carbon (DIC). Among them, those that are unable to use CO2-concentrating mechanisms (CCMs) to actively uptake bicarbonate (HCO3–) across the plasmalemma are most likely to benefit. Here, we assess how the DIC uptake and photosynthetic rates of three rhodophytes without CCMs respond to four seawater CO2 concentrations representing pre-industrial (280μatm), present-day (400μatm), representative concentration pathway (RCP) emissions scenario 8.52050 (650μatm) and RCP 8.52100 (1000μatm). We demonstrated that the photosynthetic rates of only one species increase between the preindustrial and end-of-century scenarios, but because of differing photosynthetic quotients (DIC taken up relative to O2 evolved), all three increase their DIC uptake rates from pre-industrial or present-day scenarios to the end-of-century scenario. These variable, but generally beneficial, responses highlight that not all species without CCMs will respond to ocean acidification uniformly. This supports past assessments that, on average, this group will likely benefit from the impacts of ocean acidification. However, more concerted efforts are now required to assess whether similar benefits to photosynthetic rates and DIC uptake are also observed in chlorophytes and ochrophytes without CCMs.
Feeding Preferences of the AbaloneHaliotis irisin Relation to Macroalgal Species, Attachment, Accessibility and Water Movement
Publisher: National Shellfisheries Association
Date: 08-2009
DOI: 10.2983/035.028.0323
An automated pH-controlled culture system for laboratory-based ocean acidification experiments
Publisher: Wiley
Date: 2010
Developing a Multiple Driver Research Strategy Using Multiple Environmental Driver Design Lab for Experiments
Publisher: Wiley
Date: 20-12-2022
DOI: 10.1002/LOB.10535
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Physiological And Environmental Controls Of Coralline Algal Calcification Under Climate Change
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End Date: 2023
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View Funded ActivityDiscovery Early Career Researcher Award - Grant ID: DE180100743
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End Date: 01-2018
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View Funded ActivityDiscovery Projects - Grant ID: DP170103067
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