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Zhang J, Yang Q, Yue W, Yang B, Zhou W, Chen L, Huang X, Zhang W, Dong J, Ling J. Seagrass Thalassia hemprichii and associated bacteria co-response to the synergistic stress of ocean warming and ocean acidification. ENVIRONMENTAL RESEARCH 2023; 236:116658. [PMID: 37454799 DOI: 10.1016/j.envres.2023.116658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2023] [Revised: 06/07/2023] [Accepted: 07/11/2023] [Indexed: 07/18/2023]
Abstract
Seagrass meadows play vital ecological roles in the marine ecosystem. Global climate change poses considerable threats to seagrass survival. However, it is unclear how seagrass and its associated bacteria will respond under future complex climate change scenarios. This study explored the effects of ocean warming (+2 °C) and ocean acidification (-0.4 units) on seagrass physiological indexes and bacterial communities (sediment and rhizosphere bacteria) of the seagrass Thalassia hemprichii during an experimental exposure of 30 days. Results demonstrated that the synergistic effect of ocean warming and ocean acidification differed from that of one single factor on seagrass and the associated bacterial community. The seagrass showed a weak resistance to ocean warming and ocean acidification, which manifested through the increase in the activity of typical oxidoreductase enzymes. Moreover, the synergistic effect of ocean warming and ocean acidification caused a significant decrease in seagrass's chlorophyll content. Although the bacterial community diversity exhibited higher resistance to ocean warming and ocean acidification, further bacterial functional analysis revealed the synergistic effect of ocean warming and ocean acidification led to significant increases in SOX-related genes abundance which potentially supported the seagrass in resisting climate stress by producing sulfates and oxidizing hydrogen sulfide. More stable bacterial communities were detected in the seagrass rhizosphere under combined ocean warming and ocean acidification. While for one single environmental stress, simpler networks were detected in the rhizosphere. In addition, the observed significant correlations between several modules of the bacterial community and the physiological indexes of the seagrass indicate the possible intimate interaction between seagrass and bacteria under ocean warming and ocean acidification. This study extends our understanding regarding the role of seagrass associated bacterial communities and sheds light on both the prediction and preservation of the seagrass meadow ecosystems in response to global climate change.
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Affiliation(s)
- Jian Zhang
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, PR China; Key Laboratory of Tropical Marine Biotechnology of Hainan Province, Sanya Institute of Ocean Eco-Environmental Engineering, Sanya, 572000, PR China; Guangdong Provincial Observation and Research Station for Coastal Upwelling Ecosystem, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Shantou, 515041, PR China; Tropical Marine Biological Research Station in Hainan, Chinese Academy of Sciences, Sanya, 572000, PR China
| | - Qingsong Yang
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, PR China; Key Laboratory of Tropical Marine Biotechnology of Hainan Province, Sanya Institute of Ocean Eco-Environmental Engineering, Sanya, 572000, PR China; Guangdong Provincial Observation and Research Station for Coastal Upwelling Ecosystem, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Shantou, 515041, PR China; Tropical Marine Biological Research Station in Hainan, Chinese Academy of Sciences, Sanya, 572000, PR China
| | - Weizhong Yue
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, PR China; Tropical Marine Biological Research Station in Hainan, Chinese Academy of Sciences, Sanya, 572000, PR China
| | - Bing Yang
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, PR China; University of Chinese Academy of Sciences, Beijing, 100049, PR China
| | - Weiguo Zhou
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, PR China; Key Laboratory of Tropical Marine Biotechnology of Hainan Province, Sanya Institute of Ocean Eco-Environmental Engineering, Sanya, 572000, PR China; Guangdong Provincial Observation and Research Station for Coastal Upwelling Ecosystem, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Shantou, 515041, PR China; Tropical Marine Biological Research Station in Hainan, Chinese Academy of Sciences, Sanya, 572000, PR China
| | - Luxiang Chen
- College of Marine Sciences, South China Agricultural University, Guangzhou, Guangdong, 510642, PR China
| | - Xiaofang Huang
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, PR China; Key Laboratory of Tropical Marine Biotechnology of Hainan Province, Sanya Institute of Ocean Eco-Environmental Engineering, Sanya, 572000, PR China; Guangdong Provincial Observation and Research Station for Coastal Upwelling Ecosystem, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Shantou, 515041, PR China; University of Chinese Academy of Sciences, Beijing, 100049, PR China
| | - Wenqian Zhang
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, PR China; Key Laboratory of Tropical Marine Biotechnology of Hainan Province, Sanya Institute of Ocean Eco-Environmental Engineering, Sanya, 572000, PR China; Tropical Marine Biological Research Station in Hainan, Chinese Academy of Sciences, Sanya, 572000, PR China
| | - Junde Dong
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, PR China; Key Laboratory of Tropical Marine Biotechnology of Hainan Province, Sanya Institute of Ocean Eco-Environmental Engineering, Sanya, 572000, PR China; Guangdong Provincial Observation and Research Station for Coastal Upwelling Ecosystem, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Shantou, 515041, PR China; Tropical Marine Biological Research Station in Hainan, Chinese Academy of Sciences, Sanya, 572000, PR China.
| | - Juan Ling
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, PR China; Key Laboratory of Tropical Marine Biotechnology of Hainan Province, Sanya Institute of Ocean Eco-Environmental Engineering, Sanya, 572000, PR China; Guangdong Provincial Observation and Research Station for Coastal Upwelling Ecosystem, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Shantou, 515041, PR China; Tropical Marine Biological Research Station in Hainan, Chinese Academy of Sciences, Sanya, 572000, PR China.
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Celebi-Ergin B, Zimmerman RC, Hill VJ. Photorespiration in eelgrass ( Zostera marina L.): A photoprotection mechanism for survival in a CO 2-limited world. FRONTIERS IN PLANT SCIENCE 2022; 13:1025416. [PMID: 36438084 PMCID: PMC9692008 DOI: 10.3389/fpls.2022.1025416] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Accepted: 10/10/2022] [Indexed: 06/16/2023]
Abstract
Photorespiration, commonly viewed as a loss in photosynthetic productivity of C3 plants, is expected to decline with increasing atmospheric CO2, even though photorespiration plays an important role in the oxidative stress responses. This study aimed to quantify the role of photorespiration and alternative photoprotection mechanisms in Zostera marina L. (eelgrass), a carbon-limited marine C3 plant, in response to ocean acidification. Plants were grown in controlled outdoor aquaria at different [CO2]aq ranging from ~55 (ambient) to ~2121 μM for 13 months and compared for differences in leaf photochemistry by simultaneous measurements of O2 flux and variable fluorescence. At ambient [CO2], photosynthesis was carbon limited and the excess photon absorption was diverted both to photorespiration and non-photochemical quenching (NPQ). The dynamic range of NPQ regulation in ambient grown plants, in response to instantaneous changes in [CO2]aq, suggested considerable tolerance for fluctuating environmental conditions. However, 60 to 80% of maximum photosynthetic capacity of ambient plants was diverted to photorespiration resulting in limited carbon fixation. The photosynthesis to respiration ratio (P E : R D) of ambient grown plants increased 6-fold when measured under high CO2 because photorespiration was virtually suppressed. Plants acclimated to high CO2 maintained 4-fold higher P E : R D than ambient grown plants as a result of a 60% reduction in photorespiration. The O2 production efficiency per unit chlorophyll was not affected by the CO2 environment in which the plants were grown. Yet, CO2 enrichment decreased the light level to initiate NPQ activity and downregulated the biomass specific pigment content by 50% and area specific pigment content by 30%. Thus, phenotypic acclimation to ocean carbonation in eelgrass, indicating the coupling between the regulation of photosynthetic structure and metabolic carbon demands, involved the downregulation of light harvesting by the photosynthetic apparatus, a reduction in the role of photorespiration and an increase in the role of NPQ in photoprotection. The quasi-mechanistic model developed in this study permits integration of photosynthetic and morphological acclimation to ocean carbonation into seagrass productivity models, by adjusting the limits of the photosynthetic parameters based on substrate availability and physiological capacity.
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Assessing the Effects of Ocean Warming and Acidification on the Seagrass Thalassia hemprichii. JOURNAL OF MARINE SCIENCE AND ENGINEERING 2022. [DOI: 10.3390/jmse10060714] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Seagrass beds serve as important carbon sinks, and it is thought that increasing the quantity and quality of such sinks could help to slow the rate of global climate change. Therefore, it will be important to (1) gain a better understanding of seagrass bed metabolism and (2) document how these high-productivity ecosystems are impacted by climate change-associated factors, such as ocean acidification (OA) and ocean warming (OW). A mesocosm-based approach was taken herein in which a tropical, Western Pacific seagrass species Thalassia hemprichii was cultured under either control or OA-simulating conditions; the temperature was gradually increased from 25 to 31 °C for both CO2 enrichment treatments, and it was hypothesized that this species would respond positively to OA and elevated temperature. After 12 weeks of exposure, OA (~1200 ppm) led to (1) increases in underground biomass and root C:N ratios and (2) decreases in root nitrogen content. Rising temperatures (25 to 31 °C) increased the maximum quantum yield of photosystem II (Fv:Fm), productivity, leaf growth rate, decomposition rate, and carbon sequestration, but decreased the rate of shoot density increase and the carbon content of the leaves; this indicates that warming alone does not increase the short-term carbon sink capacity of this seagrass species. Under high CO2 and the highest temperature employed (31 °C), this seagrass demonstrated its highest productivity, Fv:Fm, leaf growth rate, and carbon sequestration. Collectively, then, it appears that high CO2 levels offset the negative effects of high temperature on this seagrass species. Whether this pattern is maintained at temperatures that actually induce marked seagrass stress (likely beginning at 33–34 °C in Southern Taiwan) should be the focus of future research.
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Kaldy JE, Brown CA, Pacella SR. Carbon limitation in response to nutrient loading in an eelgrass mesocosm: influence of water residence time. MARINE ECOLOGY PROGRESS SERIES 2022; 689:1-17. [PMID: 35938055 PMCID: PMC9347230 DOI: 10.3354/meps14061] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Altered primary productivity associated with eutrophication impacts not only ecosystem structure but also the biogeochemical cycling of oxygen and carbon. We conducted laboratory experiments to empirically determine how residence time (1, 3, 10 d) influences eutrophication responses in a simplified Pacific Northwest Zostera marina-green macroalgal community. We expected long-residence time (RT) systems to exhibit eutrophication impairments. Instead, we observed an accumulation of nutrients at all RTs and a shift in the dissolved inorganic carbon speciation away from CO2 (aq) with unexpected consequences for eel grass plant condition, including shoot mortality. Most metrics responded more strongly to temperature treatments than to RT treatments. No dramatic shifts in the relative abundance of Z. marina and green macro algae were detected. Z. marina shoot density proliferated in cool temperatures (12°C) with a modest decline at 20°C. Eelgrass loss was associated with high total scale pH (pHT) and CO2 (aq) concentrations of <10 μmol kg-1 CO2 (aq), but not with high nutrients. Z. marina δ13C values support the hypo thesis that carbon availability was greater at short RT. Further, very low leaf sugar concentrations are consistent with extreme photosynthetic CO2 (aq) limitation. We suggest that the effects of extremely low environ mental car bon concentrations (CO2 (aq)) and increased respiration at warm temperatures (20°C) and other physiological processes can lead to internal carbon limitation and shoot mortality. Eutrophication responses to nutrient loading are more nuanced than just light limitation of eelgrass and require additional research on the interaction of the biogeochemical environment and plant physiology to better understand estuarine ecosystem disruption.
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Berg P, Huettel M, Glud RN, Reimers CE, Attard KM. Aquatic Eddy Covariance: The Method and Its Contributions to Defining Oxygen and Carbon Fluxes in Marine Environments. ANNUAL REVIEW OF MARINE SCIENCE 2022; 14:431-455. [PMID: 34587456 DOI: 10.1146/annurev-marine-042121-012329] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Aquatic eddy covariance (AEC) is increasingly being used to study benthic oxygen (O2) flux dynamics, organic carbon cycling, and ecosystem health in marine and freshwater environments. Because it is a noninvasive technique, has a high temporal resolution (∼15 min), and integrates over a large area of the seafloor (typically 10-100 m2), it has provided new insights on the functioning of aquatic ecosystems under naturally varying in situ conditions and has given us more accurate assessments of their metabolism. In this review, we summarize biogeochemical, ecological, and biological insightsgained from AEC studies of marine ecosystems. A general finding for all substrates is that benthic O2 exchange is far more dynamic than earlier recognized, and thus accurate mean values can only be obtained from measurements that integrate over all timescales that affect the local O2 exchange. Finally, we highlight new developments of the technique, including measurements of air-water gas exchange and long-term deployments.
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Affiliation(s)
- Peter Berg
- Department of Environmental Sciences, University of Virginia, Charlottesville, Virginia 22908, USA;
| | - Markus Huettel
- Department of Earth, Ocean, and Atmospheric Science, Florida State University, Tallahassee, Florida 32306, USA;
| | - Ronnie N Glud
- Danish Center for Hadal Research (HADAL), Nordic Center for Earth Evolution (NordCEE), Danish Institute for Advanced Study (DIAS), and Department of Biology, University of Southern Denmark, DK-5230 Odense M, Denmark; ,
- Department of Ocean and Environmental Sciences, Tokyo University of Marine Science and Technology, Tokyo 108-8477, Japan
| | - Clare E Reimers
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97331, USA;
| | - Karl M Attard
- Danish Center for Hadal Research (HADAL), Nordic Center for Earth Evolution (NordCEE), Danish Institute for Advanced Study (DIAS), and Department of Biology, University of Southern Denmark, DK-5230 Odense M, Denmark; ,
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Björk M, Asplund ME, Deyanova D, Gullström M. The amount of light reaching the leaves in seagrass (Zostera marina) meadows. PLoS One 2021; 16:e0257586. [PMID: 34547042 PMCID: PMC8454950 DOI: 10.1371/journal.pone.0257586] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Accepted: 09/03/2021] [Indexed: 12/04/2022] Open
Abstract
Seagrass meadows, and other submerged vegetated habitats, support a wide range of essential ecological services, but the true extents of these services are in many ways still not quantified. One important tool needed to assess and model many of these services is accurate estimations of the systems´ primary productivity. Such productivity estimations require an understanding of the underwater light field, especially regarding the amount of light that actually reaches the plants' photosynthetic tissue. In this study, we tested a simple practical approach to estimate leaf light exposure, relative to incoming light at the canopy, by attaching light sensitive film at different positions on leaves of Zostera marina, eelgrass, in four seagrass meadows composed of different shoot density and at two different depths. We found that the light reaching the leaves decreased linearly down through the canopy. While the upper parts of the leaves received approximately the same level of light (photosynthetic photon flux density, PPFD) as recorded with a PAR meter at the canopy top, the average light that the seagrass leaves were exposed to varied between 40 and 60% of the light on top of the canopy, with an overall average of 48%. We recommend that actual light interception is measured when assessing or modelling light depending processes in submerged vegetation, but if this is not achievable a rough estimation for vegetation similar to Z. marina would be to use a correction factor of 0.5 to compensate for the reduced light due to leaf orientation and internal shading.
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Affiliation(s)
- Mats Björk
- Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden
| | - Maria E. Asplund
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Kristineberg, Fiskebäckskil, Sweden
| | - Diana Deyanova
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Kristineberg, Fiskebäckskil, Sweden
| | - Martin Gullström
- School of Natural Sciences, Technology and Environmental Studies, Södertörn University, Huddinge, Sweden
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Sensitivity of Photosynthesis to Warming in Two Similar Species of the Aquatic Angiosperm Ruppia from Tropical and Temperate Habitats. SUSTAINABILITY 2021. [DOI: 10.3390/su13169433] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Climate change-related events, such as marine heatwaves, are increasing seawater temperatures, thereby putting pressure on marine biota. The cosmopolitan distribution and significant contribution to marine primary production by the genus Ruppia makes them interesting organisms to study thermal tolerance and local adaptation. In this study, we investigated the photosynthetic responses in Ruppia to the predicted future warming in two contrasting bioregions, temperate Sweden and tropical Thailand. Through DNA barcoding, specimens were determined to Ruppia cirrhosa for Sweden and Ruppia maritima for Thailand. Photosynthetic responses were assessed using pulse amplitude-modulated fluorometry, firstly in short time incubations at 18, 23, 28, and 33 °C in the Swedish set-up and 28, 33, 38, and 43 °C in the Thai set-up. Subsequent experiments were conducted to compare the short time effects to longer, five-day incubations in 28 °C for Swedish plants and 40 °C for Thai plants. Swedish R. cirrhosa displayed minor response, while Thai R. maritima was more sensitive to both direct and prolonged temperature stress with a drastic decrease in the photosynthetic parameters leading to mortality. The results indicate that in predicted warming scenarios, Swedish R. cirrhosa may sustain an efficient photosynthesis and potentially outcompete more heat-sensitive species. However, populations of the similar R. maritima in tropical environments may suffer a decline as their productivity will be highly reduced.
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Miller CA, Kelley AL. Alkalinity cycling and carbonate chemistry decoupling in seagrass mystify processes of acidification mitigation. Sci Rep 2021; 11:13500. [PMID: 34188095 PMCID: PMC8241997 DOI: 10.1038/s41598-021-92771-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 06/16/2021] [Indexed: 11/18/2022] Open
Abstract
The adverse conditions of acidification on sensitive marine organisms have led to the investigation of bioremediation methods as a way to abate local acidification. This phytoremediation, by macrophytes, is expected to reduce the severity of acidification in nearshore habitats on short timescales. Characterizing the efficacy of phytoremediation can be challenging as residence time, tidal mixing, freshwater input, and a limited capacity to fully constrain the carbonate system can lead to erroneous conclusions. Here, we present in situ observations of carbonate chemistry relationships to seagrass habitats by comparing dense (DG), patchy (PG), and no grass (NG) Zostera marina pools in the high intertidal experiencing intermittent flooding. High-frequency measurements of pH, alkalinity (TA), and total-CO2 elucidate extreme diel cyclicity in all parameters. The DG pool displayed frequent decoupling between pH and aragonite saturation state (Ωarg) suggesting pH-based inferences of acidification remediation by seagrass can be misinterpreted as pH and Ωarg can be independent stressors for some bivalves. Estimates show the DG pool had an integrated ΔTA of 550 μmol kg−1 over a 12 h period, which is ~ 60% > the PG and NG pools. We conclude habitats with mixed photosynthesizers (i.e., PG pool) result in less decoupling between pH and Ωarg.
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Affiliation(s)
- Cale A Miller
- Department of Evolution and Ecology, University of California Davis, Davis, CA, 95616, USA. .,College of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Fairbanks, AK, 99775, USA.
| | - Amanda L Kelley
- College of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Fairbanks, AK, 99775, USA
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Zhang X, Zhou Y, Adams MP, Wang F, Xu S, Wang P, Liu P, Liu X, Yue S. Plant morphology and seed germination responses of seagrass (Zostera japonica) to water depth and light availability in Ailian Bay, northern China. MARINE ENVIRONMENTAL RESEARCH 2020; 162:105082. [PMID: 32836011 DOI: 10.1016/j.marenvres.2020.105082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 06/12/2020] [Accepted: 07/13/2020] [Indexed: 06/11/2023]
Abstract
Poor water quality and light reduction owing to anthropogenic impacts are the most widespread causes behind marine submerged angiosperm (seagrass) declines, worldwide. Seagrasses could respond to sustained environmental stresses, such as increasing water depth and light reduction, through morphological changes, particularly shoot density and/or biomass reductions. The seagrass Zostera japonica Asch. and Graebn. has been introduced to the Pacific Coast of North America, but it is widely threatened in its native northwestern Pacific Coast range alongside the east coast of China. The main aims of this study were to determine: 1) the depth limit of Z. japonica growth in its native range, and 2) how light availability affects the growth and recruitment of Z. japonica. To achieve these aims, we investigated the temporal responses of Z. japonica shoots and seeds from an intertidal donor site, Swan Lake, to light availability at water depths ranging from 1 to 6 m using in situ suspended cultures deployed in the experimental site, Ailian Bay, off the coast of Weihai City, China. The results showed that the transplanted Z. japonica shoots and seeds could survive for the duration of their annual growth cycle, permanently underwater, at a depth ≤2 m. There was a significant inverse relationship between water depth and time to complete shoot loss, despite temporally varying water clarity levels. Due to the local turbidity of the waters in Ailian Bay, a depth of 2 m yielded sufficient light deprivation (5%-37% surface irradiance) to negatively affect the seagrass shoot density. Our results suggest that this intertidal species can potentially persist in shallow subtidal areas following transplantation with shoots and seeds. The findings may also serve as useful information for local seagrass distribution limits, and will facilitate their habitat establishment and restoration efforts.
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Affiliation(s)
- Xiaomei Zhang
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China; CAS Engineering Laboratory for Marine Ranching, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China.
| | - Yi Zhou
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China; CAS Engineering Laboratory for Marine Ranching, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China.
| | - Matthew P Adams
- School of Mathematical Sciences, Queensland University of Technology, Brisbane, 4000, Queensland, Australia; School of Chemical Engineering, The University of Queensland, St Lucia, 4072, Queensland, Australia.
| | - Feng Wang
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Shaochun Xu
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Pengmei Wang
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Peng Liu
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xujia Liu
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Shidong Yue
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; University of Chinese Academy of Sciences, Beijing, 100049, China
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Kalokora OJ, Buriyo AS, Asplund ME, Gullström M, Mtolera MSP, Björk M. An experimental assessment of algal calcification as a potential source of atmospheric CO2. PLoS One 2020; 15:e0231971. [PMID: 32348324 PMCID: PMC7190104 DOI: 10.1371/journal.pone.0231971] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 04/03/2020] [Indexed: 11/19/2022] Open
Abstract
Marine vegetated ecosystems such as seagrass meadows are increasingly acknowledged as important carbon sinks based on their ability to capture and store atmospheric carbon dioxide, thereby contributing to climate change mitigation. Most studies on carbon storage in marine ecosystems have focused on organic carbon, leaving inorganic carbon processes such as calcification unaccounted for, despite of their critical role in the global carbon budget. This is probably because of uncertainties regarding the role of calcification in marine carbon budgets as either atmospheric CO2 source or sink. Here, we conducted a laboratory experiment to investigate the influence of a calcifying alga (Corallina officinalis L.) on seawater carbon content, using a non-calcifying alga (Ulva lactuca L.) as a control. In a first part, algae were incubated separately while measuring changes in seawater pH, total alkalinity (TA) and total dissolved inorganic carbon (DIC). The amount of carbon used in photosynthetic uptake and production of CaCO3 was then calculated. In a second, directly following, part the algae were removed and DIC levels were allowed to equilibrate with air until the pH stabilized and the loss of CO2 to air was calculated as the difference in total DIC from the start of part one, to the end of the second part. The results showed that C. officinalis caused a significant and persistent reduction in total dissolved inorganic carbon (DIC), TA and seawater pH, while no such permanent changes were caused by U. lactuca. These findings indicate that calcification can release a significant amount of CO2 to the atmosphere and thereby possibly counteract the carbon sequestration in marine vegetated ecosystems if this CO2 is not re-fixed in the system. Our research emphasises the importance of considering algal calcification in future assessments on carbon storage in coastal areas.
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Affiliation(s)
- Olivia J. Kalokora
- Dar es Salaam University College of Education (DUCE), Dar es Salaam, Tanzania
- Department of Botany, University of Dar es Salaam, Dar es Salaam, Tanzania
| | - Amelia S. Buriyo
- Department of Botany, University of Dar es Salaam, Dar es Salaam, Tanzania
| | - Maria E. Asplund
- Department of Marine Sciences, University of Gothenburg, Kristineberg, Fiskebäckskil, Sweden
| | - Martin Gullström
- Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden
- Department of Biological and Environmental Sciences, University of Gothenburg, Kristineberg, Fiskebäckskil, Sweden
| | | | - Mats Björk
- Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden
- * E-mail:
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Perry D, Hammar L, Linderholm HW, Gullström M. Spatial risk assessment of global change impacts on Swedish seagrass ecosystems. PLoS One 2020; 15:e0225318. [PMID: 31978099 PMCID: PMC6980605 DOI: 10.1371/journal.pone.0225318] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 11/01/2019] [Indexed: 11/19/2022] Open
Abstract
Improved knowledge on the risk in ecologically important habitats on a regional scale from multiple stressors is critical for managing functioning and resilient ecosystems. This risk assessment aimed to identify seagrass ecosystems in southern Sweden that will be exposed to a high degree of change from multiple global change stressors in mid- and end-of-century climate change conditions. Risk scores were calculated from the expected overlap of three stressors: sea surface temperature increases, ocean acidification and wind driven turbid conditions. Three high-risk regions were identified as areas likely to be exposed to a particularly high level of pressure from the global stressors by the end of the century. In these areas it can be expected that there will be a large degree of stressor change from the current conditions. Given the ecological importance of seagrass meadows for maintaining high biodiversity and a range of other ecosystem services, these risk zones should be given high priority for incorporation into management strategies, which can attempt to reduce controllable stressors in order to mitigate the consequences of some of the impending pressures and manage for maintained ecosystem resilience.
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Affiliation(s)
- Diana Perry
- Seagrass Ecology and Physiology Research Group, Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden
- Department of Aquatic Resources, Swedish University of Agricultural Sciences, Lysekil, Sweden
- * E-mail:
| | - Linus Hammar
- Octopus Ink Research & Analysis, Gothenburg, Sweden
| | - Hans W. Linderholm
- Regional Climate Group, Department of Earth Sciences, University of Gothenburg, Gothenburg, Sweden
| | - Martin Gullström
- Seagrass Ecology and Physiology Research Group, Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden
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12
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Viana IG, Moreira-Saporiti A, Teichberg M. Species-Specific Trait Responses of Three Tropical Seagrasses to Multiple Stressors: The Case of Increasing Temperature and Nutrient Enrichment. FRONTIERS IN PLANT SCIENCE 2020; 11:571363. [PMID: 33224162 PMCID: PMC7674176 DOI: 10.3389/fpls.2020.571363] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 10/12/2020] [Indexed: 05/05/2023]
Abstract
Seagrass meadows are declining globally. The decrease of seagrass area is influenced by the simultaneous occurrence of many factors at the local and global scale, including nutrient enrichment and climate change. This study aims to find out how increasing temperature and nutrient enrichment affect the morphological, biochemical and physiological responses of three coexisting tropical species, Thalassia hemprichii, Cymodocea serrulata and Halophila stipulacea. To achieve these aims, a 1-month experiment under laboratory conditions combining two temperature (maximum ambient temperature and current average temperature) and two nutrient (high and low N and P concentrations) treatments was conducted. The results showed that the seagrasses were differentially affected by all treatments depending on their life-history strategies. Under higher temperature treatments, C. serrulata showed photo-acclimation strategies, while T. hemprichii showed decreased photo-physiological performance. In contrast, T. hemprichii was resistant to nutrient over-enrichment, showing enhanced nutrient content and physiological changes, but C. serrulata suffered BG nutrient loss. The limited response of H. stipulacea to nutrient enrichment or high temperature suggests that this seagrass is a tolerant species that may have a dormancy state with lower photosynthetic performance and smaller-size individuals. Interaction between both factors was limited and generally showed antagonistic effects only on morphological and biochemical traits, but not on physiological traits. These results highlight the different effects and strategies co-inhabiting seagrasses have in response to environmental changes, showing winners and losers of a climate change scenario that may eventually cause biodiversity loss. Trait responses to these stressors could potentially make the seagrasses weaker to cope with following events, due to BG biomass or nutrient loss. This is of importance as biodiversity loss in tropical seagrass ecosystems could change the overall effectiveness of ecosystem functions and services provided by the seagrass meadows.
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Affiliation(s)
- Inés G. Viana
- Department of Ecology and Animal Biology, University of Vigo, Vigo, Spain
- Leibniz Centre for Tropical Marine Research GmbH, Bremen, Germany
- *Correspondence: Inés G. Viana, ;
| | - Agustín Moreira-Saporiti
- Leibniz Centre for Tropical Marine Research GmbH, Bremen, Germany
- Faculty of Biology and Chemistry, University of Bremen, Bremen, Germany
| | - Mirta Teichberg
- Leibniz Centre for Tropical Marine Research GmbH, Bremen, Germany
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Purification and characterization of thymol blue for spectrophotometric pH measurements in rivers, estuaries, and oceans. Anal Chim Acta 2019; 1090:91-99. [PMID: 31655650 DOI: 10.1016/j.aca.2019.09.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 08/31/2019] [Accepted: 09/03/2019] [Indexed: 11/22/2022]
Abstract
Thymol blue (TB) is one of a suite of indicator dyes appropriate for spectrophotometric determinations of the pH of aqueous solutions. For measurements of seawater pH, meta-cresol purple (mCP) is most often used, but TB is especially well suited for measurements in surface or shallow waters where the pH may exceed the optimal indicating range of mCP (e.g., due to photosynthesis). This work presents flash chromatography procedures for purifying commercially available TB and describes physical-chemical characteristics of the purified dye, thus enabling the acquisition of spectrophotometric pH measurements over a wide range of practical salinities (SP) and temperatures (T). The essential TB characteristics for 0 ≤ SP ≤ 40 and 278.15 ≤ T ≤ 308.15 K are described by: pHT=-TB(log(K2Te2))+log((R-e1)/(1-Re4)) TB(logK2Te2)=6.6942-0.001129Sp0.5T-0.5926T-0.5Sp+619.40/T+0.1441SP-0.02591Sp1.5+0.0034Sp2-0.0001754Sp2.5 e1 = -0.00132 + 0.00001600T e4 = -0.005042 + 0.0002094T + 0.01916SP0.5/T where pHT is pH determined on the total hydrogen ion concentration scale; R is the ratio of TB absorbances (A) at 435 and 596 nm (596A/435A); K2T is the equilibrium constant for the second TB dissociation step on the total scale; and e1, e2, and e4 are TB molar absorptivity ratios. This characterization was developed in a manner that ensures consistency with the primary TRIS buffer standards used in previously published characterizations of mCP. With this characterization, TB joins mCP as a sulfonephthalein indicator that has been characterized over the ranges of salinity and temperature required to make high-quality pH measurements in rivers, estuaries, and the open ocean. The full characterization of purified TB reported here extends the upper range of pHT that can be accessed with precise spectrophotometric measurements by approximately 0.50 pH units.
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14
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Kim M, Pernice M, Watson-Lazowski A, Guagliardo P, Kilburn MR, Larkum AWD, Raven JA, Ralph PJ. Effect of reduced irradiance on 13C uptake, gene expression and protein activity of the seagrass Zostera muelleri. MARINE ENVIRONMENTAL RESEARCH 2019; 149:80-89. [PMID: 31181418 DOI: 10.1016/j.marenvres.2019.06.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 05/30/2019] [Accepted: 06/05/2019] [Indexed: 06/09/2023]
Abstract
Photosynthesis in the seagrass Zostera muelleri remains poorly understood. We investigated the effect of reduced irradiance on the incorporation of 13C, gene expression of photosynthetic, photorespiratory and intermediates recycling genes as well as the enzymatic content and activity of Rubisco and PEPC within Z. muelleri. Following 48 h of reduced irradiance, we found that i) there was a ∼7 fold reduction in 13C incorporation in above ground tissue, ii) a significant down regulation of photosynthetic, photorespiratory and intermediates recycling genes and iii) no significant difference in enzyme activity and content. We propose that Z. muelleri is able to alter its physiology in order to reduce the amount of C lost through photorespiration to compensate for the reduced carbon assimilation as a result of reduced irradiance. In addition, the first estimated rate constant (Kcat) and maximum rates of carboxylation (Vcmax) of Rubisco is reported for the first time for Z. muelleri.
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Affiliation(s)
- Mikael Kim
- University of Technology Sydney, Climate Change Cluster, Ultimo, NSW, 2007, Australia
| | - Mathieu Pernice
- University of Technology Sydney, Climate Change Cluster, Ultimo, NSW, 2007, Australia.
| | - Alexander Watson-Lazowski
- Hawkesbury Institute for the Environment, University of Western Sydney, Penrith, Australia; ARC Centre of Excellence for Translational Photosynthesis, Australian National University, Canberra, Australia
| | - Paul Guagliardo
- Centre for Microscopy, Characterisation and Analysis, University of Western Australia, Perth, WA, Australia
| | - Matt R Kilburn
- Centre for Microscopy, Characterisation and Analysis, University of Western Australia, Perth, WA, Australia
| | - Anthony W D Larkum
- University of Technology Sydney, Climate Change Cluster, Ultimo, NSW, 2007, Australia
| | - John A Raven
- University of Technology Sydney, Climate Change Cluster, Ultimo, NSW, 2007, Australia; Division of Plant Science, University of Dundee at the James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK
| | - Peter J Ralph
- University of Technology Sydney, Climate Change Cluster, Ultimo, NSW, 2007, Australia
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15
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Egea LG, Jiménez–Ramos R, Hernández I, Brun FG. Effect of In Situ short-term temperature increase on carbon metabolism and dissolved organic carbon (DOC) fluxes in a community dominated by the seagrass Cymodocea nodosa. PLoS One 2019; 14:e0210386. [PMID: 30640926 PMCID: PMC6331083 DOI: 10.1371/journal.pone.0210386] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 12/21/2018] [Indexed: 02/07/2023] Open
Abstract
Seagrasses form one of the most productive and threatened ecosystems worldwide because of global change and anthropogenic pressures. The frequency of extreme climatic events, such as heat waves, are expected to increase and may drive even more adverse effects than gradual warming. This study explores for the first time the effects of a sudden and temporary increase of temperature in situ on carbon metabolism and dissolved organic carbon (DOC) fluxes in a community dominated by a seagrass (Cymodocea nodosa) during two contrasting seasons (winter and summer). Results showed a positive correlation between temperature and seagrass production between seasons, while the experimental sudden and temporary increase in water temperature did not produce significant differences in carbon community metabolism and DOC fluxes in winter. In contrast, high temperature conditions in summer enhanced significantly the net community production and affected positively to DOC fluxes. Hence, this study indicates that a sudden and temporary increase in water temperature, which characterize marine heat waves, in temperate areas may enhance the autotrophic metabolism of seagrass communities and can yield an increase in the DOC released, in contrast to previous researches suggesting solely negative effects on seagrasses.
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Affiliation(s)
- Luis G. Egea
- Department of Biology, Faculty of Marine and Environmental Sciences, University of Cadiz, Puerto Real (Cádiz), Spain
- * E-mail:
| | - Rocío Jiménez–Ramos
- Department of Biology, Faculty of Marine and Environmental Sciences, University of Cadiz, Puerto Real (Cádiz), Spain
| | - Ignacio Hernández
- Department of Biology, Faculty of Marine and Environmental Sciences, University of Cadiz, Puerto Real (Cádiz), Spain
| | - Fernando G. Brun
- Department of Biology, Faculty of Marine and Environmental Sciences, University of Cadiz, Puerto Real (Cádiz), Spain
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Collier CJ, Langlois L, Ow Y, Johansson C, Giammusso M, Adams MP, O'Brien KR, Uthicke S. Losing a winner: thermal stress and local pressures outweigh the positive effects of ocean acidification for tropical seagrasses. THE NEW PHYTOLOGIST 2018; 219:1005-1017. [PMID: 29855044 DOI: 10.1111/nph.15234] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Accepted: 04/20/2018] [Indexed: 05/21/2023]
Abstract
Seagrasses are globally important coastal habitat-forming species, yet it is unknown how seagrasses respond to the combined pressures of ocean acidification and warming of sea surface temperature. We exposed three tropical species of seagrass (Cymodocea serrulata, Halodule uninervis, and Zostera muelleri) to increasing temperature (21, 25, 30, and 35°C) and pCO2 (401, 1014, and 1949 μatm) for 7 wk in mesocosms using a controlled factorial design. Shoot density and leaf extension rates were recorded, and plant productivity and respiration were measured at increasing light levels (photosynthesis-irradiance curves) using oxygen optodes. Shoot density, growth, photosynthetic rates, and plant-scale net productivity occurred at 25°C or 30°C under saturating light levels. High pCO2 enhanced maximum net productivity for Z. muelleri, but not in other species. Z. muelleri was the most thermally tolerant as it maintained positive net production to 35°C, yet for the other species there was a sharp decline in productivity, growth, and shoot density at 35°C, which was exacerbated by pCO2 . These results suggest that thermal stress will not be offset by ocean acidification during future extreme heat events and challenges the current hypothesis that tropical seagrass will be a 'winner' under future climate change conditions.
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Affiliation(s)
- Catherine J Collier
- Centre for Tropical Water & Aquatic Ecosystem Research (TropWATER), James Cook University, Cairns, Qld, 4870, Australia
| | - Lucas Langlois
- Centre for Tropical Water & Aquatic Ecosystem Research (TropWATER), James Cook University, Cairns, Qld, 4870, Australia
| | - Yan Ow
- School of Marine and Tropical Biology, James Cook University, Townsville, Qld, 4811, Australia
- Australian Institute of Marine Science, PMB No. 3, Townsville, 4810, Qld, Australia
- Experimental Marine Ecology Laboratory, Department of Biological Sciences, National University of Singapore, Singapore, 117557, Singapore
| | - Charlotte Johansson
- Australian Institute of Marine Science, PMB No. 3, Townsville, 4810, Qld, Australia
| | - Manuela Giammusso
- Australian Institute of Marine Science, PMB No. 3, Townsville, 4810, Qld, Australia
| | - Matthew P Adams
- School of Chemical Engineering, The University of Queensland, Brisbane, 4072, Qld, Australia
| | - Katherine R O'Brien
- School of Chemical Engineering, The University of Queensland, Brisbane, 4072, Qld, Australia
| | - Sven Uthicke
- Australian Institute of Marine Science, PMB No. 3, Townsville, 4810, Qld, Australia
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17
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Kim M, Brodersen KE, Szabó M, Larkum AWD, Raven JA, Ralph PJ, Pernice M. Low oxygen affects photophysiology and the level of expression of two-carbon metabolism genes in the seagrass Zostera muelleri. PHOTOSYNTHESIS RESEARCH 2018; 136:147-160. [PMID: 0 DOI: 10.1007/s11120-017-0452-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Accepted: 09/27/2017] [Indexed: 05/03/2023]
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18
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George R, Gullström M, Mangora MM, Mtolera MSP, Björk M. High midday temperature stress has stronger effects on biomass than on photosynthesis: A mesocosm experiment on four tropical seagrass species. Ecol Evol 2018; 8:4508-4517. [PMID: 29760891 PMCID: PMC5938440 DOI: 10.1002/ece3.3952] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 01/19/2018] [Accepted: 01/27/2018] [Indexed: 11/24/2022] Open
Abstract
The effect of repeated midday temperature stress on the photosynthetic performance and biomass production of seagrass was studied in a mesocosm setup with four common tropical species, including Thalassia hemprichii, Cymodocea serrulata, Enhalus acoroides, and Thalassodendron ciliatum. To mimic natural conditions during low tides, the plants were exposed to temperature spikes of different maximal temperatures, that is, ambient (29–33°C), 34, 36, 40, and 45°C, during three midday hours for seven consecutive days. At temperatures of up to 36°C, all species could maintain full photosynthetic rates (measured as the electron transport rate, ETR) throughout the experiment without displaying any obvious photosynthetic stress responses (measured as declining maximal quantum yield, Fv/Fm). All species except T. ciliatum could also withstand 40°C, and only at 45°C did all species display significantly lower photosynthetic rates and declining Fv/Fm. Biomass estimation, however, revealed a different pattern, where significant losses of both above‐ and belowground seagrass biomass occurred in all species at both 40 and 45°C (except for C. serrulata in the 40°C treatment). Biomass losses were clearly higher in the shoots than in the belowground root–rhizome complex. The findings indicate that, although tropical seagrasses presently can cope with high midday temperature stress, a few degrees increase in maximum daily temperature could cause significant losses in seagrass biomass and productivity.
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Affiliation(s)
- Rushingisha George
- Seagrass Ecology and Physiology Research Group Department of Ecology, Environment and Plant Sciences Stockholm University Stockholm Sweden.,Tanzania Fisheries Research Institute (TAFIRI) Dar es Salaam Tanzania
| | - Martin Gullström
- Seagrass Ecology and Physiology Research Group Department of Ecology, Environment and Plant Sciences Stockholm University Stockholm Sweden
| | | | | | - Mats Björk
- Seagrass Ecology and Physiology Research Group Department of Ecology, Environment and Plant Sciences Stockholm University Stockholm Sweden
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19
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Gullström M, Lyimo LD, Dahl M, Samuelsson GS, Eggertsen M, Anderberg E, Rasmusson LM, Linderholm HW, Knudby A, Bandeira S, Nordlund LM, Björk M. Blue Carbon Storage in Tropical Seagrass Meadows Relates to Carbonate Stock Dynamics, Plant–Sediment Processes, and Landscape Context: Insights from the Western Indian Ocean. Ecosystems 2017. [DOI: 10.1007/s10021-017-0170-8] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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20
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Larkum AWD, Davey PA, Kuo J, Ralph PJ, Raven JA. Carbon-concentrating mechanisms in seagrasses. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:3773-3784. [PMID: 28911056 DOI: 10.1093/jxb/erx206] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Seagrasses are unique angiosperms that carry out growth and reproduction submerged in seawater. They occur in at least three families of the Alismatales. All have chloroplasts mainly in the cells of the epidermis. Living in seawater, the supply of inorganic carbon (Ci) to the chloroplasts is diffusion limited, especially under unstirred conditions. Therefore, the supply of CO2 and bicarbonate across the diffusive boundary layer on the outer side of the epidermis is often a limiting factor. Here we discuss the evidence for mechanisms that enhance the uptake of Ci into the epidermal cells. Since bicarbonate is plentiful in seawater, a bicarbonate pump might be expected; however, the evidence for such a pump is not strongly supported. There is evidence for a carbonic anhydrase outside the outer plasmalemma. This, together with evidence for an outward proton pump, suggests the possibility that local acidification leads to enhanced concentrations of CO2 adjacent to the outer tangential epidermal walls, which enhances the uptake of CO2, and this could be followed by a carbon-concentrating mechanism (CCM) in the cytoplasm and/or chloroplasts. The lines of evidence for such an epidermal CCM are discussed, including evidence for special 'transfer cells' in some but not all seagrass leaves in the tangential inner walls of the epidermal cells. It is concluded that seagrasses have a CCM but that the case for concentration of CO2 at the site of Rubisco carboxylation is not proven.
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Affiliation(s)
- Anthony William D Larkum
- Plant Functional Biology and Global Climate Change Cluster, University of Technology Sydney, NSW 2009, Australia
| | - Peter A Davey
- Plant Functional Biology and Global Climate Change Cluster, University of Technology Sydney, NSW 2009, Australia
| | - John Kuo
- Electron Microscope Centre, University of Western Australia, WA 6900, Australia
| | - Peter J Ralph
- Plant Functional Biology and Global Climate Change Cluster, University of Technology Sydney, NSW 2009, Australia
| | - John A Raven
- Plant Functional Biology and Global Climate Change Cluster, University of Technology Sydney, NSW 2009, Australia
- University of Dundee at JHI, Invergowrie, Dundee, UK
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21
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Rasmusson LM, Lauritano C, Procaccini G, Gullström M, Buapet P, Björk M. Respiratory oxygen consumption in the seagrass Zostera marina varies on a diel basis and is partly affected by light. MARINE BIOLOGY 2017; 164:140. [PMID: 28596620 PMCID: PMC5446554 DOI: 10.1007/s00227-017-3168-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Accepted: 05/17/2017] [Indexed: 06/07/2023]
Abstract
The seagrass Zostera marina is an important marine ecosystem engineer, greatly influencing oxygen and carbon fluctuations in temperate coastal areas. Although photosynthetically driven gas fluxes are well studied, the impact of the plant's mitochondrial respiration on overall CO2 and O2 fluxes in marine vegetated areas is not yet understood. Likewise, the gene expression in relation to the respiratory pathway has not been well analyzed in seagrasses. This study uses a combined approach, studying respiratory oxygen consumption rates in darkness simultaneously with changes in gene expression, with the aim of examining how respiratory oxygen consumption fluctuates on a diel basis. Measurements were first made in a field study where samples were taken directly from the ocean to the laboratory for estimations of respiratory rates. This was followed by a laboratory study where measurements of respiration and expression of genes known to be involved in mitochondrial respiration were conducted for 5 days under light conditions mimicking natural summer light (i.e., 15 h of light and 9 h of darkness), followed by 3 days of constant darkness to detect the presence of a potential circadian clock. In the field study, there was a clear diel variation in respiratory oxygen consumption with the highest rates in the late evening and at night (0.766 and 0.869 µmol O2 m-2 s-1, respectively). These repetitive diel patterns were not seen in the laboratory, where water conditions (temperature, pH, and oxygen) showed minor fluctuations and only light varied. The gene expression analysis did not give clear evidence on drivers behind the respiratory fluxes; however, expression levels of the selected genes generally increased when the seagrass was kept in constant darkness. While light may influence mitochondrial respiratory fluxes, it appears that other environmental factors (e.g., temperature, pH, or oxygen) could be of significance too. As seagrasses substantially alter the proportions of both oxygen and inorganic carbon in the water column and respiration is a great driver of these alterations, we propose that acknowledging the presence of respiratory fluctuations in nature should be considered when estimating coastal carbon budgets. As dark respiration in field at midnight was approximately doubled from that of midday, great over-, or underestimations of the respiratory carbon dioxide release from seagrasses could be made if values are just obtained at one specific time point and considered constant.
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Affiliation(s)
- Lina M. Rasmusson
- Seagrass Ecology and Physiology Research Group, Department of Ecology, Environment and Plant Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Chiara Lauritano
- Department of Integrative Marine Ecology, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Naples, Italy
| | - Gabriele Procaccini
- Department of Integrative Marine Ecology, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Naples, Italy
| | - Martin Gullström
- Seagrass Ecology and Physiology Research Group, Department of Ecology, Environment and Plant Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Pimchanok Buapet
- Seagrass Ecology and Physiology Research Group, Department of Ecology, Environment and Plant Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
- Department of Biology, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112 Thailand
| | - Mats Björk
- Seagrass Ecology and Physiology Research Group, Department of Ecology, Environment and Plant Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
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Krause-Jensen D, Marbà N, Sanz-Martin M, Hendriks IE, Thyrring J, Carstensen J, Sejr MK, Duarte CM. Long photoperiods sustain high pH in Arctic kelp forests. SCIENCE ADVANCES 2016; 2:e1501938. [PMID: 27990490 PMCID: PMC5156516 DOI: 10.1126/sciadv.1501938] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Accepted: 10/29/2016] [Indexed: 05/11/2023]
Abstract
Concern on the impacts of ocean acidification on calcifiers, such as bivalves, sea urchins, and foraminifers, has led to efforts to understand the controls on pH in their habitats, which include kelp forests and seagrass meadows. The metabolism of these habitats can lead to diel fluctuation in pH with increases during the day and declines at night, suggesting no net effect on pH at time scales longer than daily. We examined the capacity of subarctic and Arctic kelps to up-regulate pH in situ and experimentally tested the role of photoperiod in determining the capacity of Arctic macrophytes to up-regulate pH. Field observations at photoperiods of 15 and 24 hours in Greenland combined with experimental manipulations of photoperiod show that photoperiods longer than 21 hours, characteristic of Arctic summers, are conducive to sustained up-regulation of pH by kelp photosynthesis. We report a gradual increase in pH of 0.15 units and a parallel decline in pCO2 of 100 parts per million over a 10-day period in an Arctic kelp forest over midsummer, with ample scope for continued pH increase during the months of continuous daylight. Experimental increase in CO2 concentration further stimulated the capacity of macrophytes to deplete CO2 and increase pH. We conclude that long photoperiods in Arctic summers support sustained up-regulation of pH in kelp forests, with potential benefits for calcifiers, and propose that this mechanism may increase with the projected expansion of Arctic vegetation in response to warming and loss of sea ice.
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Affiliation(s)
- Dorte Krause-Jensen
- Arctic Research Centre, Aarhus University, Ny Munkegade 114, Building 1540, 8000 Århus C, Denmark
- Department of Bioscience, Aarhus University, Vejlsøvej 25, DK-8600 Silkeborg, Denmark
| | - Núria Marbà
- Department of Global Change Research, Institut Mediterrani d’Estudis Avançats (Consejo Superior de Investigaciones Científicas–Universidad de las Islas Baleares), Miquel Marquès 21, 07190 Esporles, Spain
| | - Marina Sanz-Martin
- Department of Global Change Research, Institut Mediterrani d’Estudis Avançats (Consejo Superior de Investigaciones Científicas–Universidad de las Islas Baleares), Miquel Marquès 21, 07190 Esporles, Spain
- Facultat de Geologia, Universitat de Barcelona, 08028 Barcelona, Spain
| | - Iris E. Hendriks
- Department of Global Change Research, Institut Mediterrani d’Estudis Avançats (Consejo Superior de Investigaciones Científicas–Universidad de las Islas Baleares), Miquel Marquès 21, 07190 Esporles, Spain
| | - Jakob Thyrring
- Arctic Research Centre, Aarhus University, Ny Munkegade 114, Building 1540, 8000 Århus C, Denmark
- Department of Bioscience, Aarhus University, Vejlsøvej 25, DK-8600 Silkeborg, Denmark
| | - Jacob Carstensen
- Department of Bioscience, Aarhus University, Frederiksborgvej 399, DK-4000 Roskilde, Denmark
| | - Mikael Kristian Sejr
- Arctic Research Centre, Aarhus University, Ny Munkegade 114, Building 1540, 8000 Århus C, Denmark
- Department of Bioscience, Aarhus University, Vejlsøvej 25, DK-8600 Silkeborg, Denmark
| | - Carlos M. Duarte
- King Abdullah University of Science and Technology, Red Sea Research Center, Thuwal 23955-6900, Kingdom of Saudi Arabia
- Faculty of Biosciences, Fisheries and Economics, University of Tromsø, Tromsø, Norway
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Seagrass Ecosystem Services and Their Variability across Genera and Geographical Regions. PLoS One 2016; 11:e0163091. [PMID: 27732600 PMCID: PMC5061329 DOI: 10.1371/journal.pone.0163091] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Accepted: 09/02/2016] [Indexed: 12/03/2022] Open
Abstract
Threats to and loss of seagrass ecosystems globally, impact not only natural resources but also the lives of people who directly or indirectly depend on these systems. Seagrass ecosystems play a multi-functional role in human well-being, e.g. food through fisheries, control of erosion and protection against floods. Quantifying these services reveals their contributions to human well-being and helps justify seagrass conservation. There has been no comprehensive assessment as to whether seagrass ecosystem services are perceived to vary over the globe or amongst genera. Our study compiles the most complete list of ecosystem services provided by seagrasses so far, including bioregional- and genus-specific information from expert opinion and published studies. Several seagrass ecosystem services vary considerably in their (known) provision across genera and over the globe. Seagrasses genera are clearly not all equal with regard to the ecosystem services they provide. As seagrass genera are not evenly distributed over all bioregions, the presence of an ecosystem service sometimes depends on the genera present. Larger sized seagrass genera (e.g. Posidonia, Enhalus) are perceived to provide more substantial and a wider variety of ecosystem services than smaller species (e.g. Halophila, Lepilaena). Nevertheless, smaller species provide important services. Our findings point out data gaps, provide new insight for more efficient management and recommend caution in economic valuation of seagrass services worldwide.
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Buapet P, Björk M. The role of O2 as an electron acceptor alternative to CO2 in photosynthesis of the common marine angiosperm Zostera marina L. PHOTOSYNTHESIS RESEARCH 2016; 129:59-69. [PMID: 27125819 DOI: 10.1007/s11120-016-0268-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2015] [Accepted: 04/19/2016] [Indexed: 06/05/2023]
Abstract
This study investigates the role of O2 as an electron acceptor alternative to CO2 in photosynthesis of the common marine angiosperm Zostera marina L. Electron transport rates (ETRs) and non-photochemical quenching (NPQ) of Z. marina were measured under saturating irradiance in synthetic seawater containing 2.2 mM DIC and no DIC with different O2 levels (air-equilibrated levels, 3 % of air equilibrium and restored air-equilibrated levels). Lowering O2 did not affect ETR when DIC was provided, while it caused a decrease in ETR and an increase in NPQ in DIC-free media, indicating that O2 acted as an alternative electron acceptor under low DIC. The ETR and NPQ as a function of irradiance were subsequently assessed in synthetic seawater containing (1) 2.2 mM DIC, air-equilibrated O2; (2) saturating CO2, no O2; and (3) no DIC, air-equilibrated O2. These treatments were combined with glycolaldehyde pre-incubation. Glycolaldehyde caused a marked decrease in ETR in DIC-free medium, indicating significant electron flow supported by photorespiration. Combining glycolaldehyde with O2 depletion completely suppressed ETR suggesting the operation of the Mehler reaction, a possibility supported by the photosynthesis-dependent superoxide production. However, no notable effect of suppressing the Mehler reaction on NPQ was observed. It is concluded that during DIC-limiting conditions, such as those frequently occurring in the habitats of Z. marina, captured light energy exceeds what is utilised for the assimilation of available carbon, and photorespiration is a major alternative electron acceptor, while the contribution of the Mehler reaction is minor.
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Affiliation(s)
- Pimchanok Buapet
- Department of Biology, Faculty of Science, Prince of Songkla University, Hat Yai, 90112, Songkhla, Thailand.
| | - Mats Björk
- Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, SE-106 91, Sweden
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Hodges M, Dellero Y, Keech O, Betti M, Raghavendra AS, Sage R, Zhu XG, Allen DK, Weber APM. Perspectives for a better understanding of the metabolic integration of photorespiration within a complex plant primary metabolism network. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:3015-26. [PMID: 27053720 DOI: 10.1093/jxb/erw145] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Photorespiration is an essential high flux metabolic pathway that is found in all oxygen-producing photosynthetic organisms. It is often viewed as a closed metabolic repair pathway that serves to detoxify 2-phosphoglycolic acid and to recycle carbon to fuel the Calvin-Benson cycle. However, this view is too simplistic since the photorespiratory cycle is known to interact with several primary metabolic pathways, including photosynthesis, nitrate assimilation, amino acid metabolism, C1 metabolism and the Krebs (TCA) cycle. Here we will review recent advances in photorespiration research and discuss future priorities to better understand (i) the metabolic integration of the photorespiratory cycle within the complex network of plant primary metabolism and (ii) the importance of photorespiration in response to abiotic and biotic stresses.
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Affiliation(s)
- Michael Hodges
- Institute of Plant Sciences Paris-Saclay, Université Paris-Sud, CNRS, INRA, Université d'Evry, 91405 Orsay Cedex, France
| | - Younès Dellero
- Institute of Plant Sciences Paris-Saclay, Université Paris-Sud, CNRS, INRA, Université d'Evry, 91405 Orsay Cedex, France
| | - Olivier Keech
- Department of Plant Physiology, Umeå Plant Science Centre, Umeå University, SE-90187 Umeå, Sweden
| | - Marco Betti
- Departamento de Bioquímica Vegetal y Biología Molecular, Facultad de Química, Universidad de Sevilla, 141012 Sevilla, Spain
| | - Agepati S Raghavendra
- School of Life Sciences, Department of Plant Sciences, University of Hyderabad, Hyderabad 500046, India
| | - Rowan Sage
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, ON M5S3B2, Canada
| | - Xin-Guang Zhu
- CAS-MPG Partner Institutes for Computational Biology, Shanghai Institutes for Biological Sciences, CAS, Shanghai 200031, China
| | - Doug K Allen
- United States Department of Agriculture-Agricultural Research Service, Plant Genetics Research Unit, Donald Danforth Plant Science Center, St Louis, MO 63132, USA
| | - Andreas P M Weber
- Institute of Plant Biochemistry, Cluster of Excellence on Plant Science (CEPLAS), Heinrich-Heine-Universität, Universitätsstraße 1, and Cluster of Excellence on Plant Sciences, 40225 Düsseldorf, Germany
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Van Alstyne KL, Nelson TA, Ridgway RL. Environmental Chemistry and Chemical Ecology of “Green Tide” Seaweed Blooms. Integr Comp Biol 2015; 55:518-32. [DOI: 10.1093/icb/icv035] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Burnell OW, Connell SD, Irving AD, Watling JR, Russell BD. Contemporary reliance on bicarbonate acquisition predicts increased growth of seagrass Amphibolis antarctica in a high-CO2 world. CONSERVATION PHYSIOLOGY 2014; 2:cou052. [PMID: 27293673 PMCID: PMC4732469 DOI: 10.1093/conphys/cou052] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Revised: 07/30/2014] [Accepted: 10/16/2014] [Indexed: 05/30/2023]
Abstract
Rising atmospheric CO2 is increasing the availability of dissolved CO2 in the ocean relative to HCO3 (-). Currently, many marine primary producers use HCO3 (-) for photosynthesis, but this is energetically costly. Increasing passive CO2 uptake relative to HCO3 (-) pathways could provide energy savings, leading to increased productivity and growth of marine plants. Inorganic carbon-uptake mechanisms in the seagrass Amphibolis antarctica were determined using the carbonic anhydrase inhibitor acetazolamide (AZ) and the buffer tris(hydroxymethyl)aminomethane (TRIS). Amphibolis antarctica seedlings were also maintained in current and forecasted CO2 concentrations to measure their physiology and growth. Photosynthesis of A. antarctica was significantly reduced by AZ and TRIS, indicating utilization of HCO3 (-)-uptake mechanisms. When acclimated plants were switched between CO2 treatments, the photosynthetic rate was dependent on measurement conditions but not growth conditions, indicating a dynamic response to changes in dissolved CO2 concentration, rather than lasting effects of acclimation. At forecast CO2 concentrations, seedlings had a greater maximum electron transport rate (1.4-fold), photosynthesis (2.1-fold), below-ground biomass (1.7-fold) and increase in leaf number (2-fold) relative to plants in the current CO2 concentration. The greater increase in photosynthesis (measured as O2 production) compared with the electron transport rate at forecasted CO2 concentration suggests that photosynthetic efficiency increased, possibly due to a decrease in photorespiration. Thus, it appears that the photosynthesis and growth of seagrasses reliant on energetically costly HCO3 (-) acquisition, such as A. antarctica, might increase at forecasted CO2 concentrations. Greater growth might enhance the future prosperity and rehabilitation of these important habitat-forming plants, which have experienced declines of global significance.
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Affiliation(s)
- Owen W. Burnell
- School of Earth & Environmental Sciences, University of Adelaide, Adelaide, SA 5005, Australia
| | - Sean D. Connell
- School of Earth & Environmental Sciences, University of Adelaide, Adelaide, SA 5005, Australia
| | - Andrew D. Irving
- School of Medical and Applied Sciences, Central Queensland University, Bruce Highway, Rockhampton, QLD 4702, Australia
| | - Jennifer R. Watling
- School of Earth & Environmental Sciences, University of Adelaide, Adelaide, SA 5005, Australia
| | - Bayden D. Russell
- School of Earth & Environmental Sciences, University of Adelaide, Adelaide, SA 5005, Australia
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