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Ravaglioli C, De Marchi L, Anselmi S, Dattolo E, Fontanini D, Pretti C, Procaccini G, Rilov G, Renzi M, Silverman J, Bulleri F. Ocean acidification impairs seagrass performance under thermal stress in shallow and deep water. ENVIRONMENTAL RESEARCH 2024; 241:117629. [PMID: 37967703 DOI: 10.1016/j.envres.2023.117629] [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: 08/09/2023] [Revised: 10/21/2023] [Accepted: 11/07/2023] [Indexed: 11/17/2023]
Abstract
Despite the effects of ocean acidification (OA) on seagrasses have been widely investigated, predictions of seagrass performance under future climates need to consider multiple environmental factors. Here, we performed a mesocosm study to assess the effects of OA on shallow and deep Posidonia oceanica plants. The experiment was run in 2021 and repeated in 2022, a year characterized by a prolonged warm water event, to test how the effects of OA on plants are modulated by thermal stress. The response of P. oceanica to experimental conditions was investigated at different levels of biological organization. Under average seawater temperature, there were no effects of OA in both shallow and deep plants, indicating that P. oceanica is not limited by current inorganic carbon concentration, regardless of light availability. In contrast, under thermal stress, exposure of plants to OA increased lipid peroxidation and decreased photosynthetic performance, with deep plants displaying higher levels of heat stress, as indicated by the over-expression of stress-related genes and the activation of antioxidant systems. In addition, warming reduced plant growth, regardless of seawater CO2 and light levels, suggesting that thermal stress may play a fundamental role in the future development of seagrass meadows. Our results suggest that OA may exacerbate the negative effects of future warming on seagrasses.
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Affiliation(s)
- Chiara Ravaglioli
- Dipartimento di Biologia, Università di Pisa, CoNISMa, Via Derna 1, 56126, Pisa, Italy.
| | - Lucia De Marchi
- Dipartimento di Scienze Veterinarie, Università of Pisa, Via Livornese (lato monte), 56122, San Piero a Grado, Pisa, Italy.
| | - Serena Anselmi
- Bioscience Research Center, Via Aurelia Vecchia, 32, 58015, Orbetello, GR, Italy.
| | - Emanuela Dattolo
- Stazione Zoologica Anton Dohrn, Villa Comunale, 80121, Napoli, Italy; National Biodiversity Future Centre (NBFC), Palermo, Italy.
| | - Debora Fontanini
- Dipartimento di Biologia, Università di Pisa, CoNISMa, Via Derna 1, 56126, Pisa, Italy.
| | - Carlo Pretti
- Dipartimento di Scienze Veterinarie, Università of Pisa, Via Livornese (lato monte), 56122, San Piero a Grado, Pisa, Italy; Interuniversity Consortium of Marine Biology and Applied Ecology "G. Bacci" (CIBM), Viale N.Sauro 4, 57128, Livorno, Italy.
| | - Gabriele Procaccini
- Stazione Zoologica Anton Dohrn, Villa Comunale, 80121, Napoli, Italy; National Biodiversity Future Centre (NBFC), Palermo, Italy.
| | - Gil Rilov
- National Institute of Oceanography, Israel Oceanographic and Limnological Research, Haifa, Israel.
| | - Monia Renzi
- Dipartimento di Scienze Della Vita, Università di Trieste, Via Giorgieri, 10, 34127, Trieste, Italy.
| | - Jacob Silverman
- National Institute of Oceanography, Israel Oceanographic and Limnological Research, Haifa, Israel.
| | - Fabio Bulleri
- Dipartimento di Biologia, Università di Pisa, CoNISMa, Via Derna 1, 56126, Pisa, Italy; Centro Interdipartimentale di Ricerca per Lo Studio Degli Effetti Del Cambiamento Climatico (CIRSEC), Università di Pisa, Italy.
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2
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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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Litsi-Mizan V, Efthymiadis PT, Gerakaris V, Serrano O, Tsapakis M, Apostolaki ET. Decline of seagrass (Posidonia oceanica) production over two decades in the face of warming of the Eastern Mediterranean Sea. THE NEW PHYTOLOGIST 2023; 239:2126-2137. [PMID: 37366062 DOI: 10.1111/nph.19084] [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: 02/13/2023] [Accepted: 05/31/2023] [Indexed: 06/28/2023]
Abstract
The response of Posidonia oceanica meadows to global warming of the Eastern Mediterranean Sea, where the increase in sea surface temperature (SST) is particularly severe, is poorly investigated. Here, we reconstructed the long-term P. oceanica production in 60 meadows along the Greek Seas over two decades (1997-2018), using lepidochronology. We determined the effect of warming on production by reconstructing the annual and maximum (i.e. August) SST, considering the role of other production drivers related to water quality (i.e. Chla, suspended particulate matter, Secchi depth). Grand mean (±SE) production across all sites and the study period was 48 ± 1.1 mg DW per shoot yr-1 . Production over the last two decades followed a trajectory of decrease, which was related to the concurrent increase in annual SST and SSTaug . Annual SST > 20°C and SSTaug > 26.5°C was related to production decline (GAMM, P < 0.05), while the rest of the tested factors did not help explain the production pattern. Our results indicate a persistent and increasing threat for Eastern Mediterranean meadows, drawing attention to management authorities, highlighting the necessity of reducing local impacts to enhance the resilience of seagrass meadows to global change threats.
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Affiliation(s)
- Victoria Litsi-Mizan
- Biology Department, University of Crete, Voutes University Campus, PO Box 2208, Heraklion, Crete, GR-70013, Greece
- Institute of Oceanography, Hellenic Centre for Marine Research, PO Box 2214, Heraklion, Crete, GR-71003, Greece
| | - Pavlos T Efthymiadis
- Institute of Oceanography, Hellenic Centre for Marine Research, PO Box 2214, Heraklion, Crete, GR-71003, Greece
| | - Vasilis Gerakaris
- Institute of Oceanography, Hellenic Centre for Marine Research, PO Box 712, Anavyssos, Attiki, 19013, Greece
| | - Oscar Serrano
- Centre of Advanced Studies of Blanes (CEAB-CSIC), Cala Sant Francesc 14, Blanes, 17300, Spain
- School of Science & Centre for Marine Ecosystems Research, Edith Cowan University, Joondalup, WA, 6027, Australia
| | - Manolis Tsapakis
- Institute of Oceanography, Hellenic Centre for Marine Research, PO Box 2214, Heraklion, Crete, GR-71003, Greece
| | - Eugenia T Apostolaki
- Institute of Oceanography, Hellenic Centre for Marine Research, PO Box 2214, Heraklion, Crete, GR-71003, Greece
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4
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Minguito-Frutos M, Adams MP, Alcoverro T, Vilas MP, Alonso D, Mayol E, Bernardeu-Esteller J, Marín-Guirao L, Ruiz JM, Boada J. Quantifying the role of photoacclimation and self-facilitation for seagrass resilience to light deprivation. FRONTIERS IN PLANT SCIENCE 2023; 14:1186538. [PMID: 37546272 PMCID: PMC10401047 DOI: 10.3389/fpls.2023.1186538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Accepted: 06/28/2023] [Indexed: 08/08/2023]
Abstract
Introduction Light gradients are ubiquitous in marine systems as light reduces exponentially with depth. Seagrasses have a set of mechanisms that help them to cope with light stress gradients. Physiological photoacclimation and clonal integration help to maximize light capture and minimize carbon losses. These mechanisms can shape plants minimum light requirements (MLR), which establish critical thresholds for seagrass survival and help us predict ecosystem responses to the alarming reduction in light availability. Methods Using the seagrass Cymodocea nodosa as a case study, we compare the MLR under different carbon model scenarios, which include photoacclimation and/or self-facilitation (based on clonal integration) and that where parameterized with values from field experiments. Results Physiological photoacclimation conferred plants with increased tolerance to reducing light, approximately halving their MLR from 5-6% surface irradiance (SI) to ≈ 3% SI. In oligotrophic waters, this change in MLR could translate to an increase of several meters in their depth colonization limit. In addition, we show that reduced mortality rates derived from self-facilitation mechanisms (promoted by high biomass) induce bistability of seagrass meadows along the light stress gradient, leading to abrupt shifts and hysteretic behaviors at their deep limit. Discussion The results from our models point to (i) the critical role of physiological photoacclimation in conferring greater resistance and ability to recover (i.e., resilience), to seagrasses facing light deprivation and (ii) the importance of self-facilitating reinforcing mechanisms in driving the resilience and recovery of seagrass systems exposed to severe light reduction events.
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Affiliation(s)
- Mario Minguito-Frutos
- Centre d’Estudis Avançats de Blanes (CEAB-CSIC), Carrer d’Accés a la cala Sant Francesc, Girona, Spain
| | - Matthew P. Adams
- School of Mathematical Sciences, Queensland University of Technology, Brisbane, QLD, Australia
- Centre for Data Science, Queensland University of Technology, Brisbane, QLD, Australia
- School of Chemical Engineering, The University of Queensland, St. Lucia, QLD, Australia
| | - Teresa Alcoverro
- Centre d’Estudis Avançats de Blanes (CEAB-CSIC), Carrer d’Accés a la cala Sant Francesc, Girona, Spain
| | - María P. Vilas
- Department of Environment and Science, Queensland Government, Brisbane, QLD, Australia
| | - David Alonso
- Centre d’Estudis Avançats de Blanes (CEAB-CSIC), Carrer d’Accés a la cala Sant Francesc, Girona, Spain
| | - Elvira Mayol
- Departament de Biologia Evolutiva, Ecologia i Ciències Ambientals, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
- Department of Global Change Research, IMEDEA (Mediterranean Institute for Advanced Studies) (UIB-CSIC), Esporles, Spain
| | - Jaime Bernardeu-Esteller
- Seagrass Ecology Group, Oceanographic Center of Murcia, Spanish Institute of Oceanography (IEO-CSIC), Murcia, Spain
| | - Lázaro Marín-Guirao
- Seagrass Ecology Group, Oceanographic Center of Murcia, Spanish Institute of Oceanography (IEO-CSIC), Murcia, Spain
| | - Juan M. Ruiz
- Seagrass Ecology Group, Oceanographic Center of Murcia, Spanish Institute of Oceanography (IEO-CSIC), Murcia, Spain
| | - Jordi Boada
- Centre d’Estudis Avançats de Blanes (CEAB-CSIC), Carrer d’Accés a la cala Sant Francesc, Girona, Spain
- Laboratoire d’Océanographie de Villefranche-sur-Mer, CNRS, Sorbonne Université, Villefranche sur mer, France
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Guo Z, Still CJ, Lee CKF, Ryu Y, Blonder B, Wang J, Bonebrake TC, Hughes A, Li Y, Yeung HCH, Zhang K, Law YK, Lin Z, Wu J. Does plant ecosystem thermoregulation occur? An extratropical assessment at different spatial and temporal scales. THE NEW PHYTOLOGIST 2023; 238:1004-1018. [PMID: 36495263 DOI: 10.1111/nph.18632] [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: 08/09/2022] [Accepted: 11/11/2022] [Indexed: 06/17/2023]
Abstract
To what degree plant ecosystems thermoregulate their canopy temperature (Tc ) is critical to assess ecosystems' metabolisms and resilience with climate change, but remains controversial, with opinions from no to moderate thermoregulation capability. With global datasets of Tc , air temperature (Ta ), and other environmental and biotic variables from FLUXNET and satellites, we tested the 'limited homeothermy' hypothesis (indicated by Tc & Ta regression slope < 1 or Tc < Ta around midday) across global extratropics, including temporal and spatial dimensions. Across daily to weekly and monthly timescales, over 80% of sites/ecosystems have slopes ≥1 or Tc > Ta around midday, rejecting the above hypothesis. For those sites unsupporting the hypothesis, their Tc -Ta difference (ΔT) exhibits considerable seasonality that shows negative, partial correlations with leaf area index, implying a certain degree of thermoregulation capability. Spatially, site-mean ΔT exhibits larger variations than the slope indicator, suggesting ΔT is a more sensitive indicator for detecting thermoregulatory differences across biomes. Furthermore, this large spatial-wide ΔT variation (0-6°C) is primarily explained by environmental variables (38%) and secondarily by biotic factors (15%). These results demonstrate diverse thermoregulation patterns across global extratropics, with most ecosystems negating the 'limited homeothermy' hypothesis, but their thermoregulation still occurs, implying that slope < 1 or Tc < Ta are not necessary conditions for plant thermoregulation.
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Affiliation(s)
- Zhengfei Guo
- School for Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Christopher J Still
- Forest Ecosystems and Society, Oregon State University, Corvallis, OR, 97331, USA
| | - Calvin K F Lee
- School for Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Youngryel Ryu
- Department of Landscape Architecture and Rural Systems Engineering, College of Agriculture and Life Sciences, Seoul National University, Gwanak-gu, Seoul, South Korea
| | - Benjamin Blonder
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA, 94720, USA
| | - Jing Wang
- School for Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Timothy C Bonebrake
- School for Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China
- Institute for Climate and Carbon Neutrality, The University of Hong Kong, Hong Kong, China
| | - Alice Hughes
- School for Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China
- Institute for Climate and Carbon Neutrality, The University of Hong Kong, Hong Kong, China
| | - Yan Li
- State Key Laboratory of Earth Surface Processes and Resources Ecology, Beijing Normal University, Beijing, 100875, China
| | - Henry C H Yeung
- School for Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Kun Zhang
- School for Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China
- Department of Mathematics, The University of Hong Kong, Hong Kong, China
| | - Ying Ki Law
- School for Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Ziyu Lin
- School for Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Jin Wu
- School for Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China
- Institute for Climate and Carbon Neutrality, The University of Hong Kong, Hong Kong, China
- State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong, China
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Lekammudiyanse MU, Saunders MI, Flint N, Irving A, Jackson EL. Simulated effects of tidal inundation and light reduction on Zostera muelleri flowering in seagrass nurseries. MARINE ENVIRONMENTAL RESEARCH 2023; 188:106010. [PMID: 37141708 DOI: 10.1016/j.marenvres.2023.106010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 04/10/2023] [Accepted: 04/27/2023] [Indexed: 05/06/2023]
Abstract
Zostera muelleri is an abundant seagrass species distributed through intertidal and shallow subtidal waters on the subtropical coasts of Australia. The vertical distribution of Zostera is likely defined by tidal influences, particularly desiccation and light reduction stresses. These stresses were expected to affect the flowering of Z. muelleri; however, it is difficult to quantify the effects of tidal inundation with field studies due to multiple confounding environmental factors affecting flowering (e.g., water temperature, herbivory, nutrients). A laboratory aquarium experiment compared the effects of two levels of tidal height (intertidal and subtidal) and light intensity (shaded and unshaded) on flowering timing, abundance, the ratio between flowering shoots and vegetative shoots, the morphology and duration of flower development. The earliest and greatest flowering intensity was recorded in the subtidal-unshaded group, with no flowers observed in the intertidal-shaded group. Notably, the peak flowering time was the same across shaded and unshaded treatments. Shading prolonged the timing of the first flowering and reduced the density of flowering shoots and spathes, while tidal inundation had a more significant effect on the density of flowering shoots and the density of spathes. Results showed that Z. muelleri could flower under low light conditions or tidal stress but not when exposed to both stresses simultaneously in a laboratory 'nursery setting'. Therefore, applying subtidal-unshaded conditions appears to be beneficial for seagrass nurseries aimed at improved flower abundance despite the plants previously being collected from and adapted to intertidal meadows. Further studies that explore the suitable conditions for triggering and optimising the flowering will be beneficial in designing cost-effective seagrass nurseries.
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Affiliation(s)
- Manuja U Lekammudiyanse
- Central Queensland University, Coastal Marine Ecosystems Research Centre, Gladstone, QLD, 4680, Australia; CSIRO Environment, Queensland Bioscience Precinct, St Lucia, QLD, 4067, Australia; Central Queensland University, School of Health, Medical and Applied Sciences, North Rockhampton, QLD, 4701, Australia.
| | - Megan I Saunders
- CSIRO Environment, Queensland Bioscience Precinct, St Lucia, QLD, 4067, Australia
| | - Nicole Flint
- Central Queensland University, Coastal Marine Ecosystems Research Centre, Gladstone, QLD, 4680, Australia; Central Queensland University, School of Health, Medical and Applied Sciences, North Rockhampton, QLD, 4701, Australia
| | - Andrew Irving
- Central Queensland University, Coastal Marine Ecosystems Research Centre, Gladstone, QLD, 4680, Australia; Central Queensland University, School of Health, Medical and Applied Sciences, North Rockhampton, QLD, 4701, Australia
| | - Emma L Jackson
- Central Queensland University, Coastal Marine Ecosystems Research Centre, Gladstone, QLD, 4680, Australia
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7
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Viana IG, Artika SR, Moreira-Saporiti A, Teichberg M. Limited trait responses of a tropical seagrass to the combination of increasing pCO2 and warming. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:472-488. [PMID: 36272111 DOI: 10.1093/jxb/erac425] [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: 03/04/2022] [Accepted: 10/20/2022] [Indexed: 06/16/2023]
Abstract
Understanding species-specific trait responses under future global change scenarios is of importance for conservation efforts and to make informed decisions within management projects. The combined and single effects of seawater acidification and warmer average temperature were investigated by means of the trait responses of Cymodocea serrulata, a tropical seagrass, under experimental conditions. After a 35 d exposure period, biochemical, morphological, and photo-physiological trait responses were measured. Overall, biochemical traits mildly responded under the individual exposure to high temperature and increasing pCO2 values. The response of C. serrulata was limited to a decrease in %C and an increase in the sucrose content in the rhizome under the high temperature treatment, 32 °C. This suggests that this temperature was lower than the maximum tolerance limit for this species. Increasing pCO2 levels increased %C in the rhizome, and also showed a significant increase in leaf δ13C values. The effects of all treatments were sublethal; however, small changes in their traits could affect the ecosystem services they provide. In particular, changes in tissue carbon concentrations may affect carbon storage capacity, one key ecosystem service. The simultaneous study of different types of trait responses contributes to establish a holistic framework of seagrass ecosystem health under climate change.
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Affiliation(s)
- Inés G Viana
- Department of Ecology and Animal Biology, University of Vigo, 36310 Vigo, Spain
- Department of Ecology, Leibniz Centre for Tropical Marine Research, Bremen, Germany
- Instituto Español de Oceanografía (IEO-CSIC), Centro Oceanográfico de A Coruña, 15001, A Coruña, Spain
| | - Suci Rahmadani Artika
- Department of Ecology, Leibniz Centre for Tropical Marine Research, Bremen, Germany
- Department of Marine Sciences, Faculty of Marine Sciences and Fisheries, Hasanuddin University, Indonesia
- Department of Marine Sciences, Faculty of Fisheries and Marine Sciences, Halu Oleo University, Indonesia
| | - Agustín Moreira-Saporiti
- Department of Ecology, Leibniz Centre for Tropical Marine Research, Bremen, Germany
- University of Bremen, Bremen, Germany
- The Ecosystems Center, Marine Biological Laboratory (MBL), Woods Hole, MA, USA
| | - Mirta Teichberg
- Department of Ecology, Leibniz Centre for Tropical Marine Research, Bremen, Germany
- The Ecosystems Center, Marine Biological Laboratory (MBL), Woods Hole, MA, USA
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8
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Qiao Y, Zhang Y, Xu S, Yue S, Zhang X, Liu M, Sun L, Jia X, Zhou Y. Multi-leveled insights into the response of the eelgrass Zostera marina L to Cu than Cd exposure. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 845:157057. [PMID: 35780896 DOI: 10.1016/j.scitotenv.2022.157057] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 06/06/2022] [Accepted: 06/25/2022] [Indexed: 06/15/2023]
Abstract
Seagrass beds are recognized as critical and among the most vulnerable habitats on the planet; seagrass colonize the coastal waters where heavy metal pollution is a serious problem. In this study, the toxic effects of copper and cadmium in the eelgrass Zostera marina L. were observed at the individual, subcellular, physiologically biochemical, and molecular levels. Both Cu and Cd stress significantly inhibited the growth and the maximal quantum yield of photosystem II (Fv/Fm); and high temperature increased the degree of heavy metal damage, while low temperatures inhibited damage. The half-effect concentration (EC50) of eelgrass was 28.9 μM for Cu and 2246.8 μM for Cd, indicating Cu was much more toxic to eelgrass than Cd. The effect of Cu and Cd on photosynthesis was synergistic. After 14 days of enrichment, the concentration of Cu in leaves and roots of Z. marina was 48 and 37 times higher than that in leaf sheath, and 14 and 11 times higher than that in rhizome; and the order of Cd concentration in the organs was root > leaf > rhizome > sheath. Heavy metal uptake mainly occurred in the organelles, and Cd enrichment also occurred to a certain extent in the cytoplasm. Transcriptome results showed that a number of photosynthesis-related KEGG enrichment pathways and GO terms were significantly down-regulated under Cd stress, suggesting that the photosynthetic system of eelgrass was severely damaged at the transcriptome level, which was consistent with the significant inhibition of Fv/Fm and leaf yellowing. Under Cu stress, the genes related to glutathione metabolic pathway were significantly up-regulated, together with the increased autioxidant enzyme activity of GSH-PX. In addition, the results of recovery experiment indicated that the damage caused by short-term Cd and Cu stress under EC50 was reversible. These results provide heavy metal toxic effects at multiple levels and information relating to the heavy metal resistance strategies evolved by Z. marina to absorb and isolate heavy metals, and highlight the phytoremediation potential of this species especially for Cd.
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Affiliation(s)
- Yongliang Qiao
- School of Environment and Safety Engineering, Qingdao University of Science and Technology, Qingdao 266042, China; 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; University of Chinese Academy of Sciences, Beijing 100049, China; Shandong Province Key Laboratory of Experimental Marine Biology, Qingdao 266071, China
| | - Yu 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; University of Chinese Academy of Sciences, Beijing 100049, China; Shandong Province Key Laboratory of Experimental Marine Biology, Qingdao 266071, China
| | - Shaochun Xu
- 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; University of Chinese Academy of Sciences, Beijing 100049, China; Shandong Province Key Laboratory of Experimental Marine Biology, Qingdao 266071, China
| | - Shidong Yue
- 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; University of Chinese Academy of Sciences, Beijing 100049, China; Shandong Province Key Laboratory of Experimental Marine Biology, Qingdao 266071, China
| | - 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; University of Chinese Academy of Sciences, Beijing 100049, China; Shandong Province Key Laboratory of Experimental Marine Biology, Qingdao 266071, China
| | - Mingjie Liu
- 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; University of Chinese Academy of Sciences, Beijing 100049, China; Shandong Province Key Laboratory of Experimental Marine Biology, Qingdao 266071, China
| | - Lingling Sun
- Public Tech-Supporting Center, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
| | - Xiaoping Jia
- School of Environment and Safety Engineering, Qingdao University of Science and Technology, Qingdao 266042, 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; University of Chinese Academy of Sciences, Beijing 100049, China; Shandong Province Key Laboratory of Experimental Marine Biology, Qingdao 266071, China.
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9
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Lebrasse MC, Schaeffer BA, Zimmerman RC, Hill VJ, Coffer MM, Whitman PJ, Salls WB, Graybill DD, Osburn CL. Simulated response of St. Joseph Bay, Florida, seagrass meadows and their belowground carbon to anthropogenic and climate impacts. MARINE ENVIRONMENTAL RESEARCH 2022; 179:105694. [PMID: 35850077 PMCID: PMC9924051 DOI: 10.1016/j.marenvres.2022.105694] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 06/22/2022] [Accepted: 06/23/2022] [Indexed: 05/26/2023]
Abstract
Seagrass meadows are degraded globally and continue to decline in areal extent due to human pressures and climate change. This study used the bio-optical model GrassLight to explore the impact of climate change and anthropogenic stressors on seagrass extent, leaf area index (LAI) and belowground organic carbon (BGC) in St. Joseph Bay, Florida, using water quality data and remotely-sensed sea surface temperature (SST) from 2002 to 2020. Model predictions were compared with satellite-derived measurements of seagrass extent and shoot density from the Landsat images for the same period. The GrassLight-derived area of potential seagrass habitat ranged from 36.2 km2 to 39.2 km2, averaging 38.0 ± 0.8 km2 compared to an observed seagrass extent of 23.0 ± 3.0 km2 derived from Landsat (range = 17.9-27.4 km2). GrassLight predicted a mean seagrass LAI of 2.7 m2 leaf m-2 seabed, compared to a mean LAI of 1.9 m2 m-2 estimated from Landsat, indicating that seagrass density in St. Joseph Bay may have been below its light-limited ecological potential. Climate and anthropogenic change simulations using GrassLight predicted the impact of changes in temperature, pH, chlorophyll a, chromophoric dissolved organic matter and turbidity on seagrass meadows. Simulations predicted a 2-8% decline in seagrass extent with rising temperatures that was offset by a 3-11% expansion in seagrass extent in response to ocean acidification when compared to present conditions. Simulations of water quality impacts showed that a doubling of turbidity would reduce seagrass extent by 18% and total leaf area by 21%. Combining climate and water quality scenarios showed that ocean acidification may increase seagrass productivity to offset the negative effects of both thermal stress and declining water quality on the seagrasses growing in St. Joseph Bay. This research highlights the importance of considering multiple limiting factors in understanding the effects of environmental change on seagrass ecosystems.
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Affiliation(s)
- Marie Cindy Lebrasse
- Oak Ridge Institute for Science and Education, U.S. Environmental Protection Agency, Durham, NC, USA; Department of Marine, Earth and Atmospheric Sciences, North Carolina State University, Raleigh, NC, USA.
| | - Blake A Schaeffer
- U.S. Environmental Protection Agency, Office of Research and Development, Durham, NC, USA
| | - Richard C Zimmerman
- Department of Ocean and Earth Sciences, Old Dominion University, Norfolk, VA, USA
| | - Victoria J Hill
- Department of Ocean and Earth Sciences, Old Dominion University, Norfolk, VA, USA
| | - Megan M Coffer
- Oak Ridge Institute for Science and Education, U.S. Environmental Protection Agency, Durham, NC, USA
| | - Peter J Whitman
- Oak Ridge Institute for Science and Education, U.S. Environmental Protection Agency, Durham, NC, USA
| | - Wilson B Salls
- U.S. Environmental Protection Agency, Office of Research and Development, Durham, NC, USA
| | - David D Graybill
- Oak Ridge Institute for Science and Education, U.S. Environmental Protection Agency, Durham, NC, USA
| | - Christopher L Osburn
- Department of Marine, Earth and Atmospheric Sciences, North Carolina State University, Raleigh, NC, USA
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10
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Ocean Acidification Alleviates Dwarf Eelgrass (Zostera noltii) Lipid Landscape Remodeling under Warming Stress. BIOLOGY 2022; 11:biology11050780. [PMID: 35625507 PMCID: PMC9138486 DOI: 10.3390/biology11050780] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Revised: 05/17/2022] [Accepted: 05/17/2022] [Indexed: 11/17/2022]
Abstract
Coastal seagrass meadows provide a variety of essential ecological and economic services, including nursery grounds, sediment stabilization, nutrient cycling, coastal protection, and blue carbon sequestration. However, these ecosystems are highly threatened by ongoing climatic change. This study was aimed to understand how the dwarf eelgrass Zostera noltii leaf lipid landscapes are altered under predicted ocean warming (+4 °C) and hypercapnic (ΔpH 0.4) conditions. Warming and hypercapnic conditions were found to induce a severe reduction in the leaf total fatty acid, though the combined treatment substantially alleviated this depletion. The lipid discrimination revealed a significant increase in the relative monogalactosyldiacylglycerol (MGDG) content in both hypercapnic and warming conditions, allied to plastidial membrane stabilization mechanisms. Hypercapnia also promoted enhanced phosphatidylglycerol (PG) leaf contents, a mechanism often associated with thylakoid reinvigoration. In addition to changing the proportion of storage, galacto- and phospholipids, the tested treatments also impacted the FA composition of all lipid classes, with warming exposure leading to decreases in polyunsaturated fatty acids (PUFAs); however, the combination of both stress conditions alleviated this effect. The observed galactolipid and phospholipid PUFA decreases are compatible with a homeoviscous adaptation, allowing for the maintenance of membrane stability by counteracting excessive membrane fluidity. Neutral lipid contents were substantially increased under warming conditions, especially in C18 fatty acids (C18), impairing their use as substrates for fatty acylated derivatives essential for maintaining the osmotic balance of cells. An analysis of the phospholipid and galactolipid fatty acid profiles as a whole revealed a higher degree of discrimination, highlighting the higher impact of warming and the proposed stress alleviation effect induced by increased water-dissolved CO2 availability. Still, it is essential to remember that the pace at which the ocean is warming can overcome the ameliorative capacity induced by higher CO2 availability, leaving seagrasses under severe heat stress beyond their lipid remodeling capacity.
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11
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Deguette A, Barrote I, Silva J. Physiological and morphological effects of a marine heatwave on the seagrass Cymodocea nodosa. Sci Rep 2022; 12:7950. [PMID: 35562537 PMCID: PMC9106744 DOI: 10.1038/s41598-022-12102-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 05/05/2022] [Indexed: 11/09/2022] Open
Abstract
Marine heatwaves (MHWs) are increasing in frequency and intensity as part of climate change, yet their impact on seagrass is poorly known. The present work evaluated the physiological and morphological responses of Cymodocea nodosa to a MHW. C. nodosa shoots were transplanted into a mesocosm facility. To simulate a MHW, water temperature was raised from 20 to 28 °C, kept 7 days at 28 °C, cooled down back to 20 °C and then maintained at 20 °C during an 8-day recovery period. The potentially stressful effects of the simulated heatwave on the photosynthetic performance, antioxidative-stress level and area vs dry weight ratio of leaves were investigated. The maximum quantum yield of photosystem II (ΦPSII) increased during the heatwave, allowing the plants to maintain their photosynthetic activity at control level. Negative effects on the photosynthetic performance and leaf biomass of C. nodosa were observed during the recovery period. No significant oxidative stress was observed throughout the experiment. Overall, although C. nodosa showed a relative tolerance to MHWs compared to other species, its population in Ria Formosa is likely to be negatively affected by the forecasted climate change scenarios.
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Affiliation(s)
- Alizé Deguette
- Centre of Marine Sciences, University of Algarve, Campus of Gambelas, 8005-139, Faro, Portugal
| | - Isabel Barrote
- Centre of Marine Sciences, University of Algarve, Campus of Gambelas, 8005-139, Faro, Portugal.,Faculty of Science and Technology, University of Algarve, Campus of Gambelas, 8005-139, Faro, Portugal
| | - João Silva
- Centre of Marine Sciences, University of Algarve, Campus of Gambelas, 8005-139, Faro, Portugal.
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12
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Turschwell MP, Connolly SR, Schäfer RB, De Laender F, Campbell MD, Mantyka-Pringle C, Jackson MC, Kattwinkel M, Sievers M, Ashauer R, Côté IM, Connolly RM, van den Brink PJ, Brown CJ. Interactive effects of multiple stressors vary with consumer interactions, stressor dynamics and magnitude. Ecol Lett 2022; 25:1483-1496. [PMID: 35478314 PMCID: PMC9320941 DOI: 10.1111/ele.14013] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 03/30/2022] [Accepted: 04/04/2022] [Indexed: 01/09/2023]
Abstract
Predicting the impacts of multiple stressors is important for informing ecosystem management but is impeded by a lack of a general framework for predicting whether stressors interact synergistically, additively or antagonistically. Here, we use process-based models to study how interactions generalise across three levels of biological organisation (physiological, population and consumer-resource) for a two-stressor experiment on a seagrass model system. We found that the same underlying processes could result in synergistic, additive or antagonistic interactions, with interaction type depending on initial conditions, experiment duration, stressor dynamics and consumer presence. Our results help explain why meta-analyses of multiple stressor experimental results have struggled to identify predictors of consistently non-additive interactions in the natural environment. Experiments run over extended temporal scales, with treatments across gradients of stressor magnitude, are needed to identify the processes that underpin how stressors interact and provide useful predictions to management.
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Affiliation(s)
- Mischa P Turschwell
- Coastal and Marine Research Centre, School of Environment and Science, Australian Rivers Institute, Griffith University, Gold Coast, Queensland, Australia
| | - Sean R Connolly
- Naos Marine Laboratories, Smithsonian Tropical Research Institute, Balboa Ancón, Republic of Panama.,College of Science and Engineering, James Cook University, Townsville, Australia
| | - Ralf B Schäfer
- Quantitative Landscape Ecology, iES-Institute for Environmental Sciences, University Koblenz-Landau, Landau in der Pfalz, Germany
| | - Frederik De Laender
- Research Unit of Environmental and Evolutionary Biology, Namur Institute of Complex Systems and Institute of Life, Earth, and the Environment, University of Namur, Namur, Belgium
| | - Max D Campbell
- Coastal and Marine Research Centre, School of Environment and Science, Australian Rivers Institute, Griffith University, Gold Coast, Queensland, Australia
| | - Chrystal Mantyka-Pringle
- Wildlife Conservation Society Canada, Whitehorse, Yukon Territory, Canada.,School of Environment and Sustainability, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | | | - Mira Kattwinkel
- Quantitative Landscape Ecology, iES-Institute for Environmental Sciences, University Koblenz-Landau, Landau in der Pfalz, Germany
| | - Michael Sievers
- Coastal and Marine Research Centre, School of Environment and Science, Australian Rivers Institute, Griffith University, Gold Coast, Queensland, Australia
| | - Roman Ashauer
- Environment Department, University of York, York, UK.,Syngenta Crop Protection AG, Basel, Switzerland
| | - Isabelle M Côté
- Earth to Ocean Research Group, Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Rod M Connolly
- Coastal and Marine Research Centre, School of Environment and Science, Australian Rivers Institute, Griffith University, Gold Coast, Queensland, Australia
| | - Paul J van den Brink
- Aquatic Ecology and Water Quality Management Group, Wageningen University, Wageningen, The Netherlands.,Wageningen Environmental Research, Wageningen, The Netherlands
| | - Christopher J Brown
- Coastal and Marine Research Centre, School of Environment and Science, Australian Rivers Institute, Griffith University, Gold Coast, Queensland, Australia
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13
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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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14
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Detecting Multi-Decadal Changes in Seagrass Cover in Tauranga Harbour, New Zealand, Using Landsat Imagery and Boosting Ensemble Classification Techniques. ISPRS INTERNATIONAL JOURNAL OF GEO-INFORMATION 2021. [DOI: 10.3390/ijgi10060371] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Seagrass provides a wide range of essential ecosystem services, supports climate change mitigation, and contributes to blue carbon sequestration. This resource, however, is undergoing significant declines across the globe, and there is an urgent need to develop change detection techniques appropriate to the scale of loss and applicable to the complex coastal marine environment. Our work aimed to develop remote-sensing-based techniques for detection of changes between 1990 and 2019 in the area of seagrass meadows in Tauranga Harbour, New Zealand. Four state-of-the-art machine-learning models, Random Forest (RF), Support Vector Machine (SVM), Extreme Gradient Boost (XGB), and CatBoost (CB), were evaluated for classification of seagrass cover (presence/absence) in a Landsat 8 image from 2019, using near-concurrent Ground-Truth Points (GTPs). We then used the most accurate one of these models, CB, with historic Landsat imagery supported by classified aerial photographs for an estimation of change in cover over time. The CB model produced the highest accuracies (precision, recall, F1 scores of 0.94, 0.96, and 0.95 respectively). We were able to use Landsat imagery to document the trajectory and spatial distribution of an approximately 50% reduction in seagrass area from 2237 ha to 1184 ha between the years 1990–2019. Our illustration of change detection of seagrass in Tauranga Harbour suggests that machine-learning techniques, coupled with historic satellite imagery, offers potential for evaluation of historic as well as ongoing seagrass dynamics.
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15
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Nguyen HM, Ralph PJ, Marín-Guirao L, Pernice M, Procaccini G. Seagrasses in an era of ocean warming: a review. Biol Rev Camb Philos Soc 2021; 96:2009-2030. [PMID: 34014018 DOI: 10.1111/brv.12736] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 05/06/2021] [Accepted: 05/07/2021] [Indexed: 12/15/2022]
Abstract
Seagrasses are valuable sources of food and habitat for marine life and are one of Earth's most efficient carbon sinks. However, they are facing a global decline due to ocean warming and eutrophication. In the last decade, with the advent of new technology and molecular advances, there has been a dramatic increase in the number of studies focusing on the effects of ocean warming on seagrasses. Here, we provide a comprehensive review of the future of seagrasses in an era of ocean warming. We have gathered information from published studies to identify potential commonalities in the effects of warming and the responses of seagrasses across four distinct levels: molecular, biochemical/physiological, morphological/population, and ecosystem/planetary. To date, we know that although warming strongly affects seagrasses at all four levels, seagrass responses diverge amongst species, populations, and over depths. Furthermore, warming alters seagrass distribution causing massive die-offs in some seagrass populations, whilst also causing tropicalization and migration of temperate species. In this review, we evaluate the combined effects of ocean warming with other environmental stressors and emphasize the need for multiple-stressor studies to provide a deeper understanding of seagrass resilience. We conclude by discussing the most significant knowledge gaps and future directions for seagrass research.
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Affiliation(s)
- Hung Manh Nguyen
- Stazione Zoologica Anton Dohrn, Villa Comunale, Napoli, 80121, Italy
| | - Peter J Ralph
- Faculty of Science, Climate Change Cluster (C3), University of Technology Sydney, Sydney, NSW, 2007, Australia
| | - Lázaro Marín-Guirao
- Stazione Zoologica Anton Dohrn, Villa Comunale, Napoli, 80121, Italy.,Seagrass Ecology Group, Oceanographic Centre of Murcia, Spanish Institute of Oceanography, C/Varadero, San Pedro del Pinatar, Murcia, 30740, Spain
| | - Mathieu Pernice
- Faculty of Science, Climate Change Cluster (C3), University of Technology Sydney, Sydney, NSW, 2007, Australia
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16
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Ani CJ, Robson B. Responses of marine ecosystems to climate change impacts and their treatment in biogeochemical ecosystem models. MARINE POLLUTION BULLETIN 2021; 166:112223. [PMID: 33730556 DOI: 10.1016/j.marpolbul.2021.112223] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 02/18/2021] [Accepted: 02/25/2021] [Indexed: 06/12/2023]
Abstract
To predict the effects of climate change on marine ecosystems and the effectiveness of intervention and mitigation strategies, we need reliable marine ecosystem response models such as biogeochemical models that reproduce climate change effects. We reviewed marine ecosystem parameters and processes that are modified by climate change and examined their representations in biogeochemical ecosystem models. The interactions among important aspects of marine ecosystem modelling are not often considered due to complexity: these include the use of multiple IPCC scenarios, ensemble modelling approach, independent calibration datasets, the consideration of changes in cloud cover, ocean currents, wind speed, sea-level rise, storm frequency, storm intensity, and the incorporation of species adaptation to changing environmental conditions. Including our recommendations in future marine modelling studies could help improve the accuracy and reliability of model predictions of climate change impacts on marine ecosystems.
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Affiliation(s)
- Chinenye J Ani
- College of Science and Engineering, James Cook University, Townsville, QLD 4811, Australia; Australian Institute of Marine Science, Townsville, PMB3, Townsville, QLD 4810, Australia; AIMS@JCU, Australian Institute of Marine Science, College of Science and Engineering, James Cook University, Townsville, QLD, 4811, Australia.
| | - Barbara Robson
- Australian Institute of Marine Science, Townsville, PMB3, Townsville, QLD 4810, Australia
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17
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Pierangelini M, Thiry M, Cardol P. Different levels of energetic coupling between photosynthesis and respiration do not determine the occurrence of adaptive responses of Symbiodiniaceae to global warming. THE NEW PHYTOLOGIST 2020; 228:855-868. [PMID: 32535971 PMCID: PMC7590187 DOI: 10.1111/nph.16738] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Accepted: 05/30/2020] [Indexed: 05/06/2023]
Abstract
Disentangling the metabolic functioning of corals' endosymbionts (Symbiodiniaceae) is relevant to understanding the response of coral reefs to warming oceans. In this work, we first question whether there is an energetic coupling between photosynthesis and respiration in Symbiodiniaceae (Symbiodinium, Durusdinium and Effrenium), and second, how different levels of energetic coupling will affect their adaptive responses to global warming. Coupling between photosynthesis and respiration was established by determining the variation of metabolic rates during thermal response curves, and how inhibition of respiration affects photosynthesis. Adaptive (irreversible) responses were studied by exposing two Symbiodinium species with different levels of photosynthesis-respiration interaction to high temperature conditions (32°C) for 1 yr. We found that some Symbiodiniaceae have a high level of energetic coupling; that is, photosynthesis and respiration have the same temperature dependency, and photosynthesis is negatively affected when respiration is inhibited. Conversely, photosynthesis and respiration are not coupled in other species. In any case, prolonged exposure to high temperature caused adjustments in both photosynthesis and respiration, but these changes were fully reversible. We conclude that energetic coupling between photosynthesis and respiration exhibits wide variation amongst Symbiodiniaceae and does not determine the occurrence of adaptive responses in Symbiodiniaceae to temperature increase.
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Affiliation(s)
- Mattia Pierangelini
- Génétique et Physiologie des MicroalguesInBioS/PhytosystemsInstitut de BotaniqueUniversité de LiègeB22Liège4000Belgium
| | - Marc Thiry
- Unit of Cell BiologyGIGA‐NeurosciencesCHU Sart‐TilmanUniversity of LiègeLiègeB36, 4000Belgium
| | - Pierre Cardol
- Génétique et Physiologie des MicroalguesInBioS/PhytosystemsInstitut de BotaniqueUniversité de LiègeB22Liège4000Belgium
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18
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Ontoria Y, Webster C, Said N, Ruiz JM, Pérez M, Romero J, McMahon K. Positive effects of high salinity can buffer the negative effects of experimental warming on functional traits of the seagrass Halophila ovalis. MARINE POLLUTION BULLETIN 2020; 158:111404. [PMID: 32753189 DOI: 10.1016/j.marpolbul.2020.111404] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 06/21/2020] [Accepted: 06/23/2020] [Indexed: 06/11/2023]
Abstract
Coastal ecosystems, and especially estuaries, are subject to environmental fluctuations that can be amplified by anthropogenic changes. Under a future scenario of global warming, temperature and salinity are likely to be altered and the persistence of macrophyte-dominated ecosystems can be compromised, particularly native or local seagrass communities. This study examined the response of the local seagrass Halophila ovalis to the joint effect of a short-term salinity increase and a transient temperature stress, through two mesocosm experiments. Warming caused a decline in Fv/Fm, TNC content in leaves and plant growth, and increased dark respiration, revealing clear detrimental symptoms of heat stress on plant metabolism and performance. Salinity increase in isolation favoured ramet survival. However, in combination with warming, salinity had a positive effect on Gross Pmax. This suggests that increased salinities might dampen the negative effects of high temperatures, buffering, to some extent, the impact of global warming in temperate estuaries.
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Affiliation(s)
- Y Ontoria
- Department of Evolutionary Biology, Ecology and Environmental Sciences, University of Barcelona, Av. Diagonal 643, 08028 Barcelona, Spain.
| | - C Webster
- Centre for Marine Ecosystems Research, School of Science, Edith Cowan University, 270 Joondalup Drive, Joondalup, WA 6027, Australia
| | - N Said
- Centre for Marine Ecosystems Research, School of Science, Edith Cowan University, 270 Joondalup Drive, Joondalup, WA 6027, Australia
| | - J M Ruiz
- Seagrass Ecology Group, Oceanographic Center of Murcia, Spanish Institute of Oceanography, C/Varadero 1, 30740 San Pedro del Pinatar, Murcia, Spain
| | - M Pérez
- Department of Evolutionary Biology, Ecology and Environmental Sciences, University of Barcelona, Av. Diagonal 643, 08028 Barcelona, Spain
| | - J Romero
- Department of Evolutionary Biology, Ecology and Environmental Sciences, University of Barcelona, Av. Diagonal 643, 08028 Barcelona, Spain
| | - K McMahon
- Centre for Marine Ecosystems Research, School of Science, Edith Cowan University, 270 Joondalup Drive, Joondalup, WA 6027, Australia
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19
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Zang Y, Chen J, Li R, Shang S, Tang X. Genome-wide analysis of the superoxide dismutase (SOD) gene family in Zostera marina and expression profile analysis under temperature stress. PeerJ 2020; 8:e9063. [PMID: 32411532 PMCID: PMC7207209 DOI: 10.7717/peerj.9063] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 04/05/2020] [Indexed: 11/25/2022] Open
Abstract
Superoxide dismutases (SODs) serve as the first line of defense in the plant antioxidant enzyme system, and play a primary role in the removal of reactive oxygen species (ROS). However, our understanding of the functions of the SOD family in Zostera marina is limited. In this study, a systematic analysis was conducted on the characteristics of the SOD genes in Z. marina at the whole-genome level. Five SOD genes were identified, consisting of two Cu/ZnSODs, two FeSODs, and one MnSOD. Phylogenetic analysis showed that ZmSOD proteins could be divided into two major categories (Cu/ZnSODs and Fe-MnSODs). Sequence motifs, gene structure, and the 3D-modeled protein structures further supported the phylogenetic analysis, with each subgroup having similar motifs, exon-intron structures, and protein structures. Additionally, several cis-elements were identified that may respond to biotic and abiotic stresses. Transcriptome analysis revealed expression diversity of ZmSODs in various tissues. Moreover, qRT-PCR analysis showed that the expression level of most ZmSOD genes trended to decreased expression with the increase of temperature, indicating that heat stress inhibits expression of ZmSODs and may result in reduced ability of ZmSODs to scavenge ROS. Our results provide a basis for further functional research on the SOD gene family in Z. marina, which will help to determine the molecular mechanism of ZmSOD genes in response to environmental stress.
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Affiliation(s)
- Yu Zang
- College of Marine Life Sciences, Ocean University of China, Qingdao, China.,Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | - Jun Chen
- College of Marine Life Sciences, Ocean University of China, Qingdao, China.,Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | - Ruoxi Li
- School of Life Science, Southwest University, Chongqing, China
| | - Shuai Shang
- College of Biological and Environmental Engineering, Binzhou University, Binzhou, China
| | - Xuexi Tang
- College of Marine Life Sciences, Ocean University of China, Qingdao, China.,Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
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20
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A Comparative Assessment of Ensemble-Based Machine Learning and Maximum Likelihood Methods for Mapping Seagrass Using Sentinel-2 Imagery in Tauranga Harbor, New Zealand. REMOTE SENSING 2020. [DOI: 10.3390/rs12030355] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Seagrass has been acknowledged as a productive blue carbon ecosystem that is in significant decline across much of the world. A first step toward conservation is the mapping and monitoring of extant seagrass meadows. Several methods are currently in use, but mapping the resource from satellite images using machine learning is not widely applied, despite its successful use in various comparable applications. This research aimed to develop a novel approach for seagrass monitoring using state-of-the-art machine learning with data from Sentinel–2 imagery. We used Tauranga Harbor, New Zealand as a validation site for which extensive ground truth data are available to compare ensemble machine learning methods involving random forests (RF), rotation forests (RoF), and canonical correlation forests (CCF) with the more traditional maximum likelihood classifier (MLC) technique. Using a group of validation metrics including F1, precision, recall, accuracy, and the McNemar test, our results indicated that machine learning techniques outperformed the MLC with RoF as the best performer (F1 scores ranging from 0.75–0.91 for sparse and dense seagrass meadows, respectively). Our study is the first comparison of various ensemble-based methods for seagrass mapping of which we are aware, and promises to be an effective approach to enhance the accuracy of seagrass monitoring.
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21
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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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22
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Unsworth RKF, McKenzie LJ, Collier CJ, Cullen-Unsworth LC, Duarte CM, Eklöf JS, Jarvis JC, Jones BL, Nordlund LM. Global challenges for seagrass conservation. AMBIO 2019; 48:801-815. [PMID: 30456457 PMCID: PMC6541581 DOI: 10.1007/s13280-018-1115-y] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2018] [Revised: 10/18/2018] [Accepted: 10/23/2018] [Indexed: 05/21/2023]
Abstract
Seagrasses, flowering marine plants that form underwater meadows, play a significant global role in supporting food security, mitigating climate change and supporting biodiversity. Although progress is being made to conserve seagrass meadows in select areas, most meadows remain under significant pressure resulting in a decline in meadow condition and loss of function. Effective management strategies need to be implemented to reverse seagrass loss and enhance their fundamental role in coastal ocean habitats. Here we propose that seagrass meadows globally face a series of significant common challenges that must be addressed from a multifaceted and interdisciplinary perspective in order to achieve global conservation of seagrass meadows. The six main global challenges to seagrass conservation are (1) a lack of awareness of what seagrasses are and a limited societal recognition of the importance of seagrasses in coastal systems; (2) the status of many seagrass meadows are unknown, and up-to-date information on status and condition is essential; (3) understanding threatening activities at local scales is required to target management actions accordingly; (4) expanding our understanding of interactions between the socio-economic and ecological elements of seagrass systems is essential to balance the needs of people and the planet; (5) seagrass research should be expanded to generate scientific inquiries that support conservation actions; (6) increased understanding of the linkages between seagrass and climate change is required to adapt conservation accordingly. We also explicitly outline a series of proposed policy actions that will enable the scientific and conservation community to rise to these challenges. We urge the seagrass conservation community to engage stakeholders from local resource users to international policy-makers to address the challenges outlined here, in order to secure the future of the world's seagrass ecosystems and maintain the vital services which they supply.
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Affiliation(s)
- Richard K. F. Unsworth
- Seagrass Ecosystem Research Group, College of Science, Swansea University, Wallace Building, Swansea, SA2 8PP UK
- Project Seagrass, 33 Park Place, Cardiff, CF10 3BA UK
| | - Len J. McKenzie
- Centre for Tropical Water & Aquatic Ecosystem Research, James Cook University, Cairns, Australia
| | - Catherine J. Collier
- Centre for Tropical Water & Aquatic Ecosystem Research, James Cook University, Cairns, Australia
| | - Leanne C. Cullen-Unsworth
- Project Seagrass, 33 Park Place, Cardiff, CF10 3BA UK
- Sustainable Places Research Institute, Cardiff University, 33 Park Place, Cardiff, CF10 3BA UK
| | - Carlos M. Duarte
- Red Sea Research Center (RSRC), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900 Saudi Arabia
| | - Johan S. Eklöf
- Department of Ecology, Environment and Plant Sciences, Stockholm University, 106 91 Stockholm, Sweden
| | - Jessie C. Jarvis
- Department of Biology & Marine Biology, Center for Marine Science, University of North Carolina Wilmington, 601 South College Rd, Wilmington, NC 28403 USA
| | - Benjamin L. Jones
- Project Seagrass, 33 Park Place, Cardiff, CF10 3BA UK
- Sustainable Places Research Institute, Cardiff University, 33 Park Place, Cardiff, CF10 3BA UK
| | - Lina M. Nordlund
- Natural Resources and Sustainable Development, NRHU Department of Earth Sciences, Uppsala University, Campus Gotland, Sweden
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23
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Pierangelini M, Glaser K, Mikhailyuk T, Karsten U, Holzinger A. Light and Dehydration but Not Temperature Drive Photosynthetic Adaptations of Basal Streptophytes (Hormidiella, Streptosarcina and Streptofilum) Living in Terrestrial Habitats. MICROBIAL ECOLOGY 2019; 77:380-393. [PMID: 29974184 PMCID: PMC6394494 DOI: 10.1007/s00248-018-1225-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 06/24/2018] [Indexed: 05/05/2023]
Abstract
Streptophyte algae are the ancestors of land plants, and several classes contain taxa that are adapted to an aero-terrestrial lifestyle. In this study, four basal terrestrial streptophytes from the class Klebsormidiophyceae, including Hormidiella parvula; two species of the newly described genus Streptosarcina (S. costaricana and S. arenaria); and the newly described Streptofilum capillatum were investigated for their responses to radiation, desiccation and temperature stress conditions. All the strains showed low-light adaptation (Ik < 70 μmol photons m-2 s-1) but differed in photoprotective capacities (such as non-photochemical quenching). Acclimation to enhanced photon fluence rates (160 μmol photons m-2 s-1) increased photosynthetic performance in H. parvula and S. costaricana but not in S. arenaria, showing that low-light adaptation is a constitutive trait for S. arenaria. This lower-light adaptation of S. arenaria was coupled with a higher desiccation tolerance, providing further evidence that dehydration is a selective force shaping species occurrence in low light. For protection against ultraviolet radiation, all species synthesised and accumulated different amounts of mycosporine-like amino acids (MAAs). Biochemically, MAAs synthesised by Hormidiella and Streptosarcina were similar to MAAs from closely related Klebsormidium spp. but differed in retention time and spectral characteristics in S. capillatum. Unlike the different radiation and dehydration tolerances, Hormidiella, Streptosarcina and Streptofilum displayed preferences for similar thermal conditions. These species showed a temperature dependence of photosynthesis similar to respiration, contrasting with Klebsormidium spp. and highlighting an interspecific diversity in thermal requirements, which could regulate species distributions under temperature changes.
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Affiliation(s)
- Mattia Pierangelini
- Department of Botany, Functional Plant Biology, University of Innsbruck, 6020, Innsbruck, Austria
- Laboratoire de Génétique et Physiologie des microalgues, InBioS/Phytosystems, Institut de Botanique, Université de Liège, Liege, 4000, Belgium
| | - Karin Glaser
- Applied Ecology and Phycology, Institute of Biological Sciences, University of Rostock, Albert-Einstein-Strasse 3, 18059, Rostock, Germany
| | - Tatiana Mikhailyuk
- M.G. Kholodny Institute of Botany, National Academy of Sciences of Ukraine, Tereschenkivska Str. 2, Kyiv, 01004, Ukraine
| | - Ulf Karsten
- Applied Ecology and Phycology, Institute of Biological Sciences, University of Rostock, Albert-Einstein-Strasse 3, 18059, Rostock, Germany
| | - Andreas Holzinger
- Department of Botany, Functional Plant Biology, University of Innsbruck, 6020, Innsbruck, Austria.
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24
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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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25
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Campbell ML, Heppenstall LD, Hendry R, Martin R, Sørensen S, Rubenstein AN, Hewitt CL. Niche partitioning of intertidal seagrasses: evidence of the influence of substrate temperature. THE NEW PHYTOLOGIST 2018; 217:1449-1462. [PMID: 29238982 DOI: 10.1111/nph.14944] [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: 08/15/2017] [Accepted: 11/09/2017] [Indexed: 06/07/2023]
Abstract
The influence of soil temperature on rhizome depths of four intertidal seagrass species was investigated in central Queensland, Australia. We postulated that certain intertidal seagrass species are soil temperature-sensitive and vertically stratify rhizome depths. Below-ground vertical stratification of intertidal seagrass rhizome depths was analysed based upon microclimate (soil temperature) and microhabitat (soil type). Soil temperature profiles exhibited heat transfer from surface layers to depth that varied by microhabitat, with vertical stratification of rhizome depths between species. Halodule uninervis rhizomes maintain a narrow median soil temperature envelope; compensating for high surface temperatures by occupying deeper, cooler soil substrates. Halophila decipiens, Halophila ovalis and Zostera muelleri rhizomes are shallow-rooted and exposed to fluctuating temperatures, with broader median temperature envelopes. Halodule uninervis appears to be a niche specialist, with the two Halophila species considered as generalist niche usage species. The implications of niche use based upon soil temperature profiles and rhizome rooting depths are discussed in the context of species' thermal tolerances and below-ground biomass O2 demand associated with respiration and maintenance of oxic microshields. This preliminary evidence suggests that soil temperature interaction with rhizome rooting depths may be a factor that influences the distribution of intertidal seagrasses.
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Affiliation(s)
- Marnie L Campbell
- The Environmental Research Institute, University of Waikato, Private Bag 3105, Hamilton, 3240, New Zealand
- School of Medical and Applied Science, Central Queensland University, Bryan Jordan Drive, Gladstone, Qld, 4680, Australia
| | - Lara D Heppenstall
- The Environmental Research Institute, University of Waikato, Private Bag 3105, Hamilton, 3240, New Zealand
| | - Rebecca Hendry
- School of Medical and Applied Science, Central Queensland University, Bryan Jordan Drive, Gladstone, Qld, 4680, Australia
| | - Ross Martin
- The Environmental Research Institute, University of Waikato, Private Bag 3105, Hamilton, 3240, New Zealand
- School of Science, University of Waikato, Private Bag 3105, Hamilton, 3240, New Zealand
| | - Stine Sørensen
- The Environmental Research Institute, University of Waikato, Private Bag 3105, Hamilton, 3240, New Zealand
- School of Science, University of Waikato, Private Bag 3105, Hamilton, 3240, New Zealand
| | - Ashley N Rubenstein
- The Environmental Research Institute, University of Waikato, Private Bag 3105, Hamilton, 3240, New Zealand
- School of Science, University of Waikato, Private Bag 3105, Hamilton, 3240, New Zealand
| | - Chad L Hewitt
- The Environmental Research Institute, University of Waikato, Private Bag 3105, Hamilton, 3240, New Zealand
- School of Science, University of Waikato, Private Bag 3105, Hamilton, 3240, New Zealand
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