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Santillán-Sarmiento A, Pazzaglia J, Ruocco M, Dattolo E, Ambrosino L, Winters G, Marin-Guirao L, Procaccini G. Gene co-expression network analysis for the selection of candidate early warning indicators of heat and nutrient stress in Posidonia oceanica. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 877:162517. [PMID: 36868282 DOI: 10.1016/j.scitotenv.2023.162517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 02/01/2023] [Accepted: 02/24/2023] [Indexed: 05/06/2023]
Abstract
The continuous worldwide seagrasses decline calls for immediate actions in order to preserve this precious marine ecosystem. The main stressors that have been linked with decline in seagrasses are 1) the increasing ocean temperature due to climate change and 2) the continuous inputs of nutrients (eutrophication) associated with coastal human activities. To avoid the loss of seagrass populations, an "early warning" system is needed. We used Weighed Gene Co-expression Network Analysis (WGCNA), a systems biology approach, to identify potential candidate genes that can provide an early warning signal of stress in the Mediterranean iconic seagrass Posidonia oceanica, anticipating plant mortality. Plants were collected from both eutrophic (EU) and oligotrophic (OL) environments and were exposed to thermal and nutrient stress in a dedicated mesocosm. By correlating the whole-genome gene expression after 2-weeks exposure with the shoot survival percentage after 5-weeks exposure to stressors, we were able to identify several transcripts that indicated an early activation of several biological processes (BP) including: protein metabolic process, RNA metabolic process, organonitrogen compound biosynthetic process, catabolic process and response to stimulus, which were shared among OL and EU plants and among leaf and shoot apical meristem (SAM), in response to excessive heat and nutrients. Our results suggest a more dynamic and specific response of the SAM compared to the leaf, especially the SAM from plants coming from a stressful environment appeared more dynamic than the SAM from a pristine environment. A vast list of potential molecular markers is also provided that can be used as targets to assess field samples.
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Affiliation(s)
| | - Jessica Pazzaglia
- Department of Integrative Marine Ecology, Stazione Zoologica Anton Dohrn, 80121 Naples, Italy; Department of Life Sciences, University of Trieste, Trieste, Italy
| | - Miriam Ruocco
- Department of Integrative Marine Ecology, Stazione Zoologica Anton Dohrn, 80121 Naples, Italy
| | - Emanuela Dattolo
- Department of Integrative Marine Ecology, Stazione Zoologica Anton Dohrn, 80121 Naples, Italy
| | - Luca Ambrosino
- Research Infrastructure for Marine Biological Resources Department, Stazione Zoologica Anton Dohrn, 80121 Naples, Italy
| | - Gidon Winters
- Dead Sea and Arava Science Center (DSASC), Masada National Park, Mount Masada 8698000, Israel.; Eilat Campus, Ben-Gurion University of the Negev, Hatmarim Blv, Eilat 8855630, Israel
| | - Lázaro Marin-Guirao
- Department of Integrative Marine Ecology, Stazione Zoologica Anton Dohrn, 80121 Naples, Italy; Seagrass Ecology Group, Oceanographic Center of Murcia, Spanish Institute of Oceanography (IEO-CSIC), Murcia, Spain
| | - Gabriele Procaccini
- Department of Integrative Marine Ecology, Stazione Zoologica Anton Dohrn, 80121 Naples, Italy.
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Gallo E, Oprandi A, Bianchi CN, Morri C, Azzola A, Montefalcone M. Unexpected slow recovery of seagrass leaf epiphytes after the impact of a summer heat wave and concomitant mucilage bloom. MARINE ENVIRONMENTAL RESEARCH 2023; 189:106034. [PMID: 37290233 DOI: 10.1016/j.marenvres.2023.106034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 05/20/2023] [Accepted: 05/23/2023] [Indexed: 06/10/2023]
Abstract
The epiphytes of seagrass leaves constitute a peculiar community, comprised of a number of species specialized for this living substrate. Several studies report on the response of epiphytes to different pressures but no information exists about the effects of summer heatwaves, which have become frequent events in the last decades. This paper represents the first attempt to investigate the change in the leaf epiphyte community of the Mediterranean seagrass Posidonia oceanica due to the heatwave occurred in summer 2003. Thanks to a series of data collected seasonally between 2002 and 2006, and punctual data in the summers of 2014 and 2019, we assessed the change over time in the leaf epiphyte community. Temperature data trends were analysed through linear regression, while multivariate analyses (i.e., nMDS and SIMPER) were applied to cover data in order to assess changes over time in the epiphyte community. As a whole, the two most abundant taxa were the crustose coralline alga Hydrolithon and the encrusting bryozoan Electra posidoniae, which displayed the highest average cover values in summer (around 19%) and spring (around 9%), respectively. Epiphytes proved to be sensitive to temperature highs, displaying different effects on cover, biomass, diversity and community composition. Cover and biomass exhibited a dramatic reduction (more than 60%) after the disturbance. In particular, Hydrolithon more than halved, while E. posidoniae dropped sevenfold during summer 2003. While the former recovered comparatively quickly, the latter, as well as the whole community composition, apparently required 16 years to return to a condition similar to that of 2002.
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Affiliation(s)
- Elena Gallo
- SEL (Seascape Ecology Laboratory), DiSTAV (Department of Earth, Environmental and Life Sciences), University of Genoa, Corso Europa 26, I-16132, Genova, Italy
| | - Alice Oprandi
- SEL (Seascape Ecology Laboratory), DiSTAV (Department of Earth, Environmental and Life Sciences), University of Genoa, Corso Europa 26, I-16132, Genova, Italy.
| | - Carlo Nike Bianchi
- SEL (Seascape Ecology Laboratory), DiSTAV (Department of Earth, Environmental and Life Sciences), University of Genoa, Corso Europa 26, I-16132, Genova, Italy; Department of Integrative Marine Ecology (EMI), Stazione Zoologica Anton Dohrn - National Institute of Marine Biology, Ecology and Biotechnology, Genoa Marine Centre (GMC), Villa del Principe, Piazza Principe 4, I-16126, Genova, Italy
| | - Carla Morri
- SEL (Seascape Ecology Laboratory), DiSTAV (Department of Earth, Environmental and Life Sciences), University of Genoa, Corso Europa 26, I-16132, Genova, Italy; Department of Integrative Marine Ecology (EMI), Stazione Zoologica Anton Dohrn - National Institute of Marine Biology, Ecology and Biotechnology, Genoa Marine Centre (GMC), Villa del Principe, Piazza Principe 4, I-16126, Genova, Italy
| | - Annalisa Azzola
- SEL (Seascape Ecology Laboratory), DiSTAV (Department of Earth, Environmental and Life Sciences), University of Genoa, Corso Europa 26, I-16132, Genova, Italy; NBFC, National Biodiversity Future Center, I-90133, Palermo, Italy
| | - Monica Montefalcone
- SEL (Seascape Ecology Laboratory), DiSTAV (Department of Earth, Environmental and Life Sciences), University of Genoa, Corso Europa 26, I-16132, Genova, Italy; NBFC, National Biodiversity Future Center, I-90133, Palermo, Italy
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Maberly SC, Stott A, Gontero B. The differential ability of two species of seagrass to use carbon dioxide and bicarbonate and their modelled response to rising concentrations of inorganic carbon. FRONTIERS IN PLANT SCIENCE 2022; 13:936716. [PMID: 36388529 PMCID: PMC9648567 DOI: 10.3389/fpls.2022.936716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Accepted: 09/14/2022] [Indexed: 06/16/2023]
Abstract
Seagrass meadows are one of the most productive ecosystems on the planet, but their photosynthesis rate may be limited by carbon dioxide but mitigated by exploiting the high concentration of bicarbonate in the ocean using different active processes. Seagrasses are declining worldwide at an accelerating rate because of numerous anthropogenic pressures. However, rising ocean concentrations of dissolved inorganic carbon, caused by increases in atmospheric carbon dioxide, may benefit seagrass photosynthesis. Here we compare the ability of two seagrass from the Mediterranean Sea, Posidonia oceanica (L.) Delile and Zostera marina L., to use carbon dioxide and bicarbonate at light saturation, and model how increasing concentrations of inorganic carbon affect their photosynthesis rate. pH-drift measurements confirmed that both species were able to use bicarbonate in addition to carbon dioxide, but that Z. marina was more effective than P. oceanica. Kinetic experiments showed that, compared to Z. marina, P. oceanica had a seven-fold higher affinity for carbon dioxide and a 1.6-fold higher affinity for bicarbonate. However, the maximal rate of bicarbonate uptake in Z. marina was 2.1-fold higher than in P. oceanica. In equilibrium with 410 ppm carbon dioxide in the atmosphere, the modelled rates of photosynthesis by Z. marina were slightly higher than P. oceanica, less carbon limited and depended on bicarbonate to a greater extent. This greater reliance by Z. marina is consistent with its less depleted 13C content compared to P. oceanica. Modelled photosynthesis suggests that both species would depend on bicarbonate alone at an atmospheric carbon dioxide partial pressure of 280 ppm. P. oceanica was projected to benefit more than Z. marina with increasing atmospheric carbon dioxide partial pressures, and at the highest carbon dioxide scenario of 1135 ppm, would have higher rates of photosynthesis and be more saturated by inorganic carbon than Z. marina. In both species, the proportional reliance on bicarbonate declined markedly as carbon dioxide concentrations increased and in P. oceanica carbon dioxide would become the major source of inorganic carbon.
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Affiliation(s)
| | - Andrew W. Stott
- UK Centre for Ecology & Hydrology, Lancaster Environment Centre, Lancaster, United Kingdom
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Helber SB, Winters G, Stuhr M, Belshe EF, Bröhl S, Schmid M, Reuter H, Teichberg M. Nutrient History Affects the Response and Resilience of the Tropical Seagrass Halophila stipulacea to Further Enrichment in Its Native Habitat. FRONTIERS IN PLANT SCIENCE 2021; 12:678341. [PMID: 34421939 PMCID: PMC8374242 DOI: 10.3389/fpls.2021.678341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 07/12/2021] [Indexed: 06/13/2023]
Abstract
Eutrophication is one of the main threats to seagrass meadows, but there is limited knowledge on the interactive effects of nutrients under a changing climate, particularly for tropical seagrass species. This study aimed to detect the onset of stress in the tropical seagrass, Halophila stipulacea, by investigating the effect of in situ nutrient addition during an unusually warm summer over a 6-month period. We measured a suite of different morphological and biochemical community metrics and individual plant traits from two different sites with contrasting levels of eutrophication history before and after in situ fertilization in the Gulf of Aqaba. Nutrient stress combined with summer temperatures that surpassed the threshold for optimal growth negatively affected seagrass plants from South Beach (SB), an oligotrophic marine protected area, while H. stipulacea populations from North Beach (NB), a eutrophic and anthropogenically impacted area, benefited from the additional nutrient input. Lower aboveground (AG) and belowground (BG) biomass, reduced Leaf Area Index (LAI), smaller internodal distances, high sexual reproductive effort and the increasing occurrence of apical shoots in seagrasses from SB sites indicated that the plants were under stress and not growing under optimal conditions. Moreover, AG and BG biomass and internodal distances decreased further with the addition of fertilizer in SB sites. Results presented here highlight the fact that H. stipulacea is one of the most tolerant and plastic seagrass species. Our study further demonstrates that the effects of fertilization differ significantly between meadows that are growing exposed to different levels of anthropogenic pressures. Thus, the meadow's "history" affects it resilience and response to further stress. Our results suggest that monitoring efforts on H. stipulacea populations in its native range should focus especially on carbohydrate reserves in leaves and rhizomes, LAI, internodal length and percentage of apical shoots as suitable warning indicators for nutrient stress in this seagrass species to minimize future impacts on these valuable ecosystems.
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Affiliation(s)
- Stephanie B. Helber
- Leibniz Centre for Tropical Marine Research (ZMT) GmbH, Bremen, Germany
- Institute for Chemistry and Biology of the Marine Environment (ICBM), Oldenburg, Germany
| | - Gidon Winters
- The Dead Sea and Arava Science Center (ADSSC), Jerusalem, Israel
- Ben-Gurion University of the Negev, Eilat, Israel
| | - Marleen Stuhr
- Tropical Coral Ecophysiology, Interuniversity Institute for Marine Sciences - Eilat (IUI), Eilat, Israel
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University (BIU), Ramat Gan, Israel
| | - E. F. Belshe
- Leibniz Centre for Tropical Marine Research (ZMT) GmbH, Bremen, Germany
| | - Stefanie Bröhl
- Leibniz Centre for Tropical Marine Research (ZMT) GmbH, Bremen, Germany
| | - Michael Schmid
- Leibniz Centre for Tropical Marine Research (ZMT) GmbH, Bremen, Germany
| | - Hauke Reuter
- Leibniz Centre for Tropical Marine Research (ZMT) GmbH, Bremen, Germany
- Faculty for Biology and Chemistry, University of Bremen, Bremen, Germany
| | - Mirta Teichberg
- Leibniz Centre for Tropical Marine Research (ZMT) GmbH, Bremen, Germany
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