ORCID Profile
0000-0003-3968-2718
Current Organisations
King Abdullah University of Science and Technology (KAUST)
,
Université Pierre et Marie Curie
,
Université de Bordeaux
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Publications
Accumulation of Carbonates Contributes to Coastal Vegetated Ecosystems Keeping Pace With Sea Level Rise in an Arid Region (Arabian Peninsula)
Publisher: American Geophysical Union (AGU)
Date: 05-2018
DOI: 10.1029/2017JG004288
Characterization of the CO 2 system in a coral reef, a seagrass meadow and a mangrove forest in the central Red Sea
Publisher: American Geophysical Union (AGU)
Date: 11-2019
DOI: 10.1029/2019JC015266
Carbon dioxide and methane fluxes at the air–sea interface of Red Sea mangroves
Publisher: Copernicus GmbH
Date: 04-09-2018
Abstract: Abstract. Mangrove forests are highly productive tropical and subtropical coastal systems that provide a variety of ecosystem services, including the sequestration of carbon. While mangroves are reported to be the most intense carbon sinks among all forests, they can also support large emissions of greenhouse gases (GHGs), such as carbon dioxide (CO2) and methane (CH4), to the atmosphere. However, data derived from arid mangrove systems like the Red Sea are lacking. Here, we report net emission rates of CO2 and CH4 from mangroves along the eastern coast of the Red Sea and assess the relative role of these two gases in supporting total GHG emissions to the atmosphere. Diel CO2 and CH4 emission rates ranged from −3452 to 7500 µmol CO2 m−2 d−1 and from 0.9 to 13.3 µmol CH4 m−2 d−1 respectively. The rates reported here fall within previously reported ranges for both CO2 and CH4, but maximum CO2 and CH4 flux rates in the Red Sea are 10- to 100-fold below those previously reported for mangroves elsewhere. Based on the isotopic composition of the CO2 and CH4 produced, we identified potential origins of the organic matter that support GHG emissions. In all but one mangrove stand, GHG emissions appear to be supported by organic matter from mixed sources, potentially reducing CO2 fluxes and instead enhancing CH4 production, a finding that highlights the importance of determining the origin of organic matter in GHG emissions. Methane was the main source of CO2 equivalents despite the comparatively low emission rates in most of the s led mangroves and therefore deserves careful monitoring in this region. By further resolving GHG fluxes in arid mangroves, we will better ascertain the role of these forests in global carbon budgets.
High Summer Temperatures Amplify Functional Differences Between Coral‐ and Algae‐Dominated Reef Communities
Publisher: Wiley
Date: 2021
DOI: 10.1002/BES2.1822
Crustose coralline algae can contribute more than corals to coral reef carbonate production
Publisher: Springer Science and Business Media LLC
Date: 06-04-2023
DOI: 10.1038/S43247-023-00766-W
Abstract: Understanding the drivers of net coral reef calcium carbonate production is increasingly important as ocean warming, acidification, and other anthropogenic stressors threaten the maintenance of coral reef structures and the services these ecosystems provide. Despite intense research effort on coral reef calcium carbonate production, the inclusion of a key reef forming/accreting calcifying group, the crustose coralline algae, remains challenging both from a theoretical and practical standpoint. While corals are typically the primary reef builders of contemporary reefs, crustose coralline algae can contribute equally. Here, we combine several sets of data with numerical and theoretical modelling to demonstrate that crustose coralline algae carbonate production can match or even exceed the contribution of corals to reef carbonate production. Despite their importance, crustose coralline algae are often inaccurately recorded in benthic surveys or even entirely missing from coral reef carbonate budgets. We outline several recommendations to improve the inclusion of crustose coralline algae into such carbonate budgets under the ongoing climate crisis.
Increasing importance of crustose coralline algae to coral reef carbonate production under ongoing climate change
Publisher: Research Square Platform LLC
Date: 06-12-2022
DOI: 10.21203/RS.3.RS-2327274/V1
Abstract: Understanding the drivers of net coral reef calcium carbonate production is increasingly important as ocean warming, acidification, and other anthropogenic stressors threaten the maintenance of coral reef structures and the services these ecosystems provide. Despite intense research effort on coral reef calcium carbonate production, the inclusion of a key reef forming/accreting calcifying group, the crustose coralline algae (CCA), remains challenging both from a theoretical and practical standpoint. While corals are typically the primary reef builders of today, ongoing declines in coral cover due to a range of environmental perturbations will likely increase the relative importance of CCA and other non-scleractinian calcifying taxa to coral reef carbonate production. Here, we demonstrate that CCA are important carbonate producers that, under certain conditions, can match or even exceed the contribution of corals to coral reef carbonate production. Despite their importance, CCA are often inaccurately recorded in benthic surveys or even entirely missing from coral reef carbonate budgets. We outline several recommendations to improve the inclusion of CCA into such carbonate budgets under the ongoing climate crisis.
Anomalies in the Carbonate System of Red Sea Coastal Habitats
Publisher: Copernicus GmbH
Date: 03-06-2019
DOI: 10.5194/BG-2019-200
Integrating environmental variability to broaden the research on coral responses to future ocean conditions
Publisher: Wiley
Date: 03-09-2021
DOI: 10.1111/GCB.15840
Abstract: Our understanding of the response of reef‐building corals to changes in their physical environment is largely based on laboratory experiments, analysis of long‐term field data, and model projections. Experimental data provide unique insights into how organisms respond to variation of environmental drivers. However, an assessment of how well experimental conditions cover the breadth of environmental conditions and variability where corals live successfully is missing. Here, we compiled and analyzed a globally distributed dataset of in‐situ seasonal and diurnal variability of key environmental drivers (temperature, p CO 2 , and O 2 ) critical for the growth and livelihood of reef‐building corals. Using a meta‐analysis approach, we compared the variability of environmental conditions assayed in coral experimental studies to current and projected conditions in their natural habitats. We found that annual temperature profiles projected for the end of the 21st century were characterized by distributional shifts in temperatures with warmer winters and longer warm periods in the summer, not just peak temperatures. Furthermore, short‐term hourly fluctuations of temperature and p CO 2 may regularly expose corals to conditions beyond the projected average increases for the end of the 21st century. Coral reef sites varied in the degree of coupling between temperature, p CO 2 , and dissolved O 2 , which warrants site‐specific, differentiated experimental approaches depending on the local hydrography and influence of biological processes on the carbonate system and O 2 availability. Our analysis highlights that a large portion of the natural environmental variability at short and long timescales is underexplored in experimental designs, which may provide a path to extend our understanding on the response of corals to global climate change.
Variable response of Red Sea coral communities to recent disturbance events along a latitudinal gradient
Publisher: Springer Science and Business Media LLC
Date: 11-11-2021
Investing in Blue Natural Capital to Secure a Future for the Red Sea Ecosystems
Publisher: Frontiers Media SA
Date: 15-01-2021
DOI: 10.3389/FMARS.2020.603722
Abstract: For millennia, coastal and marine ecosystems have adapted and flourished in the Red Sea’s unique environment. Surrounded by deserts on all sides, the Red Sea is subjected to high dust inputs and receives very little freshwater input, and so harbors a high salinity. Coral reefs, seagrass meadows, and mangroves flourish in this environment and provide socio-economic and environmental benefits to the bordering coastlines and countries. Interestingly, while coral reef ecosystems are currently experiencing rapid decline on a global scale, those in the Red Sea appear to be in relatively better shape. That said, they are certainly not immune to the stressors that cause degradation, such as increasing ocean temperature, acidification and pollution. In many regions, ecosystems are already severely deteriorating and are further threatened by increasing population pressure and large coastal development projects. Degradation of these marine habitats will lead to environmental costs, as well as significant economic losses. Therefore, it will result in a missed opportunity for the bordering countries to develop a sustainable blue economy and integrate innovative nature-based solutions. Recognizing that securing the Red Sea ecosystems’ future must occur in synergy with continued social and economic growth, we developed an action plan for the conservation, restoration, and growth of marine environments of the Red Sea. We then investigated the level of resources for financial and economic investment that may incentivize these activities. This study presents a set of commercially viable financial investment strategies, ecological innovations, and sustainable development opportunities, which can, if implemented strategically, help ensure long-term economic benefits while promoting environmental conservation. We make a case for investing in blue natural capital and propose a strategic development model that relies on maintaining the health of natural ecosystems to safeguard the Red Sea’s sustainable development.
Organic carbon sequestration and storage in vegetated coastal habitats along the western coast of the Arabian Gulf
Publisher: IOP Publishing
Date: 27-06-2018
A portfolio of climate‐tailored approaches to advance the design of marine protected areas in the Red Sea
Publisher: Wiley
Date: 18-06-2021
DOI: 10.1111/GCB.15719
Abstract: Intensified coastal development is compromising the health and functioning of marine ecosystems. A key ex le of this is the Red Sea, a bio ersity hotspot subjected to increasing local human pressures. While some marine‐protected areas (MPAs) were placed to alleviate these stressors, it is unclear whether these MPAs are managed or enforced, thus providing limited protection. Yet, most importantly, MPAs in the Red Sea were not designed using climate considerations, likely diminishing their effectiveness against global stressors. Here, we propose to tailor the design of MPAs in the Red Sea by integrating approaches to enhance climate change mitigation and adaptation. First, including coral bleaching susceptibility could produce a more resilient network of MPAs by safeguarding reefs from different thermal regions that vary in spatiotemporal bleaching responses, reducing the risk that all protected reefs will bleach simultaneously. Second, preserving the basin‐wide genetic connectivity patterns that are assisted by mesoscale eddies could further ensure recovery of sensitive populations and maintain species potential to adapt to environmental changes. Finally, protecting mangrove forests in the northern and southern Red Sea that act as major carbon sinks could help offset greenhouse gas emissions. If implemented with multinational cooperation and concerted effort among stakeholders, our portfolio of climate‐tailored approaches may help build a network of MPAs in the Red Sea that protects more effectively its coastal resources against escalating coastal development and climate instability. Beyond the Red Sea, we anticipate this study to serve as an ex le of how to improve the utility of tropical MPAs as climate‐informed conservation tools.
Total alkalinity production in a mangrove ecosystem reveals an overlooked Blue Carbon component
Publisher: Wiley
Date: 16-10-2020
DOI: 10.1002/LOL2.10170
Abstract: Mangroves have the capacity to sequester organic carbon (C org ) in their sediments permanently. However, the carbon budget of mangroves is also affected by the total alkalinity (TA) budget. Principally, TA emitted from carbonate sediment dissolution is a perennial sink of atmospheric CO 2 . The assessment of the TA budget of mangrove carbonate sediments in the Red Sea revealed a large TA emission of 403 ± 17 mmol m −2 d −1 , independent of light, seasons, or the presence of pneumatophores, compared to −36 ± 10 mmol m −2 d −1 in lagoon sediment. We estimate the TA emission from carbonate dissolution in Red Sea mangroves supported a CO 2 uptake of 345 ± 15 gC m −2 yr −1 , 23‐fold the C org burial rate of 15 gC m −2 yr −1 . The focus on C org burial in sediments may substantially underestimate the role of mangroves in CO 2 removal. Quantifying the role of mangroves in climate change mitigation requires carbonate dissolution to be included in assessments.
Anthropogenic-induced acceleration of elemental burial rates in blue carbon repositories of the Arabian Gulf
Publisher: Elsevier BV
Date: 06-2020
DOI: 10.1016/J.SCITOTENV.2019.135177
Abstract: Along the past century, the Arabian Gulf has experienced a continuous and fast coastal development leading to increase the human pressures on the marine environment. The present study attempts to describe the historical changes of trace elements in the sediments of vegetated coastal habitats in the western Arabian Gulf.
Exponential increase of plastic burial in mangrove sediments as a major plastic sink
Publisher: American Association for the Advancement of Science (AAAS)
Date: 30-10-2020
Abstract: Exponentially increasing burial rates of microplastics since the 1950s confirm mangrove sediments as long-term sinks.
Role of carbonate burial in Blue Carbon budgets
Publisher: Springer Science and Business Media LLC
Date: 07-03-2019
DOI: 10.1038/S41467-019-08842-6
Abstract: Calcium carbonates (CaCO 3 ) often accumulate in mangrove and seagrass sediments. As CaCO 3 production emits CO 2 , there is concern that this may partially offset the role of Blue Carbon ecosystems as CO 2 sinks through the burial of organic carbon (C org ). A global collection of data on inorganic carbon burial rates (C inorg , 12% of CaCO 3 mass) revealed global rates of 0.8 TgC inorg yr −1 and 15–62 TgC inorg yr −1 in mangrove and seagrass ecosystems, respectively. In seagrass, CaCO 3 burial may correspond to an offset of 30% of the net CO 2 sequestration. However, a mass balance assessment highlights that the C inorg burial is mainly supported by inputs from adjacent ecosystems rather than by local calcification, and that Blue Carbon ecosystems are sites of net CaCO 3 dissolution. Hence, CaCO 3 burial in Blue Carbon ecosystems contribute to seabed elevation and therefore buffers sea-level rise, without undermining their role as CO 2 sinks.
Accelerated burial of petroleum hydrocarbons in Arabian Gulf blue carbon repositories
Publisher: Elsevier BV
Date: 06-2019
DOI: 10.1016/J.SCITOTENV.2019.01.437
Abstract: Massive consumption of petroleum since the past century has led to considerable emissions into marine ecosystems. Marine sediments may accumulate substantial quantities of petroleum and associated contaminants in oil-producing areas. Here, we report accelerated accumulation of total petroleum hydrocarbons (TPH) in 'blue carbon' vegetated ecosystems of the Arabian Gulf - the world's most important region for oil production. In addition to increased accumulation with the onset of oil exploitation, sediment records reflect a large depositional event associated with the 1991 Gulf War, with the magnitude of these maxima varying across habitats, depending on their elevation along the shoreline. Blue carbon ecosystems of the Arabian Gulf currently bury about 2300 megagrams (Mg) of TPHs annually and have accumulated TPH stocks of 59,799 Mg over the past 25 years alone. Massive burial and sequestration of TPH by blue carbon ecosystems is an important, but thus far unrecognized, removal mechanism in the Arabian Gulf. Conserving these ecosystems is important to avoid possible remobilization of sequestered TPH into the surrounding environment.
Light-dependent calcification in Red Sea giant clam <i>Tridacna maxima</i>
Publisher: Copernicus GmbH
Date: 09-07-2019
Abstract: Abstract. Tropical giant clams of the subfamily Tridacninae, including the species Tridacna maxima, are unique among bivalves as they live in a symbiotic relationship with unicellular algae and generally function as net photoautotrophs. Light is therefore crucial for these species to thrive. Here we examine the light dependency of calcification rates of T. maxima in the central Red Sea as well as the patterns of its abundance with depth in the field. Red Sea T. maxima show the highest densities at a depth of 3 m with 0.82±0.21 and 0.11±0.03 in iduals m−2 (mean ± SE) at sheltered and exposed sites, respectively. Experimental assessment of net calcification (µmol CaCO3 cm−2 h−1) and gross primary production (µmol O2 cm−2 h−1) under seven light levels (1061, 959, 561, 530, 358, 244, and 197 µmol quanta m−2 s−1) showed net calcification rates to be significantly enhanced under light intensities corresponding to a water depth of 4 m (0.65±0.03 µmol CaCO3 cm−2 h−1 mean ± SE), while gross primary production was 2.06±0.24 µmol O2 cm−2 h−1 (mean ± SE). We found a quadratic relationship between net calcification and tissue dry mass (DM in gram), with clams of an intermediate size (about 15 g DM) showing the highest calcification. Our results show that the Red Sea giant clam T. maxima stands out among bivalves as a remarkable calcifier, displaying calcification rates comparable to other tropical photosymbiotic reef organisms such as corals.
Anomalies in the carbonate system of Red Sea coastal habitats
Publisher: Copernicus GmbH
Date: 29-01-2020
Abstract: Abstract. We use observations of dissolved inorganic carbon (DIC) and total alkalinity (TA) to assess the impact of ecosystem metabolic processes on coastal waters of the eastern Red Sea. A simple, single-end-member mixing model is used to account for the influence of mixing with offshore waters and evaporation–precipitation and to model ecosystem-driven perturbations on the carbonate system chemistry of coral reefs, seagrass meadows and mangrove forests. We find that (1) along-shelf changes in TA and DIC exhibit strong linear relationships that are consistent with basin-scale net calcium carbonate precipitation (2) ecosystem-driven changes in TA and DIC are larger than offshore variations in % of s led seagrass meadows and mangrove forests, changes which are influenced by a combination of longer water residence times and community metabolic rates and (3) the s led mangrove forests show strong and consistent contributions from both organic respiration and other sedimentary processes (carbonate dissolution and secondary redox processes), while seagrass meadows display more variability in the relative contributions of photosynthesis and other sedimentary processes (carbonate precipitation and oxidative processes). The results of this study highlight the importance of resolving the influences of water residence times, mixing and upstream habitats on mediating the carbonate system and coastal air–sea carbon dioxide fluxes over coastal habitats in the Red Sea.
Role of vegetated coastal ecosystems as nitrogen and phosphorous filters and sinks in the coasts of Saudi Arabia
Publisher: IOP Publishing
Date: 03-2020
Abstract: Vegetated coastal ecosystems along the Red Sea and Arabian Gulf coasts of Saudi Arabia thrive in an extremely arid and oligotrophic environment, with high seawater temperatures and salinity. Mangrove, seagrass and saltmarsh ecosystems have been shown to act as efficient sinks of sediment organic carbon, earning these vegetated ecosystems the moniker ‘blue carbon’ ecosystems. However, their role as nitrogen and phosphorus (N and P) sinks remains poorly understood. In this study, we examine the capacity of blue carbon ecosystems to trap and store nitrogen and phosphorous in their sediments in the central Red Sea and Arabian Gulf. We estimated the N and P stocks (in 0.2 m thick-sediments) and accumulation rates (for the last century based on 210 Pb and for the last millennia based on 14 C) in mangrove, seagrass and saltmarsh sediments from eight locations along the coast of Saudi Arabia (81 cores in total). The N and P stocks contained in the top 20 cm sediments ranged from 61 g N m −2 in Red Sea seagrass to 265 g N m −2 in the Gulf saltmarshes and from 70 g P m −2 in Red Sea seagrass meadows and mangroves to 58 g P m −2 in the Gulf saltmarshes. The short-term N and P accumulation rates ranged from 0.09 mg N cm −2 yr −1 in Red Sea seagrass to 0.38 mg N cm −2 yr −1 in Gulf mangrove, and from 0.027 mg P cm −2 yr −1 in the Gulf seagrass to 0.092 mg P cm −2 yr −1 in Red Sea mangroves. Short-term N and P accumulation rates were up to 10-fold higher than long-term accumulation rates, highlighting increasing sequestration of N and P over the past century, likely due to anthropogenic activities such as coastal development and wastewater inputs.
Reef accumulation is decoupled from recent degradation in the central and southern Red Sea
Publisher: Elsevier BV
Date: 02-2022
DOI: 10.1016/J.SCITOTENV.2021.151176
Abstract: Reefs are biogenic structures that result in three-dimensional accumulations of calcium carbonate. Over geological timescales, a positive balance between the production and accumulation of calcium carbonate versus erosional and off-reef transport processes maintains positive net accretion on reefs. Yet, how ecological processes occurring over decadal timescales translate to the accumulation of geological structures is poorly understood, in part due to a lack of studies with detailed time-constrained chronologies of reef accretion over decades to centuries. Here, we combined ecological surveys of living reefs with palaeoecological reconstructions and high-precision radiometric (U-Th) age-dating of fossil reefs represented in both reef sediment cores and surficial dead in situ corals, to reconstruct the history of community composition and carbonate accumulation across the central and southern Saudi Arabian Red Sea throughout the late Holocene. We found that reefs were primarily comprised of thermally tolerant massive Porites colonies, creating a consolidated coral framework, with unconsolidated branching coral rubble accumulating among massive corals on shallow (5-8 m depth) exposed (windward), and gently sloping reef slopes. These unconsolidated reef rubble fields were formed primarily from ex situ Acropora and Pocillopora coral fragments, infilled post deposition within a sedimentary matrix. Bayesian age-depth models revealed a process of punctuated deposition of post-mortem coral fragments transported from adjacent reef environments. That a large portion of Saudi Arabian Red Sea reef slopes is driven by allochthonous deposition (transportation) has important implications for modeling carbonate budgets and reef growth. In addition, a multi-decadal lag exists between the time of death for branching in situ coral and incorporation into the unconsolidated reef rubble. This indicates that recent climate related degradation in the 21st century has not had an immediately negative effect on reef building processes affecting a large portion of the reef area in the Saudi Arabian Red Sea.
Oxygen supersaturation protects coastal marine fauna from ocean warming
Publisher: American Association for the Advancement of Science (AAAS)
Date: 06-09-2019
Abstract: Hyperoxia extends heat tolerance in marine ectotherms.
Stunted Mangrove Trees in the Oligotrophic Central Red Sea Relate to Nitrogen Limitation
Publisher: Frontiers Media SA
Date: 31-07-2020
High summer temperatures amplify functional differences between coral‐ and algae‐dominated reef communities
Publisher: Wiley
Date: 27-12-2020
DOI: 10.1002/ECY.3226
Related Organisations
King Abdullah University Of Science And Technology (KAUST)
Location: Saudi Arabia
Androfert Centro De Referência De Reprodução Masculina
Location: Brazil
GEOMAR Helmholtz-Zentrum Für Ozeanforschung Kiel
Location: No location found
Koninklijk Nederlands Instituut Voor Onderzoek Der Zee
Location: Netherlands
Related Funding Activities
No related grants have been discovered for vincent saderne.