Rui Santos

Rui Santos
Universidade do Algarve | UALG · Centro de Ciências do Mar (CCMAR)

40.67
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Habilitation

About

218
Publications
44,177
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3,871
Citations
Research Experience
September 1993 - present
Universidade do Algarve
Position
  • Professor (Associate)
September 1993 - December 2012
Universidade do Algarve
Position

Publications

Publications (218)
Article
1. The impact of global warming on the metabolic state of a species may be examined by either measuring physiological rates across a latitudinal gradient or by assessing short‐term responses under experimentally controlled temperature regimes. The combination of the two approaches is seldom used but it provides valuable information on an organism’s...
Article
Marine climate change mitigation initiatives have recently attracted a great deal of interest in the role of natural carbon sinks, particularly on coastal systems. Brown seaweeds of the genus Sargassum are the largest canopy-forming algae in tropical and subtropical environments, with a wide global distribution on rocky reefs and as floating stands...
Article
We investigated the nutrient acquisition of the seagrass Cymodocea nodosa and the importance of sediment to water column nutrient pulses, which regularly occur in coastal lagoons forced by incoming flood tides. Ammonium was preferentially taken up and accounted for 60 to 90 % of the total daily N acquisition, whereas amino acid acquisition through...
Article
Despite worldwide proliferation of seaweeds of the genus Caulerpa and subsequent effects on benthic communities, little is known about the nutritional physiology of Caulerpales. Here, we investigated the uptake rates of ammonium, nitrate, amino acids and phosphate through the fronds and rhizoids + stolon, the internal translocation of nitrogen, and...
Article
Full-text available
Rhodolith (maërl) beds are biodiversity hotspots with a worldwide distribution. Maërl is the general term for free-living non-geniculate rhodoliths or coralline red algae. In southern Portugal, maërl beds are mainly composed of Phymatolithon lusitanicum, recently identified as a new species and commonly misidentified as Phymatolithon calcareum. Pho...
Article
Despite worldwide proliferation of seaweeds of the genus Caulerpa and subsequent effects on benthic communities, little is known about the nutritional physiology of Caulerpales. Here, we investigated the uptake rates of ammonium, nitrate, amino acids and phosphate through the fronds and rhizoids + stolon, the internal translocation of nitrogen, and...
Article
In his News In Depth story “Mystery oil spill threatens marine sanctuary in Brazil” (8 November 2019, p. 672), H. Escobar highlights important ecosystems that have been affected by the spill. However, he did not mention the Brazilian rhodolith beds—the most extensive, abundant, and diverse biogenic carbonate habitats in the South Atlantic. The oil...
Article
Despite the wide knowledge about prevalent effects of ocean acidification on single species, the consequences on species interactions that may promote or prevent habitat shifts are still poorly understood. Using natural CO2 vents, we investigated changes in a key tri-trophic chain embedded within all its natural complexity in seagrass systems. We f...
Article
Full-text available
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
Article
Full-text available
Posidonia oceanica is the only reported seagrass to produce significant amount of dimethylsulfoniopropionate (DMSP). It is also the largest known producer of DMSP among coastal and inter-tidal higher plants. Here we studied i) the weekly to seasonal variability and the depth variability of DMSP and its related compound dimethylsulfoxide (DMSO) in P...
Article
Seagrasses often occur around shallow marine CO2 seeps, allowing assessment of trace metal accumulation. Here, we measured Cd, Cu, Hg, Ni, Pb and Zn levels at six CO2 seeps and six reference sites in the Mediterranean. Some seep sediments had elevated metal concentrations; an extreme example was Cd which was 43x more concentrated at a seep than its...
Article
Full-text available
The concept of ecosystem services (ES) emerges as strategic to explain the influences that the ocean, and in particular coastal ecosystems, have on us and how we influence them back. Despite being a term coined several decades ago and being already wide-spread in the scientific community and among policy-makers, the ES concept still lacks recogniti...
Article
Full-text available
The combination of ocean acidification (OA) and global warming is expected to have a significant effect on the diversity and functioning of marine ecosystems, particularly on calcifying algae such as rhodoliths (maërl) that form extensive beds worldwide, from polar to tropical regions. In addition, the increasing frequency of extreme events, such a...
Article
Full-text available
The term Blue Carbon (BC) was first coined a decade ago to describe the disproportionately large contribution of coastal vegetated ecosystems to global carbon sequestration. The role of BC in climate change mitigation and adaptation has now reached international prominence. To help prioritise future research, we assembled leading experts in the fie...
Article
Full-text available
Seagrass meadows, key ecosystems supporting fisheries, carbon sequestration and coastal protection, are globally threatened. In Europe, loss and recovery of seagrasses are reported, but the changes in extent and density at the continental scale remain unclear. Here we collate assessments of changes from 1869 to 2016 and show that 1/3 of European se...
Chapter
The Portuguese coast is located in a biogeographic transition zone, between temperate and subtropical waters where the northern or southern distribution limits of many species are found. Portuguese coastline is characterized by specific hydrographical features with a cooler northern region affected by both upwelling and rainfall leading to higher v...
Article
Full-text available
Coastal vegetated ecosystems are major organic carbon (OC) and total nitrogen (TN) sinks, but the mechanisms that regulate their spatial variability need to be better understood. Here we assessed how superficial sedimentary OC and TN within intertidal vegetated assemblages (saltmarsh and seagrass) vary along a flow gradient, which is a major driver...
Article
Full-text available
Seagrasses live in highly variable light environments and adjust to these variations by expressing acclimatory responses at different plant organizational levels (meadow, shoot, leaf and chloroplast level). Yet, comparative studies, to identify species’ strategies, and integration of the relative importance of photoacclimatory adjustments at differ...
Preprint
Full-text available
Seagrasses form important habitats around shallow marine CO2 seeps, providing opportunities to assess trace element (TE) accumulation along gradients in seawater pH. Here we assessed Cd, Cu, Hg, Ni, Pb and Zn levels in sediment and seagrasses at six CO2 seeps and reference sites off Italy and Greece. Some seep sediments had much higher concentratio...
Article
Despite the importance of coastal ecosystems for the global carbon budgets, knowledge of their carbon storage capacity and the factors driving variability in storage capacity is still limited. Here we provide an estimate on the magnitude and variability of carbon stocks within a widely distributed marine foundation species throughout its distributi...
Article
Full-text available
Restoration of seagrass beds through seedlings is an alternative to the transplantation of adult plants that reduces the impact over donor areas and increases the genetic variability of restored meadows. To improve the use of Cymodocea nodosa seedlings, obtained from seeds germinated in vitro, in restoration programs, we investigated the ammonium a...
Article
Full-text available
Bacteriological and technical agars are in short supply with potential consequences for research, public health and clinical labs around the world. To diagnose bottlenecks and sustainability problems that may be putting the industry at risk, we analyzed the available time-series of Gelidium global landings, the industry raw material. Data on Gelidi...
Preprint
Rising carbon dioxide (CO2) concentrations in the atmosphere will increase the average pCO2 level in the world oceans, which will have a knock-on effect on the marine ecosystem. Coastal seagrass communities are predicted to benefit from the increase in CO2 levels, but long term effects of elevated CO2 on seagrass communities are less understood. Po...
Preprint
Submarine hydrothermal activity is of ecological interest as this can cause natural gradients in both ocean acidity and trace elements, offering opportunities to assess their combined effects. Here Fe and trace elements were analysed from sediments, roots, rhizomes and leaves of seagrass at six CO2 seeps and reference sites off Greece and Italy. Me...
Article
Full-text available
Maerl/rhodolith beds are protected habitats that may be affected by ocean acidification (OA), but it is still unclear how the availability of CO2 will affect the metabolism of these organisms. Some of the inconsistencies found among OA experimental studies may be related to experimental exposure time and synergetic effects with other stressors. Her...
Article
Full-text available
Long-distance dispersal is one of the main drivers structuring the distribution of marine biodiversity. This study reports the first occurrence of Macrocystis pyrifera and Durvillaea antarctica rafts on the southwestern warm temperate coast of the Atlantic Ocean. Our results indicate that an extreme meteo-oceanographic event, characterized by a nor...
Article
Full-text available
In-situ production responses of air-exposed intertidal communities under CO2 enrichment are reported here for the first time. We assessed the short-term effects of CO2 on the light responses of the net community production (NCP) and community respiration (CR) of intertidal Z. noltei and unvegetated sediment communities of Ria Formosa lagoon, when e...
Article
Full-text available
Seagrasses dominate shallow coastal environments where nitrogen (N) availability in the water column is often sporadic and mainly in the form of pulses. We investigated the N uptake competition between seagrasses and seaweeds through a series of ¹⁵N surge uptake experiments combining single-species and mixed incubations across ammonium concentratio...
Conference Paper
Under high irradiance, the photosynthetic activity of dense seagrass meadows saturates the water forming oxygen bubbles. The diel cycle of bubble production peaks at mid-day, following light intensity pattern. It is well known that bubbles strongly affect the acoustic propagation, increasing signal attenuation and decreasing the effective water sou...
Article
Full-text available
Here we report the first use of massive scale RNA-Sequencing to explore seagrass response to CO2 -driven ocean acidification (OA). Large-scale gene expression changes in the seagrass Cymodocea nodosa occurred at CO2 levels projected by the end of the century. C. nodosa transcriptome was obtained using Illumina RNA-Seq technology and de novo assembl...
Article
Full-text available
Seagrass meadows in São Tomé and Príncipe, eastern Atlantic Ocean, are described here for the first time. Specifically, we quantified the biomass and density of seagrasses, characterized the plant morphology and measure their nutrient content as a proxy of the nutrient environmental conditions where the meadows develop. The seagrass Halodule wright...
Article
Under high irradiance, the photosynthetic activity of dense seagrass meadows saturates the waterforming oxygen bubbles. The diel cycle of bubble production peaks at mid-day, following light intensity pattern. It is well known that bubbles strongly affect the acoustic propagation, increasing signal attenuation and decreasing the effective watersound...
Article
Full-text available
Ocean acidification (OA) predicted for 2100 is expected to shift seagrass epiphyte communities towards the dominance of more tolerant non-calcifying taxa. However, little is known about the indirect effects of such changes on food provision to key seagrass consumers. We found that epiphyte communities of the seagrass Posidonia oceanica in two natur...
Article
Full-text available
Here we present the results of a multiple organizational level analysis conceived to identify acclimative/adaptive strategies exhibited by the seagrass Posidonia oceanica to the daily fluctuations in the light environment, at contrasting depths. We assessed changes in photophysiological parameters, leaf respiration, pigments, and protein and mRNA e...
Article
Full-text available
Ocean acidification is a major threat for marine life but seagrasses are expected to benefit from high CO2. In situ (long-term) and transplanted (short-term) plant incubations of the seagrass Cymodocea nodosa were performed near and away the influence of volcanic CO2 vents at Vulcano Island to test the hypothesis of beneficial effects of CO2 on pl...
Article
Ocean acidification (OA) predicted for 2100 is expected to shift seagrass epiphyte communities towards the dominance of more tolerant non-calcifying taxa. However, little is known about the indirect effects of such changes on food provision to key seagrass consumers. We found that epiphyte communities of the seagrass Posidonia oceanica in two natur...
Article
Full-text available
Seagrass ecosystems are important natural carbon sinks but their efficiency varies greatly depending on species composition and environmental conditions. What causes this variation is not fully known and could have important implications for management and protection of the seagrass habitat to continue to act as a natural carbon sink. Here, we asse...
Data
VIP-values (variance of importance) for independent variables used in the PLS model testing relationships to carbon content. The model assesses the relative influence of different predictors on % Corg in sediment (using a mean for the top 25 cm sediment). The variables are listed in the level of importance and those with VIP-values >1 (dashed line)...
Data
Semi-log plots (log10[x+1]) for sediment density (g DW mL-1) (a), and sediment porosity (%) (b) in relation to organic carbon content (% Corg) for unvegetated areas. There was no significant relationship between sediment density and organic carbon. The sediment porosity was, however, positively linked to sedimentary organic carbon but had a low R2-...
Poster
Full-text available
Marine magnoliophytes are major primary producers in coastal benthic habitats worldwide. They play a crucial role in the global carbon cycle (one of the more efficient blue carbon wells). Hence, it is necessary to characterise the eco-systemic services seagrass meadows provide. Posidonia oceanica (L.) Delile, the main Mediterranean seagrass species...
Article
Full-text available
Most ocean acidification (OA) experimental systems rely on pH as an indirect way to control CO 2. However, accurate pH measurements are difficult to obtain and shifts in temperature and/or salinity alter the relationship between pH and pCO 2. Here we describe a system in which the target pCO 2 is controlled via direct analysis of pCO 2 in seawater....
Data
Raw data from Figs. 3–7 and Table 1.
Article
Full-text available
We conducted a study that shows that light and dark conditions do not affect the uptake rates of ammonium and nitrate by the seagrass Zostera noltei. This is an important advantage over some seaweed species in which these rates are severely reduced at night. In the light, the ammonium uptake rates were initially higher (15 and 20umol gDW h-1) and s...
Article
The seasonal and annual nitrogen (N), phosphorus (P), and carbon (C) budgets of the mesotidal Ria Formosa lagoon, southern Portugal, were estimated to reveal the main inputs and outputs, the seasonal patterns, and how they may influence the ecological functioning of the system. The effects of extreme weather events such as long-lasting strong winds...
Presentation
Full-text available
At present laboratory reagent companies are suspending supply of specialised agar products due to low availability of raw material. These bacteriological/technical agars used in laboratories around the world are predominantly obtained from species of a single red algal genus, Gelidium. Harvesting of natural populations is the only source of feedsto...
Article
Full-text available
Understanding how intra-specific differences in plant traits mediate vulnerability to herbivores of relevant habitat-forming plants is vital to attain a better knowledge on the drivers of the structure and functioning of ecosystems. Such studies, however, are rare in seagrass-mesograzer systems despite the increasingly recognized relevance of mesog...
Data
Variable loadings in the PCA examining relationships between Zostera noltei traits in low- (PRAIA) and high-vulnerability (QUINTA) plants (scaling 2, correlation biplot). (DOC)
Data
Pearson correlation statistics between Zostera noltei traits in low-vulnerability plants exposed to nutrient enrichment (r above and p-level below; n = 8). *Spearman correlations are shown for traits that had a non-normal distribution even after transformation. (DOC)
Data
Pearson correlation statistics between Zostera noltei traits in low- (PRAIA) and high-vulnerability (QUINTA) plants (r above and p-level below; n = 8). *Spearman correlations are shown for traits that had a non-normal distribution even after transformation. (DOC)
Data
Variable loadings in the PCA examining relationships between leaf traits of Zostera noltei plants exposed to nutrient enrichment (scaling 2, correlation biplot). (DOC)
Article
Full-text available
The seagrass ecosystem is an important natural carbon sink but the efficiency varies greatly depending on species composition and environmental conditions. What causes this variation is not fully known and could have important implications for management and protection of the seagrass habitat to continue to act as a natural carbon sink. Here, we as...
Article
Full-text available
Oyster farming in estuaries and coastal lagoons frequently overlaps with the distribution of seagrass meadows, yet there are few studies on how this aquaculture practice affects seagrass physiology. We compared in situ nitrogen uptake and the productivity of Zostera marina shoots growing near off-bottom longlines and at a site not affected by oyste...
Article
Full-text available
Temperature is not a limiting factor for the expansion of Halophila stipulacea throughout the whole Mediterranean Sea Dimos Georgiou, Ana Alexandre*, Joaquim Luis, Rui Santos *Email: aalexandre@ualg.pt ABSTRACT: Halophila stipulacea is a Lessepsian migrant that has spread from the Red Sea into the Mediterranean Sea where some authors consider it i...
Article
Full-text available
We assessed the combined effects of elevated CO2 and nutrients on the metabolism of a benthic community dominated by the seagrass Cymodocea nodosa (Ucria) Ascherson in a mesocosm experiment. C. nodosa plants and their associated community were exposed to two CO2levels simulating future (700 ppm, pH 7.84) and current (360 ppm, pH 8.12) conditions, a...
Article
Full-text available
BACKGROUND: Epiphytes impose physical barriers to light penetration into seagrass leaves causing shading, which may decrease the production of reactive oxygen species (ROS), but also constitute a physical aggression that may trigger the production of ROS, leading to oxidative damage. Here we investigate the effects of epiphytes on Posidonia oceanic...
Article
Full-text available
Grazing-induced plant defences that reduce palatability to herbivores are widespread in terrestrial plants and seaweeds, but they have not yet been reported in seagrasses. We investigated the ability of two seagrass species to induce defences in response to direct grazing by three associated mesograzers. Specifically, we conducted feeding-assayed i...
Article
Full-text available
Posidonia oceanica is a marine angiosperm, or seagrass, adapted to grow to the underwater life in very clear and shallow waters of 40 to 50 m depth. This raises questions of how their photosynthesis adapted to the attenuation of light through the water column and leads to the assumption that biochemistry and metabolism of the chloroplast are the ba...
Article
Full-text available
Submarine volcanic vents are being used as natural laboratories to assess the effects of increased ocean acidity and carbon dioxide (CO2) concentration on marine organisms and communities. However, in the vicinity of volcanic vents other factors in addition to CO2, which is the main gaseous component of the emissions, may directly or indirectly con...
Article
Full-text available
Hundreds of macroalgal species have been spread outside their natural range by human activities, and many of these introductions are occurring at a worldwide scale. This review considers one of the best-studied and most widespread invasive macroalgae, Sargassum muticum, to determine the traits and processes important in marine invasions and to iden...
Article
Coastal communities are under threat from many and often co-occurring local (e.g. pollution, eutrophication) and global stressors (e.g. climate change), yet understanding the interactive and cumulative impacts of multiple stressors in ecosystem function is far from being accomplished. Ecological redundancy may be key for ecosystem resilience, but t...
Conference Paper
Full-text available
Global climate changes are imposing multiple pressures to marine organisms. The rising atmospheric CO2 concentration is causing substantial changes in ocean physics, chemistry and biology. At least three synergic environmental stressors have been recognized as primary driven by CO2 emissions: ocean warming, oxygen loss and ocean acidification. The...
Article
Global climate changes are imposing multiple pressures to marine organisms. The rising atmospheric CO2 concentration is causing substantial changes in ocean physics, chemistry and biology. At least three synergic environmental stressors have been recognized as primary driven by CO2 emissions: ocean warming, oxygen loss and ocean acidification. The...
Article
Full-text available
The seagrass Posidonia oceanica is widely recognized as an effective bioindicator of the health status of Mediterranean coastal waters. Chlorophyll fluorescence measurements, in particular through the Pulse Amplitude Modulated (PAM) fluorometry method, are performed to study aquatic plant ecology and vitality and to assess their responses to divers...