Publications

Light availability in the coastal ocean: impact on the distribution of benthic photosynthetic organisms and contribution to primary production

International audience

Projected Changes in Photosynthetic Picoplankton in a Warmer Subtropical Ocean

The oligotrophic subtropical gyres are the largest biome on Earth, where picoplankton constitute the dominant autotrophs. The trend for autotrophic picoplankton to increase with sea temperature has led to predictions that picophytoplankton abundance will increase with warming. Here we conducted a global survey in the open subtropical-tropical ocean to resolve the functional relationships between picophytoplankton abundance and oceanic properties (water temperature, chlorophyll a concentration, nutrient concentrations, and underwater visible and ultraviolet B radiation). We then used these relationships to build models projecting the future changes of Synechococcus, Prochlorococcus and eukaryotic picoautotrophs populations in the subtropical gyres with warming. Our goal is to refine the forecasts for this large biome and implement the analysis by including the picoeukaryotes, absent in previous models, but a relevant component of picophytoplankton. The data obtained and the relationships found in our global survey of the subtropical-tropical ocean between picophytoplankton abundance and ocean properties differed from previous global studies including colder (temperate, subpolar and polar) and coastal waters. These differences included a lower abundance of Synechococcus populations, significant negative relationships between Prochlorococcus abundance and nutrient concentrations, and positive relationships for picoeukaryotes and no relationship for Synechococcus abundance, and, a moderate response to temperature in the warm waters of the tropical-subtropical open ocean. A model based on temperature increase alone forecasts a general increase in picoautotrophs by year 2100, although minimal for picoeukaryotes, and much more moderate for Synechococcus than previously forecasted. However, a global change model linking the thermal increase with the associated decline in chlorophyll a, and increased underwater solar radiation penetration, projected a decline in the abundance of autotrophic picoplankton. The decline was larger at the surface layer and partially compensated by the increased importance of deep picophytoplankton blooms, especially those of Prochlorococcus. The global change model predicted an increased dominance of Prochlorococcus sp. in the subtropical-tropical ocean with future warming. Our results, based on current patterns of picophytoplankton distribution, help improve existing projections by considering feedbacks affecting picophytoplankton abundance in the future subtropical and tropical ocean, the larger biome on Earth. In memoriam of Prof. Luis M. Lubián, an outstanding researcher and friend

Major Expansion of Marine Forests in a Warmer Arctic

Accelerating warming and associated loss of sea ice are expected to promote the expansion of coastal marine forests (macrophytes) along the massive Arctic coastlines. Yet, this region has received much less attention compared to other global oceans. The available future projections of Arctic macrophytes are still limited to few species and regions, and mostly focused at lower latitude ranges, thus precluding well-informed IPCC impact assessments, conservation and management. Here we aim to quantify potential distributional changes of Arctic intertidal and subtidal brown macroalgae and eelgrass by the year 2100, relative to present. We estimate habitat suitability by means of species distribution modeling, considering changes in seawater temperature, salinity, nutrients and sea ice cover under two greenhouse gas emission scenarios, one consistent with the Paris Agreement (RCP 2.6) and the other representing limited mitigation strategies (RCP 8.5). As data on substrate conditions do not exist, the models were restricted to the depth range supporting Arctic macrophytes (down to 5 m for eelgrass and 30 m for brown macroalgae). Models projected major expansions of Arctic macrophytes between 69,940 and 123,360 km 2 , depending on the climate scenario, with polar distribution limits shifting northwards by up to 1.5 latitude degrees at 21.81 km per decade. Such expansions in response to changing climate will likely elicit major changes in biodiversity and ecosystem functions in the future Arctic. Expansions are, however, less intense than those already realized over the past century, indicating an overall slowing down despite accelerated warming as habitats become increasingly occupied.

Is Global Ocean Sprawl a Trojan Horse for Jellyfish Blooms

La exploración de la biodiversidad marina: Desafíos científicos y tecnológicos

Restarting the conversation: challenges at the interface between ecology and society

The exchange of information between researchers, resource managers, decision makers, and the general public has long been recognized as a critical need in environmental science. We examine the challenges in using ecological knowledge to inform society and to change societal actions, and identify a set of options and strategies to enhance this exchange. Our objectives are to provide background information on societal knowledge and interest in science and environmental issues, to describe how different components of society obtain information and develop their interests and values, and to present a framework for evaluating and improving communication between science and society. Our analysis strongly suggests that the interface between science and society can only be improved with renewed dedication to public outreach and a wholesale reconsideration of the way that scientists communicate with society. Ecologists need to adopt new models of engagement with their audiences, frame their results in ways that are more meaningful to these audiences, and use new communication tools, capable of reaching large and diverse target groups.

Bacterial degradation of organic matter in the surface microlayer of the Arctic and Antarctic Oceans

Poster presentado en el VIII Simposio de Estudios Polares (8th Symposium on Polar Studies), celebrado del 7 al 9 de septiembre de 2011 en Palma de Mallorca (Espana)

Tackling unethical authorship deals on scientific publications

The Northern Red Sea (Shushah Island) Coral Health Inferred from Benthic Foraminifers

The northeastern Red Sea (Saudi Arabia) is currently being transformed to become a global hub of economic activity and tourism. This transformation requires the development of pristine coastal areas into populated and dynamic settlements. At the same time, the northern Red Sea is considered a climate refuge for corals in changing climate conditions, and efforts to preserve and protect marine biodiversity are being proposed. Accordingly, foraminifers are an efficient tool to assess and monitor their associated coral reefs’ health. This study reports a modern-day health assessment of the corals of Shushah Island (Saudi Arabia) in the northeastern Red Sea as a reference for future monitoring as inferred by applying the FoRAM Index method. In general, our results revealed healthy conditions conducive to coral growth, yet some precautions and regular assessments are recommended.

Fingerprinting Blue Carbon: Rationale and Tools to Determine the Source of Organic Carbon in Marine Depositional Environments

Blue carbon is the organic carbon in oceanic and coastal ecosystems that is captured on centennial to millennial timescales. Maintaining and increasing blue carbon is an integral component of strategies to mitigate global warming. Marine vegetated ecosystems (especially seagrass meadows, mangrove forests, and tidal marshes) are blue carbon hotspots and their degradation and loss worldwide have reduced organic carbon stocks and increased CO2 emissions. Carbon markets, and conservation and restoration schemes aimed at enhancing blue carbon sequestration and avoiding greenhouse gas emissions, will be aided by knowing the provenance and fate of blue carbon. We review and critique current methods and the potential of nascent methods to track the provenance and fate of organic carbon, including: bulk isotopes, compound-specific isotopes, biomarkers, molecular properties, and environmental DNA. We find that most studies to date have used bulk isotopes to determine provenance, but this approach often cannot distinguish the contribution of different primary producers to organic carbon in depositional marine environments. Based on our assessment, we recommend application of multiple complementary methods. In particular, the use of carbon and nitrogen isotopes of lipids along with environmental DNA have a great potential to identify the source and quantify the contribution of different primary producers to sedimentary organic carbon in marine ecosystems. Despite the promising potential of these new techniques, further research is needed to validate them. This critical overview can inform future research to help underpin methodologies for the implementation of blue carbon focused climate change mitigation schemes.

Diversity and distribution of coral gall crabs associated with Red Sea mesophotic corals

Coral-dwelling gall crabs (Cryptochiridae) live in an obligate symbiosis with reef-building corals from shallow to deep waters. In particular, crabs of the genus Opecarcinus are known to occur across the tropical belt in association with the scleractinian family Agariciidae, down to a depth of 89 m. The Red Sea is a semi-enclosed basin that has long been recognized as a region of high marine biodiversity and endemism, with more than 230 decapod species recorded so far. There, nine Opecarcinus species are recorded from shallow and mesophotic corals. However, the occurrence of Opecarcinus below 30 m depth is documented only in the Saudi Arabian coast of the Northern Red Sea, and the rest of the Saudi Arabian Red Sea has remained unstudied. In this work, we assess the diversity and distribution of Opecarcinus from the mesophotic waters of the Saudi Arabian Red Sea. Through Remotely Operated Vehicles (ROV) and Submarines explorations, we collected 10 gall crab specimens associated with Agariciidae corals at mesophotic depths between 47 and 89 m. Two mitochondrial and one nuclear markers were used to obtain crab phylogenetic tree showing that three of the Opecarcinus species known from Red Sea shallow-water corals can also live at mesophotic depths. This is the first assessment of the depth distribution of the genus Opecarcinus in the Red Sea. It provides further evidence of the depth range adaptability of the Opecarcinus -Agariciidae association and highlights the need for a more in-depth investigation of the largely overlooked mesophotic coral-associated fauna.

Functional metagenomic analysis of dust-associated microbiomes above the Red Sea

Abstract Atmospheric transport is a major vector for the long-range transport of microbial communities, maintaining connectivity among them and delivering functionally important microbes, such as pathogens. Though the taxonomic diversity of aeolian microorganisms is well characterized, the genomic functional traits underpinning their survival during atmospheric transport are poorly characterized. Here we use functional metagenomics of dust samples collected on the Global Dust Belt to initiate a Gene Catalogue of Aeolian Microbiome (GCAM) and explore microbial genetic traits enabling a successful aeolian lifestyle in Aeolian microbial communities. The GCAM reported here, derived from ten aeolian microbial metagenomes, includes a total of 2,370,956 non-redundant coding DNA sequences, corresponding to a yield of ~31 × 10 6 predicted genes per Tera base-pair of DNA sequenced for the aeolian samples sequenced. Two-thirds of the cataloged genes were assigned to bacteria, followed by eukaryotes (5.4%), archaea (1.1%), and viruses (0.69%). Genes encoding proteins involved in repairing UV-induced DNA damage and aerosolization of cells were ubiquitous across samples, and appear as fundamental requirements for the aeolian lifestyle, while genes coding for other important functions supporting the aeolian lifestyle (chemotaxis, aerotaxis, germination, thermal resistance, sporulation, and biofilm formation) varied among the communities sampled.

Annual variation in leaf photosynthesis and leaf nutrient content of four Mediterranean seagrasses

We examine here the annual variation in leaf photosynthesis and nutrient status of four temperate seagrass species: Posidonia oceanica, Cymodocea nodosa, Zostera noltii, and Zostera marina. We also examine the relationship between leaf photosynthesis and seasonal plant growth and productivity. The four seagrass species examined co-occurred in a shallow protected cove on the NE Spanish Mediterranean coast. The results presented give evidence of large annual variation in the leaf physiological status of these four seagrasses, as well as the occurrence of significant differences in the seasonal pattern among species. We found two contrasting seasonal patterns characterized by optimal leaf photosynthesis in summer (represented by C. nodosa), and winter-autumn (represented by P. oceanica and Z. noltii). These contrasting patterns corresponded with a differential plant dependence on climate fluctuations (described by temperature and irradiance) vs. speciesspecific nutrient status (described by leaf nutrient content). As plant nutrient status results from speciesspecific differences in nutrient requirements, nutrient uptake efficiency, and internal nutrient economy, we conclude that the variation among species found in leaf nutrient content derives from species-specific responses to environmental forcing. Consequently, we can infer that an important fraction of the seasonal variability that seagrasses show may be related to species-specific responses. We also found significant differences among species in the coupling between leaf photosynthesis and plant growth and productivity. Both aspects, speciesspecific responses to environmental forcing and speciesspecific coupling between leaf photosynthesis and plant growth may result in differential seasonal patterns of growth and productivity among seagrass species.

Bacterioplankton dark CO₂ fixation in oligotrophic waters

Abstract. Dark CO2 fixation by bacteria is believed to be particularly important in oligotrophic ecosystems. However, only a few studies have characterized the role of bacterial dissolved inorganic carbon (DIC) fixation in global carbon dynamics. Therefore, this study quantified the primary production (PP), total bacteria dark CO2 fixation (TBDIC fixation), and heterotrophic bacterial production (HBP) in the warm and oligotrophic Red Sea using stable-isotope labeling and cavity ring-down spectroscopy (13C–CRDS). Additionally, we assessed the contribution of bacterial DIC fixation (TBDIC %) relative to the total DIC fixation (totalDIC fixation). Our study demonstrated that TBDIC fixation increased the totalDIC fixation from 2.03 to 60.45 µg C L−1 d−1 within the photic zone, contributing 13.18 % to 71.68 % with an average value of 33.95 ± 0.02 % of the photic layer totalDIC fixation. The highest TBDIC fixation values were measured at the surface and deep (400 m) water with an average value of 5.23 ± 0.45 and 4.95 ± 1.33 µg C L−1 d−1, respectively. These findings suggest that the non-photosynthetic processes such as anaplerotic DIC reactions and chemoautotrophic CO2 fixation extended to the entire oxygenated water column. On the other hand, the percent of TBDIC contribution to totalDIC fixation increased as primary production decreased (R2=0.45, p<0.0001), suggesting the relevance of increased dark DIC fixation when photosynthetic production was low or absent, as observed in other systems. Therefore, when estimating the total carbon dioxide production in the ocean, dark DIC fixation must also be accounted for as a crucial component of the carbon dioxide flux in addition to photosynthesis.

Common photosinthetic enzymes from 174 metagenomes from the Malaspina Expedition 2010 (Ortega et al. 2019)

Predicted genes corresponding to the four most common enzymes present in photosynthetic organisms: NADH:ubiquinone reductase (H+-translocating), N-acetyl-gamma-glutamyl-phosphate reductase, DNA-directed RNA polymerase and non-specific serine/threonine protein kinase of 174 metagenomes sequenced during the Malaspina 2010 global expedition. From: Alejandra Ortega, Nathan R Geraldi, Intikhab Alam, Allan A Kamau, Silvia G Acinas, Ramiro Logares, Josep M Gasol, Ramon Massana, Dorte Krause-Jensen and Carlos M Duarte. Important contribution of macroalgae to oceanic carbon sequestration. Nature Geoscience.

Identification of suspicious behaviour through anomalies in the tracking data of fishing vessels

Automated positioning devices can generate large datasets with information on the movement of humans, animals and objects, revealing patterns of movement, hot spots and overlaps among others. This information is obtained after cleaning the data from errors of different natures. However, in the case of Automated Information Systems (AIS), attached to vessels, these errors can come from intentional manipulation of the electronic device. Thus, the analysis of anomalies can provide valuable information on suspicious behaviour. Here, we analyse anomalies of fishing vessel trajectories obtained with the Automatic Identification System. The map of silence anomalies, those occurring when positioning data is absent for more than 24 h, shows that they occur more likely closer to land, observing 94.9% of the anomalies at less than 100 km from the shore. This behaviour suggests the potential of identifying silence anomalies as a proxy for illegal activities. With the increasing availability of high-resolution positioning of vessels and the development of powerful statistical analytical tools, we provide hints on the automatic detection of illegal activities that may help optimise monitoring, control and surveillance measures.

Rapid Evolution of SARS-CoV-2 Challenges Human Defenses

Abstract Evolutionary ecology theory provides an avenue to anticipate the future behavior of SARS-CoV-2. Here we quantify the accelerating evolution of SARS-CoV-2 by tracking the SARS-CoV-2 mutation globally, with a focus on the Receptor Binding Domain (RBD) of the spike protein believed to determine infectivity. We estimate that 384 million people were infected by March 1st, 2021, producing up to 10 21 copies of the virus, with one new RBD variant appearing for every 600,000 human infections, resulting in approximately three new effective RBD variants produced daily. Doubling the number of RBD variants every 71.67 days followed by selection of the most infective variants challenges our defenses and calls for a shift to anticipatory, rather than reactive tactics. One-Sentence Summary Accelerating evolution of SARS-CoV-2 demands formulating universal vaccines and treatments based on big-data simulations of possible new variants.

Mass mortality events in Mediterranean marine coastal ecosystems

The Mass Mortality Events database (hereafter MME-T-MEDNet) is a collaborative initiative involving more than 30 research institutions from 10 Mediterranean countries including EU and non-EU countries. This initiative aims to facilitate the access to information (published in scientific journals and gray literature or still unpublished) related to Mediterranean Mass Mortality Events (MMEs).