Gabriel Navarro

• PhD University of Cadiz
• Researcher at Spanish National Research Council

The seagrass ecosystems are among the most important organic carbon sinks on Earth, having a key role as climate change buffers. Among all seagrasses, Posidonia oceanica, an endemic seagrass species in the Mediterranean Sea, has been observed to feature the highest carbon stock and sequestration rate among all seagrasses. We developed a satellite-b...

The EU funded project EuroSea brought together key actors of the European ocean observing and forecasting communities with key users of the ocean observing products and services in order to better integrate existing ocean observation systems and tools, and to improve the delivery of ocean information to users. EuroSea was constructed around the oce...

Intertidal areas, which emerge during low tide, form a vital link between terrestrial and marine environments. Seagrasses, a well-studied intertidal habitat, provide a multitude of different ecosystem goods and services. However, owing to their relatively high exposure to anthropogenic impacts, seagrasss meadows and other intertidal habitats have s...

Penguins play an essential biochemical role in the Antarctic ecosystem, being the study of their dynamics of utmost importance to understand their environment, behaviour and populational trends in the current climate change scenario. In this study, we used multi-rotor Unmanned Aerial Vehicles (UAVs) along the coast of the chinstrap penguin (Pygosce...

Deception Island (DI) is an active volcanic caldera in the South Shetland Islands, Antarctica, with an inner bay, Port Foster, formed by an ancient eruption. The bay’s seafloor hydrofracture system contains hydrothermal seeps and submarine vents, which are a source of trace metals (TMs) like Fe, Ni, Co, V, and greenhouse gases (GHGs) such as CO2 an...

Marine heatwaves are discrete, albeit prolonged, episodes of extreme ocean temperatures that are significantly impacting marine ecosystems worldwide. However, there is limited research solely focusing on marine heatwaves and their concomitant effects on ecosystem dynamics in the Southern Ocean, known to play a major role in the Earth’s climate syst...

Massive accumulations of invasive brown algae Rugulopteryx okamurae are exacerbating environmental and socio-economic issues on the Mediterranean and potentially Atlantic coasts. These golden tides, likely intensified by global change processes such as changes in wind direction and intensity and rising temperatures, pose increasing challenges to co...

Seagrasses are marine flowering plants that form extensive meadows from the inter-tidal zone up to ~50 m depth. As biological and ecological Essential Biodiversity Variables, seagrass cover and composition provide a wide range of ecosystem services. Inter-tidal seagrass meadows provide services to many ecosystems, so monitoring their occurrence, ex...

The Galician estuaries are Europe’s foremost supplier of mussels, generating millions of euros annually and offering substantial employment opportunities for its population. One of the most critical threats to shellfish production is the occurrence of harmful algal blooms (HABs), contaminating bivalves with phytotoxins. To successfully tackle this...

This study exploits the combination of High-Frequency Coastal Radar (HFR) information with satellite-derived observations to characterize the patterns involved in the coastal countercurrents (CCCs) events in the Gulf of Cadiz (GoC), which is situated in the SW of the Iberian Peninsula. The westward alongshore currents are observed throughout the ye...

The study of the functioning and responses of Antarctica to the current climate change scenario is a priority and a challenge for the scientific community aiming to predict and mitigate impacts at a regional and global scale. Due to the difficulty of obtaining aerial data in such extreme, remote, and difficult-to-reach region of the planet, the dev...

This work presents the steps followed in the design and implementation of a marine observatory that provides the current state and forecast of oceanic conditions relevant to the aquaculture sector. Examples of successful implementation of these guidelines are presented in the framework of the EuroSea project (H2020 grant agreement No. 862626) for t...

Aquatic ecosystems are crucial in preserving biodiversity, regulating biogeochemical cycles, and sustaining human life; however, their resilience against climate change and anthropogenic stressors remains poorly understood. Recently, unmanned aerial vehicles (UAVs) have become a vital monitoring tool, bridging the gap between satellite imagery and...

Extreme events are increasing in frequency and severity due to climate change, making the littoral zone even more vulnerable and requiring continuous monitoring for its optimized management. The low-lying Ebro Delta ecosystem, located in the NW Mediterranean, was subject to Storm Gloria in the winter of 2020, the most severe coastal storm registere...

Penguin colonies significantly influence the distribution and diversity of vegetation communities in Maritime Antarctica, as they serve as vital sources of nutrients for both terrestrial and aquatic ecosystems. Remote sensing techniques are becoming increasingly common for monitoring these vast Antarctic areas, especially with Un-manned Aerial Vehi...

The assessment of the saturation state (Ω) for calcium carbonate minerals (aragonite and calcite) in the ocean is important to determine if calcifying organisms have favourable or unfavourable conditions to synthesize their carbonated structures. This parameter is largely affected by ocean acidification, as the decline in seawater pH causes a decre...

The Guadalquivir estuary (southern Spain) occasionally experiences medium to high turbidity, reaching above 700 Formazin Nephelometric Unit (FNU) during extreme events, thus negatively influencing its nursery function and the estuarine community structure. Although several turbidity algorithms are available to monitor water quality, they are mainly...

Nearshore bathymetry is one of the main parameters used in coastal studies. However, regular and continuous bathymetries are scarce due to the difficulty of continuous data collection using traditional surveys. Remote sensing offers an attractive alternative to conventional collection methods for acquiring freely available, reliable, and frequent h...

Coastal hazards and extreme events are increasing in frequency and severity due to climate change, making the littoral zone even more vulnerable and requiring continuous monitoring for its optimized management. The Ebro Delta ecosystem, located in the NW Mediterranean, was subject to storm "Gloria" in the winter of 2020, the most severe coastal sto...

Iron plays a crucial role in the high-nutrient, low-chlorophyll Southern Ocean regions, promoting phytoplankton growth and enhancing atmospheric carbon sequestration. In this area, iron-rich Antarctic krill (Euphausia superba) and baleen whale species, which are among their main predators, play a large role in the recycling of iron. However, pengui...

The Mar Menor coastal lagoon in southeastern Spain has experienced a decline in water quality due to increased nutrient input, leading to the eutrophication of the lagoon and the occurrence of microalgal and macroalgal blooms. This study analyzes the macroalgal bloom that occurred in the lagoon during the spring-summer of 2022. A set of machine lea...

Harmful algal blooms (HABs) have severe environmental and economic impacts worldwide. Improving HAB detection is crucial because massive blooms are likely to increase in both frequency and amplitude in the next decades due to global warming and escalating coastal eutrophication. While satellite remote sensing has proved useful to detect red tides a...

The Galician Rías (northwestern Spain) are periodically affected by harmful algal blooms (HABs), mostly dinoflagellates, which pose a challenge to aquaculture activities due to the accumulation of biotoxins in shellfish. Typically, reddish blooms in the Rías are associated with non-toxic species like Noctiluca scintillans, with a few exceptions suc...

Remote-sensing ocean colour studies have already been used to determine coastal water quality, coastal biodiversity, and nutrient availability. In recent years, Unmanned Aerial Vehicles (UAVs) equipped with multispectral sensors, originally designed for agriculture applications, have also enabled water-quality studies of coastal waters. However, si...

Some Antarctic terrestrial ecosystems are greatly affected by climate change, especially in the northern Antarctic Peninsula region which has had the greatest temperature increase in the last 60 years. This increase has been more pronounced since 2017 and has caused a retreat of many glaciers. The retreat has caused the generation of soils, which a...

Remote sensing is the science of detecting, monitoring, and acquiring information about the physical characteristics of a certain area without actually coming into contact with it, contrary to in situ observations. This chapter on satellites and RPASs (remotely piloted aircraft systems) provides an introduction to remote sensing, including a brief...

Rugulopteryx okamurae is a species of brown macroalgae belonging to the Dictyotaceae family and native to the north-western Pacific. As an Invasive Alien Species (IAS), it was first detected in the Strait of Gibraltar in 2015. Since then, R. okamurae has been spreading rapidly through the submerged euphotic zone, colonizing from 0 to 50 m depth and...

Remote sensing has evolved as an alternative to traditional techniques in the spatio-temporal monitoring of the Antarctic ecosystem, especially with the rapid expansion of the use of Unmanned Aerial Vehicles (UAVs), providing a centimeter-scale spatial resolution. In this study, the potential of a high-spatial resolution multispectral sensor embedd...

Use of Earth Observation and remote sensing techniques for monitoring the marine invasive alien macrophyte R. okamurae in Tarifa (Spain). Use of multispectral (Landsat-8 and Sentinel-2) and hyperspectral (UAV) data and machine learning methods for classification mapping.

Monitoring for assessment of natural disasters, such as volcanic eruptions, presents a methodological challenge for the scientific community. Here, we present Unmanned Aerial Vehicles (UAVs) as a feasible, precise, rapid and safe tool for real time monitoring of the impacts of a volcanic event during the Cumbre Vieja eruption on La Palma Island, Sp...

Las Floraciones Algales Nocivas (FANs) son eventos comunes en las zonas costeras y aguas interiores, producidas por el aporte de nutrientes al agua (N y P) y las altas temperaturas (Gilbert y Burkholder, 2006), y en las últimas décadas están sufriendo un incremento en su frecuencia y extensión afectando a la economía local (Gobler, 2020). Suponen u...

Iron plays a crucial role in the high-nutrient, low-chlorophyll Southern Ocean regions, promoting phytoplankton growth and enhancing atmospheric carbon sequestration(1–5). In this area, the recycling of biogenic iron is partially driven by the iron-rich Antarctic krill (Euphausia superba), and baleen whale species as one of their main predators(6–1...

During recent years, several eutrophication processes and subsequent environmental cri-ses have occurred in Mar Menor, the largest hypersaline coastal lagoon in the Western Mediterra-nean Sea. In this study, the Landsat-8 and Sentinel-2 satellites are jointly used to examine the evolution of the main water quality descriptors during the latest ecol...

El cambio climático representa una amenaza a la integridad del sistema litoral que, sumado a la actividad de desarrollo y actividades económicas humanas, pone en riesgo la estabilidad de los sistemas oceánicos costeros, donde suele concentrarse gran parte de la población. En el litoral andaluz, las industrias acuícola y pesquera tienen una gran rel...

More than 60% of the world's population lives near coastal zones. These are the most productive as well as the most vulnerable ecosystems in the world. Considering these, among other factors, the study of coastal zones is a matter of vital importance, so that it is necessary to have accurate information for an appropriate coastal management. The sh...

Estuarine degradation is a major concern worldwide, and is rapidly increasing due to anthropogenic pressures. The Mediterranean Guadiaro estuary, located in San Roque (Cadiz, Spain), is an example of a highly modified estuary, showing severe negative effects of eutrophication episodes and beach erosion. The migration of its river mouth sand spit ca...

Monitoring water systems under extreme conditions or in remote areas poses a risk to scientists and staff involved, and can also result in disturbances to the local flora and fauna. In order to overcome these limitations, new techniques are being developed with the aim to gain more insight into how geochemical pathways of trace elements regulate th...

The photosymbiosis with host-specific dinoflagellates is a widespread relationship in marine organisms. Despite the evidenced biodiversity of this kind of mutualism, most research focuses on the study of scleractinian corals, and there is a lack of knowledge about other symbiotic cnidarians such as jellyfishes. The Mediterranean jellyfish Cotylorhi...

In this study, seawater quality was monitored with high-resolution satellite imagery during the 2021 volcanic eruption (September–December) on La Palma Island (Spain), the longest recorded in the history of the island, and the most destructive in the last century in Europe. The Sentinel-2A/B twin satellites and Landsat-8 satellite were jointly used...

The Island Mass Effect has been primarily attributed to nutrient enhancement of waters surrounding oceanic islands due to physical processes, whereas the role of land runoff has seldom been considered. Land runoff can be particularly relevant in mountainous islands, highly susceptible to torrential rainfall that rapidly leads to flash floods. Madei...

Antarctica plays a fundamental role in the Earth's climate, oceanic circulation and global ecosystem. It is a priority and a scientific challenge to understand its functioning and responses under different scenarios of global warming. However, extreme environmental conditions, seasonality and isolation hampers the efforts to achieve a comprehensive...

Marine macrophytes constitute one of the most productive ecosystems on the planet, as well as one of the most threatened by anthropogenic activities and climate change. Their monitoring is therefore essential, which has experienced a fast methodological evolution in recent years, from traditional in situ sampling to the use of satellite remote sens...

Laguna Lake, the largest freshwater lake in the Philippines, is permanently subject to nutrient-driven eutrophication and pollution and experiences harmful algal blooms (cyanoHABs) periodically with serious socio-economic implications. The aim of this study is to evaluate the suitability of the Sentinel-2 imagery of the European Commission’s Copern...

This study aimed at evaluating the ACOLITE atmospheric correction processor in order to develop a regional turbidity model for the Guadalquivir estuary (southern Spain) and its adjacent coastal region using Sentinel-2 imagery at a 10 m spatial resolution. Two settings for the atmospheric correction algorithm within the ACOLITE software were applied...

This volume illustrates the main research issues for the development of an environmental and economical sustainable primary production. An interdisciplinary collaboration between several scientific areas has allowed the study of the future evolution of agriculture, livestock and food production. The first chapters analyze the proper balance between...

Remote sensing techniques are becoming a key tool for coastal mapping in terms of resolution, effectiveness and cost reduction. Sentinel-2A/B twin satellites are part of the free and open policy programme available since 2015, but atmospheric corrections or cloud cover are still challenges to face. In order to process this data, cloud computing pla...

This campaign report collects the orthomosaics generated with the images obtained from Unmanned Aerial Vehicles (UAV) during the XXXIV Spanish Antarctic Campaign in Deception Island (South Shetlands Islands, Antarctica) as part of the PiMetAn polar project (Ref RTI2018-098048-B-100). PiMetAn Project (http://pimetan.csic.es/) aims to evaluate the ro...

1. Spatial modelling is an important research tool to improve our knowledge about the distribution of wildlife in the ocean. Using different modelling techniques (MaxEnt and a generalized linear mixed model), a predictive habitat suitability model was developed for one of the most threatened seabirds in the world: the Balearic shearwater, Puffinus...

Human mobilization during the COVID-19 lockdown has been reduced in many areas of the world. Maritime navigation has been affected in strategic connections between some regions in Patagonia, at the southern end of South America. The purpose of this research is to describe this interruption of navigation using satellite synthetic aperture radar data...

During the southern summer of 2020, large phytoplankton blooms were detected using satellite technology in Chile (western Patagonia), where intensive salmonid aquaculture is carried out. Some harvesting sites recorded massive fish mortalities, which were associated with the presence of the dinoflagellate species Cochlodinium sp. The bloom included...

The increased frequency of harmful algal blooms (HABs) is a major environmental concern worldwide, resulting not only in increased treatment costs for drinking water but also in impacts on tourism, commercial fishing and aquaculture and risks to human and animal health. Traditional strategies with ship-based approaches based on field sampling and l...

Global Fishing Watch and VIIRS-DNB (visible infrared imaging radiometer suite day/night band) signals are compared for the jigger fleet in FAO (Food and Agriculture Organization of the United Nations) Major Fishing Area 41 during the maximum feasible time span (2012–2018). Both signals have shown a high degree of consistency at all temporal and spa...

Flooding is among the most common natural disasters in our planet and one of the main causes of economic and human life loss worldwide. Evidence suggests the increase of floods at European scale with the Mediterranean coast being critically vulnerable to this risk. The devastating event in the West Mediterranean during the second week of September...

Coastal wetlands are significant sources of methane in the atmosphere, but emissions in these ecosystems are still poorly quantified, as in situ data are limited. In this study, we present the first assessment of spatio-temporal changes in air-water CH4 fluxes in the salt marshes of the Doñana wetlands (SW Spain), one of the most emblematic protect...

Two beaching events of the calycophoran siphonophore Abylopsis tetragona (Otto, 1823) were observed in two different areas of the Strait of Gibraltar during the cold season. The first was discovered on November 2014, on Getares Beach (Algeciras Bay, Mediterranean part of the Strait of Gibraltar), where more than 700 colonies were found deposited al...

Estuaries are significant methane (CH4) and nitrous oxide (N2O) emitters, although dynamics of both greenhouse gases in these ecosystems are regulated by complex processes. In this work, we aimed at characterizing the spatio-temporal distribution of CH4 and N2O in the Guadalquivir river estuary (SW Spain), the southernmost European estuary. During...

In this study, we apply high-resolution Sentinel-2A imagery to assist in the monitoring of the southwestern Spanish coast during its first year of data. The aim is to test suitability of MultiSpectral Imager (MSI) at higher resolution (10 m) for mapping Total Suspended Solids (TSS). Several field campaigns are carried out to collect TSS at three di...

High concentrations of suspended solids in coastal waters directly affect numerous processes. In the case of the marine region influenced by the Guadalquivir estuary, turbidity is one of the primary factors affecting this complex ecosystem and its adjacent coastal region. Ten-year (2002–2012) ocean color observations from the MEdium Resolution Imag...

High Amplitude Internal Waves (HAIWs) are physical processes observed in the Strait of Gibraltar (the narrow channel between the Atlantic Ocean and the Mediterranean Sea). These internal waves are generated over the Camarinal Sill (western side of the strait) during the tidal outflow (toward the Atlantic Ocean) when critical hydraulic conditions ar...

Dredging activities in estuaries frequently cause deleterious environmental effects on the water quality which can impact flora, fauna, and hydrodynamics, among others. A medium- and high-resolution satellite-based procedure is used in this study to monitor turbidity plumes generated during the dredging operations in the Guadalquivir estuary, a maj...

Cape Trafalgar has been highlighted as a hotspot of high chlorophyll concentrations, as well as a source of biomass for the Alborán Sea. It is located in an unique geographical framework between the Gulf of Cádiz (GoC), which is dominated by long-term seasonal variability, and the Strait of Gibraltar, which is mainly governed by short-term tidal va...

During the last two decades, several satellite algorithms have been proposed to retrieve information about phytoplankton groups using ocean color data. One of these algorithms, the so-called PHYSAT-Med, was developed specifically for the Mediterranean Sea due to the optical peculiarities of this basin. The method allows the detection from ocean col...

A forest fire started on August 8th, 2016 in several places on Madeira Island causing damage and casualties. As of August 10th the local media had reported the death of three people, over 200 people injured, over 950 habitants evacuated, and 50 houses damaged. This study presents the preliminary results of the assessment of several spectral indices...

Of all the gelatinous organisms species that usually appear on the Northern Alboran coast (Western Mediterranean), the most common and the one, which has the greatest negative impact on the ecosystem and on human coastal activities is the scyphozoa Pelagia noctiluca. This jellyfish has substantial socioeconomic consequences, causing major concern f...

A detailed study of the mechanisms generated through the turbidity plume and its variability at the Guadalquivir estuary has been carried out with remote sensing and in situ data. Several sensors with different characteristics have been required (spatial, temporal and spectral resolution), thereby providing information for a multi-sensor analysis....

The Guadalquivir estuary is one of the largest and most productive estuarine systems of the Western Europe. Located in the southwest coast of the Iberian Peninsula, its waters mix with those of the Gulf of Cadiz (Atlantic Ocean). The dynamics of its turbidity plume are important for the functioning of the estuary and the adjacent coastal region. Re...

Tempisque River runoff affect abundance and taxonomic composition of microplankton. • Five microplankton assemblages associated with a seasonal and river–marine gradient. • 146 microplanktonic taxa were identified, 52 of which were new citations in the area. • Phytoplankton were mainly limited by light rather than nutrients. • From ecotone model at...