Santiago Hernandez-Leon

• PhD
• Professor (Full) at University of Las Palmas de Gran Canaria

The short-term variability of plankton communities in the oceanic realm is still poorly known due to the paucity of high-resolution time-series in the open ocean. Among these few studies, there is compelling evidence of a lunar cycle of epipelagic zooplankton biomass in subtropical waters during the late winter bloom. However, there is few informat...

Copepods, the most abundant individuals of the mesozooplankton, play a pivotal role in marine food webs and carbon cycling. However, few studies have focused on their diversity and the environmental factors influencing it. The objective of the present study is to model the alpha and beta diversity of copepods across the tropical and subtropical eco...

Gaining robust in situ estimates of the growth rate of marine fish larvae is essential for understanding processes controlling year-class success and developing sustainable management strategies to maintain good environmental status. We measured the growth rate of Atlantic herring (Clupea harengus) larvae in the laboratory and compared it to the ac...

Euphausiids, commonly known as krill, are crucial contributors to the ocean’s active carbon pump, impacting carbon export and sequestration through their diel vertical migration. These organisms feed on organic matter in the epipelagic layer at night and release inorganic carbon in the mesopelagic layer during the day via respiration. Measuring res...

The biological carbon pump (BCP) is the mechanism by which the ocean transports organic matter below the mixed layer, exporting or sequestering it for years to millennia. Physical transport of dissolved and particulate organic carbon, the sinking of particles, and the carbon transported by diel and seasonal vertical migrants are the three main mech...

Documenting large-scale patterns of animals in the ocean and determining the drivers of these patterns is needed for conservation efforts given the unprecedented rates of change occurring within marine ecosystems. We used existing datasets from two global expeditions, Tara Oceans and Malaspina, that circumnavigated the oceans and sampled down to 40...

Copepods, the most abundant individuals of the mesozooplankton group, play a pivotal role in marine food webs and carbon cycling. However, few studies have focused on their diversity and the environmental factors influencing it. The objective of the present study is to model the alpha and beta diversity of copepods across the tropical and subtropic...

The twilight (200-1000 m depth) and midnight (1000-2000 m depth) zones are still nowadays one of the most unexplored places on earth, despite hosting one of the most diverse and biomass-rich environments. Active acoustics is one of the most employed techniques to investigate the twilight zone but vessel-borne echosounders are limited in depth due t...

There is a growing interest in the study of mesopelagic and bathypelagic species due to their implication in the active carbon flux and climate change. Underwater acoustics is one of the most efficient methods to study such widely distributed communities. However, there are several challenges among which the reduced spatial resolution with depth fo...

Carbon dioxide is increasing in the atmosphere promoting the faster environmental change of the Earth’s recent history. Several marine carbon dioxide removal (mCDR) technologies were proposed to slow down CO2 in the atmosphere. Technologies now under experimentation are related to the increase in gravitational flux. Other mechanisms such as active...

The shallow Tagoro submarine volcano monitoring represents a unique opportunity not only for improving our sparse understanding of submarine volcanic processes in specific scientific fields as physical and chemical oceanography or marine geology but also its interactions over the marine biology in one of the richest marine ecosystems in Europe. Thi...

Non-migratory bristlemouth fishes (Cyclothone spp.) are the most abundant vertebrates on Earth and play an important role in the biological carbon pump by remineralizing organic carbon in deep ecosystems. Acoustic data and net sampling are often used in combination to estimate fish and zooplankton biomass, but this procedure may be subject to sever...

Changes in plankton composition influences the dynamics of marine food webs and carbon sinking rates. Understanding the core structure and function of the plankton distribution is of paramount importance to know their role in trophic transfer and efficiency. Here, we studied the zooplankton distribution, abundance, composition, and size spectra for...

There is a growing interest in the study of mesopelagic and bathypelagic micronektonic species due to ecological reasons, their potential commercial explotation and their implication in the active carbon flux. Vessel-borne echosounders have been widely employed for their study but the limitation in range, particularly for the higher frequencies, ha...

Slipper (Scyllaridae) and spiny (Palinuridae) lobsters show a complex life cycle with a planktonic larval phase, named phyllosoma. This unique larval form within Achelata (Decapoda) is characterized by a transparent dorsoventrally compressed body and a pair of antennae. This conspicuous morphology has been attributed to adaptive specialization of p...

Plankton are an important component of life on Earth. Since the 19th century, scientists have attempted to quantify species distributions using many techniques, such as direct counting, sizing, and classification with microscopes. Since then, extraordinary work has been performed regarding the development of plankton imaging systems, producing a ma...

The fish body shape is a key factor that influences multiple traits such as swimming, foraging, mating, migrations, and predator avoidance. The present study describes the body morphological changes and the growth trajectories during the transformation from 24 to 54 days post-hatching in the golden grey mullet, Chelon auratus, using geometric morph...

Most mesopelagic fishes perform large diel vertical migrations from the deep-sea zone to the surface. Although there is a trade-off between a higher food availability at the upper layers and an energy cost and predation risk, incursion towards the surface also implies a transport by currents, where the fish are exposed to a stranding risk on the co...

The biological carbon pump is the process that transports carbon vertically out of the mixed layer in the ocean. Besides the sinking flux of organic particles, active flux due to the daily vertical migration of zooplankton and micronekton promotes a significant carbon transport not fully accounted for or understood in the world’s oceans. The divers...

For this experimental study, we set two sampling times for fish ages 24 and 54 days post hatching (dph). To characterize the morphology of body shape was used GMA methodology followed the landmarks-based method. The ETS activity was measured following the method modified by Gómez et al. (1996). To determine biomass in terms of protein was used the...

Understanding the causes of global sea level rise is considered as an important goal of climate research on a regional scale, especially around islands, owing to their vulnerability to this phenomenon. In the case of the Canary Islands, these alterations entail an increase in territorial risks. The Canary Islands span the transitional zone linking...

Lanternfishes are the dominant component of mesopelagic fishes living in the ocean between 200 and 1000 m depth, playing a key role in the food web of oceanic ecosystems (Catul et al., 2011). Most mesopelagic fishes perform large diel vertical migrations from the deep-sea zone, where they stay during the day, to the surface where they feed at night...

We did zooplankton sampling on board the R.V. Angeles Alvariño (IEO) for 12 days around Canary Island, as part of RAPROCAN_2203 project. We analyzed mithocondrial enzymatic activity of the electron transfer system (ETS) as a proxy for zooplankton respiration. We also analyzed proteins for biomass. The objective was to measure the carbon active flu...

Supplementary information to 'Deep ocean prokaryotes and fluorescent dissolved organic matter reflect the history of the water masses across the Atlantic Ocean'.

Organic matter is known to influence community composition and metabolism of marine prokaryotes. However, few studies have addressed this linkage in the deep ocean. We studied the relationship between fluorescent dissolved organic matter and prokaryotic community composition in meso- and bathypelagic water masses along a surface productivity gradie...

The organic carbon resulting from photosynthesis in the upper ocean is transferred downward through the passive sinking of organic particles, physical mixing of particulate and dissolved organic carbon as well as active flux transported by zooplanktonic and micronektonic migrants. Several meso- and bathypelagic organisms feed in shallower layers du...

The trophic position (TP) of fishes determines their importance in terms of energy flows within food webs. However, accurate estimations of TP are often prevented because of the difficulties in tracing all food sources. This is particularly challenging for omnivorous fishes, such as those from the Order Stomiiformes. In this study, we applied recen...

The importance of microbes for the functioning of oceanic food webs is well established, but their relevance for top consumers is still poorly appreciated. Large differences in individual size, and consequently in growth rates and the relevant spatial and temporal scales involved, make the integration of microorganisms and large metazoans in a comm...

Fishes are the dominant vertebrates in the ocean, yet we know little of their contribution to carbon export flux at regional to global scales. We synthesize the existing information on fish-based carbon flux in coastal and pelagic waters, identify gaps and challenges in measuring this flux and approaches to address them, and recommend research prio...

The biological pump transports organic carbon produced by photosynthesis to the meso-and bathypelagic zones, the latter removing carbon from exchanging with the atmosphere over centennial time scales. Organisms living in both zones are supported by a passive flux of particles, and carbon transported to the deep-sea through vertical zooplankton migr...

Subtropical gyres are large areas of the ocean characterized by high stratification, low nutrients, and low primary production. The Canary Current System (CanCS) shows a rather strong seasonal thermocline during most of the annual cycle, which erodes through convective mixing from January to March promoting the so-called Late Winter Bloom (LWB). At...

Climate evolves following natural variability, and knowledge of these trends is of paramount importance to understand future scenarios in the frame of global change. Obtaining local data is also of importance since climatic anomalies depend on the geographical area. In this sense, the Canary Current is located in one of the major eastern boundary c...

Abstract. Climate evolves following natural variability and knowledge of these trends is of paramount importance to understand future scenarios in the frame of global change. Obtaining local data is also of importance since climatic anomalies depend on the geographical area. In this sense, the Canary Current is located in one of the major eastern b...

Quantification of the actual amount of carbon export to the mesopelagic layer by both zooplankton and micronekton is at present a gap in the knowledge of the biological pump. These organisms perform diel vertical migrations exporting carbon through respiration, excretion, mortality, and egestion during their residence at depth. The role of zooplank...

Respiration in the mesopelagic layer is rather difficult to estimate but is of paramount importance to assess active flux, the downward carbon transport carried out by diel vertical migrants in the ocean. Migrant biomass and respiration in the mesopelagic zone are required to estimate respiratory flux, an important component of active flux. Three m...

Saharan dust events are currently the predominant source of lithogenic particles in the Canary Basin. In order to quantify this input and its relationship with the biogenic fluxes, a sediment trap was deployed in a free-drifting system at 150 m depth, 50 km off the north coast of Gran Canaria (Canary Islands). The mineralogy of the lithogenic parti...

Lanternfishes (Myctophidae) constitute the most important component of the daily vertically migrating mesopelagic fish community. This research addresses the estimation of the trophic position and diet of myctophids using stable isotope analyses. Fishes were collected across the central Atlantic, from a very productive zone influenced by the Maurit...

Knowledge of metabolic rates of euphausiid diel vertical migrants in the ocean is of paramount importance to understand the role of these organisms in the downward transport of carbon due to their feeding in the epipelagic zone and subsequent respiration, egestion, excretion and mortality in the mesopelagic zone. Enzymatic activities are used as pr...

Abstract Oligotrophic and productive areas of the ocean differ in plankton community composition and biomass transfer efficiency. Here, we describe the plankton community along a latitudinal transect in the tropical and subtropical Atlantic Ocean. Prochlorococcus dominated the autotrophic community at the surface and mixed layer of oligotrophic sta...

Knowledge of metabolic rates of euphausiid diel vertical migrants in the ocean is of paramount importance to understand the role of these organisms in the downward transport of carbon due to their feeding in the epipelagic zone and subsequent respiration, egestion, excretion and mortality in the mesopelagic zone. Enzymatic activities are used as pr...

Zooplankton vertical distribution, migrant biomass, and respiratory flux were studied in two transects performed in the Canary Current at 21°N and 26°N from the eu- and mesotrophic upwelling zone off Northwest Africa to the oligotrophic central gyre waters. Migrant biomass was estimated by sampling during day and night using a Longhurst-Hardy Plank...

Plankton living in the deep ocean either migrate to the surface to feed or feed in situ on other organisms and detritus. Planktonic communities in the upper 800 m of the tropical and equatorial Atlantic were studied using the natural abundance of stable carbon and nitrogen isotopes to identify their food sources and trophic diversity. Seston and zo...

Winter 2010 was the warmest of the last 30 years in the subtropical oceanic waters north of the Canary Islands. Sea surface temperature was always above 19°C, promoting a strong stratification and preventing the expected late winter bloom. The knowledge of how planktonic organisms respond to such a warm scenario is of paramount importance to predic...

We investigate the transport dynamics of decapod larvae in the Canary-African coastal transition zone (C-ACTZ), where larval assemblages are poorly known. In August 1999, during the FAX99 cruise, the waters downstream of the Canary Island archipelago displayed intense mesoscale activity, with numerous cyclonic and anticyclonic eddies as well as upw...

Top-down effects in the pelagic realm are quite well known in freshwater ecosystems. However, our knowledge of these effects in the ocean remains scant. It is known that copepods prefer to prey on ciliates and heterotrophic dinoflagellates, and their high or low abundances can change the structure of microplankton communities. Field studies in subt...

Here we show the main distribution characteristics of marine copepods across the subtropical-tropical latitudes and to bathypelagic depths in the Atlantic, Indian and Pacific Oceans (35°N-40°S). The copepod samples were collected from December 2010 to June 2011 during the Malaspina Circumnavigation Expedition. Epipelagic (0-200 m), mesopelagic (200...

Several new approaches for measuring zooplankton growth and production rates have been developed since the publication of the ICES (International Council for the Exploration of the Sea) Zooplankton Methodology Manual (Harris et al., 2000). In this review, we summarize the advances in biochemical methods made in recent years. Our approach explores t...

Remineralization of organic matter in the mesopelagic zone (ca. 150–700 m) is a key controlling factor of carbon export to the deep ocean. By using a tracer conservation model applied to climatological data of oxygen, dissolved inorganic carbon (DIC) and nitrate, we computed mesopelagic respiration at the ESTOC (European Station for Time-Series in...

Diel vertical migration (DVM) facilitates biogeochemical exchanges between shallow waters and the deep ocean. An effective way of monitoring the migrant biota is by acoustic observations although the interpretation of the scattering layers poses challenges. Here we combine results from acoustic observations at 18 and 38 kHz with limited net samplin...

Measuring zooplankton biomass and physiological rates is of paramount importance in biological oceanography in order to assess the role of this community in, e.g. carbon fluxes. Classical methods (incubations) are very time-consuming and cannot match the frequency of physical and chemical measurements. Attempting to solve this, a variety of methods...

The submarine volcano eruption off El Hierro Island (Canary Islands) on 10 October 2011 promoted dramatic perturbation of the water column leading to changes in the distribution of pelagic fauna. To study the response of the scattering biota, we combined acoustic data with hydrographic profiles and concurrent sea surface turbidity indexes from sate...

Significance High concentrations of floating plastic debris have been reported in remote areas of the ocean, increasing concern about the accumulation of plastic litter on the ocean surface. Since the introduction of plastic materials in the 1950s, the global production of plastic has increased rapidly and will continue in the coming decades. Howev...

To establish a metabolic state along a north–south transect in Antarctic waters, we approached community respiration (CR) from a combined perspective based on the metabolic theory of ecology (MTE) and the size-scaling of the whole planktonic community. A detailed analysis of a summer integrated multi-trophic normalized biomass size spectra (NBSS),...

The spatial distribution of fish larvae was studied in the Canaries-African Coastal Transition Zone, outside the strong upwelling season. An onshore–offshore transition in the larval fish community structure was observed, from a coastal assemblage dominated by small pelagics (sardine, anchovy, mackerel), bounded by the upwelling front, to an offsho...

We describe the coupling between upper ocean layer variability and size-fractionated phytoplankton distribution in the non-nutrient-limited Bransfield Strait region (BS) of Antarctica. For this purpose we use hydrographic and size-fractionated chlorophyll a data from a transect that crossed 2 fronts and an eddy, together with data from 3 stations l...

With a current estimate of ~1,000 million tons, mesopelagic fishes likely dominate the world total fishes biomass. However, recent acoustic observations show that mesopelagic fishes biomass could be significantly larger than the current estimate. Here we combine modelling and a sensitivity analysis of the acoustic observations from the Malaspina 20...

The microbial planktonic community of the subtropical waters around Gran Canaria Island, Canary Islands, was studied before, during and after the typical late winter bloom. The study consisted of a weekly sampling from October 2005 to June 2006 at five stations. Abundances and biomass of heterotrophic prokaryotes, small autotrophic plankton (picopl...

Planktonic larvae constitute a vital component of oceanic food webs and represent the early life-history stages of ecologically and economically valued species. Thus, understanding biological and physical mechanisms involved with larval transport is of substantial interest to the fields of ecology, conservation and fishery management. This study re...

The Canary Current has experienced a progressive warming and a decrease in productivity over the last decades. In order to study the effect of stratification in these waters, we conducted a weekly sampling at one station (28°04′N 15°21′E) located ∼3 nmi offshore in the 100 m isobath, at the edge of the island shelf of Gran Canaria Island (Canary Is...

The plankton community response to natural fertilization caused by the Saharan dust was studied in the Canary Islands waters during winter-spring 2010. For this, a weekly sampling was carried out to characterize the pico-, nano- and microplankton communities. During this period several dust events were identified from atmospheric suspended matter a...

Here we review all published data on phytoplankton growth and microzooplankton grazing using the dilution technique to better understand the role of this group of grazers in different regions of the oceans, and to identify the knowledge gaps that require future efforts. A total of 1525 data points assimilated from 110 studies were included and grou...

We studied the relationship between atmospheric dust deposition, N2 fixation rates, and the abundance of unicellular diazotrophs and Trichodesmium in weekly or biweekly samplings over 3 months in the Canary Islands. On average, N2 fixation rates by unicellular diazotrophs and Trichodesmium were low (0.2 nmol N L-1 h-1 and 1.66 3 10 23 nmol N L-1 h-...

Three types of primary productivity (PP) models were evaluated in a mesoscale area around the South Shetland Islands (Antarctica). Input variables were: phytoplankton carbon biomass, Chlorophyll a, sea water temperature, daily irradiance, among others, collected in situ during an oceanographic cruise (COUPLING, January 2010). Models of the first ty...

Larval transport strongly influences neritic populations of oceanic islands. We investigated the spatial-temporal variability of the assemblage of decapod larvae at the shelf edge off Gran Canaria Island. Environmental and planktonic monitoring were conducted weekly from January to July 2001, at three stations located at different positions in rela...

Biomass, abundance, gut fluorescence and electron transfer system (ETS) activity of zooplankton have been studied in the Bransfield Strait (Antarctic Peninsula). Two well-defined frontal systems were observed: (1) the so-called Peninsula front between the Transitional Bellingshausen Water (TBW) and Transitional Weddell Waters (TWW); and (2) the Bra...

[This corrects the article DOI: 10.1038/srep00486.].

During the austral summer, zooplankton excretion along the western Antarctic Peninsula was studied in a contrasting hydrographic regime including coastal and oceanic waters. In coastal waters, ammonium supply by mesozooplankton indicated a low contribution to fuel primary production. In oceanic waters, however, Antarctic krill Euphausia superba con...

On October 10 2011 an underwater eruption gave rise to a novel shallow submarine volcano south of the island of El Hierro, Canary Islands, Spain. During the eruption large quantities of mantle-derived gases, solutes and heat were released into the surrounding waters. In order to monitor the impact of the eruption on the marine ecosystem, periodic m...

Planktonic biomass from heterotrophic prokaryotes to mesozooplankton was assessed in the Canary Island waters in order to study the characteristic late winter bloom of subtropical waters. Weekly sampling was performed between January and August 2005 at 6 stations around the island of Gran Canaria. The bloom observed in this study showed the common...

The in situ activity of the enzymes aminoacyl-tRNA synthetases (AARS) and the growth rates of naupliar stages of the planktonic marine copepod Paracartia grani were measured in the laboratory under different temperature and food concentrations. We assessed the effect of these parameters on growth and protein synthesis rates of P. grani nauplii. Gro...

High-resolution data collected southeast of the Canary Islands during late winter 2006 are analyzed to describe the hydrography and three-dimensional circulation in the coastal transition zone off NW Africa. The data are optimally interpolated over a regular grid, the geostrophic velocity field is calculated and the Q-vector formulation of the omeg...

Studies on carbon active fluxes due to diel migrants are scarce and critical for carbon flux models and biogeochemical estimates. We studied the temporal variability and vertical distribution of biomass, indices of feeding and respiration of the zooplanktonic community north off the Canary Islands during the end of the late winter bloom, in order t...

Aeolian dust plays an important role in climate and ocean processes. Particularly, Saharan dust deposition is of importance in the Canary Current due to its content of iron minerals, which are fertilizers of the ocean. In this work, dust particles are characterized mainly by granulometry, morphometry and mineralogy, using image processing and scann...