Daniel Robledo

• Oceanography (BSc); Marine Sciences (PhD)
• Senior Researcher at Center for Research and Advanced Studies of the National Polytechnic Institute

Marine macrophytes are considered promising biomass for bioethanol production. The increases in anthropogenic nutrients and climate change have caused unprecedented blooming of ‘sargasso’ across the Atlantic since 2011. This biomass reaches the Caribbean Sea, stranding in large amounts along shorelines, and creating a serious waste management probl...

Gracilaria cornea was exposed to different irradiance intensities (low, moderate, and high) and light qualities (white and white + blue) in experimental cultures. Photosynthetic physiology was measured through daily growth rate, maximum photosynthesis, maximum photochemical efficiency, pigment content (chlorophyll a, phycobiliproteins, carotenoids)...

In the Mexican Caribbean, the magnitude of the Sargassum events and the uncoordinated efforts have made it difficult to achieve successful management. This study contributes to understanding the dynamics of the Sargassum accumulations on a sandy beach in Puerto Morelos, Quintana Roo, through monitoring for 18 months (2018–2019). Temporal changes in...

Species of holopelagic Sargassum are responsible for Caribbean golden tides, commonly known as ‘ Sargassum events’. These events mainly comprise Sargassum fluitans and Sargassum natans I, which are exposed to high levels of irradiance, but also self‐shading within their floating masses. In this study, we grew S. fluitans and S. natans I and acclima...

Seaweed farming worldwide has increased considerably in the last century. Latin America (LATAM) has an enormous potential to contribute within the medium/long term to global seaweed production. However, the seaweed sector is not exempted by risks (e.g. diseases and pests) overall understudied in the region, reason why biosecurity and traceabilit...

In the last decade, massive events of Sargassum influx have been reported causing ecological and economic damages. In this study, we evaluated the antioxidant potential of the holopelagic species S. fluitans, S. natans I, and S. natans VIII which arrived during 2018–2019 on the Mexican Caribbean coast. The monthly and intra- thallus variation of...

Even after hundreds of clinical trials, the search for new antivirals to treat COVID-19 is still relevant. Carrageenans are seaweed sulfated polysaccharides displaying antiviral activity against a wide range of respiratory viruses. The objective of this work was to study the antiviral properties of Halymenia floresii and Solieria chordalis carragee...

Solieria spp. (Solieriaceae, Gigartinales, Rhodophyta) can be found in various habitats ranging from the marine environment to low-salinity estuarine environments. Of the commercially exploited carrageenophytes, some of the most abundant belong to the Solieriaceae family as, Kappaphycus, Eucheuma and Solieria. The supply of these seaweeds is ensure...

Seaweed surface provides a suitable substratum for the settlement of microorganisms (bacteria, viruses, and plankton). These microbial partners may have either beneficial or detrimental effects on the host since surface microbiota can act either as a protective layer to the macroalgae (symbiotic beneficial relations) or, under changing environmenta...

On the Mexican coasts, carrageenophytes are harvested from natural populations and exported as raw material for the extraction of carrageenan. Hypnea musciformis, a native species to the Gulf of Mexico and Caribbean Sea, is an economically important seaweed due to its kappa/iota carrageenan content, and as a source of different bioactive compounds....

In the last decade, massive events of Sargassum influx have been reported causing ecological and economic damages. In this study, we evaluated the antioxidant potential of the holopelagic species S. fluitans , S. natans I, and S. natans VIII that arrived during 2018–2019 on the Mexican Caribbean coast. The seasonality and intra-thallus variation (a...

When the COVID-19 pandemic reached the Mexican Caribbean in late March 2020, this world-renown tourist destination had already been struggling with Sargassum influxes for 5 years. The nature and magnitude of these two impacts are not directly comparable, but both have contributed to profoundly transforming the region. As extreme COVID-19 containmen...

Herpes simplex virus 1 (HSV-1) remains a prominent health concern widespread all over the world. The increasing genital infections by HSV-1 that might facilitate acquisition and transmission of HIV-1, the cumulative evidence that HSV-1 promotes neurodegenerative disorders, and the emergence of drug resistance signify the need for new antiviral agen...

Graphene and its derivates are at the center of an ever-growing research effort due to their exceptional properties; however, their applications remain limited due to high production costs. Obtaining carbonaceous bidimensional materials from biomass is now intensively studied; however, most methodologies are based on controlled atmosphere (N2) and...

Since 2014, the Mexican Caribbean beaches have received massive influxes of the brown seaweed Sargassum (S. fluitans III, S. natans I and S. natans VIII), causing serious ecological and economic effects. Concentrations of arsenic (As), cadmium (Cd), copper (Cu), iron (Fe), lead (Pb), and zinc (Zn) were determined over an annual cycle in pelagic Sar...

Mass blooms and stranding of pelagic Sargassum spp. in the Atlantic, termed Sargassum events are becoming more frequent in response to several factors: nutrient enrichment, increased temperature, changes in climatological patterns, but some causes remain unknown. The magnitude of Sargassum events in the Caribbean Sea since 2011 make us aware of the...

In the last decade, unprecedented arrivals of pelagic Sargassum (Sargassum influx) have been reported for the Caribbean coasts causing severe ecological and economical affectations and remarking the necessity to characterize the phenomenon. In the north coast of the Mexican Caribbean, spatial characterization of Sargassum influx was performed in te...

In this study, we evaluated the interactive effects of temperature, pH, and nutrients on photosynthetic performance in the calcareous tropical macroalga Halimeda scabra . A significant interaction among these factors on gross photosynthesis ( P gross ) was found. The highest values of P gross were reached at the highest temperature, pH, and nutrien...

Solieria filiformis has been reported to havemolecules with various biological activities. In this studywe used environmentally friendly extraction methods, such as enzyme-assisted extraction (EAE), as a first step to obtain bioactive compounds from this species. Five combinations of protease (PRO) and carbohydrase (AMG)were utilized (1:0, 0:1, 2:1...

The genus Sargassum is well represented by benthic and pelagic species, some of which forms massive aggregates that can travel large distances due to the force of the ocean currents. Although they constitute an essential habitat for fish and invertebrate species, large accumulations of Sargassum in coastal areas generates several economic, environm...

Macroalgae host a dense bacterial epibiome forming surface biofilms, which act as a biological defense by protecting the surface from macrofoulers. During experimental cultivation of Halymenia floresii (Rhodophyta, Halymeniales) under Integrated MultiTrophic Aquaculture (IMTA), the culture tanks remained clean of any exogenous algal colonization, a...

Short-term effects of pCO 2 (700-380 ppm; HC-LC) and nitrate content (50-5 M; HN-LC) on photosynthesis, estimated by different pulse amplitude modulated (PAMs) fluorometers and by oxygen evolution, were investigated in Ulva rigida (Chlorophyta) under solar radiation (ex-situ) and in the laboratory under artificial light (in-situ). After 6-days of...

Massive accumulations of pelagic species of Sargassum have generated recent social, economic and ecological problems along Caribbean shores. In the Mexican Caribbean, these events have prompted the study of diverse biological and ecological aspects of these macroalgae. However, studies on their associated biota, including Hydrozoa, remain scarce. T...

Seaweeds can produce certain pigments under specific light, salinity, and nutrient conditions. These pigments have important biological activities, which have been cited in numerous published literature; thus, they have been considered of nutraceutical importance. Solieria filiformis and Gracilaria cornea (Rhodophyta) have been studied for their ab...

The filamentous green seaweed Chaetomorpha can grow in a wide range of salinities and temperatures, and it is often reported as nuisance in other cultures due to its proliferation capacity and ordinarily discarded. However, Chaetomorpha can represent a promising feedstock for different purposes due to their potential valuable compounds. In the pres...

During the experimental cultivation of the red alga Halymenia floresii under Integrated MultiTrophic Aquaculture (IMTA), the establishment of opportunist green algae and the colonization of sessile invertebrates, which were usually disturbing the cultivation, were not observed. The culture tanks were clean and the surface of the H. floresii was rem...

Several species of Sargassum have been reported from the Yucatan peninsula coast, many of which end up as beach cast material, accumulating on the coast during colder months. The phenotypic plasticity of Sargassum makes specimen identification difficult. Two approaches were used in the current study to corroborate identification of the most abundan...

Historically, enzyme-assisted extraction was applied to seaweeds to find a new ecofriendly way for phycocolloid extraction. A first evolution in the use of this novel extraction method leads to active fractions from seaweeds (not only polysaccharides) for agriculture, health, food, feed, or cosmetic applications. Since 2015, a second evolution has...

Seaweed farming has now expanded across several continents from South East Asia to South America, Northern Europe, Canada and East Africa, contributing to global food security, supporting rural livelihoods, alleviating poverty and improving the health of oceans. Latin America (LA) covers a vast geographical area, which includes four different ocean...

Rhodymenia pseudopalmata lives in the intertidal zone receiving high doses of solar radiation, including the potentially harmful UVR. Previous studies proved it ability to adapt to different artificial light intensities and salinity concentrations. The aim of this study was to describe the differences on the Mycosporine-like amino acids (MAAs), phe...

High diversity of marine macroalgae is reported for Mexican coasts, including numerous endemic species. Seaweed research in Mexico has focused on the northern regions of the Pacific coast (Temperate Pacific and Gulf of California) and on the Mexican Caribbean coast, leaving aside other regions (Tropical Pacific and Gulf of Mexico). Utilization of s...

Macroalgae surfaces are considered as a potentially suitable substratum present underwater for the dynamic epibiotic microbiome. They secrete various organic substances as nutrients for the multiplication of bacteria and the formation of microbial biofilms. The microbial biofilm itself acts as a biological defence mechanism to prevent the establish...

Marine macroalgae (seaweed) are an excellent source of novel bioactive metabolites. The biorefinery concept applied to seaweed facilitates the extraction of many chemical constituents from the same biomass ensuring that the resource is used fully, generating few residues through a succession of extraction steps. In the present study, the biomass of...

Genetic continuity of Digenea simplex outside the Atlantic waters remains less studied, despite its long exposure to oriental folk medicine and wide distribution in tropical waters. Mitochondrial COI-5P and plastid rbcL sequences and morphology were investigated for plants from Mexico and additional specimens from Japan. Two new species, Digenea me...

Kappaphycus and Eucheuma species have been successfully cultivated in Southeast Asia since the early 1970s. The increasing global demand for carrageenan in processed foods and thereby the need for industrial-scales of biomass to be provided to feed an extraction industry, exceeded wild stock availability and productivity and commercial demands coul...

Growth, biochemical composition and antioxidant capacity of Rhodymenia pseudopalmata were studied under controlled laboratory conditions. Cultures were exposed to five salinities ranging from 20, 25, 30, 35 and 40 psu under three photosynthetic active radiations (PAR) 50, 100 and 200 μmol photons m⁻²s⁻¹. Rhodymenia pseudopalmata daily growth rates...

Carrageenan yield, physicochemical properties, and antiviral activity of the carrageenan from Solieria chordalis (Rhodophyceae, Solieriaceae) harvested at the Brittany coast (France) were investigated. S. chordalis carrageenan was extracted by conventional and the microwave assisted extraction (MAE) methods. The effect of different parameters durin...

Fucoidans are sulfated polysaccharides with proven pharmacological effects localized in the cell wall of marine brown algae. The majority of studies have been performed with temperate brown algal species, but in recent years, the evaluation of species from tropical areas has been growing. The aim of this study was to determine the protective effect...

Introduced Marine Pests (IMP, = non-indigenous marine species) prevention, early detection and risk-based management strategies have become the priority for biosecurity operations worldwide, in recognition of the fact that, once established, the effective management of marine pests can rapidly become cost prohibitive or impractical. In Western Aust...

Polysaccharides extracted from Rhodymenia pseudopalmata, Solieria filiformis, Hydropuntia cornea (Rhodophyta) and Sargassum fluitans (Phaeophyceae) were evaluated for its cytotoxic and antiviral activities against Herpes simplex virus (HSV-Type 1). Chemical structures were characterized by FT-IR spectroscopy and 13C-NMR analyses. Polysaccharides fr...

Crude and alkali treated carrageenan from the cultivated marine alga Solieria filiformis (Rhodophyta) were obtained, characterized and evaluated for their cytotoxic and antiprotozoal activities. Yields, molecular weights and chemical composition of carrageenans were determined. Their structures were elucidated through spectroscopic techniques inclu...

Rhodymenia pseudopalmata is a red alga that grows at the Caribbean coast of the Yucatan Peninsula and has been proven successful in cultivation. In this study we present the lipid composition of R. pseudopalmata collected from wild populations during three different seasons of 2013. Cultured material was also analyzed and compared in order to evalu...

Sulfated polysaccharides (SPs) extracted from five seaweed samples collected or cultivated in Mexico (Macrocystis pyrifera, Eisenia arborea, Pelvetia compressa, Ulva intestinalis, and Solieria filiformis) were tested in this study in order to evaluate their effect on measles virus in vitro. All polysaccharides showed antiviral activity (as measured...

The aim of this research was to evaluate the physiological and biochemical responses of R. pseudopalmata to solar irradiation under exposed conditions of culture. Maximum Quantum Yield of PSII (Fv/Fm), antioxidant capacity and Anti‐UV compounds were evaluated.

Seaweed tissue cultures have been established before to study the effect of plant growth regulators (PGR) with contradictory results. Particularly the axenity of such cultures is questioned, and the relationship of epiphytic/endophytic bacteria with macroalgae may affect the interaction of PGR described before. In this study we aim to quantify the...

Hypnea musciformis is one of the most studied species of the genus Hypnea. It has a wide geographic range along the Atlantic, Pacific and Indian Oceans that would be consistent with an extensive intraspecific variation in morphology. Hypnea musciformis has been previously reported on coasts of the Yucatan Peninsula; however, neither morphological c...

Carrageenans are a class of sulfated galactans extracted from different species of red seaweed (Rhodophyta). This family of polysaccharides has a galactose backbone, which differs in the proportion and location of the ester sulfate groups and the proportion of 3,6- anhydrogalactose groups. The differences in composition and conformation produce a w...

Kappaphycus alvarezii (Rhodophyta) is an important source of carrageenan, which is commercially cultivated with economic benefits worldwide. In this study, we determined the optimal harvesting time and risk analysis for the mariculture of K. alvarezii in a semi-intensive commercial cultivation farm using a simulation model. Different growth models...

The farming of the red seaweed Kappaphycus alvarezii and related species as raw material for the hydrocolloid carrageenan rapidly spread from the Philippines in the late 1960s to Indonesia, Tanzania, and other tropical countries around the world. Although numerous studies have documented positive socioeconomic impacts for seaweed farming, factors s...

GuA r di A nes de n u estro fu tu ro A MbientA L L a contaminación ambiental, las especies exóticas invasoras y el cam-bio climático global entre otros, pueden alterar de manera severa la estabilidad de los ecosistemas y por ende a la biodiversidad que en ellos habita. En consecuencia, es imperativo identificar de mane-ra temprana las señales que n...

Photosynthesis is the ultimate natural process that supports all the biofuels generation. Photosyntetic production of hydrogen by microalgae is very attractive from the renewability point of view. Moreover, it faces several challenges: since the process itself has a low yield, a large number of considerations should be studied to optimize the hydro...

Three macroalgal species belonging to Chlorophyta (Ulva rigida), Rhodophyta (Ellisolandia elongata) and Phaeophyceae (Heterokontophyta; Cystoseira tamariscifolia), naturally growing at the same shore level and representing 3 morpho-functional groups, were exposed to short-term changes in temperature under different carbon and nitrogen regimes. Expe...

Short-term effects of increasing pCO2; 380 ppm (LC) vs. 700 ppm (HC); at different nitrogen levels; 5 μM nitrate (LN) vs. 50 μM (HN); on the contents of protein, mycosporine-like amino acids (MAAs), phenolic compounds and total fatty acids, antioxidant activity, calcification and C:N ratios were analyzed in 3 eulittoral Mediterranean macroalgae wit...

Reactive oxygen species (ROS) are involved in initiating and promoting several hepatic diseases. This study was designed to evaluate the in vitro hepatoprotective effect and antioxidative activity of the fucoidan extract from Turbinaria tricostata (FTt) from the coast of the Yucatan Peninsula (Mexico). We compared two different mild condition extra...

Gracilariopsis tenuifrons is a red alga living in the upper intertidal zone of Playa de Carmen (Quintana Roo, Mexico), where abiotic stressors occur over the year. A high antioxidant capacity has been previously demonstrated for G. tenuifrons from the Mexican Caribbean. In this study, we evaluated the photosynthetic activity, pigment composition an...

Context: The hexane extracts of Dictyota ciliolata Sonder ex Kützing (Dictyotaceae), Padina sanctae-crucis Børgesen (Dictyotaceae), and Turbinaria tricostata E.S. Barton (Sargassaceae) were found to exhibit cytotoxic and antiproliferative activities in vitro. Bioactive compounds responsible for these activities have not been studied in detail for...

The European, Canadian, and Latin American seaweed industries rely on the sustainable harvesting of natural resources. As several countries wish to increase their activity, the harvest should be managed according to inte- grated and participatory governance regimes to ensure pro- duction within a long-term perspective. Development of regulations an...

Phenolics, sometimes called polyphenolic compounds, are present in a variety of terrestrial and marine plants. They are utilized as important components of both human and animal diets for their antioxidant capacity. More than 8000 phenolic structures are currently known (Bravo 1998). To date, most polyphenols isolated from marine sources and refere...

Phenolics, sometimes called polyphenolic compounds, are present in a variety of terrestrial and marine plants. They are utilized as important components of both human and animal diets for their antioxidant capacity. More than 8000 phenolic structures are currently known (Bravo 1998). To date, most polyphenols isolated from marine sources and refere...

Seasonal variation of fatty acid composition of Halymenia floresii (Rhodophyta algae) was determined by conventional methods and gas chromatography-mass spectrometry (GC-MS). Three saturated fatty acids (SAFA) were identified (C14:0, C16:0, C18:0) and a monounsaturated (MUFA) C18:1 Δ9. Results indicated a cons-tant SAFA/MUFA proportion throughout t...

Hypnea musciformis (Wulfen in Jacqu.) J. V. Lamour. (Rhodophyta) was investigated for its carrageenan production. Traditionally, the desulfation process for carra-geenans has been promoted by an alkaline treatment of up to 3 h by conventional heating during carrageenan extraction. New extraction techniques based on microwave irradiation may acceler...

The Latin American seaweed industry plays an important role at a global scale as 17 % of all seaweeds and 37 % of red seaweeds for the phycocolloid industry comes from this region. Increased market demand for algal raw materials has stimulated research and development into new cultivation technologies, particularly in those countries with economica...

In the Yucatan Peninsula coast, a large diversity of seaweed species are found, and recent studies have reported the presence of metabolites with pharmaceutical importance. In this study, a biological screening of brown seaweed extracts from Dictyota ciliolata, Padina sanctae-crucis, Sargassum fluitans, and Turbinaria tricostata was carried out. Th...

This chapter focuses on the socio-economic analysis of the Dzilam de Bravo experience in seaweed farming, which is, at the time of writing, the only known case in Mexico in which coastal communities have been involved in this activity. Regarding the history of seaweed aquaculture in Mexico, only scientific and technical information deriving from ac...

In this study, we have tested the effect of seaweed stocking density in an experimental seaweed bio-filter using the economically important red sea-weed Hydropuntia cornea integrated with the cultivation of the pink shrimp Farfantepenaeus bra-siliensis. Nutrient removal efficiency was evaluated in relation to seaweed stocking density (2.5, 4, 6 and...

Polysaccharides composition of the tropical brown seaweeds Turbinaria turbinata, Sargassum filipendula, Dictyota caribaea and Padina perindusiata collected at Yucatan Peninsula (Mexico) was determined in this study. Crude fucoidan extracted with HCl and alginate extracted with a hot alkali solution were characterized in terms of their molecular wei...

Seasonal variation of fatty acid composition of Halymenia floresii (Rhodophyta algae) was determined by conventional methods and gas chromatography-mass spectrometry (GC-MS). Three saturated fatty acids (SAFA) were identified (C14:0, C16:0, C18:0) and a monounsaturated (MUFA) C18:1 Δ9. Results indicated a constant SAFA/MUFA proportion throughout th...

Carpospore output and development in the marine red alga Hydropuntia cornea J. Agardh. were increased by adding polyamines (PAs) (putrescine, spermidine and spermine) singly or in combinations at 10(-9), 10(-6) and 10(-3) M. Cell divisions after spore release and development of apical axis between 17 and 21 days characterized carpospore development...

Only water hydrolysis with renewable energies is a sustainable process for hydrogen production. Biohydrogen production is an interesting alternative that is being explored at the scientific level. The microalgae Chlamydomonas reinhardtii has been extensively studied and used as a model for the photo-production of H2. The aim of this proposal is to...

Agar obtained from the red alga Hydropuntia cornea was blended with polyvinyl alcohol (PVOH) in order to produce biodegradable films. In this study, we compare the properties of biopolymeric films formulated with agars extracted from H. cornea collected at different seasons (rainy and dry) in the Gulf of Mexico coast and PVOH as synthetic matrix. T...

Very few studies have been performed to evaluate the effect of culture conditions on the production or activity of active metabolites in algae. Previous studies suggest that the synthesis of bioactive compounds is strongly influenced by irradiance level. To investigate whether the antiproliferative activity of Udotea flabellum extracts is modified...

Carrageenan, a hydrocolloid used in the food and pharmaceutical industry mainly as a thickener and stabilizer, has an annual global market of US $450 million. In Mexico, carrageenan imports doubled during the last years, reaching 4,400t in 2008. Any carrageenan industrial project demands a regular supply of raw material from reliable sources capabl...

Purpose: Extracts of the green alga, Penicillus dumetosus, have shown antiproliferative activity against several cancer cell lines. The aim of this study was to evaluate if this activity is modified after cultivation. Methods: P. dumetosus was cultured under different light treatments. After 10, 20 and 30 days, alga samples were collected and their...