Sergio Seoane

Universidad del País Vasco / Euskal Herriko Unibertsitatea | UPV/EHU · Vegetal Biology and Ecology

Microbial eukaryotes are small and often resistant to standard labelling and imaging techniques, and therefore remain understudied - despite their critical ecological importance - with the exception of a few established models. Here, we use Ultrastructure Expansion Microscopy (U-ExM) to carry out high-resolution volumetric imaging of over 200 cultu...

Phytoplankton monitoring is essential for understanding the functioning of aquatic ecosystems and for assessing water quality. Based on pigment analysis, different mathematical tools have been developed to relate pigments and phytoplankton groups and determine the contribution of each of these groups to the total phytoplankton biomass. However, mos...

The continuous increase in carbon dioxide (CO 2) levels stands as a major driver of climate change, prompting the need to seek sustainable means of carbon sequestrion in urban areas. Microalgae have emerged as a promising solution due to their efficient photosynthesis [1]. The concept of "liquid trees," employing microalgae as capture CO 2-systems,...

Phycobiliproteins (PBP) are bioactive pigments with many applications in human health and nutrition. Consequently, there is a growing interest in the use of PBP in different industrial applications. Among macroalgae, PBP are present mainly in red algae but their concentrations can vary seasonally and also depend on the processing made. In this cont...

Pigments play a vital role in the photosynthesis process and are responsible for the colour of the different groups of algae. Furthermore, these pigments contain bioactive compounds, with diverse applications in human health, nutrition, and biotechnology. Consequently, there is a growing interest in them for industrial purposes. In this context, th...

Ostreopsis is a potentially toxic benthic dinoflagellate genus whose presence has been related to toxic outbreaks affecting humans with symptoms such as coughing, fever, rhinorrhoea, mild breathing problems and skin irritation. Since the first report in the Basque Country in 2007, its abundance and distribution have grown to such an extent that, in...

Ostreopsis is a potentially toxic benthic dinoflagellate genus that, originally, was mostly distributed in warm and tropical waters. Its presence has been related to toxic outbreaks affecting humans with symptoms such as coughing, fever, rhinorrhoea, mild breathing problems and skin irritation. Since the first report in the Basque Country in 2007,...

Reports of the benthic dinoflagellate Ostreopsis spp. have been increasing in the last decades, especially in temperate areas. In a context of global warming, evidences of the effects of increasing sea temperatures on its physiology and its distribution are still lacking and need to be investigated. In this study, the influence of temperature on gr...

Artificial lighting with light-emitting diodes (LED) is proposed as a suitable solution to reach stable yearly production of high value molecules from microalgae under unfavorable climates. However, available studies are inconsistent regarding the effect of LED color on cultures performance. This study examined the response of Arthrospira platensis...

Pigment analysis through high-performance liquid chromatography (HPLC) offers a faster and more replicable study of the phytoplankton community structure than traditional taxonomy, but its application to small-sized freshwater ecosystems is infrequent. We carried out a taxonomy-based validation for the application of HPLC to the management of two a...

Phytoplankton monitoring is essential for understanding the functioning of aquatic ecosystems and for assessing water quality. Based on pigment analysis, different mathematical tools have been developed to relate pigments and phytoplankton groups and determine the contribution of each of these groups to the total phytoplankton biomass. However, mos...

Seaweed are organisms rich in many bioactive compounds such as proteins, minerals, vitamins, fibers, essential amino acids, pigments, and fatty acids, which give them extraordinary antihypertensive, antidiabetic, antioxidant, anti-inflammatory, antitumoral, antiviral, and antimicrobial properties. Seaweed could potentially contribute to future glob...

Marine microalgae have potential to be low-cost raw materials. This depends on the exploitation of different biomass fractions for high-value products, including unique compounds. Chrysochromulina rotalis, an underexplored haptophyte with promising properties, was the focus of this study. For the first time, C. rotalis was successfully cultivated i...

Phytoplankton monitoring is essential for the global understanding of aquatic ecosystems. The present research studies the phytoplankton community of the Urdaibai estuary, combining microscopy and eDNA metabarcoding for the first time in the area. The main aims were to describe the phytoplankton community composition in relation to the environmenta...

In recent years, the interest in nutrition and healthful living has increased and consumers are looking for healthy alternatives as a food source. Gastronomic products and practices based on macroalgae are exponentially increasing. The objective of the present work was to characterize six common macroalgae species of the Basque Coast: green (Ulva r...

Ostreopsis is a potentially toxic benthic dinoflagellate genus mostly distributed in warm and tropical waters. Its presence has been related to toxic outbreaks affecting humans. Since the first report in the Basque Country in 2007, its abundance and distribution has grown to such an extent that, in summer 2021, toxic blooms of these dinoflagellates...

The red tide-forming microalga Heterosigma akashiwo has been associated with massive events of fish deaths, both wild and cultured. Culture conditions are responsible for the synthesis or accumulation of some metabolites with different interesting bioactivities. H. akashiwo LC269919 strain was grown in a 10 L bubble column photobioreactor artificia...

Harmful algal blooms (HABs) in coastal areas similarly impact both ecosystems and human health. The translocation of phytoplankton species via maritime transport can potentially promote the growth of HABs in coastal systems. Accordingly, ballast water must be disinfected. The main goal of this study is to assess the effectiveness of different emerg...

During a prokaryotic diversity study in Añana Salt Valley, a new Rhodobacteraceae member, designated ASV31T, was isolated from Santa Engracia spring water. It was extremely halotolerant, tolerating up to 23% NaCl, and facultatively alkaliphilic, growing at pH 6.5–9.5 (optimum at 7.0–9.5). The isolate was a Gram-negative, rod-shaped, aerobic and non...

Anthropic nutrient enrichment has become a major environmental issue in estuaries around the world, being the effluents of wastewater treatment plants (WWTPs) one of the main causes. Phytoplankton is, together with nutrients, a useful indicator for the ecological status assessment of estuaries due to its basal position in the food chain. The presen...

Phytoplankton monitoring is essential for the global understanding of aquatic ecosystems, due to its important role as major primary producer. Traditionally, optical microscopy has been used for the analysis, but alternative methods based on the pigment analysis by HPLC and CHEMTAX are gaining importance lately. The present research studies the phy...

A novel salt-tolerant alpha-proteobacterium, designated SALINAS58 T , was isolated from Santa Engracia hypersaline spring water in the Añana Salt Valley, Álava, Spain. The isolate was Gram-negative, aerobic, non-motile, catalase-positive, oxidase-negative, rod-shaped and formed orange colonies on marine agar. Optimal growth was observed at pH 6.0–6...

The phylogenetic diversity of Ochrophyta, a diverse and ecologically important radiation of algae, is still incompletely understood even at the level of the principal lineages. One taxon that has eluded simple classification is the marine flagellate genus Olisthodiscus. We investigated O. luteus K‐0444, and documented its morphological and genetic...

In a future scenario of increasing temperatures in North‐Atlantic waters, the risk associated with the expansion of the harmful, benthic dinoflagellate Ostreopsis cf. siamensis has to be evaluated and monitored. Microscopy observations and spatio‐temporal surveys of environmental DNA (eDNA) were associated with Lagrangian particle dispersal simulat...

Akuikulturak azken hamarkadan mundu mailan izan duen garapena itzela izan da eta, honek, Euskal Autonomia Erkidegoan (EAEn) moluskuen akuikultura burutzeko nahia piztu du. Gaur egun, muskuiluak ekoizten berriki hasi den akuikultura eremu bakarra dago EAEn, itsaso zabalean kokatuta, Mendexako kostaldearen aurrean. Hala ere, sektorea gehiago garatzek...

"Marine and estuarine plankton ecology" group of the Department of Plant Biology and Ecology is made up of eleven researchers: six lectures, a PhD researcher, and four doctoral researchers. The activity of the group focuses on the monitoring of the plankton ecosystem, especially, on the influence of natural and anthropic factors on the zooplankton....

This study describes the phytoplankton community in sheltered euhaline waters of the Basque coast (southeastern Bay of Biscay). Phytoplankton composition, cell size, abundance, biomass and the presence of potentially toxic taxa, together with chlorophyll a, nutrients and hydrographic and optical conditions were measured, from August 2016 to August...

The composition and dynamics of microalgae play an important role in shellfish aquaculture, since phytoplankton is the main source of energy for filter-feeding bivalves as well as the main potential toxicity risk. Together with the increase in world aquaculture production in the last decades, there is recent interest in the implementation of shellf...

Phytoplankton communities have long been used as water quality indicators within environmental policies. This has fostered the development of national and international phytoplankton monitoring programs, but these networks are subject to sources of uncertainty due to laboratory issues. Nevertheless, studies regarding the interference associated wit...

This study focused on the phytoplanktonic community of lake Sanabria (NW Spain) during the mixing period. We integrated the classic phytoplankton counting method and the pigment analysis via high performance liquid chromatography, to obtain a global image of the community structure, which was very similar among the study zones and unaltered despite...

Early stage identification of harmful algal blooms (HABs) has gained significance for marine monitoring systems over the years. Various approaches for in-situ classification have been developed. Among them, pigment-based taxonomic classification is one promising technique for in-situ characterization of bloom compositions, although it is yet undere...

We present the data corresponding to the isolation and morphological and molecular characterization of a strain of Amphidinium carterae, isolated in Mallorca Island waters and now deposited in the microalgae culture collection of the Plant Biology and Ecology Department of the University of the Basque Country under the reference Dn241Ehu. The morph...

The feasibility of the long-term (>170 days) culture of a dinoflagellate microalga in a raceway photobioreactor is demonstrated for the first time. Amphidinium carterae was chosen for this study as it is producer of interesting high-value compounds. Repeated semicontinuous culture provided to be a robust operational mode. Different concentration le...

In the present study, seasonal variability of physico-chemical variables and phytoplankton community as well as their relationships were studied for oligotrophic coastal waters of southeastern Bay of Biscay. During a 4-year period (2012–2015), a total of 265 phytoplankton taxa were identified, mainly represented by dinoflagellates and diatoms. The...

We report here the complete chloroplast genome sequences of seven strains of the bloom-forming raphidophyte Heterosigma akashiwo . These ~160-kb sequences contain 124 protein-, 6 rRNA-, and 34 tRNA-coding sequences. Notable sequence variations were observed among these seven sequenced and two previously characterized strains.

Bioprospecting of plankton has become an important industry during last years. The challenge of living longer and healthier and avoiding the destruction of our planet, forces us to discover new ways to produce food, energy fuel or healthy products apart from traditional agriculture or nonrenewable energies. The plankton characteristics of growth an...

In the last decades there has been a great development in aquaculture worldwide and, on the Basque coast (southeastern Bay of Biscay) in particular, there is a recent interest in implementing bivalve aquaculture in open marine waters. In this context, the study of phytoplankton is essential given that it is the main source of energy for bivalves an...

The genus Skeletonema is frequently found in the Bilbao estuary (Northern Spain) where it is broadly distributed along the salinity gradient. By means of morphological and molecular analyses, six strains belonging to three species, Skeletonema costatum, Skeletonema dohrnii and Skeletonema menzelii, have been identified. To know if they can grow act...

The genus Prymnesium includes several species that produce toxins with cytotoxic, ichthyotoxic, neurotoxic and haemolytic activity. Bloom episodes of Prymnesium species have been reported from several parts of the world (North America, Europe, Africa, Asia and Australia), especially from temperate and subtropical regions and most of them from brack...

World aquaculture has undergone a great development in the last decades. In Basque coastal waters in particular, there is an increasing interest in implementing bivalve offshore aquaculture. For filter-feeding bivalves phytoplankton constitutes the main source of energy. Nevertheless, some phytoplankton species are considered harmful due to its pot...

Heterosigma akashiwo is one of the smallest raphidophytes and is known for its ability to form dense, fishkilling blooms. In many parts of the world, H. akashiwo is a permanent resident of the algal community, and blooms have caused extensive financial losses for the aquaculture industry. Different aspects of its biology have been the focus of nume...

Estuarine and marine ecosystems are subject to different sources of stress including changes in environmental physicochemical variables (nutrients, oxygen availability, temperature, salinity, pH) or exposure to a large cocktail of environmental pollutants. In the estuary of Bilbao, despite the improvement in environmental quality due to replacement...

Blooms of centric diatoms are a common feature in the Bilbao estuary during summer when river flow is at its lowest and water temperature is above 20ºC. To gain insight into the specific composition of these diatom blooms, net samples and cultures of estuarine isolates were analysed under the scanning electron microscope (SEM) and by molecular anal...

Seven scale-bearing species of prasinophy-ceans (Chlorophyta) were studied in light and electron microscopy, pigment analysis, and molecular analysis of the small subunit (SSU) rDNA. Unialgal cultures were obtained from samples collected in the Nervión River estu-ary, Gulf of Biscay, Spanish Atlantic coast. Five of the spe-cies belong to the genus...

The dinoflagellate Alexandrium minutum and the haptophyte Prymnesium parvum are well known for their toxin production and negative effects in marine coastal environments. A. minutum produces toxins which cause paralytic shellfish poisoning in humans and can affect copepods, shellfish and other marine organisms. Toxins of P. parvum are associated wi...

The genus Pseudo-nitzschia contains potentially toxic species of problematic taxonomy, making it one of the most intensively studied diatom genera. The study of 35 clonal strains isolated from the Bilbao estuary, an area that experiences recurrent blooms of Pseudo-nitzschia, revealed the presence of two new species, P. abrensis and P. plurisecta, d...

The implementation of water quality European Directives requires an intensification of water quality monitoring, within the limits of the Exclusive Economic Zone. Remote sensing technologies can provide a valuable tool for frequent, synoptic, water-quality observations, over large areas. The aim of this study is to assess the ecological status of B...

Inverted microscopy is widespread employed for the analysis of phytoplankton composition within water quality monitoring networks. However, the analysis at the lowest taxonomical level is not always required for ecological status assessment. In addition, inverted microscopy can underestimate the small phytoplankton, and not always distinguish photo...

Eutrophication is a major threat to coastal ecosystems. Within Europe, the Water Framework Directive (WFD) has established the need of developing methods of assessment. Bulk chlorophyll “a” is used world-wide as an indicator of eutrophication. However, the size structure of the phytoplankton communities has not been investigated, in detail, in rela...

Ten species of the genus Pseudo-nitzschia were identified in the Nervion River estuary from preserved net tow samples and 31 strains isolated from the estuary. Species identification was performed by means of ultrastructural analysis of valve ornamentation and genetic analysis of selected strains of the P. delicatissima complex. Identified species...

The variation in growth of six strains of the fish-killer raphydophyte Heterosigma akashiwo, from different geographic areas, was studied, as a function of salinity (5, 20 and 35 psu), irradiance (40 and 100 mol m -2 s -1) and temperature (17 and 23°C). Two of the strains were isolated from the Nervion River outer estuary (Bilbao, Bay of Biscay, No...

Eleven haptophyte species were isolated over a two year period (2001–2002) from the Nervion River estuary (Biscay Bay) and batch cultured under non-axenic, isothermal (18 °C), isohaline (30 psu) conditions at three different light levels (60, 110 and 350 µmol photons m− 2 s− 1). The variation pattern of growth rate with light intensity was differen...

A marine haptophyte flagellate, Chrysochromulina palpebralis sp. nov., is described from cultures originating from the Nervió n River estuary in the Cantabrian Sea, northern Spain. In addition, cultures of similar organisms originating from Japanese and South African waters have been studied. Cells of C. palpebralis had an ovoid shape with an anter...

The meso-macrotidal Nervion River estuary in northern Spain was sampled monthly from March to September 2002 and 2003 to study species composition and abundance of haptophytes in the phytoplankton. From natural samples and uni-algal cultures, 17 haptophyte species were identified using light and electron microscopy. The species were found across a...

This contribution focuses upon the use of phytoplankton as an indicator of ecological quality in the coastal waters of the Basque Country (Bay of Biscay, northern Spain). The Water Framework Directive (WFD) establishes a common water policy in the European Union. The phytoplankton, owing to its relationship with the eutrophication processes, is one...

Pigment analysis complemented with microscopic observations of live and preserved cells was used to gain insight into the composition of estuarine phytoplankton. Biological material, obtained from the Nervion River estuary, consisted of 37 species belonging to 15 phytoplankton classes and 10 field samples taken in 2004 in the context of a monitorin...

In the context of a monitoring program developed in the Nervion River estuary, the structure of the phytoplankton community was assessed by means of microscopy and high-performance liquid chromatography (HPLC) analysis of pigments. Four size fractions were considered: <3 μm (picoplankton), 3–8 μm (small nanoplankton), 8–20 μm (large nanoplankton) a...

In the Nervion River estuary surface samples were taken from March to September 2003 at six sites covering most of the salinity range with the aim to know the biomass and taxonomic composition of phytoplankton assemblages in the different segments. Nine groups of algae including cyanobacteria, diatoms, dinoflagellates, chlorophytes, prasinophytes,...