Phytoplankton community composition in relation to environmental variability in the Urdaibai estuary (SE Bay of Biscay): Microscopy and eDNA metabarcoding

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 environmental conditions of the estuary, and to compare the two methods used. Diatoms Minutocellus polymorphus and Chaetoceros tenuissimus dominated the outer estuary, being replaced by Teleaulax acuta (cryptophyte), Kryptoperidinium foliaceum (dinoflagellate) and Cyclotella spp. (diatom) towards the inner area. This change was mainly prompted by salinity and nutrients. Metabarcoding revealed the presence of 223 species that were not observed by microscopy in previous studies in the estuary. However, several characteristic species (e.g., K. foliaceum) were only detected with microscopy. Additionally, microscopy covered the limitations of eDNA metabarcoding concerning quantification. Thus, to give a full insight, a combination of techniques is recommended.This research was supported in part through computational resources provided by IMBBC (Institute of Marine Biology, Biotechnology and Aquaculture) of the HCMR (Hellenic Centre of Marine Research). Funding for establishing the IMBBC HPC has been received by the MARBIGEN (EU Regpot) project, LifeWatchGreece RI and the CMBR (Center for the study and sustainable exploitation of Marine Biological Resources) RI. In addition, this study was partially supported by the project PPG17/67 funded by the University of the Basque Country (UPV/EHU) and J. Bilbao was funded by a grant from the University of the Basque Country (UPV/EHU – PIF 18/306). This paper is contribution number 1181 from AZTI (Marine Research Division)

Evaluation of algaecide effectiveness of five different oxidants applied on harmful phytoplankton

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 emerging biocides, including H2O2, peracetic acid (PAA), peroxymonosulfate (PMS), and peroxydisulfate (PDS). The effectiveness of these biocides is compared with that of conventional chlorination methods. Their effects on two ichthyotoxic microalgae with worldwide distribution, i.e., Prymnesium parvum and Heterosigma akashiwo, are examined. To ensure the prolonged effectiveness of the different reagents, their concentration–response curves for 14 days are constructed and examined. The results suggest a strong but shorter effect by PMS (EC50 = 0.40–1.99 mg·L-1) and PAA (EC50 = 0.32–2.70 mg·L-1), a maintained effect by H2O2 (EC50 = 6.67–7.08 mg·L-1), and a negligible effect by PDS. H. akashiwo indicates higher resistance than P. parvum, except when H2O2 is used. Based on the growth inhibition performance and consumption of the reagents as well as a review of important aspects regarding their application, using H2O2, PAA, or PMS can be a feasible alternative to chlorine-based reagents for inhibiting the growth of harmful phytoplankton.This work has been co-funded by the 2014–2020 ERDF Operational Programme and by the Department of Economy, Knowledge, Business and University of the Regional Government of Andalusia (Spain). Project Ref.: FEDER-UCA18–108023. This work is part of the project TED2021–130994B-C31; TED2021–130994B-C33 and Grant IJC2020–042741-I funded by MCIN/AEI/10.13039/501100011033 and by the European Union NextGenerationEU/PRTR

Inhomogeneity detection in phytoplankton time series using multivariate analyses

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 with these aspects are not well-documented. Hence, a long time series (2003-2015) from the Basque continental shelf (southeastern Bay of Biscay) was analyzed to evaluate the uncertainty given by laboratory strategies when studying phytoplankton variability. Variability in phytoplankton communities was explained not only by environmental conditions but also by changes in fixatives (glutaraldehyde and acidic Lugol's solution) and laboratory staff. Based on Bray-Curtis distances, phytoplankton assemblages were found to be significantly dissimilar according to the effect of changes in the specialist handling the sample and the employed fixative. The pair-wise permutational multivariate analysis of variance (PERMANOVA) showed significant differences between the two fixatives utilized and also between the three taxonomists involved. Thus, laboratory-related effects should be considered in the study of phytoplankton time series.The data for this study were obtained from the project "Program for the monitoring and assessment of the ecological status of transitional and coastal waters of the Basque Country" funded by URA, the Basque Water Agency, through a convention with AZTI. This work was supported by the project "IM17MUSSELS". The participation of O. Muniz was funded by a grant from the Department of Economic Development and Competitiveness of the Basque Government (BOPV num. 201; 2013/4467). This paper is contribution number 956 from AZTI (Marine Research Division). We also thank Proof-Reading-Service for their great professional proof reading and editing service, as well as the anonymous reviewers for their comments and suggestions

Assessment of a Sheltered Euhaline Area of the Southeastern Bay of Biscay to Sustain Bivalve Production in Terms of Phytoplankton Community Composition

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 2017, in the Mutriku port, with the main aim of assessing the suitability of the phytoplankton community as a food resource for bivalves. The water column in Mutriku showed the typical environmental conditions of Basque marine waters, with no significant nutrient enrichment caused by anthropogenic pressures. Haptophytes represented the greatest contribution to cell abundance (31-47%), and diatoms were the dominant group in terms of biomass (52-79%),which could favour mussel growth due to their high fatty acid content. In addition, the size structure of the phytoplankton community was suitable for mussel ingestion, since the predominant cell size was 2-20 mu m. Regarding toxic phytoplankton, the genera that pose a risk for human health and those that affect negatively mussel physiology and survival were considered. Altogether, ten toxic phytoplankton taxa were identified, contributing in less than 5% to the total cell abundance of Mutriku. However, median chlorophyll a concentration was low (0.5 mu g L-1), reflecting the oligotrophic conditions of the area. Therefore, even if the composition of the phytoplankton community could be favourable for bivalve aquaculture, biomass values are low compared to other zones of bivalve productionThis study was partially supported by the project EGRECOST CALIDAD -Control de Calidad de Aguas Cultivos Marinos (Departamento de Desarrollo Economico e Infraestructuras del Gobierno Vasco) and the project PPG17/67 funded by the University of the Basque Country (UPV/EHU). J. Bilbao was funded by a grant from the University of the Basque Country (UPV/EHU -PIF 18/306). This paper is contribution number 991 from AZTI (Marine Research Division

Anianabacter salinae gen. nov., sp. nov. ASV31T, a Facultative Alkaliphilic and Extremely Halotolerant Bacterium Isolated from Brine of a Millennial Continental Saltern

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-motile bacterium that formed beige-to-pink colonies on marine agar. According to a 16S rRNA gene-based phylogenetic analysis, strain ASV31T forms a distinct branch of the family Rhodobacteraceae, with Thioclava pacifica DSM 10166T being its closest type strain (95.3%). This was confirmed with a phylogenomic tree and the values of ANI (73.9%), dDDH (19.3%), AAI (63.5%) and POCP (56.0%), which were below the genus/species level boundary. Additionally, an ability to degrade aromatic compounds and biosynthesise secondary metabolites was suggested by the genome of strain ASV31T. Distinguishing fatty acid profiles and polar lipid content were also observed. The genome size was 3.6 Mbp, with a DNA G+C content of 65.7%. Based on the data obtained, it was considered that strain ASV31T (=CECT 30309T = LMG 32242T) represents a new species of a new genus in the family Rhodobacteraceae, for which the name Anianabacter salinae gen. nov., sp. nov. is proposed.This research was funded by the University of the Basque Country UPV/EHU (grant number US19/01) and the Añana Salt Valley Foundation (specific agreement between the Añana Salt Valley Foundation and the University of the Basque Country UPV/EHU)

Data on the Amphidinium Carterae Dn241EHU Isolation and Morphological and Molecular Characterization

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 morphological characterization was made using two different techniques of microscopy and the molecular characterization by using the 28S rDNA sequences of D1 and D2 domains. This strain has been used for a culture study in an indoor LED-lighted pilot-scale raceway to determine its production of carotenoids and fatty acids, "Long-term culture of the marine dinoflagellate microalga Amphidinium carterae in an indoor LED-lighted raceway photobioreactor: Production of carotenoids and fatty acids." (Molina-Miras et al., 2018) [1]. (C) 2018 The Authors. Published by Elsevier Inc.This research was funded by the Spanish Ministry of Economy and Competitiveness (CTQ2014-55888-C3-02), the European Regional Development Fund Program, and the projects PPG17/67 from the UPV/EHU and IT1040-16 from the Basque Government

Bioactives Overproduction through Operational Strategies in the Ichthyotoxic Microalga Heterosigma akashiwo Culture

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 artificially illuminated with multi-coloured LED lights. Growth and production of exopolysaccharides, polyunsaturated fatty acids (PUFAs), and carotenoids were evaluated under different culture modes (batch, fed-batch, semicontinuous, and continuous) at two irradiance levels (300 and 700 µE·s−1·m−2). Continuous mode at the dilution rate of 0.2·day−1 and 700 µE·s−1·m−2 provided the highest production of biomass, PUFAs (132.6 and 2.3 mg·L−1·day−1), and maximum fucoxanthin productivity (0.16 mg·L−1·day−1). The fed-batch mode accumulated exopolysaccharides in a concentration (1.02 g·L−1) 10-fold over the batch mode. An extraction process based on a sequential gradient partition with water and four water-immiscible organic solvents allowed the isolation of bioactive fucoxanthin from methanolic extracts of H. akashiwo. Metabolites present in H. akashiwo, fucoxanthin and polar lipids (i.e., eicosapentaenoic acid (EPA)), or probably such as phytosterol (β-Sitosterol) from other microalgae, were responsible for the antitumor activity obtained.This research was funded by the General Secretariat of Universities, Research and Technology of the Andalusian Government (grant: P18-RT-2477) and the State Research Agency (grants PID2019-109476RB-C22) of the Spanish Ministry of Science, Innovation and Universities

Euskal kostaldeko fitoplanktona eta bere garrantzia bibalbioen akuikulturan

Lately, aquaculture has undergone a great development worldwide and, in the Basque Country, there is an increasing interest for developing it. Nowadays, there is an offshore aquaculture site in Mendexa, which started producing mussels recently. Alternative locations have been discussed to continue developing the sector, such as the port of Mutriku. In this context, studying the phytoplankton community is essential, since it is the main source of energy for bivalves and the main potential toxicity risk. In the last years, several studies on the suitability of the phytoplankton communities from Mendexa and Mutriku as a food resource for bivalves have been carried out. For that, phytoplankton community composition and biomass were analyzed, paying special attention to toxic taxa and concentrations of toxins in mussel flesh. Diatoms and haptophytes, together with dinoflagellates, were the most important groups at both stations in terms of abundance and/or biomass, which could favor mussel growth due to high fatty acid content. Moreover, the predominant cell size of the comunities (2-20 μm) would enable an efficient ingestion and retention for mussels. However, chlorophyll a waslow at both sites comparing with other aquaculture areas in Europe, with an average concentration of 0.5 μg/L approximately. Regarding shellfish toxicity, alert limits were exceeded several times, being Dinophysis the most compromising genus for Basque aquaculture, especially in Mendexa, where higher cell abundances and toxin concentrations (okadaic acid) of this genus were recorded. Consequently, the phytoplankton monitoring should be carefully conducted in order to detect possible toxicity risks.; Akuikulturak azken hamarkadan mundu mailan izan duen garapena itzela izan da, eta horrek Euskal Autonomia Erkidegoan (EAEn) moluskuen akuikultura gauzatzeko nahia piztu du. Gaur egun, muskuiluak ekoizten berriki hasi den akuikultura-eremu bakarra dago EAEn, itsaso zabalean, Mendexako kostaldearen aurrean. Hala ere, sektorea gehiago garatzeko helburuz, beste aukerazko kokaleku batzuk planteatu dira, Mutrikuko portua adibidez. Gauzak horrela, ezinbestekoa da eremu horretako fitoplanktonaren azterketa sakona egitea, bibalbioen energia-iturri eta, aldi berean, gizakiongan toxikotasun-eragile nagusia baita. Azken urteotan, Mendexan eta Mutrikun, bibalbioen akuikulturarekin erlazionatutako fitoplanktonaren zenbait ikerketa gauzatu dira, bertako komunitate naturalek bibalbioen akuikulturari eusteko duten egokitasuna ezagutzeko asmoz. Ikerketa horietan fitoplankton-komunitatearen ugaritasuna eta osaketa aztertu ziren, potentzialki toxikoak ziren taxonei arreta berezia eskainiz. Horrez gain, muskuiluen haragian aurkitutako toxina-kontzentrazioa ere neurtu zen. Diatomeoak eta haptofitoak izan ziren Mendexako eta Mutrikuko komunitate fitoplanktonikoen talde nagusiak, dinoflagelatuen aldizkako agerpenekin batera. Horrenbestez, fitoplankton-komunitate horiek muskuiluen hazkuntzarako kalitate nutrizional onuragarria daukatela ikusi da, talde nagusiek gantz azido maila altuak azaltzen dituztelako. Gainera, komunitateetan nagusitzen zen zelula-tamaina (2-20 μm) aproposa da muskuiluen ingestio eta erretentzio eraginkorrerako. Hala ere, Europako beste akuikultura eremu batzuekin alderatuz, Mendexako eta Mutrikuko a klorofila-balioak oso baxuak dira, 0,5 μg/L inguruko kontzentrazioekin. Halaber, itsaskien toxikotasun-arriskua adierazten duten zelula-ugaritasuna eta toxinen kontzentrazio-mugak hainbat aldiz gainditu ziren bi eremuetan. Dinophysis da generorik arriskutsuena, Mendexan bereziki, genero horren eta bere toxinen (azido okadaikoa) kontzentrazioa handiagoa baita. Horrenbestez, beharrezkoa da fitoplanktonen azterketekin jarraitzea, toxikotasun-arrisku posibleak hauteman eta kontrolatzeko

The Expanded mtDNA Phylogeny of the Franco-Cantabrian Region Upholds the Pre-Neolithic Genetic Substrate of Basques

The European genetic landscape has been shaped by several human migrations occurred since Paleolithic times. The accumulation of archaeological records and the concordance of different lines of genetic evidence during the last two decades have triggered an interesting debate concerning the role of ancient settlers from the Franco-Cantabrian region in the postglacial resettlement of Europe. Among the Franco-Cantabrian populations, Basques are regarded as one of the oldest and more intriguing human groups of Europe. Recent data on complete mitochondrial DNA genomes focused on macrohaplogroup R0 revealed that Basques harbor some autochthonous lineages, suggesting a genetic continuity since pre-Neolithic times. However, excluding haplogroup H, the most representative lineage of macrohaplogroup R0, the majority of maternal lineages of this area remains virtually unexplored, so that further refinement of the mtDNA phylogeny based on analyses at the highest level of resolution is crucial for a better understanding of the European prehistory. We thus explored the maternal ancestry of 548 autochthonous individuals from various Franco-Cantabrian populations and sequenced 76 mitogenomes of the most representative lineages. Interestingly, we identified three mtDNA haplogroups, U5b1f, J1c5c1 and V22, that proved to be representative of Franco-Cantabria, notably of the Basque population. The seclusion and diversity of these female genetic lineages support a local origin in the Franco-Cantabrian area during the Mesolithic of southwestern Europe, ∼10,000 years before present (YBP), with signals of expansions at ∼3,500 YBP. These findings provide robust evidence of a partial genetic continuity between contemporary autochthonous populations from the Franco-Cantabrian region, specifically the Basques, and Paleolithic/Mesolithic hunter-gatherer groups. Furthermore, our results raise the current proportion (≈15%) of the Franco-Cantabrian maternal gene pool with a putative pre-Neolithic origin to ≈35%, further supporting the notion of a predominant Paleolithic genetic substrate in extant European populations