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The holoplanktonic mollusks (Mollusca, Pteropoda and Pterotrachoidea) are independent and key groups of organisms in any marine ecosystem due to the role they play in the carbon and energy transfer along the marine trophic webs. We document the species of holoplanktonic mollusks collected in the surface waters (10 m depth) during an oceanographic expedition in the Campeche Canyon, southern Gulf of Mexico, during the February 2011 winter storm (“Nortes”) season. Organisms were collected using a close/open/close net system. Eighteen species belonging to 12 genera and nine families of pteropods were identified. Three species of Pterotrachoidea were identified. Limacina trochiformis (d’Orbigny, 1835), Heliconoides inflatus (d’Orbigny, 1835), and Creseis conica (Eschscholtz, 1829) were the species with highest density values (600.3, 678.5, and 746.8 ind · 100 m−3, respectively). The results presented here contribute to the knowledge of this group of organisms in oceanic waters of the southern Gulf of Mexico, especially during a time of year where observations are scarce.

Although metabarcoding is a well-established tool for describing diversity of pelagic communities, its quantitative value is still controversial, with poor correlations previously reported between organism abundance/biomass and sequence reads. In this study, we explored an enhanced quantitative approach by metabarcoding whole zooplankton communities using a highly degenerate primer set for the mitochondrial marker cytochrome oxidase I and compared the results to biomass estimates obtained using the traditional morphological approach of processing zooplankton samples. As expected, detected species richness using the metabarcoding approach was 3–4 times higher compared to morphological processing, with the highest differences found in the meroplankton fraction. About 75% of the species identified using microscopy were also recovered in the metabarcoding run. Within the taxa detected using both approaches, the relative numbers of sequence counts showed a strong quantitative relationship to their relative biomass, estimated from length-weight regressions, for a wide range of metazoan taxa. The highest correlations were found for crustaceans and the lowest for meroplanktonic larvae. Our results show that the reported approach of using a metabarcoding marker with improved taxonomic resolution, universal coverage for metazoans, reduced primer bias, and availability of a comprehensive reference database, allow for rapid and relatively inexpensive processing of hundreds of samples at a higher taxonomic resolution than traditional zooplankton sorting. The described approach can therefore be widely applied for monitoring or ecological studies.

Linezolid is a last-resort antibiotic for the treatment of severe infections caused by multidrug-resistant Gram-positive organisms; although linezolid resistance remains uncommon, the number of linezolid-resistant enterococci has increased in recent years due to worldwide spread of acquired resistance genes (cfr, optrA, and poxtA) in clinical, animal, and environmental settings. In this study, we investigated the occurrence of linezolid-resistant enterococci in marine samples from two coastal areas in Italy. Isolates grown on florfenicol-supplemented Slanetz-Bartley agar plates were investigated for their carriage of optrA, poxtA, and cfr genes; optrA was found in one Enterococcus faecalis isolate, poxtA was found in three Enterococcus faecium isolates and two Enterococcus hirae isolates, and cfr was not found. Two of the three poxtA-carrying E. faecium isolates and the two E. hirae isolates showed related pulsed-field gel electrophoresis (PFGE) profiles. Two E. faecium isolates belonged to the new sequence type 1710, which clustered in clonal complex 94, encompassing nosocomial strains. S1 PFGE/hybridization assays showed a double (chromosome and plasmid) location of poxtA and a plasmid location of optrA. Whole-genome sequencing revealed that poxtA was contained in a Tn6657-like element carried by two plasmids (pEfm-EF3 and pEh-GE2) of similar size, found in different species, and that poxtA was flanked by two copies of IS1216 in both plasmids. In mating experiments, all but one strain (E. faecalis EN3) were able to transfer the poxtA gene to E. faecium 64/3. The occurrence of linezolid resistance genes in enterococci from marine samples is of great concern and highlights the need to improve practices aimed at limiting the transmission of linezolid-resistant strains to humans from environmental reservoirs. IMPORTANCE Linezolid is one of the few antimicrobials available to treat severe infections due to drug-resistant Gram-positive bacteria; therefore, the emergence of linezolid-resistant enterococci carrying transferable resistance determinants is of great concern for public health. Linezolid resistance genes (cfr, optrA, and poxtA), often plasmid located, can be transmitted via horizontal gene transfer and have the potential to spread globally. This study highlights the detection of enterococci carrying linezolid resistance genes from sediment and zooplankton samples from two coastal urban areas in Italy. The presence of clinically relevant resistant bacteria, such as linezolid-resistant enterococci, in marine environments could reflect their spillover from human and/or animal reservoirs and could indicate that coastal seawaters also might represent a source of these resistance genes.

L'evolució dels animals ha fascinat investigadors de molts camps des que Charles Darwin va proposar la teoria de la selecció natural. En un dels passatges del seu llibre parla de la importància del desenvolupament embrionari per a l'evolució, perquè durant aquest període es formen les estructures dels organismes adults. El que no va poder explicar era de quina manera es produeixen els canvis sobre els quals actua la selecció natural. Ara sabem que el material genètic conté les instruccions perquè els organismes es formin, per la qual cosa els canvis o mutacions en el DNA són la font de les innovacions evolutives. De manera intuïtiva pot semblar que els organismes complexos han de tenir més gens. Actualment se sap que la complexitat no depèn tant del nombre de gens com de la manera com se'n regula el funcionament. El que poques persones sospitarien és que, de vegades, la pèrdua de gens pot implicar un increment de complexitat evolutiva. Això és el que han demostrat Cristian Cañestro i els seus col·laboradors, del grup de recerca en evolució i desenvolupament (Evo-Devo) de la Universitat de Barcelona. Han descobert que una sèrie de pèrdues gèniques sobtades va alliberar un grup d'animals sèssils, que vivien enganxats al fons marí, d'aquesta dependència, i van esdevenir organismes de vida lliure. Segons afirmen a l'article que la revista Nature ha destacat a la portada, aquest fet ha introduït un tomb important en la visió evolutiva que fins ara es tenia de l'origen del nostre llinatge, i al mateix temps ha obert la porta a noves recerques biomèdiques.

Although metazoan animals in the mesopelagic zone play critical roles in deep pelagic food webs and in the attenuation of carbon in midwaters, the diversity of these assemblages is not fully known. A metabarcoding survey of mesozooplankton diversity across the epipelagic, mesopelagic and upper bathypelagic zones (0–1500 m) in the North Pacific Subtropical Gyre revealed far higher estimates of species richness than expected given prior morphology-based studies in the region (4,024 OTUs, 10-fold increase), despite conservative bioinformatic processing. Operational taxonomic unit (OTU) richness of the full assemblage peaked at lower epipelagic–upper mesopelagic depths (100–300 m), with slight shoaling of maximal richness at night due to diel vertical migration, in contrast to expectations of a deep mesopelagic diversity maximum as reported for several plankton groups in early systematic and zoogeographic studies. Four distinct depth-stratified species assemblages were identified, with faunal transitions occurring at 100 m, 300 m and 500 m. Highest diversity occurred in the smallest zooplankton size fractions (0.2–0.5 mm), which had significantly lower % OTUs classified due to poor representation in reference databases, suggesting a deep reservoir of poorly understood diversity in the smallest metazoan animals. A diverse meroplankton assemblage also was detected (350 OTUs), including larvae of both shallow and deep living benthic species. Our results provide some of the first insights into the hidden diversity present in zooplankton assemblages in midwaters, and a molecular reappraisal of vertical gradients in species richness, depth distributions and community composition for the full zooplankton assemblage across the epipelagic, mesopelagic and upper bathypelagic zones. Fil: Sommer, Stephanie A.. University of Hawaii at Manoa; Estados Unidos Fil: Van Woudenberg, Lauren. University of Hawaii at Manoa; Estados Unidos Fil: Lenz, Petra H.. University of Hawaii at Manoa; Estados Unidos Fil: Cepeda, Georgina Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Subsede Instituto Nacional de Investigación y Desarrollo Pesquero; Argentina Fil: Goetze, Erica. University of Hawaii at Manoa; Estados Unidos

Memoria de tesis doctoral presentada por Anna Arias Bulbena para obtener el título de Doctora en Ciencias Marinas por la Universitat de Barcelona (UB), realizada bajo la dirección del Dr. Albert Calbet Fabregat y del Dr. Enric Saiz Sendrós del Institut de Ciències del Mar (ICM-CSIC).-- 201 pages, figures, tables, supplementary material, annexes, [EN] Protistan grazers are a key component of marine planktonic food webs. These marine protists are the major grazers of pelagic primary production in the oceans and, therefore, they display a crucial role in marine biogeochemical cycles as pivotal intermediaries of the energy and mass flux from primary producers to higher trophic levels. Notwithstanding their relevant role in the global pelagic system, some key aspects related to their trophic behaviour remain still poorly understood. Among these features, diel feeding rhythms are of relevant importance as they represent the coupling between the cycles of primary production and the feeding cycles of their predators and, consequently, they strongly condition the carbon flux mediated by marine protistan grazers and the dynamics of planktonic food webs. This Ph.D. Thesis aims to deepen our knowledge of the diel feeding rhythms in marine protistan grazers, exploring their occurrence and the mechanisms that generate and modulate this rhythmic behaviour. Accordingly, we first investigated the existence of diel feeding rhythms in diverse species of heterotrophic and mixotrophic protistan grazers (the dinoflagellates Gyrodinium dominans, Oxyrrhis marina and Karlodinium armiger, and the ciliates Strombidium arenicola and Mesodinium rubrum). Then, we evaluated how intrinsic characteristics of the prey (Rhodomonas salina), including the growth phase and the diel variations on its stoichiometric composition, as well as own characteristics of the grazers, such as their previous feeding history and the timing for cell division, may be causal factors or perhaps regulate the diel feeding activity of marine protists. We also assessed the effect of extrinsic factors, such as the prey concentration, the light and the risk of predation, on the feeding rhythm of marine protists. Finally, we conducted field experimentation to study the diel feeding rhythms of protistan grazers in a natural ecosystem, the Gullmar Fjord (Sweden). As major conclusions of the present Ph.D. Thesis, we found that there might not exist a unique underlying mechanism causing the different patterns of diel feeding rhythms we observed in marine protistan grazers. Instead, it appears that marine protists species might have developed feeding rhythms largely conditioned by their physiological and behavioural characteristics, as well as by the ecological conditions from their original habitat, which might determine the factors by which it is modulated, [ES] Los ramoneadores protistas son un componente clave de las redes tróficas planctónicas marinas. Estos protistas marinos son los principales consumidores de producción primaria pelágica en los océanos y presentan, por lo tanto, un papel crucial en los ciclos biogeoquímicos marinos como intermediarios fundamentales de los flujos de energía y masa desde los productores primarios hacia niveles tróficos superiores. A pesar de su relevante papel en el sistema pelágico global, algunos aspectos clave relacionados con su comportamiento trófico son todavía poco conocidos. Entre estas características, los ritmos diarios de alimentación son de gran importancia, ya que representan el acoplamiento entre los ciclos de producción primaria y los ciclos de alimentación de sus depredadores y, en consecuencia, condicionan en gran medida el flujo de carbono mediado por los ramoneadores protistas marinos y la dinámica de las redes alimentarias planctónicas. Esta Tesis Doctoral tiene como objetivo profundizar en nuestro conocimiento de los ritmos de alimentación en los ramoneadores protistas marinos, estudiando su ocurrencia y los mecanismos que generan y modulan este comportamiento rítmico. Por ello, primeramente investigamos la presencia de ritmos diarios de alimentación en diversas especies de ramoneadores protistas heterotróficos y mixótrofos (los dinoflagelados Gyrodinium dominans, Oxyrrhis marina y Karlodinium armiger, y los ciliados Strombidium arenicola y Mesodinium rubrum). Luego, evaluamos como características intrínsecas de la presa (Rhodomonas salina), como son su fase de crecimiento y las variaciones diarias en su composición estequiométrica, así como también características propias de los ramoneadores, tales como su historia de alimentación previa y el momento de división celular, pueden ser factores causantes o bien reguladores de los ritmos diarios de alimentación en los protistas marinos. También investigamos el efecto de factores extrínsecos, como son la concentración de presas, la luz y el riesgo de depredación, sobre la actividad de alimentación rítmica de los protistas marinos. Finalmente, realizamos un estudio de campo sobre los ritmos de alimentación diarios de los ramoneadores protistas en un ecosistema natural, el Fiordo de Gullmar (Suecia). Como conclusiones principales de la presente Tesis Doctoral, encontramos que quizás no exista un mecanismo causal único que explique los diferentes patrones de ritmos diarios de alimentación en los ramoneadores protistas marinos. Nuestro estudio parece indicar que las especies de protistas marinos desarrollan ritmos diarios de alimentación condicionados, en gran medida, por sus características fisiológicas y de comportamiento, además de por las particularidades ecológicas de su hábitat de origen, las cuales determinarían los factores por los que este patrón de actividad puede ser modulado, [CAT] Els pastors protistes són un component clau de les xarxes alimentàries planctòniques marines. Aquests protistes marins constitueix el principal consumidor de la producció primària pelàgica en els oceans i presenta, per tant, un paper crucial en els cicles biogeoquímics marins com intermediaris fonamentals en els fluxos d'energia i de massa des dels productors primaris cap a nivells tròfics superiors. Tot i el seu rol rellevant en el sistema pelàgic global, alguns aspectes clau relacionats amb el seu comportament tròfic són encara poc coneguts. Entre aquestes característiques, els ritmes diaris d'alimentació són de gran importància, ja que representen l'acoblament entre els cicles de producció primària i els cicles d'alimentació dels seus depredadors i, en conseqüència, condicionen en gran manera el flux de carboni mediat pels pastors protistes marins i la dinàmica de la xarxa alimentaria planctònica. Aquesta Tesi Doctoral té com a objectiu aprofundir en el nostre coneixement sobre els ritmes d’alimentació diaris en els pastors protistes marins, estudiant la seva presencia i els mecanismes que generen i modulen aquest comportament rítmic. Així doncs, primerament vam investigar l’existència de ritmes diaris d’alimentació en diverses espècies de pastors protistes heterotròfics i mixòtrofs (els dinoflagel·lats Gyrodinium dominans, Oxyrrhis marina, i Karlodinium armiger, i els ciliats Strombidium arenicola i Mesodinium rubrum). Llavors, vam avaluar com característiques intrínseques de la presa (Rhodomonas salina), com són la fase de creixement i les variacions diàries en la seva composició estequiomètrica, així com també característiques pròpies dels pastors, com la seva història d’alimentació prèvia i el moment de divisió cel·lular, poden ser factors causants o bé reguladors dels ritmes diaris d’alimentació dels protistes marins. També vam avaluar l’efecte de factors extrínsecs, com són la concentració de presa, la llum i el risc de depredació, en l’activitat d’alimentació rítmica dels protistes marins. Finalment, vam portar a terme un estudi de camp per explorar els ritmes d’alimentació dels pastors protistes en un ecosistema natural (el Fiord de Gullmar, Suècia). Com a conclusions principals de la present Tesi Doctoral, vam trobar que potser no existeix un mecanisme causant únic dels ritmes diaris d’alimentació en pastors protistes marins. El nostre estudi sembla indicar que les espècies de protistes marins desenvolupen ritmes d’alimentació condicionats, en gran manera, per les seves característiques fisiològiques i de comportament, així com també de les particularitats ecològiques del seu hàbitat d’origen, les quals determinarien els factors pels quals el ritme és modulat, The present Ph.D. Thesis was carried out at the Institut de Ciències del Mar (CSIC) and it was developed in the framework of the FERMI project (CGL2014-59227-R). The author was financed by an FPI predoctoral fellowship (BES-2015-074092) funded by the Spanish Ministry of Science and Innovation (MICINN)

Some holoplanktonic polychaetes (Annelida: Polychaeta) from the Parque Nacional Isla del Coco, Costa Rica. The holoplanktonic polychaetes have not been surveyed in the oceanic waters adjacent to Isla del Coco. These pelagic forms are studied based on the analysis of zooplankton samples collected in the area. Samples were obtained both at night and daytime by standard plankton nets (0.2-0.5 mm meshes, 0.49 m mouth diameter) hauled horizontally and vertically off the oceanic island Isla del Coco, Costa Rica in the Eastern Tropical Pacific. Pelagic polychaetes were collected in one of the night samples and were taxonomically analyzed. The material obtained includes representatives of six species and five families: Alciopidae, Lopadorrhynchidae, Tomopteridae, Polynoidae, and Typhloscolecidae. Brief diagnoses, synonymies, comparative morphological comments, taxonomic illustrations, and data on the distribution of the species collected in the plankton of Isla del Coco are provided. The record of Drieschia pellucida Moore is the first of the species in the Eastern Tropical Pacific; our specimen shows some differences with respect to the original description. The rest of the species have been recorded previously in waters of the Eastern Tropical Pacific, but are the first records of this important protected area. Citation: Jiménez-Cueto, S., E. Suárez-Morales & Á. Morales-Ramírez. 2012. Algunos poliquetos holoplanctónicos (Annelida: Polychaeta) del Parque Nacional de Isla del Coco, Costa Rica. Rev. Biol. Trop. 60 (Suppl. 3): 207-222. Epub 2012 Dec 01. Los poliquetos holoplanctónicos no han sido estudiados en las aguas oceánicas adyacentes al Parque Isla del Coco. Se estudiaron estas formas pelágicas a partir del análisis de muestras de zooplancton recolectadas en esta área protegida. Las muestras fueron obtenidas mediante redes de plancton estándar (0.2-0.5mm de malla, 0.49m de diámetro de boca) en arrastres horizontales y verticales en la isla oceánica Isla del Coco, Costa Rica, en el Pacífico Tropical Oriental. Los poliquetos pelágicos de esta zona fueron analizados taxonómicamente. El material obtenido incluye representantes de seis especies y cinco familias: Alciopidae, Lopadorhynchidae, Tomopteridae, Polynoidae y Typhloscolecidae. Se presentan diagnosis breves, sinonimias, análisis morfológicos comparativos, ilustraciones taxonómicas y la distribución conocida de las especies recolectadas en el plancton de Isla del Coco. El registro de Drieschia pellucida Moore es el primero en el Pacífico Tropical Oriental; nuestro espécimen muestra algunas diferencias respecto a la descripción original. El resto de las especies han sido encontradas previamente en aguas del Pacífico Tropical Oriental y en el Domo de Costa Rica, pero son los primeros registros para esta área protegida.

Poster.-- 2nd Biospecimen Research Symposium: Focus on Quality and Standards, Berlin, February 5-6, 2019, Knowledge of the structure of the zooplankton allows characterizing marine ecosystems and knowing the interactions (connectance and nestedness) that occur in them. Zooplankton responses to environmental variability bring about fundamental changes in the dynamics of marine ecosystems, causing fluctuation in primary production. Many species of zooplankton within the marine environment has also a key role in the transmission of parasites to higher trophic levels. Since 2004, as a part of a large sampling plan for mesozooplankton in a seasonal upwelling system carried out by the lnstitute of Marine Research (IIM-CSIC), a large number of samples were collected for further research projects. The matter raised was if the Fish Parasite Biobank (FPB) Service already established at the IIM-CSIC would turn the challenge posed by monitoring these samples over time into an opportunity to preserve traceable zooplankton samples and their associated data

International audience; Toxicity of polyethylene microplastics (PE-MP) of size ranges similar to their natural food to zooplanktonic organisms representative of the main taxa present in marine plankton, including rotifers, copepods, bivalves, echinoderms and fish, was evaluated. Early life stages (ELS) were prioritized as testing models in order to maximize sensitivity. Treatments included particles spiked with benzophenone-3 (BP-3), a hydrophobic organic chemical used in cosmetics with direct input in coastal areas. Despite documented ingestion of both virgin and BP-3 spiked microplastics no acute toxicity was found at loads orders of magnitude above environmentally relevant concentrations on any of the invertebrate models. In fish tests some effects, including premature or reduced hatching, were observed after 12 d exposure at 10 mg L-1 of BP-3 spiked PE-MP. The results obtained do not support environmentally relevant risk of microplastics on marine zooplankton. Similar approaches testing more hydrophobic chemicals with higher acute toxicity are needed before these conclusions could be extended to other organic pollutants common in marine ecosystems. Therefore, the replacement of these polymers in consumer products must be carefully considered.

We report for the first time the presence of a rare salp Helicosalpa komaii (Ihle and Ihle-Landenberg, 1936) on the west coast of Baja California peninsula (26°52.7' N, 117°09.2' W). The single specimen recorded was a solitary zooid of 200mm length and 90ml of displacement volume. It was recognized by having a distinctive highly convoluted heart-shaped dorsal tubercle. The total number of muscle fibers in the solitary zooid (MI to MVII=517) surpassed that of the other 2 known congeners supporting its identity as H. komaii. H. komaii increases to 29 the total number of salps species reported in coastal and oceanic waters off north-central Baja California (gamma diversity). We hypothesize that the presence of H. komaii in the study area may be the result of onshore intrusions of subtropical waters originating west-southwest of the California Current domain.

Monstrilloid copepods were collected during zooplankton surveys in the Beagle Channel at the southernmost end of South America. These specimens represent two species of Monstrillopsis, one of them undescribed, and one new species of Monstrilla. Monstrillopsis igniterra n. sp. is related to forms of the M. dubia species group, and particularly to M. ferrarii and M. chilensis. It differs from these species in the relative length of the antennules, the shape and relative size of the genital double and anal somites, details of the antennular armature, and the possession of a short inner caudal seta. The other species of Monstrillopsis, M. chilensis, was previously known only from the Southeast Pacific off Chile, and was originally described from female specimens only. Male individuals found in the Beagle Channel are described and assigned herein to this species. These are the first records of Monstrillopsis from high latitudes of South America. The new species Monstrilla patagonica n.sp. is represented by males. It is characterized by the structure and relative size of the genital lappets, details of the antennular structure, armature, relative size and the number (6) of caudal setae. It belongs to a small group of species with highly modified, pectinate male antennules. A female specimen identified as M. helgolandica 35 years ago from southern Argentina is tentatively reidentified as the female of this new species, based on its differences from M. helgolandica and the rarity of this species group in the region.

Monstrilloid copepods were collected during zooplankton surveys in the Beagle Channel at the southernmost end of South America. These specimens represent two species of Monstrillopsis, one of them undescribed, and one new species of Monstrilla. Monstrillopsis igniterra n. sp. is related to forms of the M. dubia species group, and particularly to M. ferrarii and M. chilensis. It differs from these species in the relative length of the antennules, the shape and relative size of the genital double and anal somites, details of the antennular armature, and the possession of a short inner caudal seta. The other species of Monstrillopsis, M. chilensis, was previously known only from the Southeast Pacific off Chile, and was originally described from female specimens only. Male individuals found in the Beagle Channel are described and assigned herein to this species. These are the first records of Monstrillopsis from high latitudes of South America. The new species Monstrilla patagonica n.sp. is represented by males. It is characterized by the structure and relative size of the genital lappets, details of the antennular structure, armature, relative size and the number (6) of caudal setae. It belongs to a small group of species with highly modified, pectinate male antennules. A female specimen identified as M. helgolandica 35 years ago from southern

The main goal of this survey was to study the vertical and horizontal distribution of the thecosome pteropods in the upper 100 m of the western Caribbean Sea. Zooplankton was collected at 60 stations in January 2007 at stratified depth intervals of 25 m from the surface to 100 m. The community was analyzed for diversity, evenness, species richness, and similarity. We recorded 36 taxa 12 of which are new records for the western Caribbean. The most abundant taxa were Limacina inflata, L. trochiformis, Creseis acicula f. clava, Cuvierina columnella atlantica, and Hyalocylis striata. In general, these taxa showed a similar pattern, their highest abundances occurred consistently in 0-25 m layer in both night and day samples; abundance decreased with depth. Significant day/night differences were found in the composition and abundance of pteropods, differences among depth intervals were non-significant. Our results showed that the upper 25 m harbored the highest species richness, diversity, and vertical abundance of pteropods, thus providing unprecedented detail with respect to previous surveys. The local community structure of the pteropods is determined largely by vertical day/night migrations. Pteropods tended to be most abundant in the southern and northern sectors of the area, but highest diversity and species richness were recorded in the central sector. Overall, the low variability of the hydrographic conditions and the mixed horizontal distribution of the clusters from the similarity analysis suggest that day/night migratory patterns of the most abundant taxa are determinant of the observed variability of the pteropod community.

The increasing levels of heavy metals derived from human activity are poisoning marine environments, threating zooplankton and ocean food webs. To protect themselves from the harmful effects of heavy metals, living beings have different physiological mechanisms, one of which is based on metallothioneins (MTs), a group of small cysteine-rich proteins that can bind heavy metals counteracting their toxicity. The MT system of urochordate appendicularians, an ecologically relevant component of the zooplankton, remained, however, unknown. In this work, we have characterized the MTs of the appendicularian species Oikopleura dioica, revealing that O. dioica has two MT genes, named OdMT1 and OdMT2, which encode for Cys-rich proteins, the former with 72 amino acids comparable with the small size MTs of other organisms, but the second with 399 amino acids representing the longest MT reported to date for any living being. Sequence analysis revealed that OdMT2 gene arose from a duplication of an ancestral OdMT1 gene followed by up to six tandem duplications of an ancestral repeat unit (RU) in the current OdMT2 gene. Interestingly, each RU contained, in turn, an internal repeat of a 7-Cys subunit (X3CX3CX2CX2CX3-6CX2CXCX), which is repeated up to 12 times in OdMT2. Finally, ICP-AES analyses of heterologously expressed OdMT proteins showed that both MTs were capable to form metal-complexes, with preference for cadmium ions. Collectively, our results provide the first characterization of the MT system in an appendicularian species as an initial step to understand the zooplankton response to metal toxicity and other environmental stress situations.

Dissertação de Mestrado em Estudos Integrados dos Oceanos. Os ecossistemas de bancos submarinos são considerados de elevada importância uma vez que contém elevada biodiversidade marinha, tendo assim um elevado interesse económico. Este trabalho teve como local de estudo o banco submarino Condor, que se localiza sensivelmente a 10 milhas náuticas a Sudoeste da ilha do Faial. Foram objectivos principais deste estudo caracterizar qualitativamente e quantitativamente as comunidades planctónicas e determinar as suas variações no tempo e no espaço, bem como associar os respectivos padrões de distribuição aos factores físicos e ambientais envolventes. Para esse efeito foram realizados no âmbito do projecto CONDOR (PT0040 co-financiado pelo programa EEA Grants Financial Mechanism - Iceland, Liechtenstein and Norway) sete cruzeiros oceanográficos a bordo do N/I “Arquipélago” entre Março de 2009 e Março de 2010. Recolheram-se um total de 103 amostras de água para análise fitoplanctónica e 110 amostras para determinar a concentração de clorofila a. Obtiveram-se simultaneamente dados de CTD e foi recolhido um total de 59 amostras de zooplâncton. Com o processamento de algumas das respectivas amostras em laboratório, identificaram-se em termos taxonómicos, o fitoplâncton e zooplâncton, bem como, foram estimadas as abundâncias e as biomassas de zooplâncton. O presente trabalho concerne apenas a 7 estações de amostragem biológica/caracterização físico/química da água (versus um total de cerca de 20 estações de amostragem realizados em cada um dos cruzeiros). Os resultados obtidos pelos perfis de CTD revelaram uma coluna de água estratificada no Verão e bastante misturada no Inverno/Primavera, bem como um máximo de oxigénio também em Julho e não em Março como seria de esperar. Os resultados também mostram forte variação sazonal das comunidades em estudo, com maiores abundâncias planctónicas a ocorrer nos meses de Março (Inverno/Primavera) e menores em Novembro (Outono). Igualmente, constataram-se diferenças significativas ao nível da diversidade e abundância de plâncton dentro e entre as estações do ano estudadas. Verificou-se uma relação directa entre a profundidade da DCM e a profundidade onde se registou maior diversidade e abundância fitoplanctónica, ocorrendo esta sensivelmente aos 75 m no Verão e aos 25 m no Inverno/Primavera. A biomassa máxima de zooplâncton foi registada em Março durante a noite (57,47 mg.m-3) e a mínima em Junho durante a noite (2,98 mg.m-3). Foi igualmente em Março, o mês com maiores valores de abundância e onde se registou a menor diversidade taxonómica de zooplâncton, com um total de 95% de copépodes. Este estudo forneceu pela primeira vez informação acerca das comunidades planctónicas no banco submarino Condor, assim como demonstrou que a realização de estudos multidisciplinares e contínuos são de elevada importância para se poder realizar uma boa avaliação/interpretação da relação entre os processos biológicos e oceanográficos. ABSTRACT: The seamount ecosystems are considered highly important due to an increased marine biodiversity, and thus, high economical interest. The study site of this work was the Condor seamount, located about 10 nautical miles southwest of the island of Faial. The main objectives of this study were to characterize the planktonic communities qualitatively and quantitatively and determine their variation in time and space, as well as associate their respective distribution patterns to physical and environmental factors. For this purpose under the framework of CONDOR project (PT0040 co-financed by the EEA Grants Financial Mechanism - Iceland, Liechtenstein and Norway) seven oceanographic cruises were carried aboard R/V "Archipelago" between March 2009 and March 2010. A total of 103 water samples for phytoplankton analysis and 110 samples to determine chlorophyll a concentration were collected. CTD casts and a total of 59 samples of zooplankton were also obtained. In laboratory samples were processed, phyto and zooplankton were taxonomically identified, as well as their abundance and zooplankton biomass. The present work concerns only seven stations of biological sampling and physical/chemistry characterization of water (versus a total of about 20 sampling stations achieved in each of the cruises). The results obtained by CTD profiles revealed a stratified water column in summer and very mixed water in the Winter/Spring, as well as an oxygen maximum in July and not in March as expected. The results obtained in this work show strong seasonal variation of the communities in study, and the highest planktonic abundance occurred in March (Winter/Spring) and the lowest in November (autumn). The existence of significant differences of its diversity and abundance within and between the stations of the year studied were also indicated. A direct relationship between the depth of DCM and the depth where there was greater phytoplanktonic diversity and abundance was found occurring at 75 m in the summer and 25 m in Winter/Spring. The maximum zooplankton biomass was registered in March during the night (57,47 mg.m-3), while the minimum was in June during the day (2,98 mg.m-3). The lowest zooplankton taxonomical diversity was also registered in March, the month with highest values of abundance, with a total of 95% Copepoda. This study provided for the first time information about planktonic communities in Condor seamount and, in addition, has shown that multidisciplinary and continuous studies are of high importance to a good evaluation/interpretation of the relationship between the biological and oceanographical processes.