Marta Díaz‐Valdés

Instituto Español de Oceanografía

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Alfonso A. Ramos‐Esplá

University of Alicante

José Luis Sánchez‐Lizaso

University of Alicante

Manuel Martínez‐García

University of Alicante

A. Aldaz

University of Alicante

Yolanda Fernández‐Torquemada

University of Alicante

Gerhard Wanner

Urologische Klinik München

Beatriz Luna

University of Alicante

Joan Moranta

Instituto Español de Oceanografía

Andrés Izquierdo‐Muñoz

University of Alicante

Sergi Joher

Instituto Español de Oceanografía

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University of Alicante

Max Planck Institute for Marine Microbiology

Instituto Español de Oceanografía

Max Planck Society

Consejo Superior de Investigaciones Científicas

University of Girona

Universitat de Barcelona

Georgia Institute of Technology

Weatherford College

Ecosystem (Spain)

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Microbial community associated with the colonial ascidian Cystodytes dellechiajei

Environmental Microbiology (2006)

Manuel Martínez‐García Marta Díaz‐Valdés Gerhard Wanner Alfonso A. Ramos‐Esplá A. Aldaz

Summary The ascidian Cystodytes dellechiajei (Della Valle, 1877) (phylum Chordata, class Ascidiacea, family Polycitoridae) is a colonial tunicate that inhabits benthic rock environments in the Atlantic, Pacific and Indian Oceans, as well as the Mediterranean Sea. Its life cycle has two phases, the adult sessile colony and the free‐living larva. Both adult zooids and larvae are surrounded by a protective tunic that contains several eukaryotic cell lines, is composed mainly of acidic mucopolysacharides associated with collagen and elastin‐like proteins, and is covered by a thin cuticle. The microbiota associated with the tunic tissues of adult colonies and larva of C. dellechiajei has been examined by optical, confocal and electron microscopy and by fluorescence in situ hybridization (FISH), denaturing gradient gel electrophoresis (DGGE), and 16S rRNA gene clone library analysis. Microscopy analyses indicated the presence inside the tunic, both for the adult and the larva, of a dense community of Bacteria while only the external surface of colony cuticle was colonized by diatoms, rodophyte algae and prokaryotic‐like epiphytes. Transmission electron microscopy showed tunic eukaryotic cells that were engulfing and lysing bacteria. 16S rRNA gene analyses (DGGE and clone libraries) and FISH indicated that the community inside the tunic tissues of the adults and larvae was dominated by Alphaproteobacteria . Bacteria belonging to the phyla Gammaproteobacteria and Bacteroidetes were also detected in the adults. Many of the 16S rRNA gene sequences in the tunic tissues were related to known aerobic anoxygenic phototrophs (AAP), like Roseobacter sp. and Erythrobacter sp. In order to check whether the gene pufM , coding for the M subunit of the reaction centre complex of aerobic anoxygenic photosynthesis, was being expressed inside the ascidian tissues, two libraries, one for an adult colony and one for larva, of cDNA from the expressed pufM gene were also constructed. The sequences most frequently (64% for colony and 67% for larva) retrieved from these libraries presented > 90% aa identity with the pufM gene product of the Roseobacter ‐like group, a cluster of AAP widely detected in marine planktonic environments.

Alphaproteobacteria

Tunicate

Anoxygenic photosynthesis

Roseobacter

Zooid

Planctomycetes

10.1111/j.1462-2920.2006.01170.x

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Citations (57)

Analysis of morphological characteristics of rhodoliths as indicator of habitat complexity and fishing effects

Carmen Barberá N. Comalada Sergi Joher M. Valls-Mir Marta Díaz‐Valdés

Rhodoliths are unattached coralline red algae that roll on the seafloor and adopt spherical and/or branching morphologies. At high densities, these free-living algae form rhodolith or maerl beds, which constitute communities of high diversity in Mediterranean Sea which can be severally damaged by fishing activities. In the present study, we analyzed the morphological characteristics of rhodoliths as potential indicators of habitat complexity and fishing disturbance caused by bottom trawling. The study was carrying out in Menorca Channel, where maerl beds cover more than 50% of continental platform between 50100 m depth. Changes in rhodoliths morphology and size structure were tested analyzing the relationships with habitat complexity, comparing habitats with different structure (sand, maerl beds and soft algae beds) and comparing locations with different level of fishing pressure. Epibenthonic algae were sampled using a beam trawl of 2m width. A subsample of approximately 100 randomly chosen rhodoliths was photographed, identified and classified in different morphotypes. Measures of these rhodoliths (length of axes, diameter, perimeter, area, aspect and roundness) were obtained applying image analysis. Fishing pressure in maerl beds was defined from satellite-based Vessel Monitoring System data, defined as percentage of trawled area per year in the selected locations. Morphotypes composition was notably different between habitats but was not significantly different between the different levels of trawling intensity in maerl beds. Size and morphological parameters were different between habitats and locations with different trawling effort, but only for the most abundant species, Spongites fruticulosus and Lithotamnium coralloides. Diverse factors may affect the growth rate and morphology of the maerl species: light, nutrients, temperature, hydrodynamic, and species composition. The results of the present study showed that changes in size and morphology of deep-water rhodoliths in this area are better explained by the current velocity, depth and rhodoliths coverage more than the trawling intensity. However, the results also suggest that the reduction of the complexity of size and morphologic structure could be related with the incipient effects of fishing intensity in an area where the fishing impact were not detected by changes in algal biomass and mega-faunal species composition.

Coralline algae

Bottom trawling

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Diversity ofpufMgenes, involved in aerobic anoxygenic photosynthesis, in the bacterial communities associated with colonial ascidians

FEMS Microbiology Ecology (2009)

Manuel Martínez‐García Marta Díaz‐Valdés A. Aldaz

Ascidians are invertebrate filter feeders widely distributed in benthic marine environments. A total of 14 different ascidian species were collected from the Western Mediterranean and their bacterial communities were analyzed by denaturing gradient gel electrophoresis (DGGE) of 16S rRNA gene. Results showed that ascidian tissues harbored Bacteria belonging to Gamma- and Alphaproteobacteria classes, some of them phylogenetically related to known aerobic anoxygenic phototrophs (AAPs), such as Roseobacter sp. In addition, hierarchical cluster analysis of DGGE patterns showed a large variability in the bacterial diversity among the different ascidians analyzed, which indicates that they would harbor different bacterial communities. Furthermore, pufM genes, involved in aerobic anoxygenic photosynthesis in marine and freshwater systems, were widely detected within the ascidians analyzed, because nine out of 14 species had pufM genes inside their tissues. The pufM gene was only detected in those specimens that inhabited shallow waters (<77 m of depth). Most pufM gene sequences were very closely related to that of uncultured marine bacteria. Thus, our results suggest that the association of ascidians with bacteria related to AAPs could be a general phenomenon and that ascidian-associated microbiota could use the light that penetrates through the tunic tissue as an energy source.

Anoxygenic photosynthesis

Roseobacter

Alphaproteobacteria

Phylotype

Marine invertebrates

Planctomycetes

Microbial mat

10.1111/j.1574-6941.2009.00816.x

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Citations (14)

Dispersion of brine discharge from seawater reverse osmosis desalination plants

Desalination and Water Treatment (2009)

Yolanda Fernández‐Torquemada José Miguel González Correa Angel Loya Luis Miguel Ferrero Marta Díaz‐Valdés

Desalination of seawater has been considered as a potential solution for the water shortage problem in coastal areas and the number of projected and constructed desalination plants has significantly increased in recent years. The challenge of the desalination industry is to produce new water resources without increasing the pressure on the marine environment. Environmental impact of SWRO desalination plants is mainly associated with the discharge into the sea of the brine produced. To estimate the area of influence of the brine several models have been proposed, but validation with real data is needed. The objective of this paper is to present the results of the monitoring of the brine effluent emanating from several SWRO desalination plants in the western Mediterranean Sea in order to estimate the area of influence of the hypersaline plume. We also illustrate how the behavior of these brine discharges can differ significantly according to discharge characteristics. This information may be useful to predict effluent distribution in order to minimize the harmful effects of brine discharges into the sea.

Brine

Reverse osmosis plant

Osmotic power

10.5004/dwt.2009.576

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Spatial and Temporal Variability of Posidonia oceanica Monitoring Indicators, Valencian Community, Spain

Water (2020)

Yolanda Fernández‐Torquemada Marta Díaz‐Valdés Andrés Izquierdo‐Muñoz José Luis Sánchez‐Lizaso Alfonso A. Ramos‐Esplá

This article presents the results from the long-term Water Framework Directive monitoring of Posidonia oceanica in the Valencian Community, Spain. A total of six areas where Posidonia occurs were studied. Locations were characterized by a different ecological condition: degraded Posidonia meadows; meadows in good conditions; meadows close to the best reference conditions. The spatiotemporal variability of different indicators were sampled from 2005 to 2017. Lower quality meadows are characterized by a lower density and coverage of Posidonia, a higher proportion of dead Posidonia, a higher proportion of plagiotropic rhizomes, smaller shoots, and higher epiphyte biomass, as well as the presence of foliar necrosis marks. For all study sites, the temporal trends indicated a decrease in the quality of the meadows from 2005 to 2011 and a recovery from 2012 to 2017. Some variability observed in the indicators such as P. oceanica cover in patchy meadows, could not be explained by changes in the meadow health.

Posidonia oceanica

Potamogetonaceae

Epiphyte

10.3390/w12113235

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Ammonia‐oxidizing Crenarchaeota and nitrification inside the tissue of a colonial ascidian

Environmental Microbiology (2008)

Manuel Martínez‐García Peter Stief Marta Díaz‐Valdés Gerhard Wanner Alfonso A. Ramos‐Esplá

Summary Marine Crenarchaeota represent an abundant component of the oceanic microbiota that play an important role in the global nitrogen cycle. Here we report the association of the colonial ascidian Cystodytes dellechiajei with putative ammonia‐oxidizing Crenarchaeota that could actively be involved in nitrification inside the animal tissue. As shown by 16S rRNA gene analysis, the ascidian‐associated Crenarchaeota were phylogenetically related to Nitrosopumilus maritimus , the first marine archaeon isolated in pure culture that grows chemolithoautotrophically oxidizing ammonia to nitrite aerobically. Catalysed reporter deposition (CARD)‐FISH revealed that the Crenarchaeota were specifically located inside the tunic tissue of the colony, where moreover the expression of amoA gene was detected. The amoA gene encodes the alpha‐subunit of ammonia monooxygenase, which is involved in the first step of nitrification, the oxidation of ammonia to nitrite. Sequencing of amoA gene showed that they were phylogenetically related to amoA genes of N. maritimus and other putative ammonia‐oxidizing marine Crenarchaeota. In order to track the suspected nitrification activity inside the ascidian colony under in vivo conditions, microsensor profiles were measured through the tunic tissue. Net NO x production was detected in the tunic layer 1200–1800 μm with rates of 58–90 nmol cm −3 h −1 . Oxygen and pH microsensor profiles showed that the layer of net NO x production coincided with O 2 concentrations of 103–116 μM and pH value of 5.2. Together, molecular and microsensor data indicate that Crenarchaeota could oxidize ammonia to nitrite aerobically, and thus be involved in nitrification inside the ascidian tissue.

Crenarchaeota

Ammonia monooxygenase

10.1111/j.1462-2920.2008.01761.x

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Citations (41)

Descriptors from Posidonia oceanica (L.) Delile meadows in coastal waters of Valencia, Spain, in the context of the EU Water Framework Directive

ICES Journal of Marine Science (2008)

Yolanda Fernández‐Torquemada Marta Díaz‐Valdés Francisco J. Colilla Beatriz Luna José Luis Sánchez‐Lizaso

Abstract Fernández-Torquemada, Y., Díaz-Valdés, M., Colilla, F., Luna, B., Sánchez-Lizaso, J. L., and Ramos-Esplá, A. A. 2008. Descriptors from Posidonia oceanica (L.) Delile meadows in coastal waters of Valencia, Spain, in the context of the EU Water Framework Directive. – ICES Journal of Marine Science, 65: 1492–1497. Evaluations are provided of 21 descriptors of Posidonia oceanica meadows along the coast of Valencia, Spain, with a view to using these in implementing the European Water Framework Directive (WFD). The descriptors selected are known to respond to a variety of anthropogenic disturbances. Data were collected at 17 locations during three consecutive years. A principal components analysis was used to classify the ecological status of each locality according to five classes as prescribed by the WFD. To identify the descriptors that contributed most to similarity among localities within each class and to dissimilarity between adjacent classes, a similarity percentage analysis was performed. We also correlated the descriptors with an independent set of indicators for various types of anthropogenic pressures on the water bodies associated with the different localities. The descriptors providing the most consistent information on status as well as demonstrating a significant relationship with estimated pressures were: shoot density, shoot foliar surface, dead-matte cover, meadow cover, herbivore pressure, rhizome baring/burial, foliar necrosis, percentage of plagiotropic rhizomes, and leaf-epiphyte biomass.

Posidonia oceanica

Water Framework Directive

Georeference

Epiphyte

Potamogetonaceae

10.1093/icesjms/fsn146

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Citations (46)