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11 pages, 6 figures, 3 tables.-- Under a Creative Commons license, Zostera marina and Z. noltii are two dominant meadow-forming seagrass species in temperate regions in the northern hemisphere. Seagrass meadows provide several goods and ecological services and rank amongst the most valuable ecosystems worldwide. Phenological shifts in Zostera species occur along latitudinal or temperature gradients, leading to an expectation for distinct seasonal dynamics and annual production in Spain and Ireland. Despite their global ecological importance, seasonal seagrass traits of populations exposed to contrasting climate settings from Ireland and southern Spain are poorly described. To address this gap, we evaluated the seasonal vegetative development (morphology, population structure, and productivity) of Z. marina and Z. noltii populations exposed to cold (western Ireland) and warm (southern Spain) temperatures over a year-long period. Our results highlight contrasting dynamics of Z. marina populations across their temperature range. The Irish population exhibited maximal growth during warmer months while the Spanish population revealed signs of growth reduction under maximum annual temperatures. Our results suggest that plants of Z. marina in Ireland were temperature-limited at most times, but in southern Spain exceeded their optima temperature for growth during summer. In addition, Irish and Spanish Z. noltii populations displayed differential vegetative dynamics and population structures, likely related to the contrasting local temperature regimes. These differences were particularly evident in summer when shoot size and growth rates were reduced in warm-temperate locations. This study represents an essential comparative baseline for future assessments of ecological status, and anticipated growth stress induced by climate change across the distributional gradient, of these important Zostera species, This project was supported by a College of Science of the National University of Ireland (NUI Galway) PhD Scholarship to Pedro Beca-Carretero, With the institutional support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S)

Eutrophication causes tremendous losses to seagrass around the globe. The effects of nutrient loading vary along environmental gradients, and wave forces especially are expected to affect meadow stability, nutrient status, and responses to nutrient supply. Here, we surveyed the pristine subtropical intertidal seagrass system of Banc d’Arguin, Mauritania, to characterise Zostera noltii in terms of morphology (biomass allocation, leaf length and area, rhizome internode length), nutrient content (carbon: C, nitrogen: N, phosphorus: P, iron: Fe, aluminium: Al), and patterns in δ13C and δ15N across a wide gradient of hydrodynamic conditions. We subsequently assessed temporal variability in seagrass stability and nutrient fluxes, as well as responses to experimental fertilisation (pulses of + N, + P, + N + P) on three meadows representing different degrees of wave-force (exposed, intermediate and sheltered). The large-scale survey revealed a marked increase in N and P limitation with increasing wave energy. The overall low leaf %N (1.74 ± 0.04; mean ± se) and N:P ratio (8.67 ± 0.14) suggests that the area is N-limited. Seasonal variation in seagrass cover and biomass showed the exposed site to be the most stable and the sheltered site the least. Variation in δ15N signatures indicates seasonal shifts in N sources at the exposed site only. Fertilisation with + N and + N + P induced seagrass mortality at the exposed site, while at the sheltered site it was + P that degraded seagrass. Collectively, our results indicate that with increasing wave forces, the degree of stability of seagrass beds increases, but nutrient limitation and vulnerability to eutrophication increase as well.

Seagrasses are highly productive ecosystems and hotspots for biodiversity, providing a plethora of benefits to the environment and to people. Their value in sequestering and storing carbon is increasingly being recognised, as the world searches for ways to mitigate the effects and slow the pace of climate change. However, many uncertainties remain, with basic information such as average carbon stocks, variability and species-specific differences missing for many regions. This study evaluates, for the first time, the carbon storage capacity of Zostera noltii and Zostera marina from intertidal seagrass meadows in Scotland. Sediment carbon stocks in the top 50 cm from vegetated and reference unvegetated plots were quantified at 10 estuaries distributed along the Scottish east and west coasts. The organic carbon stocks in the top 50 cm of the seagrass sediment ranged from a minimum of 14.94 Mg C ha−1 at the Moray Firth to a maximum of 105.72 Mg C ha−1 at the Firth of Forth, with a mean (±SD) of 54.79 ± 35.02 Mg C ha−1 across the 10 estuaries sampled. Moreover, seagrass areas showed enhanced carbon storage compared to reference unvegetated ones, however this was highly variable across depth, and among sites and estuaries. This paper addresses key gaps in knowledge concerning the role of intertidal Scottish seagrass meadows as carbon sinks and discusses the implication of this emerging information for their effective management and conservation.

The limiting effects of stressors like desiccation, light and salinity on seagrass growth and distribution are well-studied. However, little is known about their interactive effects, and whether such effects might differ among populations that are adapted to different local conditions. In two laboratory experiments we tested (a) if growth and development of intertidal, temperate Zostera noltii is affected by emergence time (experiment 1 and 2), and (b) how this is affected by an additional, second stressor, namely shading (experiment 1) or high salinity (25, 30 and 35, experiment 2). In addition, we tested (c) whether the effects of emergence time and salinity varied between three different European seagrass populations (Saint-Jacut/France, Oosterschelde/The Netherlands, and Sylt/Germany), which are likely adapted to different salinity levels (experiment 2). In both experiments, emergence of 8 h per tidal cycle (of 12 h) had a negative effect on seagrass relative growth rate (RGR), and aboveground biomass. Emergence furthermore reduced either rhizome length (experiment 1) or belowground biomass (experiment 2). Shading (experiment 1) resulted in lower RGR and a two-fold higher aboveground/belowground ratio. We found no interactive effects of emergence and shading stress. Salinity (experiment 2) did not affect seagrass growth or morphology of any of the three populations. The three tested populations differed greatly in morphology but showed no differential response to emergence or salinity level (experiment 2). Our results indicate that emergence time and shading show an additive negative effect (no synergistic or antagonistic effect), making the plants still vulnerable to such combination, a combination that may occur as a consequence of self-shading during emergence or resulting from algal cover. Emergence time likely determines the upper limit of Z. noltii and such shading will likely lower the upper limit. Shading resulted in higher aboveground/belowground ratios as is a general response in seagrass. Z. noltii of different populations originating from salinity 30 and 35 seem tolerant to variations in salinity within the tested range. Our results indicate that the three tested populations show morphotypic rather than ecotypic variation, at least regarding the salinity and emergence, as there were no interactive effects with origin. For restoration, this implies that the salinity regime of the donor and receptor site of Z. noltii is of no concern within the salinity range 25–35.

Four metabolisability trials on captive Wigeons were conducted comparing a complete pelleted diet with others where Taraxacum officinalis and Zostera noltii were added. The daily dry matter (DM) intake of Wigeons varied from 54.4 to 65.5 g/day and the amount of nutrients received from the four diets was similar. The nitrogen (N) content of droppings statistically diminished when Wigeons were fed diets containing Zostera noltii. Correlation among cell wall components (CWC) of droppings and that of intakes was always highly significant and positive. The DM metabolisability of the four diets was 42-51 %. The crude protein (CP) metabolisability varied significantly from 21 % for the diet with Taraxacum to 39 % for that with the Zostera collected in June. The metabolizabilities of CWC also differed significantly among diets. The apparent metabolizabilities of ash with the Zostera diets were significantly higher when compared to those of two other diets.

The inhibitory effects of crude extracts of Zostera marina L. and Zostera noltii Hornemann on the growth of the toxic red tide dinoflagellate Alexandrium catenella were investigated through bio-assays. Methanolic and aqueous extracts were prepared from fresh and detrital leaves of Z. marina and Z. noltii collected in the Thau lagoon and Arcachon bay (France). All the extracts exhibited significant inhibition of A. catenella growth, whatever the species and without the need of continuous addition of extracts. The effective concentrations (EC 50 ) varied in the range 0.036–0.199 g L −1 for Z. noltii and 0.036–0.239 g L −1 for Z. marina . Methanolic extracts prepared from fresh plant tissues were the most potent, with EC 50 of 0.036–0.039 and 0.036–0.045 g L −1 , for Z. noltii and Z. marina , respectively. After exposure to the extracts, Alexandrium cells exhibited severe morphological anomalies. Hence many cells exhibited a lytic membrane and became necrotic. Cellular degradation appeared dose- and time-dependent. The observed algicidal activities demonstrated the existence of bioactive molecules in the tissues of Zostera leaves, which were stable in the culture medium. The chemical contents of the crude extracts were determined by NMR, LC/MS, and quantitative HPLC. Results showed the predominance of flavonoids and phenolic acids. The total phenolics concentrations correlated negatively with the EC 50 values, suggesting that these secondary metabolites might be responsible for the observed algicidal effects.

International audience; The influence of phenological variations on the reflectance of the intertidal marine angiosperm Zostera noltii was studied using spectroradiometry and pigment analysis. Leaves were sampled each month from March to November and spectral reflectance was measured in the 400-900 nm wavelength range in the laboratory for increasing biomass. High Performance Liquid Chromatography (HPLC) was used to assess the pigment composition and concentration of the leaves and their epiphytes. Several vegetation indices (VIs) were tested for their sensitivity to seasonal variations, from NDVI-like ratios to indices based on derivative analysis. Pigment concentration showed a seasonal effect, with the highest concentrations observed in summer, synchronous with the above-ground biomass peak. The seasonal variations were clearly visible in the leaf reflectance spectrum, showing for the same amount of vegetation, lower reflectance in summer for the visible wavelengths and a higher near-infrared (NIR) plateau compared to the other months. Indices based on the difference between the red and NIR reflectance values, typically all the NDVI-like ratios, were the most sensitive to seasonal variations in pigment concentration. In fact, seasonal effects were systematically reduced for VIs including a blue band correction, namely the modified Specific Ratio (mSR(705)), the modified Normalized Difference (mND(705)), the modified NDVIs for Landsat, FORMOSAT and narrow band NDVI (mNDVI(673)) as well as the Atmospherically Resistant Vegetation Index (ARVI). However, these indices showed a faster saturation for increasing seagrass biomass, except for the mSR(705), which was the least sensitive to biomass saturation. The interesting properties of this index suggest that it should now be tested for airborne or satellite remote sensing mapping of Z. noltii beds but it requires a high spectral resolution and cannot be applied to multispectral satellite images.

We experimentally simulated the temporality of the interactions between intertidal seagrasses and phytoplankton in the context of nutrient enrichment from continental origin. Phytoplankton development was retarded after 1-day exposure to intertidal Zostera noltii Hornemann vegetation samples, with respect to control treatments. This was not explained by resource competition and we hypothesized a direct interference between seagrass leaves and phytoplankton. After separation from the vegetation in 5-day incubations, the final yield of large phytoplankton, mainly diatoms and haptophytes, was determined by nutrient loading. In contrast, Synechococcus-like cells (SYN), phototrophic picoeukaryotes and nanophytoplankton decreased after day 3, most likely due to grazing control. A second experiment was designed to test the pelagos-benthos coupling in more detail. Therefore, we compared the effect of aboveground biomass of Z. noltii alone with the effect of the entire vegetation including the sediment. This experiment did not provide unequivocal support for our initial hypothesis on direct interference competition between Z. noltii leaves and phytoplankton. Surprisingly, we found a spectacular decrease of SYN, phototrophic picoeukaryotes and nanophytoplankton in treatments with Z. noltii vegetation including the sediment, which could be attributed to benthic grazing by suspension feeders.

Background and Aims The dwarf eelgrass, Zostera noltii, is a predominant inhabitant of soft-bottom intertidal regions along the coasts of northern Europe. It is a monoecious, protogynous angiosperm in which the potential for self-fertilization and inbreeding are high, especially if clone sizes exceed pollen dispersal distances. The aim of the present study was to determine the relationship between mating system and clonal structure, examine the relative roles of geitonogamous selfing and biparental inbreeding, measure pollen availability (multiple paternities) and estimate pollen dispersal.Methods A 100-m(2) plot was established in a large, intertidal Z. noltii meadow on the island of Sylt in the German Wadden Sea. A total of 256 adult shoots was sampled: one from the centre of 100 fixed 1-m(2) quadrats (large scale resolution) and an additional 156 from within eight randomly selected 1-m(2) sub-quadrats (small-scale resolution). DNA was extracted from seeds and leaf tissue of all samples and genotyped with nine microsatellite loci.Key Results Mating system analysis revealed high multilocus and single locus outcrossing rates. Average pollen dispersal distance was nearly the same as the average genet (clone) size. Multiple paternity was common and 20-30% of mature seeds originated from matings within the plot. Among inbred seeds, most resulted from geitonogamy rather than biparental inbreeding.Conclusions Moderate disturbances intrinsic to the intertidal habitat appear to facilitate seed recruitment by gap formation. Pollen dispersal distances are sufficient to maintain outcrossing and high clonal diversity.

The spatial variability of seagrass meadows in Arcachon Bay, was studied between 1988 and 2008 using a combination of mapping techniques based on aerial photographs for intertidal dwarf-grass (Zostera noltti) beds and acoustic sonar for permanently submerged eelgrass (Zostera marina) populations. The results show a severe decline over the period for both species, as well as an acceleration of the decline since 2005 for Z. noltii. The total surface regression over the studied period is estimated to be 22.8 km(2) for Z. noltii and 2.7 km(2) for Z. marina, which represent declines of 33 and 74% respectively. Environmental data time series spanning the same period were investigated in order to seek the causes for such a decline. The calculated inter-annual trends for temperature, salinity, nitrate plus nitrite, ammonia, suspended sediment and chlorophyll a did not identify any clear environmental change capable of explaining the observed seagrass regression. For instance, no evident sign of eutrophication was observed over the study period. On the other hand, we suggest that the observed variations of ammonia in the inner part of the lagoon are a symptom of the seagrasses' disappearance and thus, a first sign indicating a change of the Arcachon Bay ecosystem towards more instability and vulnerability. Several hypotheses to explain the observed seagrass decay are proposed. (C) 2010 Elsevier Ltd. All rights reserved.

In estuaries, eelgrass meadows contribute to fundamental ecosystem functions of estuaries, providing food to several predators and buffering the negative effects of eutrophication. We asked whether the presence of the eelgrass Zostera noltii decreased the nitrogen concentration in the overlying water, affected the sources of nitrogen sequestrated by primary producers and changed the benthic and pelagic food web structures. We also studied the importance of these food webs in providing food to fish. We compared bare sediment to sediment covered by a Z. noltii meadow, and examined nutrient concentrations in the water column and δ15N in primary producers as indicators of anthropogenic inputs of nutrients. We then measured both δ13C and δ15N in the tissues of plants and consumers to establish food web structures. There were no differences in the concentrations and sources of nitrogen between sites. Rather, δ15N values indicated anthropogenic inputs of N (e.g. sewage discharges, agriculture) in both sites. There were no major differences in the structure of the planktonic food web, which was in part sustained by particulate organic matter and supported most predator fish, and in the structure of the benthic food web. Nonetheless, there were differences in the sources of food for omnivore consumers and for the detritivore Scrobicularia plana. Overall, the benthic food web did not use food derived from the eelgrass or macroalgae deposited on the substratum. Suspension feeders used particulate and sediment organic matter, whereas the δ13C and δ15N values of the other consumers indicated a likely contribution of benthic microalgae. Furthermore, in both habitats we found large variability in the isotope signatures of benthic macrofauna consumers, which did not allow distinguishing clearly different trophic groups and indicated a high level of omnivory and a mixed diet opportunistically making use of the availability of food in the surroundings.

The Mondego estuary is a well-described system located on the North Atlantic Ocean, where cultural eutrophication progressed over the last decades of the 20th century. Consequently, and due to a large productivity of Ulva spp., Zostera noltii meadows were severely reduced with a concomitant decrease in environmental quality. In 1998, experimental mitigation measures were implemented, via changes in hydrology to increase circulation and diversion of nutrient-rich freshwater inflow, to reverse the process in the most affected area of the estuary – its South arm. The objective of this study was to assess the differences in response of primary producer assemblages to the implemented measures to reduce eutrophication. Results show that the mean concentrations of DIN suffered a notorious decrease due to a significant reduction in the ammonium concentration in the water column, while DIP increased significantly. Primary producer assemblages showed different responses to these changes: phytoplankton, measured as concentration of chlorophyll a , did not show any significant changes; green macroalgae, mostly Ulva spp., suffered a large reduction in biomass, whereas Gracilaria gracilis and the macrophyte Zostera noltii biomasses increased greatly. Results show that phytoplankton biomass has remained constant and suggest that the reduction in ammonium could have been responsible for the changes in the green macroalgal biomass. Light was the most likely factor in the response of seagrass whereas red macroalgal reaction seemed to be dependent on both light and ammonium.

Marine and coastal environments are among the most ecologically and socio-economically important habitats on Earth. However, climate change associated with a variety of anthropogenic stressors (e.g. eutrophication) may interact to produce combined impacts on biodiversity and ecosystem functioning, which in turn will have profound implications for marine ecosystems and the economic and social systems that depend upon them. Marine and coastal environments are among the most ecologically and socio-economically important habitats on Earth. However, climate change associated with a variety of anthropogenic stressors (e.g. eutrophication) may interact to produce combined impacts on biodiversity and ecosystem functioning, which in turn will have profound implications for marine ecosystems and the economic and social systems that depend upon them. Over period 1980–2000, the environment of the Mondego estuary, Portugal, has deteriorated through eutrophication, manifested in the replacement of seagrasses by opportunistic macroalgae, degradation of water quality and increased turbidity, and the system has also experienced extreme flood events. A restoration plan was implemented in 1998 which aimed to reverse the eutrophication effects, especially to restore the original natural seagrass (Zostera noltii) community. This paper explores the interactions between extreme weather events (e.g. intense floods) and anthropogenic stressors (e.g. eutrophication) on the dynamics of the macrobenthic assemblages and the socio-economic implications that follow. We found that during the previous decade, the intensification of extreme flooding events had significant effects on the structure and functioning of macrobenthic communities, specifically a decline in total biomass, a decline in species richness and a decline in suspension feeders. However, the earlier eutrophication process also strongly modified the macrobenthic community, seen as a decline in species richness, increase in detritivores and a decline in herbivores together with a significant increase in small deposit-feeding polychaetes. After the implementation of the management plan, macrobenthic assemblages seemed to be recovering from eutrophication, but it is argued here that those earlier impacts reduced system stability and the resilience of the macrobenthic assemblages, so that its ability to cope with other stressors was compromised. Thus, heavy flooding in the Mondego region during the recovery process had more severe effects on these assemblages than expected, effectively re-setting the recovery clock, with significant socio-economic impacts (e.g. high mortality of fish in fish farms, and a large decline of economically important species, such as the bivalves Scrobicularia plana and Cerastoderma edule). The frequency and magnitude of these extreme events is predicted to increase in future years [IPCC WGI, 2001. Climate change 2001: the scientific basis, contribution of working group I to the third assessment report of the Intergovernmental Panel on Climate Change (IPCC). In: Houghton, J.T., Ding, Y., Griggs, D.J., Noguer, M., van der Linden, P.J., Xiaosu, D. (Eds.), Cambridge University Press, UK, 944 p.] and there is a risk that impacted ecosystems will never recover fully, with far-reaching consequences for human well being

The relation between net dimethyl sulfide (DMS) production and changes in near surface (0-5 mm) oxygen concentrations in a sea grass (Zostera noltii Hornem)-covered intertidal sediment ecosystem was examined during a diel cycle. Sediment covered with Zostera was found to be more oxygenated than uncovered sediment during the period of photosynthesis. This phenomenon was probably caused by radial oxygen loss of the Zostera root-rhizome system. The population sizes of the three functional groups of microbes mainly responsible for the concentration of DMS, the dimethylsulfoniopropionate (DMSP)-demethylating, DMSP-cleaving and DMS-oxidizing bacteria. were quantified by most probable number (MPN) methodologies. Sediments with Zostera supported substantially higher populations of both aerobic (149 x 10(6) cm(-3) DMSP-utilizing and 0.4 x 10(6) cm(-3) DMS-oxidizing) and anaerobic (43 x 10(6) cm(-3) DMSP-utilizing and 0.4 x 10(6) cm(-3) DMS-oxidizing) microorganisms than sediments without Zostera (DMSP-utilizing aerobes and anaerobes both 2 x 10(6) cm(-3) and DMS-oxidizing aerobes and anaerobes both 0.2 x 10(6) cm(-3)). Experiments conducted with sediment cores and sediment slurries suggested that the net production of DMS ill these sediments was significantly lower during oxic periods than during anoxic periods. Intact sediment cores with and without Zostera produced DMS when incubated under anoxic/dark conditions (97.0 and 53.6 nmol DMS m(-2) h(-1). respectively), while oxic/light-incubated cores did not produce detectable amounts of DMS. In addition, kinetic parameter values (V-max and K-m) fur DMSP degradation in cell suspensions of isolated DMSP-demethylating and DMSP-cleaving bacteria were measured and compared to documented values for other strains. Both V-max and K-m values for DMSP-demethylating organisms were Found to be relatively low (14.4-20.1 nmol DMSP mg protein(-1) min(-1) and 4.1-15.5 mu M, respectively) while these parameter values varied widely in the group of the DMSP cleaving organisms (6.7-1000 nmol DMSP mg protein(-1) min(-1) and 2-2000 mu M respectively). It was hypothesized that a diel rhythm in DMS emission occurred, with a relatively low net production during the day and a high net production during the night. Environmental changes which result in increased anoxic conditions in coastal sediments, such as an increase in eutrophication, may therefore result in increased atmospheric DMS emission rates. (C) 2000 Federation of European Microbiological Societies. Published by Elsevier Science B.V. Ail rights reserved.

Seagrasses are present in the entire coastal habitats around the world. These coastal habitats provide many goods and services which maintain the integrity of coastal ecosystems and consequently the quality of human life of the communities involved. In recent years, interest in these environments has resulted in its incorporation into European legislation to protect the natural heritage. However, seagrasses show a global reduction as a result of the development process and pollution, eutrophication and habitat degradation. The Ecological Niche Factor Analysis (ENFA) was used to predict habitat suitability of Zostera noltii, a dominant species of intertidal meadows of Galicia. Within the ecological variables used in analysis Phi and redox potential mainly explain the presence of Zostera noltii in the study area with an adjustment of 90%. The predictive ability of ENFA analysis is presented as a useful tool for environmental public managers to manage the coastal spaces and for those who must design strategies for future adaptation.

Rates of nitrogen fixation (measured as acetylene reduction) in the rhizosphere of the seagrass Zostera noltii were highly dependent upon plant photosynthetic activity being significantly stimulated at elevated CO2 concentrations and by light, both in the short-term and over diurnal cycles. Stimulation by light became insignificant when 5 mM sucrose was added to the sediment porewater, indicating that in the absence of added carbon sources, light stimulation was due to direct inputs of plant photosynthate to the rhizosphere. Addition of a range of carbon sources to the rhizosphere sediment stimulated rates of acetylene reduction, with this stimulation being significant for sucrose and lactate. Surprisingly, whilst low additions of ammonium to the sediment porewater (10 to 50 mu M) inhibited 50% of acetylene reduction activity, approximately 30% of this activity persisted in the presence of 1 mM ammonium chloride; this indicating that in at least a proportion of the N-fixing community, nitrogenase activity was not regulated in the short term by the availability of alternative nitrogen sources.

Background The relationship between species diversity and components of ecosystem stability has been extensively studied, whilst the influence of the genetic component of biodiversity remains poorly understood. Here we manipulated both genotypic and allelic richness of the seagrass Zostera noltii, in order to explore their respective influences on the resistance of the experimental population to stress. Thus far intra-specific diversity was seldom taken into account in management plans, and restoration actions showed very low success. Information is therefore needed to understand the factors affecting resistance and resilience of populations. Results Our results show a positive influence of both allelic and genotypic richness on the resistance of meadows to environmental perturbations. They also show that at the low genotypic (i.e. clonal) richness levels used in prior experimental approaches, the effects of genotypic and allelic richness could not be disentangled and allelic richness was a likely hidden treatment explaining at least part of the effects hitherto attributed to genotypic richness. Conclusions Altogether, these results emphasize the need to acknowledge and take into account the interdependency of both genotypic and allelic richness in experimental designs attempting to estimate their importance alone or in combination. A positive influence of allelic richness on resistance to perturbations, and of allelic richness combined with genotypic richness on the recovery (resilience) of the experimental populations is supported by differential mortality. These results, on the key species structuring of one of the most threatened coastal ecosystem worldwide, seagrass meadows, support the need to better take into account the distinct compartments of clonal and genetic diversity in management strategies, and in possible restoration plans in the future., This work was funded by the project DIVSTAB (POCI/MAR/60179/2004) of the Portuguese Science Foundation and FEDER, and by the project Clonix (ANR-11-BSV7-007) of the French National Research Agency. Sónia Massa was funded by the fellowship SFRH/BD/46785/2008 of the Portuguese Science Foundation.

Las praderas de angiospermas marinas son uno de los ecosistemas litorales más importantes del planeta, tanto por las funciones que desempeñan en el ecosistema, como por los servicios ecológicos que repercuten en la población humana. Por su ubicación en la zona litoral las angiospermas marinas están sometidas a los impactos generados por diversas actividades antrópicas (por ejemplo, construcciones en el litoral o vertidos de contaminantes). La preocupación por la conservación de los espacios naturales se ha convertido en el objetivo principal de varias Directivas Europeas, y en particular de la Directiva Marco de Agua. Esta Directiva tiene como objetivo alcanzar en 2015 una buena calidad de todas las masas de aguas superficiales y subterráneas. Dentro de la aplicación de esta Directiva, las angiospermas marinas se han definido como un sub-elemento biológico para la evaluación de la calidad de las masas de agua costeras y de transición. Este hecho ha propiciado el desarrollo de diversas herramientas basadas en las especies europeas de angiospermas marinas (Zostera noltii, Zostera marina, Cymodocea nodosa y Posidonia oceanica) que permiten determinar la calidad ecológica del agua en la que habitan. El objetivo de esta tesis es continuar con el desarrollo de dichas herramientas y aplicarlas al sur de la Península Ibérica, donde hasta la fecha no se tiene constancia de su uso. En primer lugar, se ha desarrollado un nuevo índice multimétrico para evaluar la calidad ecológica. Dicho índice (ZoNi) está basado en la especie Z. noltii y ha sido aplicado satisfactoriamente en el sur de la Península Ibérica. Constituye una aportación novedosa a la bibliografía, ya que anteriormente no se habían desarrollado ese tipo de índices ni para esta especie ni para esta zona. En segundo lugar, se ha evaluado la respuesta de dicho índice a lo largo de un gradiente de contaminación, lo cual subraya la utilidad del índice en el campo de la gestión ambiental y en el control de los efectos de determinadas actividades antrópicas. En tercer lugar, se ha propuesto la aplicación de un índice multimétrico para la especie C. nodosa y se ha descrito la influencia de la biogeografía. El índice utilizado (CYMOX) fue previamente descrito para el Delta del Ebro, y fue necesario adaptarlo para su aplicación en el sur de la Península Ibérica, ya que se trata de una zona de transición entre el Atlántico y el Mediterráneo. En cuarto lugar, se comprobó la variación estacional de los índices en praderas de Z. noltii, y C. nodosa de la bahía de Cádiz, concluyéndose que el verano es la época óptima para la aplicación de estos índices. En quinto lugar, se implementó en el sur de la Península Ibérica uno de los primeros índices multimétricos desarrollados para P. oceanica (POMI). Finalmente, con los resultados obtenidos de la aplicación de los índices y el análisis de las presiones antrópicas que afectan a las praderas, se realizó un estudio integrado para determinar el estado ecológico de las masas de agua del sur de la Península Ibérica mediante un nuevo índice combinación de los anteriores (índice SISIP), a la vez que se describieron las implicaciones para la gestión de zonas costeras derivadas del uso de estas herramientas., Seagrass meadows form one of the most important coastal ecosystems worldwide, not only by their ecosystem functions, but for the ecological services they provide to the human population. As seagrasses are located in the littoral zone, they are subjected to several anthropogenic pressures (e.g. coastal engineering, pollution effluents). The awareness for the conservation of natural areas became the main objective for several European Directives, and particularly for the Water Framework Directive. This Directive aims to achieve in 2015 a good quality status for all the water bodies (i.e. surface and ground waters). According to the application of this Directive, seagrasses have been defined as a biological sub-element for the quality assessment of coastal and transitional water bodies. This has been reflected in the development of several tools using the European seagrass species (i.e. Zostera noltii, Zostera marina, Cymodocea nodosa and Posidonia oceanica) for the quality assessment of the water bodies where they thrive. The aim of this work was to continue with the development of these environmental tools and their successful application to the south Iberian Peninsula, where they have not yet been implemented. First, a new multimetric index for the assessment of the ecological status based on the species Z. noltii (ZoNi) was developed and applied in the south Iberian Peninsula. This constitutes an innovative contribution as there are no previous references of an index development for such species in that area. Secondly, the response of ZoNi to an environmental pollution gradient was evaluated, highlighting the role of the index for the environmental management and monitoring of anthropogenic activities. Third, an index for C. nodosa was applied and the biogeographical influence was described. This index (CYMOX) was originally described for the Ebro Delta, and was adapted for its application in the south Iberian Peninsula, as this area constitutes a transitional zone between the Atlantic and the Mediterranean. In the fourth place, seasonal fluctuations of the indices based on Z. noltii and C. nodosa were described for Cadiz Bay, concluding that summer is the optimal season for the index applicability. In the fifth place, one of the first multimetric indices developed for P. oceanica (POMI) was implemented in the south Iberian Peninsula. Finally, the results obtained with these seagrass indices, and the assessment of anthropogenic pressures around the meadows was integrated into a new combined index (SISIP) to determine the ecological status assessment of South Iberian Peninsula water bodies. In addition, the implications for coastal management derived from the use of these tools were addressed., 142 páginas

An in-depth knowledge of solutes advection and turbulent diffusion is crucial to estimate dispersion area and retention time (t R) of pollutants within seagrass habitats. However, there is little knowledge on the influence of seagrass habitat fragmentation on such mechanisms. A set of dye tracer experiments and acoustic Doppler velocimeter measurements (ADV) were conducted. Solute transport conditions were compared in between fragmented (FM) vs homogeneous (HM) intertidal meadows, and in vertical gradients (canopy vs overlaying flow). Results showed the highest horizontal diffusion coefficient (K y, c.a. 10 -3m 2s -1) on FM and at the canopy-water column interface, whereas t R (2.6-5.6min) was not affected by fragmentation. It suggests that (1) FM are more vulnerable to pollution events in terms of dispersion area and (2) at low tide, advection rather than turbulent diffusion determines t R. Furthermore, Taylor's theorem is revealed as a powerful tool to analyze vertical gradients on K y within seagrass canopies. © 2012 Elsevier Ltd., This work was supported by the Spanish National Research Project IMACHYDRO (CTM2008-0012/MAR) and by the Andalusian Excellence Research Project FUNDIV P07-RNM-2516. First author is supported by a FPI grant of the Spanish Ministry of Science and Technology.

Dissolved organic nitrogen (DON) acts as a large reservoir of fixed nitrogen. Whereas DON utilization is common in the microbial community, little is known about utilization by macrophytes. We investigated the ability of the coexisting temperate marine macrophytes Zostera noltii, Cymodocea nodosa, and Caulerpa prolifera to take up nitrogen and carbon from small organic substrates of different molecular complexities (urea, glycine, L-leucine, and L-phenylalanine) and from dissolved organic matter (DOM) derived from algal and bacterial cultures (substrates with a complex composition). In addition to inorganic nitrogen, nitrogen from small organic substrates could be taken up in significant amounts by all macrophytes. Substrate uptake by the aboveground tissue differed from that of the belowground tissue. No relationships between carbon and nitrogen uptake of small organics were found. The preference for individual organic substrates was related to their structural complexity and C:N ratio. Uptake of algae-derived organic nitrogen was of similar magnitude as inorganic nitrogen, and was preferred over bacteria-derived nitrogen. These results add to the growing evidence that direct or quick indirect DON utilization may be more widespread among aquatic macrophytes than traditionally thought. © Inter-Research 2011., This research was supported by the regional government of Andalusia project FUNDIV (P07- RNM-2516), the Spanish Project CTM2008-00012/MAR, a European Reintegration Grant (MERG-CT-2007-205675), a travel grant from Schure-Beijerinck-Popping Fund (SBP/ JK/2007-32) and the Netherlands Organization for Scientific Research.

Zostera noltii es una fanerógama marina de pequeño porte que habita el intermareal de gran parte de la costa Atlántica Europea. En los fangos intermareales del sur de la Peninsula Iberica, bajo condiciones estacionales habituales, estas poblaciones describen un patrón anual unimodal controlado principalmente por la disponibilidad de luz. Las variaciones aleatorias de las variables externas pueden desencadenar variaciones morfométricas a nivel de población, provocando un cambio en su estrategia de crecimiento. En esta tesis se muestra en detalle el patrón anual de variables demográficas y dinámicas y se demuestra como la plasticidad morfométrica permite a esta especie recuperarse rápidamente tras impactos físicos de rango moderado., Zostera noltii is a small size seagrass that inhabits the intertidal zone of most of the European Atlantic coast. In the South Iberican tidal flats, under usual seasonal conditions, these populations describe a unimodal annual pattern controlled mainly by the availability of light. Random variations of external variables can trigger morphometric changes at the population level, causing a change in its growth strategy. This thesis shows in detail the annual pattern of demographic and dynamic variables and demonstrate how morphometric plasticity allows this species to recover quickly after physical impacts of moderate range., Esta tesis doctoral ha sido financiada por la Unión Europea (programa INTERREG II, proyecto 12/REGII/6/96) y se ha desarrollado en el seno del grupo de investigación andaluz ESTRUCTURA Y DINAMICA DE ECOSISTEMAS ACUATICOS (RNM-214) de la Universidad de Cádiz., 229 páginas

Este estudio se llevó a cabo en las Marismas del Odiel (Huelva, SO España). En él se cuantifican la acreción y erosión de sedimentos en taludes desarrollados en canales intermareales y en las planicies intermareales subayacentes. Se registró una erosión generalizada de los taludes, la cual se vería potenciada por actuaciones antrópicas como el tráfico naval y la alteración de la hidrodinámica del estuario por la construcción de diques. Las pérdidas de marismas en la Reserva Integral de Isla de Enmedio se estimaron en 3000 m2/ año, lo que supone una movilización de 1850 m3 de sedimentos. Esta fuerte erosión podría tener una gran influencia en la conservación de este espacio natural protegido, además de acelerar la colmatación de los canales del estuario. La vegetación, entre la que destacaron las praderas de Zostera noltii, disminuyó la erosión, potenciando la acreción. La dinámica vertical de sedimentos en las planicies intermareales mostró un patrón estacional con una relación clara entre la erosión y la distribución de las lluvias. Se discuten medidas de control de la erosión y rehabilitación de las zonas afectadas. This study was carried out in Odiel Saltmarshes (Huelva, SWSpain). Erosion and accretion in slopes and intertidal mud flats were measured. Our results point out a general retrogression of slopes. Its intensity would depend on anthropic actions as boats traffic and alteration of estuary circulation by dykes construction. In the Integral Reserve of Enmedio Island, horizontal losses by erosion in slopes reached 3000 m2/year, which would imply the mobilization of 1850 m3 of sediments. This strong erosion could cause important changes in this protected area and to selt-up of the navigable channels of the estuary. Vegetation, as prairie of eelgrass Zostera noltii, decreased erosion and increased acretion rates. Sediment vertical dynamic in intertidal mud flats showed a seasonal pattern with a direct relation between erosion and rainfall distribution. Erosion control and rehabilitation in eroded areas are discussed.

The marine angiosperm Zostera noltii (dwarf eelgrass), an important facilitator species and food source for invertebrates and waterfowl, predominantly inhabits intertidal habitats along eastern Atlantic shores from Mauritania to southern Norway/Kattegat Sea and throughout the Mediterranean, Black and Azov seas. We used 9 microsatellite loci to characterize population structure at a variety of spatial scales among 33 populations from 11 localities throughout the entire biogeographic range. Isolation by distance analysis suggested a panmictic genetic neighborhood of 100 to 150 km. At the global scale, a neighbor-joining tree based on Reynolds distances revealed strongly-supported groups corresponding to northern Europe, Mauritania and the Black/Azov Sea; separate Mediterranean and Atlantic-Iberian groups were poorly supported. Clones (genets with multiple ramets) were present in most populations but were generally small (ca.

Dissertação mest., Biologia Marinha, Universidade do Algarve, 2009 Direct fish herbivory is not a well studied subject in seagrass research. This work tried to focus that problem in transplanted and natural seagrass species in the Luiz Saldanha Marine Park and Sado estuary. The species studied were Cymodocea nodosa, Zostera marina and Zostera noltii and the herbivorous fish Sarpa salpa (salema). In transplanted and natural seagrass the intensity of herbivory was assessed through the analysis of length, percentage of leaves with bite marks and biomass. These variables were analysed for plants with protections against herbivores and plants without protections. The place of the leaf with higher percentage of bite marks was also assessed. Another factor analysed was if the placement of artificial seagrass in the middle of real ones would deter herbivores from feeding on the plants. In the laboratory the food preference of the salemas was tested using the three species used in the study site. The analysis allowed to conclude that the protections against herbivores work since the percentage of leaves with bite marks was lower. However, these protections prevent the normal development of seagrass because they get clogged up with algae and keep light and water flow from getting to the plants. The area of the leaf with higher percentage of bite marks is the tip, where there are, usually, more epiphytes. Placing artificial seagrass doesn’t deter herbivores from eating the real seagrass. The analysis of length (between protected and unprotected seagrass leaves) varies from experiment to experiment, in some they’re the same and others it’s clearly different. But it’s evident the difference between the initial and final length of the leaves. It wasn’t possible to determine which species salemas preferred. Herbivory plays a negative role in the establishment of transplanted seagrass meadows in Luiz Saldanha Marine Park.

Tese de doutoramento, Ciências do Mar, da Terra e do Ambiente, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2015 In this thesis I looked at different components of dispersal in the seagrass Zostera noltii, from the dispersal potential of both sexual and asexual propagules to indirect genetic estimation and landscape genetics analysis. My studies show that the dispersal biology of Z. noltii is very dependent on commonly underestimated asexual dispersal. This asexual LDD is the most parsimonious explanation for the wide distribution of clones in the lagoon and dramatically changes our view of the species’ life history. Furthermore, I propose that the observed lack of association between landscape features and spatial genetic structure is a consequence of this LDD of asexual propagules. The high dispersal capacity of Z. noltii combined with a tidal regime which homogenizes the otherwise complex lagoon habitat, are prevalent over any effects of landscape on gene flow caused by the lagoon complexity as shown by the landscape genetics analyses. Nevertheless, sexual reproduction also affects spatial genetic structure, as the positive kinship between clones within a 3 km range is a signature of restricted seed dispersal. Nesta tese, investiguei as diferentes componentes de dispersão da erva marinha Zostera noltii, desde o potencial de dispersão de propágulos assexuados e sexuados até à sua estimação indirecta através de métodos genéticos e análise de genética paisagistica. O meu estudo demonstra que a dispersão da Z. noltii possui um importante componente assexual, geralmente subestimada. A DLD assexual é a explicação mais parcimoniosa para a larga distribuição de clones na Ria Formosa e altera drasticamente a nossa visão do ciclo de vida da espécie. Para além disso, proponho que a falta de associação observada entre as características da paisagem e a estrutura genética espacial é uma consequência da DLD dos propágulos assexuados. Esta elevada capacidade de dispersão da Z. noltii combinada com o regime de marés que homogeneíza o de outra forma complexo habitat lagunar, predominam sobre quaisquer efeitos da paisagem no fluxo genético causado pela complexidade lagunar. No entanto, há também um efeito da reprodução sexuada na estrutura genética espacial, dado que o grau positivo de parentesco entre clones dentro de uma área de 3 km representa um sinal de dispersão restrita de sementes. FCT – Fundação para a Ciência e Tecnologia - SFRH/BD/68570/2010 A secção de trabalho mostrada no capítulo dois foi financiada pela infraestrutura europeia ASSEMBLE (acordo de subvenção n. 227799) concedidos para o projecto DISPERSE.