Publications

Association for the Sciences of Limnology and Oceanography (ASLO) Summer Meeting, 5-10 June 2016, Santa Fe, New Mexico

ABSTRACT Microbial eukaryotes are key components of the ocean plankton. Yet, our understanding of their community composition and activity in different water layers of the ocean is limited, particularly for picoeukaryotes (0.2-3 µ m cell size). Here we examined the picoeukaryotic communities inhabiting different vertical zones of the tropical and subtropical global ocean: surface, deep chlorophyll maximum, mesopelagic (including the deep scattering layer and minimum oxygen zone) and bathypelagic. Communities were analysed by high-throughput sequencing of the 18S rRNA gene, as represented by DNA (community structure) and RNA (metabolic expression), followed by delineation of Operational Taxonomic Units (OTUs). We found a clear stratification of the picoeukaryotic communities along the water column, with two differentiated assemblages corresponding to the sunlit and dark ocean. Specific taxonomic groups either increased or decreased their abundances with depth. We used the rRNA:rDNA ratio of each individual OTU as a proxy of its metabolic activity. The highest relative activity was found in the mesopelagic layer for most taxonomic groups, and the lowest in the bathypelagic. Overall, our results characterize the change in community structure and activity of picoeukaryotes in the global-ocean water column, suggesting that the mesopeagic layer is a hot-spot of picoeukaryotic activity.

Two prime issues can detrimentally affect animals that have been equipped with tags: (i) the effect of the capture and restraint process; and (ii) the effect of the tag itself. This work examines some of the issues surrounding quantification of tag effects on wild animals for both restrained and free-living animals. A new method to quantify stress effects based on monitoring ventilation rates in relation to activity is suggested for restrained animals which may help improve the practice of handling animals. It is also suggested that various metrics, many derived from accelerometers, can be examined in tagged wild animals to examine the change in behaviors over time with a view to having a better understanding of welfare issues, assuring the quality of recorded data and informing best practice.

Mangrove ecosystems provide important ecological benefits and ecosystem services, including carbon storage and coastline stabilization, but they also suffer great anthropogenic pressures. Microorganisms associated with mangrove sediments and the rhizosphere play key roles in this ecosystem and make essential contributions to its productivity and carbon budget. Understanding this nexus and moving from descriptive studies of microbial taxonomy to hypothesis-driven field and lab studies will facilitate a mechanistic understanding of mangrove ecosystem interaction webs and open opportunities for microorganism-mediated approaches to mangrove protection and rehabilitation. Such an effort calls for a multidisciplinary and collaborative approach, involving chemists, ecologists, evolutionary biologists, microbiologists, oceanographers, plant scientists, conservation biologists, and stakeholders, and it requires standardized methods to support reproducible experiments. Here, we outline the Mangrove Microbiome Initiative, which is focused around three urgent priorities and three approaches for advancing mangrove microbiome research.

Abstract Anthropogenic sea level rise (SLR) presents one of the greatest risks to human lives and infrastructures. Coastal vegetated ecosystems, that is, tidal marshes, seagrass meadows, and mangrove forests, elevate the seabed through soil accretion, providing a natural coastline protection against SLR. The soil accretion of these ecosystems has never been assessed in hot desert climate regions, where water runoff is negligible. However, tropical marine ecosystems are areas of intense calcification that may constitute an important source of sediment supporting seabed elevation, compensating for the lack of terrestrial inputs. We estimated the long‐term ( 14 C‐centennial) and short‐term ( 210 Pb‐20th century) soil accretion rates (SARs) and inorganic carbon (C inorg ) burial in coastal vegetated ecosystems of the Saudi coasts of the central Red Sea and the Arabian Gulf. Short‐term SARs (±SE) in mangroves of the Red Sea (0.27 ± 0.22 cm/year) were twofold the SLR for that region since 1925 (0.13 cm/year). In the Arabian Gulf, only mangrove forest SAR is equivalent to local SLR estimates for the period 1979–2007 (0.21 ± 0.09 compared to 0.22 ± 0.05 cm/year, respectively). Long‐term SARs are comparable or higher than the global estimates of SLR for the late Holocene (0.01 cm/year). In all habitats of the Red Sea and Arabian Gulf, SARs are supported by high carbonate accretion rates, comprising 40% to 60% of the soil volume. Further studies on the role of carbonates in coastal vegetated ecosystems are required to understand their role in adaptation to SLR.

This paper presents a study assessing the effect of development technology choices on the accessibility quality of web pages. We used an off-the-shelf tool to identify technologies over a set of 1669 pages, each from a different domain. We have focused, in particular, in programming languages, Web and JavaScript frameworks, and content management systems categories. Simultaneously, we used an automatic accessibility evaluation tool to assess the accessibility of those pages. The study shows statistical evidence that some technologies lead to more accessible pages, within all categories.

In March 2012 we collected 3-replicated sediment cores (9 cm diameter and 12-15 cm long) per restored site along the planting chronosequence (i.e. years 1994, 1997, 2003, 2004, 2006). Similarly, we collected 3 sediment cores in two bare sites, previously colonized by seagrasses, and in a large seagrass patch that survived the disturbances in the second half of the 20th Century that we considered a mature and thus reference meadow. We measured sediment bulk density and organic matter content and carbon stocks along all sediment cores sliced at 1 cm interval. Organic carbon content (% Corg) was estimated from loss of ignition (% LOI) at 550oC for 5 h using the empirically fitted equation for Oyster Harbour sediments,Log % Corg = -0.62 + (1.33 * Log % LOI) SEintercept = 0.01, SEslope =0.10, N = 55, R2 = 0.77, P<0.0001 We analyzed the ƌ3C of the organic carbon in the top 3 cm sediment layer (ƌ13Csediment) along the chronosequence to estimate the fraction of seagrass (X) and sestonic (1-X) deposition as ƌ13Csediment = [X . Log % Corg = -0.62 + (1.33 * Log % LOI) SEintercept = 0.01, SEslope =0.10, N = 55, R2 = 0.77, P<0.0001 We analyzed the ƌ3C of the organic carbon in the top 3 cm sediment layer (ƌ13Csediment) along the chronosequence to estimate the fraction of seagrass (X) and sestonic (1-X) deposition as ƌ13Csediment = [X . ƌ13Cseagrass] + [(1-X) . ƌ13Cseston] being ƌ13Cseagrass -9.65 ‰ and ƌ13Cseston -22 ‰ (Dauby 1989).

Trabajo presentado en Arctic Frontiers 2011, Arctic Tipping Points, celebrado en Tromso (Noruega), del 23 al 28 de enero de 2011. El libro de abstracts se publico como: 2011 Abstracts. Arctic Frontiers. The Arctic in the Earth System Perspective: the role of tiping points. Tromso: [University of Tromso, 2011]

Seagrasses colonized the sea on at least three independent occasions to form the basis of one of the most productive and widespread coastal ecosystems on the planet. Here we report the genome of Zostera marina (L.), the first, to our knowledge, marine angiosperm to be fully sequenced. This reveals unique insights into the genomic losses and gains involved in achieving the structural and physiological adaptations required for its marine lifestyle, arguably the most severe habitat shift ever accomplished by flowering plants. Key angiosperm innovations that were lost include the entire repertoire of stomatal genes, genes involved in the synthesis of terpenoids and ethylene signalling, and genes for ultraviolet protection and phytochromes for far-red sensing. Seagrasses have also regained functions enabling them to adjust to full salinity. Their cell walls contain all of the polysaccharides typical of land plants, but also contain polyanionic, low-methylated pectins and sulfated galactans, a feature shared with the cell walls of all macroalgae and that is important for ion homoeostasis, nutrient uptake and O2/CO2 exchange through leaf epidermal cells. The Z. marina genome resource will markedly advance a wide range of functional ecological studies from adaptation of marine ecosystems under climate warming, to unravelling the mechanisms of osmoregulation under high salinities that may further inform our understanding of the evolution of salt tolerance in crop plants.