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The article reports on the Malaspina Circumnavigation Expedition organized by the Spanish National Research Council, involving 400 scientist and 700 persons with the goal of assessing and exploring the 21st century oceans using new innovation tools. The project also aims to balance cooperation and competition among Spanish marine research groups.

Abstract: Shoot meristematic activity of Mediterranean seagrass Posidonia oceanica has been assessed in eleven different meadows located around Balearic Islands (Spanish Mediterranean). Moreover, in six of them, the meristematic activity has been determined hourly (or every 2 or 3h, depending on the meadow) for at least 24h, with the aim of detecting a possible circadian rhythm in the % of dividing nuclei. Meristematic activity was inferred by applying flow cytometry techniques combined with DNA labeling to determine the percentage of nuclei in each phase of the cell cycle (i.e. G0+G1, S, G2). The percentage of nuclei in G2 phase of the cell cycle reflects the percentage of nuclei that are dividing in a specific moment. In the meristems of vertical shoots of P. oceanica the percentage of nuclei in G2 phase was on average 7±0.11%, and it ranged from 2% to 12% across the meadows studied. The average percentage of nuclei in the G2 phase in P. oceanica meristems is lower than reported for other plants. No circadian rhythms were detected in meristems of P. oceanica. The variability observed for meristematic activity across meadows suggests that it could be used as indicator of seagrass stress and, thus, to assess impacts to meristems before population declines could be observed. [Copyright &y& Elsevier]

Abstract: Uncertainty analyses allow the identification and quantification of the factors that contribute to the potential misclassification of the ecological status of water bodies, helping to improve the sampling design used in monitoring. Here we used a Posidonia oceanica multivariate index (POMI) bio-monitoring dataset covering a total of 81 sites distributed throughout 28 water bodies from the coast of Catalonia, Balearic Islands and Croatia to determine the levels of uncertainty associated with each region and how they change according to the quality status of water bodies. Overall, variability among sites (meadows) within water bodies was the factor that generated the greatest risk of misclassification among the three regions, within which the Balearic Islands had the lowest uncertainty, followed by Croatia and Catalonia. When water bodies classified in good/high quality were separated from those in moderate/poor status classes, we found that the latter displayed higher levels of uncertainty than the former. [Copyright &y& Elsevier]

Rapid warming of the Mediterranean Sea threatens marine biodiversity, particularly key ecosystems already stressed by other impacts such as Posidonia oceanica meadows. A 6-year monitoring of seawater temperature and annual P. oceanica shoot demography at Cabrera Archipelago National Park (Balearic Islands, Western Mediterranean) allowed us to determine if warming influenced shoot mortality and recruitment rates of seagrasses growing in relative pristine environments. The average annual maximum temperature for 2002–2006 was 1 °C above temperatures recorded in 1988–1999 (26.6 °C), two heat waves impacted the region (with seawater warming up to 28.83 °C in 2003 and to 28.54 °C in 2006) and the cumulative temperature anomaly, above the 1988–1999 mean annual maximum temperature, during the growing season (i.e. degree-days) ranged between 0 °C in 2002 and 70 °C in 2003. Median annual P. oceanica shoot mortality rates varied from 0.067 year−1 in 2002 to 0.123 year−1 in 2003, and exceeded recruitment rates in all stations and years except in shallow stations for year 2004. Interannual fluctuations in shoot recruitment were independent of seawater warming ( P>0.05). P. oceanica meadows experienced a decline throughout the study period at an average rate of −0.050±0.020 year−1. Interannual variability in P. oceanica shoot mortality was coupled ( R2>0.40) to seawater warming variability and increasing water depth: shoot mortality rates increased by 0.022 year−1 (i.e. an additional 2% year−1) for each additional degree of annual maximum temperature and by 0.001 year−1 (i.e. 0.1% year−1) for each accumulated degree water temperature remained above 26.6 °C during the growing season. These results demonstrate that P. oceanica meadows are highly vulnerable to warming, which can induce steep declines in shoot abundance as well indicating that climate change poses a significant threat to this important habitat. [ABSTRACT FROM AUTHOR]

Aim A central question in evolutionary ecology is the nature of environmental barriers that can limit gene flow and induce population genetic divergence, a first step towards speciation. Here we study the geographical barrier constituted by the transition zone between the Atlantic Ocean and the Mediterranean Sea, using as our model Cymodocea nodosa, a seagrass distributed throughout the Mediterranean and in the Atlantic, from central Portugal to Mauritania. We also test predictions about the genetic footprints of Pleistocene glaciations. Location The Atlantic–Mediterranean transition region and adjacent areas in the Atlantic (Mauritania to south-west Portugal) and the Mediterranean. Methods We used eight microsatellite markers to compare 20 seagrass meadows in the Atlantic and 27 meadows in the Mediterranean, focusing on the transition between these basins. Results Populations from these two regions form coherent groups containing several unique, high-frequency alleles for the Atlantic and for the Mediterranean, with some admixture west of the Almeria–Oran Front (Portugal, south-west Spain and Morocco). These are populations where only one or a few genotypes were found, for all but Cadiz, but remarkably still show the footprint of a contact zone. This extremely low genotypic richness at the Atlantic northern edge contrasts with the high values (low clonality) at the Atlantic southern edge and in most of the Mediterranean. The most divergent populations are those at the higher temperature range limits: the southernmost Atlantic populations and the easternmost Mediterranean, both potential footprints of vicariance. Main conclusions A biogeographical transition region occurs close to the Almeria–Oran front. A secondary contact zone in Atlantic Iberia and Morocco results from two distinct dispersal sources: the Mediterranean and southernmost Atlantic populations, possibly during warmer interglacial or post-glacial periods. The presence of high-frequency diagnostic alleles in present-day disjunct populations from the southernmost Atlantic region indicates that their separation from all remaining populations is ancient, and suggests an old, stable rear edge. [ABSTRACT FROM AUTHOR]

Abstract: The relationship between sedimentary Fe inputs and net seagrass population growth across a range of Posidonia oceanica meadows growing in carbonate Mediterranean sediments (Balearic Islands, Spain; SE Iberian Peninsula, Spain; Limassol, Cyprus; Sounion, Greece) was examined using comparative analysis. Sedimentary Fe inputs were measured using benthic sediment traps and the net population growth of P. oceanica meadows was assessed using direct census of tagged plants. The meadows examined ranged from meadows undergoing a severe decline to expanding meadows (specific net population growth, from −0.14yr−1 to 0.05yr−1). Similarly, Fe inputs to the meadows ranged almost an order of magnitude across meadows (8.6–69.1mgFem−2 d−1). There was a significant, positive relationship between sedimentary iron inputs and seagrass net population growth, accounting for 36% of the variability in population growth across meadows. The relationship obtained suggested that seagrass meadows receiving Fe inputs below 43mgFem−2 d−1 are vulnerable and in risk of decline, confirming the pivotal role of Fe in the control of growth and the stability of seagrass meadows in carbonate sediments. [Copyright &y& Elsevier]

We measured monthly dissolved oxygen (DO) changes in situ benthic incubations from March 2001 to October 2002 in a Posidonia oceanica meadow and unvegetated sediments of Magalluf Bay (Mallorca Island, Spain) to determine gross primary production (GPP), community respiration (R), and net community production (NCP). From June 2001 to October 2002, we also measured fluxes of dissolved inorganic carbon (DIC) and total alkalinity (TAlk). The yearly integrated metabolic rates based on DO changes show that the P. oceanica communities are net autotrophic while the metabolic rates in the unvegetated benthic communities are nearly balanced. Higher calcium carbonate (CaCO3) cycling, both in terms of production and dissolution, was observed in P. oceanica communities than in unvegetated benthic communities. In the P. oceanica meadow, the annual release of CO2 from net CaCOs production corresponds to almost half of the CO2 uptake by NCP based on DIC incubations. In unvegetated benthic communities, the annual uptake of CO2 from net CaCO3 dissolution almost fully compensates the CO2 release by NCP based on DIC incubations. CaCO3 dynamics is potentially a major factor in CO2 benthic fluxes in seagrass and carbonate-rich temperate coastal ecosystems. [ABSTRACT FROM AUTHOR]

The development of single clones of the seagrassCymodocea nodosawas analysed using a growth model based on the formation of structures limited by diffusive aggregation. The model implemented the measured clonal growth rules (i.e. rhizome elongation and branching rates, branching angle, and spacer length between consecutive shoots) and shoot mortality rate forC. nodosaat Alfacs Bay (Spain). The simulated patches increased their size nonlinearly with time displaying two different domains of growth. Young patches showed a rapid increase with time of the length of rhizome network and the number of living shoots, which depended on rhizome branching rate, and increased the radial patch size (Rg) algebraically with the number of living shoots as Rg ∝ Ns1/Df, being Df the fractal dimension of the patch structure. Patches older than 4 years increased the production of rhizome network and the number of living shoots much more slowly, while their radial patch size behaved as Rg ∝ Ns0.5 resulting from an internal patch compactation. Moreover, the linear growth rate of the simulated patches changed up to 30 fold during patch development, increasing with increasing patch size until patches reached an intermediate size. The modelled patch development was found to closely reproduce the observed patch structure for the species at the Alfacs Bay (Spain). Hence, the growth ofC. nodosapatches initially proceeds with a growth mode controlled by the branching pattern (branching frequency and angle) of the species, producing sparse and elongated patches. Once patches exceed 4–5 years of age and contained>500 shoots, becoming dense and circular, they shifts to a growth model typical of compact structures. These results explain previously unaccounted evidence of the emergence of nonlinear patch growth from simple clonal growth rules, and highlight the importance of branching frequency and angles as critical determinants of the space occupation rate of seagrasses and probably other clonal plants. [ABSTRACT FROM AUTHOR]

Microbial activity was assayed in sediments under five nutrient-limited Posidonia oceanica meadows on the north-east coast of Spain by measuring potential DMSO reduction to dimethylsulfide (DMS) throughout an annual cycle. Nutrient enrichment of the sediments was used to examine the importance of nutrient availability for potential DMSO reduction. DMSO reduction was observed in all the sediments analysed. Values were higher under anaerobic conditions, and low in spring when seagrass uptake removed most of the interstitial sediment phosphorus. DMSO reduction was correlated with α-glucosidase activity suggesting a link with other microbial activities. Nutrient additions significantly increased DMSO reduction in the meadows studied. The extent of the response varied substantially over the year and was highest during November–December. Microbial DMSO reduction was coupled with nutrient cycles like other bacterial activities. This suggests a possibly important role of nutrient additions in bacterial activity in Mediterranean seagrass sediments. [Copyright &y& Elsevier]

Sulfur cycling was investigated in carbonate-rich and iron-poor sediments vegetated with Posidonia oceanica in oligotrophic Mediterranean around Mallorca Island, Spain, to quantify sulfate reduction and pools of sulfide in seagrass sediments. The oxygen penetration depth was low (< 4.5 mm) and sulfate reduction rates were relatively high (0.7–12 mmol m-2d-1). The total pools of reduced sulfides were remarkably low (< 5 mol S m-2) indicating a fast turnover of reduced sulfides in these iron-poor sediments. The sulfate reduction rates were generally higher in vegetated compared to bare sediments possible due to enhanced sedimentation of sestonic material inside the seagrass meadows. The sulfate reduction rates were positively correlated with the seasonal variation in water temperature and negatively correlated with the shoot density indicating that the microbial activity was controlled by temperature and release of oxygen from the roots. The pools of reduced sulfides were low in these iron-poor sediments leading to high oxygen consumption for reoxidation. The sediments were highly anoxic as shown by relatively low oxygen penetration depths (< 4.5 mm) in these low organic sediments. The net shoot recruitment rate was negative in sediments enriched with organic matter, suggesting that organic matter enrichment may be an important factor for seagrass status in these iron-depleted carbonate sediments. [ABSTRACT FROM AUTHOR]

Abstract: Polar marine ecosystems have global ecological and economic importance because of their unique biodiversity and their major role in climate processes and commercial fisheries, among others. Portugal and Spain have been highly active in a wide range of disciplines in marine biology of the Antarctic and the Arctic. The main aim of this paper is to provide a synopsis of some of the results and initiatives undertaken by Portuguese and Spanish polar teams within the field of marine sciences, particularly on benthic and pelagic biodiversity (species diversity and abundance, including microbial, molecular, physiological and chemical mechanisms in polar organisms), conservation and ecology of top predators (particularly penguins, albatrosses and seals), and pollutants and evolution of marine organisms associated with major issues such as climate change, ocean acidification and UV radiation effects. Both countries have focused their polar research more in the Antarctic than in the Arctic. Portugal and Spain should encourage research groups to continue increasing their collaborations with other countries and develop multi-disciplinary research projects, as well as to maintain highly active memberships within major organizations, such as the Scientific Committee for Antarctic Research (SCAR), the International Arctic Science Council (IASC) and the Association of Polar Early Career Scientists (APECS), and in international research projects. [Copyright &y& Elsevier]