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Este artículo contiene 13 páginas, 5 figutas, 3 tablas., The resilience of an ecological unit encompasses resistance during adverse conditions and the capacity to recover. We adopted a ‘resistance-recovery’ framework to experimentally partition the resilience of a foundation species (the seagrass Cymodocea nodosa). The shoot abundances of nine seagrass meadows were followed before, during and after simulated light reduction conditions. We determined the significance of ecological, environmental and genetic drivers on seagrass resistance (% of shoots retained during the light deprivation treatments) and recovery (duration from the end of the perturbed state back to initial conditions). To identify whether seagrass recovery was linearly related to prior resistance, we then established the connection between trajectories of resistance and recovery. Finally, we assessed whether recovery patterns were affected by biological drivers (production of sexual products—seeds—and asexual propagation) at the meadow-scale. Resistance to shading significantly increased with the genetic diversity of the meadow and seagrass recovery was conditioned by initial resistance during shading. A threshold in resistance (here, at a ca. 70% of shoot abundances retained during the light deprivation treatments) denoted a critical point that considerably delays seagrass recovery if overpassed. Seed densities, but not rhizome elongation rates, were higher in meadows that exhibited large resistance and quick recovery, which correlated positively with meadow genetic diversity. Our results highlight the critical role of resistance to a disturbance for persistence of a marine foundation species. Estimation of critical trade-offs between seagrass resistance and recovery is a promising field of research to better manage impacts on seagrass meadows., This work was funded by a project (RESIGRASS, CGL2014- 58829) supported by the Secretaría de Estado de Investigación, Desarrollo e Innovación (MINECO, Government of Spain).

Zarranz Elso, M.; Manent, P., and Robaina, R.R., 2018. Zostera noltii in the Canary Islands: A genetic description for conservation purposes. The extremely delicate situation affecting the seagrass Zostera noltii in the Canary Islands (listed as ‘threatened with extinction') requires urgent measures to ensure its preservation. The genetic or genotypic description of populations and knowledge about their connectivity are important genetic issues that should be taken into account to accomplish appropriate conservation and restoration programmes, particularly for threatened habitats or species. Therefore, a genetic characterisation of the single remaining meadow located on the coast of Lanzarote was conducted using nine microsatellite loci, and its genetic relationship with the geographically closest Moroccan populations was studied for restoration purposes. Results showed that the Lanzarote population has recently suffered a significant reduction in effective population size and presents low levels...

Seagrasses constitute a key coastal habitat world-wide, but are exposed to multiple perturbations. Understanding elements affecting seagrass resistance to disturbances is critical for conservation. Distinct biogeographical scenarios are intrinsically linked with varying ecological and evolution backgrounds shaped across millennia. We addressed whether the resistance (change in shoot abundances) and performance (change in leaf morphology and growth) of the seagrass Cymodocea nodosa to a local stressor, light reduction, varied across three regions (Southeast Iberia, the Balearic Sea, and the Canaries) within the temperate northern Atlantic realm. We hypothesized that distinct biogeographical scenarios, in terms of distinct ecological/environmental conditions and genetic diversity of meadows, would affect seagrass resistance and performance, with flow-on effects on associated epifauna. The same experiments, in terms of shading intensities, timing and duration, were replicated at three seagrass meadows within each region. Results demonstrated inter-regional variation in the resistance and performance of C. nodosa. Under moderate and high shading, shoot abundance was abruptly decreased, relative to controls, in the Canaries with concurrent, but less accentuated, changes in leaf morphology and no changes in growth. In the other two regions, however, moderate and high shading had a negligible effect on shoot abundance, leaf morphology, and growth. Shading had no overall effect over the total abundance and assemblage structure of epifauna; these faunal attributes, however, varied between regions. Low seagrass resistance at the Canaries is linked with the peripheral distribution of the species there, favouring isolation and decreased genetic diversity. Synthesis. Different biogeographical scenarios shape seagrass resistance to local perturbations. From a conservation perspective, if resistance differs among biogeographical scenarios, universal conservation rules for seagrasses are challenging., This work was funded by a project (RESIGRASS, CGL2014‐58829) supported by the Secretaría de Estado de Investigación, Desarrollo e Innovación (MINECO, Government of Spain) to F.T. and F.T.

Seagrasses are key habitat-forming species of coastal areas. While previous research has demonstrated considerable small-scale variation in seagrass abundance and structure, studies teasing apart local from large-scale variation are scarce. We determined how different biogeographic scenarios, under varying environmental and genetic variation, explained variation in the abundance and structure (morphology and biomass allocation), epiphytes and sexual reproduction intensity of the seagrass Cymodocea nodosa. Regional and local-scale variation, including their temporal variability, contributed to differentially explain variation in seagrass attributes. Structural, in particular morphological, attributes of the seagrass leaf canopy, most evidenced regional seasonal variation. Allocation to belowground tissues was, however, mainly driven by local-scale variation. High seed densities were observed in meadows of large genetic diversity, indicative of sexual success, which likely resulted from the different evolutionary histories undergone by the seagrass at each region. Our results highlight that phenotypic plasticity to local and regional environments need to be considered to better manage and preserve seagrass meadows., This research was supported by a Doctoral fellowship from Universidad de Los Lagos (Chile) to Julia Máñez-Crespo and the work was funded by a project (RESIGRASS, CGL 2014-58829) supported by the Secretaría de Estado de Investigación, Desarrollo e Innovación (MINECO, Government of Spain) to F. Tomas and F. Tuya.

Genetic diversity in clonal organisms includes two distinct components, (i) the diversity of genotypes or clones (i.e. genotypic richness) in a population and (ii) that of the alleles (i.e. allelic and gene diversity within populations, and differentiation between populations). We investigated how population differentiation and genotypic components are associated across a gradient of eutrophication in a clonal marine plant. To that end, we combined direct measurements of sexual allocation (i.e. flower and seed counts) and genotypic analyses, which are used as an estimator of effective sexual reproduction across multiple generations. Genetic differentiation across sites was also modelled according to a hypothesis here defined as isolation-by-demography, in which we use population-specific factors, genotypic richness and eutrophication that are hypothesized to affect the source-sink dynamics and thus influence the genetic differentiation between a pair of populations. Eutrophic populations exhibited lower genotypic richness, in agreement with lower direct measurements of sexual allocation and contemporaneous gene flow. Genetic differentiation, while not explained by distance, was best predicted by genotypic richness and habitat quality. A multiple regression model using these two predictors was considered the best model (R(2) = 0.43). In this study, the relationship between environment and effective sexual-asexual balance is not simply (linearly) predicted by direct measurements of sexual allocation. Our results indicate that population-specific factors and the isolation-by-demography model should be used more often to understand genetic differentiation.

Sharing experiences and results among scientists and managers working on seagrass restoration was the main objective of the first European Seagrass Restoration Workshop that gathered researchers from around Europe. The meeting was the first forum in Europe that allowed for scientists, NGOs, and managers to interact and share their experiences relating to seagrass restoration and management. The results show that none of the seagrass restoration programs developed in Europe by the participants during the last 10 years was successful. Furthermore, an informal review of data published in seagrass restoration success, showed that the results reported were biased because they were mostly based on a very short monitoring period (i.e., This research was funded by the European commission through the LIFE Biomares project (LIFE 06 NAT/P/192)

Growth and reproductive cycle of the prawn, Palaemon adspersus were studied in Fornells Bay from April 2002 to March 2003. Samples caught using a lift net showed that abundance is markedly seasonal, with peaks in autumn and winter. P. adspersus showed distinct sexual dimorphism, the females being larger than the males. The K coefficient of the VBGF (Von Bertalanffy Growth Formula) was higher in the females (2.065 year−1 for females and 1.076 year−1 for males) and the same applies to L ∞ coefficient of the VBGF (47.8 mm in females and 34.14 mm in males). Ovigerous females were found from March to August. However, the low percentage of ovigerous females found in the study area suggests that reproduction and incubation do not occur at the study site. Also, as the ovary shows activity during the whole year cycle, it is not possible to distinguish a discrete reproductive period. El crecimiento y el ciclo reproductor de Palaemon adspersus fueron estudiados en la bahia de Fornells entre Abril de 2002 y Marzo de 2003. Las muestras obtenidas con una red por elevacion indican una marcada variacion estacional, con mayores abundancias en otono e invierno. P. adspersus presenta dimorfismo sexual, siendo de mayor talla las hembras. Los parametros de crecimiento calculados fueron superiores en hembras. El valor del coeficiente K de la VBGF (Formula de crecimiento de Von Bertalanffy fue 2.065 ano−1 para las hembras y 1.076 ano−1 para los machos. En el caso de L ∞, fueron 47.8 mm en hembras y 34.14 mm en machos. Se han encontrado hembras ovigeras entre Marzo y Agosto. En cualquier caso, el bajo porcentaje de hembras ovigeras encontradas sugiere que la reproduccion e incubacion no se desarrollan en el area de estudio. Esto unido a que la actividad del ovario se mantiene durante todo el ano no permite discernir un periodo reproductor claro.

The Azorean barnacle, Megabalanus azoricus (Pilsbry, 1916), is a Macaronesian endemic whose obscure taxonomy and the unknown relationships among forms inhabiting isolated Northern Atlantic oceanic islands is investigated by means of molecular analysis herein. Mitochondrial data from the 16S rRNA and COX1 genes support its current species status, tropical ancestry, and the taxonomic homogeneity throughout its distribution range. In contrast, at the intraspecific level and based on control region sequences, we detected an overall low level of genetic diversity and three divergent lineages. The haplogroups α and γ were sampled in the Azores, Madeira, Canary, and Cabo Verde archipelagos; whereas haplogroup β was absent from Cabo Verde. Consequently, population analysis suggested a differentiation of the Cabo Verde population with respect to the genetically homogenous northern archipelagos generated by current oceanographic barriers. Furthermore, haplogroup α, β, and γ demographic expansions occurred during the interglacial periods MIS5 (130 Kya - thousands years ago -), MIS3 (60 Kya), and MIS7 (240 Kya), respectively. The evolutionary origin of these lineages is related to its survival in the stable southern refugia and its demographic expansion dynamics are associated with the glacial-interglacial cycles. This phylogeographic pattern suggests the occurrence of genetic discontinuity informative to the delimitation of an informally defined biogeographic entity, Macaronesia, and its generation by processes that delineate genetic diversity of marine taxa in this area.

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. © 2008 The Authors.