Assessing sea grass meadows condition at “El Río” Special Area of Conservation off “La Graciosa e Islotes del Norte de Lanzarote” Marine Reserve

Cymodosea nodosa meadows, known as ‘sebadales’ or ‘manchones’ at Canary Islands, represent EUNIS habitat type code A5.5311, called Macaronesian Cymodocea beds. As it’s described at European Union Habitats Directive (92/43/CEE) Annex 1, sea grass meadows belong to 1110 Sandbanks which are slightly covered by seawater all the time, within Natura 2000 Network. Several ‘sebadales’ throughout the archipelago are included in this Network as Special Areas of Conservation. Cymodosea nodosa is regionally included within the Canary Islands Protected Species List (Ley 4/2010), as a species ‘of interest to ecosystems of Canary Islands”, is usually found at a narrow depth range (10 to 20 m of depth) and, on the whole, best structured meadows are settled at sheltered bays, away from wave and current beating, flimsier at exposed areas. Deeper meadows are also sparser, being C. nodosa replaced by green algae Caulerpa prolifera and Caulerpa racemosa, although mixed algae-sea grass meadows are often found at different depths. The project Assessment of marine flora (‘sebadal’, ma¨erl, ‘mujo’) of ‘La Graciosa e Islotes del Norte de Lanzarote’ Marine Reserve, funded by ‘Viceconsejer´ıa de Pesca y Aguas de la Consejer´ıa de Agricultura, Ganader´ıa, Pesca y Aguas’, Canary Islands Government, has had the aim of assessing sea grass meadows condition and distribution at ‘El R´ıo’ Natura 2000 Network Special Area of Conservation, the channel between La Graciosa and Lanzarote. ‘LA GRACIOSA 1311’ cruise was performed within the framework of the project. First of all previous information on sea grass shallow distribution (up to a depth of 20 m) in the study area was reviewed. Afterwards, a tugged underwater video camera was used onboard of the Marine Reserve Surveillance Vessel to update cartographic info performing a grid of sampling stations, covering previously known distribution limits and verifying current presence/absence data and density. Furthermore, population parameters were obtained in order to assess ‘sebadal’ condition. Fixed stations were selected in regards to this process, and methodology applied on them was as follows: five radial arranged transects were performed, identifying fragmentation (it estimates meadow continuity regarding observed cover), density (mean value of several shoots number counts with 20 x 20 cm grids placed every 2 m), height (mean value in cm of 10 independent samples by transect) and fish and macroinvertebrate species richness for each transect. Graphic picture of sea grass density was made depending on two levels: low density level transects ( 10 shoots/grid ( 50 shoots/m2) and medium density level transects ( 10 shoots/grid ( 50 shoots/m2). Main study result is an estimate for the study region (‘El R´ıo’) and time of year of Cymodocea nodosa population total distribution cover which comes to 1.640.076 m2, including a higher density ‘sebadal’ of 178.256 m2

Effects of the anthropogenics pressures (marine litter) on the coastal ecosystems of the Marine Reserve “Isla de La Graciosa e islotes del norte de Lanzarote”

The European Marine Strategy Framework Directive (2008/56/EC) considers marine litter as one of its environmental descriptors, requiring the development and standardization of criteria and methodologies for its use to test the good environmental status of marine conditions. The assessment of the impact caused by litter accumulation in the shoreline lacked specific monitoring planning and had not been systematically performed to date in Canary Islands. During the project ”Evaluation of the effect of the anthropogenic pressures (marine litter in beaches and alteration of shallow seabed by boats anchoring) on the coastal ecosystems of the “Marine Reserve of Isla de La Graciosa e islotes del norte de Lanzarote (MRLG)” developed with the financial help of the Canary Islands Government (Council of Agriculture, Ranching, Fishing and Waters), two surveys were carried out, ”LA GRACIOSA 1310” and “LA GRACIOSA 1311”, both developed at MRLG and its vicinities. The aim has been to depict MRLG shoreline and to locate marine litter accumulation points the most, contributing with some tools to assess and manage the coastal ecosystems of the marine reserve. Total shoreline sampled at both surveys together was 38326 m, 1834 m at Alegranza, 1366 m at Monta˜na Clara, 24656 m at La Graciosa Island, and the rest, 10470 m, at the Lanzarote’s shoreline portion bathed by MRLG waters. Shoreline sampling was made qualitatively sorting the sampling stations, according to litter presence and distribution, by means of a upward numerical coding related to the type of waste or garbage found. Moreover, each station was additionally depicted according to the type of substrate as well as to the prevailing type of waste, defining what we named “transects”. To validate methodology to European standards, a more exhaustive experimental sampling was made in four transects identified as high density or high concentration of marine litter, following guidelines of a method developed for OSPAR maritime area during the first half of 2000 decade (OSPAR, 2007). It involves evaluating the possibilities and needs of adjustment of this methodology to the particular conditions of our region (Gonz´alez, et al., 2013 a and b). As preliminary results, the spatial distribution of garbage coastal accumulation will be shown in a cartographic base, expressed as relative abundance by island, according to a 4 degrees scale (no litter, low, medium and high litter presence) and according to the dominant kind of garbage in each transect. An example with one of the most densely occupied with trash transects is shown to illustrate a sampling method without the requirement of trash collection. This method uses a sampling unit of 1x1 m grid, divided in 10x10 cm subgrids. This grid is set parallel to sampling direction repeatedly. Distance between grids is determined by a randomizing software. Sampling direction zigzags from sea border to beach back shore, making 45° degrees angles. Subgrids occupied by trash are counted once the grid is set. Waste is depict and identified following a guide developed for this purpose by OSPAR in 2010

Désignation de zones littorales, sélection et évaluation d’indicateurs

En prens

Caracterización fenotípica y genotípica de doce rizobios aislados de diversas regiones geográficas de Venezuela

Rhizobial taxonomy and systematics have progressed substantially, nevertheless, few studies have been developed on venezuelan species. This study evaluated the phenotypic and genetic variation between 12 venezuelan indigenous rhizobial isolates and 10 international referential strains, by phenotypical traits and DNA molecular markers. In this regard, a PCR-RFLP of the 16S rDNA gene, the presence of large plasmids, metabolic assays in solid media, salinity resistance, pH and temperature growth conditions, and intrinsic antibiotic resistance were assayed. In reference to the phenotypic attributes, we recognized three main groups: A group I, which comprised all the strains metabolizing between 67.5%-90% of the C and N sources. They were also acid-tolerant, as well as acid producers, capable of growing at 40°C and in high salinity conditions (2-2.5% NaCl). With regard to the antibiotic sensitivity, this group was susceptible to a 30% of the antibiotic assayed. Strains belonging to Group II exhibited a lower salt tolerance (0.1-1.5%NaCl), as well as a lower acid tolerance, since they grew well at pH values equal or higher than 5.0. This group appeared to be resistant to all of the antibiotics assayed and only metabolized between 52.5%-82.5% of the C and N sources. Group III was represented by a single bacterial strain: it has a extremely low salt tolerance (0.1% NaCl). This strain grew at a pH equal or higher than 5.6, was susceptible to 50% of the antibiotics assayed and metabolized 72% of the C and N sources. On the basis of a PCR- RFLP of the 16S rDNA, three groups were also obtained. Members of the group A showed a close resemblance to Rhizobium tropici CIAT 899 and Sinorhizobium americanum CFN-EI 156, while Group B was closely related to Bradyrhizobium spp. Group C, was also represented by only one isolate. The Trebol isolate, was the only one strain able to form nodules and does not appear to be related to any of the referential rhizobial strains, suggesting a possible symbiotic horizontal gene transfer. Finally, in this work, there are evidences of a genetic diversity in the venezuelan rhizobial strains. A different geographical origin is perhaps an important factor affecting the diversity of the indigenous rhizobia in this study

Caracterización fenotípica y genotípica de doce rizobios aislados de diversas regiones geográficas de Venezuela

Rasgos fenotípicos y marcadores moleculares de ADN se utilizaron para investigar la variación fenotípica y genética entre 12 aislados rizobianos venezolanos y 10 cepas de referencia internacionales. Para ello, se realizó un PCR-RFLP del gen rDNA 16S, la presencia de plásmidos grandes, análisis metabólicos en medios sólidos, resistencia a la salinidad, condiciones del crecimiento a diferentes pH y temperaturas y la resistencia intrínseca a antibióticos. En referencia a las cualidades fenotípicas, se diferenciaron tres grupos principales, un grupo I que abarcó a todas aquellas cepas que metabolizaban entre 67.5% y 90% de las fuentes de C y de N. También eran tolerantes a la acidez y productoras de ácido, capaces de crecer a 40ºC y a altas condiciones de salinidad (NaCl 2-2.5%). Con respecto a la sensibilidad a antibióticos, este grupo era susceptible a un 30% de los antibióticos empleados. Las cepas que pertenecen al grupo II exhibieron una tolerancia salina más baja (0.1- 1.5%NaCl), así como una menor tolerancia a la acidez, puesto que crecieron bien en valores de pH iguales o mayores a 5.0. Este grupo era resistente a todos los antibióticos probados y metabolizaban solamente entre 52.5%-82.5% de las fuentes de C y de N. Una sola cepa bacteriana representó al grupo III, con una baja tolerancia salina (0.1% NaCl). Este aislado creció a un pH mayor o igual a 5.6, era susceptible a 50% de los antibióticos probados y metabolizó el 72% de las fuentes de C y de N. Al tener como base el PCR-RFLP del 16S rDNA, se diferenciaron también tres grupos. Los miembros del grupo A demostraron una estrecha relación con Rhizobium tropici CiAT 899 y Sinorhizobium americanum CFN-Ei156, mientras que el grupo B está estrechamente vinculado a Bradyrhizobium spp. El grupo C, está representado por solo un aislado. El aislado Trebol, fue la única cepa capaz de formar nódulos y no aparece relacionado con ninguna cepa de referencia, y sugiere una transferencia horizontal de genes simbióticos. Finalmente, en este trabajo se evidencia una diversidad genética en las cepas rizobianas venezolanas. El origen geográfico diverso de estas cepas, quizás sea un factor importante que influencie la diversidad de los rizobios indígenas utilizados en este estudio

The underreported presence of the subtidal seagrass Cymodocea nodosa in rocky intertidal pools of the Canary Islands

During 2014, 21 patches of Cymodocea nodosa were found in intertidal pools in Fuerteventura (Canary Islands). Pool substratum was mixed sand and rock, but mostly dominated by stone bottoms. Most plants were established with fully exposed rhizomes, filling small fissures without sediment. During subsequent sampling surveys between 2016 and 2019, the presence of these patches was consistent over time in an environment normally considered extreme for most seagrasses. As far as we know, the presence of Cymodocea nodosa patches in intertidal areas has not been observed previously in the Canary Islands. If the presence of C. nodosa patches in these intertidal pools is stable over time, it raises new environmental management and conservation questions for this endangered species in the Canary Islands. In addition, due to the current regression of C. nodosa meadows, our observations represent an optimistic perspective that underline the need for specific monitoring plans for this ecosystem