Restoration of Cymodocea nodosa (Uchria) Ascherson seagrass prairies through seed propagation. Seed storage and growth of seedlings as affected by inorganic nutrients and plant hormones.

[EN] In the frame of the restoration of natural populations of Cymodocea nodosa of the Canary Islands, seeds are being collected at natural populations where germination is rather scarce and seasonal after dormancy. We have developed techniques of propagation in vitro of collected seeds, consisting in forced seed germination and seedlings propagation to obtain mature 20-30 cm plantlet, which eventually are being used for restoration. In order to improve the developed methodology, several experiments were conducted to adjust conditions for seed storage under different regimes of temperature without loosing germinative potential, fertilize during propagation with controlled released NPK fertilizers, and increase growth by dipping seedlings in solutions of the most common plant hormones.

Restoration of Cymodocea nodosa (Uchria) Ascherson seagrass prairies through seed propagation. Germination in vitro, plantlet acclimation and transplanting to natural meadows.

[EN] The seagrass Cymodocea nodosa (Ucria) Ascherson is the most abundant seagrass species in the Canary Islands (Spain), where it forms dense submerged, ecologically relevant communities as stable and protected habitats. As with other seagrasses, concern has arisen due to a decline in the number and extension of the communities as the result of adverse activities in coastal areas. Seed germination and planting are assumed as cost-effective method for restoration. In the frame of the restoration of natural populations of Cymodocea nodosa, pilot experiences not tested so far in the Canary Islands have been carried out to developed in vitro techniques to produce viable seedlings and its transference to the natural environment.

Ocean Ultrasonic Shear and Compression Viscosities

[EN]A comprehensive description of ocean molecular flow and deformation is provided with the help of hydrodynamic and ultrasonic principles. Hydrodynamic computation of true or natural viscosities shows that ocean shear viscosity (?G), compression viscosity (?K), and extensional viscosity (?E) are interrelated. There are no experimental methods available for the in situ measurement of these viscosities. Sound absorption coefficients (? obs) allow to know the ultrasonic shear (?UG), compression (?UK), and longitudinal (?L) viscosities, which decrease with increasing frequency and increase with increasing temperature, the flow activation energies having nearly equivalent values; pressure (depth) increase/decrease them at low/high frequencies. The viscosities ?* UG, ?* UK, ?* L are approached at about 1000 KHz. They decrease with temperature and pressure, and increase with salinity. The ?*UG becomes equal to the true shear viscosity ? G at the viscosity ratio ? = ?UK / ?UG = 0.