Morphogenesis of the Ourense plains:(NW of Spain)

[EN] We present a geomorphological analysis of Ourense Province (NW Spain) characterized by: a general narrowing of the fluvial network, highlands with smooth reliefs partially eroded and lowlands with residual reliefs, several extensive plains of erosion frequently limited by fractures -among which Tertiary grabens are inserted-, some ?Hollow Surface?-type morphology, absence of sedimentary deposits outside the grabens, and a generalized outcrop of the Hercynian Massif substratum. Traditionally, this ?piano?s keyboard morphology? has been interpreted as expression of block tectonics in tensile regimen; instead we suggest the existence of: an isostatic upheaval simultaneous to a sequence of tectonic pulses of compressive regimen with activity in favour of transcurrent faults, a General Surface (R600), several plains that present a ?Hollow Surface?-type morphology (R1600 R1400 R1000), a generalized alteration that correspond to a same process of decomposition associated to fluctuating conditions of redox equilibrium, a erosional terraces related principaly to the palaeo-fluvial nets; moreover, we propose the existence of two morphoestructural lineament: the first one represented by the Fault of Vila Real (NE-SW) -a ramification of the ?Basal Pyrenean Overthrust?-, that would have been active at an early moment of the tectonic sequence with a left transcurrent fault, secondly the lineament represented by the Fault of Maceda (NNW-SSE) that would be related to the ?Fault System NW-SE? and would have produced a right transcurrent fault during a late tectonic pulse.

Embryonic and larval development of haliotis tuberculata coccinea reeve: an indexed micro-photographic sequence

[EN] First description of the complete embryo and larval development of the Canarian abalone (Haliotis tuberculata coccinea Reeve.) was conducted along 39 stages from fertilization to the appearance of the third tubule on the cephalic tentacles and illustrated in a microphotographic sequence. Eggs obtained by induced spawning with hydrogen peroxide from the GIA captive broodstock were stocked at a density of 10 eggs/mL and kept at 23 0.5 BC for 62 h until the formation of the third tubule. Live eggs and larvae were continuously observed on a 24 h basis at a 3400 magnification under transmitted light. At each stages, specific morphological features, illustrated by microscopic photographs, were described, as well as the time required for their apparition. Fertilized eggs diameter was 205 8 mm (mean SD), whereas length and width of larvae ready to undergo metamorphosis were 216.6 5.3 mmand 172 8.8 mm, respectively. Knowledge on the larval morphological development acquired through this study will contribute to the improvement of larval rearing techniques for this abalone species.