Colour morphotypes of Elysia timida (Sacoglossa, Gastropoda) are determined by light acclimation in food algae

Elysia timida (Risso, 1818) colonizing the shallow waters of the Mar Menor Lagoon (Spain) exhibit a brown and a green morph. It was hypothesised that these morphs were the result of feeding preferentially on brown and green algae, respectively. E. timida and its potential food sources, Acetabularia acetabulum (Chlorophyta) and Halopteris filicina (Heterokontophyta) were collected by snorkelling during April 2010. Photosynthetic pigments were analysed by HPLC, photo-physiological parameters were estimated by PAM fluorometry and body colour was characterized by spectral reflectance. Digital photography was used to count the number and area of red spots (small red dots on the slug’s surface) on the parapodia of the 2 morphs. In the laboratory, green E. timida was fed with A. acetabulum cultured under 2 light treatments (high light, 600 µmol E m−2 s−1 and low light, 40 µmol E m−2 s−1), and digital photography was used to monitor colour alterations in E. timida. Spectral reflectance confirmed the colour differences, but both morphs showed a pigment composition similar to the green alga A. acetabulum and showed none of the pigments present in the brown alga H. filicina, neither immediately after collection of the slugs in situ, nor after the feeding experiment. A. acetabulum grown under high light intensity changed from green to brown colour and E. timida changed to brown colour when fed with high-light acclimated A. acetabulum. Thus, E. timida colour differences could not be attributed to feeding on different algae groups but was likely the result of feeding on A. acetabulum growing under different light intensities.

Pocas, pero contundentes palabras en la obra de Mendes da Rocha

La extensa producción arquitectónica de Mendes da Rocha resulta difícil de clasificar bajo el reduccionismo de los ‘ismos’ porque supone una revisión crítica y de síntesis de una modernidad replanteada. Se abordan tres aproximaciones al conjunto de su obra. Primera: la nueva tradición moderna de la arquitectura brasileña atendiendo a la implicación urbana de sus obras y a la escala de intervención (objeto, contexto, territorio). Segunda: la simbiosis entre arte y técnica desde una poética que tiende a la reducción de los elementos y a la simbolización de arquetipos. Tercera: la relativa al modo en que el maestro se enfrenta a las obras de intervención en el patrimonio recurriendo a una estética de la pobreza. Pocas, pero contundentes palabras: sencillez y humildad como atributos de la rotundidad.