Spatial and temporal variation of natural toxicity in cnidarians, bryozoans and tunicates in Mediterranean caves

The natural toxicity of cnidarians, bryozoans and tunicates in two caves was assessed using the Microtox® technique in spring and autumn. One cave was located in the Cabrera Archipelago (Balearic Islands) and the other in the Medes Islands (Catalan littoral). The organisms analysed were good representatives of the coverage of each Phylum in the communities; however, these Phyla are less abundant than sponges which are the dominant group in these caves. Seventy-one percent of the species of cnidarians and bryozoans analysed were toxic in one of the caves, communities or seasons, which indicates the relevance of bioactive species in these groups. The tunicate Lissoclinum perforatum was the most toxic species. Although all three Phyla had some highly toxic species, a common pattern that related the caves, communities and seasons was not found. Seasonal variation of toxicity in cnidarians and bryozoans was higher in the Cabrera than in the Medes cave. Moreover, variation in toxicity either between communities or between seasons was a common trait for most cnidarians and bryozoans, whereas tunicates remained toxic throughout communities and seasons.

A general approach to the in situ energy butget of Eudendrium racemosum (Cnidaria, Hydrozoa) in the Western Mediterranean

An in situ energy budget of the hydropolyp Eudendrium racemosum (Cavolini, 1785) is presented. Ingestion and respiration rates and ammonium excretion were studied over two 24 h cycles, with two-hour sample intervals. The species ingested as much as 25.9% of its own biomass per day (minimum rate). Respiration was 1.62 ml O2 g-1 d w h-1 while excretion was 13.6 mM NH4 g-1dw h-1. We estimated that the species increased its biomass at a rate of 9.6% per day (Growth + Reproduction). This value is higher than those previously reported for other cnidarians. We can assume that the capacity of E. racemosum to survive - albeit for a limited period of the year - in the highly-competitive shallow-water communities is based on its high growth rate.

Seguiment temporal de la gorgonia Paramuricea clavata de les Illes Medes. Exercici 1995

Podeu consultar l'Informe complet a: http://hdl.handle.net/2445/24663

Seguiment temporal de la gorgònia Paramuricea clavata de les Illes Medes. Exercici 1999

Podeu consultar l'Informe complet a: http://hdl.handle.net/2445/23667

Seguiment temporal de la gorgònia Paramuricea Clavata de les Illes Medes. Exercici 2000

Podeu consultar l'Informe complet a: http://hdl.handle.net/2445/23669

Seguiment temporal de la gorgònia Paramuricea Clavata de les Illes Medes. Exercici 2001

Podeu consultar l'Informe complet a: http://hdl.handle.net/2445/23672

Seguiment temporal de la gorgonia Paramuricea Clavata de les Illes Medes. Exercici 2002

Podeu consultar l'Informe complet a: http://hdl.handle.net/2445/23675

Seguiment temporal de la gorgònia vermella (Paramuricea clavata) de les Illes Medes. Exercici 2003

Podeu consultar l'Informe complet a: http://hdl.handle.net/2445/23677

La gorgònia Paramuricea Clavata

Podeu consultar l'Informe complet a: http://hdl.handle.net/2445/23686

Invasions gelatinoses

Fa anys, durant la meva adolescència, vaig ser un devorador voraç de llibres de ciència-ficció, i no només de ciència-ficció. En un d'aquests llibres, titulat La legió de l'espai (1934), Jack Williamson descriu la invasió de la Terra per uns éssers monstruosos procedents d'un arcaic planeta, als quals anomena els meduses per llur semblança amb els seus homònims terrestres: "John Star [el protagonista] va captar la semblança superficial, la configuració en forma de volta, l'orla de tentacles que els havia fet merèixer el nom de meduses. Vistos de lluny no resultaven imponents. No semblaven intel·ligents [...].