Ecología química en el bentos marino de la Antártida: productos naturales y defensa química en esponjas hexactinélidas, corales blandos y ascidias coloniales

• Main Author: Núñez Pons, Laura
• Other Authors: Ávila Escartín, Conxita, Maldonado Barahona, Manuel, Universitat de Barcelona. Departament de Biologia Animal
• Format: Doctoral or Postdoctoral Thesis
• Language: Spanish
• Published: Universitat de Barcelona 2012
• Subjects: Ecologia marina; Ecología marina; Marine ecology; Defensa química; Chemical defense; Productes naturals; Productos naturales; Natural products; Antàrtida; Regiones antárticas; Antarctica; Invertebrats bentònics; Invertebrados bentónicos; Benthic invertebrates; Ciències Experimentals i Matemàtiques; 59; Antarctic; The Antarctic; Antarc*; Antártida
• Online Access: http://hdl.handle.net/10803/104105

The inhabitants of marine benthos must combat the ecological pressure caused by predation, competition and fouling through a series of mechanisms, one of which is chemical defense. This type of protection is particularly extended among sessile and/or sluggish organisms, such as sponges, soft corals or ascidians. The strategies to prevent predation are related to bad taste rather than to toxicity. Moreover, they must be considered along with nutritional quality, since the more nutritious the prey, higher quantities or more potent repellents are needed to gain protection. The production of defensive secondary metabolites is energetically expensive. For this reason, the Optimal Defense Theory (ODT) predicts that defenses must be allocated in the most valuable or more exposed structures or body-regions. In Antarctic communities, the main predators are asteroids, and defensive agents are hence expected to accumulate in superficial layers of potential prey. But dense populations of amphipods, which associate opportunistically with biosubtrata, obtaining both refuge and direct or indirect sources of nutrition, are also very influencing on these bottoms. It has been reported that chemical defenses are very common in Antarctic organisms, in accordance with our results. However, the research effort has not been the same for all the groups, and there are still many aspects to learn on the chemical ecology, like the identification of the implicated products, their mode of functioning or their localization and origin. This PhD has focused on three relevant groups of the Antarctic benthos, quite understudied: hexactinellid sponges, soft corals and colonial ascidians. Two influencing sympatric predators were selected, the sea star Odontaster validus, which is a known model predator, and for the first time, the amphipod Cheirimedon femoratus, used to perform feeding experiments for the detection of repellent chemical defenses. We designed a new protocol which provided numerous methodological profits, as well as a remarkable ...