Induction de défense contre l'herbivore Littorina littorea dans l'algue Fucus vesiculosus : influence des stimuli et variation géographique

Melançon-Bourgeois, Simon (2010). Induction de défense contre l'herbivore Littorina littorea dans l'algue Fucus vesiculosus : influence des stimuli et variation géographique. Mémoire. Rimouski, Québec, Université du Québec à Rimouski, Institutdes sciences de la mer de Rimouski, 81 p.

Prévisualisation

PDF Télécharger (3MB)

Résumé

Induced defense against the herbivore Littorina littorea in the seaweed Fucus
vesiculosus: influence of stimuli and geographic variation

Grazing by marine herbivores can heavily impact macroalgae, which, in turn, reduce
biomass losses through induced resistances. Although this topic has been much studied in
recent years, there exists no information on this defense mechanism in the subarctic
northwest Atlantic. We tested the macroalga Fucus vesiculosus for inducible resistances by
various cues and for plasticity in the response to different grazing pressures. In laboratory,
we exposed seaweeds to artificial wounding (clipping) and to two densities of the gastropod
Littorina littorea. We assessed whether algae had a decreased palatability every third day
for a period of 21 days. Defense was established upon a greater feeding rate of periwinkles
on ungrazed/unclipped (control) seaweeds vs. previously manipulated seaweeds in
subsequent choice feeding assays. Grazing by the two periwinkle densities caused a trend
of resistance of similar intensity while artificial wounding significantly induced defense in
seaweeds for 6 consecutive days. While we did not demonstrate a correlation of
phlorotannin concentrations with the trend of decreased palatability nor defense flexibility
for the two grazing magnitudes, an inducible resistance in a macroalga is established for the
first time in the subarctic northwest Atlantic. The few evidences where L. littorea grazing
does not trigger a reduced palatability in F. vesiculosus from the northwest Atlantic hint for
a geographic variation with the Baltic Sea where it do es stimulate a resistance.

Type de document :	Thèse ou mémoire de l'UQAR (Mémoire)
Directeur(trice) de mémoire/thèse :	Archambault, Philippe
Information complémentaire :	Mémoire présenté à l'Université du Québec à Rimouski comme exigence partielle du programme de maîtrise en océanographie. Publié aussi en version papier.
Mots-clés :	Algue Fucus Vesiculosus Induction Mecanisme Defense Herbivore Broutage Littorina Littorea
Départements et unités départementales :	Institut des sciences de la mer de Rimouski (ISMER) > Océanographie
Déposé par :	DIUQAR UQAR
Date de dépôt :	22 sept. 2011 13:33
Dernière modification :	22 sept. 2011 13:34
URI :	https://semaphore.uqar.ca/id/eprint/421

Actions (administrateurs uniquement)

Éditer la notice