Herbivore-like damage induces increased strength and toughness in a seaweed

Abstract

The seaweed Ascophyllum nodosum responds to simulated herbivore damage with an induced increase in tensile strength and toughness (force and work required for breakage), demonstrating a capability in plants for an induced response that reduces the probability of breakage. These properties are especially valuable because Ascophyllum is prone to losing much more tissue indirectly owing to herbivore-caused breakage than directly as a result of consumption by herbivores. Furthermore, the amount of past damage to Ascophyllum fronds is an indication of the probability of future damage, favouring an induced response in particular. In contrast, this damage induces a decrease in potential chemical feeding deterrents and an increase in edibility. Plant responses to herbivory appear to be complex and may reflect trade-offs between the costs of different kinds of responses.