Essay on The Effect of Herbivory on Plants

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Intense grazing by herbivores can drastically affect the amount of seaweed present. Having secondary metabolites can be used as a defence mechanism. Many different genres of algae were studied, having many different types of chemical compounds found on many different parts of the world. Most studies harvested and purified samples then exposed these samples to different herbivores. The herbivores varied in size from large fish to smaller organisms such as amphipods. Aspects such as survivorship, behaviour and chemical composition were analyzed. All the studies have shown that there was an avoidance and low survivorship when herbivores were feed these samples. There also seems to be variation in chemical composition and palatability…show more content…
It is now known that Secondary metabolites are used commonly in a defence against herbivores, pathogens, fouling as well as giving competitive advantages and act as a gamete attractant. (Hay 1996) This is how plants and more specifically, seaweeds minimize the damage done by herbivores. Studies involving secondary metabolites have been recognized extensively in terrestrial habitats. (Paul & Fenical 1986, Bennet & Wallsgrove 1994) It is known to play an important evolutionary role in determining plant susceptibility to herbivore grazing. (Hay et al 1988) Investigating marine habitats where this phenomenon takes place is lesser known in comparison to terrestrial habitats. Many comparisons are made due to the fact that mesograzers are ecologically similar in mobility and size to insects. Secondary Metabolites seen in Tropical Zones One example seen of secondary metabolites is seen in a study done on order Caulerpales. Caulerpales algae are located in more tropical areas of the world, and are known to be a low preference of food in the diets of macroherbivores, as well as microherbivores. The most common toxic chemical found in this order is in the terpenoid family. In this particular study 40 species from this order was collected throughout the Bahamas, Florida Keys and in Puerto Rico. (Paul & Fenical 1986) Once collected, algae was ground and extracted with dichloromethane. Chlorophyll was removed from these extracts then frozen for
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