 key ideas prerequisites and misconceptions before you start key ideas introduced in this unit  mercury bioaccumulates mercury amounts in organisms increase at higher trophic levels mercury is toxic to humans and other organisms dragonflies are a key part of the aquatic food web and are exposed to mercury concepts and relationship  mercury can enter organisms in several ways mercury stays in the body for a long time mercury primarily affects the brain nervous system and kidneys a fetus that is exposed to mercury can be born with severe nerve and or kidney damage as well as developmental disabilities a study site contains a lot of components that might all have mercury soil water organisms plants etc get acquainted with you field site and start thinking about how it may be affected by mercury  vocabulary  bioaccumulation the collection of higher and higher concentrations of potentially toxic chemicals in individual organisms it occurs in the case of chemicals that are ingested but cannot be broken down or excreted biomagnification bioaccumulation occurring through several levels of a food chain food chain a set of organisms that feed one upon another linearly and thus pass energy along the chain an herbivore eats a plant the herbivore is eaten by a carnivore which is then eaten by another carnivore food web multiple interconnected food chains some animals eat and are eaten by many other types of organisms in a complex web life history the sequence and timing of events in an organism s life cycle for example some life history traits include how long an organism spends as a larva what it eats and when it is ready to reproduce macroinvertebrate an organism without a backbone that is large enough to be seen without a microscope mercury cycle the deposition and uptake of mercury from the emission source to the ingestion by organisms methylmercury the byproduct of metabolism by anaerobic bacteria typically living in an acidic environment with access to carbon and sulfur study organism the organism that is the subject of a research project toxicity the degree to which something is poisonous trophic level as organisms eat other organisms all the substances they contain are passed up the food chain or up tropic levels producers green plants and algae primary consumers herbivores secondary consumers carnivores student prerequisites  how to measure volume and square inches how to convert units such as g g to ppb or ppm see activity a in unit 1 proportions averages ranges computer skills library skills misconceptions about mercury  mercury is not a problem in maine quantities of mercury that we ingest are not sufficient to cause harm there is nothing interesting to study at my site  mercury in watersheds  