Question

Bioindicator species show:

1) presence of specific conditions in the environment
2) presence of pollutants in the environment
3) presence of excessive nutrients in the environment
4) general quality of the environment
5) all of the above

Answer 1

Bioindicator species can reveal the presence of excessive nutrients in an environment, potentially leading to eutrophication, hypoxia, and biomagnification of harmful substances like PCBs and heavy metals in food chains.

Step-by-step explanation:

Bioindicator species can show the presence of excessive nutrients in an environment, leading to phenomena such as eutrophication and hypoxia. Substances like polychlorinated biphenyls (PCBs), and heavy metals such as mercury, lead, and cadmium are known to biomagnify in aquatic ecosystems.

For instance, a NOAA study demonstrated that PCB concentrations in Saginaw Bay of Lake Huron increased at each trophic level, with apex predators like walleye containing significantly higher PCB levels than phytoplankton. Similarly, nutrient-rich conditions, often a result of human activities like agriculture and urban runoff, create an environment susceptible to algal blooms and subsequent dead zones, as observed in nearly 50% of lakes in North America, Europe, and Asia, and in the large dead zone offshore Louisiana in the Gulf of Mexico.