Teacher’s Guide to Questions: Intermediate Grades 
General (Based on Grade 7 Understanding Life Systems): Answers

• Riverwood bans chemical sprays to control pests. How does this affect the ecosystem? Chemicals which in the past would have entered the ecosystem through the water system and the soil are no longer present. This promotes a healthier ecosystem but it also leaves plants and animals more vulnerable to infestations by organisms that prey on them. It also means that invasive species, like garlic mustard, must be controlled by labour intensive human effort such as pulling out the plants.
• If the ban were lifted, how would it change the ecosystem? Invasive species would be better controlled. Garden plants would be healthier and would our lawns. Insect populations would decline, large fish (salmon) would contain more pollutants, bird populations would be reduced and that is just for starters. 
• Riverwood is surrounded by urban development. How does this impact the areas’ ecosystem? Human activity has directly brought in at least five of the most invasive species; garlic mustard, starlings, giant hogweed, phragmites and purple loosestrife. Noise and air pollution from traffic affect birds. Domestic dogs and cats compete with native predators. A warming climate due in part to human activities has changes plant and wildlife distribution. Non-native Chinook salmon and rainbow trout have been introduced into the river. Forests have been cleared for homes. The water table has declined. Species such as black bear have been extirpated.  On the positive side, humans created Riverwood and have stewarded the land to restore it to something approaching its former biodiversity.
• How would climate change effect the species featured?  Climate change has led to an expansion in the range of some species found at Riverwood (cottontail rabbit, opossum). Promoted better conditions for some invasive species to live and thrive (garlic mustard, Nile virus). Likely led to the decline of some native trees like the ash trees because the warming climate supported the spread of the invasive Emerald ash borer insect. It has also created conditions where weather events tend to be more severe in than in the past which has caused strong wind gusts to blow down trees more frequently.
• If it was important to restore black bears to Riverwood, what steps would have to be taken to ensure the species could survive here? To establish a breeding population if black bears in the Credit River watershed (which includes Riverwood) large tracts of forested land would have to be re-established. These tracts of land would need to be connected by wildlife corridors that linked them. A major change in human attitudes towards large predators would need to occur as well as a management plan that would ensure the safety of humans and their pets. Would this be a good species to try and bring back? No. However the Greater Riverwood Ecosystem is not large enough to support a viable breeding population. The lack of enough natural foods in the local environment would lead to bear-human conflict as the animals invaded gardens and garbage bins for food. Why? Black bears can be an indicator species of a healthy ecosystem.  Why not? However the Greater Riverwood Ecosystem is not large enough to support a viable breeding population. The lack of enough natural foods in the local environment would lead to bear-human conflict as the animals invaded gardens and garbage bins for food.
• What is the top predator found in Riverwood (it is featured in the videos)? Coyote
• List the biotic elements seen in the videos. Plants, animals
• List the abiotic elements seen in the videos. Water, air, soil, rocks, mud
• Which producers are featured in the video? Any of the plants seen in the video would be on the list.
• Which consumers are featured in the videos?  All animals are consumers.
• Which species are predators as well as prey for larger predators? Some examples: Toads prey on insects, snakes prey on toads. Raccoons prey on bird’s eggs and insects, coyotes prey on young raccoons.
• Which species compete with other species for resources? Some examples: Birds at a feeder compete for the sunflower seeds. Deer compete with Canada geese for grains.
• Which species are at the top of the food chain? Gray wolf, Coyote, Black bear, Red-tailed Hawk
• Which species are at the bottom of the food chain? Generally the smaller the species the lower it is on the food chain.
• Describe the transfer of energy up the food chain based on the species seen in the videos. Simple Food Chain (3 links):Plant (producer) > Deer (consumer/herbivore) > Coyote (consumer/carnivore).Complex Food Chain (many links): Water plant (producer) > Insect (consumer) > Green frog  (consumer) > Green Heron (consumer) > Fox (consumer) > Coyote (consumer)
• What would happen if one of these links in the food chain disappeared? The food chain would change and some species may decline or even disappear.
• Human intervention has restored two species to Riverwood and the Credit River; the wild turkey and the Atlantic salmon. How successful have these restorations been? What factors have limited their success? Neither has been that successful to date. Lack of habitat and the presence of coyotes, raccoons and human pets have all probably been factors that limited wild turkey’s nesting success. Outside the GTA the turkey reintroduction was very successful. The Atlantic salmon has only been partially successful due to the presence of Alewife (a small fish) that arrived in Lake Ontario in the 1800’s after the building the Erie Canal. When Atlantic salmon eat this fish their breeding systems are disrupted and females cannot lay fertile eggs. 
• Human intervention introduced the Chinook salmon into the Credit River. What are the pros and cons of this introduction? Pros: Helped develop a viable sport fishing industry on the Credit River and in Lake Ontario. Added a new food source to the watershed. Cons: The species is non-native and competes with other fish in the watershed.

 
 
 General (Based on Grade 8 Understanding Earth and Space Systems): Answers

• Which species rely on water for their survival?  ALL
• Which species nest in wetlands? Red-necked Grebe, Canada Goose, Mallard duck, Green Heron, Great Blue Heron, Cormorant, Alligator, Muskrat
• Which species breed in wetlands? Frogs, Toads, Fish, Waterfowl, Red-wing Blackbird, Turtles, Beaver, Muskrat, Mink, Otter, Alligator
• How does the changing availability of water effect the ecosystem? (I.e. Droughts, Floods, Seasonal Changes, Climate Change) A lack of water (drought) can lead to loss of plant life and the wildlife that relies of in. Flooding can have a similar impact by drowning plant life or tearing it down with a loss of wildlife. Seasonal changes are part of the rhythm of nature and wildlife has the ability to adapt to it. The degree to which they can adapt however varies from species to species. Ethologists (scientists who study animal behaviour) speak in terms of how plastic a species response to change is. (Plastic refers to a species ability to change. Deer are quite adaptable and very plastic in their response. Spring peepers (extirpated from Riverwood in the last two decades) are very ridge and could not adapt to changes. They are not very plastic in their response. Evolutionary biologists also use the term genetic plasticity to describe this ability to respond to change. However major climate shifts or abrupt changes in weather patterns can stress the wildlife (plants and animals) to the point where they are negatively affected. Chinook salmon wait to migrate up their natal streams until a heavy rain raises the level of the river and washes the river’s scent into Lake Ontario.
• How might human activities effect the water sources species need for their survival (give both positive and negative examples)? Negative: human caused pollution can negatively stress the environment and lower water quality. Dams can increase deposition in some places, lower water level in others and cause a loss of nutrients downstream from the dam. Dams also alter the natural rhythm of the river by reducing seasonal flooding. Seasonal flooding can remove debris, carry nutrients into the water and improve the overall health of the river. Dam building on the Credit River in the 1800’s was a major factor in the extirpation of the native salmon (Atlantic salmon). Positive: Planting trees along the shore to stabilize the banks and reduce erosion and sediment. The trees also provide shade which cools the river/water for cold-water loving fish like salmon. Reducing chemical treatments for lawns and gardens reduce the pollutants that reach the water. Cleaning up spills and other events that impact the water. Passing and enforcing regulation that help improve the environment.