A tropical forest is cleared for oil-palm plantations, leaving only small patches for resident primates. Which major threat to biodiversity does this represent?

Fishers remove breeding-sized groupers from a reef faster than the population can replace them. Which biodiversity threat is occurring?

A nonnative crayfish released from an aquarium spreads through a stream and displaces native crayfish from shelter. What threat does this case represent?

After fertilizer runoff enters a lake, an algal bloom is followed by low dissolved oxygen and a fish kill. Which major threat is the initial human-caused driver?

Repeated unusually warm ocean temperatures cause corals to bleach across a reef. Which direct threat is most clearly represented?

A new highway cuts a grassland into two sections, and pronghorn can no longer move between feeding and breeding areas. What threat is illustrated?

Collectors remove large numbers of wild orchids from a small mountain population for sale. Which threat is acting directly on the population?

Ballast water discharged from cargo ships introduces zebra mussels to a lake, where they alter food webs and crowd native mussels. What threat does this describe?

Acidic drainage from a mine enters a stream and sensitive aquatic insects disappear downstream. Which biodiversity threat is the mine creating?

A coastal mangrove forest is removed to build shrimp ponds, eliminating nursery habitat for juvenile fish. Which threat is most direct?

Earlier snowmelt and hotter summers dry alpine ponds before salamander larvae complete development. Which threat is best identified?

Domestic cats introduced to an island prey on ground-nesting native birds that evolved without mammalian predators. Which threat is represented?

Read the chart. Which direct driver has the greatest relative impact on recent terrestrial and freshwater species-status declines?

In the oceans, which direct driver has the largest relative impact on biodiversity according to the IPBES global assessment?

A conservation plan must prioritize broad global drivers of terrestrial species loss. Which threat should generally be ranked first?

Which comparison between major direct drivers is accurate?

Read the chart from a coastal survey. Which threat should managers rank as the largest immediate source of population decline?

Read the chart. Which threat has the smallest measured contribution in this watershed survey?

A county will build a subdivision through a continuous forest and also remove a few deer through regulated hunting. Which threat is likely to dominate the forest-wide biodiversity impact?

Read the table. Which pressure should receive first priority if managers address the threat affecting the greatest number of declining species?

A dam prevents migratory fish from reaching upstream spawning gravel. What is the most likely population effect?

A road isolates two populations of a rare wildflower, and pollinators rarely move pollen between them. Over generations, what is most likely?

A bleaching event kills much of a coral reef's three-dimensional structure used by juvenile fish for shelter. What is the most likely result?

A gill-net fishery accidentally entangles adult sea turtles while targeting fish. How can this bycatch affect the turtle population?

Nitrate runoff triggers an algal bloom. Decomposers then consume dissolved oxygen as the algae die. What happens to oxygen-sensitive fish?

A nonnative grass spreads rapidly after a fire and uses water needed by native seedlings. What is the most likely effect on the native seedlings?

Herbicide drift removes nearly all native flowering plants from a field margin used by local bees. What change is most likely in the bee community?

Warming reduces the duration of sea ice used by seals as a platform for giving birth and nursing pups. What population effect is most likely?

A fishery removes many predatory fish from a kelp forest food web. The predators normally eat herbivorous fish that consume kelp. What change is most likely?

Forest clearing creates more edge habitat, where nest predators and brood parasites are more common. What is a likely effect on an interior-nesting bird?

An amphibian population is already confined to one small pond when a fungal disease arrives. Why is this combination especially harmful?

Warming shifts a mountain species' suitable climate upslope, while development blocks movement to higher habitat. Why does extinction risk increase?

A depleted fish stock experiences continued harvest while a heat wave reduces larval survival. What is the most likely result?

Forest fragments create sunny edges, and a nonnative vine spreads along those edges and smothers native seedlings. How do the threats interact?

An island bird loses forest nesting sites while introduced rats consume its eggs. Why can its population decline rapidly?

A wetland is drained into a few small ponds, and hotter summers cause the remaining ponds to dry earlier. What is the likely outcome for a pond-breeding frog?

A road divides a deer population and vehicle collisions occur where deer attempt to cross. What is a likely benefit of a wildlife crossing linked to habitat on both sides?

An estuary loses seagrass after nutrient-driven turbidity blocks light, while a nonnative crab consumes juvenile fish. Why may fish diversity fall faster than from either threat alone?

An endemic plant occurs only on one mountain slope. Mining removes part of that slope while climate warming shifts suitable conditions upward. Why is the plant especially vulnerable?

A small isolated wolf population faces illegal killing and has little gene flow with other packs. Why is the combination more serious than illegal killing alone?