Question

formerly absent. sampling revealed no movement into salt creek, but numbers of bull trout in the elwha river estuary increased greatly during and immediately after dam removal, coinciding with large sediment outflow, before returning to their original low levels. thus, bull trout appear to have used the enlarged estuary as a refuge from the effects of dam removal, then returning to the river when the river water cleared up from the sediment. of additional interest is the long - term response of bull trout to the additional habitat opened up above the former dams. lincoln, a. e., j. a. shaffer, and t. p. quinn. 2018. opportunistic use of estuarine habitat by juvenile bull trout, salvelinus confluentus, from the elwha river before, during, and after dam removal. environmental biology of fishes 101:1559 - 1569 which of the following best identifies the author’s claim? a bull trout experienced high mortality rates as a result of the formation of the estuary and sediments released during dam deconstruction. b bull trout are adaptable to a variety of habitats and were able to survive in the river habitat during the dam deconstruction. c bull trout remained in the estuary system after the dam deconstruction because the disruption had irreversibly altered the river habitat. d bull trout are unable to live in high sediment loaded waters and migrated to avoid the conditions introduced during dam deconstruction.

Explanation:

The text states that bull trout numbers increased in the estuary during dam removal (with large sediment outflow) and then returned to the river when the water cleared. This implies they couldn't live in high - sediment water (used estuary as a refuge) and migrated back when conditions improved.

• Option A: The text says numbers increased in the estuary during dam removal, not high mortality.
• Option B: They used the estuary (not the river during dam deconstruction as a main habitat).
• Option C: They returned to the river, so the river habitat was not irreversibly altered.
• Option D: Aligns with the text's description of using estuary (avoiding high - sediment river water) and returning when sediment cleared.

Answer:

D. Bull trout are unable to live in high sediment loaded waters and migrated to avoid the conditions introduced during dam deconstruction.