When a huge flood ripped down Wolf Point Creek in Alaska in 2005, it wiped out all of the salmon eggs, insects and all of the other creatures that lived in the stream.
The water had acted like a huge flush, stripping all life from the stream.
Scientists who had been studying the creek for 28 years had all kinds of information about what lived in the water before the flood. So afterward, they could watch as life slowly returned to the stream.
Their work provided a unique insight into how nature heals itself.
Pink salmon returned to the creek two years after the flood, but in very low numbers — less than 500.
Four years later, their numbers had returned to what they were before the flood — more than 15,000.
Insects that live in the water, called macroinvertebrates because they have no spine and can be seen with your naked eye, returned but were much different. Beetles, freshwater shrimp and caddisflies had not returned three years after the flood. But midge larvae, which had trouble competing with the other insects, returned. Overall, there were just as many bugs, but different kinds, the researchers found.
Small animals immediately moved in after the flood because the high water had removed much of the sediment — the fine soil and sands on the bottom of the stream — leaving spaces for the animals between the stream bottom’s rocks.
“We were really surprised by our findings,” said Sandy Milner, one of the researchers. “They illustrate the rapidity with which pink salmon populations are able to recover, and demonstrates their resilience to high-magnitude flow disturbances.”
— Brett French,
Gazette Outdoors editor