Sunday, September 20, 2020

Some Members of Ecosystems are Becomng Younger and Shorter

Environmental & Science Education
Climate Change
Edward Hessler

A perennial complaint of anglers in Minnesota is that walleye are getting smaller. A report on walleye management from the Minnesota Department of Natural Resources notes several reasons noting finally that " The problem apparently stems from fishing pressure.

"Not only are more anglers spending more time at their sport, they also are better educated in their fishing techniques and better outfitted. This intense fishing pressure is like a mower blade, chopping off the seed and blossom and leaving the stubble - in this case the small walleye that proliferate to fill the void left by the larger fish. As the average size of the fish drops, anglers are willing to keep smaller and smaller fish, and the problem of fishing pressure is compounded.
"While our lakes produce as many pounds of fish as ever, anglers have noticed that each is catching fewer fish (because they're sharing the yield with other anglers) and that these fish are smaller."
Some wildlife specialists refer to this in evolutionary terms, i.e., "unnatural selection."
I thought of this when I read National Public Radio reporter Nathan Rott's short essay on two effects of rising temperatures, deforestation, development and climate-induced disasters on forest structure around the world.
The planet's trees are becoming younger and shorter. Forests, like the fish, just can't keep up and can no longer deal with what in the "olden days" we used to refer to as natural disasters. Now it is this double whammy of natural and unnatural disasters that is changing the components of yet other ecosystems.
I'll let you consider some of the obvious effects such as changes/loss in biological diversity, long-term storage of carbon dioxide, the possibility of recovery in the long-terms, shifts in species composition.

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