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May 24, 2016
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Healthy waters, healthy fish; Biodiversity is the key

This giant stonefly was found in the Lackawaxen River. Stoneflies have between 10 and 30 stages of development (called instars), shedding their exoskeletons over a period of one to three years as they grow, before finally becoming a flying adult. Stonefly nymphs need clean cool water with lots of oxygen to survive and grow.
Photos by Faith Zerbe

Because of this diversity, the main stem of the Delaware River has the longest stretch of “Special Protection Waters” in the nation—spanning 197 miles. The Delaware River’s main stem also still flows free—making the Delaware River the largest undammed river east of the Mississippi River. This free-flowing river has sustained ancient freshwater mussels when in other parts of the country these mussels are only distant memories. One in 10 of North America’s freshwater mussel species has gone extinct and 75% of the remaining mussel species are either rare or imperiled. The Delaware River with its minimal silty bottom is home to over 14 endangered or imperiled species like the ancient dwarf wedge mussel and the eastern pearl shell mussel.

An undammed main-stem river supports spawning runs of shad and striped bass. Mussels rely on specific host fishes to support their growing young, called glochidia, as they hitch a ride and develop with help of the American eel, native brook trout, and some of the other 45 species of fish that live in the Upper Delaware River. Freshwater mussels are filter feeders that cleanse a tremendous amount of water for the benefit of us all.

If streams heat up and turn acidic from our burning of fossil fuels and clearing forests for development, which creates impermeable surfaces, increased runoff, and sediment pollution, then freshwater diversity will decline as thresholds are reached and young fish, spawning habitat and insects are smothered by sediment. If we respect the river by protecting its natural floodplain, keep and plant native landscapes, forests and meadows, we will protect ourselves and the river’s diversity at the same time. Take it from someone who was born and raised in the coal region—we want the legacy of good stewardship of our incredible natural biodiversity for the children who will come after us.

[Faith Zerbe, biologist and monitoring director for Delaware Riverkeeper Network, lives in the Lower Delaware River Valley and travels upstream to enjoy the Upper Delaware—to paddle, hike, bird watch, stream watch, snorkel, and swim whenever she has the opportunity. Follow her on Twitter @plecoptera11.]