Join us for a quick but beautiful journey upstream to highlight some exciting critters that play a critical role in our aquatic ecosystems!

On the bottom of streams across the Chesapeake Bay watershed live hundreds of unique species of macroinvertebrates. From mayflies to stoneflies and caddisflies, to name a few, macroinvertebrates come in all shapes and sizes. Their need for clean, well-oxygenated water makes them an excellent indicator of stream health, and their presence in streams is often monitored by our staff and partners to better understand how local streams and rivers are improving over time.

A female Ephemera guttulata (Easter Green Drake) sub imago dries its wings after hatching from its larval form

A female Ephemera guttulata (Easter Green Drake) sub imago dries its wings after hatching from its larval form. The Easter Green Drake lives two years underwater as a larva before spending a brief window as a winged adult, where it mates and lays eggs.

Spending most of their lives underwater, macros rely on a constant supply of leaf litter. Riparian forests provide this leaf input while also helping to cool the water, filter harmful chemicals or excess nutrients, and prevent sediment from covering the stream bottom. Without trees along streams, many of the macroinvertebrates in those streams would not have food or suitable habitat.

A golden stonefly larva clings to a rock on the riverbed

A golden stonefly larva clings to a rock on the riverbed. Stoneflies are one of the most pollution-sensitive macroinvertebrates found in our streams.

An abundance of macroinvertebrates often leads to thriving populations of fish and other species that prey on insects and fish. Most species of macros spend a brief but magnificent portion of their lives out of the water as adult winged insects. During these short windows, they hatch from the water in large numbers providing an important food source for many species of birds and bats.

A golden stonefly adult enjoys some sun after a morning rainstorm

Here, the adult form of the golden stonefly enjoys some sun after a morning rainstorm. Unlike the short 1-3 day adult lives of mayflies, stoneflies can live out of the water or 1-4 weeks before mating, laying eggs, and restarting the cycle.

While they might appear a little creepy, macroinvertebrates and their intricate lifecycles are a beautiful reminder of the importance of local water quality in the Chesapeake Bay watershed.

Want to learn more about macroinvertebrates? Check out two related posts OUR HIDDEN URBAN NEIGHBORS: MACROINVERTEBRATES and MACROINVERTEBRATE MENAGERIE on the Alliance blog!