Scott Shalaway: Getting to Know Aquatic Life
In just a few weeks temperatures will get uncomfortably warm. A great source of thermal relief is a spring-fed stream where one can wallow on a hot summer day. Such days are great opportunities to study aquatic life.
With just a facemask, a snorkel, and an old pair of sneakers, you can observe aquatic life on its own terms — underwater. Snorkeling opens a whole new world for curious naturalists.
Though many people associate snorkeling with coral reefs or tropical lagoons, cold, rural streams offer great local snorkeling opportunities closer to home.
Regardless of where you snorkel, however, make safety your primary concern. Never snorkel alone. Stay in shallow water. And never explore under large rocks or submerged logs.
Before getting wet, walk a length of stream, and notice it consists of two parts: slow moving pools and rapidly flowing riffles.
Pools may be as small as a birdbath or as large as a swimming pool. When I find an inviting, knee-deep pool, I put on my mask and snorkel, float face down, and watch. Within a few minutes, curious fish approach. Invest 15 minutes, and you’ll probably see at least a few sunfish.
In bigger, darker pools, scan under a tangle of roots or under floating logs. These dark refuges provide excellent cover where larger predatory fish such as trout and bass await passing prey — insects, smaller fish, frogs, snakes.
Even more interesting are the smaller fish found in the shallow, rapidly flowing riffles. This is the noisy, “gurgling” part of the stream. Here, where the flow rate is often so fast it seems every living thing should be swept away, is where the darters live.
Facing upstream, lie down in a riffle to view the darters. Inch into the current and scan the rubble. Notice the small fish darting among the stones.
Darters are suited to life in swift currents. Some position themselves on the upstream side of larger rocks where the current is significantly slower. Others wedge themselves between the stones on a tripod consisting of the tail and pelvic fins. Still others bury all but their heads in fine sand or gravel.
Masters of disguise, darters can be drab and difficult to see. Some, though, display almost gaudy patterns of reds, blues, and oranges. Brightly colored darters are the warblers of the fish world.
But it’s not necessary to get wet to observe aquatic life. On the water’s surface you’ll find predaceous water striders and frantically active whirligig beetles searching, hunting for prey. Where the water is clear, you may see crayfish patrolling the streambed.
But most freshwater invertebrates stay hidden beneath large flat rocks that cover clear stream bottoms. Gravel stream bottoms are home to many species of freshwater clams, mussels, snails and larval aquatic insects. Flip large flat rocks, let the current clear the sediment, and you’ll observe an impressive diversity of aquatic life.
The flat-bodied creatures that cling tenaciously to the undersides of submerged rocks are stonefly and mayfly larvae. From the tip of the abdomen of stonefly larvae, you’ll notice two tail-like filaments. Larval mayflies have three such tails. The presence of stoneflies and mayflies indicate clean water that should hold catchable fish.
My favorite aquatic insects are caddisfly larvae. If you notice a bundle of tiny pebbles or twigs moving across the stream bottom, watch it closely. Pick one up, and you’ll discover it’s home to an insect. On one end there’s a head and thorax, complete with legs. The soft tissues of the abdomen are protected by the case that surrounds it.
Caddisfly larvae build their own house and carry it on their back. The weight of the case helps anchor the larvae in moving water, and it’s excellent camouflage when the larvae rests. The materials used to make such cases include grains of sand, tiny pebbles, and sometimes plant material. Some of the pebble-users actually build a spiral case that can easily pass for a snail.
No one hates hot, steamy weather more than I, but it presents a great opportunity to get wet, stay cool, and learn a little natural history.
Dr. Scott Shalaway can be heard 8 to 10 a.m. Saturdays on 1370 WVLY-AM (Wheeling) or online at www.watchdognetwork.com. Visit Scott’s web site www.drshalaway.com or contact him directly at firstname.lastname@example.org or 2222 Fish Ridge Road, Cameron, WV 26033.