Creek Creatures

The temperatures may be well below freezing, but as long as the water remains ice free, I can enjoy watching aquatic creatures going about their business on the bottom of the creek.  On this sunny day, Caddisflies were busy dragging their stone casings around as they grazed algae and other morsels from the rocky stream bottom.

If I’m going to observe aquatic animals in the creek, it’s got to be done in the winter and spring.  Lack of water in the summer and fall makes it difficult to find those animals that maintain an aquatic existence.  During the wet phase, the creek is full of easily observed life.  I assume that these species are adapted to life in an environment that annually cycles between wet and dry.

Caddisflies use sand to adorn the silken sack in which they spend their larval stage.  This camouflage allows them to blend quite well into the rocky creek bottom.

Patterning of the mayfly larvae makes them hard to notice as they move across the substrate.  Their shape resists the drag of the passing water and allows them to avoid being easily swept downstream.

The creek supports several species of snails.  Snails spend the dry season beneath stones or buried in the gravel stream bottom.

Snails feed on algae scraped from the rocks.  Consumed material moves quickly through the snail’s gut and is expelled as nutrient rich pellets.  This process converts the energy of the algae into a form usable by many other organisms.  Without animals like the snail, there would be no fuel to sustain the animal life of the stream.

There were a lot of tiny creatures that I wasn’t able to identify.  I imagine that they will become more recognizable as they grow.  Temperature was at 23 degrees and wind was about 15 mph so I didn’t remove any of these animals from the water.  I didn’t think exposure to that cold air would do them any good and I didn’t want to freeze my fingers in the process of capturing and examining the little guys.

Isopods were a childhood favorite of mine.  I was intensely interested in paleontology and in my mind the aquatic isopod was as close as I could get to a living trilobite.  I used to keep a few in a jar on my dresser and spent hours watching them.  Watching these scavengers forage across the rock face reminded me of those days spent observing my captive specimens.

These animals spend most of their time hidden beneath the rocks.  It was interesting to see them out going about their normal business in the bright sunlight.

Planaria have always survived in the smaller tributaries, but it was just a few years ago that I first saw them in the main creek that passes through Blue Jay Barrens.  Planaria need clean, well oxygenated water and disappear quickly if water quality deteriorates.  Concentrations of cattle in the watershed above Blue Jay Barrens used to add a high nutrient load to the water, causing rapid growth of algae in the creek.  The cattle have gone and the water quality is more typical of a natural stream.  This has allowed the planaria to successfully move from the tributaries to the main creek.

Water Garden Mud Flat

I’ve never doubted the wisdom of putting a water garden outside the front door to my house. It has been a constant source of entertainment and educational opportunities.

Each summer the water garden displays a phenomenon that I have come to call the artificial mud flat. The bottom of the water garden is a plastic liner that leaves little to which aquatic plant roots can anchor. The water lilies were originally planted in containers that gave plenty of room for root growth. The roots have long since left those containers and now sprawl far from the pots. Eventually, they reach a point where their buoyancy brings them to the surface along with a healthy load of bottom detritus. Once it surfaces, the mat is quickly consumed by tadpoles and the roots once more head for the bottom. While it exists, tiny flies track the surface like flocks of shorebirds. The whole sequence is quite interesting, even though it’s not something you can plan for.

The water lily leaves got blasted by two hail storms. The leaves now bear scars of the encounter. Most plants didn’t suffer at all from the hail. The floating leaves were perfectly positioned to allow penetration by the hail stones.

Male mayflies have been swarming above the water garden. They adopt a bouncing flight pattern designed to attract females. The long front legs are used to capture and hold the female during mating.

The bulrush is looking like a set of glow tubes as it catches the setting sun. The idea of having tall plants to the back of the water garden and short plants in front worked fine until the plants produced seed and developed their own arrangement.

A Little Bend in the Creek

When I have the time, I like to spend a few minutes in one loction to see what I can find. I decided to spend a little time at this spot in the creek before the flow completely stops. A nice gravel bar has developed on the inside of the curve where the creek takes a turn to the left.

The force of water during high flow conditions is expended against this limestone bedrock on the right bank. The bedrock layers have a definite lean to the left as a result of the meteor strike 300 million years ago. You can get a good idea of the shallowness of the soil over this rock. The exposed roots of the dead cedar stump show how they are stopped by the impenetrable limestone.

Here’s the source of the Field Horsetails that are now circling my water garden and charging out across the driveway.

The water flow has really slowed in this small pool. It won’t be too long before the water stops moving all together. Small pools like this are often dry by early September.

There are several aquatic creatures living here. The easiest way to find the swimming and floating animals is to watch for their shadows on the creek bottom. Water Striders are present everywhere there is enough water on which to float. The shadow shows the size of the dimples made by the Water Strider’s feet pushing down on the surface of the water. Small fish are also present. These are probably young Northern Creek Chubs. The mature chubs make their way up the creek to breed during high water in spring. You can see one fish just below the Water Strider and one a little ways to the left.

Some of the Streamside Salamander larvae are still in the creek. The little fish are large enough to cause problems for these larvae. The salamander is big enough to eat the fish if it could catch them, but if given the chance, the fish will feed on the salamander’s gills and any other little parts they can get hold of.

I picked up a 3 inch flat rock and found some interesting life beneath.

This is a hellgrammite, the larva of the Fishfly.

Here's the larva of a Dusky Salamander. It will spend its entire life beneath rocks in or near the creek.

I didn’t notice this mayfly larva when I took the picture. I was checking the picture of the hellgrammite and salamander larva when I spotted the image of the 3 tail filaments common to mayfly larvae. You can see the tail on the left in this picture and you can see the eye spot on the right. This particular species is shaped to resist the water currents as it clamors around on the rocks grazing algae.