Monday, September 10, 2012

Under The Susquehanna

We are drawn riverward as we explore the riparian habitat along the river here in Pennsylvania's scenic mountains.  Since we have our water shoes on, we'll wade out - and even dive - into this vast and enrapturing underwater world.

In water, under the swirling currents, there is a realm of aquatic life that we love to explore. 
Yes, it's a wonderful world - this water world - as it wends its way along from headwaters to the ocean.  Between the mountain streams and the bay there are may changes along the way.
   The West Branch Susquehanna River, right here at this location, seems almost devoid of life.  At least at first glance.  Actually, there is an abundance of a relatively few creatures (low biodiversity).  This is a result of a combination of physical and abiotic factors, such as acidity... and of course the tolerances of the aquatic creatures.
  Two of those abundant creatures are the aquatic insects are living on the rock shown in the photo below.
The most noticeable things on the rock are the "windsocks" billowing in the current. These silk nets are made by tube-making caddisfly larvae. These fairly large funnel-shaped, or bag-shaped, catch nets are spun and hung in the current to collect food particles/organisms on which the caddisfly larvae feed.
These particular tube-weaving caddisfly larvae prefer to set up shop by hanging out their "windsocks" in the gentler currents of the river.
   Another abundant inhabitant of this section of Susquehanna River are one kind of case-building caddisflies.  These caddisfly larvae are also filter-feeders. The river brings them their food... all they do is snag it. These caddisfly larvae collect food particles by holding their legs up into the current -  like the larva in the photo below (center right).  The larva are equipped with combs on their legs which collect fine particulate organic matter, FPOM.
These caddisfly cases are present on many of the rocks in our river.  They are more visible on the cobbles in the swift water.
Water shoes and snorkels anyone?
I'll post more about the windsock caddisflies and those tiny, trumpet-shaped cases on the rocks in the near future.  Oh, and notice the many tan "tents", or silk caddisfly nets, set up on the river bottom (photo above)... those are "way too cool" to pass up. I'll post about those as well.
Here is a previous post on aquatic life
What happens when a leaf falls into a stream

2 comments:

  1. Dana, that first photo is quite marvellous.

    I really enjoyed exploring the river with you, but now I have to go grab a towel as I'm dripping water on the floor.

    ReplyDelete
    Replies
    1. Sybil,
      Hey, we're used to wet floors... living by the water and all.

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