by Alex Patia.
Friday Harbor 6th
grade students arrived Wednesday last week to a chilly but beautiful late
autumn day here at the Environmental Learning Center. The big leaf maples (Acer
macrophyllum) are mostly bare
now and their bright yellow leaves now decorate the ground covered with
leopard-like dark dots created by tar spot fungus (Rhytisma punctatum). Whenever the clouds clear the surrounding
mountains Sourdough, Ruby, Pyramid and Colonial become visible and reveal a
snow line creeping lower and lower in elevation. It feels as though it
shouldn’t be too long before the snow finally sticks down here too and the Lake
Diablo area is transformed into a winter wonderland with snow coated Douglas
firs and white hills.
My trail group,
the Lynx, were already making great observations their first day, noting
changes from dry Lodgepole pine forest up by Bust Brown field down to the
comparatively lush riparian forest alongside Deer creek. During an “Each-One,
Teach-One” lesson students learned from and taught each other about various
types of water quality tests, environmental factors that effect riparian health
and how numbers of macroinvertebrates (animals without backbones visible to the
naked eye) can tell us about water quality by whether or not they are pollution
tolerant or pollution intolerant.
Students
started off their second day developing a question related to water quality,
using the scientific method, which they could research out in the field. My
group was interested in finding whether or not dissolved Oxygen (DO) and pH
were tied at all to how many benthic macroinvertebrates could live there. Their
method involved each student looking under 5 cobble (fist sized) rocks to find
and collect macroinvertebrates, or as we dubbed them “macros”. After looking at
a map of the area students decided to conduct research at Fawn and Sourdough
creeks.
A trail group at work on Fawn Creek.
At Fawn creek
students were having trouble finding macroinvertebrates at first, but upon
closer inspection many of the rocks they had collected had some well-hidden
macroinvertebrates moving about. The most visible were little worm-like
creatures that inched about like leeches, which made some of the students a
little uneasy about reaching into the water, but the arrow-shaped creepy
crawlers turned out to be planarian or flatworms (Class Turbellaria). Students
were puzzled by some mysterious empty cases made up of very tiny pebbles, and
as they wondered where they came from some students noticed that when probed a
creature’s head would wiggle out one end of the case and wave it’s legs as if
to complain about the disturbance. Using the dichotomous key in their field
journals the students came to the conclusion that these were the case-building
larvae of Caddisflies (Order Trichoptera). The pH test showed the streams water
was a neutral 7 but the DO test did not end up working, too many air bubbles
may have been the problem.
Trail groups examine macroinvertebrates using ice-cube trays for collection.
At Sourdough
the only macroinvertebrates collected were Caddisfly larvae, which once again
were difficult to spot looking like just tiny clumps of gravel at first and
about half the time these cases were no longer occupied. Part of this lack of
macroinvertebrate diversity could likely be that just a few weeks ago this
creek was completely dried up. Once again the pH turned out to be neutral and
students opted to skip the seemingly fickle DO test.
Back at the
microscope lab students took a closer look at the macroinvertebrates they had
collected. One macroinvertebrate collected from Fawn creek was too small to
identify earlier but under the microscope turned out to be a Fishfly larva
(Order Megaloptera), a predator with a menacing pair of mandibles- when viewed
through a microscope. Students were curious to see if this Fishfly larva would
try to eat a flatworm so we placed them in the same dish. The Fishfly did
indeed try to bite the flatworm but the much larger flatworm pushed the larva
out of it’s way after a brief albeit dramatic struggle.
Poking around looking
for various creepy crawlers from amphibians to macroinvertebrates has always
been my favorite past time. Most people I hike with quickly grow tired of
waiting as I search under each and every accessible rock or log trying to find
these seldom seen or appreciated creatures, but the students from Friday Harbor
were just as excited as I was to find out what was lurking under each rock.
Thank you Friday Harbor students for being willing to get cold, wet and muddy
in the name of science and exploration! I hope you will visit the North
Cascades again but don’t forget there are many places to explore right in your
own backyard where there are rock and logs with all sorts of creepy crawlers
hiding under them waiting to be found!
Photos by Jessica Newley.