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- Subject: Wetland Destruction
- From: Christine Manninen <email@example.com>
- Date: Mon, 31 Aug 1998 07:57:11 -0400
- List-Name: GLIN-Announce
- Organization: Great Lakes Commission
Posted on behalf of John Lavelle <firstname.lastname@example.org>
Requiem for an Ecosystem
I've thought it fitting to post the following notes
as the only records of an wetland ecosystem lost to make
way for another parking lot and for more offices and stores.
The entire area has been stripped of trees and the grey
clay earth flattened and all the life recorded below,
wonders of nature as spectacular on their small scale
as any rainforest, have been obliterated without anyone
knowing they were there. Thus the quality of life is
Aug 30, 1998
Today, March 15, 1996, one of those extraordinary days
when the tremendous diversity and tenacity of life is hammered
into ones mind. At the end of the street I live on is one of
the last remaining wooded areas left in this city of rampant
housing developments. This entire area was once a massive
wooded swamp. These woods do not appear to have been farm land,
at least not recently. A little to the south of the hole the
plowing furrows can still be seen but in this section of
the woods no furrows are evident Each Spring, with the melting
of the snows, springs bubble up from underground and sinkholes
fill with water all through the woods.
For years, ever since the life in the waters of Lake Erie
has so fascinated me, I have long been curious of what form life
takes in the waters of this these swampy woods but had just
never gotten around to taking a look. Today I did.
About 200 yards into the woods at the base of a tree was a
sinkhole between 6 and 8 feet in diameter and at its deepest
point one foot in depth. The bottom of this large puddle is covered
with layers of decaying leaves making the water look black in color.
I really had no idea what life was found in such a place so I was
utterly shocked to find that this small hole is a regular organic
soup. The following is a chart listing the animals found, none of
the species are familiar to me from studying the Lake, but the
order they fall in is easy to discern.
March 15 sinkhole in woods (the actual sample was two liters)
animals per liter
Cyclopoid 2 species 47
Harpactacoids 2 species 59
Ostracods 2 species 66
Rotifers 2 species 8
Insect Mosquito 1.5
This is undoubtably an undercount and does not include the
large number of small protozoa. Half the the copepods were carrying
My oldest son, the mathematican, was kind enough to estimate how
many liters of water this sinkhole holds. His estimate was 219 liters.
Using his estimate of 219 liters and multiplying it to the number of
crustaceans in the sample means that this large puddle has over
The life cycle of these creatures must be a race against
time. By May this hole, depending on the amount of rain, will
be a dry hole. The thousands of young copepods must reach
maturity, mate and have eggs deposited in the mud before the
hole dries out.
A whole array of questions spring to mind concerning this
ecosystem. The entire area appears to be interconnected by
underground springs. These springs can be found bubbling to
the surface at various spots in the woods. I have to wonder
if these sinkholes are also outlets for the springs? How old
is this small ecosystem? Is there any connection between the
animals found here now and the animals that once inhabited
the Lake when the Lake extended over this area? If such a
large number of animals are all drawing oxygen from the
hole and if the decaying leaves also cause a loss of oxygen
how do the animals survive the anaerobic conditions (this
is not a problem if the spring feeds into the sinkhole)?
March 16, 1996
I couldn't wait. After returning the animals to their
hole yesterday questions kept arising. Yesterday I didn't
take a sample right at a spring bubbling up from the ground.
The water there was only about three inches deep and the
depression was only about 2 feet across. Today I gave the
little puddle a look. This small spring's bottom is mud and
the water coming out from the ground flows across the
puddle and disappears below the ground. The spring is
like an an incredibly short stream.
>From Spring. 1 liter sample.
number in sample
Cyclopoids 4 1 species (the smaller one seen yesterday)
no eggs 1.5 mm. in length
Harpactacoid 3 1 species, the dark one from yesterday.
2 have eggs 1.5mm. in length
Nematode 1 1 mm. in length
After finishing this sample I had to see what another
March 16, 1996 (Actual sample was 2 liters)
Second sinkhole, this one is about 100 yards Northeast
of the first hole (March 15, 1996). This hole is about
a foot smaller in diameter (5 ft.) then the hole of
3/15 but was several inches deeper. The water from both
sinkholes smelled of sulphur.
>From 2nd sinkhole 2 liter sample
number per liter
Cyclopoids 6 1 species (the larger one seen in
first sample, not the one found in the
spring). size 2 to 3 mm.
Ostracods 43 1 species (the smaller one seen on the
the 15) size 1mm.
Nauplius 3.5 size .25 mm.
Mosquito larvae 7
Rotifer .5 Different species then seen on 15th.
Planarians 1 Not Dugesia body type, they have no
floppy "ear" points. Body does not
have spots, rather they have a vein
like pattern on inside of body.
4 to 6 mm. long
The difference between the three samples are striking.
sinkhole 1 sinkhole 2 spring
Cyclopoid 2 species 47 1 species 6 1 species 4
Nauplius 528 3.5 0
Harpactacoids 2 species 59 0 1 species 3
Ostracods 2 species 66 1 species 43 0
Rotifers 2 species 8 1 species 0.5 0
Insect Mosquito 1.5 Mosquito 7 0
Planarian 0 1 0
Nematode 0 0 1
The large broad cyclopoid found in Sinkhole 1 is also
found in sinkhole 2 but not in the spring. The cyclopoid in
the spring is the smaller cyclopoid found in sinkhole 1.
Only the smaller Ostracod is found in sinkhole 2. The
rotifer found in sinkhole is different from either of
the rotifers in sinkhole one.
Again, nothing but questions, foremost: why such a
large difference in both number of animals and species
found between the two sinkholes? Most specifically: why
does sinkhole 1 support twice the number of species
and over ten times the number of animals as sinkhole 2?
Is the environment that much different between the two
holes? Could the difference be just one of timing, one
pool's fauna developing before another? I refuse to believe
that the animals have not been able to transport themselves
between pools, but it is possible.
The world keeps getting bigger and bigger. More mysterys,
more doors to open. What do people do when not discovering
March 17, 1996
I've sadly been busy, between making a living
and keeping the research going on the Lake there hasn't
been much time for investigating the sinkholes. I have
managed to get out to the woods twice since March 16 and
the following are the notes from two trips.
April 24, 1996
This sample was taken at a deep sinkhole, larger and
deeper then the holes sampled before. This hole is a circle
about 5 feet in diameter and 2 feet deep. The water is black
and the bottom is covered with decaying leaves.
2 Liter sample
A clam, the other numbers are pretty impressive, but a
clam. Is this ecosystem a remnant of the ancient swamp that
covered this region before this land was settled and the
swamps drained. Little things like this startle me. I just
get use to these puddles being biological soups when the
waters shock me by throwing a clam into the sample. The
last aquatic animal I would have expected to find.
June 19, 1996
The summer so far has been very wet. So far the area
has had about 2 inches more rain then is normal. Mosquitos
are everywhere. I went searching for the sinkhole last
visited on April 24. Even with all the rainfall all the
sinkholes have disappeared. I went all through the woods,
getting bitten by the little blood suckers, sweating till
I felt soaked, getting caked with mud, but there was not
a sinkhole to be found. Finally went to the one area of the
woods that can be thought of as a swamp. When ever rain falls
in any appreciable amount this roughly ten square yard area
fills with water. This small swamp was still extensively
covered by water so here the sample was taken. Unlike the
sinkholes this areas water bottom is not covered by decaying
leaves, rather an unusual type of grass grows covering the
The water in the sample was so thick with sediment that
only a 1/2 liter sample was able to be filtered on this
evening. To give an indication of how thick the water was
I started filtering, then took a shower, watched a
half hour television show, set up the equipment and during
all this time only 1/2 liter had filtered even though I had
changed the filter 3 times. This was water with a lot of
Swamp sample .5 liters
Cyclopoid copepods 40
CALANOID COPEPODS 5
There were two very strange protozoans. I would gladly
give my dog's canine teeth to know what these really unusual
You may have the noticed the capitalizing of the Calanoid
copepods. Calanoids are refer to over and over again in
the literature on crustaceans as "... almost exclusively
planktonic in the pelagial (open waters) zone."1 As anyone
who has read the work done here on crustaceans in the Lake
is aware of by now this just ain't so. This is no where
shown more then finding these copepods here in 6 inches of
water in small land locked swamp that dries up continually
through out the year.
A comparison can not be made between the swamp animals
and those found in the sinkholes. The ostracods appear to
be a completely different species and there were no Calanoid
in any of the sinkholes. I can not tell if there is a difference
in the Cyclopoids. The chemistry of the water is undoubtably
In the following chart I have decided to drop the sample
taken from the spring as that environment appears to be
completely different from the sinkholes. The data is in
some ways just what you would expect to find. The large naulpius
population of middle March has matured bringing about the large
Cyclopoid population of April 24. The mosquito larvae
population has increased in April as this is probably the second
generation. Other comparisons are not so easy to make. Remember
these are three different sinkholes being compared. So whether
the Harpactacoid population has decreased and the Ostracod
population has increased is not shown by the data but the
data does point to a possible trend that would be fun to
March 15 March 16 April 24
sinkhole 1 sinkhole 2 sinkhole
Cyclopoid 2 species 47 1 species 6 1 species 216
Nauplius 528 3.5 1
Harpactacoids 2 species 59 0 1 species 0
Ostracods 2 species 66 1 species 43 184
Rotifers 2 species 8 1 species 0.5 0
Insect Mosquito 1.5 Mosquito 7 25
Planarian 0 1
Nematode 0 0 1
Clam 0 0 0
As I stated in the first set of notes concerning the sinkholes
these animals faced a race against time. I did not realize when
I wrote that just what a mad race these creatures faced. From
the time the waters unfreezes in late Febuary till perhaps the
middle of June of earlier these animals must hatch, mature and
reproduce. I wish I knew whether the animal go into a type of
hibernation (known as diapause) or whether they die out leaving
only eggs to form the next generation. The fingernail clam
is especially intriguing and I'll have to do some research in
order to discover whether clams die or whether they to go into
Over and over again I wonder how old the ecosystems of these
sinkholes are. Especially with the finding of the clam and
(and the Calanoid copepod in the swamp) I can imagine these
systems as being very old. Not only must all the different
species be transported to these little water holes the creatures
must also have been already adapted to high degree to withstand
the sudden changes that occur in their habitat.
How much the chemistry of the water in each sinkhole differs
and how that difference in chemistry determines what animals
are able to thrive in a particular sinkhole is also a
1 Wetzel, Robert G. "Limnology" 1975.
Nov. 17, 1996
With the early snow fall and cold temperatures I
thought to look at the sinkholes once again. The
following sample was taken from the large sinkhole
that was sampled on April 24, 1996. In April the
water was black, probably due to the decaying
leaves found at the sinkhole's bottom. In November the
water was almost clear, having only a slight
yellowish-brown hue. This color difference is no doubt
due to the leaves having only just recently fallen leaving
little time for decomposition.
About a 2 liter sample # in sample size
Cyclopoid Copepods 73 .75mm to 2 mm.
Harpactacoida 72 1.5mm.
small 14 a little less then .5mm
large 6 1.5 to 2mm
Bivalves 5 2 to 4 mm. diameter
Rotifers (one species) 2 1 mm
Collumbolla (both dead) 2 1.5 to 3 mm.
Nematodes 2 1.5 to 2 mm.
Note no nauplius in sample
This sinkhole is the same one the first clam
was found in. In this sample the 5 fingernail clams were
all found in the top water. These clams apparently
are not buried in the mud but live on top of the submerged
fallen leaves. The clams, after burying themselves in the
mud when the water of the hole evaporates, must climb out
of the mud and work they way through to the top of the
An understanding of clam physiology is necessary to
appreciate how difficult a task such a climb must be.
A clam has only one soft extendable foot to work with.
The task a clam faces can be imagined by the macabre image
of a disembodied human head with the tongue being the
only means the head has for locomotion. The tongue would
be able to extend to a length slightly greater then the
head size and would also exude a sticky substance. The
head, buried in the mud, must dig out using only the tongue,
pull the head up and then negotiate layer after layer of soft
leaf litter until finally arriving at the surface. In the
Spring this whole process must be reversed, going back
through the litter, digging a new hole, and then burying
itself back into the mud. While the distance the clam must
cover is not great, perhaps only 2 inches, the feat is
never the less a prodigious one.
No copepod nauplii were found in this sample. The last
sample taken in April of this year only had one nauplius.
The Fall sample had none, the Spring sample had one. This
may be a clue to the life cycle of the crustaceans. Depending
on when the sinkhole filled with water the crustaceans may
not all die off when the waters of the hole disappears. The
crustaceans may be summering over in a state of diapause,
diapause can roughly be thought of as analogous to mammalian
hibernation, rather than all the animals being newly hatched
from eggs. This question is impossible to answer from the
data so far gathered because the samples taken from different
sinkholes have such a wide disparity in the number of animals
March 15 March 16 April 24 Nov. 17
sinkhole 1 sinkhole 2 sinkhole 3 sinkhole 3
Nauplius 528 3.5 1 0
Only the samples taken on April 24 and Nov. 17 were taken
from the same sinkhole. What makes me think the animals are
not a new generation is that both the last sample taken on
April 24 had only one nauplii and the first sample taken on
Nov. 17 had none. The most important question than is when
did the sinkhole first fill with water and in what state
were the animals at that time; a question I can't answer.
The woods in November is a dreary place. The time of new
fallen dried leaves crackling underfoot is gone and the
time of beauty that comes with fresh fallen snow has not yet
arrived. The woods may not have the look of death, but it does
give the sense of deeply sleeping. The plant life
driven by the sun's power has ceased operating but the
chemicals energy stored in the leaf litter on the ground
brings to life an ecosystem whose foundation
depends on the decaying leaves. How exactly this food web
operates I don't know. I imagine the leaves are attacked
first by bacteria. The bacteria is consumed by protozoa.
The crustaceans and bivalves consume the protozoa. Probably
some or all of the members of the food web consume the
detritus of leaves acted on by the bacteria. The big
problem in this web is the depletion of oxygen. All of
the processes involved in the chemical breakdown of the
leaves tend to rob the water of this small hole of the
oxygen necessary for respiration. Some genera of the
ostracods, cyclopoid, and Sphaeriidae can survive long
periods of oxygen depletion, but there is a big difference
between surviving and thriving. These animals appear to
be active and breeding in this environment even though
the oxygen content of the water may be diminishing. Getting
a grip on the oxygen level is paramount to
understanding the system. What I don't know is whether the
the oxygen is being replenished by an underground spring
or water seeping into the hole from the surrounding land.
The land, sleeping, gives birth to an ecosystem that
comes alive in the Fall. At the beginning of this essay
I used the phrase "summering over". The phrase "wintering
over" is used to describe hibernation or diapause by
animals in winter. "Summering over", well, I just made the
phrase up, means the same thing as wintering over, just the
animals sleep in summer. This awakening in Fall is a
marvelous wonder, all around life is taking a pause, but
in this small water hole, fueled by the discards of the
trees, life burst anew in a totally different time frame
then the surrounding ecosystem.
At the north end of the street I live on is one of the
worlds largest freshwater ecosystems, a wilderness in which
very few of the life processes are understood. At the south
street end lies a small woods which holds small pools of
water bursting with life. The life of these small holes
may be the last remanents of the animals that once
inhabited this area before the vast swamp was drained.
The two ecosystem interestingly run on almost opposite
time. The Lake in November is at its nadir in terms of
animal life in the plankton, but the sinkhole in the
woods is just beginning to switch into high gear.
I speculate the opposite nature of the life cycles is
caused by the difference in the primary direct source
of energy for each of the ecosystems. The Lake's photoplankton
is receiving less and less sunlight as the days get shorter
while the sinkhole in getting more nutrient enriched as the
bacteria has more time to breakdown the decaying leaves.
What a place to live, the two ecosystem are so extremely
differrent that it is like having the polar ice caps and
the tropical rainforest both within walking distance.