James G. (James George) Needham.

The life of inland waters; an elementary text book of fresh-water biology for students online

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Online LibraryJames G. (James George) NeedhamThe life of inland waters; an elementary text book of fresh-water biology for students → online text (page 4 of 26)
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land, chiefly as rain, snow and hail.

They are not distributed uniformly over the face of
the continents for each continent has its humid regions
and its deserts. Rainfall in the United States varies
from 5 to 100 inches per annum. Two-thirds of it
falls on the eastern three-fifths of the country. For the
Eastern United States it averages about 48 inches, for
the Western United States about 12 inches ; the average
for the whole is about 30 inches. The total annual
precipitation is about 5,000,000,000 acre-feet.*

*An acre-foot is an acre of water i foot deep or 43,560 cubic feet of water.


56 Water and Land

It is commonly estimated that at least one-half of
this rainfall is evaporated, in part from soil and water
surfaces, but much more from growing vegetation; for
the transpiration of plants gives back immense quanti-
ties of water to the atmosphere. Hellriegel long ago
showed that a crop of corn requires 300 tons of water
per acre : of potatoes or clover, 400 tons per acre. At
the Iowa Agricultural Experiment Station it was shown
that an acre of pasturage requires 3,223 tons of water,
or 28 inches in depth (2% acre-feet). Before the days
of tile drainage it was a not uncommon practice to
plant willow trees by the edges of swales, in order that
they might carry off the water through their leaves,
leaving the ground dry enough for summer cropping.
The rate of evaporation is accelerated also, by high
temperatures and strong winds.

The rain tends to wet the face of the ground every-
where. How long it will stay wet in any given place
will depend on topography and on the character of the
soil as well as on temperature and air currents. Show-
ers descending intermittently leave intervals for com-
plete run-off of water from the higher ground, with
opportunity for the gases of the atmosphere to enter
and do their work of corrosion. The dryer intervals,
therefore, are times of preparation of the materials
that will appear later in soil waters. Yet all soils in
humid regions retain sufficient moisture to support a
considerable algal flora. Periodical excesses of rainfall
are necessary also to maintain the reserve of ground
water in the soil. Suppose, for example, that the 35
inches of annual rainfall at Ithaca were uniformly
distributed. There would be less than one-tenth of an
inch of precipitation each day an amount that would
be quickly and entirely evaporated, and the ground
would never be thoroughly wet and there would be no
ground water to replenish the streams. Storm waters

Soil and Stream-flow 57

tend to be gathered together in streams, and thus about
one-third of our rainfall runs away. In humid areas
small streams converge to form larger ones, and flow
onward to the seas. In arid regions they tend to
spread out in sheet floods, and to disappear in the sands.

In a state of nature little rain water runs over the
surface of the ground, apart from streams. It mainly
descends into the soil. How much the soil can hold
depends upon its composition. Dried soils have a
capacity for taking up and holding water about as fol-
lows: sharp sand 25%, loam 50%, clay 60%, garden
mould 90% and humus 1 80% of their dry weight. Water
descends most rapidly through sand and stands longest
upon the surface of pure clay. Thick vegetation with
abundant leaf fall, and humus in the soil tend to hinder
run-off of storm waters, and to prolong their passage
through the soil. Thus the excess of rainfall is gradually
fed into the streams by springs and seepage. Under
natural conditions streams are usually clear, and their
flow is fairly uniform.

Unwise clearing of the land and negligent cultivation
of the soil facilitate the run-off of the water before the
storm is well spent, promote excessive erosion and
render the streams turbid and their volume abnormally
fluctuating. Little water enters the soil and hence the
springs dry up, and the brooks, also, as the seepage of
ground water ceases. Two great evils immediately
befall the creatures that live in the streams and pools:
(i) There is wholesale direct extermination of them with
the restriction of their habitat at low water. (2) There
occurs smothering of them under deposits of sediment
brought down in time of floods, with indirect injury to
organisms not smothered, due to the damage to their
foraging grounds.

The waters of normal streams are derived mainly
from seepage, maintained by the store of water accumu-

53 Water and Land

lated in the soil. This store of ground water amounts
according to recent estimates to some 25% of the bulk
of the first one hundred feet in soil depth. Thus it
equals a reservoir of water some 25 feet deep covering
the whole humid eastern United States. It is con-
tinuous over the entire country. Its fluctuations are
studied by means of measurements of wells, especially
by recording the depth of the so-called "water table."
On the maintenance of ground water stream-flow and
organic productiveness of the fields alike depend.




UT of the atmosphere
comes our water supply
the greatest of our
natural resources. It
falls on hill and dale,
and mostly descends
into the soil. The ex-
cess off-flowing from the

surface and outflowing from springs and seepage, forms
water masses of various sorts according to the topog-
raphy of the land surface. It forms lakes, streams or
marshes according as there occur basins, channels or
only plant accumulations influencing drainage.

The largest of the bodies of water thus formed are
the lakes. Our continent is richly supplied with them,
but they are of very unequal distribution. The lake
regions in America as elsewhere are regions of compara-
tively recent geological disturbance. Lakes thickly
dot the peninsula of Florida, the part of our continent
most recently lifted from the sea. Over the northern
recently glaciated part of the continent they are


60 Types of Aquatic Environment

innumerable, but in the great belts of corn and cotton,
and on the plains to the westward, they are few and
far between. They are abundant in the regions of more
recent volcanic disturbance in our western mountains,
but are practically absent from the geologically older
Appalachian hills. They lie in the depressions between
the recently uplifted lava blocks of southern Oregon.
They occur also in the craters of extinct volcanoes.
They are apt to be most picturesque when their setting
is in the midst of mountains. There are probably no
more beautiful lakes in the world than some of those in
the West, such as Lake Tahpe (altitude 6200 ft.) on the
California-Nevada"baun3ary, and Lake Chelan in the
state of Washington*, to say nothing of the Coeur
d'Alene in Idaho and Lake Louise in British Columbia.
Eastward the famous lake regions that attract most
visitors are those of the mountains of New York and
New England, those of the woodlands of Michigan and
Wisconsin and those of the vast areas of rocks and water
in Canada.

Lakes are temporary phenomena from the geologists
point of view. No sooner are their basins formed than
the work of their destruction begins. Water is the
agent of it, gravity the force employed, and erosion
the chief method. Consequently, other things being
equal, the processes of destruction go on most rapidly
in regions of abundant rainfall. Inwash of silt from
surrounding slopes tends to fill up their basins. The
most extensive filling is about the mouths of inflowing
streams, where mud flats form, and extend in Deltas
out into the lake. These deltas are the exposed sum-
mits of great mounds of silt that spread out broadly
underneath the water on the lake floor. At the shore-
lines these deposits are loosened by the frosts of winter,

*Descriptions of these two lakes will be found in Russell's Lakes of North

Lakes Temporary Phenomena


pushed about by the ice floes of spring, and scattered
by every summer storm, but after every shift they set-
tle again at lower levels. Always they are advancing
and rilling the lake basin. The filling may seem slow
and insignificant on the shore of one of the Great Lakes
but its progress is obvious in a mill pond, and the dif-
ference is only relative.

FIG. 12. An eroding bluff on the shore of Lake Michigan that is receding at
the rate of several feet each year. The broad shelving beach in the fore-
ground is sand, where the waves ordinarily play. Against the bare rising
boulder-strewn strip back of this, the waves beat in storms; at its summit
they gather the earth-slides from the bank above and carry them out into
the lake. The black strip at the rear of the sand is a line of insect drift,
deposited at the close of a midsummer storm by the turning of the wind on

On the other hand, lakes disappear with the cutting
down of the rim of their basins in outflow channels. The
Niagara river, for example, is cutting through the lime-


Types of Aquatic Environment

stone barrier that retains Lake Erie. At Niagara
Falls it is making progress at the rate of about five feet
a year. Since the glacial period it has cut back from
the shore of Lake Ontario a distance of some seventeen
miles, and if the process continues it will in time
empty Lake Erie.

FIG. 13. Evans' Lake, Michigan; a lake in process of being filled by encroach-
ment of plants. A line of swamp loose-strife (Decodon) leads the invading
shore vegetation. Further inwash of silt or lowering of outlet is precluded
by density of the surrounding heath. The plants control its fate.

Photo by E. McDonald.

When the glacier lay across the St. Lawrence valley,
before it had retreated to the northward, all the waters
of the great lakes region found their way to the ocean
through the Mohawk Valley and the Hudson. At that
time a similar process of cutting an outlet through a
limestone barrier was going on near the site of the
present village of Jamesville, New York, where on the

The Great Lakes

Clark Reservation one may see today a series of
abandoned cataracts, dry rock channels and plunge
basins. Green Lake at present occupies one of these
old plunge basins, its waters, perhaps a hundred feet
deep, are surrounded on all sides but one, by sheer
limestone cliffs nearly two hundred feet high.

When lakes become populated then the plants and
animals living in the water and about the shore line
contribute their remains to the final filling of the basin.
This is well shown in figure 13.

The Great Lakes con-
stitute the most magnifi-
cent system of reservoirs
of fresh water in the world ;
five vast inland seas,
whose shores have all the
sweep and majesty of the
ocean, no land being visi-
ble across them. All but
one (Erie) have the bot-
tom of their basins below
the sea level. Their area,
elevation and depth are
as follows:

FIG. 14. The larger lakes and rivers of
North America.

Surface Depth in feet
alt. in ft. meant maximum

Area in
sq. mi.

Lake Ontario 7.240 247 300 738

Erie 9.960 573 70 210

Huron* 23.800 581 250 730

" Michigan 22.450 581 325 870

" Superior 31.200 602 475 1.008

"Including Georgian Bay.
f Approximate.

They are stated by Russell to contain enough water
to keep a Niagara full-flowing for a hundred years.

64 Types of Aquatic Environment

The Finger Lakes of the Seneca basin in Central New
York constitute an unique series occupying one section
of the drainage area of Lake Ontario, with which they
communicate by the Seneca and Oswego rivers. They
occupy deep and narrow valleys in an upland plateau
of soft Devonian shales. Their shores are rocky and
increasingly precipitous near their southern ends. The
marks of glaciation are over all of them. Keuka, the
most picturesque of the series, occupies a forking valley
partially surrounding a magnificent ice- worn hill.
The others are all long and narrow and evenly contoured,
without islands (save for a single rocky islet near the
east Cayuga shore) or bays.

The basins of these lakes invade the high hills to the
southward, reaching almost to the head- waters of
the tributaries of the Susquehanna River. Here
there is found a wonderful diversity of aquatic situa-
tion. At the head of Cayuga Lake, for example,
beyond the deep water there is a mile of broad shelving
silt-covered lake bottom, ending in a barrier reef.
Then there is a broad flood plain, traversed by deep
slow meandering streams, and covered in part by
marshes. Then come the hills, intersected by narrow
post-glacial gorges, down which dash clear streams
in numerous beautiful waterfalls and rapids. Back
of the first rise of the hills the streams descend more
slowly, gliding along over pebbly beds in shining
riffles, or loitering in leaf-strewn woodland pools.
A few miles farther inland they find their sources in
alder-bordered brooks flowing from sphagnum bogs and
upland swales and springs.

Thus the waters that feed the Finger Lakes are
all derived from sources that yield little aquatic
life, and they run a short and rapid course among
the hills, with little time for increase by breeding:
hence they contribute little to the population of the

The Finger Lakes

lake. They bring in constantly, however, a supply
of food materials, dissolved from the soils of the

Bordering the Finger Lakes there are no extensive
marshes, save at the ends
of Cayuga, and the chief
irregularities of outline
are formed by the deltas
of inflowing streams.
The two large central
lakes, Cayuga and Sen-
eca, have their basins
extending below the sea
level. Their sides are
bordered by two steeply-
rising, smoothly eroded
hills of uniform height,
between which they lie
extended like wide placid
rivers. The areas, eleva-

FIG. 15.

The Finger Lakes of Central
New York.

A, Canandaigua; B, Keuka; C, Seneca; D,
Cayuga; E.Owasco; F, Skaneateles; G, Otisco;

^ 1 . H, the Seneca River; I , The arrow indicates the

and deDthS Of the location of the Cornell University Biological
f ^ Pield station at Ithaca. The stippled area at

re aS lOllOWS : the opposite end of Cayuga Lake marks the

location of the Montezuma Marshes.

sq. mi.

Lake Skaneateles 13.9

" Owasco 10.3

" Cayuga 66.4

Seneca 67.7

" Keuka 18.1

Canandaigua 16.3

Birge and Juday found the transparency of four of
these lakes as measured by Secchi's disc in August, 1910,
to be as follows:

Canandaigua 12.0 ft. Seneca 27.0 ft.

Cayuga 16.6 ft. Skaneateles 33.5 ft


Depth in feet

alt. in ft.






















Types of Aquatic Environment

The Lakes of the Yahara Valley in Southern Wisconsin
are of another type . They occupy broad , shallow basins
formed by the deposition of barriers of glacial drift

in the preglacial course of
the Yahara River. Their
outlet is through Rock
River into the Missis-
sippi. Their shores are
indented with numerous
bays, and bordered ex-
tensively by marshes.
The surrounding plain is
dotted with low rounded
hills, some of which rise
abruptly from the water,
making attractive shores.
The city of Madison is
the location of the Uni-
versity of Wisconsin ,
which Professor Birge has
made the center of the
most extensive and care-
ful study of lakes yet
undertaken in America.
The area, elevation and
depth of these lakes is as
follows :


1 6. The four-lake region of
Madison, Wisconsin.

LakeKegonsa .
" Wabesa .
Monona .
" Mendota

Area in


Depth in feet

sq. mi.

alt. in ft.



















Floodplain Lakes 67

Lakes resulting from Erosion Although erosion tends
generally to destroy lakes by eliminating their basins,
here and there it tends to foster other lakes by making
basins for them. Such lakes, however, are shallow and
fluctuating. They are of two very different sorts,
floodplain lakes and solution lakes.

Floodplain Lakes and Ponds Basins are formed in
the floodplains of rivers by the deposition of barriers
of eroded silt, in three different ways.

1 . By the deposition across the channel of some large
stream of the detritus from a heavily silt-laden tributary
stream. This blocks the larger stream as with a partial
dam, creating a lake that is obviously but a dilatation
of the larger stream. Such is Lake Pepin in the
Mississippi River, created by the barrier that is de-
posited by the Chippewa River at its mouth.

2. By the partial filling up of the abandoned chan-
nels of rivers where they meander through broad
alluvial bottom-lands. Phelps Lake partly shown in
the figure on page 50 is an example of a lake so formed;
and all the other lakes of that figure are partly occluded
by similar deposits of river silt. Horseshoe bends are
common in slow streams, and frequently a river will cut
across a bend, shortening its course and opening a
new channel; the filling up with silt of the ends of the
abandoned channel results in the formation of an "ox-
bow" lake; such lakes are common along the lower
course of the Mississippi, as one may see by consult-
ing any good atlas.

3. By the deposition in times of high floods of the
bulk of its load of detritus at the very end of its course,
where it spreads out in the form of a delta. Thus a
barrier is often formed on one or both sides, encircling a
broad shallow basin. Such is Lake Pontchartrain at
the left of the ever extending delta of the Mississippi.


Types of Aquatic Environment


Solution Lakes and Ponds Of very different charac-
ter are the lakes whose basins are produced by the
dissolution of limestone strata and the descent of the
overlying soil in the form of a "sink." This is erosion,
not by mechanical means at first, but by solution. It

occurs where beds of soluble strata
lie above the permanent ground
water level, and are themselves
overlaid by clay. Rain water
falling through the air gathers
carbon dioxide and becomes a
solvent of limestone. Percolat-
ing downward through the soil it
passes through the permeable
carbonate, dissolving it and
carrying its substance in solution
to lower levels, of ten flowing out
in springs. As the limestone is
thus removed the superincum-
bent soil falls in, forming a sink
hole. The widening of the hole,
by further solution and slides
results in the formation of the
pond or lake, possibly, at the
beginning, as a mere pool.

The area of such a lake is doubtless gradually
increased by the settling of the bottom around the
sink as the soluble limestone below is slowly carried
away. Its configuration is in part determined by the
original topography of the land surface, and in part by
the course of the streamflow underground : but its bed
is unique among lake bottoms in that all its broad
shoals suddenly terminate in one or more deep funnel-
shaped outflow depressions.

Lime sinks occur over considerable areas in the south
ern states, and in those of the Ohio Valley, but perhaps

FIG. 17. Solution lakes of
Leon County, Florida,
(after Sellards).

The white spots in the lakes indi-
cate sinks.

A. Lake lamonia; area at high
water 10 sq. mi.

B. Lake Jackson; area 7 sq. mi.

C. Lake Lafayette; area 3K
sq. mi.

D. Lake Miccosukee; area 1 % sq.
mi.; depth of north sink 28 ft.
Water escapes through this sink
at the estimated rate of 1000
gals, per minute.

O. Ocklocknee River; S, St.
Mark's River; T, Tallahassee.

Solution Lakes



the best development of lakes about them is in the
upland region of northern Florida. These lakes are
shallow basins having much of their borders ill-defined
and swampy. Perhaps the
most remarkable of them is
Lake Alachua near Gaines-
ville. At high water this
lake has an area of some
twenty-five square miles and
a depth (outside the sink) of
from two to fourteen feet.
At its lowest known stage it
is reduced to pools filling
the sinks. During its re-
corded history it has several
times alternated between
these conditions. It has
been for years a vast ex-
panse of water carrying
steamboat traffic, and it has
been for other years a broad
grassy plain, with no water
in sight. The widening or
the stoppage of the sinks
combined with excessive or
scanty rainfall have been
the causes of these remark-
able changes of level.

The sinks are more or
less funnel-shaped openings
leading down through the soil into the limestone.
Ditchlike channels often lead into them across the lake's
bottom. The accompanying diagram shows that they
are sometimes situated outside the lake's border, and
suggest that such lakes may originate through the
formation of sinks in the bed of a slow stream.


FIG. 1 8. Lake Miccosukee, (after
Sellards), showing sinks; one in
lake bottom at north end, two in
outflowing stream, 2> miles dis-
tant. Arrows indicate normal
direction of stream flow, (reversed
south of sinks in flood time when
run-off is into St. Mark's River).

Types of Aquatic Environment

Such lakes, when their basins lie above the level of
the permanent water table, may sometimes be drained
by sinking wells through the soil of their beds. This
allows the escape of their waters into the underlying
limestone. Sometimes they drain themselves through
the widening of their underground water channels.
Always they are subject to great changes of level conse-
quent upon variation in rainfall.

Enough examples have now been cited to show how
great diversity there is among the fresh-water lakes of
North America. Among those we have mentioned are
the lakes that have received the most attention from
limnologists hitherto ; but hardly more than a beginning
has been made in the study of any of them. Icthyolo-
gists have collected fishes from most of the lakes of the
entire continent, and plancton collections have been
made from a number of the more typical : from Yellow-
stone Lake by Professor Forbes in 1 890 and from many
other lakes, rivers and cave streams since that date.

Lakeside laboratories On the lakes above mentioned
are located a number of biological field stations. That
at Cornell University is at the head of Cayuga Lake.
That of the Ohio State University is on Gibraltar Island
in Lake Erie, near Put-in-Bay, Ohio. That of the Uni-
versity of Pittsburgh is on the shore of the same lake
at Erie, Pennsylvania. The biological laboratories of
the University of Wisconsin are located directly upon
the shore of Lake Mendota, and a special Lake Limno-
logical Laboratory is maintained at Trout Lake. The
University of Florida at Gainesville is conveniently near
to a number of the solution lakes of northern Florida.
Elsewhere there are other lakeside research stations
among which we may mention the following:

That of the University of Michigan is on Douglas
Lake in the northern end of the southern peninsula of

Depth and Breadth 71

That of the University of Indiana is on Winona Lake,
a shallow hard water lake of irregular outline, having
an area of something less than a square mile.

That of the University of Iowa is on Okoboji Lake
near Milford, Iowa. That of the University of Minne-
sota is on Lake Itasca, the source of the Mississippi
River, in Itasca Park. That of the University of Vir-
ginia is at Mountain Lake (altitude 4000 ft.). That of
Brigham Young University is on Utah Lake near Provo,
Utah. That of the Tennessee Academy of Science is
on Reelfoot Lake (a large shallow lake formed by an
earthquake in 1811) near Memphis.

Under the direction of the Biological Board of Can-
ada, which has its headquarters at the University of
Toronto, much survey work is being done on Canadian
lakes throughout the interior provinces, in cooperation
with that University, with the provincial universities
of Manitoba and Saskatchewan, and with Queen's Uni-
versity at Kingston. This work, like the survey work
of the U. S. Bureau of Fisheries, is mainly done from
temporary field stations, without the establishment of
permanent laboratories.

Depth and Breadth The depth of lakes is of more
biological significance than the form of their basins;
for, as we have seen in the preceding chapter, with
increase of depth goes increased pressure, diminished
light, and thermal stratification of the water. Living
conditions are therefore very different in shallow water
from what they are in the bottom of a deep lake, where
there is no light, and where the temperature remains
constant throughout the year. Absence of light pre-

Online LibraryJames G. (James George) NeedhamThe life of inland waters; an elementary text book of fresh-water biology for students → online text (page 4 of 26)