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Limnology
Limnology is the study of inland waters.
This includes rivers, creeks, billabongs,
ponds, pools, swamps, lakes, salt lakes and other wetlands.
The word limnology comes from the Greek
word "limne", meaning marsh.
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Florida Lake Watch | Secchi Disk |
| American Rivers |
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Watershed |
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Limnologists study:
Eutrophication
Groundwater/Surface Water Interaction
Oxygen Budgets
Sediment Mapping and Analysis
Lake Origins
Glacial
Tectonic
Volcanic
Lake Stratification
 | Amictic - never mix. Sealed totally by ice. Arctic Lakes, high Alpine Lakes. | ||||||||||||
| Oligomictic- (few) rare circulation. Usually tropical well
above 4 C all year. | ||||||||||||
| Monomictic- (one) mixes once a year. Won't usually
stratify. Good example of Florida lakes.
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| Polymictic-
(many)
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| Dimictic- (two) mixes twice a year, fall and spring overturn.
Above 4 C and below 4 C. | ||||||||||||
| Holomictic- (whole) entire column circulates from surface to bottom. | ||||||||||||
| Meromictic- never totally circulates, very deep, usually tectonic.
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| Ectogenic meromictic- external source of salt flowing into lake | ||||||||||||
| Crenogenic meromictic- submerged saline springs | ||||||||||||
| Biogenic meromictic- accumulation of salts due to sediments |
C,
ex. Canada 
C, subtropical,
Florida 
C, tropical, high altitude
C, tropical, equatorial
Temperate
Lake Overturn
(Northern Lakes)
Temperature
Temperature has a direct effect on living
organisms in the lake system. Dissolved oxygen levels are directly related
to temperature which in turn effects zooplankton and other aquatic life.
...located in Florida, second largest
freshwater lake contained entirely within the lower
48 states of the U.S.
Great Lakes
The Laurentian Great Lakes of North America were formed 10,000 to 15,000 years ago and consist of five major lakes: Lakes Superior, Huron, Michigan, Erie, and Ontario. This lake district contains more fresh water (greatest unfrozen mass) than any other in the world.
Dissolved Oxygen
Dissolved oxygen is an essential indicator in assessing a water-body's health. Oxygen enters the water from the atmosphere and through aquatic plant and phytoplankton photosynthesis. The oxygen is then available for aquatic organisms to utilize in basic metabolic processes. Most plants and animals can grow and do well when the dissolved oxygen level exceeds 5 mg/l. A drop in the level to 3-5 mg/l causes organisms to become stressed. Levels below 3 mg/l causes death in many species. Oxygen is used up during the decomposition of organic material. An overload of nutrients from human activities cause overgrowth of phytoplankton. The phytoplankton ultimately die and fall to the bottom where they decompose, using up oxygen.
Nitrogen & Phosphorus
The same nutrients - phosphorus (P) and nitrogen
(N) that fertilize our lawns, also "fertilize" our river, lakes, ponds and
streams. Our rivers, lakes, ponds and streams don't need fertilizing.
In fact, many area streams, lakes and ponds are grossly over-fertilized
by nutrients, which come from storm water runoff and sewage treatment plant
discharges. These excess nutrients cause aquatic plants and algae to grow
over abundantly in the summer, a condition called eutrophication. This
prolific plant and algal
growth can ruin waterways for boating, fishing and swimming.
The uncontrolled growth also harms fish and other aquatic life by changing
the amount of dissolved oxygen in the water system.
Floridan Aquifer
Florida has over 50,000 miles of rivers
and streams, 7800 lakes, and 4000 square miles of estuaries, with an abundance
of surface waters that are used for a variety of purposes.
A river system consists of a main channel and all of the tributaries that flow into it. Within a river system, the surface of the ground slopes toward the network of tributaries, so the drainage system acts as a funneling mechanism for removing surface runoff and weathered rock debris.
| tributary | a stream flowing into or joining a larger stream |
| distributary | any of the numerous stream branches into which a river divides where it reaches its delta |
| upstream | moves toward headwater (up the regional slope of erosion) |
| downstream | moves toward mouth of river (delta) |
| delta | a large, roughly triangular body of sediment deposited at the mouth of a river |
| meander | a broad, looping bend in a river |
Order
1st order streams have no tributaries
2nd order streams are where two 1st order
streams meet
3rd order streams are where two 2nd order
streams meet
4th order streams are where two 3rd order
streams meet
Length of stream > with order number, .5 relationship to slope
Springs
Florida has 17 to 27 springs (depending
on the resource), many of which are 1st order. Silver Springs,
located in Marion County, is the largest 1st order spring in the United
States, with a flow rate of
808 cubic feet per second.
St. John's River
flows north
273 miles, longest river in Florida
Pollution
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Upper Clean Water Zone | ||||
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Pollution Source | ||||
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Zone of Degradation | ||||
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Anaerobic Zone | ||||
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Recovery Zone
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Lower Clean Water Zone |
pH scale
A logarithmic scale for expressing the acidity or
alkalinity of a solution. A pH below 7 indicates an acid solution; pH above 7 indicates an alkaline solution.
Chlorophyll bearing organisms which possess
unicellular sex organs
or multi-cellular ones in which every cell
forms a gamete.
Bluegreen algae is prokaryotic and the rest are eukaryotic
90% of oxygen in atmosphere is produced by algae
photosynthetic algae lack roots, steams and leaves
all algae contains chlorophyll a
Pigments:
Chlorophyll A, B, C, D
Carotenoids:
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Xanthophylls:
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Zooplankton
Rotifers
Crustaceans Copepods
Zooplankton important to larval fish are classified as either rotifers, cladocerans (water fleas) or copepods.
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Rotifera
life span 12 days
Keratella
most common rotifer^
lecane
Rotifers are the first organism to invade
water systems.
Epiphanes brachionus
The name "rotifer" is derived from the Latin word meaning "wheel-bearer"; this makes reference to the crown of cilia around the mouth of the rotifer. The rapid movement of the cilia in some species makes them appear to whirl like a wheel. The general body plan of a rotifer consists of four basic regions: head, neck, trunk (body), and the foot. In most species, the head carries a corona (crown) of cilia that draws a vortex of water into the mouth, which the rotifer sifts for food. The food itself is ground by the trophi (jaws), located just behind the mouth in the pharynx (throat). Trophi are found in almost all rotifers, and are characteristic organs of the phylum Rotifera. The shape of the trophi determines what these animals feed on and are also a typical way of classifying them. The body is telescopic, with a semi-flexible, extendible, transparent cuticle covering. The lorica is a scleratized chitineous skeleton, which gives the rotifer its permanent shape. Interestingly, rotifers pull their corona into the lorica during death/preservation causing it to be unseen. Within the body are the stomach and reproductive organs. The final region of the rotifer body is the foot; this foot ends in a "toe" containing a cement gland with which the rotifer may attach itself to objects in the water and sift food at its leisure.
As well as their morphology
and feeding habits, reproduction in rotifers is rather unusual. Several
types of reproduction have been observed in rotifers. Some species consist
only of females that produce their daughters from unfertilized eggs, a
type of reproduction called parthenogenesis (cloning of females).
This means these parthenogenic species can develop from an unfertilized
egg, asexually. Other species produce two kinds of eggs that develop
by parthenogenesis: one kind forms females and the other kind develops
into degenerate males that cannot even feed themselves (sexual dimorphism).
These individuals copulate resulting in a fertilized egg developing within
the rotifer. The males survive long enough to produce sperm that fertilize
eggs, which then form resistant zygotes (resting eggs) that can survive
if the local water supply should dry up. When conditions are right the
eggs hatch in the water regenerating a new population.
Females carry one egg at a
time.
Crustacea
life span 50 days
Cladocera - Water Flea
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Daphnia
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Daphnia
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Daphnia
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Scientists are concerned that Daphnia lumholtzi may have negative effects on North American ecosystems. The large spines make it difficult for young fish (larval and juvenile stages) to consume this exotic. Native Daphnia have fewer, smaller spines and, therefore, are more susceptible to fish predation. The protection from predation afforded by its spines may allow Daphnia lumholtzi to replace native Daphnia species. If this replacement occurs, the amount of food available to larval and juvenile fishes may be reduced. This could result in reduced survivorship of young sport and food fishes in lakes, rivers, and fish hatcheries where Daphnia lumholtzi becomes abundant.
Copepods
life span 50 days
Cyclopoid copepodite
mini-crustacean found in both fresh and sea water
There are two forms of Copepods. One kind
swims freely and actively about, skipping in the water.
The second kind of Copepods are parasitic
crustaceans. They attach themselves to other water creatures by digging
into the flesh or scales and get their food by eating at the animals they
are attached to.
Aquatic Plants
(Native & Exotic to
Florida)
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Nutrients lead to high primary productivity,
resulting in an algae laden hypereutrophic system. Hypereutrophic
lakes are nearly impossible to repair, excess nutrients and their consequences
(organic sediments, loss of habitat, organisms and wildlife) are seldom
reverted to an oligotrophic condition.
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