Download Pond Water Analysis: Survey of Microorganisms

Science in Motion
Wilkes University
Revised 2010
Pond Water Analysis: Survey of Microorganisms
Standards:
PA ST & E Standards:
3.1.10.A1. Explain the characteristics of life common to all organisms.
3.1.10.A5. Relate life processes to sub-cellular and cellular structures to their functions.
3.1.B.A5. Relate the structure of cell organelles to their function.
3.1.10.A8. Investigate the spatial relationships of organisms’ anatomical features using specimens,
models, or computer programs.
3.1.B.A8. Recognize that systems within cells and multi-cellular organisms interact to maintain
homeostasis.
3.1.10.A9. (Science as inquiry) Know that both direct and indirect observations are used by scientists to
study the natural world and universe.
PA E & E Standards:
4.2.7.C. Use appropriate tools to analyze a freshwater environment.
4.2.10.C. Explain the relationship between water quality and the diversity of life in a freshwater
ecosystem.
Safety Notes:
1.
Do not drink the pond water; organisms can be present that can cause
dysentery(diarrhea) or intestinal infections.
2. Use dropper carefully, do not squirt water into a person’s eyes as that could cause an
eye infection.
3. Wash hands at end of lab.
4. Take care when using glass slides; if a slide breaks notify your teacher about clean
up and disposal.
Vocabulary:
1. Algae are any of various chiefly aquatic, eukaryotic, photosynthetic organisms,
ranging in size from single-celled forms to the giant kelp. Algae were once
considered to be plants but are now classified separately because they lack true
roots, stems, leaves, and embryos. Dictionary.com · The American Heritage®
Dictionary
2. Cyanobacteria are photosynthetic bacteria usually blue-green in color which are
important in certain wet ecosystems.
3. Eukaryotes are organisms whose cells have nuclei including protists, plants,
fungi, and animals.
4. Prokaryotes are unicellular organisms lacking a nucleus.
5. The kingdom Protista is composed of eukaryotes that cannot be classified as
animals, plants, or fungi. They display the greatest variety; most are unicellular, but
occasionally they can be multicellular.
6. Protozoans are “animal-like protists.” The four phyla are distinguished from one
another by their means of movement.
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Introduction:
In this exercise a study will be made of protozoans, algae, and cyanobacteria that are
found in pond water. Bottles that contain water and bottom debris from various ponds will
be available for study. Illustrations and text provided in this lab will be used to assist you in
an attempt to identify the various types of organisms encountered. Unpigmented, moving
organisms will probably be protozoans; greenish or golden brown organisms are usually
algae; and the blue-green organisms will be cyanobacteria.
To study the microorganisms of pond water it will be necessary to make wet mount
slides. The procedure for making such slides is relatively simple. The procedure is outlined
below. Remember to identify the various organisms that you encounter in the lab report.
Protozoa
The subkingdom Protozoa includes the entire animal like microorganisms of the
Kingdom Protista. All of the representatives in this subkingdom are single-celled
organisms; however, some of them do form colonial aggregates.
Externally, the cells are covered with a cell membrane, or pellicle; cell walls are
absent and distinct nuclei with nuclear membranes are present. Specialized organelles such
as contractile vacuoles, mitochondria, ribosomes, flagella, and cilia may also be present.
All protozoa reproduce asexually by cell division. Some exhibit various degrees of
sexual reproduction, called conjugation. Their ability to form cysts, which are dormant
stages, enables them to survive drought, heat and freezing.
The Subkingdom Protozoa is divided into three phyla: Sarcomastigophora,
Ciliophora and Sporozoa. The type of locomotion plays an important role in classification.
Phylum Sarcomastigophora
Members within this phylum have been -subdivided into two subphyla: Sarcodina and
Mastigophora.
Sarcodina (Amoebae)
Members of this subphylum move about by the formation of flowing protoplasmic
projections called pseudopodia. The formation of pseudopodia as commonly referred to as
amoeboid movement. Illustrations 5,6, 7 and 8 in Figure 1 are representative amoebae.
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Mastigophora (Zooflagellates)
These protozoans possess whiplike structures called flagella. There is considerable
diversity among the members of this group. Only a few representatives 1,2,3 and 4 are seen
in Figure 1.
Phylum Ciliophora
These microorganisms are undoubtedly the most advanced and structurally complex
of all protozoans. Evidence seems to indicate that they have evolved from the
zooflagellates. Movement and food- getting is accomplished with shot hairlike structures
called cilia. Illustrations 9 through 24 in Figure 1 are typical ciliates.
Phylum Sporozoa
Members of this phylum lack locomotor organelles. All are internal parasites. As
indicated by their group name, their life cycles include spore-forming stages. Plasmodium,
the malarial parasite, is the most significant pathogenic sporozoan of humans. You will
probably not usually observe this group in NE PA pond water.
Algae
Algae includes simple photosynthetic eukaryotic organisms which are either in the
Plant or Protist Kingdoms.
The algae may be unicellular, as those shown in the top row of Figure 2; colonial,
like the four in the lower right-hand comer of Figure 2; or multicellular, as those in Figure
3. The undifferentiated algal structure is often referred to as a thallus. It lacks the stem,
root, and leaf structures that result from tissue specialization.
These microorganisms are universally present where ample moisture, favorable
temperature, and sufficient sunlight exist. Although a great majority of them live
submerged in water, some grow on soil; others grow on the bark of trees or the surfaces of
rocks.
Algae have distinct, visible nuclei and chloroplasts. Chloroplasts are packets that
contain chlorophyll A and other pigments. Photosynthesis takes place within these bodies.
The size, shape, distribution, and numbers of chloroplasts vary considerably from species to
species; in some instances a single chloroplast may occupy most of the cell space.
Although there are seven divisions of algae, only five will be listed here.
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Division(Phylum)1 Euglenophyta (Euglenoids)
Illustrations 1-6 in Figure 2 are typical euglenoids, representing four different genera
within this relatively small group. All of them are flagellated and appear to be an
intermediate between the algae and protozoa. Protozoa-like characteristics see in the
euglenoids are (1) the absence of a cell wall, (2) the presence of a gullet, (3) the ability to
ingest food (not through the gullet), (4) the ability to assimilate organic substances, and (5)
the absence of chloroplasts in some species. In view of these facts, it becomes readily
apparent why many zoologists often group the euglenoids
with the zooflagellates.
The absence of a cell wall makes these protists very flexible in movement. Instead of
a cell wall they possess a semi rigid outer pellicle, which gives the organism a definite form.
Photosynthetic types contain chlorophylls A and B, and they always have a red stigma
(eyespot) which is light sensitive. Their characteristic food storage compound is a
lipopolysaccharide, paramylum.
Division (Phylum) 2 Chlorophyta (Green Algae)
The majority of algae observed in ponds will belong to this group. They are grassgreen in color, resembling the euglenoids in that they synthesize starch instead of
paramylum for food storage.
The diversity of this group is too great to explore its subdivisions in this preliminary
study; however, the small flagellated Chlamydomonas, Illustration 8 Figure 2, appears to be
the archetype of the entire group. Many colonial forms, such as Pandorina, Eudorina.
Gonium, and Volvox ( illustrations 14, 15, 19 and 20, Figure 2), consist of organisms
similar to Chlamydomonas. It is the general consensus that from this flagellated form all the
filamentous algae have evolved.
Except for Vaucheria (5) and Tribonema (6) in Figure 3, all of these filamentous
forms are Chlorophyta. All of the nonfilamentous, nonflagellated algae in Figure 4 also are
green algae.
A unique group of green algae are the desmids, see illustrations 16-20, Figure 4,
With the exception of a few species, the cells of desmids consist of two similar halves, or
semicells. The two halves usually are separated by a constriction, the isthmus.
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Division 3 Chrysophyceae (Golden Brown Algae)
This large diversified group consists of over 6000 species. They differ from the
euglenoids and green algae in that (1) food storage is in the form of oils and leucosin, a
polysaccharide, (2) chlorophylls A and C are present, and (3) fucoxanthin, a brownish
pigment, is present. It is the combination of fucoxanthin, other yellow pigments, and the
chlorophylls that cause most of these algae to appear golden brown.
Representatives are seen in figures 2, 3, and 5, Chrysococcus (12), Synura (13), and
Dinobyron(16) are typical flagellated chrysophycophytes. Vaucheria (5)and Tribonema (6)
are the only filamentous chrysophycophytes shown in figure 3.
All of the organisms in figure 5 are chysophycophytes and fall into a special
category called the diatoms. The diatoms are unique in that they have hard cells of pectin,
cellulose, or silicon that are constructed in two halves. The two halves fit together like lid
and box. It is postulated by some that our petroleum reserves were formulated by the
accumulation of oil from dead diatoms over millions of years.
Division (Phylum) 4 Phaeophyta (Brown Algae)
With the exception of three freshwater species, all algal protists of this division
exist in salt water (marine); thus, it is unlikely that you will encounter any brown algae in
this laboratory experience. All species of brown algae are multicellular and sessile. Most
seaweeds are brown algae.
Division(Phylum) 5 Pyrrophycophyta (Fire Algae)
The principal members of this division are the dinoflagellates. Since the majority of
these protists are marine, only two freshwater forms are shown in figure 2; Peridinium
(17)and Ceratium (18). Most of these protists possess cellulose walls of interlocking armor
plates, as in Ceratium. Two flagella are present: one is directed backward in swimming and
the other moves within a transverse groove. Many marine dinoflagellates are
bioluminescent.
Cyanobacteria
The blue green prokaryotic bacteria, or Cyanobacteria, comprise Division I
of the Kingdom Monera. Although these microorganisms were formerly referred to as
algae, their prokaryotic-type nucleus definitely sets them apart from the eukaryotic algae.
Although some bacteria are phototrophic, the difference between phototrophic
bacteria and cyanobacteria is that the cyanobacteria have chlorophyll a and the
phototrophic bacteria do not. Bacteriochlorophyll is the photosynthetic pigment in the
phototrophic bacteria.
Over 1000 bacteria of cyanobacteria have been reported. They are present in
almost all moist environments from the tropics to the poles, including both freshwater and
marine. Figure 6 illustrates only a random few that are most commonly seen.
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The designation of these bacteria as "blue-green" as somewhat misleading in that
many cyanobacteria are actually black, purple, red and various shades of green instead of
blue-green. The varying proportions of the numerous pigments present produce these
different colors. These pigments are chlorophyll a, carotene, xanthophylls, blue cphycocyanin, and red c-phycoerythrin. The last two pigments are unique to the
cyanobacteria.
Cellular structure is considerably different from the eukaryotic algae. As stated
earlier, nuclear membranes in cyanobacteria are absent. The nuclear material consists of
DNA granules in a more or less colorless area in the center of the cell.
Unlike the algae, the pigments of the cyanobacteria are not contained in
chloroplasts; instead, they are located in granules (phycobilisomes) that are attached to
membranes (thylakoids) that permeate the cytoplasm.
Materials:
bottles of pond water samples
droppers
6 page key
Forceps
microscope slides
cover slips
Kim wipes
miscroscope
Procedure:
1. Use forceps to remove as much filamentous algae as possible from the bottled sample
2. Make a wet mount by placing a single piece of algae, a drop of pond water, and slowly
lowering a cover slip at an angle to avoid air bubbles.
3. First observe using the lowest objective (4x), then switch to 10x or 40x to observe more
details. Reduce the lighting with the iris diaphragm. Keep the condenser high.
4. Next use a dropper to extract water (and organisms) from the bottom of the sample
bottle. Very few organisms will be found swimming around in mid-depth of the bottle.
5. Squirt water and organisms onto the middle of the slide. Avoid putting too much material
on a slide.
6. Place a cover slip over the slide.
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7. Explore the slide with a low power objective. Reduce the lighting with the iris
diaphragm. Keep the condenser high.
8.When you find an organism of interest observe and sketch in notebook or data sheet.
9. Refer to Figures 1-6 to identify the various organisms you encounter. You may not be
able to identify every organism, try your best to look through the key provided.
10. You may have more than one species on your slide.
11. You may make another slide with a new drop of pond water following the same
Procedure until the end of the lab period.
12. Complete sketches and answer the questions on the data sheet.
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