Chapter 1.3 Stream Biology. There are 3 dominant groups of organisms in most stream communities....
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Transcript of Chapter 1.3 Stream Biology. There are 3 dominant groups of organisms in most stream communities....
Chapter 1.3Stream Biology
There are 3 dominant groups of organisms in most stream communities.Algae and Animal like protists InvertebratesVertebrates
• Algae
•Are plantlike protists that make their own food (autotrophs)
•Since they are autotrophs it forms the base of most aquatic food chains. •Freshwater Alage use sunlight and dissolved nutrients in a stream to make their food.
•Animal-like protists•Has many characteristics as animals
•Are aquatic organisms that eat:
•Bacteria
•Sediments that contain bacteria
•Algae
•Ex. Ameoba, Euglena
Amoeba Are protists that engulf food by flowing around and over it
Raptors Protists that eat other protist
Saprotrophs Protists that feed on decayed organic material
Invertebrates Do not have an internal skeleton made of bone
Examples of freshwater invertebrates Insects, worms, mollusks Shredders & striders
Mollusk
Mollusk
strider
VertebratesHas an internal skeleton made of bone
Examples of freshwater Vertebrates amphibians (frogs, salamanders) fish
Factors that affect Freshwater ecosystemsStream order
Smaller streams ( 1st order) flow into larger streams (2nd order) and continue on. Two streams of the same
order must come together for a stream to move up
in order.The size or order of the stream relates directly on
the organisms that are in the ecosystem. 1st order streams are home to large insect populations,
few if any fish. Plants and game fish dominate 3rd & 4th order. Larger the stream the more diverse populations of
algae, fish, and other aquatic organisms.
Factors that affect Freshwater ecosystems
TemperatureChange in temp affects the kinds and #’s of species
in a stream. Some species can live in a wide range of temps (catfish
and carp), while others species can survive only in certain temps (algae, protists and trout).
Examples of factors that causes difference in stream temp Velocity Depth Seasonal change Riparian coverage
Factors that affect Freshwater ecosystemsCurrent
UnidirectionalCauses different forces on organisms in the stream
VelocityChange in distance over time.Fish are unaffected by velocity, while insects are
generally limited to calmer water.Waters moves the fastest in the middle of the stream
below the surface.
Substrate Is the material that organisms live in, on, or around.
EX. of Organic substrate – algae, plants, mosses EX. of Inorganic substrate – rocks, sand, silt and mud
Factors that affect Freshwater ecosystems
Sunlight (plants rely on it to make food thru photosynthesis)Less sunlight = less organisms
Turbidity (clarity) Reflects the amount of suspended matter in water
Facts that affect turbidity Increase in stream erosion Increase in water volume
Heavy rain/melting snow
Factors that affect Freshwater ecosystems
Dissolved GasesOxygen and Carbon dioxide
OxygenEnters the water from the airConcentration depends mainly on temp
As temp increases, D.O. decreases
Photosynthesis also adds oxygen to the waterCurrent
As current decreases, so does D.O.
Factors that affect Freshwater ecosystems
Organic MatterMostly used for foodAlgae and detritus (particulate organic matter)Too few nutrients = loss of organismsToo many can cause mass algal blooms and then loss of
other organisms
pHScale ranges 0-14, 7 neutral, below 7 acidic, above 7
basicRainwater tends to be slightly acidicMine drainage is a major contributor to stream
acidification