Unit 2: Analysis of Habitats
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Ecological concepts
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Habitat
Environment
Population
Ecosystem
Community
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Niche: Hutchinson’s n-dimensional hypervolume
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b
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Niche: Hutchinson’s n-dimensional hypervolume
c
a
b
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Niche: Hutchinson’s n-dimensional hypervolume
d
c
a
b
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Habitat
• Macrohabitat
• Microhabitat
• Habitat dimensions
– atmosphere
– lithosphere
– hydrosphere
– biosphere
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Macrohabitat analysis
• Temporal information
– date
– time
– observers’ names
• Spatial information
– specific location, GPS coordinates
– topography
– drainage characteristics, watershed area
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Macrohabitat analysis
• Lithosphere
– general land forms
• natural
• anthropogenic
– soil types
• grain size analysis (%sand, %silt, %clay + organic)
• Soil Conservation Service area maps
• Munsell Soil Color Charts
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Macrohabitat analysis
• Some principal land forms
– Table 2A.1
– coastal
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delta
coastal plain
outwash
dune
spit
• reef
• beach
• bar
• tidal flat
• barrier island
• swale
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Macrohabitat analysis
• Atmosphere
– measured variables
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wind: speed and direction
percent cloud cover
general weather
air temperature
relative humidity
barometric pressure
– climate
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Macrohabitat analysis
• Community type
• Zonation: horizontal patterns
• Stratification: vertical patterns
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Stratification
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Stratification
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Macrohabitat analysis
• Habitat diversity
– habitat richness: number of different
habitats present
– habitat heterogeneity versus dominance
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Analysis of aquatic habitats
• Habitat type
– marine
– estuarine
– freshwater
• Communities based on salinity gradients
– euryhaline
– stenohaline
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Limnology: freshwater
• Lentic systems
– calm, slow or non-moving
– lakes and ponds
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oligotrophic
eutrophic
mesotrophic
hypereutrophic
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Limnology: freshwater
• Lentic systems
– wetlands
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marsh
swamp or slough
bog
pothole or playa lake
bottomland hardwood
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Limnology: freshwater
• Lentic systems
– zonation
• littoral zone (shallow, shoreline)
• open water
– euphotic zone
– compensation depth
– aphotic zone
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Limnology: freshwater
• Lotic systems
– moving
– rivers, streams, creeks, bayous
– riparian habitats
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Water use categories
• Aquatic life
– parameters designed to protect aquatic
species
– e.g., dissolved oxygen, nutrients, toxics
• Contact recreation
– relative risk to humans from swimming and
other water sports
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Water use categories
• Public water supply
– indicators used to evaluate water source for
public water systems
– e.g., nutrients, toxics
• Fish consumption
– indicators for fish health or disease
– toxic chemicals contained in fish tissue
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Water quality standards
• Used by EPA / TCEQ to evaluate condition
of water and establish limits on permitted
dischargers
• Numeric standards
– values specific to segments
• Narrative standards
– protect aesthetics and designated uses
– overall screening limits
– not segment specific
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Physical variables in aquatic habitats
• Water temperature
– temperature profile
– temperature stratification
• epilimnion / hypolimnion
• thermocline
– biological effects
• reaction rates
• migration / reproductive cues
• physiological tolerances
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Physical variables in aquatic habitats
• Turbidity
– light scatter or penetration in water
– dependent on
• dissolved chemicals
• suspended particulates
• microbes and algae
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Physical variables in aquatic habitats
• Turbidity
– sources
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colloidal rock particles
eroded soil
domestic and industrial wastewater
street washings
– environmental significance
• aesthetics
• photosynthesis
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Physical variables in aquatic habitats
• Turbidity
– measurement
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Jackson Turbidity Unit (JTU)
nephelometer turbidity units
Formazin Attenuation Units (FAU)
Secchi disk depth
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Physical variables in aquatic habitats
• Color
– sources
• decomposition of lignin  tannins, humic acid,
humates
• pollutants
– apparent color (Pt-Co units)
– true color
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Physical variables in aquatic habitats
• Conductivity (specific conductance)
– measure of how well water can conduct an
electrical current
– dependent on ion concentration in water
– indirect measure of salinity and other salts
– measured in mmhos, µmhos, mS, µS
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Chemical analyses
• Dissolved oxygen (DO)
– essential for life processes of most aquatic
organisms
– low DO often results from high organic
matter loads or low flow
– excessive DO often results from excess plant
production
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Chemical analyses
• Dissolved oxygen (DO)
– DO in warm water versus cold water
– effect of salinity
– percent saturation
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Chemical analyses
• Dissolved oxygen (DO)
– State of Texas Surface Water Quality
Standards for DO
Exceptional
High
Intermediate
Limited
No significant DO
24-hr mean concentration
6 mg/L
5 mg/L
4 mg/L
3 mg/L
2 mg/L
Absolute minimum
5 mg/L
4 mg/L
3 mg/L
2 mg/L
1.5 mg/L
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Chemical analyses
• pH
– general indicator of water quality in neutral
range (pH 6-8.5)
– major factor affecting most chemical and
biological reactions
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Chemical analyses
• Alkalinity and CO2
– measure of buffering capacity of water
– sources of alkalinity
• hydroxides
• carbonates
• bicarbonates
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Chemical analyses
• Hardness
– geographic variation in natural water
hardness
– hardness classifications
mg/L
0-75
75-150
150-300
>300
degree of hardness
soft
moderately hard
hard
very hard
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Chemical analyses
• Hardness
– caused by divalent metal cations
Principal cations
causing hardness
Ca2+
Mg2+
Sr2+
Fe2+
Mn2+
Associated
anions
HCO3SO42ClNO3SiO3242
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Chemical analyses
• Hardness
– total hardness
– calcium hardness
– magnesium hardness
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Chemical analyses
• Nitrogen
– role as nutrient versus pollutant
– forms
• organic
• nitrate
• nitrite
TX screening level = 2.76 mg/L
• ammonia: TX screening = 0.17 mg/L
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Chemical analyses
• Phosphate
– role as nutrient versus pollutant
– TX screening level (orthophosphate P) =
0.5 mg/L
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Chemical analyses
• Other water chemistry parameters
– trace metals / sulfate / tannins and lignins
– gases: carbon dioxide, hydrogen sulfide
– BOD
• measure of oxygen demanding bacterial
composition of water
• measures oxygen consumption by aerobic
microorganisms as they decompose organic
material present in water
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Biological components
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Phytoplankton
Periphyton
Zooplankton
Nekton
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