Unit 2: Analysis of Habitats

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Ecological concepts

• Habitat• Environment• Population• Ecosystem• Community

Niche: Hutchinson’s n-dimensional hypervolume

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Niche: Hutchinson’s n-dimensional hypervolume

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Niche: Hutchinson’s n-dimensional hypervolume

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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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• Lithosphere– general land forms

• natural• anthropogenic

– soil types• grain size analysis (%sand, %silt, %clay + organic)• Soil Conservation Service area maps• Munsell Soil Color Charts

Macrohabitat analysis

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• Some principal land forms– Table 2A.1– coastal

• delta• coastal plain• outwash• dune• spit

Macrohabitat analysis

• reef• beach• bar• tidal flat• barrier island• swale

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• Atmosphere– measured variables

• wind: speed and direction• percent cloud cover• general weather• air temperature• relative humidity• barometric pressure

– climate

Macrohabitat analysis

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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• oligotrophic• eutrophic• mesotrophic• hypereutrophic

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Limnology: freshwater

• Lentic systems– wetlands

• 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

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

• 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

• Jackson Turbidity Unit (JTU)• nephelometer turbidity units• Formazin Attenuation Units (FAU)• Secchi disk depth

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• Color– sources

• decomposition of lignin tannins, humic acid, humates

• pollutants

– apparent color (Pt-Co units)

– true color

Physical variables in aquatic habitats

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• 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

Physical variables in aquatic habitats

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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

24-hr mean concentration Absolute minimum

Exceptional 6 mg/L 5 mg/L

High 5 mg/L 4 mg/L

Intermediate 4 mg/L 3 mg/L

Limited 3 mg/L 2 mg/L

No significant DO 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 classificationsmg/L degree of hardness0-75 soft75-150 moderately hard150-300 hard>300 very hard

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Chemical analyses

• Hardness– caused by divalent metal cations

Principal cations causing hardness

Associated anions

Ca2+ HCO3-

Mg2+ SO42-

Sr2+ Cl-

Fe2+ NO3-

Mn2+ SiO32-

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Chemical analyses

• Hardness– total hardness– calcium hardness– magnesium hardness

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• Nitrogen– role as nutrient versus pollutant

– forms• organic

• nitrate TX screening level = 2.76 mg/L• nitrite

• ammonia: TX screening = 0.17 mg/L

Chemical analyses

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• Phosphate– role as nutrient versus pollutant

– TX screening level (orthophosphate P) = 0.5 mg/L

Chemical analyses

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• 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

Chemical analyses

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Biological components

• Phytoplankton• Periphyton• Zooplankton• Nekton