Download What`s In A Watershed: Condensed Outline

Watershed Program Outline
Start Outside – Sense of Place
-Define Watershed w/ a physical example (sink, etc.)
Watershed - an "area of land that drains water, sediment, and dissolved
materials to a common outlet at some point along a stream channel" (Dunne and Leopold 1978).
-Maps of Our Watersheds – Sense of Place
US Drainages
http://worldatlas.com/webimage/countr
ys/nanewriv.gif
http://americasroof.com/river.shtml
Winyah Bay
North Inlet
Informal knowledge survey
-Why folks are here?
-What makes sense/doesn’t make sense regarding watersheds?
-What do you want to learn from this program?
Outline of program
I. Watershed Ecology
a. Physical Template (climate, HYDROLOGY, geomorphology = shaping
forces at foundation of ecosystems)
b. Biological Setting (plant/animal communities)
c. Natural Systems (how watersheds behave on different spatial and
temporal scales)
d. Watershed Structure *Activity – find your watershed*
e. Watershed Function *Activity – watershed models*
II. Agents of Watershed Change
a. The role and types of change (esp. degrading change)
b. Natural changes and ecological effects *Activity – brainstorming session*
c. Human changes and ecological effects *Activity – brainstorming session*
d. Watershed processes most vulnerable to change
III. Ways to Prevent Degrading Impacts
-Management (different scales)
-Stormwater ordinance
-BMPS
-Homeowner projects
IV. Q&A
V. Resources Handouts
Watershed Ecology
A. Physical Template (climate, HYDROLOGY, geomorphology = shaping
forces at foundation of ecosystems)
B. Biological Setting (plant/animal communities)
C. Natural Systems (how watersheds behave on different spatial and
temporal scales)
D. Watershed Structure *Activity – find your watershed*
E. Watershed Function *Activity – watershed models*
I.
Watershed Ecology
A. Physical Template (climate, Hydrology, geomorphology)
1.
The cycling of matter (which is abiotic/ non-living) creates template of air, water, and soil upon
which life can exist.
a. Hydrology
i. Water Cycle (Hydrologic Cycle)
 Solar driven
 evaporation (Evapotranspiration)
 condensation
 precipitation
 storage (runoff, infiltration)
ii. Global water budget
 Usable by people? < 1% (ground, lake/res, river)
Saltwater
% of Global Freshwater
% of Global
Water
Water
Oceans
97.542
Glaciers/Ice
1.806
Salt
0.004
Ground/Soil:
lakes/seas
Root zone
0.001
0-2500 feet
0.303
2500-12500
0.331
feet
Fresh Lakes/
0.01
Reservoirs
<0.001
Atmosphere
0.001
Rivers
<0.001
Total Salt
97.546%
Total Fresh
2.454%
 does not factor in polluted water sources
b. Different Types of watersheds created by interactions of the physical template
B. Biological Setting
1.
Basic Ecology Terms
a. Species (organism level). An organism which has certain characteristics of a given population
and is potentially capable of breeding with the same population defines a member of a species.
This definition does not apply to asexually reproducing forms of life such as Monera, Protista,
etc. Species can be considered the lowest (most specific) area of biological classification, but
lower groupings are sometimes employed (e.g., subspecies, variety, race).
b. Population. This term applies to organisms of the same species which inhabit a specific area.
c. Community. A community is an aggregate of populations of different plant and animal species
occurring within a given area.
d. Habitat. A habitat is an area where a specific animal or plant is capable of living and growing;
usually characterized by physical features, or the presence of certain animals or plants.
e. Niche. This term applies to an organism's physical location and, most importantly, functional
role (much like an occupation; what the organism specifically does) within an ecosystem.
f. Ecosystem. As defined previously, a functioning natural unit with interacting biotic and abiotic
components in a system whose boundaries are determined by the cycles and flux of energy,
materials and organisms.
 Example: Ecological Levels
Species: Cervus elaphus (Roosevelt elk)
Population: The sum total of all the elk in a given herd (e.g., migrating through the
Greater Yellowstone Ecosystem)
Community: The elk, and other populations associated with them (e.g., wolf, grizzly,
bison)
Habitat: The place where these elk live -- the open timberlands of Yellowstone NP
Niche: Primarily browses on shrubs, broadleafs, and new growth of conifers
Ecosystem: Yellowstone NP and surrounding forest, shrubland and grassland, extending
to the limit of the elk range (if we define it from the elk's perspective)
2.
Basic Ecology Concepts
a. Carrying capacity (K): This term refers to the level at which the population growth of a species
ceases. Theoretically, the term implies that a population at K has reached equilibrium with its
environment, from a resource allocation standpoint, or the maximum number of individuals the
current environment can support.
b. Competition: This term refers to two or more species or organisms which are engaged in an
active or passive struggle for resources. Intraspecific competition refers to competition within a
species (e.g., two chipmunks quarreling over a cache of acorns). Interspecific competition refers
to competition between species (e.g., a female chum salmon fighting with a female pink salmon
for access to a spawning redd).
3.
Food Webs and Trophic Ecology
a. Organizes the flow of energy into, through, and out of an ecosystem
b. Food chains intersect to create food webs
c. Trophic (feeding) levels
i. Producers (autotrophs) – photosynthetic/chemosynthetic organisms (plants, algae, bacteria,
archaea)
ii. Consumers (heterotrophs) – (primary, secondary, etc.)
iii. Decomposers – cycle nutrients back into the system
iv. Loss of energy up the Trophic Levels
 Rule of thumb:
 <1% of usable solar radiation reaching a green plant makes it past producers to
consumers.

~10% of energy is converted from trophic level to trophic level
(life/thermodynamics/etc.)
d. Keystone species
i. effect is larger than predicted by abundance
ii. effect is context dependent (not always keystone over entire range
iii. social context?
iv. oysters?, spot tail, red drum,
e. Indicator species
i. A species whose presence or absence indicates an environmental change (canaries in coal
mines)
ii. As for indicator species, there is the older use of indicator species as species that only occur
in certain types of habitats/ecosystems
iii. there is the emerging field of indicator species as quantifiers of ecosystem change or "health"
("ecosystem health" being the most loaded and ridiculous of all eco-speak).
iv. watershed examples include:
 Amphibians (freshwater): Amphibian declines, worldwide, are examples of indicators
of some people-induced global changes. Various characteristics of amphibians make
them particularly susceptible to environmental change (e.g., life both in water and on
land, porous skin, a notably omnivorous diet). Localized extinctions, extirpations, or
declines have been studied and have often shown a response to an anthropogenic
disturbance.
 Benthic macrofauna: Intolerant of poor water quality (grass shrimp?) due to increased
% imperviousness (Fred Holland’s work)
4.
Biodiversity (Genetic, Population, Species, Habitat)
a. Genetic – total # of genotypes in a given population (bottleneck of near extinctions: whooping
crane was down to 14 ind.)
b. Population – total # of populations a give species has worldwide (salmon runs: lots of salmon;
low # of runs)
c. Species – total # of species found within a given area (tropics vs. longleaf pine/salt marsh plants)
d. Habitat (Ecological) – total # of different habitats (ecotypes) within a region.
C. Natural Systems
The interactions and natural processes linking the physical template (abiotic) and biological setting
exhibit system-like behavior. The whole is greater than the sum of its parts. A watershed is more than
just a variety of natural resources coincidentally occurring in one place!
1.
Disturbance Theory
a. Change
b. Intermediate Disturbance Hypothesis
c. Few species can colonize high frequency
disturbance. Low frequency leads to a
small # of established species that keep
out colonizers
i. Disturbances
 small/frequent
 Winter Storms, longleaf stand
fires (5-7 years)
 large/infrequent (catastrophic)
 Major hurricanes, volcanos
D. Watershed Structure add in info on: watershed types/parts (estuaties, wetlands), watershed address
(flowing water, upland areas)
1.
Flowing (Lotic) Systems – diagram from http://www.epa.gov/watertrain/ecology/ecology12.html
2.
3.
a. US has more than 3.5 million miles of stream systems (including: springs, seeps, rivers, streams,
brooks, creeks, and side channels)
b. Longitudinal
i. Headwaters
ii. Transfer
iii. Depositional (Intertidal)
c. Lateral
i. Channel
ii. Floodplains (low and high)
iii. Terraces (former floodplains)
iv. Hillslopes
d. Vertical (surface/groundwater interactions)
i. Influent reaches (surface water leaks into an aquifer
ii. Effluent reaches (stream receive water from the aquifer)
e. Temporal
i. Structure is never permanent
f. Stream channel classification
Still (Lentic) Systems
a. Lakes/ponds/wetlands
b. Types of lakes
c. Wetlands ***
Upland Structure
a. Landscape pattern
i. Vegetation and Land Use
 Known to have significant impact on water condition downstream
ii. Matrix (>60%), patch, mosaic (collection of patches with no dominant matrix)
iii. Change
 Dynamic equilibrium (maintain mosaic stability w/ change)
 Evolve toward a new pattern (change overwhelms)
 Vegetation patterns
 Land use patterns (land cover is similar to natural patterns)
Activity – Find your watershed
Headwaters
Where does the water go (names of creeks, streams, rivers, bays, ocean)
boundaries
E. Watershed Function (Transport and Storage, cycling and transformation, ecological succession)
1.
Transport and Storage (of water, energy, organisms, sediments, other materials like pollution)
Activities (watershed models to discuss all this) – 30-45 minutes
a.
Transport and Storage of Water (precipitation collection and routing device)
i.
Interception (by vegetation) leads to some
ii. Evaporation
iii. Throughfall slows water for better infiltration
iv.
Saturation of soils leads to
v. Overland flow (precipitation > infiltration) causes
vi.
Drainage network development
vii.
Think of this in terms of % imperviousness
Intro CTP w/ stormwater stuff
b.
Transport and storage of sediment
i.
Inseperable from water transport/storage
ii. Erosion
iii. Deposition
iv.
Soil development
v. Channel development
 Not erosion dominated as first glance indicates
 deposition in floodplains:
 rejuvenates soil
 influence productivity/diversity of stream corridor
 contributes to plant community bank stabilization
c. pollutants
i.
water carries soluble
ii. sediment carries particulates
d. Fish/Shellfish consumption
2.
Cycling and Transformation
a. Energy and nutrient flow is cyclic, but open-ended (external input and/or output) or closed (selfcontained). Watersheds are open-ended on one scale (due to unidirectional flow) and closed on
a global scale.
b. Nutrient Spiraling
i.
Spirals among: water column, terrestrial and aquatic organisms, soil in stream corridor.
ii. Spiraling implies movement downstream and multiple exchanges between the
terrestrial/aquatic environments and the biotic/abiotic components of the watershed.
c. Biogeochemcical Cycles
i.
Decomposition
 Reduction of energy-rich organic matter (detritus), mostly by microorganisms (fungi,
bacteria, protozoa), to CO2, H2O and inorganic nutrients
 Releases nutrients for available for other organisms
 Transforms organic material into energy used by other organisms
 Watershed specifics
 Lakes – mostly occurs prior to sedimentation
 Headwater streams – external carbon sources (upland forest) are important sources of
organic material – decomposition occurs rapidly
 Bacteria/fungi modify organic material into food source for
 Invertebrate and vertebrate detritivores
 Terrestrial meets aquatic food web
 Decomposition is influenced by:
 Moisture
 Temp
 Exposure
 Type of microbial substrate
 Vegetation
 Involves following process
 Leaching of soluble compounds from dead organic matter
 Fragmentation
 Bacterial/fungal breakdown
 Consumption of bacterial/fungal organisms by other animals
 Excretion of organic and inorganic compounds
 Clustering of organic matter into larger particles
ii. Nitrogen



N2 (gaseous) is not usable by plants or most algae
N-fixing bacteria or blue-green algae convert N2 to NO2 (nitrite) or NH4 (ammonia)
Sources of N:
 N-fixing
 Precipitation
 Surface water
 Groundwater
 Losses of N
 Inorganic N ions are highly water soluble and readily leach out of soil into streams.
 Stream outflow
 Denitrification of nitrate (NO3) to N2 by bacteria
 Deposition of sediments
 Aerobic conditions (oxygen present)
 Nitrification:
 NH4+ is oxideized to NO3- (nitrate)
 Decomposition
 Primary product is NH4+ (ammonium)
iii. Phosphorus
 unpolluted watersheds
 imported through dust in precipitation
 weathering of rock
 present in extremely small amounts as:
 inorganic orthophosphate
 suspended as organic colloids
 adsorbed onto particulate organic/inorganic sediments
 in organic water
 soluble reactive phosphorus (ionic orthophosphates) is the only significant form
available to plants/algae
 is less than %5 of total P in most natural waters
 retained in aquatic systems by algae, bacteria, fungi
iv.
Nitrogen/Phosphorus limitation
 Most watershed systems are either N or P limited
 (these are the required nutrients w/ lowest availability)
 N:P ration should be ~ 15:1
 P is typically more limiting
 Slightest + in P = growth (algal bloom in aquatic settings)
 In N and P limited settings, an increase in either = eutrophication (which decreases
dissolved oxygen as plant material decomposes)
 Stream corridors often mediate upland/terrestrial nutrient exchange
 N and P in subsurface flow is picked up by riparian root systems – less in stream
(good for any already nutrient loaded waters; bad for organisms trying to eke out a
living in nutrient poor headwater streams)
d. Research at the NERR
i.
II.
SWMP/NADP
Agents of Watershed Change
The role of change
Natural changes and ecological effects
Human changes and ecological effects
Watershed processed most vulnerable to change
A.
B.
C.
D.
Change is a natural, essential feature of watersheds. Recognizing changes of concern is critical for
effective watershed management.
A.
The role of change
Change is caused by
a. Disturbance – physical/biological characteristics
b. Stress – value laden term that implies adverse effects
2.
Dynamic equilibrium
a. State of existence for ecological communities with change
i.
Change helps
 Flooding helps nutrient cycling
 Completes life cycles
b. Self-regulation mechanism of a system to deal and evolve w/ change
3.
Concept of scale
a. Change occurs over space and time
b. Determines significance of change
c. Evolutionary events and developmental processes
i.
Evolutionary events
 Extrinisic forces that create and destroy systems at a given scale
ii. Developmental processes
 Intrinsic, progressive change following system change (as a result of evo. Event)
iii. Examples
 Evo: climate change, 100 year flood
 Dev: plant succession
4.
Characterizing change
a. Source/cause
b. Effect
c. Frequency
d. Duration
1.
e. Intensity/magnitude
5.
Changes of concern
a. Change (almost) always benefits some species to the detriment of others
b. Environmental degradation
i.
Can be a subjective, value-laden concept influenced by differing ideas of desired
environmental condition (lumber, clean drinking water, wildflowers, game/fish species)
c. Degradation – adversely affects ecosystems beyond human interests/uses
i.
Reduced efficiency of nutrient cycling
ii. Changes in productivity
iii. Reversed successional sequences
iv.
Reduced species diversity
v. Changes in size distribution of species
vi.
Abundant generalists/few specialists
vii.
Increased incidence of disease
viii. Greater population fluctuations
d. Changes that produce significant (beyond cyclic change), wide-spread, and/or long-term
degradation are CHANGES OF CONCERN
i.
They alter the way an ecosystem
 Organizes
 Remains functional
 Evolves over time
 And threaten ability of communities to recover and persist after disturbance (overwhelms
dynamic equilibrium)
ii. Most often related to
 Human cause
 Cumulative effects of human plus natural agents
 Hurricane floyd (pig waste)
 Coastal housing
 Dams (have a capacity)
 Except for major evolutionary events, natural changes are not permanently degrading to
whole ecosystems
 Systems evolved with the same natural changes
 Human caused change are recent and intensive
 Not easily adapted to by systems
 = sig. / long lasting change
 many are not unavoidable***
iii. natural “disasters” can be viewed as changes of concern on a human time-scale
Activity (2 groups: natural and human-caused change. Brainstorm the: key agents of change and ecological
effects) – 15 minutes
B.
Natural changes and ecological effects
1.
Overview of a few key agents of change
a. Flooding, drought, fire, windstorms, erosion/deposition, climate change, glacial movement,
tectonic activity, volcanic eruption
b. Flooding
i.
river and stream functions
 redistribute organic material/living organisms
c.
d.
e.
f.
 exchange of sediment and nutrients w/ floodplains
 structural change (erosion/deposition)
 extreme changes (e.g. new channels)
ii. cyclic variation
 tides
 seasonal (spring thaw, fall hurricanes, winter nor’easters)
 primary selective force for organisms living in rivers and associated watersheds
 also plays role in shaping physical structure
Drought
i.
obvious – reduction of available water
ii. changes relative contribution of groundwater versus surface water and can impact
 water chemistry
 water transparency
 light regime
 temperature
iii. dry up temporary (small) water bodies
 many organisms are uniquely dependent on these water bodies (“ephemeral” waters)
iv.
upland impacts
 tree death
 crop death (ag land abandonment – think dust bowl)
 both leave unstabilized topsoil; could hurt
 water quality
 future plant communities
Fire
i.
Fire frequency/intensity depends on soil moisture, ignition, and fuel buildup
 Long intervals between fires ensures fuel buildup and corresponding > fire intensity
ii. surface fires versus crown fires
 surface – 1-10 year cycle, low intensity
 shapes community
 crown - 100-1,000 year cycle, high intensity
 opens conditions, forest succession
iii. longleaf pine
 uses surface fire to remove competition
 first 3-7 years it grows taproot instead of up
 fire resistant needles
 take advantage of nutrients post fire
iv.
impact on watersheds
 water quality
 intense fires can volatilize nutrients, making them inaccessible and sterilize soil (no
organisms)
 less intense fires create nutrient rich conditions
 large scale fires can increase erosion, runoff, and increase water temp
Erosion/sediment deposition
i.
one of the most essential processes in watersheds
 e.g. cutting off sediment supply changes erosion
ii. sediment transport depends on upland topography (source of most sediment) and stream
discharge characteristics (energy to transport sediment); more volume/gradient = more
sediment transport
Climate change (non-human caused)
i.
climate, CO2 (seen in Antarctic ice)
ii.
impacts watershed mgmt, esp. parks/wilderness areas
 climate/sea level may change so that protected areas are not the best place for current
species to thrive
g.
Glacial movement
i.
formed lakes, river valleys, mountain topography
 glacial lake missoula
h. Tectonic activity
i.
earthquakes and plate movement
i. Volcanic eruption
i.
mount st. helens
C.
Human changes and ecological effects
Closely tied to, and interactive with, natural change. One major difference is the same type of change
(from a natural perspective) occurs at a very different magnitude and/or frequency. Thresholds (of
watersheds ability to adapt to change), once crossed, limit recovery and cause loss of
resources/goods/services – to the detriment of human and ecological communities
1.
Change happens, can human caused change be bad?
a. 1999 analysis of mass biological species extinction
i.
human presence is in the top 4 sources
ii. recovery from previous extinction period did occur
 took 10 million years
2.
Overview or major human-induced changes
a. Modifications of river flow, agriculture, timber harvest, urbanization, fire suppression, mining,
harvesting fish and wildlife, introduction of exotic species, accelerated climate change
b. Modifications of River Flow (Direct modification)
i.
impoundment (dams) and withdrawal often occur simultaneously, resulting in…
 reduced flow amplitude (min/max dampened)
 increased base flow variation
 changing temps
 decreased material transport
 together this compromises stream connectivity: up and downstream and river to
floodplain
 originally - 3,500,000 free flowing river miles in US
 500-600,000 behind dams (14-17%)
 60,000 dams in US
 only 312 significant streams still free (0.4% of river mileage)
 no major rivers (annual discharge > 350 m3/sec) are unaffected by
impoundment/diversions
 dams often can be operated to closely mimic natural flow patterns (though often not)
 for more info, see
 Watershed Academy Web’s Protecting Instream Flows: How much water does a
river need?
 http://www.epa.gov/watertrain/river/
 key measures
 stabilize base downstream flow
 ensure flows necessary to transport sediment
 the Colorado’s flushing flow
 Other aspects affected by dams
 dissolved oxygen (related to water temp)
 sediment transport (dams are sediment traps – eventually silt up unless dredged)

habitat (western rivers now: cold clear water instead of warm sediment-laden water –
good for introduced trout fishing, bad for native species)
 temperature (dams release for top or bottom of reservoir?)
c. Agriculture
i.
removal of streamside vegetation and tilling of soil
ii. grazing practices
 create grassland systems dominated by inedible species
 bank erosion by livestock
 nutrient/bacteria overload into streams from animal waste
iii. irrigation practices
 diversion, detention, overuse of groundwater
 in most of US, ag is the #1 demand for water
 2/3 of global water use
 Irrigation is inefficient
 <1/2 of diverted water reaches crops
 Evaporation of reservoirs
 Seepage from canals
 Overallocated water rights (Colorado river)
 7 states + MX can withdraw more water than the river contains (annual)
 Reduce adverse effects through BMPs
 naturally vegetated stream buffers
 filter nutrients
 bank stabilization
 reduce soil loss
 moderate water temps
 helps dissolved O2
 helps fish
 terrestrial wildlife habitat
 2 challenges
 Education to inform
 resistance to change
iv.
clearing forested watersheds for crops and grazing
 degraded water quality
 modified flow regimes
 accelerated runoff
 increased erosion
 turbidity
 discharge and temp fluctuations
 compounded by soil tilling ad fertilizer/pesticide application
 even w/ crops
 less vegetated cover than indigenous vegetation
 more erosion – soil loss
 soil compaction
 ploughing (in temperate watersheds)
 in fall for spring planting
 left bare all winter during peak flow season
 of 650,000 tons of suspended sediment delivered annually to Great Lakes from
agricultural watersheds:
 0-30% from bank erosion
 70-100% are from cropland and sheet erosion
v. Increased export of dissolved nutrients (NO3 and PO4) from fertilizer and loss of forest
cover
 Increases primary production (eutrophication)
 Decreases dissolved oxygen (via decomp.)
vi.
Toxins from pesticides (organochlorine compounds)
 DDT, banned in 1972, still found in trace amounts in soil, sediment, and tissue samples
from ag. watersheds in US
d. Timber harvest
i.
many impacts similar to ag impacts
ii. loss of vegetation
 increases peak stream flow
 compounded by road construction
 permanent bare surface
 compact soil
 reduced infiltration
 increased surface runoff
 + erosion/siltation
 fragments habitat
 stream crossings can block fish
 higher base/peak flow fluctuations
iii. impacts watershed level processes
 onsite BMPs alone don’t work (buffers)
 need integrated watershed analysis
e. Urbanization (% imperviousness)
i.
one of the most severe impacts on watershed
 not just clearing; paving
ii. increases surface runoff
 earlier and higher peak flows (after storms)
iii. + flooding frequency
iv.
compounded by storm sewers/channelization/bank armoring
 intended as flood control
 often leads to downstream flooding
 increases flow velocity and volume
v. Contaminants
 Point source (sewage, industry)
 Non point source (storm runoff, acid rain)
 small volume but everywhere
 = big input of pollution
 assessment and control are difficult
vi.
relationship between % imp and diversity of stream communities
 start to see impact @ 12%
 severe degradation @ 30%
 BMPs (i.e. buffers can help)
vii.
urbanized impacts spread far beyond urban area
 drinking water sources from afar
 e.g. LA, NYC
 where do we get our water?
f. Fire suppression
i.
leads to:



+ fuel accumulation
increase in shade tolerant species
decrease in fire dependent species (conifers)
 longleaf pine
ii. most impact in areas of frequent fire regimes
iii. changes cause
 + in potential for high-intensity crown fires
 exceed our control
 kills all species present
iv.
fire is important part of forest ecology
 now mgmt. of forest in Nat’l parks combines
 let burn aproach
 prescribed burns
 allowed burns threaten timber availability over the long-term
 resource use (timber, recreation, aesthetics) versus preservation of ecological processes
(watersheds)
g.
Mining
i.
Historically, mining = severe, long-term impacts
 Restoration is still a challenge
ii. stages of mining
 preliminary and advanced exploration
 mining and milling
 smelting and refining
 mine closure
iii. a mine site is only one spot in a large web of activity, transportation routes, and infrastructure
iv.
impacts
 removal of soil and rock
 ~24 billion tons (non-fuel) minerals worldwide, annually
 + overburden (material above the ore) = 28 billion tons
 this is 1.7 times the sediment in all world’s rivers
 even if inert, lots of erosion causes siltation
 waste rock
 stored above ground
 valley fill
 sulfide minerals react with water and O2 to create sulfuric acid
 water leaches this out to form
 AMD: acid mine drainage
 Can take 100s-1000s of years
 Extraction of ore and disposal of tailings
 90% of ore ends up as tailings (residue from ore concentration)
 Dumped into piles or ponds near the mine
 Contain toxins used as ore concentrators
 Toluene
 Tailing combine to make new metals (heavy metals)
 Arsenic
 Cadmium
 Copper
 Lead
 Zinc
h.
Harvesting fish and wildlife (commercial and recreational)
i.
impacts beyond removal of target species
 community composition
 trophic interactions
 esp. from commercial pressure
 shift from large, long-lived, high trophic level species to
 small, short-lived, planktivorous/insectivorous species
 can cause a trophic cascade
 decrease of high levels (fish eaters) changes the regulation of lower level
(planktivorous) species, which impacts the zooplankton composition, which
determines the phytoplankton that compete for any nutrients
ii. mgmt: on example-moratoriums on specific species
 type of sacrifice that might be necessary
 often needs habitat restoration also
i. Introduction of exotic species
i.
human mobility increases species mobility
 intentionally
 ornamental plants
 popular game species (fish)
 unintentionally (hitchhiker seeds)
 zebra mussels
 abundant in great lakes, came in ship ballast water from Europe
 invasive riparian plants spread along river corridors
 roadside plants
 introduced species do not always become invasive (outcompete native species), but often
do, due to
 prolific reproduction strategies
 lack of natural predators
 changes food webs, habitat
 70% of 20th century’s extinctions were related to exotic invasives
ii. local examples
 beach vitex (int.)
 phragmites (unint.)
j. Accelerated climate change
i.
major difference from natural climate change = rate
 CO2 (a greenhouse gas) illustrates this trend
 since 1860: from 280ppm to 360ppm
 ice cores from 160,000 years ago show that global temp is closely tied to CO2 levels
 if current trends continue, +3.5 F over next century
 last century we warmed 1.0 F
 warming hits poles more than equator
 Cretaceous period was 8.5 F warmer than today
 Small increases = major impacts
 an increase of air temp by 1 F = 6% more water carrying capacity
 warming increases water cycle
 longer droughts/heavier rains
Potential Climate Change Impacts
Climate Changes
Weather-related Mortality
Health Impacts
Temperature
Infectious Disease
Agriculture Impacts
Precipitation
Forest Impacts
Water Resource Impacts
Sea Level Rise
Impacts on Coastal Areas
Species and Natural Areas
D.
Air Quality-Respiratory Illness
Crop Yields
Irrigation Demands
Species Composition
Shift in geographic range of forests
Forest Productivity
Changes in Water Supply
Water Quality
Increased Competition for Water
Erosion of Beaches
Inundate Coastal Lands
Costs to Defend Coastal
Communities
Shift in Ecological Zones
Loss of Habitat and Species
Watershed processes most vulnerable to change
1.
How change affects watersheds
a. Result of several agents acting together
b. Changes of concern often a natural/human agents combo
c. Changes is multiple steps
i.
original disturbance = direct effects
 additional indirect effects
d. interactive effects
i.
two or more agents produce impacts more severe than their individual effects
 examples:
 climate change/+ fire/ plant species
 pH and metals (at critical pH levels, metals precipitate out and become available to
the food chain)
e. threshold levels
i.
environmental change proceeds past a certain level, it often results in a change of state at
which previous relationship no longer hold true and new influences arise
 example
 eutrophication: + algal production may cause + productivity in zooplankton and
planktivorous fishes. At a certain level of algal production, the relationship ends.
Superabundance of algal cells means abundance of algal cell death and
decomposition before they can be eaten. This + oxygen demand may mean –
productivity of higher trophic levels.
2.
Most Vulnerable Processes
a.
b.
c.
d.
Hydrology
Sediment Transport
Nutrient Cycling
Trophic Interactions/Competition
a.
Hydrology
Vegetation Removal by Land Use
Practices:
Forestry, Agriculture, Urbanization
Evapotranspiration (-); Infiltration (-);
Surface Runoff (+)
Frequency and Magnitude of High
Stream Discharge (++)
More/Higher Floods
Reduced Groundweter Discharge
Bank Erosion
Lower Base Flows
Sedimentation
Reduced Aesthetics
Degraded Stream Habitat
Increased Maintenance Costs
Property Loss and Damage
Loss of Fish and Invertebrates
These effects are often exacerbated by
measures designed to mitigate flooding
and erosion
Further increases flooding and
downstream erosion
Urban and logged streams tend to be:
wider, warmer, and more turbid
b.
High intensity floods beyond ability of
fish and inverts to adapt
Sediment Transport
i.
erosion and sedimentation increase due to typical land use practices
 streams are characterized by increased:
 turbidity
 uniform substrates
 suspended fine particles
 impacts aquatic species
 suspended sediment clogs gills
 fine sediment clogs spawning beds
 increased siltation often includes contaminants
 dams/impoundments/diversions
 decreased flow = decreased sediment transport
 no deposition downstream
 more erosion
 impacts habitat
c. Nutrient Cycling
i.
human activities tend to:
 remove nutrients (ag/timber) from soil
 = loss of nutrients
 transport to cities (food/wood products)
 ultimately load nutrients to other watersheds (sewage)
 = excess nutrient loading
 sewage contains high Nitrogen (NO3) and Phosphorus (PO4)
 can lead to eutrophication
 replacing lost nutrients (fertilizers)
 easily washes off and into water
 worsens eutrophication
ii. Nitrogen input (atmosphere, soil, water) has doubled due to human activities
 Atmosphere
 Combustion of fossil fuels =
 N2O (greenhouse gas)
 other oxides of nitrogen (eg NO)
 smog producer
 soil input
 fertilizers and atmospheric deposition
 water
 fertilizer runoff
 direct input (sewage)
 NH4 builds in soils, converted to NO3 (microbial activity)
 releases H and acidifies soil
 neg (-) NO3 leaches to water
 carries positive charged nutrients (calcium, magnesium, potassium)
 loss from soil
 degrades soil
 acidification
 removal of + cations
 water has eutrophication problems
d. Trophic Interactions/Competition
i.
Direct impacts from
 harvest of species
 introduced exotic species
ii. Indirect impacts
 Habitat alteration
iii. human impact, in general
 favors generalists that can tolerate a wide variety of conditions
 causes a decline in sensitive or specialized species
 also tends to impacts high trophic levels
 harvest of top level predators
 bioaccumulation
 PCBs in a top predator can be 25 million times the concentration in the
surrounding water
3.
Summary of change
a. Unavoidable and essential
b. Occurs at varying space and time scales
c. Characterized by frequency/intensity
d. Changes of concern =
i.
long term sig change
ii. loss of primary watershed processes/structure
e. natural agents of change
i.
climate
ii. glacial
iii. tectonic
iv.
volcanic
v. drought/flood
vi.
fire
vii.
windstorms
viii. erosion/sedimentation
ix. disease outbreaks
f. human-made agents of change
i.
accelerated climate change
ii. timber harvest
iii. agriculture
iv.
urbanization
v. modification of river flow
vi.
mining
vii.
fire suppression
viii. fish/wildlife harvesting
ix. exotic species introduction
x. air pollution
g.
watershed changes are often a combo of agents, both cumulative and interactive
h. changes of concern often result from interactions of natural and human agents
III.
Ways to mitigate, reduce, and eliminate the impact of change
A.
Different scales
1.
Watershed (regional) mgmt
2.
local/municipal mgmt
3.
site specific mgmt (homeowner)
a.
B.
BMPs
C.
G’town stormwater ordinance
IV.
Q and A
V.
Resources
 Flyer
 Resource handout (include glossary of watershed terms)
REFERENCES
-US EPA’s Watershed Academy Web: http://www.epa.gov/watertrain
Introduction to Watershed Ecology (Thomas O’Keefe, Scott Elliott, Robert Naiman-UW; Douglas
Norton-EPA Office of Water)
Agents of Watershed Change (Thomas O’Keefe, James Helfield, Robert Naiman-UW)
Images taken from those documents unless otherwise noted…