Aquatic Ecology
Objectives
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Discuss biodiversity and endangered species.
Examine the needs of all aquatic environments.
Discuss the three types of aquatic environments.
Identify various zones in a lake.
Analyze the trophic stages of a pond, lake, or
stream.
Discuss and define biological indicators.
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List sensitive and tolerant groups.
Describe how to collect samples.
Identify macro invertebrates in your sample.
Identify and determine the quality of a local stream.
BIODIVERSITY PROTECTION
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Hunting and Fishing Laws
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By 1890’s, most states had enacted some hunting and
fishing laws.
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General idea was pragmatic, not aesthetic or moral
preservation.
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White-tailed deer
Wild turkeys
Wood ducks
Endangered Species Act
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Established in 1973.
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Endangered are those considered in imminent danger of
extinction.
Threatened are those likely to become endangered, at
least locally, in the near future.
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Vulnerable are those that are naturally rare or have been
locally depleted to a level that puts them at risk.
Endangered Species Act Cont’d
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ESA regulates a wide range of activities involving
Endangered Species:
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Taking (harassing, harming, pursuing, hunting, shooting,
killing, capturing, or collecting) either accidentally, or on
purpose.
Selling
Importing into or Exporting out of the U.S.
Possessing
Transporting or Shipping
Endangered Species Act Cont’d
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Currently, the U.S. has 1,300 species on its
endangered and threatened lists, and 250 candidate
species waiting for consideration.
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Number reflects more about human interests than actual
status.
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Invertebrates make up 75% of all species, but only 9%
worthy of protection.
Listing process is extremely slow.
Recovery Plans
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Once a species is listed, USFWS is required to
propose a recovery plan detailing the rebuilding of
the species to sustainable levels.
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Total cost of all current plans = $5 billion.
Opponents have continually tried to require
economic costs and benefits be incorporated into
planning.
Reauthorizing ESA
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ESA officially expired in 1992.
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Proposals for new ESA generally fall into two general categories:
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Versions that encourage ecosystem and habitat protection rather than
individual species.
Safe Harbor policies that allow exceptions to critical habitat
designations.
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(Economic Considerations)
What are the basic needs of
aquatic biota?
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CO2
O2
Sunlight
Nutrients- food &
minerals
What factors influence the
availability of those basic
needs?
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Substances dissolved in
water- Nitrates,
phosphates, potassium, O2
Suspended matter- (silt,
algae) can affect light
penetration
Depth
Temperature
Rate of flow
Bottom characteristics
(muddy, sandy, or rocky)
Internal convection currents
Connection to or isolation
from other aquatic
ecosystems.
Types of Aquatic Ecosystems
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Freshwater Ecosystems
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Transitional
Communities
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Standing Water- lakes &
ponds
Moving Water- rivers &
streams
Estuaries
Wetlands- bogs/fens,
swamps, marshes
Marine Ecosystems
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Shorelines
Barrier Islands
Coral Reefs
Open Ocean
Types of Aquatic Systems
Rivers &
Streams
Lakes &
Ponds
Wetlands
Estuaries
Groundwater
Marine system
Freshwater Ecosystems
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Usually 0.005% salt
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Some exceptions:
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Great Salt Lakes-
5-27%
salt
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Dead Sea- 30% salt
Moving water- high
elevations; cold; high O2;
trout; streamlined plants
Standing water- lower
elevations; warmer; less
O2; bass, amphibians;
cattails, rushes
Lentic Zones
Lotic Environments
Lotic Environments
Lakes and Ponds
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Critical differences from
other freshwater
systems
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Longer residence time
Typically not shaded
with most of the
surface area exposed
to sunlight
Florida lakes are
typically shallow and
well mixed
Florida lakes are often
highly colored, but can
have light reaching
much of the bottom
Photo by Bill Wade
Watershed / Lake Area Ratio
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Watershed area
relative to lake area
will influence the
residence time of water
in the lake.
This ratio is also a
factor in the nutrient
loading to the lake
Lake Habitat Zones
Lake Littoral Zone
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Functions
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Intercepts Nutrients
Refuge from Predators
Nursery for Fish
Eutrophic Southern Lake
Oligotrophic Northern Lake
Lake Limnetic/Pelagic Zone
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Functions
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Plankton
Zooplankton
Lake Limnetic / Pelagic Zone
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Submerged Aquatic Vegetation (SAV)
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Nutrient uptake
Sediment stabilization
Habitat
Oxygen production
Pond Food Web
Algae/Plants
Fish
Nutrients
Grazers
Nutrients
Algae/Plants
Grazers
Fish
Relationship Between Nutrients and
Pond Productivity
Nutrients
Nutrients
Nutrients
Nutrients
Algae/Plants
Grazers
Algae/Plants
Algae/Plants
Grazers
Grazers
Algae/Plants
Nutrients Algae/Plants
Grazers
Grazers
Fish
Fish
Fish
Fish
Fish
Habitat/Environmental Impacts
Low nutrients
Low primary productivity
Low grazers and insects
Low fish production
Clear water
Sandy/low organic matter on bottom
Moderate
nutrients
TROPHIC
STATE
Increased primary productivity
More grazers and insects
More fish production
Moderate water clarity
More aquatic plants
Some organic sediment accumulation
HighTROPHIC
nutrients STATE
High primary productivity
Large number of grazers and insects
Moderate fish production
Low water clarity, or
Clear with aquatic plants
High organic sediment accumulation
Trophic State Change
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Nutrients & Productivity
Sediment &
Accumulation
Species Shifts
Species Richness
How is a lake stratified and
what lives in each level?
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Epilimnion- upper layer of
warm water; high light & O2;
ex: water striders, phyto- &
zooplankton, fish
Thermocline
(mesolimnion); middle
layer; medium light & O2;
ex: phyto- & zooplankton,
fish
Hypolimnion- lower layer
of cold water; lower light &
O2; ex: fish
Benthos- bottom level; no
light & little O2; ex:
anaerobic bacteria,
leeches; insect larvae
Littoral- near the shoreline;
cattails, rushes,
amphibians, etc.
Transitional Communities
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ESTUARIES
Where freshwater
dumps into ocean
Brackish (less salty
than seawater)
Has rich sediments
that often form deltas
Productive &
biodiverse
Organisms adapted to
varying levels of
salinity as tide ebbs &
flows
“Nursery” for larval
forms of many aquatic
species of commercial
Transitional Communities
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WETLANDS
Land saturated at least part of
the year
Swamps- have trees like bald
cypress; high productivity
Marshes- no trees; tall
grasses; high productivity
Bogs/Fens- may or may not
have trees; waterlogged soil
with lots of peat; low
productivity
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Swamp
Marsh
Fens- fed by groundwater &
surface runoff
Bogs- fed by precipitation
Bog
Fen
Importance of Wetlands
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Highly productive- get lots of
sunlight, ↑ plants = ↑ animals
Nesting, breeding ground for
migratory birds
Slows flooding by absorbing runoff
Silt settles, making water clearer &
nutrient rich
Trap & filter water
Natural chemical rxns neutralize
and detoxify pollutants
Gives H2O time to percolate thru
soil & replenish underground
aquifers.
Threats- artificial eutrophication
(see slide 13), draining,
sedimentation via construction
“Nature’s Septic Tank”
Marine Ecosystems
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SHORELINES
Rocky coasts- great density &
diversity attached to solid
rock surface
Sandy beaches- burrowing
animals
Threats- due to hotels,
restaurants, homes on beach,
more plant life destroyed,
destabilizing soil, susceptible
to wind & water erosion
Insurance high; danger of
hurricanes, erosion
Build sea walls to protect
people but changes &
endangers shoreline habitat
Marine Ecosystems
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BARRIER ISLANDS
Low, narrow offshore
islands
Protect inland shores
from storms
Beauty attracts
developers =
developers destroy
land
New coastal zoning
laws protect future
development
MARINE ECOSYSTEMS
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CORAL REEFS
Clear, warm shallow seas
Made up of accumulated
calcareous (made of
calcium) skeletons of coral
animals
Formation depends on light
penetration.
Have a symbiotic
relationship with algae
Very diverse, abundant
(rainforests of sea)
Threats- destructive fishing
(cyanide & dynamite to stun
fish), pet trade; about 3/4ths
have been destroyed
What factors can alter
aquatic ecosystems?
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Natural Successionnormal cycle of pond
becoming forest
Artificial Successionhumans add N & P
to water via fertilizer
& sewage causing
succession to
happen faster =
EUTROPHICATION
What factors can alter
aquatic ecosystems?
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Humans!
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Find food
Recreation
Waste disposal
Cooling of power
plants
Transportation
Dams, canals
Algae and Microinvertebrates
Can’t be seen with the naked eye
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Cyanophyta
Chlorophyta
Euglenophyta
Heterokontophyta
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Xanthophyceae
Chrysophyceae
Bacillariophyceae
Phaeophyceae
Oomycetes
Rhodophyta
Pyrrhophyta
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Rotifera
Ectoprocta/Bryozoa
Arthropoda
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Crustacea
(superclass)
 Cladocera
(suborder)
 Copepoda (order)
Chelicerata
(subphylum)
 Arachnida
(superclass)
 Acari (order)
Phytoplankton
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Phytoplankton – microscopic plants and some types of
bacteria which obtain their energy via photosynthesis.
Important to the ecosystem because
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Part of the primary producing community
Assist in recycling elements such as carbon and sulfur which
are required elsewhere in the community.
Phytoplankton
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Basis for aquatic food chain b/c major primary
producers
Huge impact on global primary production
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Estimated at 105 – 106 g C/year
More abundant in well-lighted areas with higher
temperatures
Relatively unspecialized physiology, but are
evolved to maintain buoyancy
Very little competitive exclusion
May be unicellular or multicellular
Phytoplankton
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Asexual reproduction keep numbers high
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Cyanobacteria can double several times/day
Diatoms are slower, but can double every 1-2 weeks
Phytoplankton
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Phylogenetically diverse
Important groups:
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cyanobacteria
dinoflagellates
euglenoids
green algae
diatoms
Diatoms: Order Centrales
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Characterized by
centric and often
circular form
Note also the
numerous punctae
(pores)
Diatoms
Gyrosigma obtusatum
Pleurosira laevis
Nitzschia levidensis
Dinoflagellates
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Phylum Pyrrhophyta
“Whirling flagella”
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Habitat: Mostly
marine, some
freshwater
Notes:
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Unicellular protists
2 dissimilar flagella
Many are
photosynthetic
Dinoflagellates
Notes:
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Heterotrophic
dinoflag feed on
diatoms or other
protists
Marine “blooms”
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Red tides
Rotifers
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Phylum Rotifera
“Rotating wheel”
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Habitat: Fresh water
Notes:
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Heterotrophic
Corona of cilia provide
movement and means
to move food toward
the mouth.
Rotifers
Notes:
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Sessile, anchors itself
with foot
May enter dormancy
and form cyst when
env. conditions
unfavorable
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Cysts last up to 50
years
Bryozoa
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Phylum Ectoprocta
(=Bryozoa)
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“Moss animals”
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Habitat: Marine and
both lotic/lentic
freshwaters
Notes:
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Sessile; can be
epiphytic, epilithic or
epidendric
Colonial; a number of
clones inhabit one
structure
Extend ciliated tentacles
to filter food from water
Often host a number of
smaller organisms
Bryozoa
Cladocera
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Phylum Arthropoda, Superclass
Crustacea, Suborder Cladocera
Water fleas or Daphnia
Habitat: widespread; very
important in lentic habitats
Notes:
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Uses antennae to swim
Many populations react to
diurnal cycles, making vertical
migrations each day
May be predacious or
herbivorous
Head varies considerably
from rounded to hooded but
eye spot is always distinctive
Body laterally compressed
Cladocera
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Notes
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Parthenogenetic:
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most eggs are diploid
females (asexual
repro)
occasional diploid
males fertilize haploid
eggs produced by
females for sexual
reproduction
Copepods
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Phylum Arthropoda,
Superclass Crustacea,
Order Copepoda
Habitat: widespread in
marine and fw; may be
benthic or pelagic
Notes:
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may be parasitic,
predacious or detrivorous
often seen carrying egg
sacs on both sides
develop through several
stages as immature
copepods before reaching
maturity
Characterized by
conspicuous 1st pair of
antennae and single
anterior eye
Acari (Water Mites)
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Phylum Arthropoda,
Subphylum Chelicerata,
Superclass Arachnida,
Order Acari
Habitat: most abundant
in lotic waters
Notes:
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Have 6 legs when
young, 8 when mature
Many are parasitic but a
few are predaceous
Possess no antennae
Related to terrestrial
spiders
Macroinvertebrates
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Show bioindicators pdf.