EVPP 550 Waterscape Ecology and Management

1
EVPP 550Waterscape Ecology and Management
Lecture 9

• Professor
• R. Christian Jones
• Fall 2007

2
Lake Biology OverviewHabitat Regions

• Littoral zone
• Ztotal lt zPZ
• Bottom is within photic zone
• Trophogenic PsyngtResp
• Autotrophs and heterotrophs
• Supports benthic algae, rooted macrophytes which
  add structure
• Substrate-associated plants and animals are
  characteristic

3
Lake Biology OverviewHabitat Regions

• Pelagial zone
• Ztotal gt zPZ, z lt zPZ
• Open water within photic zone
• Trophogenic PsyngtResp
• Autotrophs and heterotrophs
• Species that can suspend in water column or
  actively swim are characteristic

4
Lake Biology OverviewHabitat Regions

• Profundal zone
• Ztotal gt zPZ, z gt zPZ
• Open water and bottom below photic zone
• Tropholytic zone Resp gt Psyn
• Heterotrophs only
• both suspended and substrate associated

5
Lake Biology OverviewBiotic Communities

• Plankton
• wanderers
• Suspended in the water column
• May demonstrate limited mobility, but location
  chiefly controlled by currents
• Found principally in the pelagic region, but
  sometimes also in littoral or profundal
• Phytoplankton plant-like/photoautotrophs
• Algae, cyanobacteria
• Zooplankton animal/heterotrophs
• Rotifers, cladocera, copepods

6
Lake Biology OverviewBiotic Communities

• Benthos
• Organisms associated with the bottom sediments
• Found in both littoral and profundal
• Phytobenthos
• Includes aquatic macrophytes and benthic algae
• Zoobenthos
• Invertebrates of many groups
• Most diverse in the littoral

7
Lake Biology OverviewBiotic Communities

• Periphyton
• Attached microbial community
• slime growing on underwater surfaces
• Coats macrophytes, rocks, logs, etc.
• Includes algae, bacteria, protozoa, and
  microinvertebrates

8
Lake Biology OverviewBiotic Communities

• Nekton
• Organisms controlling their own movements
• Can move freely and inhabit all lake zones
• Includes fish and larger invertebrates

9
Lake Biology - Phytoplankton

• Characteristics
• plant component of the plankton
• Primary producers
• All have chlorophyll a
• Conduct standard photosynthesis
• H2O CO2 light ? (CH2O) O2
• All require N, P, trace elements
• Some also can utilize DOM or even may feed
  suplementally on bacteria

10
Lake Biology - Phytoplankton

• Characteristics
• Vary in taxonomy and morphology
• All divisions of eukaryotic algae represented
• Greens, diatoms, dinoflagellates, cryptophytes,
  euglenoids
• Cyanobacteria (blue-green algae) can be very
  important
• Range from very small unicells (lt1 um) to large
  colonies and filaments (up to 1 mm or more)
• Size categories 0.2-2 um picoplankton, 2-30 um
  nanoplankton, 30-200 um microplankton

11
Lake Biology - Phytoplankton

• Adaptations
• Avoid sinking
• General morphology hairs, projections, anything
  to increase friction
• Flagella can swim against gravity
• Lower density gas vacuoles, lipids
• Nutrient uptake
• Sinking breaks down boundary layer facilitation
  diffusion
• Small size higher surface area/volume

12
Lake Biology - Phytoplankton

• Adaptations
• Predation avoidance
• Colonial habitat
• Projections
• Indigestable muscilage
• Reproduction
• Mostly asexual binary fission, autocolony
  formation
• Sexual When stressed some produce zygote,
  diatoms use zygote to restore size

13
Lake Biology - Phytoplankton

• Factors affecting growth
• Light
• Light energy required for photosynthesis
• Light varies with latitude, season, time of day,
  cloud cover, attenuation coefficient, depth
• Photosynthesis shows an assumptotic relationship
  to light
• To estimate photosynthetic production in the
  field, need to account for time of day and depth
  variations in light

14
Lake Biology - Phytoplankton

• Factors affecting growth
• Light
• Photosynthetic rate/primary production quantified
  by measuring either O2 production or C-14 uptake
• Can use either
• Bottle string in situ
• P-I curve in lab extrapolated to field condition
  using light extinction and ambient light data

15
Lake Biology - Phytoplankton

• Factors affecting growth
• Nutrients
• N required for proteins, amino acids
• P required for ATP, nucleic acids
• Si for diatom frustules
• Trace metals in enzymes
• Vitamins by some algae
• Nutrients can be taken up in excess of current
  need for future use (luxury uptake)

16
Lake Biology - Phytoplankton

• Factors affecting growth
• Nutrients
• P generally limiting in most fw systems, but
  sometimes N
• Si for diatoms, Mo for N fixers
• Relationship between P and
• Cell size
• Chl a
• Pico biomass
• Group biomass

17
Lake Biology - Phytoplankton

• Factors affecting growth
• Grazing
• Spines and projections may increase effective
  size and inhibit grazing
• Cladocerans esp Daphnia are most efficient
  grazers
• Heavy grazing may reduce abundance and
  productivity of phytoplankton
• Light to moderate grazing may actually stimulate
  production by increasing nutrient availability
• Differential grazing may favor certain
  cyanobacteria and colonial green algae by
  removing their competitors since they are
  resistant to grazing
• Nanoplankton vs. Daphnia

18
Lake Biology - Phytoplankton

• Factors affecting growth
• Parasites
• Chytrid and biflagellate fungi
• Infect desmids and diatoms
• Viruses
• Can infect cyanobacteria
• Sedimentation

19
Lake Biology - Phytoplankton

• Factors affecting growth
• Washout
• Important in lakes receiving large inputs of
  water
• Mainstem reservoirs, urban lakes
• Washout processes may not be simple
• Displacement without mixing - Linear decrease in
  plankton with time
• Complete mixing exponential decline in plankton
  with time
• Washout may keep plankton low even when nutrients
  are available

20
(No Transcript)
21
(No Transcript)