QUIZ #8
1. Draw the IDH curve. When and why is species diversity
highest according to IDH?
2. Explain how anthropogenic disturbance can be either
beneficial or detrimental.
3. How can wetlands function as a transitional community
(zone) between open lakes and upland terrestrial forest
habitats?
4. What is the difference between (or define, up to you)
allogenic and autogenic succession.
5. Give an example of both primary and secondary
succession.
PRIMARY PRODUCTIVITY
RANGE OF PRODUCTIVITY:
CLIMATE AND LOCAL ENVIRONMENTAL VARIABLES
SECONDARY PRODUCTIVITY
PLANT AND ANIMAL ADAPTATION
Forces leading to adaptation
1.
2.
3.
4.
Anoxia: lack of oxygen
Salinity: fluctuating or high salinity
Soil toxins: sulfide, methane, etc.
Nutrient stress: low nitrogen or phosphorus
availability
5. Submergence: anchorage, locomotion, change in C
source, wave energy, light
6. Herbivory/Predation
Responses to anoxia at different levels of complexity
Bacteria
• alternative respiratory pathways
• utilize energy in reduced compounds (e.g. NH4+, CH4, S-)
Plants
• arenchymous tissue (ethylene production), lenticels,
adventitious roots, stem elongation, shallow rooting,
hypertrophy, carbohydrate storage structures
• pressurized gas flow, radial oxygen loss
• Alcohol dehydrogenase(ADH) accumulation
Animals
• specialized respiratory structures (gills, parapodia, etc.)
• pigments
• various other physiological and behavioral modifications
Responses salt stress at
different levels of complexity
Bacteria
• accumulation of “non-lethal” ions (e.g. K+ relative to Na+)
• compatible (organic) solutes
Plants
• salt exclusion
• salt excretion
• storage in vacuoles or senescent tissues
• C4 instead of C3 photosynthetic pathway
Animals
• osmoregulate
• osmoconform
OXYGEN STRESS:
ANAEROBIC RESPIRATION
OXYGEN PUMPING
Illustration of gas flow
in the water lily
Pressurized gas flow is a function of water depth
FLOODING
TOLERANCE
Loblolly pine root
Flooded vs. Nonflooded and
ethylene production
Loblolly pine seedling stem
Mangrove Adaptations
waxy leaves and
viviparous seedlings
lenticels
specialized root
structures
salt exclusion vs. salt excretion
Mangroves are better
competitors
in salty environments
NH4+ uptake
SOIL PHYTOTOXINS:
IMPACT NUTRIENT UPTAKE
Vmax
Km NH4+ concentration
EFFECTS OF
POREWATER
SALINITY
NH4+ uptake
Vmax
Km NH4+ concentration
Spatial Gradients
High tide
low tide
increasing soil salinity, and sulfide concentrations
decreasing soil redox
Reciprocal effects of vegetation on soil
SALT MARSH COMMUNITY STRUCTURE
PHOTOSYNTHETIC
PATHWAYS
C3 PATHWAY
C4 PATHWAY
Stomata imprints on underside of red mangrove leaf
Measuring photosynthesis and transpiration in a mangrove forest
Definitions
tolerator (conformer): an organism that has functional
modifications allowing it to survive and often function in the
presence of stress.
regulator: organisms that actively avoid stress or modify it to
minimize its effects (e.g. thermoregulator, osmoregulator, etc.)
SALT STRESS IN ANIMALS
Reptilian tolerance to anoxia
NEKTON ADAPTATIONS
Estuarine-dependent life cycles
Brown shrimp
Gulf menhaden
Seasonal occurrence of
estuarine-dependent
species
Quiz # 8
1. Why is nitrogen fixation inhibited by aerobic conditions?
2. Describe one way in which bacteria deal with anoxia.
3. Describe a mechanism that allows hydrophytes to deal with
salinity stress.
4. What is the source of inorganic carbon for plants
photosynthesizing under water (i.e., SAV)?
5. What microbial process gives rise to reduced inorganic
nitrogen?