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. Anoxia: lack of oxygen2. Salinity: fluctuating or high salinity3. Soil toxins: sulfide, methane, etc.4. Nutrient stress: low nitrogen or phosphorus

availability5. Submergence: anchorage, locomotion, change in C

source, wave energy, light6. 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 atdifferent 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

FLOODINGTOLERANCE

Flooded vs. Non-flooded and

ethylene production

Loblolly pine root

Loblolly pine seedling stem

Mangrove Adaptations

waxy leaves andviviparous seedlings

lenticelsspecialized root

structures

salt exclusion vs. salt excretion

Mangroves are better competitorsin salty environments

SOIL PHYTOTOXINS: IMPACT NUTRIENT UPTAKE

Vmax

KmNH4

+ concentrationN

H4+ u

ptak

e

EFFECTS OFPOREWATERSALINITY

Vmax

KmNH4

+ concentration

NH

4+ upt

ake

low tide

High tide

Spatial Gradients

decreasing soil redox

increasing soil salinity, and sulfide concentrations

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

Gulf menhaden

Brown shrimp

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?