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QUIZ #8. Draw the IDH curve. When and why is species diversity highest according to IDH? Explain how anthropogenic disturbance can be either beneficial or detrimental. How can wetlands function as a transitional community (zone) between open lakes and upland terrestrial forest habitats?
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QUIZ #8 Draw the IDH curve. When and why is species diversity highest according to IDH? Explain how anthropogenic disturbance can be either beneficial or detrimental. How can wetlands function as a transitional community (zone) between open lakes and upland terrestrial forest habitats? What is the difference between (or define, up to you) allogenic and autogenic succession. Give an example of both primary and secondary succession.
RANGE OF PRODUCTIVITY: CLIMATE AND LOCAL ENVIRONMENTAL VARIABLES
Forces leading to adaptation Anoxia: lack of oxygen Salinity: fluctuating or high salinity Soil toxins: sulfide, methane, etc. Nutrient stress: low nitrogen or phosphorus availability Submergence: anchorage, locomotion, change in C source, wave energy, light 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
Loblolly pine root Flooded vs. Non-flooded and ethylene production Loblolly pine seedling stem
waxy leaves and viviparous seedlings lenticels specialized root structures Mangrove Adaptations salt exclusion vs. salt excretion
Mangroves are better competitors in salty environments
Vmax NH4+ uptake Km NH4+ concentration SOIL PHYTOTOXINS: IMPACT NUTRIENT UPTAKE
Vmax NH4+ uptake Km NH4+ concentration EFFECTS OF POREWATER SALINITY
High tide low tide Spatial Gradients increasing soil salinity, and sulfide concentrations decreasing soil redox
PHOTOSYNTHETIC PATHWAYS C3 PATHWAY C4 PATHWAY
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.)
Estuarine-dependent life cycles Brown shrimp Gulf menhaden
Quiz # 8 Why is nitrogen fixation inhibited by aerobic conditions? Describe one way in which bacteria deal with anoxia. Describe a mechanism that allows hydrophytes to deal with salinity stress. What is the source of inorganic carbon for plants photosynthesizing under water (i.e., SAV)? What microbial process gives rise to reduced inorganic nitrogen?