3/4Wetland Adaptations and Biogeochemical Cycling in Ecosystems

What are the main stresses that organisms face in wetlands?

Flooded conditions

What additional stress do coastal areas present for organisms?

Salt tolerance.

What are 'Tolerators' in the context of wetland adaptations?

Organisms that have functional modifications to survive and function efficiently in the presence of stress.

What are 'Regulators' in wetland environments?

Organisms that actively avoid stress or modify it to minimize its effects.

What is a cost associated with adaptations in organisms?

Expenditure of energy to protect cells from external stresses.

How can adaptations be classified in wetland organisms?

Adaptations can be classified as those that Tolerate and those that Regulate external stresses.

What types of adaptations do bacteria/protists exhibit?

Biochemical adaptations at the organelle level.

What types of adaptations do plants exhibit?

Physiological/structural adaptations at the cell/tissue level.

What types of adaptations do animals exhibit?

Behavioral adaptations at the organ/individual level.

What is an 'obligate' organism?

An organism that can only exist in a particular environment or by assuming a particular role.

What is a 'facultative' organism?

An organism capable of functioning under varying environmental conditions.

What is a key characteristic of unicellular organisms adapted to anoxia?

They often rely on electron acceptors other than O2.

What is Desulfovibrio known for?

It can only use Sulfate (SO4) as its electron acceptor

What is aerenchyma?

Air spaces within plant tissues that allow O2 to diffuse from aerial portions to the roots.

What are adventitious roots?

Roots that form in response to hypoxic conditions

What is stem hypertrophy?

Buttressing that occurs in certain wetland trees

What is the purpose of fluted trunks in wetland trees?

To provide stability and support in waterlogged conditions.

What adaptation occurs in plants during rising water levels?

Rapid stem elongation to ensure photosynthetic organs remain above water.

What are lenticels?

Tiny pores on roots that allow gas exchange

What happens to intracellular O2 concentrations in roots if lenticels are blocked?

Concentrations can fall to less than 2% within two days.

What is the role of ethylene in wetland plants?

It stimulates the formation of organs that assist in translocating O2 to the roots.

What is the significance of shallow roots in wetland plants?

They help vascular plant roots avoid anaerobic conditions.

What is the adaptation of the red mangrove in tropical areas?

It grows on arched prop roots that are covered with lenticels.

What is the effect of waterlogged conditions on the evolution of certain plants?

It leads to the development of specialized structures like pneumatophores.

What are pneumatophores?

Structures that originate from the roots of certain wetland plants and extend upwards

Which two species are known to have pneumatophores?

Cypress and black mangrove.

What role do lenticels play in pneumatophores?

They help improve gas exchange with the root system.

What happens to the oxygen supply when the roots of flood-sensitive upland plants are inundated?

The oxygen supply rapidly decreases

What are the consequences of anaerobic conditions for upland plants?

Cell division stops

How do wetland plants adapt to anoxic conditions?

They have adaptations like pressurized gas flow and rhizosphere oxygenation.

What is pressurized gas flow in wetland plants?

Air moves into internal spaces of aerial leaves and is forced down through aerenchyma by pressure gradients.

What is rhizosphere oxygenation?

The process where wetland plant roots leak oxygen into surrounding soils

What happens to nutrient absorption in plants during anoxia?

Nutrient absorption is typically affected first

What are two ways wetland plants can overcome ammonium absorption issues?

Oxidizing NH4 to NO3 in the oxidized rhizosphere or directly absorbing NH4.

What is sulfide avoidance in wetland plants?

Mechanisms to oxidize sulfide to sulfate in the rhizosphere and accumulate sulfate in vacuoles.

What are some whole plant strategies to avoid flooding?

Timing seed production during non-flood conditions

What adaptations do animals have to cope with anoxia in wetlands?

Adaptations include biochemical responses

What are specialized organs in animals for gas exchange?

Development or modification of regions such as gills or parapodia.

How do animals improve oxygen conditions in low-oxygen environments?

By moving to oxygen-rich areas or using ciliary action to move water across gills.

What are respiratory pigments?

Modified pigments that improve oxygen carrying capacity in animals.

How do vertebrates compare to invertebrates in adapting to anoxic conditions?

Vertebrates generally have less ability to adapt to anoxic conditions than invertebrates.

What is the primary anaerobic respiration pathway used by vertebrates?

Glycolysis

What is the significance of metabolic responses in animals under anoxic conditions?

They help maintain the internal environment despite external stressors.

What is a key adaptation of gills in intertidal habitat organisms?

Gills are highly sclerotized to prevent sticking together when out of water.

Which organisms have specialized blood pigments with a high affinity for O2?

Some nematodes

What is a characteristic behavior of fiddler crabs?

They are active at low tides and retreat into burrows when tides rise.

How do fiddler crabs cope with low oxygen levels in their burrows?

They can remain inactive for several tidal cycles when oxygen levels drop.

What is the feeding adaptation of infaunal polychaetes?

They can absorb amino acids directly from their environment.

What do mud-dwelling organisms use for selective feeding?

Adaptations such as pseudopods

What happens to bottomland hardwood areas during winter?

They are flooded and then drain in the spring.

Why do many fish species move into bottomland hardwood areas in spring?

To take advantage of elevated productivity.

What is a consequence of high external salt concentrations for organisms?

They must adapt to lower the osmotic concentration of their body.

What are halophiles?

Unicellular organisms that maintain internal osmotic concentrations higher than their surroundings.

What are the two main strategies plants use to cope with salt stress?

1. Barriers to prevent salt entry. 2. Specialized organs to secrete salts.

How do mangroves exclude salt?

Primarily at the root periderm and exodermis

What is the role of salt glands in Spartina spp.?

They secrete excess salts along the leaves.

What are the two types of osmotic strategies in animals?

Osmoconformers and osmoregulators.

What is the difference between euryhaline and stenohaline organisms?

Euryhaline organisms tolerate varying salinities

What adaptations do hyperosmotic organisms like brown shrimp have at low external salt concentrations?

They concentrate Na+ and Cl- ions.

What are some adaptations animals have to low oxygen conditions?

Better circulation

What is the energy cost associated with adaptations to wetland stresses?

Adaptations can lead to less efficient cellular operation or energy expenditure to protect cells.

How do vascular plants counter anoxia?

By having pore spaces in cortical tissues to transport O2.

What is the significance of behavioral modifications in motile organisms regarding salt?

They help avoid high salt concentrations by moving.

How do sessile plants increase offspring survival in saline environments?

Through timing of seed release

What is biogeochemical cycling?

The transport and transformation of chemicals in ecosystems.

How does hydrology influence wetland biogeochemistry?

Hydrology strongly influences the chemical reactions and spatial transport of materials in wetlands.

What are the two main components of wetland biogeochemistry?

Intrasystem cycling (chemical transformations) and exchange/export of chemicals between the wetland and its surroundings.

What conditions are dominant in wetlands?

Anaerobic conditions

What defines an 'open' wetland?

A wetland with abundant exchange of materials with adjacent areas.

What is an example of an open wetland?

Bottomland forests or tidal wetlands.

What defines a 'closed' wetland?

A wetland with little exchange of materials with adjacent areas.

What is an example of a closed wetland?

Ombrotrophic bogs or cypress domes.

What are hydric soils?

Soils that formed under conditions of saturation

What distinguishes organic soils from mineral soils?

Organic soils contain more than 20% organic matter

What is peat?

Undecomposed organic soil that often has over 80% organic matter.

What is bulk density (BD)?

A measure calculated by dividing the dry weight of soil material by the unit volume.

What is the impact of decomposition on bulk density?

As decomposition occurs

What are redoximorphic features?

Characteristics developed in mineral soils when flooded for extended periods

What is gleying?

The result of chemical reduction of iron and manganese

What is redox potential?

A measure of the electron availability in a solution

What happens to oxygen in inundated soils?

Oxygen is consumed quickly due to slow diffusion in water

What is the order of preference for electron acceptors in wetland soils?

Oxygen (O2) > Manganese (Mn) > Iron (Fe) > Sulfur (S) > Carbon (C).

What occurs under highly reduced conditions in wetlands?

Carbon is reduced to methane gas (CH4).

What role does nitrogen play in coastal wetlands?

Nitrogen is a limiting nutrient

What is the significance of nutrient cycling in wetlands?

It affects the overall productivity and health of wetland ecosystems.

What factors influence nutrient cycling rates in wetlands?

Rates of production and decomposition

What are the characteristics of organic soils classified as histosols?

They are composed of plant remains in various stages of decomposition

What happens to iron and manganese under saturated conditions?

They are reduced to soluble forms (Fe2+ and Mn2+) that can be leached from the soil.

What is the impact of anaerobic conditions on nutrient availability?

It prevents aerobic root respiration and affects the availability of nutrients for plants.

What is the relationship between redox conditions and nutrient cycling?

Redox conditions can significantly affect the rate of nutrient cycling in wetland systems.

What is swamp gas?

Swamp gas is a term for methane

What is the first step in the nitrogen cycle?

The conversion of N2 gas to organic nitrogen

What forms of nitrogen can living organisms use?

Ammonium (NH4)

Which forms of nitrogen cannot be assimilated by most living organisms?

Dinitrogen (N2) and ammonia (NH3).

What enzyme is responsible for nitrogen fixation?

Nitrogenase

What is nitrogen mineralization?

The process where organisms convert organically bound nitrogen to ammonium (NH4).

What happens to ammonium (NH4) in wetland soils?

It can be taken up by plants and microorganisms

What are the essential micro-nutrients mentioned?

Iron (Fe) and Manganese (Mn).

In what form are iron and manganese more soluble and available?

In their reduced forms

What can happen to ferrous iron in wetland soils?

It can reach toxic concentrations and prevent plant nutrient uptake when oxidized around plant roots.