Marine Botany Exam 3

nursery, habitat, food source, nutrient cycling, sediment retention, reduce erosion, storm surge protection

ecological functions of salt marshes

salt marshes

found where freezing air temps occur with regularity

mangals

limited to latitudes remain at 20C or higher

salt marsh

a halophytic grassland on alluvial sediments bordering saline water bodies where water level fluctuates either tidally or nontidally

salt marshes

found in areas where the accumulation of sediments is equal to or greater than the rate of land subsidence and where there is adequates protection from destructive waves and storms

river mouths, bays, protected coastal plains, protected lagoons

Salt marshes are found in/near:

salt marsh

geomorphology:

- predominantly intertidal areas

- gently sloping shorelines

- protection from wave and storm energy

- strong sediment supply from upland run-off

wetlands

classified as forming in either marine-dominated or deltaic areas

deltaic marshes

found in south Atlantic and in Gulf of Mexico

shoreline features that allow for the development of salt marshes

- shelters of spits, offshore bar, and islands

- protected bays

- estuarine zones

shelters of spits, offshore bars, and islands

traps sediment on lee side; protects marsh from open ocean

protected bays

large bays with shallow areas and large sediment supply allow for extensive marsh development

estuarine zones

shores of estuaries where shallow water and low gradients allow for sediment deposition; tidal action has to maintain higher salinities

saline conditions, waterlogged sediments

salt marsh vegetation has 2 key features:

- adaptation to _______ _______

- ability to grow in/be exposed to ______ _______ (including peat deposits)

mesophytes, hydrophytes, xerophytes

Flowering plants grouped into 3 classes based on adaptations to obtain and retain water:

mesophytes

plants that grown in habitats where freshwater is available in the sediment; lack specialized adaptations to prevent water loss (e.g. wheat, beet)

hydrophytes

plants that live in water, partially or wholly submerged (e.g. seagrasses)

xerophytes

plants that have morphological, anatomical, and reproductive adaptations to aide in retention and uptake of water (e.g. salt marsh plants, mangroves)

halophytes

plants that have adaptations to prevent water loss and to grow in saline habitats

facultative halophytes

halophytes that do NOT require saline conditions for growth

obligate halophytes

have a specific requirement for sodium and not potassium; require salt to complete life cycle

falcultative

Most salt marsh species are _______ halophytes

hemicryptophytes

form of clonal growth where perennating buds are situated at or just below the soil surface

- most common morphology for salt marsh plants

therophytes

annual plants; plant that overwinters as a seed

- varies across latitude and salt marsh groups

- dominant in mediterranean and semi-arid climates

continental drift, dispersal by birds/vegetative reproduction

Salt marsh distribution patterns attributed to:

sporobolus alterniflorus

- smooth cordgrass

- monocot in family poaceae

2 main forms

- tall; found along tidal creeks

- short; found in upper marsh

sporobolus alterniflorus

development of different forms attributed to phenotypic expression based on edaphic (soil) factors

sporobolus alterniflorus

- clonal species

- sympodial branching

- new shoots and roots produced from rhizome

sympodial branching

primary axis that develops from a series of short lateral branches and often has a zigzag or irregular forms

unbranched or ephemeral

2 types of roots for sporobolus alterniflorus

sporobolus alterniflorus

shoots and leaves account for 1/3 to 1/10 of plant biomass - the rest is belowground

sporobolus alterniflorus

stems

- hollow center

- ring of lacunae alternating with vascular bundles on outside of stem

- both continuous to roots

sporobolus alterniflorus

leaves

- produced by basal intercalary meristem

- smooth flat blades with longitudinal furrows

- contain epidermal salt glands

Juncus roemerianus

- black rush

- monocot

- 8 genera

- most genera found in southern hemisphere

- has both fresh and salt water species

Juncus roemerianus

- clonal plant

- subterranean branching rhizome

- fibrous root system

Juncus roemerianus

-rhizomes covered with suberized (corky tissue) scale leaves

- lacunae in cortex

- endodermal layer limiting cortex from pericycle

Juncus roemerianus

- erect stem with lacunae

- produce long needle like leaves up to 2m tall

Juncus roemerianus

- eaves oval in cross section

- blades develop from basal intercalary meristem

- central portion of blade with parenchymatous mesophyll, vascular bundles, and lacunae

Juncus roemerianus

- epidermis is lignified with thick cuticle

- flowers occur in dense cymes

cymes

an inflorescence in which each floral axis terminates in a single flower

Salicornia virginica

- pickles weed, American Glasswort

- dicot member

- stem and leaves are succulent

- appear swollen due to abundance of water - containing cells

succulent

plant with fleshy tissues able to conserve moisture

Salicornia virginica

- perennial species

- has a thick and waxy cuticle

- stem, procumbent - produces short erect branches

- stem produces advantageous roots to extend area

Salicornia virginica

- blades reduced to scales

- succulent petioles wrapped around stem giving segmented appearance

- petioles

petioles

a slender stem that supports the blade of a foliage leaf

variable salinity, flooding, low oxygen

plants have to be adapted to live in harsh environments:

edaphic changes, lower photosynthesis, damage or uprooting of plants due to water movement, anaerobic sediments

high tides result in:

Thickness of oxidized layer directly related to:

- rate of O2 transport across the atmosphere-surface water interface

- population of oxygen-consuming organisms present

- photosynthetic oxygen production by algae within the water column

- surface mixing by convection currents and wind action

importance of Rhizomes

- storage organs during periods of dormancy

- vegetative expansion

- reduce erosion due to anchoring and absorbing roots

rhizosphere

narrow region of soil that is directly influenced by root secretions and associated soil microorganisms

increased lignification, complex epidermal development, well-developed bundle sheaths

xerophytic adaptations to maximize water retention in stems, leaves, and roots

succulent, thick, dry-type

3 types of xeric leaves found in salt marsh plants

succulent

store water and dilute internal salt concentrations

thick

increase vascular, water-storage and photosynthetic tissue

dry-type

have enhanced cuticular resistance to water loss, produce epidermal hairs, and can curl to reduce water loss

dry-type

S. alterniflorus has _____ - _____ leaves

water storage, dilution of inorganic salts, reduction in surface area (reduces water loss)

succulence is an adaptation for:

edaphic factors

- high sodium and chloride concentration

- limited essential nutrients

- anaerobic conditions

tidal immersion

- temperature shock

- changes in photoperiod

- mechanical effects of tidal currents

- siltation of leave by sediment (blocks stomates)

middle to upper

Where is salinity the highest concentration in salt marshes?

osmotic potential

to take up groundwater there has to be a gradient in ______ _______ within the plant

below

roots of a halophyte has to be ______ that osmotic potential to take up water

osmoconformers, osmoregulators

Most halophytes considered to be either:

osmoconformers

shows a gradient in osmotic potential between soil and plant

osmoregulators

lacking a gradient and exhibiting sharp changes in internal ion concentration when subjected to changes in external salinity concern

shoot

regulation of _____ salt content accomplished by:

- ion exclusion in roots

- growth and succulence

- shedding

- recretion

- root discharge

- controlling water loss

root discharge

move salt from growth areas to roots; then discharged into rhizosphere

controlling water loss

reducing transpiration; lowers water needed and reduces subsequent salt uptake

enzymes

________ of halophytes adapted to tolerate higher salinity without adjustments

production of organic solutes

effective method at reducing salt stress

dehydration

results in loss of turgor pressure:

- photosynthetic and metabolic shutdown

- curling

- wilting

ferns, bryophytes, algae, seagrasses, epiphytes

variety of types of plants found in salt marshes:

tides, elevation, climate, zonation, competition

driving abiotic/biotic factors of salt marshes

zonation

- due to differing vertical ranges of species

- not just marsh vegetation - microalgal, seaweed, and faunal components also zoned

latitude, physical factors

criteria used to develop zones

storms, fires, ice rafting, wrack deposition

distubrance common in salt marsh communities

farming, strip mining, land reclamation, insect control

human uses of salt marshes

grazing, harvesting, turf cutting, farmland after diking and draining

common uses of salt marshes for agriculture

increased salinity, sediment starvation downstream, nutrient limitations

channelization for flood protection and insect treatment causes:

lack of sediment

can leaded to large scale loss of salt marsh

rising salinity

reduces seed banks and plant recruitment

marsh loss

decreases filtration and water clarity

industrial activity

adds heat and other stressors

construction, dredging, filling

largest present-day impact due to urban expansion

60%

presetn global loss of salt marsh estimated at __

enforcement, liability issues, jurisdiction of regulators

PTD not perfect solution problems with:

clean water act

protected wetland areas

restrict inflow of pollutants, strop dredge and filling, restore coastal wetlands

developed detailed management plans:

USACE

plans must be approved by

sackett v. EPA,

- wetlands must have a "continuous surface connection" to navigable waters to be federally protected

- excludes many isolated or intermittently connected salt marshes

seagrasses

marine flowering plants that live fully submerged in salt water

1. adapted to saline 2. grow when fully submerged 3. secure anchoring 4. hydrophilous pollination 5. compete successfully

what defines a seagrass?

hydrophilous

water emdiated, abiotic pollination

high salinity, wave energy, low light

marine life presents challenges for seagrass:

seagrass

- complex root structure

- photosynthesis restricted to cells in leaves

- transport minerals in aerenchyma and lacunae

- sexual reproduction via flowers, fruits and seeds

marine algae

- simple holdfast

- photosynthesis undertaken by all cells

- uptake of minerals from water column via diffusion

- sexual reproduction via spores

~100 million years ago

seagrass returned to marine life:

succession

shifts from small fast colonizing pioneer species to larger slow growing species

climax community

can be monospecific or multi-species

maximum biomass

shifts from above-ground to below-ground as community matures