Mangals & Salt MarshesVascular Plant Tidal Communities
Switching gears from algae to angiosperms
Low – energy coastal regions such as estuaries
or coastal habitats protected by barrier islands
blade
holdfast
flower
leaves
stem
roots/rhizomes
• Less tissue specialization
• Happy in salt water
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Zonation Patterns- physical factors and biotic interactions
Types of flowering plants
1.
• More tissue specialization
• Stressed by salt water
Mesophytes/ Glycophytes- grow where freshwater is available & lack
specialized adaptations that prevent water loss
2. Hydrophytes- live in water, partially or fully submerged (seagrass)
3. Xerophytes- have, morphological, anatomical, & reproductive
adaptations to aid in the retention of water ( mangroves & salt
marsh plants)
1.
Halophytes- adaptations to prevent water loss & can grow in
saline habitats
1. Facultative- do not require saline conditions
2. Obligate- specific requirement for sodium to complete their
life cycle
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Zonation Patterns
Salt Marshes
physical
factors
-typically areas of natural salttolerant herbs, grasses, or low shrubs growing on
unconsolidated sediments bordering saline water bodies
whose water levels fluctuates tidally
Over 400 species- 9 maritime formation
biotic
interactions
physical
factors
biotic
interactions
Dave Lohse
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Salt Marsh Zonation
Some adaptations for salt marsh living:
flooding
salinity
Salt
water
Graciliaria
Spartina
Sarcocornia
Distichlis
Juncus
Zostera
+
-
L d
Land
Salt stress
• Epidermal salt glands
• Salt vacuoles – store salt in
stem, drop stems seasonally
• Thick cuticle – reduce contact
• Succulent
S il anoxia:
Soil
i :
• Aerenchyma = tissue with air
spaces
• Lacunae = space in stem to root
Relatively high nutrients - detritus
Soil anoxia
Hypersaline to evaporation
Disturbance from beach wrack
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Some adaptations for salt marsh living:
Ecological Roles of Salt Marshes
Soil Anoxia & Substrate Type:
• Rhizomes- thick anchoring & delicate absorbing roots,
bind unconsolidated sediments to reduce erosion,
release oxygen reduce anaerobic conditions suppress
methane production
1. Primary Production- below ground biomass 90%, 10 x
sequestration rates of terrestrial forest, 90% in soil so
long term blue carbon storage
2. Food Sources- detrital food chain
3 Habitats-important
3.
H b
nursery habitats
h b
for
f marine fish
f h
4. Stabilization of Sediments- root systems
5. Filtration- removal of organic waste by marshes lowers the
sediment and nutrient loading to adjacent shores
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Blue Carbon- carbon sequestration in coastal ecosystems,
mangroves, salt marshes & seagrass beds
Even though global area is 1- 2 orders of magnitude smaller than
terrestrial forests, contribution to carbon sequestration per unit
area of coastal ecosystems is much greater
McLoed et al 2011
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Spartina foliosa – native cord grass
Salt Marshes & Climate Change-
Sacramento- San Joaquin Delta
750,000 acre vast and complex wetland
Levee construction & land drainage changed this to farmland
Drinking water to 25 million people & irrigation of 3 million acres of farmland
This has released 0.9 billion tCO2,
land subsides 1.5 inches a year releasing 22tCO2 per acre
Conservation – Carbon Farming on Twitchell Island
plot
restore native tules & cattails on 15 acre p
plan for 2,500 acres by 2017 costing $5,000 per acre
• Monocot in the g
grass familyy Poaceace
• 3m tall culms (stems)
•Culms & leaves only 1/3 to 1/10 of biomass
•Salt glands excrete excess salt, leave salt crystals on
leaves
• Have lacunae tissue in stems/roots allows oxygen
transport to roots (often aneorobic soil)
• Occur in lowest parts of salt marsh
Greenhouse gas benefits
14 tCO2 per acre per year
soil accretion of more than an inch
per year
Reduce cost of levee maintenance & lower
risk of levee failure
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Spartina foliosa/alterniflora
HYBRID
• Problem in salt marsh communities
in the SF Bay & Puget Sound
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Sarcocornia pacifica – pickle weed
• Dicot- Chenopodiaceae
•Succulent- water containing cells
•Concentrates salt in tissues,
drops stems every year
•Often parasitized by dodder,
Cuscuta salina
• Occurs in the low-mid marsh
Negative impacts:
• Changes physical environment (oxygen, nutrients, hydrology,
accretion rates)
• Displaces native cordgrass (S. foliosa) and pickleweed
• Changes invertebrate community (much less rich)
• Decreases available water – chokes water channels,
decreases foraging area for birds
Grosholz lab, UC Davis
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• Eradication is difficult
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4
Salt marsh ecology: changing interactions
East coast: An experiment
examining the effects of salt
stress on species interactions:
Distichlis sp, the salt grass
• Has salt glands
• Occurs in the high marsh
(Bertness and Shumway 1993, AmNat)
Positive interaction = Facilitation
Negative interaction = Competition
Research question:
Juncus spp, the spiny rush
Is the nature of species interactions
mediated by the physical environment?
• Occurs in the high
marsh
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Salt marsh ecology: changing interactions
The players:
• Spartina zone gets flooded more, less saline
• Juncus zone becomes hypersaline thru evaporation
• Distichlis co-occurs with both Spartina and Juncus
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Salt marsh ecology: changing interactions
The experiment:
• Remove all vegetation in plots of both zones
• Remove neighbors (potential competitors or
facilitators) in half of plots
• Water (alleviates salt stress) in half of plots
• Count percent cover of target species, see whether
target
g species
p
increases or decreases based on
neighbors and physical stress
Distichlis
Juncus
Juncus
Spartina
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Bertness and Shumway 1993, AmNat
Spartina
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Bertness and Shumway 1993, AmNat
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Salt marsh ecology: changing interactions
The experiment:
Salt marsh ecology: changing interactions
The results:
• Remove all vegetation in plots of both zones
• Remove neighbors (potential competitors or
facilitators) in half of plots
• Water (alleviates salt stress) in half of plots
• Count percent cover of target species, see whether
target
g species
p
increases or decreases based on
neighbors and physical stress
Treatments in each zone:
Juncus
Spartina
Bertness and Shumway 1993, AmNat
- Water + Neighbor
- Water - Neighbor “Control”
+ Water + Neighbor “Watered”
+ Water - Neighbor
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A “FACTORIAL” DESIGN
Salt marsh ecology: changing interactions
The results:
Spartina zone (less
stressful):
Spartina outcompetes Distichlis in
both watered and control plots
Distichlis more abundant when
neighbors are removed.
Juncus zone (more
stressful):
modified from Bertness and Shumway 1993, AmNat
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Salt marsh ecology: changing interactions
The results:
Spartina zone (less
stressful):
Spartina zone (less
stressful):
Spartina outcompetes Distichlis in
both watered and control plots
Distichlis more abundant when
neighbors are removed.
Spartina outcompetes Distichlis in
both watered and control plots
Distichlis more abundant when
neighbors are removed.
Competition is prevailing
interaction
Competition is prevailing
interaction
Juncus zone (more
stressful):
Juncus zone (more
stressful):
Control plots – presence of
neighbors increased abundance of
Juncus = facilitation
modified from Bertness and Shumway 1993, AmNat
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modified from Bertness and Shumway 1993, AmNat
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Salt marsh ecology: changing interactions
Salt marsh ecology: changing interactions
The results:
Spartina zone (less
stressful):
The conclusion:
Juncus zone (more
stressful):
Control plots – presence of
neighbors increased abundance of
Juncus = facilitation
modified from Bertness and Shumway 1993
Bertness and Shumway 1993, AmNat
Negative interac
ction
Competition is prevailing
interaction
Alleviating salt stress shifts nature of
interactions from facilitative to competitive
Associational
defenses
Neighborhood habitat
amelioration
Positive interaction
ns
Spartina outcompetes Distichlis in
both watered and control plots
Distichlis more abundant when
neighbors are removed
Physical stress
Watered plots – Neighbors
decrease abundance of Distichlis
25 =
competition
Consumer pressure
modified from Bertness and Callaway 1994,TREE
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Mangal taxonomy
Domain Eukaryote
Kingdom/Clade Plantae
Phylum/Division Magnoliophyta - angiosperms
Class Magnoliopsida
Order Malpighiales
Family Rhizophoracea
Genus
Rhizopora
Mangals
species
mangle- red mangrove
Mangroves & associated tidal marsh communities
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Mangal Distribution
Mangal Genera Share the following features:
1. Species restricted to mangals.
2. Trees exhibit major role in community structure.
3. Morphological specializations, including aerial roots
& vivipary
4. Plants exhibit salt- exclusion physiology
5. Taxonomic isolation from terrestrial relatives
at the level of genera
- Tropical tidal habitats
- 40 species of Mangroves dominate 75% of the tropical
coastline between 25 N & 25 S
- Orders Myrtales & Rhizophrales make up 50% of the species
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Mangrove Forest Classification
1 Coastal Fringe- along protected shoreline berms
2 Overwash- low intertidal
3 Riverine- along streams and rivers and extend several
miles inland
4 Basin- occur in a depression behind a berm or fringing
mangals, connected to streams or tidal creeks
5 Scrub- occur where abiotic conditions are severe due
to limited water
6 Hammock- inland tropical wetlands, isolated by fresh water
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Mangrove Leaves
Adaptations of Mangroves
1. Mechanical adaptations for attachment in soft sediment
2. Aerial roots are common & specialized for diffusion of
gases to subterranean portions.
3. Vivipary- germination of seedlings while fruit remains
attached to tree
4. Seeds & seedlings can survive in salt water & disperse
via salt water
5. Xerophytic modifications- survive with little fresh
water
evergreen
complex leaf anatomy
thick outer walls & cuticles
salt is accumulated in leaves causing succulence and
eventually shed
glandular hairs- function in salt excretion
lenticles- ”cork warts” secrete water & chloride
hypodermis upper layer contains tannins
lower layer contain hydrocytes- water containing cells
6. Halophytic modifications- survive with high amounts of
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salt
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Mangrove trunks & bark
lenticles- dense masses of cells that results in breaks
in the bark
- function in gas exchange
- critical for root survival
40% of root is used for gas exchange
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Zonation patterns
Rhizopora mangle- red mangrove
Red Bark & Leathery Leaves
Vivipary-seedling germinate from fruit while
attached to tree
Upper limit determined by biotic interactions
Lower limit determined by abiotic factors
Stilt roots- develop from the stem “prop”
- develop from a branch “drop”
Lacunae- gas exchange
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Avicennia germinans- black mangrove
Lacunae- gas exchange
Hair on leaves- salt secretion
Cryptovivipary-embryo grows out of the seed
but not the fruit before dropping
Enlargement of airspaces
Air spaces forming channels in
leaves, stems and roots
Also have a structural role
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Aerenchyma tissue- gas exchange
Cable root with Pneumatophores- extend 10-20 cm
above root function in gas exchange
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Avicennia marina- white mangrove
Aerenchyma tissue- gas exchange
Formed by cell separation
Mechanism for root aeration in low
oxygen concentrations
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Mangal Macroalgae
important primary producers
epiphytic algae on roots = to the leaf litter from the tree
Stilt or Cable roots
Nectaries at base of leaves secrete sugar
Hair on leaves- salt secretion
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Water Regulation & Osmoregulation
facultative halophytes- competitive exclusion limits
them to saline habitats
slow growth because they spend a lot of energy dealing
with salt
salt secretors- Avicennia- 33% of the salt
non secretorssecretors Rhizophora - exclude 90% of salt
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Coastal Resilience & Mangroves
Ecological roles of Mangals
1. Coastal Resilience
2. Filtering land runoff
3. Stabilization of sediments
4. Trapping sediments
5. Primary Production
6. Nursery Habitats
Storm surge- low pressure & high winds raise water level at the coast
-peak water levels can exceed 7m in heightflooding
Mangroves can reduce storm surge and surface waves
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Blue Carbon- carbon sequestration in coastal ecosystems,
Loss of Mangals
mangroves, salt marshes & seagrass beds
extraction, pollution & reclimation
Has lead to declines of finfish & commercial shrimp
these species depend on detrital & benthic microalgae
Long term pollution from oil spills cause mutations in the trees
Habitat Loss
seagrass 1.5% yr
mangroves 1.8% yr
tropical forests 0.5% yr
Even though global area is 1- 2 orders of magnitude smaller than
terrestrial forests, contribution to carbon sequestration per unit
area of coastal ecosystems is much greater
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McLoed et al 2011
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