Chapter 10: Mangrove Forests and Seagrass Beds Flashcards
What is a mangrove?
- woody trees or shrubs that grow at the sea/land interface in tropical estuaries and inlets.
- true mangroves
- mangrove associates
what is the difference btwn true mangroves and mangrove associates?
True: only occur in the interface
Associate: found elsewhere, such as rainforests
what are the three main types of mangroves?
- riverine mangroves
- tide-dominated mangroves
- basin mangroves
Riverine mangroves
- low tidal range and dominance of FW flow
- deltas of major rivers
- most of mangrove forests in Asia
Tide-Dominated mangrove
- fully intertidal and full-strength seawater
- high-wave action
- ‘fringing’ mangroves
- pioneer spp
Basin mangroves
- the landward side of fringing mangroves
- low tidal currents and wave action
Where are mangroves found?
- coincides very closely with coral reefs
- 20*C isotherm on either side of the equator
- modified by either warm currents extending distribution or cold currents in the tropics
- muddy shores
Where is the highest and lowest diversity of mangroves?
- Highest: indo-west pac
- Lowest: carribbean/w-atl.
Describe the pattern of distribution of species for mangrove forests
a) the fringing mangrove of species at sea edge (pioneer)
b) other true mangrove families (behind fringe spp), mid-swamp
c) behind the true mangroves are the associated mangroves and forest plants
what two main factors limit plant distribution?
- increased salt level
- waterlogged sediment
How do mangroves survive living in a marine environment with waterlogged mud? (3)
- rhizophora
- bru-guiera
- avicennia
Rhizophora
root system which extends the tree up to 2m off the ground
Bru-guiera
root system that breaks the soil surface and produces ‘knees’ above the sediment surface
Avicennia
root system symbolic of mangroves
- vertical tubes (pneumatophores)
- abundant lenticles for air uptake (on each tube)
What two problems does a haline environment present to mangroves?
how is this fixed?
a) disrupts cellular mechanisms
- > secretion of excess salt through the bark or leaves
b) reduces the osmotic difference btwn the root and the sediment
- > only takes water from the top 50cm of soil (FW less dense than seawater)
- >exclude 90 salt at root
how do mangroves reproduce?
- flowers pollinated by wind or bees
- vivipary (embryo) grows on plant
- falls from parent and carried by current until it settles and takes root.
what are some terrestrial organisms associated with mangroves
- insects (ants termites and mosquitos)
- beetles
- vertebrates (crab-eating frog)
- birds
what are some marine organism associated with mangroves?
- barnacle, seasquirt
- algal communities, snails
- tree bark provides ecological niche
- mudskipper, crabs in muds
- leaf litter provide food for grapsid crabs.
what roles do mangrove play in ecosystems?
- shoreline stabilization
- nutrient input
- energy flux between mangrove and marine system
- provision of a nursery for fish species that recruit to local fisheries and coral reefs
where are seagrass found?
shallow and sheltered coastal waters
-anchored in sand or soft areas
how do seagrasses reproduce?
They are angiosperms:
- hydrophilous pollination
- clonal propogation
- ramet
- rhizomes
- seasonal leaf growth
which species rely on these as grazers?
- dugongs
- manatees
- turtles
are some factors structuring the assemblages associated with seagrass?
- highly productive systems
- obligate inhabitants
- nursery, shelter, and food supply
- pipefish and sea horse (strong association with SG beds and can lead to their protection)
what are the ecological roles that seagrass beds play?
- CO2 storing and O2 production
- Nursery for several species
- Stabelizing sediment
- settling of particles and clearing the water
