BL1006 - Mangroves

Mangroves ideal temperature:

>20C

2 main groups of mangal vegetation:

Old World Mangal -60 plant species
New World Mangal -10 plant species

What kind of sediment is it found?

Soft sediment
Muddy/Sandy

Mangrove Forests

Florida/ West Indies
South, Central Americas
West Africa
SE Asia
North Australia
South Japan
West and East Asia

Salinity fluctuations

tidal, flooding and monsoons

Distribution of plant species explained by?

Salinity gradients

supralittoral zone

Washed by seawater only at high tide or by splashing

salinity gradient of:

increased immersion and salt innudation

salt marsh species settle:

on the salty sand patches within the forest or its backward zones

Mangrove tree problems:

- Salt
unstable substratum
- anaerobic substratum
- propagule

Prapagule

seedling dispersal

Halophytes

SALT GLANDS ON THE LEAF SURFACE OR HAVE THICK WAXY LEAF TO PREVENT WATER LOSS (E.G. SEA HOLLIES, ACANTHUS SPP.)

some accumulate salt in

old or shedding leaves

Pneumatophores

breathing roots to obtain oxygen from air

Pneumatophore example

AVICENNIA SPP.

root system modifications for

support

examples of root modifications

- peg
- prop/stilt
- knee roots

propagule dispersal

plants have viviprary:

seed germinates while still attached to the parent plant

propagule dispersal example

RHIZOPHORA SPP.

Seedlings of vivparous mangrove species

Rhizophora mucronata
Aviennia marina

Range of sediment sizes

sand to mud

algal assemblages

richest in shallow areas with a mixture of hard and soft substrata

sediments have a variety of

epibenthic, infaunal and meiofaunal invertebrates

sediment problems

- oxygen
- methane
- deeper waters can become toxic
- sulphate-reducing bacteria
- tidal inundation
- high turbidity

Fiddler Crab

air roots and aeration for oxygen levels

high methane in sediment

anoxia

effects of anoxic deep waters

fish distributions

bacteria are critical to nutrient cycle of

nitrogen

Sulphate reducing bacteria

desulfovibrio

tidal inundation

less frequent towards land and sediment may be dark and anaerobic

high turbidity of water column due to

amount of sediment in suspension may affect light penetration

what percentage of macrophyte primary production is not directly grazed?

90%

how does it enter local food chain

partly as particulate detritus and partly as dissolved organic matter

DOM

dissolved organic matter

manglicolous fungi function

decompose mangrove leaf litter

organic detritus and nutrients from mangrove litter

can enrich coastal sea and thus support fisheries