Transcript Aquatic Ecology and Diversity of Belize I

Streams (Rivers)
• Stream = water flowing downhill in a
defined channel.
• Amount of flow significant. Usually varies
seasonally. (wet season & dry season)
• Substrate important. (bedrock, gravel, silt)
• Amount of floating particles (turbidity) is
important.
What physical conditions do flow,
substrate, & turbidity affect?
Energy in Streams
• Photosynthesis can occur in stream via
periphyon (attached “algae”) or
macrophytes (larger multicellular
photosynthesizers).
What conditions need to occur for
photosynthesis to happen in stream?
• Most streams heavily dependent on
external organic matter inputs (leaf litter)
to support their food webs.
N. Amer. vs. S. Amer. Streams
• How do temperature and sunlight vary
between temperate N. America and
tropical S. America?
• How does precipitation vary between
temperate N. America and tropical S.
America?
• How do leaf litter inputs vary between
temperate N. America and tropical S.
America?
N. Amer. Stream
Food Web
runoff or
groundwater entry
leaf
litter
conditioning
periphyton
(microbial colonization)
bacteria
& fungi
coarse
organic matter
grazing grazing
fishes
insects &
crustaceans
shredding
dissolved organic
compounds
fine organic
matter
insects &
crustaceans
collecting
“predatory”
fishes
predatory
insects &
crustaceans
insects, crust.,
nematodes, &
annelids
bacteria
& fungi
S. Amer. Stream
Food Web
runoff or
groundwater entry
leaf
litter
conditioning
periphyton
(microbial colonization)
bacteria
& fungi
coarse
organic matter
grazing
FISHES &
crustaceans
herbivore
dissolved organic
compounds
fine organic
matter
FISHES &
crustaceans
detritivore
“predatory”
FISHES
bacteria
& fungi
FISHES, crust.,
nematodes, &
annelids
Relatively few aquatic insects.
Aquatic Insect
O-rama
@ lower trophic levels
?
Fish O-rama
@ lower trophic
levels
Estuaries
• Estuary = semi-enclosed body of water
where freshwater from land drainage
dilutes sea water.
• Amount of stream flow again significant.
Usually varies seasonally. (wet season &
dry season)
• Tidal and wave activity also significant.
• Salinity varies.
• Much organic matter deposited (mud).
Sea Grass Beds
• Seagrasses live completely submerged
and can tolerate fully marine water.
• Require a soft particulate substrate and
low turbidity.
Coral Reefs
• Reef = a solid outcrop in shallow water
reached by sunlight.
• Coral Reef = a solid outcrop created by
the action of coral animals in shallow
water reached by sunlight.
• Coral reefs require shallow, 23-25 º C,
clear water (low in nitrogen).
• Very sensitive to perturbation and stress.
Coral Animals
Fringing Coral Reefs
flat
back reef
reef
face
Acropora palifera Forms
Coral Bleaching
Coral Reef Food Webs
• Primary producers = algae in corals,
periphyton (algae), and macrophytic algae.
• External inputs = plankton from open
water (usually very important)
• Trophic patterns very complicated.
• Cleaner fishes.
• Coral eaters
(parrot fishes).