mudflats

Question 1

Location

Answer 1

• all over the world
• intertidal
• near freshwater and sediment output(river, stream)

Question 2

Physical characteristics (substrate elements):

Answer 2

Substrate: MUD = water + sediment + detritus
Sediment has a diameter of 0.07 mm or less (silt,
clay and detritus)
Sand: 0.02 – 2 mm
Silt: 0.002 – 0.02 mm
Clay: < 0.002 mm
Detritus = non-living particulate organic matter

Question 3

slope

Answer 3

flat

Question 4

energy

Answer 4

low

Question 5

the formation of mudflats

Answer 5

Erosion of rocks
Sediment transport by rivers or ocean
Deposition of sediment – occurs mostly at high, slack tide
Accumulation of sediment to make mudflat
Flat, wide & shallow 🡪 encourages further deposition

Question 6

temperature

Answer 6

stable within sediment

on top of the mudflats it can vary with air temperature and tides

Question 7

light

Answer 7

none within sediment

Question 8

chemical characteristics:
salinity
nutrients

Answer 8

Salinity: within sediment is very stable
On top of mudflats at low tide and in burrows, salinity can vary with run-off, precipitation and evaporation
Nutrients: high organic content of sediment (detritus)
Streams / rivers deliver nutrients in fresh water
And photosynthetic bacteria, diatoms, sea lettuce, eel grass fix carbon and add it to ecosystem

Question 9

oxygen

Answer 9

low in sediment because:

Little space between sediment particles 🡪 no diffusion

No light 🡪 no photosynthesis within sediment

A very thin layer of oxygenated sediment above a
black, anoxic (= no oxygen), sulfide-rich layer

Question 10

hydrogen sulfide (H2S) why, colour

Answer 10

high within sediment
Anaerobic bacteria decompose organic material and produce toxic H2S
Black colour is due to reaction of H2S with iron
oxides in silt
Toxic / poisonous!!

Question 11

biological characteristics:
biodiversity
biomass
productivity

Answer 11

biodiversity- low
biomass- high
prod: moderate

Question 12

meiofauna

‘meio’ = between; ‘fauna’ = animals

Answer 12

Interstitial organisms (spaces between particles)

Size: 62 um to 0.5 mm

Benthic invertebrates (animals from many phyla)

Question 13

biological adaptations to mudflats for organism living on the surface

Answer 13

Living on the surface (to avoid low O2, high H2S)
avoid predators: Crabs use camouflage, temporary burrows,
autotomy, and running away fast hard shell, camouflage
Ulva & diatoms must live on surface for light

Question 14

bio adaptations burrowing

Answer 14

Most of the organisms are found within the sediment
Burrowing is an adaptation for feeding, evading
predators and avoiding fluctuations in
environmental conditions
During low tide burrow water becomes stagnant

Question 15

burrowing species adaptations

Answer 15

eversible proboscis and feeds as it burrows

clams use their foot to borrow

Question 16

how are the burrowers in mudflats compared to sandy beaches

Answer 16

slower

Question 17

living in the dark

Answer 17

eyes are reduced (shrimp) or absent (clams)

relly on smell rather than on vision

Question 18

low oxygen/high sulfide adaption

Answer 18

• Burrows open to surface to get oxygen-rich,
  sulphide-poor water e.g. clams, worms, shrimps
  -Euryoxic = tolerance to a wide range of oxygen
  levels
• Clams: long siphons allow for deep burrowing – can still reach surface for oxygen & plankton

Question 19

Euryoxic

Answer 19

= tolerance to a wide range of oxygen

levels

Question 20

clams adaptation to low oxygen/high sulfide

Answer 20

Clams can close up at low tide to keep sulfide out

Clams have low metabolic rates 🡪 low oxygen
requirements

Question 21

adaption at low oxygen/low sulfide for ghost shrimp

Answer 21

Deposit feeders that burrow continuously
Therefore must be tolerant to low O2, high H2S
Have low metabolic rates 🡪 low oxygen
requirements

Question 22

mud shrimp adaptation to low oxygen/low sulfide

Answer 22

Filter feeders
Make permanent burrows (U- or Y-shaped) which
they line with mucus
Mucus has iron in it which binds H2S 🡪 excludes sulfide from burrow water

Question 23

worms adaptation to low oxygen/low sulfide

Answer 23

low metabolic rates 🡪 low oxygen requirements
detoxify sulfide by converting it to a non-toxic form or by binding it to iron (hematin)
Lugworm (Abarenicola pacific): Hemoglobin with high O2 affinity (binds O2 at low
levels)

Question 24

human impact on mudflats

Answer 24

sewage, disturbance, chemical/oil spills, agricultural run-off of fertilizer and pesticides

Question 25

what is called the tolerance to a wide range of oxygen levels?

Answer 25

euryoxic

Question 26

what do clams to avoid high H2S low O2

Answer 26

Use their siphons for deep burrowing

Question 27

what does ghost shrimp have to survive high amount of sulfide

Answer 27

Hepatopancreas = liver-like organ which detoxifies sulfide to sulfate or thiosulfate

Question 28

how’s h2s produced

Answer 28

by anaerobic bacteria that decompose organic material

Question 29

bio adaptation to living on the surface, running

Answer 29

autotomy