Estuarine food webs

Question 1

what are the different types of tidal regimes in an estuary

Answer 1

Microtidal - <2m range
Mesotidal - 2-4m range
Macrotidal - 4-6m range
Hypertidal - >6m range

Question 2

What are the zones on an estuary

Answer 2

Eurohaline - >30psu
Polyhaline - 18-30 psu
Mesohaline - 5-18 psu
Oligohaline - 0.5-5 psu
LImnetic - <0.5 psu

Question 3

what is the climate like at the top of the estuary

Answer 3

clay soil
lots of mixing of water
turbid water
warmer
less oxygen

Question 4

what is the light climate like in an estuary

Answer 4

turbid water reduces the Euphotic zone so phytoplankton are light-limited at high tide
phytoplankton exposed to sunlight at low tide when there is no water

Question 5

what is the nutrient climate like in an estuary?

Answer 5

Hypereutrophic

the food web is very busy so there are lots of anaerobic areas, leads to phosphorus leakage

Question 6

what is the majority of phytoplankton like in an estuary

Answer 6

most are attached to rocks and protected from dehydration at low tide by a biofilm

Question 7

How are filter feeders and deposit feeders distributed throughout the estuary

Answer 7

more filter feeders at the mouth

more deposit feeders at the river

Question 8

Estuarine invertebrates

Mytilus

Answer 8

Mussels

filter feeders with inlet and outlet siphons

Question 9

Estuarine invertebrates

Hydrobia

Answer 9

mud snails
300,000 per m2 - so lots of intraspecific competition
feed on biofilm using net

Question 10

Estuarine invertabrates

Arenicola marina

Answer 10

Lugworm

non-selective deposit feeder - consumes sediment, poops out what isn’t beneficial

Question 11

estuarine invertebrates

Macoma balthica

Answer 11

Baltic tellin

filter feeder at high tide, deposit feeder at low tide

Question 12

estuarine invertebrates

Nevels diversicola

Answer 12

ragworm

hunter/predator of other invertebrates

Question 13

What plants can protect estuaries from a 3.3ml/yr sea level rise?

Answer 13

Cordgrass - stabilises sediments