Estuaries

Question 1

Percentage of Salt vs Freshwater?

Answer 1

97.5 vs 2.5

Question 2

When did the Cambrian explosion occur and what was it?

Answer 2

541 MA most major aquatic phyla appear

Question 3

What is a stromatolite and what does it show?

Answer 3

Microbial reefs created by cyanobacteria (layer on top of rock). They are the earliest fossil evidence of life on earth at 3.5 billion years

Question 4

Describe the thermocline pattern in the ocean

Answer 4

Warmer temperature at shallower depths, sharp decrease around 1km

Question 5

Describe the halocline pattern in the ocean

Answer 5

Less saline at shallower depths, sharp increase around 1k

Question 6

Seawater saturation concentration?

Answer 6

35 ppt (can range from 28-41)

Question 7

Describe the pycnocline pattern in the ocean

Answer 7

Matches saline - sharp increase around 1km

Question 8

How do phytoplankton demonstrate physical conditions affecting biology?

Answer 8

They are found in a sharp layer around 50m down where they balance between being warm enough water and still getting nutrient rich upwelling from the bottom.

Question 9

How does wave exposure demonstrate physical conditions affecting biology?

Answer 9

Only stronger swimming larger fish can live in exposed shallow water where the most powerful waves act. In contrast, sheltered areas host a wide variety of fishies

Question 10

How does the decreased availability of dissolved oxygen (as a result of phytoplankton activity) affect biology?

Answer 10

Zooplankton found in this area have adaptations such as large gill area and short diffusion distance from water to blood to be able to extract O2 at low concentrations.

Question 11

Why are estuaries key areas for cities to form?

Answer 11

Offer transport, fresh drinking water, food resources (sheltered environment for fish)

Question 12

Population of australia living on estuaries?

Answer 12

65%

Question 13

Definition of delta

Answer 13

Mouth of the river where sediment deposition occurs

can be both marine and fluvial

Question 14

Two types of waves?

Answer 14

Storm generated - choppy windy

Swell - smooth undulations caused by far out storms

Question 15

How does moon position affect tides?

Answer 15

New moon/Full moon - moon is behind/infront of earth in relation to sun hence STRONG SPRING TIDES
First/Third quarter - Moon is perpendicular to earth hence cancelling out pull of sun so WEAK NEAP TIDES

Question 16

Define: Ebb tide/Flood tide

Answer 16

Movrment of tidal current down/up estuary respectively

Question 17

What are the three classifications of estuary according to its hydrodynamics?

Answer 17

River, wave, tidal

Question 18

What are the four classifications of estuary according to its degree of mixing?

Answer 18

High, Medium, Non, Negatively Stratified
Ranging from a layer of freshwater ontop of Salt (highly) to where extreme evaporation in the river means saltwater is infact moving upstream and resting ontop of river (negatively)

Question 19

Features of tide dominated

Answer 19

Found in North Oz
Mudflats and turbid water
Meandering low energy water
Saltmarshes and Mangroves

Question 20

Features of wave dominated

Answer 20

Found in South Oz
Often forms large sand barriers/bars
Low energy central basin behind - lots of seagrass
Can be open or intermittently open (IOCE) and range from large to small.

Question 21

6 Features measured to define estuary classification?

Answer 21

Entrance channel width
Surface water area
Perimeter
Estuary length
Berm height
Beach width

Question 22

3 physical factors affecting biota in the water

Answer 22

Temperature
Salinity
Sediments

Question 23

Example of an osmoregulator in varying salinity

Answer 23

Salmon fish - changes urine concentration/ion uptake to regulate salinity in cells

Question 24

Example of an osmoconformer in varying salinity

Answer 24

Mangrove plants - have adaptations to withstand high salt levels

• waxy layer reduce water loss
• store salt in vacuole
• limit salt uptake at roots

Question 25

How can behaviour help biota survive extreme salt

Answer 25

Move up and down water column, or if sessile close shell / hide in burrow

Question 26

What is the Northern Pacific Seastar an example of?

Answer 26

An estuarian organism that has a wide temperature/salt range (0-25c/19-41ppt) but reduced when reproducing (5-23c/28-34ppt) It shows how the two variables interact since larvae can survive at 35ppt but ONLY if temp is low

Question 27

What does the Ingles et al paper 2018 with meiofauna show about climate change predictions?

Answer 27

CO2 increase decreases life in the water | Temperature increase increases life in water

Question 28

How does grain size change towards the mouth of the river?

Answer 28

They get bigger, meaning water can drain more easily

Question 29

What is bioturbation and why is it important?

Answer 29

Movement of soils by organisms in the water. This is important as it oxygenates the sediment and avoids anoxic environments.

Question 30

Main 4 habitats present in estuaries

Answer 30

Soft sediments, seagrasses, Mangroves, water column

Question 31

Three categories of infauna?

Answer 31

Macrofauna - >500um (polychaete worms, molluscs, crabs Meiofauna - 62-500um (nematodes, copepods) Microfauna/flora - <62um (bacteria, diatoms)

Question 32

Three types of movement of meio/macrofauna?

Answer 32

1- Moving between grains (small wormlike only) no displacement 2- burrowing by hydrostatic pressure (small polychaetes - use helical muscles in juveniles) 3- burrowing by digging (ghost shrimp)

Question 33

Feeding types (4)

Answer 33

Deposit feeders -> results in bioturbation Suspension feeders - normally sessile can be active (pump) or passive with cilia to catch floating food Predation (some polychaete worms) Scavengers (crabs shrimps gastropods)

Question 34

Why are deposit feeders so special and some examples?

Answer 34

They are environmental engineers extracting what they need from sediment and spitting out the rest. This makes them ecosystem engineers and hence essential for nutrient recycling and irrigation.

Question 35

Features of seagrasses and where they normally grow

Answer 35

shoots n leaves, flowering plant | Needs soft sediment and sheltered water salty!

Question 36

How are they essential to animoos?

Answer 36

Substrate for sessile moos, habitat for motile moos (banjo shark!) especially their juveniles. This is because they baffle water moevment (ecosystem engineers!)

Question 37

Features of mangrove forests

Answer 37

``` Terrestrial halophytes (as opposed to seagrasses that are actual marine grasses) Pneumatophores (ariel roots for gas exchange) and prop roots - essential in waterlogged O2 poor conditions ```

Question 38

Species living in mangroves?

Answer 38

Substrate for seaweed, barnacles, tubeworms, bivalves | Around roots - pulmonate gastropods, burrowing crabs fish

Question 39

What is meant by blue carbon?

Answer 39

Total carbon capture (50% of earths total) by marine organisms. Mostly (50-70%) due to vegetated marine beds - despite only covering <0.5 of surface.