Lecture 1

Question 1

What are the three zones in aquatic environ meets?

Answer 1

Pelagic zone
Benthic zone
Littoral zone ( Rocky and non rocky)

Question 2

What is the pelagic zone?

Answer 2

Open water eg. Overlying water inrivers/ open water in lakes • open ocean (not coastal regions)

Question 3

What two type of organisms in habit the pelagic zone? Ts. e

Answer 3

Pelagic and nektonic

Question 4

Where do planktonic organisms live?

Answer 4

In the pelagic zone/ open water

Question 5

What are

Nektonic organisms?

Answer 5

Organisms that actively swim in the water column

Question 6

What are Pelagic organisms?

Answer 6

Ones that float within the water column

Question 7

Describe organisms in the benthic zone?

Answer 7

They dwell on the bottom of the water body, often in mud or on rocks

Question 8

What are the two types of benthic organisms

Answer 8

Epifaunal , infaunal

Question 9

What’s the difference between infaunal and epifaunal organisms

Answer 9

Ipifaunal-Living within the sediment the sediment or substrate

Epifaunal- living onto of the sediment or substrate

Question 10

What is the difference between lotic and lentic waters?

Answer 10

Lotic-Running waters

Lentic- still waters

Question 11

What is the density of 1cm cubed of water

Answer 11

1g

Question 12

How does the viscosity of water benefit aquatic plants?i

Answer 12

The don’t need to put energy into building vascular tissues for stability
They can place more energy into reproductive processes,giving faster rates of reproduction in comparison to terrestrial plants

Question 13

How does temperature relate to water stability?

Answer 13

Water has a high heat capacity at one calorie per gram, whereas waters is lower. This makes air temperatures more variable, and waters less- providing increased stability for organisms

Question 14

When is water at its densest?

Answer 14

3.94 degrees Celsius
1ml equals 1g in freshwater
1ml equals 1.026g

Question 15

Why is sea water denser that freshwater at 3.94 degrees Celsius?

Answer 15

The salt content

Question 16

What temperatures do fresh and sea water freeze at?

Answer 16

Sea water:-2

Freshwater:0

Question 17

What is a homothermal environment

Answer 17

Organisms can exist anywhere within the water body due to effective mixing of the water column

Question 18

Explain the vertical structure of the water column in water bodies less than 3m in depth. Eg. Shallow seas, rivers,estuaries, coastal waters

Answer 18

The sun heats the water column, and convection occurs.

The water body is effectively mixed, forming a homothermal environment

Question 19

Explain the mixing regime in water bodies greater than 3m in depth

Answer 19

Warm water is heated by the sun and lighter than cold water. Mixing is ineffective, meaning that there’s no distribution of temperature throughout the water body and STRATIFICATION occurs

Question 20

What does the lake split into during stratification?

Answer 20

Epilimnion-the upper lake surface with warm water

Hypeolimnion-lower surface of the stratified system

Question 21

Why do organisms congregate at the thermocline?

Answer 21

Conditions in the epilimnion and hypo lim ion are too hot and cold respectively, and there’s high nutrient diffusion upwelling from the colder regions(nitrogen and phosphorous)

Question 22

What are the three main types of stratification?define them

Answer 22

Holomictic stratification- no stratifying occurs
Monomictic- stratifies once a year, in summer (eg deep lakes)
Amictic- system is permanently stratified

Question 23

Why is lots of biological activity concentrated at depths from the top to 200 m in oceans?

Answer 23

The epilmnion is at depths of 200m in oceans, so this doesn’t occur s above it (water at greater depths is hotter)

Question 24

Why is the thermocline the ideal position for food webs?

Answer 24

Nutrients up well from the hypolimnion