Lecture 1 Flashcards
What are the three zones in aquatic environ meets?
Pelagic zone
Benthic zone
Littoral zone ( Rocky and non rocky)
What is the pelagic zone?
Open water eg. Overlying water inrivers/ open water in lakes • open ocean (not coastal regions)
What two type of organisms in habit the pelagic zone? Ts. e
Pelagic and nektonic
Where do planktonic organisms live?
In the pelagic zone/ open water
What are
Nektonic organisms?
Organisms that actively swim in the water column
What are Pelagic organisms?
Ones that float within the water column
Describe organisms in the benthic zone?
They dwell on the bottom of the water body, often in mud or on rocks
What are the two types of benthic organisms
Epifaunal , infaunal
What’s the difference between infaunal and epifaunal organisms
Ipifaunal-Living within the sediment the sediment or substrate
Epifaunal- living onto of the sediment or substrate
What is the difference between lotic and lentic waters?
Lotic-Running waters
Lentic- still waters
What is the density of 1cm cubed of water
1g
How does the viscosity of water benefit aquatic plants?i
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
How does temperature relate to water stability?
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
When is water at its densest?
3.94 degrees Celsius
1ml equals 1g in freshwater
1ml equals 1.026g
Why is sea water denser that freshwater at 3.94 degrees Celsius?
The salt content
What temperatures do fresh and sea water freeze at?
Sea water:-2
Freshwater:0
What is a homothermal environment
Organisms can exist anywhere within the water body due to effective mixing of the water column
Explain the vertical structure of the water column in water bodies less than 3m in depth. Eg. Shallow seas, rivers,estuaries, coastal waters
The sun heats the water column, and convection occurs.
The water body is effectively mixed, forming a homothermal environment
Explain the mixing regime in water bodies greater than 3m in depth
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
What does the lake split into during stratification?
Epilimnion-the upper lake surface with warm water
Hypeolimnion-lower surface of the stratified system
Why do organisms congregate at the thermocline?
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)
What are the three main types of stratification?define them
Holomictic stratification- no stratifying occurs
Monomictic- stratifies once a year, in summer (eg deep lakes)
Amictic- system is permanently stratified
Why is lots of biological activity concentrated at depths from the top to 200 m in oceans?
The epilmnion is at depths of 200m in oceans, so this doesn’t occur s above it (water at greater depths is hotter)
Why is the thermocline the ideal position for food webs?
Nutrients up well from the hypolimnion
