Aquatic habitats

Question 1

3 types of aquatic habitats

Answer 1

marine
riverine
lacustrine

Question 2

Aquatic habitats variations

Answer 2

• Transitional
• Standing-water (lentic) (lake)
• Flowing-water (lotic) (river)
• Estuarine (brackish)

Question 3

Aquatic habitats uses

Answer 3

• Reproductive
• Feeding
• Cover

Question 4

How to classify aquatic habitats

Answer 4

1. Wetland vs Deep water
2. Major classes divided based on water salinity
3. subsystems based on physical characteristics (bottom type, vegetation, etc)

Question 5

water salinity types

Answer 5

Marine – saltwater
Estuarine – Brackish

Riverine,
Lacustrine, – Freshwater
Palustrine(wet lands)

Question 6

Transitional habitats

Answer 6

Located between 2 habitat types
palastrine ( Marshes,Bogs,Swamps ie wetlands) Freshwater- freshwater

Estuaries freshwater-marine

Question 7

WETLANDS characterized by:

Answer 7

• Presence of water at least sometimes (can dry up)
• hydric plants: water loving plants (e.g., cattails, cordgrass)
• hydric soils (humic – high in decomposing plants matter and sphagnum or peat – good preservatives)
  -Occur where water table is at the land surface or close to it.

Question 8

Palustrine habitat Critically important for(5):

Answer 8

• Aquatic and terrestrial species habitat
• Flood water retention & groundwater recharge
• Nutrient recycling
• Water purification
• Microclimate modification

Question 9

Marshes:

Answer 9

Low, treeless wet areas characterized by sedges,
rushes, and cattails
• Fish and fishless varieties
• Important to waterbirds migration (e.g., ducks, egrets, terns,..)

Question 10

Bogs:

Answer 10

• Wet areas characterised by spongy mats of vegetation
• Sphagnum or peat mosses and heaths

Question 11

Swamps:

Answer 11

• Wet areas usually containing standing tree

Question 12

Lentic (standing water) habitat types

Answer 12

Natural Lakes, ponds, and reservoirs

Question 13

Lentic (standing water) input/outputs

Answer 13

• Currents can occur in the form of:
- Groundwater / river inputs/outputs
- Wind action/upwellings
- Underwater wateralls

Question 14

Why does hot water stay on surface

Answer 14

cold water flowing to bottom of a lake because of different densities; causes flow

Question 15

Natural lakes:

Answer 15

No universally applied criteria
Ponds Smaller!
Lakes Bigger!
• Lakes typically deep enough to thermally stratify,

Question 16

thermal stratification

Answer 16

you can form different habitats within a lake if its deep enough based on densities

Question 17

Human-made water bodies – impoundments

Answer 17

• Blocked or captured natural waterways or sources –
with some size specification outlining types

• Ponds: < 10 hectares (dugouts, gravel pits farm ponds)
• Intermediate impoundments: 10-200 hectares (flood control, small scale industrial)
• Large impoundments/Reservoirs: > 200 hectares (Flood control, large scale industrial)

Question 18

Lentic habitat zones

Answer 18

Littoral zone: Plants can grow
Benthic zone: entire bottom of habitat
Profundal and Aphoric zone: sun does not reach, no phytoplankton/significantly less
Limnetic zone: where sun reaches (top)

Question 19

Lentic habitat stratification

Answer 19

exhibit zones defined by water temperature

Generally warm water floats on colder water
• More different water temperatures harder to mix
• Can cause stratification (good for biodiversity)

greater the difference between water temperature, harder/more energy costly it is for them to mix. generally hot water will float on cold water.

Question 20

When is water densest

Answer 20

4ºC

Question 21

Stratification and seasonal change

Answer 21

Spring overturn (4ºC)
Summer stratification (warm on surface, cold on bottom)
Fall overturn (10ºC)
Winter Reverse stratification (Ice, 1ºC, then 4ºC)

• Establishes a very clear seasonal change in habitat defining growing season and overwintering period for most aquatic organisms (can be traced in scales and otoliths)
• Not all lentic systems stratify!

Question 22

Lentic habitat productivity

Answer 22

Lentic habitats can also be categorised based on productivity
• Lentic habitats can vary from low to high productivity, sometimes within the
same system (i.e., eutrophic dead zones)
• Key elements for production are [P] and [N]

Question 23

Eutrophication

Answer 23

surplus of nutrients being inputed (nitrogen and phosphate) often from farming. this is a s this causes huge algal blooms

a lot of plankton etc, they die, sink to bottom, decompose taking all o2, removing o2 from water, everything else dies

Question 24

Lotic habitats Characteristics

Answer 24

Riverine systems exhibiting directional flow and range in size from small streams to large rivers connecting lakes and draining to oceans
• Can have ephemeral, intermittent to permanent flows
• Can flow rapidly or have slow meander
• Habitat is much more dynamic than in lentic habitats

Question 25

Lotic habitats – stream order

Answer 25

stream orders related to how much flow and if you can see the flow on a topographic scale.
Stream order used to classify river/stream systems
Stream order number also proportional to water discharge and watershed area

Stream order 2 (SO2): Where two SO1s meet etc,.

Question 26

Lotic habitats – variability

Answer 26

• Length,
• Area,
• Bottom type, - Many others
• Width,
• Flow volume,
• depth,
• water temperature
  • Typically, more uniform in terms of water characteristics than lentic systems because the water is constantly moving and mixing (e.g., Temperature, DO, pH)

• Nutrients and minerals essential for production often washed away and so tend to be less productive than lentic environments.

Question 27

Lotic habitats –4 types

Answer 27

Riffles: Shallow narrow areas with faster flow and rocky bottoms because smaller particles swept downstream

Runs: Fastest portions of rivers and streams (rapids, and chutes occur here)

Pools: Wider and deeper with much slower current and where sediment accumulates. This creates a soft bottom with deep sediments

Backwater areas: Side channels connected, but not in strong current (almost like lentic systems)

Question 28

Are species connectivity among population higher or lower in lotic habitats?

Answer 28

expect more in a lentic than loic since rivers have more barriers ie cannot connect unlike in lakes.

Question 29

Estuarine habitats

Answer 29

Where freshwaters enter the ocean
• Transitional habitats (sometimes coastal wetlands)
• Can be small river to large bay type entries (Chesapeake Bay) • Important feeding/nursery habitats for aquatic species
• Important natural buffers from oceanic processes (floods, storms, erosion etc,..)
• Threatened by human pollution and development

Question 30

Estuarine – salinity flux

Answer 30

dependent on tides and seasons
• Brackish waters (mixes of salty sea and freshwaters)
• Can have intense salinity gradients called salt wedge

WHY DOES GRADIENT FORM?
• Heavy (dense sea water incursions under lighter freshwaters –> creates chemocline)
• Transient (moves), but brings in lots of nutrients
• Unique set of species adapted to these transitions zones

this accumulates a lot of plankton/food sources/production

Question 31

Required (essential) habitats

Answer 31

Reproductive habitat:
• Critical for species survival in areas (involves vegetation, rocks, logs,
sand/gravel)

•Cover habitat (escape/resting ): Important shelters to weather elements(temperature,density), concealment or escape from predators (coral,rocks)

Feeding habitat :to help species grow maintain population and abundance levels ,can be temporary or permanent, vegetation

Question 32

Three temperature layers in stratification

Answer 32

epilimnion (surface level, warm)
thermcline (middle layer, transition zone)
hypolimnion (bottom layer, cold)