Aquatic habitats Flashcards
3 types of aquatic habitats
marine
riverine
lacustrine
Aquatic habitats variations
• Transitional
• Standing-water (lentic) (lake)
• Flowing-water (lotic) (river)
• Estuarine (brackish)
Aquatic habitats uses
- Reproductive
- Feeding
- Cover
How to classify aquatic habitats
- Wetland vs Deep water
- Major classes divided based on water salinity
- subsystems based on physical characteristics (bottom type, vegetation, etc)
water salinity types
Marine – saltwater
Estuarine – Brackish
Riverine,
Lacustrine, – Freshwater
Palustrine(wet lands)
Transitional habitats
Located between 2 habitat types
palastrine ( Marshes,Bogs,Swamps ie wetlands) Freshwater- freshwater
Estuaries freshwater-marine
WETLANDS characterized by:
- 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.
Palustrine habitat Critically important for(5):
• Aquatic and terrestrial species habitat
• Flood water retention & groundwater recharge
• Nutrient recycling
• Water purification
• Microclimate modification
Marshes:
Low, treeless wet areas characterized by sedges,
rushes, and cattails
• Fish and fishless varieties
• Important to waterbirds migration (e.g., ducks, egrets, terns,..)
Bogs:
• Wet areas characterised by spongy mats of vegetation
• Sphagnum or peat mosses and heaths
Swamps:
• Wet areas usually containing standing tree
Lentic (standing water) habitat types
Natural Lakes, ponds, and reservoirs
Lentic (standing water) input/outputs
• Currents can occur in the form of:
- Groundwater / river inputs/outputs
- Wind action/upwellings
- Underwater wateralls
Why does hot water stay on surface
cold water flowing to bottom of a lake because of different densities; causes flow
Natural lakes:
No universally applied criteria
Ponds Smaller!
Lakes Bigger!
• Lakes typically deep enough to thermally stratify,
thermal stratification
you can form different habitats within a lake if its deep enough based on densities
Human-made water bodies – impoundments
• 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)
Lentic habitat zones
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)
Lentic habitat stratification
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.
When is water densest
4ºC
Stratification and seasonal change
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!
Lentic habitat productivity
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]
Eutrophication
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
Lotic habitats Characteristics
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