EAES Ch. 7 Aquatic Biodiversity

Aquatic Environments

Limiting factors: Sunlight, temperature, salinity, O2, nutrients CO2, NO3-, PO43-

Coastal (Neritic) Life Zone

• Continental Shelf, ~200m max

• Abundant light, nutrients, O2, mixed by wind / currents

• Most of the life, 90% of Primary Production

Estuaries, Wetlands

• Mixed slat and fresh water (brackish)

• Variable productivity due to temperate, turbidity and human influence (degrades)

• Wetlands can act as pollution filter, and carbon sink

Rocky and sandy shores

• Intertidal zone, higher energy wave environments, light, turbidity, nutrients

• Wet/dry cycles from daily tides, may have higher wave energies

• Intertidal Zone, tidal pools, lagoons

Coral Reefs

• Broad diversity, abundant light, nutrient poor, high productivity

• Affected by ocean acidification, turbidity due to land runoff

• Gradually grow upward with sea-level rise

Open Sea

• Off continental shelf with significant depths 0-11’000m

• Euphotic - lots of light, O2, higher temperature, low nutrients, lower salinity, complex food web

• Bathyal - very low light. lower temperature, higher salinity

• Abyssal / Hadal - no light, nutrient rich, cold, high salinity

Layered Lakes

• Littoral Zone (nearshore): light, nutrients, O2, high diversity, medium primary production

• Limnetic Zone (offshore): light, high primary production, O2

• Profundal Zone: low/no light, no primary production, nekton

• Benthic Zone: lake bottom, low/no light, no primary production, decomposers and detritus feeders

Lake Temperatures

• Epilimnion (warm top), Hypolimnion (cold bottom)

• Temperature changes due to seasons. Top heating during summer, top cooling during winter causes stratification

• Turnover in fall/spring due to Density difference (warm/cold water). Turnover mixes O2 and nutrients

Oligotrophic

• Nutrient poor

• Low Primary Production

• Ex: high mountain lake

Eutrophic

• Nutrient rich

• High primary production

• Lots of life

• May become overly rich due to agricultural runoff

Freshwater stream

• Rainfall on continent

• Storage in snow, ice, lakes, wetlands, groundwater

• Runoff flows downslope towards ocean

Freshwater wetlands

• Form in areas of low slope and abundant water

• Typically in / near river flood plains

• Marsh > Swamp > Fen > Bog