Question for TodayWhat are the different niches that organisms
can occupy in an aquatic ecosystem?How are marine ecosystems organized?How are freshwater systems organized?What are the differences between an
oligotrophic and eutrophic lake?How do humans affect marine and freshwater
ecosystems?
Aquatic life zones and nichesAquatic life zones are similar to terrestrial
biomes.Instead of looking at temperature and
precipitation, aquatic life zones classify by salinity.
Aquatic life zones and nichesTwo major life zones:
Saltwater or marine Oceans Estuaries and coastal wetlands Shorelines, coral reefs and mangrove forests
Freshwater Lakes, rivers, streams and inland wetlands
Aquatic Life Zones and NichesAquatic systems contain floating, drifting,
swimming, bottom-dwelling, and decomposer organisms.Plankton: important group of weakly
swimming, free-floating biota. Phytoplankton (plant), Zooplankton (animal),
Ultraplankton (photosynthetic bacteria)Nekton: fish, turtles, whales.Benthos: bottom dwellers (barnacles, oysters).Decomposers: breakdown organic compounds
(mostly bacteria).
PhytoplanktonDescription – small drifting plantsNiche – they are producers that support most aquatic food chains
Example – cyanobacteria & many types of algae
ZooplanktonDescription – herbivores that feed on
phytoplankton or other zooplanktonNiche – food stock for larger
consumersExample – krill; small crustaceans
NektonDescription – larger, strong-swimming consumers
Niche – top consumers in the aquatic ecosystem
Example – fish, turtles, and whales
BenthosDescription – bottom-dwelling creatures
Niche – primary consumers, decomposers
Example – barnacles, oysters, and lobsters
Marine Life zonesMost Marine Life Zones are organized by
depth/light penetration, and distance from the shore
Three zones based off distance from the shore Intertidal zone, Coastal Zone and the Open Sea
Three Zones based off depth/light penetration Euphotic Zone Bathyal Zone Abyssal Zone
Fig. 8-5, p. 166
Low tideCoastal Zone
Open Sea
Depth in meters
High tideSun
Sea level
50Estuarine Zone
Euphotic Zone 100
Ph
oto
syn
thes
is
Continental shelf
200
Bathyal Zone 500
1,000
Tw
ilig
ht
1,500
Water temperature drops rapidly between the euphotic zone and the abyssal zone in an area called the thermocline .
Abyssal Zone
2,000
3,000
4,000
Dar
knes
s
5,000
10,000
0 5 10 15 20 25 30
0
Water temperature (°C)
Freshwater EcosystemsFreshwater Ecosystems are organized in a
similar way to Marine EcosystemTwo types of Freshwater Ecosystems
Lentic (Standing) Lakes, Ponds, inland wetlands
Lotic (Flowing) Rivers, Streams
LakesLakes are large natural bodies of standing
freshwater formed when precipitation, runoff, or groundwater seepage fills a depressions in earth’s surface.Can be caused by glaciation, crustal
displacement, and volcanic activityLakes are stratified due to Light Penetration
and Temperature.LittoralLimneticProfundalBenthic
Fig. 8-15, p. 175
Sunlight
Painted turtle
Blue-winged teal
Green frog
Muskrat
Pond snail
Littoral zone Plankton
Limnetic zoneProfundal zoneDiving beetle Benthic zone
Northern pike
Yellow perch Bloodworms
Oligotrophic vs. EutrophicEcologist can also classify lakes according to
nutrient content and primary productivity.Two Types:
Oligotrophic Lakes Low Nutrient, Low Productivity Crystal-clear water Small population of phytoplankton and fish.
Eutrophic Lakes High Nutrient, High Productivity High Turbidity, murky-brown or green water
How do Humans affect marine biomes?Major threats to marine systems
Coastal developmentOverfishingRunoff of nonpoint source pollutionPoint source pollutionHabitat destructionIntroduction of invasive speciesClimate change from human activitiesPollution of coastal wetlands and estuaries
How do Humans effect freshwater ecosystem?Impact of dams and canals on rivers
Impact of flood control levees and dikes along rivers
Impact of pollutants from cities and farms on rivers
Impact of drained wetlands