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