Aquatic Ecology

Saltwater (Marine) Ecosystems

Ocean:

•estuaries & coastal wetlands

•barrier islands

•coral reefs

•mangroves

Freshwater Ecosystems

•lakes

•rivers & streams

•wetlands

Marine Ecosystems

Economic Services

Climate moderation Food

CO2 absorption Animal and pet feed

Nutrient cycling Pharmaceuticals

Harbors and transportation routes

Waste treatment

Reduced storm impact (mangroves, barrier islands, coastal wetlands)

Coastal habitats for humans

RecreationHabitats and nursery areas Employment

Genetic resources and biodiversity

Oil and natural gas

Minerals

Scientific information Building materials

Ecological Services

NATURAL CAPITAL

Factors Affecting Aquatic Ecosystems• Light (solar radiation)

decreases with depth because of absorption by water, suspended materials, & phytoplankton; essential for photosynthesis

Turbidity (cloudiness) effects light

• Temperaturedecreases with depth because of decreasing energy input from sun; affects dissolved gases, rates of chemical reactions, & where organisms can live;

•Dissolved oxygen- factors that affect DO

• Temperature – less dissolved gasses at warmer temperatures.

• Rate of production through photosynthesis

• Rate of consumption through cellular respiration

• Pressure

•Nutrient availability most limiting macronutrients are phosphorus (P) & nitrogen (N); limiting micronutrients include iron (Fe); essential for growth of phytoplankton.

Factors Affecting Aquatic Ecosystems Cont.

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)

Changes in Temp., O, & N with Depth in Ocean

Nitrate Concentrations High concentrations of nitrates found in areas of:

• low productivity (in areas of high productivity- nutrients are quickly utilized by living things)•High upwellings- upwellings bring cold, nutrient rich H2O

How do areas of high nitrates along coast of South America relate to weather unit?

Surface Ocean Topography• Created by prevailing wind directions and ocean temperature

Life zones of the OceanVertical Zones:

Euphotic Zone: 0 - 200 mGreatest amount of light.

(Eu = good, photo = light)

Bathyl Zone: 200 - 4500 m

Abyssal Zone: 4500 - 11,000“marine snow” – dead organisms from above(Abyss= the deep)

Hadal Zone: > 6000m

Benthic Zone = Region along bottom of sea

Benthos = bottom dwelling sea creature.

Pelagic Zone = open seaRegion that is not near the shore or close to the bottom.

• extends from high–tide mark to edge of continental shelf

• entirely within the euphotic zone & includes estuaries, wetlands, mangroves, barrier islands, & coral reefs

•nutrient–rich & the site of most commercial fisheries•high primary productivity: sunlight + nutrients from land & ocean currents

Coastal Zone of the Ocean

Importance

•nutrient rich and high primary productivity

•nurseries for fish & other aquatic animals

•waterfowl & shorebird breeding areas

• filter water pollutants

Estuaries & Coastal WetlandsEstuary: where seawater mixes with freshwater from land, generally at the mouth of a river

Coastal wetland: areas of coastal land covered all or part of the year with salt water

Brackish= mix of salt water and fresh

Human Impacts

Estuaries & Coastal Wetlands

• world has lost over half of its estuaries & coastal wetlands

• percentage lost in the U.S. even higher. Most lost to coastal development

• causes of degradation: urban runoff, sewage treatment plant effluent, sediment & chemical runoff from agricultural lands

Barrier Islands: long, thin, low offshore islands of sand that run parallel to the shore. They do not remain stationary over time.

Importance

•protect mainland from offshore storms

•shelter inland bays, estuaries, & wetlands

Barrier Islands

Human Impacts• Development on barrier islands

– destroys dunes & dune

vegetation

– causes beach erosion

(through trying to keep

islands in place)

– destroys or disturbs wildlife habitat (e.g., some endangered birds nest on barrier islands)

Protecting barrier islands– jetties & seawalls

– beach replenishment

– replanting dune vegetation, controlling development

Barrier Islands

Ocean City, MD

• reefs formed by mutualism between polyps & algae

• reefs built as colonies of polyps secrete limestone; hard deposits remain when the polyps die

• reefs located in coastal zones of tropical oceans

Coral Reefs

Importance

• high biodiversity: “tropical rain forests of the ocean”

• protect coastlines from storms & high waves

• nurseries for many fish species

• disappearing

Coral Reefs

Vulnerability

• slow growing

• easily disturbed

• thrive only in clear water

Human Impacts

• sediment runoff & effluent

• increased UV radiation (ozone depletion)

• fishing with cyanide & dynamite

Mangrove Swamps• Salt-tolerant trees & shrubs • Warm tropical coastal areas• Too silty for coral reefs

• Protect coastlines from erosion, especially during typhoons & floods• Trap nutrient-rich sediments• Provide habitat for fish, birds, invertebrates, and plants

NATURAL CAPITAL

Freshwater Systems

Ecological Services

Economic Services

Climate moderation Food

Nutrient cyclingDrinking water

Waste treatmentIrrigation water

Flood control

HydroelectricityGroundwater recharge

Habitats for many species

Transportation corridors

Genetic resources and biodiversity

Recreation

Scientific information Employment

Lakes

Littoral zone: shallow area near the shore, to the depth at which rooted plants stop growing.

Limnetic zone: open, sunlit, surface layer away from the shore. Depth is the limit of light penetration.

Profundal zone: deep, open water where there is no light penetration.

Benthic zone: the bottom of a lake; inhabited by insect larvae, decomposers, & clams.

Freshwater Ecosystems

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

Thermal stratification:

during summer

(temperate lakes)

•epilimnion: warm, upper layer of water

•thermocline: zone of lake where temperature changes rapidly with depth

•hypolimnion: colder, denser lower layer of water can be depleted of oxygen in eutrophic lakes

LAKES

Overturn: spring & fall (temperate zone lakes)

•upper layer of water cools and sinks,

•winds mix layers

•redistributes oxygen & temperature evenly

•redistributes nutrients from the lower layers

LAKES

Watershed: the land area that delivers water, sediment, & dissolved substances to a water body.

Zones

• source zone: cold, clear, fast–running streams in upper watershed (headwaters)

• transition zone: middle part of watershed, where streams widens & join, flow slows, water temperature increases

• flood plain zone: many streams join to form a broad, slow–moving, meandering river in lower watershed

Streams & Rivers

Waterfall

LakeGlacierRain and

snowRapids

Source Zone

Transition Zone

Tributary

Flood plainOxbow lake

Salt marsh

Delta Deposited sediment

Ocean

WaterSediment

Floodplain Zone

Riparian Zone is the zone along a stream or river.

WetlandsLands covered with fresh water all or part of the time (excluding lakes).

Wetland functions

• wildlife habitat, especially for waterfowl & amphibians

• filter sediments & pollutants from runoff , “nature’s kidneys”

• flood attenuation

Human impacts:

• some states have lost over 90% of their wetlands by filling or draining.