Ch 06 Aquatic/ Salt Water

Sec 01Section 02

A. AQUATIC ENVIRONMENTS

1. Saltwater and freshwater aquatic life zones cover almost three-fourths of the earth’s surface

Figure 6-2Figure 6-2

2. Salinity of the water determines the major types of organisms found in an aquatic environment

3. There are four major types of organisms in aquatic systems

a) Plankton are weakly swimming, generally one-celled organisms. There are three types of plankton

o phytoplankton : plant planktono zooplankton : animal plankton single-celled to

large invertebrates such as jellyfisho ultraplankton : are photosynthetic bacteria

Plankton

PLAYYOUTUBE VIDEO

b) Ultraplankton may be responsible for as much as 70% of the primary productivity

c) Nekton is a second group of organisms, such as fish, turtles and whales

d) Benthos are bottom dwellers, such as, barnacles, oysters, worms, lobsters and crabs.

e) Decomposers are a fourth group

4. Life in most aquatic systems is found in surface, middle, and bottom layers.

5. Temperature, access to sunlight for photosynthesis, dissolved oxygen content, nutrient availability changes with depth.

a) Euphotic zone (upper layer in deep water habitats): sunlight can penetrate.

b) O2 levels are lower in deeper, dark layers c) Open oceans tend to have limited nutrients

that limit productivity.

Animation: Ocean Provinces

PLAYANIMATION

B. SALTWATER LIFE ZONES

1. Oceans have two major life zones: the coastal zone and the open sea

2. The coastal zone interacts with the land

3. Coastal zones have a high net primary productivity (NPP)

a) They constitute 10% of the oceans and contain 90% of all marine species

Fig. 6-5, p. 130

Dar

knes

sTw

iligh

tPh

otos

ynth

esis

Sun

Continental shelf

Estuarine Zone

High tide

Low tide

Coastal Zone

Bathyal Zone

Euphotic Zone

Abyssal Zone

Sea level

Open Sea

PLAYANIMATION

4. There is ample sunlight and nutrients flow from land and wind/currents

5. The coastal zone extends from the high-tide mark on land to the edge of the continental shelf

a) Provides numerous ecological and economic services.

b) Subject to human disturbance

Marine Ecosystems

6. Scientists estimate that marine systems provide $21 trillion in goods and services per year – 70% more than terrestrial ecosystems.

Figure 6-4Figure 6-4

Fig. 6-6, p. 130

Estuaries and Coastal Wetlands: Centers of Productivity

7. Estuaries include river mouths, inlets, bays, sounds, salt marshes in temperate zones and mangrove forests in tropical zones.

Figure 6-7Figure 6-7

EstuariesEstuaries

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8. Estuaries and coastal marshes provide ecological and economic services.

a) Filter toxic pollutants, excess plant nutrients, sediments, and other pollutants.

b) Reduce storm damage by absorbing waves and storing excess water produced by storms and tsunamis.

c) Provide food, habitats and nursery sites for many aquatic species.

Mangrove Forests

9. Are found along about 70% of gently sloping sandy and silty coastlines in tropical and subtropical regions.

10. Organisms living in the intertidal zone have adapted ways to survive the daily changes in wet/dry conditions, and changes in salinity

a) Temperature, Salinity, Wave action

Figure 6-8Figure 6-8

TIDEPOOLSSea star Hermit crab Shore crab

AnemoneSea urchin

Sculpin

Nudibranch

Low tide

Monterey flatworm

Kelp Sea lettuce

Barnacles

Mussel

Periwinkle

High tide

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Fig. 6-9, p. 132

Barrier Beach

Peanut worm

Beach flea

TigerBeetle

DwarfOlive

Clam

High tide

GhostShrimpMole

Shrimp

Sandpiper

Moon snail

Sand dollarWhite sand macoma

Blue crab

Low tideSilversides

Barrier Islands

11. Low, narrow, sandy islands that form offshore from a coastline.

12. Primary and secondary dunes on gently sloping sandy barrier beaches protect land from erosion by the sea.

Figure 6-10Figure 6-10

Ocean City, Maryland

13. Threats to Coral Reefs:Increasing Stresses

a) Biologically diverse and productive coral reefs are being stressed by human activities.

Figure 6-11Figure 6-11

PLAYYOUTUBE VIDEO

b) The ideal water temperature is between 18-30oC and will bleach if the water warms above this by so much as 1oC

c) Severe storms, freshwater floods, and invasions of predatory fish adversely affect the reefs

d) There are indications that recovery is possible when restrictions are imposed and pollution is reduced.

14. Biological Zones in the Open Sea:Light Rules

a) Euphotic zone: brightly lit surface layer. Nutrient levels low, dissolved O2 high, photosynthetic

activity from phytoplankton.

b) Bathyal zone: dimly lit middle layer. No photosynthetic activity, zooplankton and fish live

there and migrate to euphotic zone to feed at night.

c) Abyssal zone: dark bottom layer. Very cold, little dissolved O2.