VIII - Aquatic Ecology

Question 1

Factors Affecting Life in Aquatic Ecosystems

Answer 1

Temperature
Solar radiation
Dissolved oxygen
Nutrient Availability

Question 2

Temperature

Answer 2

decreases with depth because of decreasing energy

input from sun; affects dissolved gases, rates of chemical reactions, & where organisms can live

Question 3

Solar radiation

Answer 3

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

Question 4

Dissolved oxygen

Answer 4

varies with temperature, producers, & consumers;

essential for respiration of organisms

Question 5

Nutrient Availability

Answer 5

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

Question 6

Characteristics of Oceans

Answer 6

• cover 71% of the earth’s surface
• ocean currents distribute solar heat
• reservoir for carbon dioxide (CO2)
• regulates temperature of the
troposphere
• habitat for plants & animals, including critical food sources
for humans
• communal dumping ground

Question 7

Life zones of ocean

Answer 7

Euphotic zone
Bathyl zone
Abyssal zone

Question 8

zones defined

by amount of

Answer 8

solar radiation
penetrating
the water

Question 9

Coastal Zone of the Ocean

Answer 9

High tide mark to edge of continental shelf
Within euphotic zone
Nutrient rich
Site of most commercial fisheries
High primary productivity

Question 10

The coastal zone includes

Answer 10

estuaries
wetlands
barrier islands
coral reefs

Question 11

Estuary

Answer 11

where
seawater mixes
with freshwater
from land,
generally at the
mouth of a river

Question 12

Coastal wetland

Answer 12

where 
seawater mixes
with freshwater
from land,
generally at the
mouth of a river

Question 13

Importance of estuaries & coastal wetlands

Answer 13

• nutrient rich
• high primary
productivity
• nurseries for fish
& other aquatic
animals
• waterfowl &
shorebird
breeding areas
• filter water
pollutants

Question 14

Human Impacts of estuaries & coastal wetlands

Answer 14

• world has lost over half
of its estuaries &
coastal wetlands
• percentage lost in the
U.S. even higher most
lost to coastal
development

Question 15

Causes of degradation of estuaries & coastal wetlands

Answer 15

urban runoff, sewage
treatment plant effluent, sediment & chemical
runoff from agricultural
lands

Question 16

Barrier Islands

Answer 16

long, thin, low offshore islands of sand that run

parallel to the shore.

Question 17

Barrier Islands Importance

Answer 17

• protect mainland
from offshore
storms
• shelter inland bays,
estuaries, &
wetlands
• popular
recreational &
residential areas

Question 18

Human Impacts of Barrier Islands

Answer 18

Development of barrier islands
Destroys dunes & vegetation
Causes beach erosion
destroys & disturbs wildlife habitat

Question 19

Primary Dune

Answer 19

No direct passage or building

Question 20

Back Dune

Answer 20

Most suitable for development

Question 21

Beach

Answer 21

Intensive recreation

No building

Question 22

Trough

Answer 22

Limited recreation & walkways

Question 23

Secondary dune

Answer 23

No direct passage & building

Question 24

Bay/ Lagoon

Answer 24

Intensive recreation

Question 25

Sea walls

Answer 25

Protect the cities from beach retreat during natural disaster

Question 26

Beach replenishment

Answer 26

``` Twice a year the Army Corps of Engineers survey our beach to determine the need for any additional sand. ```

Question 27

Replanting Dune Vegetation

Answer 27

Controlling development

Question 28

Coral reefs

Answer 28

Mutualism between polyps & algae Colonies of polyps secrete limestone hard deposits remain when polyps die Located in coastal zones of tropical oceans

Question 29

Importance of coral reefs

Answer 29

High biodiversity Protect coastlines from storms & high waves Nurseries for many fish species Disappearing

Question 30

Vulnerability of coral reefs

Answer 30

Slow growing Easily disturbed Thrive only in clear water

Question 31

Human impacts on coral reefs

Answer 31

``` • sediment runoff & effluent • increased UV radiation • fishing with cyanide & dynamite ```

Question 32

Lakes

Answer 32

standing (lentic) body of freshwater formed when rain, | runoff, or groundwater fills depressions in the landscape

Question 33

Lake zones

Answer 33

Littoral zone Limnetic zone Profundal zone Benthic zone

Question 34

Littoral zone

Answer 34

shallow area near the shore, to the depth at which rooted | plants stop growing

Question 35

Limnetic zone

Answer 35

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

Question 36

Profundal zone

Answer 36

deep, open water where there is no light penetration

Question 37

Benthic zone

Answer 37

the bottom of a lake; inhabited by insect larvae, decomposers, & clams

Question 38

Types of Lakes

Answer 38

Oligotrophic | Eutrophic

Question 39

Oligotrophic

Answer 39

``` – low nutrient supply – low primary productivity – clear water, few plants & fish ```

Question 40

Eutrophic

Answer 40

``` – excess supply of nutrients – high primary productivity – murky water, large phytoplankton population ```

Question 41

Thermal stratification occurs during

Answer 41

Summer in temperate lakes

Question 42

Epilimnion

Answer 42

warm, upper layer | of water

Question 43

Thermocline

Answer 43

zone of lake where temperature changes rapidly with depth

Question 44

Hypolimnion

Answer 44

``` colder, denser lower layer of water can be depleted of oxygen in eutrophic lakes ```

Question 45

Going from surface to bottom, the temperature of a lake

Answer 45

Gradually decreases

Question 46

Going from surface to bottom, the dissolved oxygen concentration of a lake

Answer 46

Epilimnion -> high Thermocline -> medium Hypolimnion -> low

Question 47

Lake overturn occurs during

Answer 47

Spring & fall

Question 48

What happens during overturn?

Answer 48

``` •upper layer of water sinks & winds mix layers •redistributes oxygen & temperature evenly •redistributes nutrients from the lower layers ```

Question 49

Watershed

Answer 49

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

Question 50

Stream zones

Answer 50

Source zone Transition zone Flood plain zone

Question 51

Source zone

Answer 51

cold, clear, fast–running streams in upper watershed

Question 52

Transition zone

Answer 52

``` middle part of watershed, where streams widens & join, flow slows, water temperature increases ```

Question 53

flood plain zone

Answer 53

``` many streams join to form a broad, slow–moving, meandering river in lower watershed ```

Question 54

In source zone common features includes

Answer 54

``` Rain & snow Lake Glacier Rapids Waterfall ```

Question 55

In transition zone common features includes

Answer 55

Tributary | Flood plain

Question 56

In flood plain zone common features includes

Answer 56

``` Oxbow lake Salt marsh Delta Deposited sediment Ocean ```

Question 57

Human impacts on streams & rivers

Answer 57

``` • pollution • sediments • channelization • dams • introduction of exotic species, • removal of vegetation from banks • change of flow (more floods, lower base flow) ```