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MAR 333 - Unit 2 > Unit 2 - Estuarine Ecology > Flashcards

Unit 2 - Estuarine Ecology Flashcards

1
Q

What are estuaries?

A

semi-enclosed bodies of water where freshwater from rivers mixes with seawater

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2
Q

What do estuaries originate as?

A

Drowned river valleys, Fjords, Bar-built estuaries, Tectonic estuaries

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3
Q

What is the most common origin and setting of estuaries?

A

Drowning of the mouth of a river valley.

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4
Q

What is the origin of estuaries in high latitudes?

A

glaciers have carved deep, narrow, steep-walled valleys, and many have glacial moraines.

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5
Q

How do bar-built estuaries evolve?

A

spit extension across an embayment.

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6
Q

How do tectonic estuaries commonly result?

A

block faulting

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7
Q

What are the three types of estuaries based on the relative importance of river inflow and tidal mixing?

A

Salt-wedge estuaries, partially mixed estuaries, well-mixed estuaries

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8
Q

What happens in salt-wedge estuaries based on river inflow and tidal mixing?

A

dominated by river outflow, stratified with halocline

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9
Q

What happens in well-mixed estuaries based on river inflow and tidal mixing?

A

Tidal turbulence destroys halocline and water stratification

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10
Q

What causes varying conditions within an estuary?

A

River discharge and tidal flow

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11
Q

How can an estuary become well-mixed?

A

when river flow decreases relative to tidal mixing

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12
Q

When can an estuary temporarily become salt wedge?

A

times of maximum river discharge, usually during spring snowmelt

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13
Q

How are estuaries defined?

A

mixing characteristics between freshwater and seawater inputs

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14
Q

What type of currents characterize salt-wedge estuaries?

A

a net landward-directed bottom current and a net seaward-directed surface current

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15
Q

What type of currents characterize partially mixed estuaries?

A

strong currents,with net landward-flowing bottom currents andnet seaward-flowing surface currents

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16
Q

What type of currents characterize well-mixed estuaries?

A

net currents that are landward-directed at all depths on one side of the estuary and seaward-directed flow at all depths on the other

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17
Q

Why is species diversity low in estuaries?

A

Stressful conditions and abundant nutrients responsible; best adapted organisms dominate their ecological niche.

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18
Q

What factors contribute to the low number of species in estuaries?

A

Widely fluctuating environmental conditions, abundant nutrients, and competition among organisms

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19
Q

How often do phytoplankton blooms occur in estuaries?

A

Despite abundance of nutrients, phytoplankton blooms are irregular.

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20
Q

What commonly forms the base of the food chain in estuaries?

A

Detritus washed in from adjacent salt marshes

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21
Q

What do benthic fauna in estuaries reflect?

A

the nature of the substrate.

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22
Q

How do juvenile fish utilize estuaries?

A

Juvenile fish live in estuaries before maturing and migrating to the ocean.

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23
Q

How do estuaries assist in trade?

A

efficient, overseas transportation of goods, agriculture and oil

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24
Q

What food do we get from Estuaries?

A

crabs, clams, fish

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25
Q

What habitats do we get from estuaries?

A

fish “nursery” areas, waterfowl

26
Q

How are Estuaries Threatened?

A

Pollutants, Nutrients and eutrophication, Shoreline development, Habitat loss, Mariculture, Overharvesting, Invasive species transported in ballast water

27
Q

What are lagoons?

A

Shallow bodies of coastal water that receive little to no freshwater inflow.

28
Q

How do lagoons vary in salinity?

A

from brackish (mixed with freshwater) to hypersaline (extremely salty), depending on climate and local hydrology.

29
Q

Where can lagoons occur?

A

at any latitude and range from completely isolated to semi-enclosed.

30
Q

What are the typical bottom sediments in lagoons?

A

Sand or mud eroded from shoreline or swept in through tidal inlet

31
Q

What is the characteristic of the water column in lagoons in the tropics?

A

typically isothermal

32
Q

How does salinity generally change in lagoons in the subtropics away from the inlet?

A

increases; may induce inverse flow

33
Q

Where are salt marshes commonly found?

A

areas protected from high-energy waves, winds, or currents like the landward side of barrier islands.

34
Q

What happens to salt marshes daily at high tide?

A

They flood, then drain through channels w/ ebb tide.

35
Q

Why are salt marshes considered productive environments?

A

They are one of the most productive environments on Earth.

36
Q

What type of environment do salt marshes grow in?

A

Muds and sands sheltered by barrier islands

37
Q

How are salt marshes classified based on topography and plant assemblages?

A

As low or high marshes

38
Q

What are the two parts of salt marshes?

A

Low salt marsh and high salt marsh

39
Q

How are salt marshes often characterized in terms of vegetation?

A

By dominant grasses with different degrees of salt tolerance

40
Q

What factors strongly influence the distribution and density of organisms in salt marshes?

A

Availability of food, need for protection, frequency of flooding

41
Q

How do mussels contribute to the ecosystem in marshes?

A

fertilize sediments and helps stabilize them

42
Q

What role do fiddler crabs play in marsh ecosystems?

A

Burrowing oxygenates sediments, consumption of organic matter helps cycle nutrients back into the marsh

43
Q

How do plants benefit animals in marsh ecosystems?

A

protection from predation and buffer from potential physical stresses

44
Q

What is a prominent feature of a salt marsh?

A

Pannes

45
Q

What are pannes?

A

Small, isolated pools of water occurring in areas of low elevation

46
Q

How are pannes formed?

A

when surface layers of organic debris are decomposed by bacteria…..high tides and runoff water fill pannes

47
Q

How do large vascular plants modify salt marsh habitats?

A

They stabilize and trap sediment, buffer waves and currents, and oxygenate the sediments.

48
Q

What role do large vascular plants play in salt marsh habitats?

A

make habitat more habitable to other plants and animals

49
Q

What does salt marsh evolution record?

A

interaction between river input and coastal ocean, including SLR.

50
Q

What dominates the youthful stage of salt marsh evolution?

A

Low marsh.

51
Q

When is the stage of mature development reached in salt marsh evolution?

A

When about one-half of the salt marsh consists of high marsh.

52
Q

What causes more vertical growth of the marsh surface in salt marsh evolution?

A

Additional deposition of sediment.

53
Q

What is the final stage of salt marsh evolution where the entire wetland is high marsh?

A

Old marsh.

54
Q

What does the position and character of a salt marsh reflect?

A

Retreat or advance of the ocean/river interface

55
Q

How does longshore drift of sand protect a cove?

A

From direct wave attack

56
Q

What happened by 400 B.C. in relation to the salt marsh evolution?

A

The spit had elongated considerably, and high marsh had extended into the bay covering older low-marsh deposits

57
Q

What has continued to happen in the salt marsh evolution up to the present?

A

Spit growth, mud deposition, vertical growth of wetlands resulting in dominantly high-marsh communities

58
Q

What is the stage known as ‘old marsh’ in the salt marsh evolution?

A

Dominantly high-marsh communities resulting from mud deposition and vertical growth of wetlands

59
Q

What does a sediment core show?

A

The stages of marsh development

60
Q

HUMAN IMPACTS

A

Rotary Ditching, Marsh Impoundment, Eutrophication, Restoration, Introduced Species

MAR 333 - Unit 2 (8 decks)

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