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Aquatic Communities Final Flashcards

1
Q

What are the three general characteristics of lentic systems?

A
  1. Distinct edges
  2. Homogenous bottoms
  3. Well-mixed water
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2
Q

Lentic systems account for ___% of the Earth’s total water.

A

0.016%

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3
Q

What are the 3 most common types of lakes and how are they formed?

A
  1. Tectonic lakes: formed by
    1. Faulting
      • Rift lakes (grabens)
      • Horst lakes
    2. Uplifting of sea floor
      • often shallow
  2. Volcanic lakes
    • Formed within calderas of extinct volcanoes
    • Formed when lava cuts off and dams rivers
  3. Glacial lakes
    • Formed by actions of glaciers (most common type)
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4
Q

What are the 3 types of glacial lakes?

A
  1. Cirque (Tarn) Lakes: formed in a half-open steep-sided hollow at the base of a mountain or valley that was carved out by a glacier.
  2. Valley Lakes:
  3. Kettle Lakes: formed from receding glacial debris
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5
Q

What are 8 types of relatively uncommon lakes?

A
  1. Manmade (resevoirs)
  2. Dammed lakes (both natural and artificial)
  3. Sinkholes
  4. Floodplain lakes (oxbow, levee)
  5. Playa
  6. Dune
  7. Meterorite lakes
  8. Ponds
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6
Q

What are the five zones found in lakes?

A
  1. Littoral: consists of the region where light penetrates to the bottom of the lake to promote photosynthesis
  2. Pelagic: the area of the lake where light cannot penetrate to the bottom
  3. Photic: the part of the lake that recieves enough sunlight to drive photosynthesis
  4. Aphotic: the part of the lake that does not recieve enought sunlight to drive photosynthesis
  5. Profundal: a very cold zone located below the range of effective light penetration
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7
Q

Thermocline

A

The depth at which there is a marked difference in temperature above and below.

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8
Q

Describe the differences between the epilimnion, metalimnion and hypolimnion.

A
  • Epilimnion: the top-most layer in a lake that is warmer and typically higher in pH and dissolved oxygen than the deeper hypolimnion layer. P/R > 1
  • Metalimnion: Also called the thermocline, this is a thin but distinct layer in a large body of fluid in which temperature changes more rapidly with depth than it does in the layers above or below
  • Hypolimnion: the dense, bottom layer of water that is typically the coldest part of a lake in the summer and the warmest during winter. This layer is isolated from wind-mixing during the summer and usually recieves insufficient light to drive photosynthesis. P/R <1
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9
Q

A higher water temperature results in a _____ water density.

A
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10
Q

What are Eutrophic and Oligotrophic lake systems and what physical characteristics define them?

A
  1. Eutrophic: productive
    • Shallow lakes with gently sloping sides. Often unstratified
    • Cultivated, disturbed or naturally fertile watershed.
  2. Oligotrophic: unproductive
    • Deep lakes with steep sides
    • Infertile soils and undisturbed, rocky watersheds.
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11
Q

What are the two lake profiles with regard to dissolved oxygen content?

A
  1. Clinograde Profile: DO is low in the hypolimnion
  2. Orthograde Profile: DO is high in the hypolimnion
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12
Q

What is the distinction in terms of size between micro- and macrozooplankton?

A
  • Macrozooplankton > 200 um
  • Microzooplankton < 200 um
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13
Q

What is the scientific name for cyanobacteria?

A

Cyanobacteria (or blue-green algae) are called Cyanophyta.

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14
Q

What is the scientific name for green algae?

A

Chlorophyta

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15
Q

What is the scientific name for diatoms?

A

Bacillariophyta

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16
Q

What is the scientific name for “golden browns”?

A

Cryptophyta

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17
Q

What is the scientific name for dinoflagellates?

A

Pyrophyta

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18
Q

What are the 3 classes of macrophytes found in the littoral zone?

A
  1. Submergents: photosynthetic parts below the water surface
  2. Floating Plants: photosynthetic parts at the water surface
  3. Emergents: rooted in the water with photosynthetic elements extended above the water surface
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19
Q

What are the 4 seasonal phases of typical lentic systems?

A
  1. Ice Break and Spring Turnover
  2. Onset of Stratification (late spring-summer)
  3. Clearwater Phase
  4. Late Summer (early autumn)
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20
Q

Describe the main features of the ice break and spring turnover phase of lentic systems.

A
  • Deep circulation (isothermal)
  • Light is increasing but low
  • Water is cold
  • Nutrients are high (Si, N and P)
  • Diatoms and small unicellular green algae are dominant
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21
Q

Describe the main features of the “onset of stratification” phase of lentic systems.

A
  • Mixing decreases
  • Light is high and temperature is rising
  • Si in epilimnion decreases
  • Si:P and Si:N ratios decrease
  • Zooplankton increase
  • Edible phytoplankton decrease
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22
Q

Describe the main features of the “clearwater” phase of lentic systems.

A
  • Zooplankton increase
  • Algal populations crash due to grazing
  • Water transparency increases
  • Nutrient saturated growth can occur for a while again, but Si remains low
23
Q

Describe the main features of the “late summer” phase of lentic systems.

A
  • Algae competing at low nutrient levels
  • N and P supplied by zooplankton excretion
  • Higher nutrient patches available to motile algae and storage specialists
  • Cyanobacteria, gelatinous green and dinoflagellates increase

Mixing has the potential to create a secondary bloom

24
Q

What are the 3 basic criteria that all wetlands meet?

A
  1. Hydrophytic vegetation: plants that require or prefer wet soils.
  2. Undrained hydric soils: anoxic soils saturated with water
  3. Wetland hydrology: inundated or wet at least part of the year
25
Q

What does the water table depth determine in wetlands?

A
  1. Whether waterlogging or flooding is seasonal or permanent
  2. The oxygen concentration in the soil
    • Decomposition of organic matter depletes oxygen
    • Decomposition typically slow in the absence of oxygen
    • Leads to the formation of histols or peats
26
Q

Histosols

A

Also called peats, these are typically acidic soils which contain large amounts of organic material derived from decaying organisms.

27
Q

What are the 3 types of wetlands and what criteria define them?

A
  1. Aquatic marginal wetlands: created by rivers and lakes (marshes & swamps)
    • Fringe wetlands: hydrological connection with parent water body
    • Flood wetlands: hydrological separated from parent water body
  2. Mires: fed by groundwater, overland runoff or precipitation
    • Minerotrophic: fens–water and nutrients from groundwater
    • Ombrotrophic: bogs–above groundwater, fed by rainwater
  3. Transitional wetlands: transition between marginal and mire
28
Q

Describe the common features of marshes.

A
  • Dominated by emergent plants
  • Vertical profile: moderate, frequently inundated
  • Soils/Sediments: saturated, mostly anoxic
  • Rich microbial community (bacteria, aufwuchs/periphyton)
29
Q

Describe the common features of swamps.

A
  • Dominated by trees/shrubs
  • Vertical profile: high, usually some standing water
  • Soils/Sediments: saturated, mostly anoxic
  • Less rich microbial community (aufwuchs/periphyton)
30
Q

Describe the common features of bogs.

A
  • Dominated by moss (Sphagnum)
  • Vertical Profile: very low, rain fed, low in nutrients
  • Soils/Sediments: saturated, highly acidic and anoxic, spongy peat
  • Poor microbial community (aufwuchs/periphyton)
31
Q

Describe the common features of fens.

A
  • Dominated by grasses, sedges, rushes and wildflowers
  • Vertical Profile: very low; similar to bogs except fed by groundwater; higher nutrient levels
  • Sediments/Soils: Waterlogged, not as acidic as bogs
  • Poor microbial community (aufwuchs/periphyton)
  • Low temperature, short growing season and water accumulation
32
Q

Coenocline

A

Changes in plant community composition across an envrionmental gradient

33
Q

Describe the 7 wetland zones and which types of plants are found there.

A
  • Zone #1: fully terrestrial environment
  • Zone #2: roots in aerated soil but anoxic/toxic at depth
  • Zones #3-6: species tolerant of permanently waterlogged sediments
    • Z#3: typical aboveground parts are above water
    • Z#4: emergents
    • Z#5-6: floating species and submergents
  • Zone #7: beyond the littoral zone (no attatched macrophytes)
34
Q

Estuary

A

A semi-enclosed body of water having a free connection with the open sea and within which the sea water is diluted with fresh water deriving from land drainage.

35
Q

What common features do all estuaries share?

A
  1. A semi enclosed coastal body of water
  2. Free connection with the open sea at least part of the year
  3. Sea water is measurably diluted with fresh water
36
Q

What are the 4 classes of estuaries based on topography?

A
  1. Drowned River Valley (Coastal Plain Esturaries)
  2. Bar-Built Estuaries
  3. Techtonic Estuaries
  4. Fjords
37
Q

Give the main features of drowned river valley esturaries.

A

Also called “coastal plain estuaries”

  • Coastal plain estuaries were formed at the end of the last ice age
  • Rising seas invaded low-lying coastal river valleys and glacial channels
  • Valleys are usually shallow with gentle sloping bottoms (v-shaped)
  • Depth increases toward the river’s mouth
38
Q

Give the main features of bar-built estuaries.

A
  • Sediment is deposited across the estuary mouth to form a partial barrier
  • Usually shallow, with reduced tidal action and extensive mud flats
  • Seasonal pulses of water may destroy bar and flush out the esuary → bar then gradually rebuilds
  • Wind is frequently the most important mixing tool for the fresh and salt water
39
Q

Give the main features of techtonic estuaries.

A
  • Tectonic motion causes large cracks or faults and folds to form in the earth’s crust
  • Estuaries formed by inundation of the land through land subsistence as a result of tectonic processes usually at a geologic fault
  • Many of the techtonic estuaries found on the west of the U.S. are seasonal estuaries; containing freshwater only a portion of the year
40
Q

Give the main features of fjords.

A
  • Drowned glacial valleys at high latitudes
  • Fjords are characterized by a deep elongated basin that is U-shaped
  • Fjords possess a ledge or barrier (sill) that separates the basin from the sea
  • The presence of the sill, together with moderately high river input, results in little tidal mixing
  • Many fjords possess an anoxic bottom layer below sill depth
41
Q

Give a brief description of the 4 types of estuaries classified by salinity levels.

A
  1. Salt-wedge estuary: river flows into relatively tideless sea
    • Strong pycnocline, little mixing
  2. Partially mixed estuary: river flows into moderate tidal range sea
    • Pycnocline present, some mixing
  3. Well mixed estuary: river flows into high tidal range sea
    • No pycnocline, well mixed
  4. Fjord: river flow and sea blocked by sill
    • Strong pycnocline, little mixing below sill depth
42
Q

What are the 3 types of estuarine organisms?

A
  1. Marine origin (Euryhaline): euryhaline (tolerate lower and varied salinity than full strength seawater >18)
  2. Freshwater origin: tolerate only very low salinities (<5)
  3. True estuarine species: tolerate a range of salinity levels (5-18)
43
Q

What are 3 common physiological adaptions for salinity regulation?

A
  1. Osmoconformers: tolerate wide fluctuations in their internal fluid
  2. Osmoregulators: maintain constant internal fluid concentration
  3. Partial osmoregulators: conform over a certain salinity range but actively osmoregulate when salinity levels are outside of this range
44
Q

What are the two strategies that plants utilize to carry out osmoregulation?

A
  1. Salt Exclusion:
    • Exclude salt from internal tissues
    • Found in salinities up to 60 ppt
    • Xylem 1/70 salinity of surrounding seawater (10x normal plants)
  2. Salt Excretion:
    • Excrete salt from glands in leaves
    • Found in salinities up to 90 ppt
    • Xylem 1/7 salinity of surrounding seawater (100x normal plants)
45
Q

Lacunae

A

Also called aerenchyma, these are pressurized interior spaces

  • Occupy majority of space in leaves and stems of wetland plants
  • Provides SAV and floating plants with buoyancy
  • Primary function is to transport O2 from leaves to roots
46
Q

Pneumatophore

A

A specialized root of certain swamp plants that branches upwards, rising above ground, and undergoes gaseous exchange with the atmosphere. Two classes:

  1. Adventitious
  2. Air roots
47
Q

Lenticles

A

Openings in branches that facilitate gas exchange

48
Q

What are 3 classes of adaptions by animals to the anoxic conditions found in wetland/estuarine environments?

A
  1. Morphological/Physiological: Gills, lungs, limbs
  2. Life History: both aquatic and terrestrial life stages
  3. Behavioral: reduce exposure to anoxic and saline stress, reduce energy expenditure to osmoregulate
49
Q

What are the two categories of fish based on estuarine/ocean habitation patterns?

A
  1. Transients: use estuary as feeding or nursery grounds
  2. Residents: use estuary for entire lifecycle (locally adapted)
50
Q

What are two adaption strategies of plants to provide stability on inundated soils?

A
  1. Drop roots: descend from branches to soil
  2. Prop roots: extend from trunk to soil
51
Q

Explain the differences in species & habitat diversity in estuarine systems.

A

High Habitat Diversity: (rocky shores, sand and mud flats, salt marshes, sand dunes, lagoons & subtidal zones)

  • Species diversity increases with habitat diversity
  • Species diversity increases within each habitat at seaward end of estuary
  • Due to loss of species intolerant to dilute conditions and the absence of estuarine specialists to replace them

Low Habitat Diversity: (sand flats, mud flats & sand dunes)

  • Species diversity decreases with loss of habitat diversity
  • Dominance of soft sediments from river input and tidal flux
  • Habitat homogeneity results in an increase in the abundance of soft bottom specialists and a decrease in total species diversity
52
Q

List the 4 types of wetland enviornments in order of their productivity values.

A

Marsh > Swamp > Bog > Fen

53
Q
A

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