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Organisms and Environment > Lytic systems > Flashcards

Lytic systems Flashcards

1
Q

Physiochemical properties of water

A

High freezing and boiling temperature.
Polar covalent bonds within water molecule and intermolecular hydrogen bonds. Hydrogen bonds most closely associated at 4 ˚C, so liquid water denser than ice.
Ice can form barrier between air and water
Water retains heat well – releases heat in winter
Universal solvent for important inorganic molecules
Transport and reaction system; essential for cellular life

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2
Q

Physiochemical properties of water

A

High freezing and boiling temperature.
Polar covalent bonds within water molecule and intermolecular hydrogen bonds. Hydrogen bonds most closely associated at 4 ˚C, so liquid water denser than ice.
Ice can form barrier between air and water
Water retains heat well – releases heat in winter
Universal solvent for important inorganic molecules
Transport and reaction system; essential for cellular life

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3
Q

Freshwater

A

High turnover rate - divided and small
Low accumulation of salt as there is liquid outflow
Low species diversity as shorter time scale and more disrpution

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4
Q

Salt water

A

Low turnover rate
High accumulation of salt due to evaporation
High species diversity due to longer time scale and less disruption

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5
Q

Typical salt conc in fresh vs salt water

A
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6
Q

Continuity in lakes in Malawi

A

Lake Chilwra - shallow, fires out, limited biota, generalists, productive and important for fishery but alkaline at low levels so unstable
Lake Malawi - deep, doesn’t dry out, many endemic species of fish

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7
Q

UK rivers

A

Easter rivers of England more recently connected to continental Europe (due to glacial periods). Silver bream are fish found in most of continental Europe but only present in the UK in SE England
Ireland and Scotland were separated earlier - dominated by euryhaline and diadramous species. Some fish e.g. arctic charr can be either landlocked (Lake District) or move from sea to lake to spawn.

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8
Q

Freshwater composition

A

CO2 dissolves to form carbonic acid; rainwater pH about 5.6
SO2 can also dissolve further reducing the pH
Buffering capacity affected by underlying geology. Igneous rock (e.g. granite, basalt) – low buffering capacity. Sedimentary rock (e.g. limestone, sandstone) high buffering capacity.
Calcium needed for exoskeleton of molluscs/crustaceans – only present when enough Ca present (e.g. Asellus waterlouse)
Weathering supplies most of Ca, Mg, Na, K and P
Most N from fixation from air (cyanobacteria)
S from rain, snow, dry deposition
P usually limiting for plant growth
N can be limiting; abundance depends on nitrogen cycling, fixation, anthropogenic sources
Nutrient availability affects primary production
Further effects higher up the food chain through trophic cascading

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9
Q

Freshwater

A

High turnover rate - divided and small
Low accumulation of salt as there is liquid outflow
Low species diversity as shorter time scale and more disrpution

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10
Q

Salt water

A

Low turnover rate
High accumulation of salt due to evaporation
High species diversity due to longer time scale and less disruption

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11
Q

Typical salt conc in fresh vs salt water

A
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12
Q

How does agriculture affect freshwater composition?

A

Vegetation clearance, slurry from livestock, fertiliser loss

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13
Q

How do settlements affect freshwater composition?

A

Sewage – high organic matter leading to high BOD (Biochemical Oxygen Demand), increases in phosphate levels from domestic detergents (EU ban on dishwasher and laundry detergents from 2017

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14
Q

How does industry affect freshwater composition?

A

more regulations now e.g. heavy metal pollution controlled, organic pollutants e.g. hormones and hormone analogues (plastic industry, some herbicides etc.)

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15
Q

Oxygen solubility

A

Inversely related to temp

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16
Q

Eutrophication

A

Increase PP due to increased levels of nutrients

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17
Q

Oligotrophy

A

Upland, igneous rocks, upper part of catchment

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18
Q

Eutrophy

A

Lowland, sedimentary rocks, catchment increases downstream and eutophy increases with age

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19
Q

How does agriculture affect freshwater composition?

A
  1. Vegetation clearance, slurry from livestock, fertiliser loss
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20
Q

How do settlements affect freshwater composition?

A
  1. Sewage – high organic matter leading to high BOD (Biochemical Oxygen Demand), increases in phosphate levels from domestic detergents (EU ban on dishwasher and laundry detergents from 2017
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21
Q

Hypolimnion

A

Bottom layer of a water-column

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22
Q

Oxygen solubility

A

Inversely related to temp

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23
Q

Lotic

A

Flowing water
Unidirectional current
Variable size
Well mixed, isothermal circulation
Currents are eroding, leading to high amounts of suspended material
Allochthonous sources of organic matter - produced outside system

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24
Q

Lentic

A

Still water
Variable but slow current
Variable but can be deeper/wider size
Deep lakes show thermal stratification in summer - stagnation
Little suspended material, but seasonally variable. Higher if shallow and exposed body of water
AUtpchtonous sources of organic matter - produced within system

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25
Q

Why do lakes form?

A

Retreating glaciers forming basins, silt deposition or cut-off meanders in rivers, sinking valleys, extinct volcano crates, landslides, man-made reservoirs

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26
Q

Epilmnion

A

Surface layer of a water column

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27
Q

Metalimnion

A

Middle layer of a water column

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28
Q

Benthic

A

Bottom - all depths

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29
Q

Temperature/depth differences during different seasons

A

Water has high specific heat capacity so slow warming and cooling of surface
Seasonal stratification
Mixing (autumn, spring, winter if no ice)
Thermoclines in summer (stratification) – and in winter if ice (inverse stratification)

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30
Q

Oxygen

A

Cold water holds more than warm
In through atmosphere, mixing, photosynthesis
Out through inc temp, inc respire, aerobic decomposition
Stratified - oxygen near bottom is used up during aerobic decomposition of organic material - bottom may become hypoxic or anoxic
Except: good oxygen through summer in deep ologotriphic lakes and clear lakes

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31
Q

BOD

A

Biochemical oxygen demand measures oxygen depletion - incubate sample for 5 days at 20 degrees and calculate mgO2 consumed per litre

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32
Q

Pelagic

A

Open water

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33
Q

Littoral

A

High water level to euphotic depth - with light

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34
Q

Produndal

A

Zone below euphotic depth (no light_

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35
Q

Benthic

A

Bottom - all depths

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36
Q

High pelagic/littoral ratio

A

Deep, open lake, dominated by pelagic phytoplankton e.g. Windermere

37
Q

Profundal benthos

A

Homogenous, cold, little oxygen, no intrinsic food, few microhabitats, low species richness, primary consumers = bloodworm, phantom midge and pea clams

38
Q

Phytoplankton seasonality

A

Spring blooms in temperate lakes due to mixing (nutrients also mixed – more accessible); depletion of nutrients in summer due to stratification leading to drop in phytoplankton populations (although may get nitrogen fixing cyanobacteria in late summer); autumn – may get smaller peak due to mixing

39
Q

Plant communities

A

Submerged, emergent, floating vascular plants

Colonisation depth related to light extinction coefficient

40
Q

Littoral animal communities

A

Upper shore – more wave action and larger stones/gravel: algal protists and bacteria attached to rocks, caddis fly larvae (some tube dwelling), motile scrapers, mayfly and stonefly nymphs. Smaller invertebrate deeper under gravel to avoid getting crashed.
Lower shore – less wave action so finer sediment: bacteria and protozoans, invertebrates on emergent vegetation such as mayfly and stonefly nymphs, freshwater shrimps, snails, caddisfly larvae
Invertebrate predators e.g. Hydra, leeches, dragonfly nymphs
Larger predators: fish (e.g. tench) and birds (e.g. water rail) feeding on invertebrates
Piscivorous fish, birds, reptiles and mammals (e.g. pike, heron, grass snake, otter)

41
Q

Pelagic animal communities

A

Zooplankton – some independent movement e.g. diurnal (=daily) vertical migration (spend day deeper down to avoid predators, migrating up to feed during the night)
Nekton; fish e.g. charr, perch roach

42
Q

Profundal animal communities

A

Relatively simple community, e.g. Bacteria and Protozoa
If enough oxygen also invertebrates and fish
Low oxygen: bloodworms (midge larvae)
Also well oxygenated bottom waters have low diversity

43
Q

Littoral benthos

A

Heterogenous, warm, plenty of oxygen, intrinsic food, many microhabitats, high species richness, primary consumers = insect larvae and molluscs, carnivores = fish, leech, insect larvae

44
Q

Lotic systems

A

Dendritic channels with lower/higher order channels
Some areas braided or meandering
Velocity dipendendo on stizze, shape, gradient, roughness, depth, ppt
Substrate type dependent on velocity

45
Q

Sediments in estuaries

A

formed from river delta and offshore sources (during winter storms); high loads of fine suspended sediment so poor light penetration and therefore poor phytoplankton growth. Arose from either materials brought down river when they encounter higher salinities (delta formation) or transport of mud/sand into river mouth from offshore sources
L

46
Q

Lotic systems connectivity: river continuum concept

A

Longitudinal continuum upstream to downstream, e.g. higher proportion of shredders upstream (break up larger material such as leaves to smaller pieces e.g. nymphs of mayflies, stoneflies, damselflies), higher proportion of collectors midstream (filter or catch smaller particles – light levels higher here so more algal growth); more complex distribution in practice

47
Q

Lotic systems connectivity

A

Longitudinal (mountain headwater) vertical and lateral (dominance in braided reach and meandering reach)

48
Q

Estuary

A

Semi-closed coastal body of water with free connection to open sea - seawater diluted by freshwater from land drainage. Fluctuations in water temp and salinity due to tidal cycle

49
Q

Types of estuary

A

Salt wedge - gentle slope and high river flow
Vertically mixed - sleep slope and high tidal flow. Has isohalines after mixing.
Most partially mixed, some intermittent - connect with the sea only during periods of high river flow. Can be sealed off by a sand bar.

50
Q

Ionic composition of estuary

A

Sea water higher in Na+, Cl-, sulphate

River water higher in Ca2+, HCO3- and silicate

51
Q

Characteristic features of estuaries

A

interactions between tidal movements and variable rover flow high loads of fine suspended sediment, light penetration poor so phytoplankton growth is low, high levels of productivity based upon detritus carrying sediments down river or from the sea, or from decaying plant material from fringing salt-marshes.

52
Q

Detritus in estuaries

A

(dead organic matter) from river and salt-marshes leading to high levels or organic matter. Detritus feeding animals include Hydrobia snails, Corophium mud shrimps and grey mullet (fish). Deposit and filter-feeding tellin clam Angulus tenuis less common than in marine systems.

53
Q

Suspension feeding invertebrates in estuaries

A

Much less common in marine systems

54
Q

Nursery areas in estuaries

A

For commercial fish e.g. herring

55
Q

Wading birds in estuaries

A

e.g. dunlin, oyster catcher, redshank feed on invertebrates at low tide, for short periods of the year. High numbers.

56
Q

Species diversity in estuaries

A

From middle tends to be lower than for either the river or marine environment, indicating the distribution of organisms is controlled by physiochemical (abiotic) factors rather than biological.

57
Q

How does temperature affect surface dwelling and free swimming animals in estuaries?

A

More variable than in marine environment

58
Q

How does salinity affect surface dwelling and free swimming animals in estuaries?

A

Minimum salinity at low tide and maximum river flow – restricting upper limit of marine species; maximum salinity at high tide and minimum river flow – restricting lower limit of freshwater species.

59
Q

How does oxygen affect surface dwelling and free swimming animals in estuaries?

A

Saturation at a lower conc in the sea than in freshwater

60
Q

How does sediment distribution affect distribution of benthic (bottom dwelling) species?

A

Coarsest sediments in subtidal channels; particle diameter decreases with depth. In the subtidal zone this relationship is complicated by wave action.

61
Q

Intersital oxygen

A

Subtidally diffusion via interstitial water (in pores between sediment grains). Only top layers are oxygenated in this way – bacteria remove oxygen further down to give a black anoxic layer.
Intertidally oxygen is transported through water movement between grains.

62
Q

Organic matter deposition in estuaries

A

mostly deposited in areas with little water movement, e.g. mud. Finer sediment grains also have larger surface area so more bacteria adsorbed, and therefore higher N content (from bacterial proteins). Therefore, negative correlation between median grain size and 1) proportion (%) of organic matter and 2) N content.

63
Q

Productivity of benthic organisms

A

High
Density high – biomass and numerically e.g. 40 g dry weight per m2 of the polychaete Arenicola (found in worm casts) equalling 2 tonnes of wet weight per ha (higher than stocking rate for typical field of cattle).

64
Q

Standing crop

A

organisms present at a specific moment of time. Many benthic species have short lifespans so high turnover of individuals – annual productivity higher than standing crop. Explains why wading birds visit estuary mudflats.

65
Q

Marine zones

A

littoral (make up negliblie proportion of marine habitats but his productivity), neritic waters (above continental shelf), oceanic waters

66
Q

Layers of water

A

Epipelagic 6000m underworld

67
Q

Tidal power plants

A

make use of difference in potential energy between high and low tide by storing the water in dams with sluices that are closed when tide changes from high to low tide (difference in height). Water released through rotating turbines, generating electricity.

68
Q

Potential environmental impact of tidal power plants

A

reduced mixing / increased stratification leading to reduced salinity and build-up of contaminants and eutrophication. Loss of habitats (mudflats, saltmarshes). Change in benthic habitats, affecting feeding birds. Damage to migratory fish and mammals.

69
Q

% Earth covered by ocean

A

61% n hemisphere
80 south
Pacific is deepest and largest

70
Q

Sea floor

A

• average depth just over 4000 m but great variety in depth. Continental shelf, abyssal plain, seamounts, mid-ocean ridge

71
Q

Marine zones

A

littoral, neritic waters (above continental shelf), oceanic waters

72
Q

Layers of water

A

Epipelagic

73
Q

Light wavelenth and red algae

A

Blue light perpetrated deepest in clear oceans, green the deepest in coastal and red the least, so red algae found at greater depth, absorbs green and blue, but reflects red

74
Q

Waves

A

Crests and troughs – water particles move in circles. Massive forces generated by waves (1 m3 of water has a mass of 1 tonne)

75
Q

Spring tide

A

Moon and sun along same line

76
Q

Neap tide

A

Moon at right angle from the sun

77
Q

Ocean climate

A

Warm currents move towards poles and cold towards the tropics = giant thermostat

78
Q

Kelp forest

A

In temperate sublittoral
o main kelp species in British waters belong to Laminaria
o seaweed structure: holdfast, stipe and blade
o one of the most productive habitats on Earth
o refuge for invertebrates (e.g. crustaceans, snails, brittle stars), fish (e.g. rockfish), mammals (e.g. seals, sea otters)
o kelp forest has 3-D structure: substrate-understory-canopy

79
Q

Coastal upwellings

A

Important for nutrient transport, especially in tropics

80
Q

ENSO and trade-winds

A

El Nino Southern Oscillations - atmospheric and oceanic processes linked
Normally trade-winds in tropical Pacific from east to west. Removal of warm water causes upwelling in the east, near the coast of Peru
Weakened trade-winds during El Niňo years – rainfall patterns etc. change globally

81
Q

Temperature profiles at different latitudes

A

High - Well mixed, temperate regions
Mid: seasonal thermoclines, tropics
Low: permanent thermoclines

82
Q

Global primary productivity highest at

A

continental shelves, as rivers add nutrients, and in temperate and polar seas including the North Sea, the Baltic and the North Atlantic. In tropical areas only areas with upwelling have high productivity, e.g. off west coast of South America

83
Q

Antarctic food web

A

Relatively simple; short food chains possible due to high abundance of nutrients and plankton, e.g. phytoplankton → krill → baleen whale

84
Q

Kelp forest

A

In temperate sublittoral
o main kelp species in British waters belong to Laminaria
o seaweed structure: holdfast, stipe and blade
o one of the most productive habitats on Earth
o refuge for invertebrates (e.g. crustaceans, snails, brittle stars), fish (e.g. rockfish), mammals (e.g. seals, sea otters)
o kelp forest has 3-D structure: substrate-understory-canopy

85
Q

Rocky intertidal zone

A

o Upper limit determined by physical stress (temperature, desiccation)
o Splash zone (lichens, limpets), high tide zone (barnacles, limpets, spiral wrack Fucus spiralis), mid tide zone (hermit crabs, mussels, sea anemone, bladder wrack Fucus vesiculosus and saw wrack Fucus serratus), low tide zone (kelp forest, benthic invertebrates)
o Studies by Robert Paine (1966, 1974) identified cushion star Pisaster as a keystone species in the rocky intertidal of the Pacific coast of North America
o Pisaster are predators of blue mussel Mytilus
o Removal of Pisaster: Mytilus outcompeted other species by attaching themselves to the rock surface; leading to a vast decrease in the biodiversity of algae and invertebrates (28 species lost)

86
Q

Coral reefs

A

o Wide range of niches; very high biodiversity e.g. 25 % of marine fish species found here
o Different forms of corals depending on exposure, e.g. high wave action – encrusting species, moderately exposed – branched, sheltered – finely branched
o Corals are anthozoan cnidarians
o Colonial – individual polyps are connected
o Hard hermatypic (=reef-building) corals secrete calcium carbonate skeletons – mostly in warm, shallow waters
o Most hermatypic corals contain symbiotic zooxanthellae (photosynthetic, unicellular, dinoflagellate protists) which contribute to nutrition by fixing carbon. The protist can in its turn utilise nutrients captured by polyp
o Distribution limited by temperature, water clarity, salinity and nutrient level. Optimal conditions e.g. around Australian coast, Red Sea, Pacific islands.
o Coral bleaching due to increased temperatures, acidification, deposition etc. Zooxanthellae expelled as these conditions change – carbon fixation stops and polyp dies leaving only calcium carbonate skeleton

87
Q

Fringing reef

A

Close inshore

88
Q

Barrier reef

A

Separated from land by lagoon

89
Q

Atolls

A

Annular (ring forming) reefs round volcanic islands

Organisms and Environment (9 decks)

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