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Ecosystems > Lecture 3 > Flashcards

Lecture 3 Flashcards

1
Q

What does Benthic mean

A

Epifauna (on) or infauna (in) the sea bed - provide structural complexity

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2
Q

What does Demersal mean

A

Associated with the sea bed

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3
Q

What does Pelagic mean?

A

In the water column, includes plankton (passive drifters) and nekton (active swimmers)

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4
Q

What links the pelagic and benthic realms

A

Benthic organisms have planktonic larvae

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5
Q

Where is most productivity found

A

In the open ocean in the form of phytoplankton

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6
Q

What are phytoplankton

A

Single cells floating in the sea

They produce about half the oxygen in the atmosphere

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7
Q

Explain the two layered ocean

A

Light at the top, nutrients at the bottom - If the ocean was truly homogenous life would not persist

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8
Q

How to overcome the two layered ocean dilemma

A

Mixing of surface waters by wind
Coriolis effects caused by the earths rotation
Surface currents driven by ocean-atmosphere interactions
Localised upwelling of nutrient-rich deep waters driven by the above

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9
Q

How can the ocean be divided up horizontally

A 
Ocean basins
Pacific 
Atlantic 
Indian 
Arctic 
Southern
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10
Q

How can we divide up the seas

A

Horizontally by geography - ocean basins
Vertically by depth - depth zones
Biologically by productivity
Biogeographically by species composition - ecosystems, biomes, eco regions
Politically - EEZs, management units, territorial purposes, fishing areas

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11
Q

Name the major seas

A 
North
Baltic
Mediterranean
Caribbean
Red 
South China
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12
Q

Describe the continental shelf

A 
Surrounds all continents 
Up to 200m 
Shelf slopes down to abyssal plain - underwater mountains, featureless 
Ocean ridges 
Trenches down to 11,000m
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13
Q

What is the epipelagic/euphotic zone

A

Up to 200m - light enough for photosynthesis

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14
Q

What is the mesopelagic / dysphotic zone

A

Up to 1000m - enough light for animals to see - not for plants

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15
Q

What is the bathypelagic / aphotic zone

A

Up to 6000m - no light - 3/4 of marine world

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16
Q

What is the hadal zone

A

More than 6000m - deep ocean trenches

17
Q

What is longhursts bio geographical provinces

A

Oceans divided into 4 pelagic biomes based on forces regulating the distribution of phytoplankton

18
Q

What are the 4 pelagic biomes based on forces regulating the distribution of phytoplankton

A
  1. Polar biome
  2. Westerlies Biome (temperate)
  3. Trade-winds Biome (tropical)
  4. Coastal boundary Zone biome
    (Each biome occurs in every major ocean basin)
19
Q

Describe the polar biome

A

Mixed layer depth - driven by wind and currents - mixing brings nutrients up to the surface
Mixed layer constrained by surface brackish layer that forms each spring in the marginal ice zone
Allows phytoplankton to photosynthesise and powers marine food webs - mediated by polar irradiance
Low taxonomic diversity at all trophic levels

20
Q

Describe the westerlies biome

A

Mixed layer depth forces largely by local winds and local irradiance
Strong seasonality at higher latitudes
Spring production limited by nutrient availability- rely on storms to bring nutrients to the surface
Complex herbivore ecology, migratory pelagic fish driving herbivore community

21
Q

Describe the trades biome

A

Mixed layer depth forced by ocean basin scale adjustment to wind forcing - more stable
Large amplitude responses to monsoon reversal of trade winds
Pronounced diel vertical migrations of zooplankton, fish and squids
Most taxonomically diverse pelagic ecosystem

22
Q

Describe the Coastal biome

A

Diverse coastal processes (tides, river outpits) modify mixed layer depth and nutrient inputs
Production intermittent at coastal divergences and upwelling
Water shallower - benthic-pelagic coupling
-> through trophic relations and merplanktonic larvae (pelagic larvae of benthic animals)

23
Q

What are the pros of longhurst

A

Concentrates on planktonic ecosystem and the physical oceanographic processes driving it
Useful for large-scale ecological studies

24
Q

What are the cons of longhurst

A

Doesn’t cover significant marine ecosystems ecosystems (coastal regions) or taxa (fish) of particular interest to people

25
Q

Marine eco regions of the world (MEOWS)

A 
Strong bio geographic basis
Taxonomic configurations
Evolutionary history 
Patterns of dispersal and isolation
Hierarchical structure 
Combination of data-driven and expert opinion
26
Q

Realms

A

12 very large regions with internally consistent biotas at higher taxonomic levels we a result of unique shared evolutionary history
High levels of endemism, including genetic and family level
Driven by water temp, isolation and depth

27
Q

Provinces

A

62 large areas defined by distinct biotas that have some cohesion over evolutionary time
Some level of endemism , particularly among species
Driven mainly by distinct abiotic boundary features
Similar to longhurst provinces

28
Q

Ecoregions

A

232 areas of relatively homogeneous species composition - distinct adjacent systems
Species composition driven by habitat types, oceanographic or topographic features
Biogeography driven by isolation, upwelling, nutrient inputs, temp, ice currents, bathymetric or coastal complexity
Ecologically cohesive, endemism not a key determinate of ecoregion identification

29
Q

Meow pros

A

Designed to be pragmatic and relevant to management and conservation
Do their job well for coastal and shelf ecosystems

30
Q

Meow cons

A

Only consider a minority of marine taxa

Most of the worlds oceans are not covered by this scheme

31
Q

What is the aim of data driven marine biogeography

A

To integrate data across all marine species and environments to map specifies endemicity

32
Q

What data is used

A

Occurrence records if 65,000 marine species used to provide an objective, empirical, reproducible basis for biogeographic realms
Similarities and differences in species composition between grid cells used to propose a new map of marine biogeography that covers all oceans from coastal to the deep sea
30 coherent biogeographic realms determined

33
Q

Describe endemicity in biogeographic realms

A

The 30 biogeographic realms had a minimum of 17% and an average of 42% endemicity

endemicity was 4 times higher for proposed biogeographic realms compared to the “seas and oceans” indicating that the realms were the better representation of endemicity
This is above the threshold of 10% endemicity proposed for a geographic area to qualify as a biogeographic region
Species-rich benthic taxa such as Arthropoda and molluscs contributed most to endemicity

34
Q

What are the comparisons with MEOWs

A
  1. The biogeographic realms were a close match to 9 of the 11 MEOW realms
  2. This provides empirical support for marine biogeographic realms proposed based on reviews that synthesised taxon-specific and regional knowledge
  3. But this extended into deep sea and open ocean systems
  4. Results suggest that one global classification may be realistic with a close spatial relationship between the pelagic and deep sea realms
  5. This also complements that Holt et al terrestrial realms with a similar proportion of terrestrial (12 in 29% of the worlds area) to marine (28 in 71%) realms per unit area

Ecosystems (3 decks)

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