Lecture 3

Question 1

What does Benthic mean

Answer 1

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

Question 2

What does Demersal mean

Answer 2

Associated with the sea bed

Question 3

What does Pelagic mean?

Answer 3

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

Question 4

What links the pelagic and benthic realms

Answer 4

Benthic organisms have planktonic larvae

Question 5

Where is most productivity found

Answer 5

In the open ocean in the form of phytoplankton

Question 6

What are phytoplankton

Answer 6

Single cells floating in the sea

They produce about half the oxygen in the atmosphere

Question 7

Explain the two layered ocean

Answer 7

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

Question 8

How to overcome the two layered ocean dilemma

Answer 8

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

Question 9

How can the ocean be divided up horizontally

Answer 9

Ocean basins
Pacific 
Atlantic 
Indian 
Arctic 
Southern

Question 10

How can we divide up the seas

Answer 10

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

Question 11

Name the major seas

Answer 11

North
Baltic
Mediterranean
Caribbean
Red 
South China

Question 12

Describe the continental shelf

Answer 12

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

Question 13

What is the epipelagic/euphotic zone

Answer 13

Up to 200m - light enough for photosynthesis

Question 14

What is the mesopelagic / dysphotic zone

Answer 14

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

Question 15

What is the bathypelagic / aphotic zone

Answer 15

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

Question 16

What is the hadal zone

Answer 16

More than 6000m - deep ocean trenches

Question 17

What is longhursts bio geographical provinces

Answer 17

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

Question 18

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

Answer 18

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)

Question 19

Describe the polar biome

Answer 19

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

Question 20

Describe the westerlies biome

Answer 20

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

Question 21

Describe the trades biome

Answer 21

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

Question 22

Describe the Coastal biome

Answer 22

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)

Question 23

What are the pros of longhurst

Answer 23

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

Question 24

What are the cons of longhurst

Answer 24

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

Question 25

Marine eco regions of the world (MEOWS)

Answer 25

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

Question 26

Realms

Answer 26

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

Question 27

Provinces

Answer 27

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

Question 28

Ecoregions

Answer 28

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

Question 29

Meow pros

Answer 29

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

Question 30

Meow cons

Answer 30

Only consider a minority of marine taxa | Most of the worlds oceans are not covered by this scheme

Question 31

What is the aim of data driven marine biogeography

Answer 31

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

Question 32

What data is used

Answer 32

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

Question 33

Describe endemicity in biogeographic realms

Answer 33

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

Question 34

What are the comparisons with MEOWs

Answer 34

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