Week 4- Spatial scales of distribution

What factors create spatial and temporal patterns in zooplankton

Biological and physical processes

What are the scales of zooplankton distribution

Latitudinal to regional, local and micro-scale

What are the main physiochemical properties of oceans

Surface ocean currents which are warm less dense e.g. fast flowing gulf stream with a western boundary current interacting with cold dense labrador current

SST, SSS, NO₃, O₂ gathered by satellite imageru

How do physicochemical properties of ocean affect plankton distribution

Temp- they are poikilotherms (cold blooded) so affects

Salinity- osmoconformers/osmoregulators

Light and nutrients- drive primary production

Currents- move populations

Depth- proximity to seafloor and source of adults

What are marine biogeochemcial provinces (BGCPs)

• Global classification of regions with similar physicochemical/biological charcateritsics

• Longhurst produced a subjective system (4 biomes split into 56 provinces)

What do modern marine biogeochemcial provinces (BGCPs) include

Depth, Chl a, SST, SSS

What is the latitudinal trend in number of species

High latitudes- small no. of species dominate assemblages

Low latitudes- larger no. of species dominate assemblages

What are latitudinal trends in individual size

Those in low latitudes have smaller body size to those at high latitudes

What is the latitudinal trend in overall biomass

High latitudes- high population/community biomass

Low latitudes- low overall biomass

What is the latitudinal gradient in diverity

More species at low latitudes

What explains the latitudinal gradient in diversity

Species- energy hypothesis

• SST (energy os best predictor)
  ‘More individuals’ hypothesis- more energy supports bigger communities

  ‘Evolutionary individuals’ hypothesis- as its warmer species breed quicker= more scope for genetic migration/speciation

Why are cold water taxa larger than warm water taxa both inter and intra specifically

1. Metabolic rate is higher at elevated temo as ingested ration= respiration> growth

2. Buoyancy versus relative density of seawater

3. Less phytoplankton biomass in oligotrophic warm waters

What do biomass trends reflect

Influenced by body size and productivity

What is biomass like in areas of equatorial upwelling

Relatively high phytoplankton/zooplankton density

What is biomass like in areas of temperate latitudes

Intermediate biomass with strong seasonality

What is biomass like in high latitudes

High biomass

What is no. of relative proportion of carnivorous copepods at low latitudes like

Increases

What are cold core rings like

Rotate anti-clockwise, cold, nutrient rich, productive water similar to SW-flowing labrador current

What are warm core rings

Rotate clockwise, warm, oceanic, low productivity water similar to NE- flowing gulf stream and sargasso sea

What reflects conditions of mesoscale eddies

Plankton community structure

• Productivity and biomass reflect conditions of mesoscale eddies

• Indicator species can be used to identify water masses

What are the 5 different types of patchiness (small scale) in spatial planes

1. Vectorial (regular and vertical)

2. Stochastic vertical (non regular and horizontal)

3. Social (swarming behaviour, predator avoidance)

4. Co-active(trophic interactions)

5. Reproductive and ontogenetic(life histories)

   NOT MUTUALLY EXCLUSIVE

Give an example of vectorial patchiness

Effect of oxycline

• Majority of species in O2 conditions - relatibe to oxycline

• Species are associated with different boundaries of oxycline

• Hypoxic and anoxic areas in sea are spreading which will impact communities

• Combination of competition tolerance

Give an example of stochastic patchiness

Tidal fronts

• Follow lines of constant h/u³ (h is water column depth u is amplitude of tidal currents)

• Regions of elevated surface primary production and biomass compared to mixed and stratified

Give another example of stochastic patchiness

Langmuir circulation

• Light winds create vortex type circulation is surface waters

• Parallel vortices create regions of up and down welling that concentrate particles

• Across water surface lines

Where do buoyant sinking neutral and swimming particles aggregate within or between langmuir cells

More buoyant- above langmuir cells

Sinking- below langmuir cells

Some in between cells

Give an example of social patchiness

Krill swarming

Give an example of co-active patchiness

Trophic interactions

• Lead to horizontal/vertical patchiness

• Phytoplankton distribution initially related to nutrients and water column stratification

• Zooplankton graze down phytoplankton

• Switch between inverse and coincidence patterns

• Vertical migration involved

Give an example of reproductive patchiness

Larvae near HTVs and reefs

Release of coral bundles

What are multifactor causes of patchiness

Combination

• Chl a distributed as Deep chlorophyll max

• Copepods aggregate in areas of high chlorophyll biomass

• Different species and larval stages distribute themselves at different depths to reduce competition