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Oceans
28 September 2015

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Tropical
Temperate
Deep sea
Arctic

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14:05

Pacific
Atlantic
Indian
Arctic

The Water Column
• Depth, temperature and photosynthesis
• Photosynthesis occurs down to 200m

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• Epipelagic (0-200m) - highest light levels, most algal activity
• Mesopelagic (200-1000m) - diffuse light, no photosynthetic wavelengths
• Bathypelagic (>1000m) - dark, cold, no sunlight, high pressure
The Sea Floor
• Continental margins - active or passive (1km out to sea)

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• Continental shelf - narrow or wide, can be modified, exposed during ice ages; 200m
Marine Biology Page 1

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Continental shelf - narrow or wide, can be modified, exposed during ice ages; 200m
Shelf break
Continental slope
Continental rise
3000-6000m deep
○ Abyssal plains
○ Abyssal hills - extinct volcanoes
○ Seamounts - active volcanoes
○ Guyot - Inactive seamounts, shrinking/subsiding

Marine Biology Page 2

Salinity
29 September 2015

13:46

Water
• H2O
• Specific heat capacity 1calorie/g/oC
Solutes
• Boiling temperature raised
• Freezing temperature lowered
• Density is affected
Salinity
• Measured from the concentration of Cl- (limited by Br, I, F in water)
○ Titrated with silver nitrate
○ Salinity as ppt: 1
...
8oC)
 Ice formed and hypersaline water sinks
 Brings oxygen and water to the depths
□ No photosynthesis below 200m
 Driven by wind and thermohaline circulation
○ Divergence
 Water rises
 Forced up by sinking water
□ Becomes surface currents driven by wind
○ Deep water currents generated

Marine Biology Page 6

Tides
02 October 2015

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13:32

Longest waves
Diurnal tides: 1 high, 1 low per day
Semidiurnal tides: 2 high, 2 low
Mixed tides: combination

Formation
• Lunar influence
○ Moon and earth rotate around common centre of gravity - 27
...
3 days)
 The lunar day is 24h50m
 Tides occur 50 minutes later each day
○ Moon's orbit up to 28
...
46 times the force exerted by the moon
○ Semidiurnal period of 24 hours
○ New moon = highest tide
 Solar and lunar matched
 Spring tide
○ First quarter (moon at 90o to Earth/Sun) = lowest tidal range
 Lowest high tide
 Highest ebb tide
 Neap tide
○ Full moon = spring tide
○ Last quarter = neap tide
• Coriolis Effect
○ "once air has been set in motion
...
This apparent deflection is called the "Coriolis effect"
and is a result of the Earth's rotation" - University of Illinois

Marine Biology Page 7

○

○ There is no deflection when seen from a stationary viewpoint
• All factors (in N
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1-9
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1-9
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1x1017J released
○ 230,000 killed
• Japan 11th March 2011
○ Underwater earthquake 9Mw
○ 1
...
Hemisphere)
• V Walfred Ekman 1902
• Hypothetical body of water
○ Infinite depth/width
○ Constant density
○ Horizontal layers
• Coriolis effect
• Decreasing speed
• Forms gyres in the ocean
○ Inward Ekman transport (Fc) balanced by outward gravitational force (Fg)
○ Elevation greater than 1m
○ Cold water pushed down - warm water pulled in
 Less primary productivity

•

Marine Biology Page 13

Result
• Global ocean circulation
• Great Ocean Conveyor Belt
○ Deep water thermohaline circulation
○ Tides and waves
○ Wind driven surface currents

Marine Biology Page 14

Exposure
06 October 2015

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14:54

Amount of waver energy a shore receives
Important in determining biological communities in the intertidal
Governed by the location of the shore and prevailing wind direction
Ballantine (1961) devised scale: 1-8

○

Sandy shore
• Wave energy sorts particles - influences morphodynamic beach state
○ Reflective
 Steep beach profile
 Coarser sediments
 Higher wave energy
○ Dissipative
 Shallow beach profile
 Finer sediments
 Lower wave energy

Marine Biology Page 15

Sediments
08 October 2015

12:00

Sediments and Biota
• Depauperate habitat - cobbles, pebbles, and granules
• Fine sediments very high secondary productivity due to high organic matter

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Sediments
• Graded on size according to the Wentworth Scale

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•

• Poorly sorted - sediments containing a range of different sized particles
○ Less packing (if fine)
• Well sorted - sediments containing similarly sized particles
• Porosity is very important

Marine Biology Page 16

○

○ Determines water content and density
○ Thixotropic
 High porosity
 High water content
 Low density
 Quicksand
 More infauna
□ Easier to burrow - liquefies under pressure
○ Dilatent
 Low porosity
 Low water content
 High density
 Less infauna
□ Dries out under pressure

Sediments in Estuaries
• Sedimentation patterns in estuaries are governed by tidal currents and river flow
• Near estuary mouth coarse, mud in the middle
• Fine material from rivers change charge and flocculates

•

Marine Biology Page 17

Gases - O2 and CO2
09 October 2015

13:18

CO2
• Atmospheric gases are dissolved in sea water
• Solubility determined by temperature, salinity, pressure, pH
• 90% of CO2 is present as HCO3-

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Dissolved Inorganic Carbon (DIC) = CO32- + HCO3- + CO2
CO2 lower in euphotic zone, higher in disphotic zone
CO2 higher in colder waters - warming releases CO2
Levels of CO2 in water acts as a buffer against pH changes
Ocean acidification
○ Seawater absorbs CO2
○ Higher atmospheric CO2 means more CO2 absorbed and a shift in seawater equilibrium
○ pH 8
...
10 since pre-industrial
 150% increase in H+
○ Impacts
 Reduced calcification
 Enhanced calcification - some algae
 Dissolution rate increased
 Decreased muscle mass
 Reduced fertilisation success
 Reduced developmental rates
 Reduced larval size
 Increased carbon and nitrogen fixation in some cyanobacteria

O2
• Surface super saturated with O2
• The depth at which the O2 consumed by respiration = O2 released by photosynthesis is the
compensation depth
• Oxygen Minimum Zone between 500 and 1000m area of high O2 abstraction
• Below OMZ O2 levels increase due to circulation
• Oxygen Minimum Zones
○ Areas low in O2
○ Caused by respiration of organisms and lack of replenishment with O2 rich water
○ Correspond with areas of low N
○ Contribute to 30-50% of the removal of biologically available N
 Nutrients - nitrogen cycle
○ Sources of CO2 and N2O
○ Permanent or seasonal OMZs
○ Vary in oxygen content, horizontal extent, thickness, and vertical depth range
○ High microbial activity - detritus
○ http://www
...
com/news/2010/100811/full/466812a
...
5 and 5oC by 2080
• Predicted that species will shift poleward
• Retraction of north and extensions of south
• MarClim project
Intertidal
• When emersed the intertidal can experience extreme fluctuations in temperature
• Temperature changes are buffered on sedimentary shores
• Estuary temperature fluctuation from the norm remain minimal

Marine Biology Page 22

•

• Higher latitude
○ Where ice forms there is little biota
○ Rock pools can freeze below -18oC
○ Constant 4oC under ice
○ Stratification can occur in rockpools on warm day
○ During the day can get significantly warmer than sea temperature
 Daniel and Boyden (1975) recorded 11o difference
Hydrothermal Vent
• Typically occur around fault lines
• Smoke can reach 350oC
• Meets 4oC water - minerals precipitate

•

Marine Biology Page 23

Light
13 October 2015

14:19

• Angle of incidence
○ The greater the angle the more reflection
• Upon entering water light is scattered and absorbed
• Bacteria, plankton, and sediment scatter light
• Spectral quality and quantity changed with depth
• Water readily absorbs red wavelengths
○ Only 1% remains at 10m depth
• Blue wavelengths penetrate deepest
• Mesopelagic
○ 200-1000m
○ Light is present
○ Not enough for photosynthesis
• Bathypelagic
○ >1km
○ There is no light
• Other factors
○ Diel variations (day/night)
○ Seasons
○ Latitude
○ Particle density and size
○ Upwelling, tides, current, land run-off
• Light is essential for photosynthesis
• Tropical coral reefs, sea grasses, and algae are dependent on water clarity
• Cannot tolerate smothering by sediments

Marine Biology Page 24

Nutrients
13 October 2015

14:25

Required Nutrients
• 1o productivity

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Nutrient sources
• Carbon:nitrogen:phosphorous - Redfield ratio

• If N:P>16 phosphorous is a limitation
• If N:P<16 nitrogen is a limitation
• C:N ratio is typically 6
...
3-0
...

○ Attaching to moist/shaded areas
○ Reservoir - take up water into enlarged mantle cavity
○ Tolerance for high osmolarity
 200% blood conc
 Reduced urine production
 Nitrogenous waste stored as uric acid
○ Increased membrane leakage

Low Temperature
• Less problematic
• Sub-zero exposure
• Freezing and algae
○ Some of desiccation outcomes
○ Solutes deprived of water - increased osmotic stress
○ Compromised membrane permeability
○ Different tolerance at different beach heights
 Freezing intolerant species release lots of amino acids on reimmersion - can be
measured
• Metabolic adaptation to cold
○ Talorchestia megalopthalma burrows and essentially shuts down
○ Emerita talpoida increases metabolic rate
 Consumes more O2, lethal temperature decreased from 37o to 27oC in winter
• Antifreeze
Many intertidal species can "supercool" - stay unfrozen below freezing point
Marine Biology Page 31

○ Many intertidal species can "supercool" - stay unfrozen below freezing point
○ Antarctic - sea temperature ~1
...
-15oC
○ Taxa including nemertean, echinoids, copepods, gastropod molluscs, all demonstrate
ability to supercool
 -5
...
1oC
• Frozen fish
○ Teleost (bony) fish are hypoosmotic to seawater
 Less salt than SW
○ Tissue fluids freeze at -0
...
9oC
 Seawater at poles can be -2oC
○ Production of glycoproteins and lipoproteins that lower freezing point of tissues or
prevent ice crystals from forming
○ Glycoproteins prevent formation of ice lattice
 Other solutes are frozen out of the lattice, increasing osmolarity outside water-ice
• Homeotherms in the cold
○ Regulated body temp allowing reactions to occur at steady temperature
○ Usually lose heat to the environment and must reduce this to conserve energy
○ Ocean temperatures less than 27oC and sometimes sub-zero
○ Insulation
○ High Mr
○ Thermal insulation
 Water conducts heat 25x better than air
 Coarse dense fur
 Sub-cutaneous fat/blubber - 11cm thick in polar bears, 1/3 of seal weight
○ Emperor Penguins
 Low SA : Vol
 Large body mass
 Stiff feathers to reduce wind effect on convective heat loss
 Huddling
 Tcrit=-10oC
○ Counter-current heat exchange
 Appendages less insulated
 Arteries surrounded by veins
□ Most heat returned to core
□ Arterial blood cooled
□ Venous blood warmed
 Large pelagic fish use Rete Mirabile to keep metabolic muscles warm

Considerations for Sandy Shores
• Burrowing to avoid problems
• Sediment characteristics
• Movements with the tides
• Thermal buffering/season shifts in depth
• Thermal tolerance/strategies
○ Meiofauna/infauna
○ Reduced biomass in water
○ Depth migration
○ Temperature buffering of sediments

Marine Biology Page 32

Gas Exchange and Respiration
23 October 2015

13:23

• Most eukaryotes require O2
• ATP synthesis
• Increased activity increases oxygen demand
Diffusion
• Sea water has dissolved O2 from atmosphere and photosynthesis
• Animals and plants need
○ Thin respiratory surface
○ Close water contact
○ Circulation
○ Maintained diffusion gradient
• Simple diffusion
○ Cnideria
 Anthazoa - anemones
 Simple diploblastic - no circulatory system
 Ciliated surfaces creates water flow
○ Porifera
 Porocytes - water channel cells
 Osculum - exhaling mouth
 Choanocyte - Flagella drives current through
○ planaria
• Annelids
○ Gills - arose multiple times, very diverse
○ Always external gills - though some worms tubiferous (housed in tube)
○ Some store O2 during resting periods at low tide
Blood Pigments
• O2 carriage
• Haemocyanin
○ Cu
○ Blue
○ Molluscs and arthropods
• Haemerythrin
○ Fe
○ Red
○ Sipunculids, polychaetes, branchiopods
• Chlorocruorin
○ Fe
○ Red
○ Some polychaetes
• Haemoglobin
○ Fe
○ Red
○ Echinoderms, polychaetes, arthropods, vertebrates, nematodes
• Different affinities for different environments
Molluscs
• Gill structure - ctenidium
• One-directional water flow
• Bivalves
○ Rolling and fusion of mantle into siphons
 Inhalant and exhalent
Marine Biology Page 33

 Inhalant and exhalent
○ Feeding and respiratory gill
• Nudibranch
○ No shell
○ Secondary gills - not normal mollusc gills
 Rhinophores
• Cephalopods
○ 2-4 heavily folded gills
○ Lack cilia
○ Cutaneous gas exchange
Echinoderms
• Coelomate - ciliate lining
• Papulae and tube feet
• Tube feet may be modified into tentacles
• Feet and internal cavity gas ciliated gas exchange surfaces
Arthropods
• Haemocyanin
• Gills associated with appendages
• Appendages contribute to flow
• Barnacles
○ Respiratory surface includes limbs (cirripeds) and mantle epithelium
Fish
• Countercurrent gills (opposing water and blood)
• Highly developed
Aerial Exposure
• High shore emersion = O2 depletion
• Inverts that undergo anaerobic respiration produce succinic acid, alanine, and lactic acid
• Acids neutralised in some bivalves by shell dissolution
• Some organism respire aerial O2
○ e
...
clam gaping - M
...

○ Copious amounts ingested and copious faeces produced
○ Microbial decay and fragmentation facilitate
Suspension/Deposit Feeding
• Trap or sieve suspended particles from water column
○ Passive - natural currents
○ Active - generate water flow
• Most suspension feeders rely on phytoplankton as food source
• Reynolds number
○ Inertia/viscosity
○ Low Re, lack of inertia, passive sieving inefficient
• Sand dollar
○ Tube feet
○ Pass particulate material along furrows to mouth
• Sea potato Echinocardium chordatum
○ 20cm burrow - respiratory furrow
Sticky tube feet around mouth select food
Marine Biology Page 36

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○ Sticky tube feet around mouth select food
○ Burrowing and feeding with specialised tube feet
Bivalves
○ Scrabicularia plana
○ Bury in sediment
○ Inhalent/exhalent siphons - cilia generate current
 Use inhalent like a hoover - active
 Hold inhalent up and let current carry sediment in - passive (mostly)
○ Sort sediment by size and weight using palps
Lophophorates and porifera
○ Choanocytes create water currents and trap particulates
○ Flagellum - current
○ Microvilli - trapping
Filter feeding - fan worms
○ Radioles lined with paired pinules, lined with cilia
○ Cilia generate current and trap particles
○ Particles transported to central groove along radiole
○ Particles sorted at base of radiole - some used in tube building
Nereid
○ Omnivorous
○ Scavenger/predator
○ Deposit feeders
○ Filter feeders
 Spin funnel shapes mucus net
Chaelopterus
○ Polychaete worm
○ Burrow tube
○ Parapoda used to pump water through
○ Mucus bag spun between front limbs
Setose filtration
○ Crustaceans
○ Mole crabs
 Uses wave backwash - passive filtering
○ Barnacles
 Cirriped feeding
 Grasp through water - active
 Switch orientation of cirripeds in high flow - passive

Grazing
• Gastropod grazing
○ Radula
○ Subradular membrane moving over buccal mass erects teeth
○ When retracted, material is drawn in
○ Modified for predation - cone shell
• Echinoidea (sea urchin)
○ 5 calcareous plates, arranged radially and ending in teeth
○ Muscles operate jaws to extend and bite or scrape
○ Teeth replenish rapidly (1
...
4hr cycle
• Eurydice
• Very specific 12
...
- crab species
○ Crab egg hatch and begin development in full seawater
○ Megalopa stage migrate into estuary to continue metamorphosis
○ Use currents and tides to maintain position
• Drop to deeper water on outward tide (less pronounced effect)
• Move to surface on incoming tide (pushed into estuary)
• Tidal body clock governs vertical migration

Marine Biology Page 40

Buoyancy and Locomotion
06 November 2015

13:43

• Necessary for position maintenance
Water
• 800x more dense than air
• 60x more viscous
• Liquid incompressible
• 3D environment
• Sinking rate = organism density (W1) - water density (W2)/surface of resistance (R) x viscosity
(V)
○ If W1>W2 organism will sink
• Sinking components = proteins and structure
• Floating components = lipids, some fluids, and gas cavities
Planktonic Organisms
• By definition cannot move against water flow
• Must remain in photic zone
• Increase surface of resistance
○ Ornate structures - increased drag
○ Volume still low
Reduction in weight
• Alter composition of body fluid
○ Reduce density to below seawater's (1
...
g
...
01
• Cephalopods
○ Coelomic cavity takes up 60% of body cavity
○ Ammonium content (protein metabolism) and body mass in Histioteuthis heteropsis
changes with ae, linked with depth migration
Fats
• Lipids have a specific gravity of approximately 0
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57-0
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g
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g
...
g
...
g
...
g
...
g
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g
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g
...
g
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g
...
g
...
Most larvae negative geotropism
 Chemical factor very important - conspecifics, heterospecifics and biofilm
...

 Mates (sessile)
 Associational defence
 Correct conditions
 Increased longevity
○ Cons
...
(2006)
○ Settlement Inducing Protein Complex (SIPC)
○ Glycoprotein synthesised and released in cuticular parts
 Limbs
 Gut
 Carapace
 Penis
 Antennule
○ Cyprid attachment disk also positive for SIPC
Mytilus drifting and byssus threads
• Planktonic larvae must eventually settle
• If inspection fails substrate is found unsuitable larvae must migrate
• Mussels secrete long mucopolysaccharide thread
• Thread generates increased viscous drag
○ Animal resuspended in water column
• Once suitable substrate found (filamentous substrates)
○ settle

Marine Biology Page 47

Mesopelagic, Bathypelagic, and Biodiversity
12 November 2015

11:52

Pelagic habitats
• Oceanic division

Mesopelagic
• 200-1000m
• Shorter wavelengths (blue)
• No 1o productivity
• O2 variable - can be anoxic OMZs
• Reduced temperature with depth (down to 5oC)
• Reduction in zooplankton
• Increase in pressure (20-100atm)
• Lots of dissolved and particulate organic matter (DOM, POM)
Bathypelagic
• >1km
• Only light is bioluminescence
• No 1o productivity
• O2 abundant
• Constant temperature, 1-5o
• Gradual increase in salinity
• Gradual pressure increase (>100atm)
• Many meso- and bathypelagic species have 3 strategies to manage energy
• Consuming available food (no limitations)
• Efficient digestion, absorption, metabolic conversion
• Limit energy expenditure
Carbon Consumption
• Shift from filter feeding to carnivory with depth
• Tendency to adopt 'lurk and lure' strategy
• In fish, evolution of,
○ Lures
○ Increased size/length of sensory appendages
○ Ability to consume large prey
○ Generalised consumption
○ Distendable stomachs
• In invertebrates
○ Ability to consume large amounts when available
○ Generalist scavengers
○ 1 meal can last a year
○ Elastic - can distend
Saving Energy
• Metabolism
○ Many pelagic species show reduced metabolism with depth
 Adaptation to lower food availability
 Enzymatic adaptations to greater pressures
 OMZs
 Diminished light levels reducing selective pressure for fast swimming
organisms
• Buoyancy
Marine Biology Page 48

• Buoyancy
○ Reduction in density favoured
○ Mechanisms
 Increase water content
 Increased light ion concentration
 High lipid concentration
 Loss of swim bladder
 Reduced skeletal density
Effects of Pressure
• Deep sea species have enzymes tolerant to high pressure
• However, lower catalytic efficiency
• Homoviscous adaptation of cell membranes - changes in fluidity
○ Altered types of lipids - unsaturated
• High pressure makes inflation of soft walled bladders difficult

Sight
• Many mesopelagic fish have upwardly pointing eyes
○ Tubular
○ Silhouetted prey
• Eyes have large aperture lenses, focus on small part of retina
• Typically no cones, lots of rods (often stacked in multiple retinae)
• Tapetum - reflects light back into retina
• Pigments sensitive to short wavelengths
• High neural convergence
○ Many rods to one nerve
○ More likely to initiate action potential
• Many species have aphakic gap to allow maximum light into eye
• Anstomias, pachystomas, malacosteus, are sensitive to red wavelengths
• Some genera have yellow lenses to distinguish natural light and bioluminescence
• Very deep living organisms show reduced eye complexity and size
○ Photosensitive pits
• Histioteuthis has 1 tubular and 1 normal eye
• Crustaceans with compound eyes have are blinded when exposed to sunlight very sensitive
• Gammarids from surface to bathypelagic we see:
○ Increase in size
○ Asymmetry
○ Increased size of ommatidia (hexagonal components of compound eyes)
○ At greater depths reduction in all of the above

Chemoreception
• Very important for locating food falls
• Amphipods - Orchomene and paralicella can appear within 30-40 minutes
(otherwise torpid)
• Sensitive to 10-12M
• Pheromones important in conveying messages to conspecifics
• Low biomass/abundance of organism means few encounters
• Olfactory lamellae enlarged and regressed
• Sexually dimorphic (bathypelagic), no sexual dimorphism (mesopelagic)
• Those that have microsmatic organs use other methods to hunt prey e
...
vision in
Malacosteus
• Likelihood of encounter related exponentially to perception distance
• Arguropelecus hemegymnus females detected in 1 hour vs
...

• Silvering
○ Guanine panels parallel to surface in stacks
• Iridophores - reflective cells in squid etc
...

• Symbiosis
○ Anglerfish, argentinoid fishes, deep-sea cods etc
...

○ Camouflage
 Match light filtering from surface
○ Indication of unpredictability

Marine Biology Page 50

Marine Ecology
16 November 2015

13:58

Ecology
• Ernest Haeckel 1896
○ "The studying of the interactions between organisms and their environment"
• Charles Krebs 1972
○ "Ecology is the scientific study of the interactions that determine the distribution and abundance of
organisms"
Gradient
subtidal intertidal vertical horizontal Critical limit too little Critical limit too much
Biogeographic Patterns in Community Structure
Thermal
Y
Y
Y
Y
Y
Y
• Biogeographic patterns as a result of organismal affinities to
Light
Y
Y
Y
Y
Y
Y
○ Temperature
○ Wave action
Desiccation
Y
Y
Y
○ Light and nutrients
Salinity
Y
Y
Y
Y
Y
○ Habitat availability
Wave action
Y
Y
Y
Y
Y
○ Dispersal dynamics

•

•
•

•

○ Biotic interactions
 Competition
 Predation
 Facilitation
Gradients
○ Temperature
○ Light
○ Desiccation
○ Salinity
○ Wave action
○ Particle size
○ Pressure
○ pH
Deep water relatively stable
Shallow/intertidal
○ Temperature
 Immersion/emersion
 Latitude
 Time tide - low tide at midday in Plymouth, midnight in Bangor
○ Disturbance
 Wave action
 Substratum particle size
○ Salinity
 Rainfall/evaporation from rockpools
 Evaporation in tropics
Gradient land --> sea
○ Intertidal: desiccation, temperature
○ Subtidal: light, pressure

1
...
Light
• Photosynthesis not possible without light
• Light intensity much lower in water than in air
• Turbidity reduces light penetration
○ Runoff from terrestrial sources
○ High productivity e
...
blooms
○ Dredging
• Primary producers often limited to within 50m
North sea <10m

Marine Biology Page 51

Particle size

Y

Pressure

Y

Y

Y
Y

Y
Y

○ North sea <10m
○ Clear tropical waters >100m
3
...
Particle Size Gradient
• Boulder
○ Epifauna and fauna
• Cobbles
○ Very little life
○ Lots of disturbance
○ Crushing
• Sand
○ Infauna
• Mud
○ Infauna
○ Macrophytes
○ Low disturbance

Morphodynamic State
• Slope
• Sediments
• Wave exposure
• Dissipative
○ Fine sediment
○ Shallow
○ High tidal range
○ Benign swash
○ Rich fauna
• Reflective
○ Coarse
○ Small waves
○ Steep slope
○ Small tidal range
○ Harsh swash
○ Impoverished fauna
5
...
restrict due to post-settlement
mortality

Marine Biology Page 57

Structuring Capacity of Herbivory
19 November 2015

12:32

• Consumers can strongly influence community structure and ecosystem processes
○ Understanding consumer impacts and their variability has been a primary goal of community ecologists
• True predation
○ Pre
○ Kill several or many in lifetime
○ Generally consume prey in its entirety
• Herbivory
○ Consume parts rather than whole
○ Harmful to fitness but rarely immediately fatal
○ Attack large numbers of prey
○ E
...
grazers
• Detritivores
○ Consume dead material
Herbivory in Aquatic Systems
• Rates of herbivory 2-3x greater in aquatic vs terrestrial environments
○ Globally reduce 10 producer abundance by 68%
○ Greatest role on rocky reefs
• Grazing impacts on producers dependent on producer traits
• Macrograzers (>2
...
5cm)
• Molluscs strong role on rocky reef
○ Greater than sum of multiple species
• Multiple species and fish strong role on coral reefs

•

Case Study 1: Rate of Herbivory in Structuring Intertidal Rocky Shore

Exposed
• Physical factors
• Waves remove algae
• Few propagules settle
• Dominated by filter feeders and grazer

Moderately Exposed
• Dynamic balance between grazers and
microalgae
• e
...
limpets, winkles, chitons, crabs

Algal Biofilms
• Any immerse hard substratum
• Diatoms, cyanobacteria
• Provide food for a range of grazers
• Limpets primarily consume biofilm
○ Consume macroalgae if food limited

Limpets
• Feed using radula
• Stronger than rock
• Leave grazing marks
Torry Canyon 1967
• World's first major oil spill off Cornish coat
• 75000 tonnes of chemical dispersant used to disperse oil on the coastline
• Mass mortality of birds, fish, invertebrates due to dispersant
• Alan Southward monitored recovery 1967-77
• Pioneer algae
• Fucus 90-100% cover
• Limpets slow increase, decrease Fucus ~1971
• Long term observational study
○ Nothing on causation

Marine Biology Page 58

Sheltered
• Biological factors
• Sweeping action of macroalgae inhibits settlement
• Nearly monospecific stands

•

Mosaic of Algal Patches
• Exclude areas and remove limpets
• Fucus grows
• Harder for limpets to graze across barnacles
○ Patches of Fucus
○ Can grow to size that limpets can't graze
• Limpets aggregate in shade and shelter of Fucus patches
○ If Fucus lost limpets spread out, barnacles settle, Fucus grows etc
...
depressa (Britain at far North extent of range)
• Wax discs in blocked off areas
• Grazing patterns
○ %area of wax stripped
• Vulgata generally consuming more than depressa
○ Generally more Fucus in depressa area
• Different reproductive cycles
○ Different species show different patterns

•

Case Study 2: Herbivory on Coral Reefs
• Fish and herbivores
• Can negatively affect coral recruitment through consumption of propagules and algae
• Positive affect through control of algal recruitment and growth
○ Algae can outcompete and overgrow coral
• Early observations
○ Healthy reef systems fishes control abundance of algae
○ Over fishing
○ Cyclones and disease killing urchins
○ Phase shift
 Switch from 1 dominant state to another
 Coral dominated to algal dominated
• Experimental studies

Marine Biology Page 59

• Experimental studies
○ Excluded medium and large fish herbivores using case for 30 months
○ Lack of herbivory led to
 Increased macroalgal cover
 Altered macroalgal community
 Sargassum spp
...

○ Is macroalgal phase shift becoming the norm?
○ Bruno et al
...
For slow growing non acropoid (plate and massive)
 Further growth following disturbance = greater habitat for fish to graze down algae
○ Lower fish diversity and less functional redundancy when populations fluctuate
○ Macroalgae bloom faster in Caribbean
 Higher recruitment
 Reduced nutrient limitation

Marine Biology Page 60

Structuring Capacity of Predator-Prey Relations
20 November 2015

13:32

Food Chains

Energy lost at each trophic level

Food Webs

• Food web metrics
○ N links (L)
○ Linkage density (L/S)
○ Connectance (L/S2)
○ Generality (n resource/taxa)
○ Web complexity
○ Interaction strength
Trophic Control of Food Chains

Marine Biology Page 61

Case Study 1: Top Down Control
• Rocky shore Pacific NW - USA
• Mytilus - Mussels
○ Creates monospecific stands
○ Upper limit set by desiccation tolerance
○ Lower limit by predation
• Pisaster ochracens
○ Vertical distribution limited by physical factors
○ Mytilus is important prey item
○ Where Mytilus is absent increased diversity of algae and insects

•

○ Removed Pisaster in 62, returned them in 68
• Keystone predator hypothesis
○ Species whose impact is disproportionately large relative to its abundance
○ Large shift in structure of community

Marine Biology Page 62

Case Study 2: Bottom Up Control of Antarctic Food Web

• Ecologically important Euphausids
○ Krill
○ 86 species worldwide
○ Fish, birds, marine mammals
○ Commercial fisheries
 Feedstock for livestock/farmed fish
 Peak of 446,000 tonnes 1968
○ Omnivorous species
 Sea ice algae, detritus, zooplankton
○ Euphasia superba Antarctic Krill
 Important food web component
○ 75% higher order predators' diet is zooplankton
 Euphasids 70%
 Blue whales may eat 8 tonnes a day
○ Most information comes from land based predators
 Penguins, seals
 Can capture more easily
 Scat
Known to be imporntant component pelagic species - less information
○
○ Competition for krill strong affect on abundance of predators
○ Whale reduction hypothesis
 Commercial whaling= more krill for competitors
 Evidence for environmental change effects

Annual krill consumption (tonnes x 106)



Predator
Baleen whales
Seals
Penguins
Fish
Squid

1900
190
50
50
100
80

○ Low krill abundance= more trophic links to higher order predators

Marine Biology Page 63

1984
40
130
130
70
100



 Less energy reaching top
 Baleen whale distribution affected
 Climate change implications
○ Krill abundance related to winter ice extent
 Winter ice algae
 Plentiful food, lower larval mortality
 Climate change
Case Study 3: Diel Vertical Migration
• Daily migration between surface and deeper waters
• Most characteristic planktonic behavioural feature
• Biggest animal migrations by biomass
• At least some species of all major zooplankton groups
○ Marine and freshwater
• Epi and mesopelagic species exhibit behaviour
• Deeper in day
• Shallower at night
• Nocturnal migration
○ Up and sunset
○ Down at dawn
○ Common marine zooplankton
• Twilight migration
○ Up at sunset
○ Down at midnight
○ Up near dawn
○ Down by daytime
• Reverse migration
○ Down at sunset
○ Up and sunrise
○ Least common
• Distance varies
○ Copepods several hundred metres 10-170m/h
○ Euphausids and pelagic shrimps 800m+ 100-200m/h
• Depth range may be inhibited by thermocline, not always
• Proximate cause = event immediately responsible to observed response
• Ultimate cause = 'real' reason
• Proximate Cause
○ Light intensity
○ Sunny v cloudy
○ Moonlight v clouds
○ Seasonal
○ Eclipses
• Ultimate Cause
○ Clear costs
 Separation from food sources
Marine Biology Page 64

 Separation from food sources
 Colder at depths
○ 3 categories
1
...
Predator evasion hypothesis - Kremer and Kremer 1988, avoiding visually orienting predators
3
...
Unlikely to be cause
...
)
• Can influence population dynamic, species distributions, and evolution
• Competition is common - once considered biggest driver of community organisation
○ Predation, facilitation, recruitment, disturbance
• Types
○ Exploitative
 Indirect
 By depletion of shared resource
○ Interference
 Direct interaction
○ Scramble
 Resource utilisation
○ Contest
 Behavioural interaction
• Consumptive competition: Grazers and Food
○ Cellana tramoserica
 Graze on biofilm and very small algal germlings
○ Siphonaria denticulata
 Graze on microalgae, leaving basal parts of algal thalli
○ Is there competition?
 Enclosed in single and multispecies enclosures at different densities for 12 weeks
 Siphonaria only low mortality with conspecifics
□ High mortality with Cellana
□ Cellana consumes microalgae and germlings of Siphonara diet
 No negative effect of Siphonara on Cellana
□ Don't consume microalgae, leave basal area
• Pre-emptive Competition
○ Many species outcompete by arriving first and preventing settlement
○ e
...
Potelsia palamaeformis and Mytilus sp
...
g
...
Interspecific Competition
• Enclosures of species in isolation, together, and at different densities
• Higher densities increased mortality and reduced biomass across intraspecific treatments
• Both species same effect at all densities
• Intraspecific greater effect than interspecific for Patella vulgata
• Intra often thought stronger than interspecific
○ Exactly the same resources
Competition and Other Processes
• Nucella not on high shore (whelk)
• Preferentially consumes Semibalanus
○ Decreased competitive effect with predators present
○ Semibalanus doesn't reach carrying capacity, competition low effect
Facilitation
• At least one species benefits, no harm
• Intraspecific competition switch to facilitation
○ Maine cooler than Rhode Island
 Coasts cooler than bays
○ In cooler location solitary individuals did better than with neighbours
 Competition for space
○ In warm locations low levels of solitary barnacles
 Crowding reduced barnacles body temperature
 Facilitated survival
• Interspecific competition to facilitation
○ Manipulated cover at high and low shore
○ Relative role of positive and negative effects
○ High shore cleared spots higher stressors
 Increased temperature
 Increased desiccation (% water loss from sponges)
○ Recruitment to three treatments
 Lower on HS than on LS
 Shore height x canopy cover interaction
□ Canopy cover positive effect on high shore
□ Negative or neutral on low shore
 Survival and growth similar patterns
○ High predation at low shore
 More likely beneath canopy - negative effect
○ Grazers reduced macroalgal abundance below canopy - negative effect
○ Positive effects of one species on other becomes more important under harsher
conditions
Model Drivers of Community Structure
• Predation more important at low environmental stress
○ Mobile predators restricted to benign environments
Marine Biology Page 67

○
• Competition more important at intermediate stress
○ Populations reach carrying capacity
• At high environmental stress populations don't reach carrying capacity
• Associated defence
○ e
...
crowding with unpalatable species

Marine Biology Page 68

Larval Dispersal and Supply-Side Ecology
30 November 2015

13:13

Larval Dispersal
• Nearly all marine organisms have a period of broad dispersal
○ Planktonic
• Can last ours to months
○ Longer = more dispersion
Supply-Side Ecology
• Variation in number of offspring produced, settling, and timing of settlement
○ Vary in time and space
• Supply of propagules and recruitment to adult populations are considered as important as processes such as
predation, competition, facilitation, and disturbance
• Most of our knowledge comes from barnacles and mussels, with some tropical fish research
○ Less on algae and other invertebrates
Survival in Plankton
• Zooplankton important trophic link
○ Larval stages subject to high mortality - enormous variation in number of surviving propagules
• Environmental factors can influence larval duration
○ e
...
increase in temperature shortens larval duration, reduced exposure to predators
• e
...
breeding population of 1000 females produces 1 million eggs during a breeding season
○ Nt (surviving at end of day) = N0 (start no
...
76
0
...
62

1,148
3,981
13,804

251
1,000
3,981

55
251
1,148

○ 10% change in mortality and period of development leads to large changes in N t
Settlement and Recruitment
• Some habitats no individuals will settle, others large numbers settle
• Unlikely to find widely repeated assemblages
• Difficult to predict future trends (fishery management)
Variation in Recruitment and Intensity of Species Interactions: Local Scale
• Recruitment largely determines adult distribution, abundance patterns, and influences strength of biotic
interactions
• Locations with low larval settlement rates generally low adult densities
○ Varies within years slightly, more between years - based on settlement
○ Mortality not density dependent, no competition, low predation (potential allee effects due to distance
reducing mating capability)
• Locations with high settlement have high adult density
○ Vary greatly within years, slightly between years - at carrying capacity
○ Mortality density dependent, due to biotic variations
 E
...
Pisaster
Variation in Recruitment and Intensity of Species Interactions: Broad Scale
• Upwelling important oceanographic process along many coastlines
○ Western North and South America
○ Western Africa
○ Southern New Zealand
• Where upwelling is strong larvae are pushed offshore and recruitment is low

○

• Where upwelling is intermittent larvae are pushed onshore and recruitment is high
• Variation in upwelling influences larval supply and therefore species interactions

Marine Biology Page 69

• Variation in upwelling influences larval supply and therefore species interactions

•

• Patterns similar for mussels and barnacles
• Recruitment and adult abundance strongly correlated north of 32 oS where recruitment is low = population
recruitment limited (fewer relaxations in upwelling)
• South of 32oS correlation non-significant/weak = post recruitment processes influence adult abundance
(predation)
• Regional-scale discontinuities in upwelling regime affect normal regional patterns of recruitment variation
• Meso-scale variation in upwelling variation only has a weak affect
• Further experiments into impact of post-settlement processes (red square shows impact of high predation)
○ With and without predators

○

○ Southern sites predators important
 60-80% mussel cover without predators, algae outcompeted
○ Northern sites
 Neither mussels nor barnacles increased with removal of predators
 Predation not creating patterns

Mode of Dispersal and Predator Prey Dynamic
• Widely dispersing unlikely to settle near parent
○ Important implication for evolutionary adaptation, modifications of life history, behaviour, and morphology
○ Unlikely for ability to e
...
outcompete competitor to evolve if only some individuals are competed by it
• For direct developers likely to be selection for traits with positive impacts on performance
• Wieters et al
...
g
...

• 2-3 years Gigartina dominated, 60-90% cover
• Mechanisms of this pattern
○ By clearing Ulva - mid-successional species increased
○ Clearing mid-successional species - Gigartina increased
○ Each coloniser inhibits later successional species
• Interaction between physical and biological
○ Ulva more susceptible to desiccation than Gigartina
○ Ulva more susceptible to grazing by Pachygrapsus crabs
○ Ulva more susceptible to loading with epiphytes
Disturbance, Succession, and Diversity
• Larger boulder disturbed less regularly than medium and small
• Mean density of mid-successional species higher on medium than large
• Inferred that at intermediate disturbance leads to increased abundance
...
g
...
e
...
g
...
g
...
g
...
g
...
3cm disturbance
○ Brissopsis lyrifera
 Subsurface burrowing deposit feeder
 2-3cm depth
 Bigger
 Burrowing movement
○ Abra alba
 Surface deposit/suspension feeder
 Little movement
 Bigger than Nuculoma
○ All species heterogeneous in space and time
○ May be important in establishing environmental diversity
○ Experiment
 Box cores at 3 densities for shells, 1 density for Brissopsis

Marine Biology Page 74

□

 2 replicates of each, 2 controls
 Left 20 weeks
 Alpha diversity - richness within area
 Beta diversity - change in diversity between sites
 Community structure



 Density of bioturbators changed richness, turnover, and structure

Marine Biology Page 75

Detecting Anthropogenic Impacts in Marine Ecosystems
03 December 2015

11:16

Changes in Anthropogenic Impacts
• Change in 12 anthropogenic stressors 2008-2013 Halpern et al
...
(2004)
○ Followed recovery of oyster dredging in New Zealand
 Recover dependent on time since fishing ceased and presence of source populations

○

Measuring the Effects of Human Activities
• Variety of metrics/measures
• Univariate
○ Single value calculated
○ e
...
change in richness, abundance
• Distributional changes
○ Measure distribution of individuals or biomass among an assemblage of organisms
○ Aggregate response
• Indicator species
○ Species that suggest good or poor quality
• Multivariate
○ Multiple species measured in response
○ Community level information
Detecting Ecological Event
• Difficult
• Must be asking the right question
○
• Measure correct response
• Experimental design that detects change
○ Replicates and controls
○ Must eliminate all other variables as the cause

Detecting Change:
• Fully Replicated Design
○ Peeler crabs (pre-ecdysis Carcinus maenas) form a commercial level recreational fishery bait
○ Objects placed in soft sediment habitats to encourage crabs to settle - harvested
 Crab Tiling
Can occupy kilometres of mud-flats
Marine Biology Page 77

○
○
○
○
○

Can occupy kilometres of mud-flats
Mudflats and associated diversity provide food for wintering birds and commercially important species
What are the impacts of crab tiling on benthic diversity? Sheehan et al
...
2013
• 3 MPA, 3 control, 3 impact

○

• Sampled 2004-2010, MPA from 2007
• 25 lobster pots at each control and impact site

Marine Biology Page 78

• Variable abundances between regions
• All sites, significant increase
○ 2 sites MPA abundance > control
○ 1 site shows MPA not working - detected by BACI
• MPA designation a success in this situation
Making Space for Natura in Coastal Engineering
• Up to 80% of Welsh coastline is hardened
• >80% in Singapore
• These usually act as poor analogues for natural hard substrates
○ Lack heterogeneity
○ Lack water retaining features
○ Lack rare and mobile species
• Ecological engineering long history in terrestrial systems
○ Lags behind in marine systems
• 2010 - addition of breakwater at Twynn
• Homogenous granite blocks
• Cannot be replicated
○ Too expensive to construct additional barriers to test 1
○ Asymmetrical
• 1 impact site, 3 controls - burnt back to bare rock to match
• Richness similar on artificial vs natural
• Different community composition
○ Similar richness, different species
○ Just richness not an adequate measure of impact
○ Did support rare and mobile species
• Policy: incorporate water retaining features

Marine Biology Page 79

Impacts of Climate Change in Marine Systems
07 December 2015

14:07

Temperature anomalies for 1961-2010 average oC/decade
• Global air temperatures have increased by 0
...
5oC since 1880
• Median rate of warming 3x faster on land than in sea
Changes in Distribution/Abundance
• Subarctic Calanus finmarchicus
• Cold-temperate Metriolia lucens
• Moving further north, less dominant around UK 1960-1999
• Southward trends in Australia - Extinction due to lack of land masses
Changes in Depth
• North Sea demersal fish assemblage moving deeper by 3
...
vulgata
○ Reproduction delayed 3
...
depressa
○ Advanced 10
...
g
...
g
...
2008

Marine Biology Page 81

• Similar to regional meta-analysis e
...
Tasker et al
...
8km/decade
○ Expansion of biogeographical ranges of 50km/decade
○ Biotic homogenation
○ Different species different rates

• Phenological Responses
○ Mainly norther hemisphere temperate studies
○ Marine: spring 4
...
0SE days/decade
• Trophic Mismatch
○ Predators and prey must exist in same areas
○ Different rates of habitat shift
 Predators move to areas without prey

○ Lower cod condition - less preferential prey

Marine and Terrestrial Rates of Change
• Marine species responding much faster
• Mean temperature not suitable
• Velocity of Climate Change
○ Loarie et al
...
5km/dec
 Oceanic - 21
...
5km/dec
 Oceanic - 27
...

○ Resilience does increase
• Policy Outcomes
○ August 2013
 10 year plan to rebuild lobster stocks
 Department of Primary Industries and Water
○ No take zones
○ Limiting total catch
○ Potential upper size limit on lobsters caught

Marine Biology Page 87



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