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Biological Biological Oceanography 1Oceanography 1

Intro into Bio OceIntro into Bio Oce

Biological Oceanography Vs. Marine Biology

Marine Bio– Study of organisms that

live in the ocean

Bio Oce– Interactions of marine

organisms Biological Abiotic

Biological oceanographers generally study plankton and nekton communities.

Basic marine ecology

Phytoplankton, Zooplankton– Taxonomy– Trophic structure– Nutrient dynamics– Seasonal cycles– Population biology

Terminology

Plankton- – free floating

Can’t “actively” swim against currents

Diatoms, Jellies, copepods ect…

Nekton- – Free swimming

Fish, marine mammals ect…

Pelagic- – open ocean zone

More terms

Benthic- – associated with the sea floor

Lobsters, seastars ect.. Epifuanal-

– lives on sea floor Kelp, coral, sponges ect..

Infaunal- – lives within the sediment

Many worms, clams ect…

But firstAbiotic environment

Ocean zones– Habitat (benthic vs pelagic)

Effects on organisms– Temp– Salinity– Depth (pressure)– Buoyancy (viscosity)– Light– Nutrients

Benthic zonation

Divided based on depth:Divided based on depth:– Supralittoral zone

Above mean high water

– Littoral zone (tidal zone) Between mean high water & mean low waterBetween mean high water & mean low water

– Sublittoral (subtidal zone) Low tide line to edge of continental shelfLow tide line to edge of continental shelf

– Bathyal/abysall zone Deep sea… 200m +

Oceanic HabitatsOceanic Habitats

PelagicPelagic Neritic Zone Neritic Zone

– Shallow water marine environment, Shallow water marine environment, from low water to edge of continental from low water to edge of continental shelfshelf

Oceanic ZoneOceanic Zone– Ocean water seaward of continental Ocean water seaward of continental

shelfshelf

PelagicPelagic Photic Photic

– Receives ample sunlight for Receives ample sunlight for photosynthesisphotosynthesis

– Usually <100mUsually <100m Dysphotic Zone Dysphotic Zone

– Twilight zone Twilight zone – 100m – 450m100m – 450m

Aphotic Aphotic – Dark zoneDark zone– Light insufficient for photosynthesisLight insufficient for photosynthesis

Temperature

Considered to be the most important

factor regulating the distribution of organisms in

the ocean

Ocean temp range– -1.8°-40°C– 90% of the ocean is

colder than 5°C

Temperature

Biology Often follows Isotherms – coral reef distribution, tropical fish,

seasonal plankton blooms, ect….

Temperature

Temp exerts strong control over chemical reactions– In general, biochemical reaction rates

double every 10°C Polar seas

– Slow growth and repo rates, long life spans

Tropical– Fast growth, high repo, short life spans

Temperature

Reproductive cycles often temperature timed– Generally larval, young are more

sensitive to fluctuations than adults

Temperature regulation

Temp at deep sea relatively constant However surface creatures must

adapat Cold blooded vs warm blooded

– Not really

Homotherms- Maintain constant body Poikilotherms-varying body temps

Endotherms- produce heat Ectotherms- external heat (don’t

produce heat)

4 possible combinations

Mammals-”warm blooded”– Homotherms, endotherms

Most inverts- cold blooded– Poikilotherms ectotherms

Other examples– Tuna, large turtles?-Poikilotherms,

endotherms– Deep sea organisms?- Ectotherms,

homotherms

Salinity

Defines “marine” environment Effects on biology?

– Shells (CaCO3 SiO2)

– Osmoregulation– Biochemical reactions

Salinity

Strong haloclines are often present– Surface organisms can tolerate salinity

variations– Mesoplegaic, deep seas

little salinity tolerance

Depth

Salinity

Salinity: regulation

Most invertebrates are isotonic (same) to the surrounding environment

Absolute amount of salts are the same Different concentrations of specific salt

Most vertebrates are hypotonic (less) to seawater

Must actively balance salt concentrations

Salinity: regulation

Diffusion– Movement from areas of high conc. to

areas of low conc.

In the marine environment– Salts– Nutrients– Waste products– Water*

Salinity: OsmosisSalinity: Osmosis Diffusion of water through a semi-Diffusion of water through a semi-

permeable membrane from a dilute permeable membrane from a dilute solution (higher water concentration) into solution (higher water concentration) into a more concentrated solution (lower water a more concentrated solution (lower water concentration). concentration).

Salinity: OsmosisSalinity: Osmosis

Membrane allows passage of the water Membrane allows passage of the water but not the dissolved substances. but not the dissolved substances.

Salinity: OsmosisSalinity: Osmosis

Fish In SaltwaterFish In Saltwater – HypotonicHypotonic: internal salinity is : internal salinity is

less than external less than external environmentenvironment

– Tend to Tend to lose water by osmosis lose water by osmosis Drinks lots of seawaterDrinks lots of seawater Actively secretes excess Actively secretes excess

salts through gillssalts through gills Pees little, but very Pees little, but very

concentratedconcentrated

Salt

Maintaining osmotic balanceMaintaining osmotic balance

Fish FreshwaterFish Freshwater– HypertonicHypertonic: internal salinity : internal salinity

higher than external higher than external environmentenvironment

– Tend to gain water by Tend to gain water by osmosisosmosis Don’t drinkDon’t drink Pees lots of dilute urinePees lots of dilute urine Specialised cells actively Specialised cells actively

uptake the few saltsuptake the few salts

Salt

Maintaining an osmotic Maintaining an osmotic balancebalance

Most marine invertebrates isotonicMost marine invertebrates isotonic– Can’t regulateCan’t regulate

BivalvesBivalves: close valves in fw or air: close valves in fw or air LobstersLobsters: motile, move with salinity: motile, move with salinity

Maintaining an osmotic Maintaining an osmotic balancebalance

Some polychaetes & crustaceans Some polychaetes & crustaceans capable of osmoregulation through capable of osmoregulation through gills gills – Actively change internal salinityActively change internal salinity

Hydrostatic pressure

Pressure created by the water column

Function of density (T&S) and depth 10m (33ft)- 1atm

Which is more compressible?Gasses or Liquids?

Gasses

Pressure

Many shallow water spp. – Use gas for buoyancy control

Can cause problems for marine mammals lungs

Mesopelagic fish, air bladders

deep sea spp. ??– Have “lost” gas spaces,

use oils, fats Pressure insensitive.

Pressure

Marine mammals– Streamlines shapes

Lower oxygen consumption rate

– Myoglobin in tissues Binds to oxygen

– Collapsible lungs– Mammalian dive

reflex Lowers blood flow to

extremities

Buoyancy

Important in energy expenditure– Actively swimming vs. free floating

Some plankton have ~body density as sea water– Neutral buoyancy

Other organisms must adapt– Many different strategies

Buoyancy adaptations

– Some ingenious adaptations Gas champers

– Portuguese man-o-war, Chamber nautilus

Buoyancy adaptations

Swim bladders– Some Fish

Oil droplets, – Decrease density eg. Copepods, diatoms

Ion exchange– Giant squid

Buoyancy

Spines, ruffles feathery appendages

– Increase surface area eg. radilarians, copepods

Denser tissues– Must actively swim, some large

marine mammals, sharks

Lighter tissues– Blubber helps marine mammal

float

Buoyancy

temperature– viscosity

Cold water more viscous– Smaller organisms float better in polar

waters, need less adaptations

Tropicalcopepod

Polar copepod

Light

Why is light important?– Primary production– Light attenuation

Color

– Bioluminescence– Predator/prey relationships– Seasonality

Reproductive cycles

Light

Different wavelengths not transmitted equally

Long wavelengths absorbed first– Red absorbed rapidly

in top 10m– Blue & green

transmitted to greater depths

– Therefore objects appear blue at depth

ROYGBIVROYGBIV

Light In shallow water – all wavelengths

present & natural colors seen Deep – objects more blue:

illuminated by blue light. Red objects appear grey/black

Light

Bioluminescence– Light produced by organism– Caused by Luciferin reacting with the

enzyme luciferaqse– Creates a chemical reaction– Produces light with a 99% efficiency

Light

Sunlight restricts primary production to the photic zone– Adaptations of PP– Use of different pigments at depth– More about this in later classes

Bioluminescence

Can be produced by microscopic plankton

Entire body glows

Predators can incorporate glow Larger sp. have photospheres

– Light producing organs

Bioluminescence

Can be used a means of communication

Can be used in reproductive cycles– Mate attraction – Often tied to lunar cycles

Camouflage– Counter shading

Defense Prey attraction

– Lures

Color

Can be used for a variety of uses

Attract mates Warnings Camouflage

– Blend into background (corals)

– Use of red at depths (eg shrimps)

Fish Coloration Countershading: open ocean fish

– Obliterative countershading: Back is dark green/blue/gray, shades graduate on sides to pure white on belly

– E.g. tuna, marlin, swordfish

NutrientsNutrients Nutrients often limit production in Nutrients often limit production in

photic zone - utilization by 1° photic zone - utilization by 1° producersproducers

Below photic zone, nutrients occur in Below photic zone, nutrients occur in high concentrationshigh concentrations

NutrientsNutrients Nutrients regenerated & returned:Nutrients regenerated & returned:

– UpwellingUpwelling – Turbulence & mixingTurbulence & mixing – Bacterial decompositionBacterial decomposition– Formation and excretion of wasteFormation and excretion of waste

materialsmaterials

NutrientsNutrients Nutrients are non-conservativeNutrients are non-conservative

– Change ratio with biological activityChange ratio with biological activity Nutrient in lowest concentration will Nutrient in lowest concentration will

limit 1limit 1oo productivity productivity Leibig’s law of minimumLeibig’s law of minimum

Nutrients

Don’t worry more to come…

Key concepts

What is Biological Oceanography Nekton vs. plankton Define phytoplankton

– Zooplankton What factors effect the plankton

communities

What are the main ocean zones?– Pelagic vs benthic

What are some general biological patterns– Depth– Seasonality– latitude