introduction to oceanography - uclaschauble/epss15_oceanography/... · lecture 14: tides,...
TRANSCRIPT
1
Bay of Fundy -- low tide, Photo by Dylan Kereluk, . Creative Commons A 2.0 Generic,
http://commons.wikimedia.org/wiki/File:Bay_of_Fundy_-_Tide_Out.jpg
Lecture 14: Tides, Biological Productivity
Introduction to Oceanography Introduction to Oceanography Memorial Day holiday Monday � no lab meetings Go to any other lab section this week (and let the TA know!)
Mudskipper (Periophthalmus modestus) at low tide, photo by OpenCage, Wikimedia Commons, Creative Commons A S-A 2.5, http://commons.wikimedia.org/wiki/File:Periophthalmus_modestus.jpg
Tides Planet-length waves Cyclic, repeating rise & fall of sea level
– Most regular phenomenon in the oceans
Daily tidal variation has great effects on life in & around the ocean (Lab 8)
Photos by Samuel Wantman, Creative Commons A S-A 3.0, http://en.wikipedia.org/wiki/File:Bay_of_Fundy_Low_Tide.jpg and http://en.wikipedia.org/wiki/File:Bay_of_Fundy_High_Tide.jpg
Caused by gravity and between Earth, Moon & Sun, their orbits around each other, and the Earth’s daily spin
Earth-Moon-Sun System • Earth-Sun Distance
150,000,000 km
• Earth-Moon Distance 385,000 km
Much closer to Earth, but much less massive
• Earth Obliquity = 23.5 degrees – Seasons
Figure by Homonculus 2/Geologician, Wikimedia Commons, Creative Commons A 3.0, http://en.wikipedia.org/wiki/
File:Lunar_perturbation.jpg
• Basic Orbital Mechanics • Planetary objects stay in orbit due to balance of Gravity
and Centrifugal forces (at their center of mass) • Like a weight spun on the end of string
Tides are caused by the gravity of the Moon and Sun acting on Earth and its ocean.
Pluto-Charon mutual orbit, Zhatt, Wikimedia Commons, Public Domain, http://en.wikipedia.org/wiki/File:Orbit2.gif
Newton’s cannon, Wikimedia Commons, Creative Commons A S-A 3.0,
http://en.wikipedia.org/wiki/File:Newton_Cannon.svg
• Earth-Moon Distance – 384,000 km
• Revolution period of the Moon – 27.3 Days
• Rotation period of the Moon also 27.3 Days • Synchronous Rotation: We always see the same side of the Moon
To Sun
Brews Ohare, Wikimedia, Public Domain, http://en.wikipedia.org/wiki/File:Earth-
Moon.PNG
Not to scale!
Scaled image of Earth-Moon distance, Nickshanks, Wikimedia Commons, Creative Commons A 2.5
2
Phases of the Moon • New Moon • Waxing Crescent • 1/2 Moon: First
quarter • Full Moon • Etc.
– 7 days/quarter
WAXING CRESCENT
First Quarter
Full Moon
WANING CRESCENTThird Quarter
Tom Ruen, Wikimedia Commons, Public Domain, http://en.wikipedia.org/wiki/
File:Moon_phase_calendar_May2005.png
Phases of the Moon
Figure from NASA Starchild, Public Domain), http://starchild.gsfc.nasa.gov/Images/StarChild/icons/
moon_above.gif
Full New
1st Qtr
3rd Qtr
The Big Picture 3: Bulges
• Moon’s gravitational force acting on the Earth tugs out a tidal bulge towards moon
• Centrifugal force pushes a bulge away from moon on the far side of the Earth – TIDES TRY TO TRACK THE MOON
The Sun’s gravity has a similar, but smaller effect (1/2 as strong).
Figures from U. Tennessee, http://csep10.phys.utk.edu/astr161/lect/time/tides.html
Andrew Buck, Wikimedia Commons, Creative Commons A S-A 3.0, http://commons.wikimedia.org/wiki/File:Tidal_braking.svg
The Moon and Sun both influence tides
Constructive interference: Sun and Moon tidal bulges oriented the same way, resulting in strong tides – Spring Tide Destructive interference: Sun and Moon tidal bulges partially cancel each other, resulting in weak tides – Neap Tide
NOAA, Public Domain, http://oceanservice.noaa.gov/education/kits/tides/media/tide06a_450.gif
Effect of Sun & Moon Together • Spring Tides & Neap Tides
Adapted from figure by Nicky McLean, Wikimedia Commons, Public Domain, http://en.wikipedia.org/wiki/File:Tide.Bridgeport.30d.png
Why is the moon’s effect on the tide greater than the sun’s?
• Gravity balances Centrifugal at Earth’s center of mass
• Elsewhere they don’t cancel – TIDE GENERATING FORCE:
• Tide generating force falls off faster with radius than gravity!
€
Ftides ∝GMMoon
REarth−Moon
3
3
Equilibrium Theory of the Tides Sun is much more massive!
» Msun ~ 3x107 Mmoon
BUT Sun is much further away! » Rsun ~ 400 Rmoon
€
FSFL
≈
GMsRSE3
GMmRmE3
=Ms
Mm
RmE3
RSE3 = 3×107 × 1
4003= 0.47
Solar tide 1/2 as big as lunar tide
Tides in narrow, tapering bays • In narrow bays attached to the ocean, tides can slosh straight
in and out • Large tides can occur when the tidal frequency matches natural
(resonant) oscillations of the bay
Image from NOAA Online School for Weather, Public
Domain, http://www.srh.noaa.gov/jetstream/ocean/fundy_max.htm
Bay of Fundy tides QUESTIONS?
Mont Saint-Michel and Tombelaine (tidal islands), France, Uwe Küchler, Wikimedia Commons, CC A S-A 3.0, http://commons.wikimedia.org/wiki/File:Mont_st_michel_aerial.jpg
Marine Life & Biological Productivity
Estimated marine chlorophyll & terrestrial vegetation coverage map 1997-1998, SeaWiFS/NASA, Public Domain, http://en.wikipedia.org/wiki/File:Seawifs_global_biosphere.jpg
CLASSIFICATION SCHEMES FOR MARINE ORGANISMS
1. Taxonomy: Based on genealogical relationships between organisms (ie, felines)
2. Mode of Nutrition 3. Habitat 4. Mobility
4
Genetic classification: Three Domains of Life 1. Bacteria: Simple single celled organisms, lack
nucleus (E. coli) 2. Archaea: Outwardly similar to Bacteria; many
live in extreme environments (hot springs, nuclear reactors, saline lakes, etc.)
3. Eucarya: Have a membrane-enclosed nucleus and other organelles; include protists, animals, fungi, plants
Whole genome tree of life, diagram by User_A1, based on
Ciccarelli (2006) and Letunic (2007), Public Domain. http://
en.wikipedia.org/wiki/File:CollapsedtreeLabels-
simplified.svg
Bacteria Cyanobacterial colonies, left: NASA, Public Domain, http://microbes.arc.nasa.gov/images/content/gallery/lightms/publication/lyngbya.jpg; right: Hamelin Pool -- Shark’s Bay, Australia, photo by Happy Little Nomad, Wikimedia
commons, CC A S-A 2.0, http://en.wikipedia.org/wiki/File:Stromatolites_in_Shark_Bay.jpg
Thermococcus Gammatolerans, an Archaebacterium, Angels Tapias, Wikimedia Commons, Creative Commons A 3.0 Unported, http://commons.wikimedia.org/wiki/File:Thermococcus_gammatolerans.jpg
Halobacteria (actually Archaea) and Eukarya (Dunaliella salina), San Francisco Bay CA, dro!d, Wikimedia
Commons, Creative Commons A S-A 2.0 http://commons.wikimedia.org/wiki/
File:Salt_ponds_SF_Bay_%28dro!d%29.jpg
Archaea Eukaryota
Copepod, NOAA, Public Domain, http://
www.glerl.noaa.gov/pubs/photogallery/Waterlife/
pages/0737.html
Ostreococcus, a picoplankton (<1x10–6 m across!), Wenche Eikrem
and Jahn Throndsen, University of OsloWikimedia Commons, CC A S-A
2.5, http://en.wikipedia.org/wiki/File:Ostreococcus_RCC143.jpg
Public Domain
Questions?
Comb jelly(?) (Eukaryota), Nick Hobgood, Wikimedia Commons, Creative Commons A S-A 3.0, http://commons.wikimedia.org/wiki/File:Combjelly.jpg
What does it eat? 1. Autotrophs: Make their own food;
are the base of the food chain a. Autotrophs are Primary Producers b. Photosynthesizing plants, algae,
some bacteria (store solar energy) c. Chemosynthetic bacteria
Cyanobacteria, NASA, Public Domain, http://
microbes.arc.nasa.gov/images/content/gallery/lightms/publication/lyngbya.jpg
Sargassum natans (eukarya), James St. John, Creative Commons Attribution 2.0 Generic, https://commons.wikimedia.org/wiki/File:Sargassum_natans_(brown_algae)_(San_Salvador_Island,_Bahamas)_1_(15867880028).jpg
5
What does it eat? 1. Heterotrophs: cannot make their own food; must
eat other organisms or their remains a. Herbivores: eat plants b. Carnivores: eat animals c. Omnivores: eat plants &
animals d. Bacteria: many decompose
dead organic matter (E. coli) Barracuda are heterotrophs, NOAA, Public Domain, http://www.photolib.noaa.gov/htmls/
reef2567.htm
So are yeast, Masur, Wikimedia Commons, Creative Commons A S-A 2.5, http://en.wikipedia.org/wiki/File:S_cerevisiae_under_DIC_microscopy.jpg
Photosynthesis Living systems require chemical energy Chlorophyll: a green pigment that captures photons and transfers their energy to
electrons, an through a series of steps creates carbohydrate molecules (chemical energy) and oxygen.
Chlorophyll looks green because it absorbs red and blue light, and reflects green light
Sargassum algae, NOAA, Public Domain, http://oceanexplorer.noaa.gov/explorations/02sab/logs/aug09/media/
lines.html
Adapted from figure
by Aushulz, Wikimedia Commons,
Creative Commons A
S-A 3.0, http://
commons.wikimedia.org/
wiki/File:Chlorophyll_ab_spe
ctra2.PNG
Photosynthesis Reaction
6CO2 + 6H2O ——> C6H12O6 + 6O2
sunlight
Carbon dioxide
water (yields) Glucose (a sugar)
Oxygen + +
Typically, ~100 grams carbon/ year / meter2 is fixed to sugar in the open ocean
PRIMARY PRODUCTION
• Amount of inorganic carbon (mainly CO2) “fixed” by autotrophic organisms into organic compounds – Based on reactions harnessing solar or
chemical energy
Respiration • Respiration: opposite reaction of photosynthesis • Dis-assembly of carbohydrate (food) molecules in the
presence of oxygen to release chemical energy • The main byproducts of respiration are H2O and CO2.
These are released to the environment • Both plants & animals use respiration • Some bacteria & archea also respire
C6H12O6 + 6O2 ——> 6CO2 + 6H2O
Carbon dioxide
water (yields) Glucose (a sugar) Oxygen + +
+ ENERGY
Questions
Sargassum, photo from South Atlantic Fishery Management Council, http://www.safmc.net/Portals/6/weedline%202.jpg
6
How can we measure productivity? -Timed weighing of autotrophs
Good for big land plants, possible for large seaweed.
However, measurements are only local.
Hard to weigh microorganisms, particularly when they have a very short lifecycle.
-Timed “weighing” of inorganic carbonAdd labeled inorganic carbon (14CO2) to ocean water
See how fast organisms convert it to organic molecules
Works well for microorganisms, but still a local measurement.
Color-imetry! (yes, it means what you think) - Chorophyll enables photosynthesis by absorbing blue and red
light. Green light is reflected or scattered. - Green ocean implies lots of chlorophyll
- Lots of chlorophyll implies lots of productivity!
- Satellites like SEASTAR can measure color from space. This makes colorimetry ideal for global ocean surveys, if it works. This technique will be bad for long-lived plants (chlorophyll is present even when big plants aren’t active, I.e. spruce trees)
How can we measure productivity?
HYPOTHESIS: Green color in the ocean correlates with primary productivity.
PREDICTION: Productivity estimated from color should be the same as productivity measured by “weighing” uptake of inorganic carbon.
Colorimetry compared with “weighing”
From Measured uptake of inorganic 14C
M.J. Behrenfeld & P.G. Falkowski. 1997. Photosynthetic rates derived from satellite-based chlorophyll concentration. Limnol. Oceanogr. 42:1-20
From
Sat
ellit
e C
olor
imet
ry There is good agreement, but also a lot of scatter.�Colorimetry may be a reasonable model, but we still don’t know all the details!
Productivity from SeaWiFS
SeaWiFS/NASA/Rutgers University, Public Domain http://marine.rutgers.edu./opp/swf/Production/gif_files/PP_9809_9908.gif
Figure from University of Michigan, http://www.globalchange.umich.edu/
globalchange1/current/lectures/kling/energyflow/typeeco2.gif
Primary Production 1. Amount depends on:
a. Driving Energy (Solar or chemical) b. Nutrients
2. Regions of Highest Productivity a. Continental margins: Upwelling (Ekman
pumping) and vertical mixing common along margins. Also close to rivers, dust sources
b. Equatorial Divergences c. Antarctic Divergence d. Northern Pacific & Northern Atlantic
i. Deepwater upwelling in Pacific; Divergence within subpolar Arctic/Atlantic gyres
7
Primary Production 3. Regions of Lowest Productivity
a. Interiors of subtropical gyres i. This is where ocean water is most stably
stratified --- Strong, stable pycnocline, little vertical
mixing. Few nutrients are brought up to the surface.
--- These are the “deserts” of the ocean, most nutrients lost as dead organisms sink into the deep ocean
Primary Production 4. Primary Producers (Autrotrophs)
a. Eukaryotic Algae (Seaweeds & Single celled photosynthesizers)
i. Benthic (coastal): minor component i. Seaweeds
ii. Pelagic phytoplankton: primary component i. Diatoms, dinoflagellates, coccolithophores, etc.
b. Cyanobacteria: blue-green algae c. Picoplankton / Archea(?) d. Chemosynthetic Bacteria: Use inorganic
compounds to get energy i. They oxidize compounds such as H2S (Hydrogen
sulfide)
Questions
Abalone, Oregon Coast Aquarium, photo by Little Mountain 5,
Wikimedia Commons, Creative Commons A S-A 3.0, http://
commons.wikimedia.org/wiki/File:Abalone_OCA.jpg
HABITAT
NOAA, Public Domain, http://oceanexplorer.noaa.gov/explorations/04deepscope/background/deeplight/media/diagram3_600.jpg
Ocean Habitats
• Where do organisms live in the oceans? – Biozones
• Benthic vs. Pelagic – Sea floor vs. Free-floating/free-swimming
– Light Zones • Photic, Dysphotic, Aphotic
Habitat
1. Pelagic (oceanic): live in the water column
2. Benthic: Live in or on ocean bottom Whale shark, Georgia aquarium, Zac Wolf, Creative Commons A S-A 2.5, http://commons.wikimedia.org/wiki/File:Whale-shark-enhanced.jpg
Coral polyp, Nick Hobgood, Creative Commons A S-A 3.0, http://commons.wikimedia.org/wiki/
File:Euphyllia_glabrescens_%28Hard_coral%29_with_polyps_extended.jpg
8
Ocean Habitats
• Neritic vs. Oceanic– Shelf waters vs. deep waters– Neritic/Sublittoral: photic zone reaches to sea floor
Figure by Chris_huh, Wikimedia Commons, Creative Commons A S-A 3.0, http://en.wikipedia.org/wiki/File:Oceanic_divisions.svg
Relative Habitat Sizes
• Abyssal pelagic: 54% oceans by volume • Abyssal: 75% sea floor by area
• Yet most of the bioproduction occurs elsewhere, near the surface
Questions
Spotted garden eel, photo by Nick Hobgood, Wikimedia Commons, Creative Commons A S-
A 3.0, http://commons.wikimedia.org/wiki/File:Heteroconger_hassi_%28Spotted_garden_
eel%29.jpg
Zonation by Lighting
• Photic Zone: lit by sunlight, ~ 100 - 500m deep – Euphotic Zone: autotrophs capture more
energy than they use; net fixation of carbon; net production of O2
– Dysphotic Zone: Not enough light for profitable photosynthesis
• Aphotic Zone: Permanent darkness
Ope
n O
cean
NOAA, Public Domain, http://oceanexplorer.noaa.gov/explorations/04deepscope/background/deeplight/media/diagram3_600.jpg
Coastal Ocean
NOAA, Public Domain, http://oceanexplorer.noaa.gov/explorations/04deepscope/background/deeplight/media/diagram3_600.jpg