Transcript Chapter 13: Biological productivity and energy transfer

CHAPTER 13
Biological Productivity and Energy Transfer
Fig. 13.5
Primary productivity

Energy is converted into organic matter
to be used by cells
 Photosynthesis using solar radiation
○ 99.9% of marine life relies directly or
indirectly on photosynthesis for food
 Chemosynthesis using chemical reactions
 Happens in hydrothermal vents at bottom of ocean
with no light
Let’s talk about energy

Biological organisms need biochemical
processes to happen in an orderly fashion
in order to maintain life
○ Needs constant input of energy to maintain that
order
○ Our cells need energy in form of ATP
 ATP formed during cellular respiration
 Need input of carbon (i.e. glucose) and oxygen for
cellular respiration
 That carbon source and oxygen comes from
photosynthesis (primary productivity)
Photosynthetic productivity

Chemical reaction that stores solar energy
in organic molecules
○ Photosynthetic organisms fix carbon and energy
from atmosphere
- Also incorporate other elements and molecules
necessary for life (nitrogen, phosphorus, etc)
- What do we need these for? For making proteins,
lipids, DNA, etc.
- Use some of that for their own energy source for life
- Rest moves it’s way up the food chain
Measuring primary productivity


Capture plankton
 Plankton nets
Ocean color
 Chlorophyll colors seawater
 SeaWiFs on satellite
Factors affecting primary
productivity

Nutrients
 Nitrate, phosphorous, iron, silica
 Needed for bacteria and phytoplankton to make more
DNA, proteins, etc to make more of themselves
 Most from river runoff
 Productivity high along continental margins

Solar radiation
 Uppermost surface seawater and shallow seafloor are
most productive, need light!
 Euphotic zone surface to about 100 m (330 ft)
Upwelling and nutrient supply


Cooler, deeper seawater nutrient-rich
Areas of coastal upwelling sites of high
productivity
Fig. 13.6a
http://cordellbank.noaa.gov/images/environment/upwelling_470.jp
Light transmission
Visible light of the electromagnetic
spectrum
 Blue wavelengths penetrate deepest
 Longer wavelengths (red, orange)
absorbed first

Light transmission in ocean


Color of ocean ranges from deep
blue to yellow-green
Factors
 Water depth
 Turbidity from runoff
 Photosynthetic pigment
(chlorophyll)
○ “dirty” water in coastal areas,
lagoons, etc. are areas of high
productivity, lots of plankton
(preventing that “blue” color)
http://upload.wikimedia.org/wikipedia/commons/a/a5/LightningVolt_Deep_Blue_Sea.jpg
Types of photosynthetic marine organisms
 Anthophyta
 Seed-bearing plants, example is
mangroves
 Macroscopic (large) algae
 Larger seaweeds, like kelp
 Microscopic
(small) algae
 phytoplankton
 Photosynthetic
bacteria
Anthophyta



Only in shallow coastal
waters
Primarily seagrasses &
Mangroves
Very few plant species
can tolerate salt water
http://celebrating200years.noaa.gov/events/sanctuaries/seagrass_meadow650.jpg
Macroscopic algae – “Seaweeds”

Brown algae
http://www.starfish.ch/photos/plants-Pflanzen/Sargassum.jpg
Macroscopic algae – “Seaweeds”

Green algae
Codium
Caulerpa brachypus, an invasive
species in the Indian River Lagoon
http://www.sms.si.edu/IRLspec/images/cbrachypus2.jpg
http://192.107.66.195/Buoy/System_Description_Codium_Fragile.jpg
Macroscopic algae – “Seaweeds”

Red algae
 Most abundant and most widespread
of “seaweeds”
 Varied colors
http://www.dnrec.state.de.us/MacroAlgae/information/Indentifying.shtml
http://www.agen.ufl.edu/~chyn/age2062/lect/lect_15/22_14B.GIF
Microscopic algae

Produce food for 99% of
marine animals
Most planktonic

Golden algae

http://biologi.uio.no/akv/forskning/mbot/images
 Diatoms (tests of silica)
○ Most abundant single-celled
algae – 5600+ spp.
○ Silicate skeletons – pillbox or
rod-shaped  ooze
○ Some w/ sticky threads,
spines  slows sinking
www.bren.ucsb.edu/ facilities/MEIAF
Microscopic algae
 Coccolithophores (plates of ate)
○ Flagellated
○ calcium carbon plates  possibly sunshades
○ Coccolithid ooze  fossilized in white cliffs of Dover
http://www.esa.int/images
Microscopic algae

Dinoflagellates
 Mostly autotrophic; some heterotrophic or both
 Flagella in grooves for locomotion
 Many bioluminescent
 Often toxic when toxin is concentrated due to bloom
○
Red tides (algal blooms)  fish kills (increase nutrients,
runoff)
http://oceanworld.tamu.edu/students/fisheries/images/red_tide_bloom_1.jpg
http://www.hku.hk/ecology/porcupine/por24gif/Karenia-digitata.jpg
 Manatees died in
Brevard and Volusia
counties in 2007, and on
west coast, possibly due
to red tide
 concentrates on
seagrass manatees
eat
 Breath in toxic
fumes
http://www.nepa.gov.jm/yourenv/biodiversity/Species/gifs/man
atee.jpg
Microscopic algae

Dinoflagellates
Pfiesteria found in temperate coastal waters
 Ciguatera - illness caused from eating fish coated with
Gambierdiscus toxicus
 Paralytic, diarhetic, amnesic shellfish poisoning

Pfiesteria
http://www.odu.edu/sci/biology/pfiesteria
Photosynthetic bacteria
Extremely small
 May be responsible for half of total
photosynthetic biomass in oceans

Anabaena
http://www.micrographia.com/specbiol/bacteri/bacter/bact0
200/anabae03.jpg
Gleocapsa
http://silicasecchidisk.conncoll.edu/Pics/Other%20Algae/Blue_Green%20
jpegs/Gloeocapsa_Key45.jpg
Regional primary productivity

Varies from very low to very high depending
on
 Distribution of nutrients
 Seasonal changes in solar radiation
About 90% of surface biomass decomposed in
surface ocean
 About 10% sinks to deeper ocean

 Only 1% organic matter not decomposed in deep
ocean  reaches bottom
 Biological pump (CO2 and nutrients to sea floor
sediments)
Table 13.1
= 4785
Smaller than land but this is by meter2
(think about how large ocean is compared to land)
= 6450
Temperate ocean productivity

Seasonal variation with temperature/light/nutrients
 Winter:
○ High winter winds  mixing of sediments/plankton
○ Low light & few phytoplankton  nutrients increase
 Spring:
○ Phytoplankton blooms with more light, nutrients
○ Bloom continues until…
Nutrients run out
 Herbivores eat enough phytoplankton



Summer: often low production due to lack of nutrients
Fall: Often second bloom, as winds bring up nutrients
Polar ocean productivity


Winter darkness
Summer sunlight (sometimes 24 hours/day)
 Phytoplankton (diatoms) bloom
 Zooplankton (mainly small crustaceans)
productivity follows
 HIGH PRODUCTIVITY!!
 Example
Arctic Ocean
Polar ocean productivity
Availability of sunlight during
summer and
 High nutrients due to
upwelling of North Atlantic
Deep Water

 No thermocline
 No barrier to vertical mixing

Blue whales migrate to feed
on maximum zooplankton
productivity
Tropical ocean productivity
Permanent thermocline is barrier to vertical
mixing
 Low rate primary productivity (lack of nutrients)
above thermocline

○ That’s why tropical waters tend to be clear and blue
Tropical ocean productivity
Productivity in tropical ocean is lower
than that of polar oceans
 That’s why tropical oceans look clear
 Tropical oceans are deserts with some
high areas of sporadic productivity
(oasis)

 Equatorial upwelling
 Coastal upwelling (river runoff, etc.)
 Coral reefs
Energy flow in marine ecosystems

Consumers eat other organisms





Herbivores (primary consumers)
Carnivores
Omnivores
Bacteriovores
Decomposers breaking down dead organisms
or waste products
Nutrient flow in marine ecosystems
Nutrients cycled from
one chemical form to
another
 Biogeochemical cycling

 Example, nutrients fixed
by producers
 Passed onto consumers
 Some nutrients released
to seawater through
decomposers
 Nutrients can be
recycled through
upwelling
Feeding strategies

Suspension feeding or filter feeding
 Take in seawater and filter out usable
organic matter

Deposit feeding
 Take in detritus and sediment and extract
usable organic matter

Carnivorous feeding
 Organisms capture and eat other animals
Trophic levels



Feeding stage is
trophic level
Chemical energy is
transferred from
producers to
consumers
On average, about 10%
of energy is
transferred to next
trophic level

Much of the energy is
lost as heat
Fig. 13-18
Food chain



Primary producer
Herbivore
One or more carnivores
Food web


Branching network of
many consumers
Consumers more likely
to survive with
alternative food sources
•
Food webs are more complex & more realistic
• Consumers often operate at two or more levels
http://users.aber.ac.uk/pmm1
http://www-sci.pac.dfo-mpo.gc.ca/mehsd/images/ross_photos
Biomass
pyramid


Both number of
individuals and
total biomass
(weight)
decrease at
successive
trophic levels
Organisms
increase in size
Symbiosis

Organisms associate
in beneficial
relationship
 Commensalism
○ One benefits without
harm to other
 Mutualism
○ Mutually beneficial
 Parasitism
○ One benefits and may
harm the other
Marine fisheries



Fig. 13.23
Commercial fishing
Most tonnage from
continental shelves
and coastal
fisheries, compared
to open ocean
fisheries
Over 20% of catch
from areas of
upwelling that make
up 0.1% of ocean
surface area
Overfishing




Taking more fish than is sustainable over long periods
Remaining fish younger, smaller
About 30% of fish stocks depleted or overfished
About 47% fished at biological limit

Aquaculture becoming a more significant
component of world fisheries
Incidental catch or bycatch
Bycatch - Non-commercial
species (or juveniles of
commercial species) taken
incidentally by commercial
fishers
 Bycatch may be 25% or 800%
of commercial fish
 Birds, turtles, dolphins,
sharks

http://www.motherjones.com/news/featurex/2006/03/bycatch_265x181.jpg
Incidental catch or bycatch


Technology to help reduce
bycatch
 Dolphin-safe tuna
 TEDs – turtle exclusion
devices
Driftnets or gill nets banned in
1989
 Gill nets banned in Florida by
constitutional amendment in 1994
http://www.st.nmfs.noaa.gov/st4/images/TurtTEDBlu_small.jpg
http://www.cefas.co.uk/media/70062/fig10b.gif
Fisheries management

Plaice
Regulate fishing
 Closings – Cod fisheries of
New England
 Seasons
 Size limits
○ Minimum size limits –
protects juveniles, less
effective
○ Min/max size (slot) limits –
preserves juvs and larger
adults (contribute most
reproductive effort)
http://www.cefas.co.uk/media/70037/fig7b.gif
Fisheries management

Conflicting interests
 Conservation vs. economic –




“tragedy of the commons”
Self-sustaining marine
ecosystems
Human employment
International waters
Enforcement difficult
“Tragedy of the commons” – All participants
must agree to conserve the commons, but any
one can force the destruction of the commons
http://farm1.static.flickr.com/178/380993834_09864a282c.jpg
Fisheries management

Governments subsidize fishing
 Many large fishing vessels – often purchased
with economic stimulus loans
 1995 world fishing fleet spent $124 billion to
catch $70 billion worth of fish
Activists deploying a banner
reading, 'No Fish No Future'
next to tuna fishing vessel
Albatun Tre, which they
claim is the world's largest
tuna fishing vessel
http://www.telegraph.co.uk/earth/main.jhtml?xml=/earth/2008/05/30/eatuna130.xml
Fisheries management
Northwest Atlantic Fisheries such as
Grand Banks and Georges Bank
 Canada and U.S. restrict fishing and
enforce bans
 Some fish stocks in North Atlantic
rebounding
 Other fish stocks still in decline (e.g.,
cod)

Fisheries management
Consumer choices in seafood
 Consume and purchase seafood
from healthy, thriving
fisheries

 Examples, farmed seafood, Alaska
salmon

Avoid overfished or depleted
seafood
 Examples, bluefin tuna, shark,
shrimp, swordfish
 Visit: ORCA's Blue Diet page
http://marineresearch.ca/hawaii/wpcontent/uploads/tuna-auction-largeview.jpg
Figure 13.28