Primary Productivity in the Marine Environment

Fig. 13.5

Primary productivity Energy is converted into organic matter

to be used by cellsPhotosynthesisPhotosynthesis using solar radiation○ 99.9% of marine life relies directly or indirectly

on photosynthesis for food

ChemosynthesisChemosynthesis using chemical reactions Happens in hydrothermal vents at bottom of ocean

with no light

Remember, energy cannot be created or destroyed – it only changes form

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 respirationNeed input of carbon (i.e. glucose) and oxygen for

cellular respirationThat 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- Excess moves it’s way up the food chain

Now we are going to revisit photosynthesis and cellular respiration

Remember, we are following electrons and protonsOIL RIG – Oxidize it loses, reduced it gains

Photosynthesis – process of fixing carbon from the atmosphere into organic material that now has energy from the sun trapped in the bonds of the molecule

What is the chemical formula for photosynthesis?

Review this Prezi: http://prezi.com/2byn9gmriian/photosynthesis/?utm_campaign=share&utm_medium=copy

Cellular RespirationReview this Prezi:

http://prezi.com/8_qehzkw-vuk/cellular-respiration/?utm_campaign=share&utm_medium=copy

Is glucose the only molecule that can be broken down and oxidized during cellular respiration to gain energy?

Measuring primary productivity Capture plankton

Plankton nets Ocean color

ChlorophyllChlorophyll colors seawaterSeaWiFs on satellite

Factors affecting primary productivity NutrientsNutrients

Nitrate, phosphorous, iron, silicaNitrate, phosphorous, iron, silicaNeeded for bacteria and phytoplankton to make more

DNA, proteins, etc to make more of themselvesMost from river runoff

Productivity high along continental margins because of nutrient runoff

Solar radiationSolar radiationUppermost 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. 13.6ahttp://cordellbank.noaa.gov/images/environment/

upwelling_470.jpg

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

AngiospermsAngiospermsSeed-bearing flowering plants,

example is mangroves Macroscopic (large) algaeMacroscopic (large) algae

Larger seaweeds, like kelpLarger seaweeds, like kelp Microscopic (small) algaeMicroscopic (small) algae

phytoplanktonphytoplankton Photosynthetic bacteriaPhotosynthetic bacteria

Macroscopic algae – “Seaweeds”

Brown algaeBrown algae

http://www.starfish.ch/photos/plants-Pflanzen/Sargassum.jpg

Green algaeGreen algae

Macroscopic algae – Macroscopic algae – “Seaweeds”“Seaweeds”

http://www.sms.si.edu/IRLspec/images/cbrachypus2.jpg

Caulerpa brachypus, an invasive species in the Indian River Lagoon

http://192.107.66.195/Buoy/System_Description_Codium_Fragile.jpg

Codium

Macroscopic algae – “Seaweeds”

Red algaeRed 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 are planktonic -

phytoplankton

Golden algaeGolden algae DiatomsDiatoms (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

http://biologi.uio.no/akv/forskning/mbot/images

Microscopic algae

CoccolithophoresCoccolithophores (plates of ate)○ Flagellated○ calcium carbon plates possibly sunshades○ Coccolithid ooze fossilized in white cliffs of

Dover

http://www.esa.int/images

Microscopic algae DinoflagellatesDinoflagellates

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://www.hku.hk/ecology/porcupine/por24gif/Karenia-digitata.jpghttp://oceanworld.tamu.edu/students/fisheries/images/red_tide_bloom_1.jpg

Microscopic algae DinoflagellatesDinoflagellates

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 Cyanobacteria – many different species Extremely small May be responsible for half of total

photosynthetic biomass in oceans

http://silicasecchidisk.conncoll.edu/Pics/Other%20Algae/Blue_Green%20jpegs/Gloeocapsa_Key45.jpg

Gleocapsa

http://www.micrographia.com/specbiol/bacteri/bacter/bact0200/anabae03.jpg

Anabaena

Regional primary productivity Varies from very low to very high

depending onDistribution of nutrientsDistribution of nutrientsSeasonal changes in solar radiationSeasonal changes in solar radiation

About 90% of surface biomass decomposed in surface ocean

About 10% sinks to deeper oceanOnly 1% organic matter not decomposed in

deep ocean reaches bottomBiological pump (CO2 and nutrients to sea floor

sediments)

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

Tropical ocean productivity Permanent thermocline is barrier to vertical

mixing Low rate of 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). Examples of these areas are:

Equatorial upwellingEquatorial upwellingCoastal upwelling (river runoff, etc.)Coastal upwelling (river runoff, etc.)

Coral reefsCoral reefs

Energy flow in marine ecosystems ConsumersConsumers eat other organisms

Herbivores (primary consumers)CarnivoresOmnivoresBacteriovores

DecomposersDecomposers breaking down dead organisms or waste products

Nutrient flow in marine ecosystems

Nutrients cycled from one chemical form to another

BiogeochemicalBiogeochemical cyclingExample, nutrients fixed

by producersPassed onto consumersSome nutrients released

to seawater through decomposers

Nutrients can be recycled through upwelling

Feeding strategies Suspension feeding or filter feedingSuspension feeding or filter feeding

Take in seawater and filter out usable organic matter

Deposit feedingDeposit feedingTake in detritus and sediment and

extract usable organic matter Carnivorous feedingCarnivorous feeding

Organisms capture and eat other animals

Trophic levels Feeding stage is trophic leveltrophic 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

Food chain Food web Primary producer Herbivore One or more

carnivores

Branching network of many consumers

Consumers more likely to survive with alternative food sources

http://users.aber.ac.uk/pmm1

• Food webs are more complex & more realistic• Consumers often operate at two or more

levels

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

Fig. 13.23

Marine fisheries

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 BycatchBycatch - - Non-commercial

species (or juveniles of commercial species) taken incidentally by commercial fishers

Bycatch may be 25% or 800% of commercial fishBirds, turtles, dolphins,

sharks

http://www.motherjones.com/news/featurex/2006/03/bycatch_265x181.jpg

Incidental catch or bycatch Technology to help reduce

bycatchDolphin-safe tunaTEDs – 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

Fisheries management

Regulate fishing Closings – Cod fisheries of

New EnglandSeasonsSize 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/70062/fig10b.gif

http://www.cefas.co.uk/media/70037/fig7b.gif

Plaice

Fisheries management Conflicting interests

Conservation vs. economic – “tragedy of the commons”

Self-sustaining marine ecosystems

Human employmentInternational watersEnforcement 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 Consumer choices in seafood Consume and purchase

seafood from healthy, thriving fisheriesExamples, farmed seafood,

Alaska salmon

Avoid overfished or depleted seafoodExamples, bluefin tuna, shark,

shrimp, swordfishVisit: ORCA's Blue Diet page

http://marineresearch.ca/hawaii/wp-content/uploads/tuna-auction-largeview.jpg

Figure 13.28