CHAPTER 13 Biological Productivity and Energy Transfer Fig. 13.5

Primary productivity  Rate at which energy is stored in organic matter Photosynthesis Photosynthesis using solar radiation ○ 99.9% of marine life relies directly or indirectly on photosynthesis for food Chemosynthesis 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 Chlorophyll colors seawater SeaWiFs on satellite

Factors affecting primary productivity  Nutrients Nitrate, phosphorous, iron, silica Nitrate, phosphorous, iron, silica Most from river runoff Productivity high along continental margins  Solar radiation Uppermost surface seawater and shallow seafloor 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

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)

Types of photosynthetic marine organisms  Anthophyta Seed-bearing plants, example is mangroves  Macroscopic (large) algae Larger seaweeds, like kelp Larger seaweeds, like kelp  Microscopic (small) algae phytoplankton phytoplankton  Photosynthetic bacteria

Anthophyta  Only in shallow coastal waters seagrasses Mangroves  Primarily seagrasses & Mangroves  Very few plant species can tolerate salt water

Macroscopic algae – “Seaweeds”  Brown algae Sargassum

 Green algae Macroscopic algae – “Seaweeds” Caulerpa brachypus, an invasive species in the Indian River Lagoon Codium

Macroscopic algae – “Seaweeds”  Red algae Most abundant and most widespread of “seaweeds” Varied colors

Microscopic algae  Produce food for 99% of marine animals  Most planktonic  Golden algae Diatoms Diatoms (tests of silica) ○ Most abundant single-celled algae – spp. ○ Silicate skeletons – pillbox or rod-shaped  ooze ○ Some w/ sticky threads, spines  slows sinking facilities/MEIAF

Microscopic algae Coccolithophores Coccolithophores (plates of ate) ○ Flagellated ○ calcium carbon plates  possibly sunshades ○ Coccolithid ooze  fossilized in white cliffs of Dover

Microscopic algae  Dinoflagellates Mostly autotrophic; some heterotrophic or both Flagella in grooves for locomotion Many bioluminescent Often toxic ○ Red tides (algal blooms)  fish kills (increase nutrients, runoff) Karenia spp., the alga that causes red tide

 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 ecies/gifs/manatee.jpg

Microscopic algae  Dinoflagellates Pfiesteria in temperate coastal waters Ciguatera (from) Gambierdiscus toxicus in tropical fishes Paralytic, diarhetic, amnesic shellfish poisoning Pfiesteria biology/plants/algae/ images/Gambitox.jpg Gambierdiscus Alexandrium – paralytic shellfish

Photosynthetic bacteria  Extremely small  May be responsible for half of total photosynthetic biomass in oceans Blue_Green%20jpegs/Gloeocapsa_Key45.jpg Gleocapsa bacter/bact0200/anabae03.jpg Anabaena

Regional primary productivity  Varies from very low to very high depending on Distribution of nutrients Distribution of nutrients Seasonal changes in solar radiation 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 (CO 2 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 Fig

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 Equatorial upwelling Coastal upwelling (river runoff, etc.) Coastal upwelling (river runoff, etc.) Coral reefs Coral reefs

Energy flow in marine ecosystems  Consumers  Consumers eat other organisms Herbivores (primary consumers) Carnivores Omnivores Bacteriovores  Decomposers  Decomposers breaking down dead organisms or waste products

Nutrient flow in marine ecosystems  Nutrients cycled from one chemical form to another  Biogeochemical  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 trophic level  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

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

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

Biomass pyramid  Both number of individuals and total biomass (weight) decrease at successive trophic levels  Organisms increase in size Fig

Symbiosis  Organisms associate in beneficial relationship Commensalism Commensalism ○ One benefits without harm to other Mutualism Mutualism ○ Mutually beneficial Parasitism Parasitism ○ One benefits and may harm the other

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 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 State of exploitation of selected stock or species groups for which assesment information is available, by major marine fishing areas, Figure A2.4 - Stage of development of the 200 major marine fishery resources: 1950–2000

 Aquaculture becoming a more significant component of world fisheries Marine fisheries leveling off over last years

Figure 13.26

Incidental catch or bycatch  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

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 BD8-4D7B-B75D-F1480DC74C5D/207170/p6281atl.jpg

Fisheries management  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) Plaice

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

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 attachments/Indonesian%20fishing%20boat%202.JPG 34m Fishing Vessel Apprehended In Australian Waters, April 2008 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

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 pageORCA's Blue Diet page content/uploads/tuna-auction-largeview.jpg

Figure 13.28